OAE2 and the Platycopid Signal

NASA Astrophysics Data System (ADS)

Horne, David

2010-05-01

More than 20 years ago the first detailed multi-proxy investigation of the Cenomanian-Turonian Boundary Event (CTBE) in SE England revealed a distinctive pattern of changes in ostracod assemblages. Coincident with a major global positive carbon stable-isotope excursion during Oceanic Anoxic Event 2 (OAE 2), a marked reduction in floral and faunal diversity was attributed to decreasing levels of dissolved oxygen, consequent on an intensification and expansion of the oceanic Oxygen Minimum Zone into shelf seas. As podocopid ostracod taxa became locally extinct, platycopid ostracods became dominant; from this observation was developed the "Platycopid Signal" hypothesis which claimed that dominance of platycopids in ostracod assemblages signalled dysaerobic conditions on the sea floor. Subsequently this interpretation was widely accepted and applied to the recognition of other dysaerobic intervals in the geological record. However, the modern biological and ecological support claimed for the Platycopid Signal has been challenged and found wanting. In the case of the much-studied CTBE sections in SE England this effectively removes the only remaining pillar of support for the notion of bottom-water dysaerobia in the Anglo-Paris Basin during OAE2, which has already been contradicted by macrofossil, trace fossil and geochemical evidence. A new interpretation of the Platycopid Signal as indicative of oligotrophy is supported by other palaeontological proxy evidence in the CTBE and by observations that living platycopids appear to be adapted to filter-feed on nano- and picoplankton phytodetritus which predominates in oligotrophic conditions. Brandão, S.N. & Horne, D.J., 2009. The Platycopid Signal of oxygen depletion in the ocean: a critical evaluation of the evidence from modern ostracod biology, ecology and depth distribution. Palaeogeography, Palaeoclimatology, Palaeoecology, 286, 126-133. Horne, D.J., Brandão, S.N. & Slipper, I.J. The Platycopid Signal deciphered

Evolution and Termination of Oceanic Anoxic Event 2: Testing the impact of organic matter sulfurization on benthic-pelagic coupling during OAE2

NASA Astrophysics Data System (ADS)

Hülse, D.; Arndt, S.; Ridgwell, A.

2016-12-01

Oceanic Anoxic Events (OAEs) represent severe disturbances of the global carbon, oxygen and nutrient cycles of the ocean. The archetypal example is OAE2 ( 93.5 Ma), which is characterized by widespread bottom water anoxia and photic zone euxinia. One way to explain these conditions is via increased oxygen demand in the water column resulting from enhanced primary productivity (PP), itself fuelled by increased nutrient availability for instance from the sediments as the burial efficiency of phosphorus declines when bottom waters become anoxic. The recovery from OAE like conditions is thought to involve the permanent removal of excess CO2 from the atmosphere and ocean by burying carbon in the form of organic matter (OM) in marine sediments, which is consistent with the geological record of widespread black shale formation. A number of possible controls on enhanced OM burial have previously been proposed and assessed, such as elevated depositional fluxes, higher clay mineral availability, or reduced oxygenation. Here we explore a 4th possible mechanism - organic matter sulfurization. During sulfurization, reduced inorganic sulfur species (e.g. H2S) react with OM, resulting in the formation of organic sulfur compounds which are less prone to bacterial degradation. Although studies indicate the global significance of this process for OAE2, its implications on Cretaceous benthic-pelagic coupling and thus OAE2 evolution and recovery has not yet been quantified and tested with a 3D Earth system model. The major hurdle is the high computational cost of simulating the essential redox reactions in marine sediments, which are critical to quantify the burial of OM and benthic recycling fluxes of chemical compounds. In order to close this knowledge gap, we developed a new, mechanistic representation of OM preservation in marine sediments (OMEN-SED) and coupled it to a 3D Earth system model (cGENIE). Using this new model we explore the impact of organic matter sulfurization on

Unpacking paleoenvironmental change across OAE2 using paired d34S records of pyrite and organic matter

NASA Astrophysics Data System (ADS)

Raven, M. R.; Gomes, M.; Fike, D. A.

2017-12-01

Pyrite sulfur isotopes have proven to be a powerful tool for reconstructing major changes in global redox state and the emergence of microbial metabolisms. Still, pyrite can be a challenging archive, as its formation depends on the availability of reactive iron species and can occur over multiple generations of sedimentary processes. Accordingly, pyrite δ34S records commonly have large point-to-point variability reflecting local processes. By pairing pyrite δ34S records with those of coexisting organic matter (OM), including both kerogens and extractable bitumens, we can begin to parse the various potential causes of this variability and gain greater insights into changes in the sedimentary paleoenvironment. Here, we present the first collection of records of OM δ34S for the Cretaceous, focusing on sections spanning Ocean Anoxic Event 2 (OAE2, 94 Mya), a period of globally widespread marine anoxia and carbon cycle disruption. In carbonates and shales from OAE2 in Pont d'Issole, France, pyrite and OM δ34S values vary in parallel throughout most of the section, consistent with their shared sulfide source. There are also distinct exceptions: In one interval, an excursion in pyrite δ34S is entirely absent from the organic sulfur record but associated with unusual organic sulfur redox speciation (by XAS), potentially reflecting later exposure to oxic porewaters. Across the core interval of shale deposition during OAE2, the offset between pyrite and OM δ34S values declines smoothly from +17.4 to -7.9‰, which we interpret in terms of changes in the speciation of detrital iron minerals that may have regional implications. We then compare these results with data for other well-characterized OAE2 sections, including Cismon (Italy), Tarfaya (Morocco), and the Demerara Rise (offshore Brazil), which represent environments with a variety of apparent redox states. These paired pyrite - OM δ34S profiles yield new information about how the local and global forcings

The Northern Gulf of Mexico During OAE2 and the Relationship Between Water Depth and Black Shale Development

NASA Astrophysics Data System (ADS)

Lowery, Christopher M.; Cunningham, Robert; Barrie, Craig D.; Bralower, Timothy; Snedden, John W.

2017-12-01

Despite their name, Oceanic Anoxic Events (OAEs) are not periods of uniform anoxia and black shale deposition in ancient oceans. Shelf environments account for the majority of productivity and organic carbon burial in the modern ocean, and this was likely true in the Cretaceous as well. However, it is unlikely that the mechanisms for such an increase were uniform across all shelf environments. Some, like the northwest margin of Africa, were characterized by strong upwelling, but what might drive enhanced productivity on shelves not geographically suited for upwelling? To address this, we use micropaleontology, carbon isotopes, and sedimentology to present the first record of Oceanic Anoxic Event 2 (OAE2) from the northern Gulf of Mexico shelf. Here OAE2 occurred during the deposition of the well-oxygenated, inner neritic/lower estuarine Lower Tuscaloosa Sandstone. The overlying organic-rich oxygen-poor Marine Tuscaloosa Shale is entirely Turonian in age. We trace organic matter enrichment from the Spinks Core into the deepwater Gulf of Mexico, where wireline log calculations and public geochemical data indicate organic enrichment and anoxia throughout the Cenomanian-Turonian boundary interval. Redox change and organic matter preservation across the Gulf of Mexico shelf were driven by sea level rise prior to the early Turonian highstand, which caused the advection of nutrient-rich, oxygen-poor waters onto the shelf. This results in organic matter mass accumulation rates 1-2 orders of magnitude lower than upwelling sites like the NW African margin, but it likely occurred over a much larger geographic area, suggesting that sea level rise was an important component of the overall increase in carbon burial during OAE2.

Installation of a Rudist Biostrome after the Late Aptian - Early Albian OAE1B (mural Formation, Southeastern Arizona)

NASA Astrophysics Data System (ADS)

Godet, A.; Helfrich-Dennis, M. M.; Suarez, M. B.

2015-12-01

Mesozoic climate change has been extensively studied in the Tethys, while their expression in the proto Gulf of Mexico can still be precised, especially for the time period straddling the Aptian-Albian boundary. During this time period, significant climatic events may correlate between the proto-Atlantic and the Tethys, amongst which the Oceanic Anoxic Event 1b that corresponds to a period of marine anoxia across this stage boundary. We hypothesized that this event may have impacted the shallow-marine carbonate factory that is now preserved near the town of Bisbee (Mule Mountains, southern Arizona). This sedimentary succession has been chosen because it documents a switch from a siliclastic- to carbonate-dominated sedimentation during the targeted time interval. Using carbon isotope chemostratigraphy, we were able to refine the stratigraphic framework of the Mural Formation, which was previously based on benthic organisms such as rudist bivalves and orbitolinids, such as Mesorbitolina texana. The OAE1b has been identified based on its peculiar δ13C signature supported by biostratigraphic data. Concurrently, microfacies analysis helped in reconstructing variations in sea levels. In southern Arizona, the OAE1b equivalent belongs to a third-order transgressive systems tract, and extends into the following highstand systems track. The maximum flooding surface is defined within a thick rudist biostrome with chondrodonts. It thus seems that the OAE1b did not strongly affected the carbonate factory in this region of the proto Gulf of Mexico. As a conclusion, limestone rocks now preserved in southeastern Arizona were deposited during the Late Aptian to Early Albian time period, during which the OAE1b developed. This paleoceanographic perturbation is expressed in the sedimentary record by its unique carbon isotope signature, with no significant impact on benthic ecosystems.

The OAE1a in Cuchía (Early Aptian, Spain): C and O geochemistry and global correlation

NASA Astrophysics Data System (ADS)

García-Mondéjar, Joaquín; Fernández-Mendiola, Pedro A.; Owen, Hugh G.

2015-12-01

C-isotopes, TOC and O geochemical data from the lower Aptian Cuchía section in the western Basque-Cantabrian basin (BCB) allow an accurate delimitation of the OAE1a-equivalent and its geochemical Menegattís segments, a detailed δ13Ccarb correlation with regional and interregional sections, and a high-resolution construction of TOC and bulk-rock δ18Ocarb curves and their interpretation. The δ13Ccarb values range from -2‰ and +4‰ (VPDB). They agree with previous data from the eastern BCB sections (Aralar) confirming the ammonite age of the OAE1a in the Basque-Cantabrian basin: Deshayesites forbesi, Deshayesites deshayesi, and Deshayesites deshayesi-Dufrenoyia furcata transition Zones. Interregional δ13Ccarb correlation with pelagic (Cismon, Italy, and Mid-Pacific Mountains, DSDP Site 463) and neritic (Roquefort-La Bédoule, France) core sections, reveals a common profile of a wide negative excursion characteristic of the OAE1a. It consists of a double trough separated by a flat relative maximum, with two negative spikes in the upper trough of neritic sections. TOC absolute values range from 0.12% to 1.37%. Segments of the TOC curve with persistent low values closely correspond with descending segments of the δ13Ccarb curve, and are attributed to lesser organic productivity in the BCB. Detailed bulk-rock δ18Ocarb data (-5.71‰ to -1.05 ‰ PDB) and variation curve show two main positive O-isotope shifts and three minor positive inflections, within a general negative trend characteristic of the OAE1a. The two major positive shifts correspond to both shallowing upwards sequences and the lowermost can be related to a eustatic sea level fall. Independent interregional correlation of the O-isotope shifts with C-isotopes supports their interpretation as punctuating colder events within a general warming trend.

Exploiting Degrees of Inflectional Ambiguity: Stem Form and the Time Course of Morphological Processing

ERIC Educational Resources Information Center

Jarvikivi, Juhani; Pyykkonen, Pirita; Niemi, Jussi

2009-01-01

The authors compared sublexical and supralexical approaches to morphological processing with unambiguous and ambiguous inflected words and words with ambiguous stems in 3 masked and unmasked priming experiments in Finnish. Experiment 1 showed equal facilitation for all prime types with a short 60-ms stimulus onset asynchrony (SOA) but significant…

Efficacy of Distortion Product Oto-Acoustic Emission (OAE)/Auditory Brainstem Evoked Response (ABR) Protocols in Universal Neonatal Hearing Screening and Detecting Hearing Loss in Children <2 Years of Age.

PubMed

Mishra, Girish; Sharma, Yojana; Mehta, Kanishk; Patel, Gunjan

2013-04-01

Deafness is commonest curable childhood handicap. Most remedies and programmes don't address this issue at childhood level leading to detrimental impact on development of newborns. Aims and objectives are (A) screen all newborns for deafness and detect prevalence of deafness in children less than 2 years of age. and (B) assess efficacy of multi-staged OAE/ABR protocol for hearing screening. Non-randomized, prospective study from August 2008 to August 2011. All infants underwent a series of oto-acoustic emission (OAE) and final confirmatory auditory brainstem evoked response (ABR) audiometry. Finally, out of 1,101 children, 1,069 children passed the test while 12 children had impaired hearing after final testing, confirmed by ABR. Positive predictive value of OAE after multiple test increased to 100 %. OAE-ABR test series is effective in screening neonates and multiple tests reduce economic burden. High risk screening will miss nearly 50 % deaf children, thus universal screening is indispensable in picking early deafness.

A new sediment core from the early Aptian OAE1a: the Cau section (Prebetic Zone, Spain)

NASA Astrophysics Data System (ADS)

Alejandro Ruiz-Ortiz, Pedro; Castro, José Manuel; de Gea, Ginés A.; Jarvis, Ian; Loeser, Hannes; Molina, José Miguel; Nieto, Luis Miguel; Pancost, Richard; Quijano, María Luisa; Reolid, Matías; Skelton, Peter; Weissert, Helmut

2016-04-01

The occurrence of time intervals of enhanced deposition of organic matter (OM) during the Cretaceous, defined as Oceanic Anoxic Events (OAE), reflect abrupt changes in global carbon cycling. The exemplary Aptian OAE1a (120 Ma), is recorded in all the main ocean basins and associated with massive burial of OM in marine sediments [1]. OAE1a is concomitant with the 'nannoconid crisis', which represents a major biotic turnover [2], and also with widespread demise of carbonate platforms [1]. Much research has been done on the OAE1a from different sections in the world over the last decades, since the definition of the C-isotope stratigraphy of the event [3]. Notwithstanding, high-resolution studies across the entire event will be crucial to elucidate the precise timing and rates of the different environmental and biotic changes involved. In order to perform high-resolution studies, drill-cores can represent the best option. Previous cores with successful scientific results has been performed in two reference sections, the Cismon Apti-core [4], and more recently in La Bédoule [5]. Here we present a new drill-core from southern Spain, the Cau section core, drilled in the last quarter of 2015. The Cau section is located in the easternmost part of the Prebetic Zone (Betic Cordillera), which represents the platform deposits of the Southern Iberian Palaeomargin. The lower Aptian of the Cau section is represented by an hemipelagic unit (Almadich Formation, ca. 200 m thick), deposited in a highly subsiding sector of a tilted block, located in the distal parts of the Prebetic Platform. Previous studies of the early Aptian of the Cau section have focused on the stratigraphy, bioevents, C-isotope stratigraphy, and organic and elemental geochemistry [6], [7], among others. A recent study on the Cau section based on biomarkers has presented a detailed record of the PCO2, [8]. All these studies reveal that the Cau section represents an excellent site to investigate the OAE1a, based

Testing the sulfate-phosphorous hypothesis for initiation of the early Aptian OAE1a

NASA Astrophysics Data System (ADS)

Mills, J. V.; Gomes, M. L.; Sageman, B. B.; Hurtgen, M. T.

2012-12-01

Oceanic anoxic events (OAEs) were short-lived (<1-myr) episodes of widespread marine organic carbon burial and anoxia that occurred during the Mesozoic. Several hypotheses have been proposed to explain these intervals of increased organic carbon production and preservation, yet none have satisfactorily accounted for the short-term character and widespread effects of the events. Some recent work has focused on the role of sulfur in the initiation/termination mechanism of these events, specifically the potential impact of a large increase in marine sulfate levels upon a very low sulfate background. Previous authors have suggested that a large pulse of volcanic-derived sulfur could have initiated widespread anoxia through a positive feedback cycle of enhanced phosphorous recycling and increased primary production. In this model, a sudden pulse of sulfur upon a low sulfate background impacts the biogeochemical cycles of sulfur and iron, leading to an escalation in phosphorous (P) release from sediments during organic matter degradation. The resulting sulfate-P feedback cycle, recognized in modern lake systems, continues until sulfate levels are drawn down by pyrite burial, thus ending the anoxic event. To test this hypothesis, we examine sulfur and carbon isotopes through the early Aptian OAE1a (~120 Ma) from Resolution Guyot in the Mid-Pacific Mountains (ODP Site 866). We present sulfur isotope records of carbonate-associated sulfate (CAS), which provide a higher resolution record than other sulfate records (e.g. marine barites), to infer how sulfate concentrations changed through the event. A decrease of ~5 permil in the CAS sulfur isotope composition through the event suggests either that massive volcanism delivered 34S-depleted sulfate to the oceans and/or that large-scale evaporite (calcium sulfate) deposition forced a reduction in marine sulfate levels and associated rates of pyrite burial. These results will be discussed within the context of evolving δ34

Response of proto-North Atlantic carbonate-platform ecosystems to OAE1a-related stressors

NASA Astrophysics Data System (ADS)

Huck, Stefan; Stein, Melody; Immenhauser, Adrian; Skelton, Peter W.; Christ, Nicolas; Föllmi, Karl B.; Heimhofer, Ulrich

2014-11-01

Integrated biostratigraphic-chemostratigraphic studies provide evidence that the proto-North Atlantic realm witnessed major changes in carbonate platform production in the run-up of the Early Aptian oceanic anoxic event (OAE) 1a. Whereas pervasive growth of Lithocodium microencrusters represents an early harbinger of OAE1a-related environmental perturbation, the subsequent replacement of oligotrophic rudist-coral-nerineid by mesotrophic orbitolinid-oyster communities was clearly associated with the event itself. In order to test the supra-regional relevance of this major community replacement, two shallow-water sections in the southern Lusitanian Basin (Portugal) are investigated by means of geochemistry (carbon and oxygen isotopes), cement petrography and detailed sedimentological analysis. The focus is on a regional, prominent discontinuity surface (S4) at the transition between oligotrophic and mesotrophic carbonate platform production, which might indicate that the major biotic change could have been associated with a phase of non-sedimentation and possibly erosion. The studied sections (São Julião, Crismina) provide evidence that the major Early Aptian biotic turnover was preceded by numerous subordinate but significant changes in platform ecology, which mirrored a series of progressive short-term environmental changes in the course of OAE1. Several transient mass occurrences of orbitolinids indicate repeated phases of ecological stress arguably due to enhanced nutrient input and deepening. Small-scale sea-level changes at parasequence level below the major discontinuity surface are revealed by alternations of rudist assemblages dominated by clinger or recumbent forms as well as intercalated hardground and subaerial exposure stages. Expanded phases of subaerial exposure, however, can be largely ruled out following the geochemical and cement-petrographic data presented here. Enhanced continent-derived siliciclastic input characterising the lower orbitolinid

Are ambiguity aversion and ambiguity intolerance identical? A neuroeconomics investigation

PubMed Central

Tanaka, Yusuke; Fujino, Junya; Ideno, Takashi; Okubo, Shigetaka; Takemura, Kazuhisa; Miyata, Jun; Kawada, Ryosaku; Fujimoto, Shinsuke; Kubota, Manabu; Sasamoto, Akihiko; Hirose, Kimito; Takeuchi, Hideaki; Fukuyama, Hidenao; Murai, Toshiya; Takahashi, Hidehiko

2015-01-01

In recent years, there has been growing interest in understanding a person's reaction to ambiguous situations, and two similar constructs related to ambiguity, “ambiguity aversion” and “ambiguity intolerance,” are defined in different disciplines. In the field of economic decision-making research, “ambiguity aversion” represents a preference for known risks relative to unknown risks. On the other hand, in clinical psychology, “ambiguity intolerance” describes the tendency to perceive ambiguous situations as undesirable. However, it remains unclear whether these two notions derived from different disciplines are identical or not. To clarify this issue, we combined an economic task, psychological questionnaires, and voxel-based morphometry (VBM) of structural brain magnetic resonance imaging (MRI) in a sample of healthy volunteers. The individual ambiguity aversion tendency parameter, as measured by our economic task, was negatively correlated with agreeableness scores on the self-reported version of the Revised NEO Personality Inventory. However, it was not correlated with scores of discomfort with ambiguity, one of the subscales of the Need for Closure Scale. Furthermore, the ambiguity aversion tendency parameter was negatively correlated with gray matter (GM) volume of areas in the lateral prefrontal cortex and parietal cortex, whereas ambiguity intolerance was not correlated with GM volume in any region. Our results suggest that ambiguity aversion, described in decision theory, may not necessarily be identical to ambiguity intolerance, referred to in clinical psychology. Cautious applications of decision theory to clinical neuropsychiatry are recommended. PMID:25698984

Are ambiguity aversion and ambiguity intolerance identical? A neuroeconomics investigation.

PubMed

Tanaka, Yusuke; Fujino, Junya; Ideno, Takashi; Okubo, Shigetaka; Takemura, Kazuhisa; Miyata, Jun; Kawada, Ryosaku; Fujimoto, Shinsuke; Kubota, Manabu; Sasamoto, Akihiko; Hirose, Kimito; Takeuchi, Hideaki; Fukuyama, Hidenao; Murai, Toshiya; Takahashi, Hidehiko

2014-01-01

In recent years, there has been growing interest in understanding a person's reaction to ambiguous situations, and two similar constructs related to ambiguity, "ambiguity aversion" and "ambiguity intolerance," are defined in different disciplines. In the field of economic decision-making research, "ambiguity aversion" represents a preference for known risks relative to unknown risks. On the other hand, in clinical psychology, "ambiguity intolerance" describes the tendency to perceive ambiguous situations as undesirable. However, it remains unclear whether these two notions derived from different disciplines are identical or not. To clarify this issue, we combined an economic task, psychological questionnaires, and voxel-based morphometry (VBM) of structural brain magnetic resonance imaging (MRI) in a sample of healthy volunteers. The individual ambiguity aversion tendency parameter, as measured by our economic task, was negatively correlated with agreeableness scores on the self-reported version of the Revised NEO Personality Inventory. However, it was not correlated with scores of discomfort with ambiguity, one of the subscales of the Need for Closure Scale. Furthermore, the ambiguity aversion tendency parameter was negatively correlated with gray matter (GM) volume of areas in the lateral prefrontal cortex and parietal cortex, whereas ambiguity intolerance was not correlated with GM volume in any region. Our results suggest that ambiguity aversion, described in decision theory, may not necessarily be identical to ambiguity intolerance, referred to in clinical psychology. Cautious applications of decision theory to clinical neuropsychiatry are recommended.

Treatment decisions under ambiguity.

PubMed

Berger, Loïc; Bleichrodt, Han; Eeckhoudt, Louis

2013-05-01

Many health risks are ambiguous in the sense that reliable and credible information about these risks is unavailable. In health economics, ambiguity is usually handled through sensitivity analysis, which implicitly assumes that people are neutral towards ambiguity. However, empirical evidence suggests that people are averse to ambiguity and react strongly to it. This paper studies the effects of ambiguity aversion on two classical medical decision problems. If there is ambiguity regarding the diagnosis of a patient, ambiguity aversion increases the decision maker's propensity to opt for treatment. On the other hand, in the case of ambiguity regarding the effects of treatment, ambiguity aversion leads to a reduction in the propensity to choose treatment. Copyright © 2013 Elsevier B.V. All rights reserved.

Image Ambiguity and Fluency

PubMed Central

Jakesch, Martina; Leder, Helmut; Forster, Michael

2013-01-01

Ambiguity is often associated with negative affective responses, and enjoying ambiguity seems restricted to only a few situations, such as experiencing art. Nevertheless, theories of judgment formation, especially the “processing fluency account”, suggest that easy-to-process (non-ambiguous) stimuli are processed faster and are therefore preferred to (ambiguous) stimuli, which are hard to process. In a series of six experiments, we investigated these contrasting approaches by manipulating fluency (presentation duration: 10ms, 50ms, 100ms, 500ms, 1000ms) and testing effects of ambiguity (ambiguous versus non-ambiguous pictures of paintings) on classification performance (Part A; speed and accuracy) and aesthetic appreciation (Part B; liking and interest). As indicated by signal detection analyses, classification accuracy increased with presentation duration (Exp. 1a), but we found no effects of ambiguity on classification speed (Exp. 1b). Fifty percent of the participants were able to successfully classify ambiguous content at a presentation duration of 100 ms, and at 500ms even 75% performed above chance level. Ambiguous artworks were found more interesting (in conditions 50ms to 1000ms) and were preferred over non-ambiguous stimuli at 500ms and 1000ms (Exp. 2a - 2c, 3). Importantly, ambiguous images were nonetheless rated significantly harder to process as non-ambiguous images. These results suggest that ambiguity is an essential ingredient in art appreciation even though or maybe because it is harder to process. PMID:24040172

Astronomical tuning of black cherts in the Cenomanian Scaglia Bianca as precursors of the Bonarelli level (OAE2) at Furlo, Italy

NASA Astrophysics Data System (ADS)

Batenburg, S. J.; Montanari, A.; Sprovieri, M.; Hilgen, F. J.; Coccioni, R.; Gale, A. S.

2012-04-01

chert deposition, as well as the onset of the oceanic anoxic event itself, is related to eccentricity maxima. The stable 405-kyr periodicity of eccentricity is readily discernible in the data records and can be used for tuning to the astronomical solution (Laskar et al. 2011). A total of five and a half 405-kyr cycles can be identified below the Bonarelli level, which itself comprises a 405-kyr cycle. This cyclostratigraphy can potentially be anchored to the absolute time scale by using the newly determined Cenomanian-Turonian boundary age of 93.9 ± 0.15 Ma, which is based on intercalibration of astrochronological and radioisotopic data for the Cenomanian-Turonian boundary interval near the GSSP in Colorado, USA (Meyers et al., 2012). Correlation to the orbitally tuned Turonian interval of the nearby Gubbio and Contessa sections in Italy (De Vleeschouwer et al., this session) allows the construction of an anchored astronomical time scale for the Cenomanian-Turonian interval of > 5 Ma. Herbert, T. D., and A. G. Fischer. 1986. "Milankovitch climatic origin of mid-Cretaceous black shale rhythms in central Italy." Nature 321 (19): 739-743. Lanci, L., G. Muttoni, and E. Erba. 2010. "Astronomical tuning of the Cenomanian Scaglia Bianca Formation at Furlo, Italy." Earth and Planetary Science Letters. Laskar, J., A. Fienga, M. Gastineau, and H. Manche. 2011. "La2010: A new orbital solution for the long term motion of the Earth." Astronomy and Astrophysics arXiv:1103.1084v1. Mitchell, Ross N., David M. Bice, Alessandro Montanari, Laura C. Cleaveland, Keith T. Christianson, Rodolfo Coccioni, and Linda A. Hinnov. 2008. "Oceanic anoxic cycles? Orbital prelude to the Bonarelli Level (OAE 2)." Earth and Planetary Science Letters 267: 1-16. Trabucho Alexandre, J., E. Tuenter, G. A Henstra, K. J van der Zwan, R. S.W van de Wal, H. A Dijkstra, and P. L de Boer. 2010. "The mid-Cretaceous North Atlantic nutrient trap: Black shales and OAEs." Paleoceanography 25 (4).

Measuring higher order ambiguity preferences.

PubMed

Baillon, Aurélien; Schlesinger, Harris; van de Kuilen, Gijs

2018-01-01

We report the results from an experiment designed to measure attitudes towards ambiguity beyond ambiguity aversion. In particular, we implement recently-proposed model-free preference conditions of ambiguity prudence and ambiguity temperance. Ambiguity prudence has been shown to play an important role in precautionary behavior and the mere presence of ambiguity averse agents in markets. We observe that the majority of individuals' decisions are consistent with ambiguity aversion, ambiguity prudence and ambiguity temperance. This finding confirms the prediction of many popular (specifications of) ambiguity models and has important implications for models of prevention behavior.

Opposite Influence of Perceptual Memory on Initial and Prolonged Perception of Sensory Ambiguity

PubMed Central

de Jong, Maartje Cathelijne; Knapen, Tomas; van Ee, Raymond

2012-01-01

Observers continually make unconscious inferences about the state of the world based on ambiguous sensory information. This process of perceptual decision-making may be optimized by learning from experience. We investigated the influence of previous perceptual experience on the interpretation of ambiguous visual information. Observers were pre-exposed to a perceptually stabilized sequence of an ambiguous structure-from-motion stimulus by means of intermittent presentation. At the subsequent re-appearance of the same ambiguous stimulus perception was initially biased toward the previously stabilized perceptual interpretation. However, prolonged viewing revealed a bias toward the alternative perceptual interpretation. The prevalence of the alternative percept during ongoing viewing was largely due to increased durations of this percept, as there was no reliable decrease in the durations of the pre-exposed percept. Moreover, the duration of the alternative percept was modulated by the specific characteristics of the pre-exposure, whereas the durations of the pre-exposed percept were not. The increase in duration of the alternative percept was larger when the pre-exposure had lasted longer and was larger after ambiguous pre-exposure than after unambiguous pre-exposure. Using a binocular rivalry stimulus we found analogous perceptual biases, while pre-exposure did not affect eye-bias. We conclude that previously perceived interpretations dominate at the onset of ambiguous sensory information, whereas alternative interpretations dominate prolonged viewing. Thus, at first instance ambiguous information seems to be judged using familiar percepts, while re-evaluation later on allows for alternative interpretations. PMID:22295095

Characterization of the Lower Aptian Oceanic Anoxic Event (OAE) 1a in the Eastern Iberian Chain (Maestrat Basin, E Spain) by Means of Ammonite Biostratigraphy

NASA Astrophysics Data System (ADS)

Moreno-Bedmar, J. A.; Company, M.; Bover-Arnal, T.; Delanoy, G.; Martinez, R.; Grauges, A.; Salas, R.

2008-05-01

Oceanic Anoxic Event 1a (OAE1a) is now generally recognized to correlate with the lower part of the Leupoldina cabri planktonic foraminifer Zone. Unfortunately, the calibration of this zone against the standard ammonite scale has remained uncertain. Our recent high-resolution geochemical study (Carbon-isotope) of Lower Aptian sequences in the Iberian Chain of eastern Spain (Moreno-Bedmar et al., in prep) was used as proxy to further characterize OAE 1a. The sequence provides additional ammonite biostratigraphic data that permit correlation of the ammonite zonation with the isotopic signature of OAE1a. That interval includes specimens we identified with affinity for species of Roloboceras and Megatyloceras in the same beds that contain species of Deshayesites forbesi Casey, and Deshayesites gr. euglyphus/spathi, which are characteristic of the Deshayesites weissi Zone. Our results also indicate that D. deshayesi (d'Orbigny), the nominate taxon which marks the base of the superjacent Zone, first occurs a few meters above the geochemical signature corresponding to OAE 1a. Our isotopic data correlated with the ammonite occurrences are in further agreement with Roloboceras beds in England (Casey, 1961a, b; Casey et al., 1998) that are correlational with the Boreal Deshayesites forbesi Zone, which is coeval with the Mediterranean Deshayesites weissi Zone. Similarly, in the Cassis-La Bédoule area (SE France) the OAE 1a interval also corresponds to the Roloboceras beds, but they have been assigned to the Deshayesites deshayesi biozone (Ropolo et al., 2000; 2006). Here we argue that specimens attributed to D. deshayesi (d'Orbigny) and D. dechyi (Papp) from the Roloboceras levels (Ropolo et al., 2006) can be reinterpreted as belonging to D. forbesi, characteristic species of Deshayesites weissi Zone. Stratigraphic data from Roloboceras beds in le Teil region (Ardech patform, SE France) also reveal the presence of Deshayesites consobrinus (d'Orbigny) and Deshayesites gr

Gamma activity modulated by naming of ambiguous and unambiguous images: intracranial recording

PubMed Central

Cho-Hisamoto, Yoshimi; Kojima, Katsuaki; Brown, Erik C; Matsuzaki, Naoyuki; Asano, Eishi

2014-01-01

OBJECTIVE Humans sometimes need to recognize objects based on vague and ambiguous silhouettes. Recognition of such images may require an intuitive guess. We determined the spatial-temporal characteristics of intracranially-recorded gamma activity (at 50–120 Hz) augmented differentially by naming of ambiguous and unambiguous images. METHODS We studied ten patients who underwent epilepsy surgery. Ambiguous and unambiguous images were presented during extraoperative electrocorticography recording, and patients were instructed to overtly name the object as it is first perceived. RESULTS Both naming tasks were commonly associated with gamma-augmentation sequentially involving the occipital and occipital-temporal regions, bilaterally, within 200 ms after the onset of image presentation. Naming of ambiguous images elicited gamma-augmentation specifically involving portions of the inferior-frontal, orbitofrontal, and inferior-parietal regions at 400 ms and after. Unambiguous images were associated with more intense gamma-augmentation in portions of the occipital and occipital-temporal regions. CONCLUSIONS Frontal-parietal gamma-augmentation specific to ambiguous images may reflect the additional cortical processing involved in exerting intuitive guess. Occipital gamma-augmentation enhanced during naming of unambiguous images can be explained by visual processing of stimuli with richer detail. SIGNIFICANCE Our results support the theoretical model that guessing processes in visual domain occur following the accumulation of sensory evidence resulting from the bottom-up processing in the occipital-temporal visual pathways. PMID:24815577

Detrital and oceanic dysoxia influence on OAE2 sediment geochemistry from Tarfaya, SW Morocco

NASA Astrophysics Data System (ADS)

Turgeon, S. C.; Kolonic, S.; Brumsack, H.-J.; Wagner, T.

2003-04-01

The Cretaceous "greenhouse" world's stratigraphic record is punctuated by several important organic-rich intervals representing quasi-global "Oceanic Anoxic Events" (OAEs). This study focuses on sediments from Tarfaya in SW Morocco deposited during the Cenomanian-Turonian Boundary Event (CTBE or OAE2 at 93.5 Ma). These sediments consist of distinctly laminated, carbonate-rich black shales alternating with lighter coloured structureless intervals and sporadic chert lenses. Sediments from three sites representing proximal to distal settings were studied. Samples were analysed for Ctot, Corg, Stot, as well as several major-, minor- and trace elements using XRF and ICP-MS. These sediments are characterised by high Corg, Stot, and CaCO3 contents and consist of a simple two component mixing system ("average shale"-CaCO3). Major element concentrations are low, except for Ca and P, owing in part to the carbonate dilution effect. Most elements plot along "average shale" lines. Elements such as Si, Ti, Fe, K, Rb, and Zr show positive relationships with Al2O3, pointing to homogeneous source area material. Several Al-normalised elements (As, Ba, Cr, Cu, Ni, Sr, U, V, Y, Zn), many of them redox-sensitive or sulphide-residing, are enriched in the sediments indicating an oxygen-depleted environment and potential availability of hydrogen sulfide in the water column at the time of deposition. High Zn concentrations suggest increased submarine volcanism and/or hydrothermal activity during this time interval. High Ba concentrations are possibly indicative of high regional paleoproductivity, which is further supported by the elevated P concentrations hinting at nutrient availability. Basinward trends in the geochemical distribution of some elements are apparent and probably reflect the decreasing influence of terrestrial sediments away from the shoreline.

The Ethics of Ambiguity

PubMed Central

2016-01-01

Understanding and embracing uncertainty are critical for effective teacher–learner relationships as well as for shared decision-making in the physician–patient relationship. However, ambiguity has not been given serious consideration in either the undergraduate or graduate medical curricula or in the role it plays in patient-centered care. In this article, the author examines the ethics of ambiguity and argues for a pedagogy that includes education in the importance of, and tolerance of, ambiguity that is inherent in medical education and practice. Common threads running through the ethics of ambiguity are the virtue of respect, and the development of a culture of respect is required for the successful understanding and implementation of a pedagogy of ambiguity. PMID:28725771

Don't panic: interpretation bias is predictive of new onsets of panic disorder.

PubMed

Woud, Marcella L; Zhang, Xiao Chi; Becker, Eni S; McNally, Richard J; Margraf, Jürgen

2014-01-01

Psychological models of panic disorder postulate that interpretation of ambiguous material as threatening is an important maintaining factor for the disorder. However, demonstrations of whether such a bias predicts onset of panic disorder are missing. In the present study, we used data from the Dresden Prediction Study, in which a epidemiologic sample of young German women was tested at two time points approximately 17 months apart, allowing the study of biased interpretation as a potential risk factor. At time point one, participants completed an Interpretation Questionnaire including two types of ambiguous scenarios: panic-related and general threat-related. Analyses revealed that a panic-related interpretation bias predicted onset of panic disorder, even after controlling for two established risk factors: anxiety sensitivity and fear of bodily sensations. This is the first prospective study demonstrating the incremental validity of interpretation bias as a predictor of panic disorder onset. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chemostratigraphy at DSDP Sites 386 (Bermuda Rise) and 144 (Demerara Rise), Implications for Euxinic Conditions During OAE-2

NASA Astrophysics Data System (ADS)

Horst, P. A.; Maurrasse, F. J.; Sinninghe-Damsté, J. S.; Sandler, A.

2008-05-01

Chemostratigraphic studies of DSDP Site 386 on the Bermuda Rise and Site 144 on the Demerara Rise indicate that euxinic conditions developed at these deep-water sites during the time interval that corresponds to Oceanic Anoxic Event 2 (OAE 2). The data show a large increase in Fe/Al ratios, and dispersed pyrite aggregates (Site 386 Core 43, Section 3). Such findings at these deep oceanic sites are compatible with earlier studies showing that sediments in euxinic settings display increases in Fe/Al ratios due to the scavenging of dissolved Fe, and is also in agreement with previous Pr/Ph ratio of <1 (Simoneit, 1979). This study further shows that OM, previously believed to show bimodal distribution, which was used to argue in support of turbidity currents at Site 386 as transport mechanism for some of the OM, is predominantly derived from marine phytoplankton and cyanobacteria showing low thermal stress, supporting in situ derivation. Elemental analyses at Site 386 also show that relatively high Sr/CaO ratios are present before and after OAE 2, indicating an increased contribution of biogenic carbonates, but not during the C/T boundary event. When Cr is plotted against Al2O3 in conjunction with a solid line representing the Cr/Al2O3 ratio in average shale, half of the samples fall above and half fall below this line. The values that plot above this line are all from Cores 47, 44, 43, and 42, which contain higher TOC. Their strong Cr enrichment with respect to the average shale can be indicative of an algal source of the OM, as this biota preferentially concentrates Cr. Competitive exclusion due to dominance of opportunistic prokaryotic blooms in combination with oxygen depletion can be invoked to explain the conditions that developed and were unfavorable to most other organisms throughout the water column during OAE 2. Sediments from DSDP Site 144 also reveal increased molecular fossils indicative of green sulfur bacteria, which are further characteristic of euxinic

The spatial-temporal ambiguity in auroral modeling

NASA Technical Reports Server (NTRS)

Rees, M. H.; Roble, R. G.; Kopp, J.; Abreu, V. J.; Rusch, D. W.; Brace, L. H.; Brinton, H. C.; Hoffman, R. A.; Heelis, R. A.; Kayser, D. C.

1980-01-01

The paper examines the time-dependent models of the aurora which show that various ionospheric parameters respond to the onset of auroral ionization with different time histories. A pass of the Atmosphere Explorer C satellite over Poker Flat, Alaska, and ground based photometric and photographic observations have been used to resolve the time-space ambiguity of a specific auroral event. The density of the O(+), NO(+), O2(+), and N2(+) ions, the electron density, and the electron temperature observed at 280 km altitude in a 50 km wide segment of an auroral arc are predicted by the model if particle precipitation into the region commenced about 11 min prior to the overpass.

Ambiguity aversion in schizophrenia: An fMRI study of decision-making under risk and ambiguity.

PubMed

Fujino, Junya; Hirose, Kimito; Tei, Shisei; Kawada, Ryosaku; Tsurumi, Kosuke; Matsukawa, Noriko; Miyata, Jun; Sugihara, Genichi; Yoshihara, Yujiro; Ideno, Takashi; Aso, Toshihiko; Takemura, Kazuhisa; Fukuyama, Hidenao; Murai, Toshiya; Takahashi, Hidehiko

2016-12-01

When making decisions in everyday life, we often have to choose between uncertain outcomes. Economic studies have demonstrated that healthy people tend to prefer options with known probabilities (risk) than those with unknown probabilities (ambiguity), which is referred to as "ambiguity aversion." However, it remains unclear how patients with schizophrenia behave under ambiguity, despite growing evidence of their altered decision-making under uncertainty. In this study, combining economic tools and functional magnetic resonance imaging (fMRI), we assessed the attitudes toward risk/ambiguity and investigated the neural correlates during decision-making under risk/ambiguity in schizophrenia. Although no significant difference in attitudes under risk was observed, patients with schizophrenia chose ambiguity significantly more often than the healthy controls. Attitudes under risk and ambiguity did not correlate across patients with schizophrenia. Furthermore, unlike in the healthy controls, activation of the left lateral orbitofrontal cortex was not increased during decision-making under ambiguity compared to under risk in schizophrenia. These results suggest that ambiguity aversion, a well-established subjective bias, is attenuated in patients with schizophrenia, highlighting the need to distinguish between risk and ambiguity when assessing decision-making under these situations. Our findings, comprising important clinical implications, contribute to improved understanding of the mechanisms underlying altered decision-making in patients with schizophrenia. Copyright © 2016 Elsevier B.V. All rights reserved.

Lateralization of noise-burst trains based on onset and ongoing interaural delays.

PubMed

Freyman, Richard L; Balakrishnan, Uma; Zurek, Patrick M

2010-07-01

The lateralization of 250-ms trains of brief noise bursts was measured using an acoustic pointing technique. Stimuli were designed to assess the contribution of the interaural time delay (ITD) of the onset binaural burst relative to that of the ITDs in the ongoing part of the train. Lateralization was measured by listeners' adjustments of the ITD of a pointer stimulus, a 50-ms burst of noise, to match the lateral position of the target train. Results confirmed previous reports of lateralization dominance by the onset burst under conditions in which the train is composed of frozen tokens and the ongoing part contains multiple ambiguous interaural delays. In contrast, lateralization of ongoing trains in which fresh noise tokens were used for each set of two alternating (left-leading/right-leading) binaural pairs followed the ITD of the first pair in each set, regardless of the ITD of the onset burst of the entire stimulus and even when the onset burst was removed by gradual gating. This clear lateralization of a long-duration stimulus with ambiguous interaural delay cues suggests precedence mechanisms that involve not only the interaural cues at the beginning of a sound, but also the pattern of cues within an ongoing sound.

Changes in CO2 during Ocean Anoxic Event 1d indicate similarities to other carbon cycle perturbations

NASA Astrophysics Data System (ADS)

Richey, Jon D.; Upchurch, Garland R.; Montañez, Isabel P.; Lomax, Barry H.; Suarez, Marina B.; Crout, Neil M. J.; Joeckel, R. M.; Ludvigson, Greg A.; Smith, Jon J.

2018-06-01

Past greenhouse intervals of the Mesozoic were repeatedly punctuated by Ocean Anoxic Events (OAEs), major perturbations to the global carbon cycle and abrupt climate changes that may serve as relevant analogs for Earth's greenhouse gas-forced climate future. The key to better understanding these transient climate disruptions and possible CO2-forced tipping-points resides in high-resolution, precise, and accurate estimates of atmospheric CO2 for individual OAEs. Here we present a high-temporal resolution, multi-proxy pCO2 reconstruction for the onset of mid-Cretaceous (Albian-Cenomanian Boundary) OAE1d. Coupling of pCO2 estimates with carbon isotopic compositions (δ13C) of charcoal, vitrain, and cuticle from the Rose Creek Pit (RCP), Nebraska, reveals complex phasing, including a lag between the well-documented negative δ13C excursion defining the onset of OAE1d and the CO2 increase. This lag indicates that increased CO2 or other C-based greenhouse gases may not have been the primary cause of the negative excursion. Our study reveals a pCO2 increase within the interval of the negative δ13C excursion, reaching a maximum of up to ∼840 ppm (95% confidence interval -307 ppm/+167 ppm) toward its end. The reconstructed magnitude of CO2 increase (∼357 ppm) is similar to that of Late Cretaceous OAE2 but of smaller magnitude than that of other major carbon cycle perturbations of the Mesozoic assessed via stomatal methods (e.g., the Toarcian OAE [TOAE], Triassic-Jurassic boundary event, Cretaceous-Paleogene Boundary event). Furthermore, our results indicate a possible shared causal or developmental mechanism with OAE1a and the TOAE.

Ambiguity Aversion in Rhesus Macaques

PubMed Central

Hayden, Benjamin Y.; Heilbronner, Sarah R.; Platt, Michael L.

2010-01-01

People generally prefer risky options, which have fully specified outcome probabilities, to ambiguous options, which have unspecified probabilities. This preference, formalized in economics, is strong enough that people will reliably prefer a risky option to an ambiguous option with a greater expected value. Explanations for ambiguity aversion often invoke uniquely human faculties like language, self-justification, or a desire to avoid public embarrassment. Challenging these ideas, here we demonstrate that a preference for unambiguous options is shared with rhesus macaques. We trained four monkeys to choose between pairs of options that both offered explicitly cued probabilities of large and small juice outcomes. We then introduced occasional trials where one of the options was obscured and examined their resulting preferences; we ran humans in a parallel experiment on a nearly identical task. We found that monkeys reliably preferred risky options to ambiguous ones, even when this bias was costly, closely matching the behavior of humans in the analogous task. Notably, ambiguity aversion varied parametrically with the extent of ambiguity. As expected, ambiguity aversion gradually declined as monkeys learned the underlying probability distribution of rewards. These data indicate that ambiguity aversion reflects fundamental cognitive biases shared with other animals rather than uniquely human factors guiding decisions. PMID:20922060

Five-year-olds do not show ambiguity aversion in a risk and ambiguity task with physical objects.

PubMed

Li, Rosa; Roberts, Rachel C; Huettel, Scott A; Brannon, Elizabeth M

2017-07-01

Ambiguity aversion arises when a decision maker prefers risky gambles with known probabilities over equivalent ambiguous gambles with unknown probabilities. This phenomenon has been consistently observed in adults across a large body of empirical work. Evaluating ambiguity aversion in young children, however, has posed methodological challenges because probabilistic representations appropriate for adults might not be understood by young children. Here, we established a novel method for representing risk and ambiguity with physical objects that overcomes previous methodological limitations and allows us to measure ambiguity aversion in young children. We found that individual 5-year-olds exhibited consistent choice preferences and, as a group, exhibited no ambiguity aversion in a task that evokes ambiguity aversion in adults. Across individuals, 5-year-olds exhibited greater variance in ambiguity preferences compared with adults tested under similar conditions. This suggests that ambiguity aversion is absent during early childhood and emerges over the course of development. Copyright © 2017 Elsevier Inc. All rights reserved.

Determinants of translation ambiguity

PubMed Central

Degani, Tamar; Prior, Anat; Eddington, Chelsea M.; Arêas da Luz Fontes, Ana B.; Tokowicz, Natasha

2016-01-01

Ambiguity in translation is highly prevalent, and has consequences for second-language learning and for bilingual lexical processing. To better understand this phenomenon, the current study compared the determinants of translation ambiguity across four sets of translation norms from English to Spanish, Dutch, German and Hebrew. The number of translations an English word received was correlated across these different languages, and was also correlated with the number of senses the word has in English, demonstrating that translation ambiguity is partially determined by within-language semantic ambiguity. For semantically-ambiguous English words, the probability of the different translations in Spanish and Hebrew was predicted by the meaning-dominance structure in English, beyond the influence of other lexical and semantic factors, for bilinguals translating from their L1, and translating from their L2. These findings are consistent with models postulating direct access to meaning from L2 words for moderately-proficient bilinguals. PMID:27882188

Processing Coordination Ambiguity

ERIC Educational Resources Information Center

Engelhardt, Paul E.; Ferreira, Fernanda

2010-01-01

We examined temporarily ambiguous coordination structures such as "put the butter in the bowl and the pan on the towel." Minimal Attachment predicts that the ambiguous noun phrase "the pan" will be interpreted as a noun-phrase coordination structure because it is syntactically simpler than clausal coordination. Constraint-based…

Report of the first international workshop on onchocerciasis-associated epilepsy.

PubMed

Colebunders, Robert; Mandro, Michel; Njamnshi, Alfred K; Boussinesq, Michel; Hotterbeekx, An; Kamgno, Joseph; O'Neill, Sarah; Hopkins, Adrian; Suykerbuyk, Patrick; Basáñez, Maria-Gloria; Post, Rory J; Pedrique, Belén; Preux, Pierre-Marie; Stolk, Wilma A; Nutman, Thomas B; Idro, Richard

2018-03-22

Recently, several epidemiological studies performed in Onchocerca volvulus-endemic regions have suggested that onchocerciasis-associated epilepsy (OAE) may constitute an important but neglected public health problem in many countries where onchocerciasis is still endemic. On October 12-14 th 2017, the first international workshop on onchocerciasis-associated epilepsy (OAE) was held in Antwerp, Belgium. The workshop was attended by 79 participants from 20 different countries. Recent research findings strongly suggest that O. volvulus is an important contributor to epilepsy, particularly in meso- and hyperendemic areas for onchocerciasis. Infection with O. volvulus is associated with a spectrum of epileptic seizures, mainly generalised tonic-clonic seizures but also atonic neck seizures (nodding), and stunted growth. OAE is characterised by an onset of seizures between the ages of 3-18 years. Multidisciplinary working groups discussed topics such as how to 1) strengthen the evidence for an association between onchocerciasis and epilepsy, 2) determine the burden of disease caused by OAE, 3) prevent OAE, 4) improve the treatment/care for persons with OAE and affected families, 5) identify the pathophysiological mechanism of OAE, and 6) deal with misconceptions, stigma, discrimination and gender violence associated with OAE. An OAE Alliance was created to increase awareness about OAE and its public health importance, stimulate research and disseminate research findings, and create partnerships between OAE researchers, communities, advocacy groups, ministries of health, non-governmental organisations, the pharmaceutical industry and funding organizations. Although the exact pathophysiological mechanism underlying OAE remains unknown, there is increasing evidence that by controlling and eliminating onchocerciasis, OAE will also disappear. Therefore, OAE constitutes an additional argument for strengthening onchocerciasis elimination efforts. Given the high numbers of

A Systematic Review of Experimental Paradigms for Exploring Biased Interpretation of Ambiguous Information with Emotional and Neutral Associations

PubMed Central

Schoth, Daniel E.; Liossi, Christina

2017-01-01

Interpretation biases have been extensively explored in a range of populations, including patients with anxiety and depressive disorders where they have been argued to influence the onset and maintenance of such conditions. Other populations in which interpretation biases have been explored include patients with chronic pain, anorexia nervosa, and alcohol dependency among others, although this literature is more limited. In this research, stimuli with threatening/emotional and neutral meanings are presented, with participant responses indicative of ambiguity resolution. A large number of paradigms have been designed and implemented in the exploration of interpretation biases, some varying in minor features only. This article provides a review of experimental paradigms available for exploring interpretation biases, with the aim to stimulate and inform the design of future research exploring cognitive biases across a range of populations. A systematic search of the experimental literature was conducted in Medline, PsychINFO, Web of Science, CINAHL, and Cochrane Library databases. Search terms were information, stimuli, and ambiguous intersected with the terms interpretation and bias*. Forty-five paradigms were found, categorized into those using ambiguous words, ambiguous images, and ambiguous scenarios. The key features, strengths and limitations of the paradigms identified are discussed. PMID:28232813

A Systematic Review of Experimental Paradigms for Exploring Biased Interpretation of Ambiguous Information with Emotional and Neutral Associations.

PubMed

Schoth, Daniel E; Liossi, Christina

2017-01-01

Interpretation biases have been extensively explored in a range of populations, including patients with anxiety and depressive disorders where they have been argued to influence the onset and maintenance of such conditions. Other populations in which interpretation biases have been explored include patients with chronic pain, anorexia nervosa, and alcohol dependency among others, although this literature is more limited. In this research, stimuli with threatening/emotional and neutral meanings are presented, with participant responses indicative of ambiguity resolution. A large number of paradigms have been designed and implemented in the exploration of interpretation biases, some varying in minor features only. This article provides a review of experimental paradigms available for exploring interpretation biases, with the aim to stimulate and inform the design of future research exploring cognitive biases across a range of populations. A systematic search of the experimental literature was conducted in Medline, PsychINFO, Web of Science, CINAHL, and Cochrane Library databases. Search terms were information, stimuli , and ambiguous intersected with the terms interpretation and bias * . Forty-five paradigms were found, categorized into those using ambiguous words, ambiguous images, and ambiguous scenarios. The key features, strengths and limitations of the paradigms identified are discussed.

Vignettes of Ambiguity

ERIC Educational Resources Information Center

Gotz, Ignacio L.

2010-01-01

This article is an exploration of ambiguity as it appears in various guises in philosophical, social, political, and educational situations. Among these situations is the experience of exile. The exploration is conducted by means of literary anecdotes and real-life instances, hence the use of vignettes. The suggestion is made that ambiguity can be…

Lexical ambiguity resolution

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

Small, S.; Cottrell, G.; Tanenhaus, M.

1987-01-01

This book collects much of the best research currently available on the problem of lexical ambiguity resolution in the processing of human language. When taken out of context, sentences are usually ambiguous. When actually uttered in a dialogue or written in text, these same sentences often have unique interpretations. The inherent ambiguity of isolated sentences, becomes obvious in the attempt to write a computer program to understand them. Different views have emerged on the nature of context and the mechanisms by which it directs unambiguous understanding of words and sentences. These perspectives are represented and discussed. Eighteen original papers frommore » a valuable source book for cognitive scientists in AI, psycholinguistics, neuropsychology, or theoretical linguistics.« less

Charcoal evidence that rising atmospheric oxygen terminated Early Jurassic ocean anoxia

PubMed Central

Baker, Sarah J.; Hesselbo, Stephen P.; Lenton, Timothy M.; Duarte, Luís V.; Belcher, Claire M.

2017-01-01

The Toarcian Oceanic Anoxic Event (T-OAE) was characterized by a major disturbance to the global carbon(C)-cycle, and depleted oxygen in Earth's oceans resulting in marine mass extinction. Numerical models predict that increased organic carbon burial should drive a rise in atmospheric oxygen (pO2) leading to termination of an OAE after ∼1 Myr. Wildfire is highly responsive to changes in pO2 implying that fire-activity should vary across OAEs. Here we test this hypothesis by tracing variations in the abundance of fossil charcoal across the T-OAE. We report a sustained ∼800 kyr enhancement of fire-activity beginning ∼1 Myr after the onset of the T-OAE and peaking during its termination. This major enhancement of fire occurred across the timescale of predicted pO2 variations, and we argue this was primarily driven by increased pO2. Our study provides the first fossil-based evidence suggesting that fire-feedbacks to rising pO2 may have aided in terminating the T-OAE. PMID:28497785

Charcoal evidence that rising atmospheric oxygen terminated Early Jurassic ocean anoxia.

PubMed

Baker, Sarah J; Hesselbo, Stephen P; Lenton, Timothy M; Duarte, Luís V; Belcher, Claire M

2017-05-12

The Toarcian Oceanic Anoxic Event (T-OAE) was characterized by a major disturbance to the global carbon(C)-cycle, and depleted oxygen in Earth's oceans resulting in marine mass extinction. Numerical models predict that increased organic carbon burial should drive a rise in atmospheric oxygen (pO 2 ) leading to termination of an OAE after ∼1 Myr. Wildfire is highly responsive to changes in pO 2 implying that fire-activity should vary across OAEs. Here we test this hypothesis by tracing variations in the abundance of fossil charcoal across the T-OAE. We report a sustained ∼800 kyr enhancement of fire-activity beginning ∼1 Myr after the onset of the T-OAE and peaking during its termination. This major enhancement of fire occurred across the timescale of predicted pO 2 variations, and we argue this was primarily driven by increased pO 2 . Our study provides the first fossil-based evidence suggesting that fire-feedbacks to rising pO 2 may have aided in terminating the T-OAE.

Changes in calcareous nannoplankton calcification during the latest Cenomanian Oceanic Anoxic Event 2 and similarity with other Cretaceous Oceanic Anoxic Events

NASA Astrophysics Data System (ADS)

Faucher, Giulia; Erba, Elisabetta; Bottini, Cinzia

2016-04-01

The Cenomanian has been characterized by greenhouse climate conditions and profound environmental perturbations, including the latest Cenomanian Oceanic Anoxic Event 2 (OAE 2), an episode of widespread organic matter burial in oxygen-depleted oceans. OAE 2 is thought to be related to the emplacement of the Caribbean Plateau which probably introduced in the atmosphere a large amount of CO2 with consequent impact on biota, climate and ocean chemistry. The perturbation of the carbon cycle is reflected in the carbon isotopic record that evidences a positive shift at the OAE 2 onset and subsequent C-isotopic peaks. The aim of this study is the identification of possible changes in coccolith size/shape as a response to paleoenvironmental perturbations associated with OAE 2. Biometric analyses were performed on selected coccolith species (Biscutum constans, Discorhabdus rotatorius, Watznaueria barnesiae and Zeugrabdothus erectus) from five sections spanning the Cenomanian-Turonian boundary interval including OAE 2. The study provided evidence for size fluctuations and dwarfism of B. constans, Z. erectus and D. rotatorius during OAE 2, followed by a recovery at the end of the event. On the contrary, W. barnesiae displays constant sizes through the event. High-resolution investigations showed that B. constans follows the same size trends in all the analysed sections with i) a decrease in size at the OAE 2 onset where an increase in pCO2 is observed, ii) a partial increase in size back to pre-OAE 2 values around the first δ13C peak (peak A), where a decrease in pCO2 concentration is reconstructed iii) and a subsequent more expressed decrease in size reaching minimum values around the δ13C peak B where trace metal abundance has been identified. Small specimens are present till the end of OAE 2 and only after δ13C peak D a partial recovery in size is observed. Nannoplankton dwarfism is here interpreted as forced by rapidly increasing pCO2 during the formation of the

High-resolution C and O stable isotope geochemistry of the early Aptian OAE1a at Cau (Prebetic Zone, Spain): Preliminary results from sediment core.

NASA Astrophysics Data System (ADS)

Alejandro Ruiz-Ortiz, Pedro; Aguado, Roque; Castro, José Manuel; Gallego, David; de Gea, Ginés Alfonso; Jarvis, Ian; Molina, José Miguel; Nieto, Luis Miguel; Pancost, Richard; Quijano, María Luisa; Reolid, Matías; Rodriguez, Rafael; Skelton, Peter; Weisser, Helmut

2017-04-01

The occurrence of time intervals of enhanced deposition of organic matter (OM) during the Cretaceous, defined as Oceanic Anoxic Events (OAE), reflect abrupt changes in global carbon cycling. The Aptian OAE1a (120 Ma), represents an excellent example, recorded in all the main ocean basins, associated to massive burial of organic matter in marine sediments [1]. Much research has been done on the OAE1a from different sections in the world over the last decades, including the definition of the C-isotope stratigraphy of the event [2]. Notwithstanding, higher-resolution studies across the entire event will be crucial to shed light into the precise timing and rates of the different environmental and biotic changes that occurred. The Cau section is located in the easternmost part of the Prebetic Zone (Betic Cordillera), which represents the platform deposits of the Southern Iberian palaeomargin. The Lower Aptian of the Cau section is represented by a hemipelagic unit (Almadich Formation, ca. 200 m thick), deposited in a highly subsiding sector of a tilted block, located in the distal parts of the Prebetic Platform. Previous studies of the Lower Aptian of the Cau section have focused on the stratigraphy, bioevents, C-isotope stratigraphy, and organic and elemental geochemistry [3], [4], and in the reconstruction of pCO2 from organic geochemistry proxies [5]. All these studies reveal that the Cau section represents an excellent site to investigate the OAE 1a, based on its unusual high thickness and stratigraphic continuity, the quality and preservation of fossils and the geochemical signatures. Here we present the first results of a high-resolution carbonate C-isotope study based on the the analysis of three new research cores drilled at Cau in autumn 2015 [6]. These new data represent an important advance in the knowledge of the C-isotope record of the OAE 1a, presenting a more continuous record at a higher resolution than previous studies. This leads to the refining of the

Resolution Of Phase Ambiguities In QPSK

NASA Technical Reports Server (NTRS)

Nguyen, Tien M.

1992-01-01

Report discusses several techniques for resolution of phase ambiguities in detection and decoding of radio signals modulated by coherent quadrature phase-shift keying (QPSK) and offset QPSK (OQPSK). Eight ambiguities: four associated with phase of carrier signal in absence of ambiguity in direction of rotation of carrier phase, and another four associated with carrier phase in presence of phase-rotation ambiguity.

Neural Mechanisms Underlying Risk and Ambiguity Attitudes.

PubMed

Blankenstein, Neeltje E; Peper, Jiska S; Crone, Eveline A; van Duijvenvoorde, Anna C K

2017-11-01

Individual differences in attitudes to risk (a taste for risk, known probabilities) and ambiguity (a tolerance for uncertainty, unknown probabilities) differentially influence risky decision-making. However, it is not well understood whether risk and ambiguity are coded differently within individuals. Here, we tested whether individual differences in risk and ambiguity attitudes were reflected in distinct neural correlates during choice and outcome processing of risky and ambiguous gambles. To these ends, we developed a neuroimaging task in which participants ( n = 50) chose between a sure gain and a gamble, which was either risky or ambiguous, and presented decision outcomes (gains, no gains). From a separate task in which the amount, probability, and ambiguity level were varied, we estimated individuals' risk and ambiguity attitudes. Although there was pronounced neural overlap between risky and ambiguous gambling in a network typically related to decision-making under uncertainty, relatively more risk-seeking attitudes were associated with increased activation in valuation regions of the brain (medial and lateral OFC), whereas relatively more ambiguity-seeking attitudes were related to temporal cortex activation. In addition, although striatum activation was observed during reward processing irrespective of a prior risky or ambiguous gamble, reward processing after an ambiguous gamble resulted in enhanced dorsomedial PFC activation, possibly functioning as a general signal of uncertainty coding. These findings suggest that different neural mechanisms reflect individual differences in risk and ambiguity attitudes and that risk and ambiguity may impact overt risk-taking behavior in different ways.

Divided loyalties and ambiguous relationships.

PubMed

Toulmin, S

1986-01-01

The author argues that conflicts of obligation may, but need not, give rise to issues of divided loyalties. Given this, the question then becomes under what circumstances and conditions a simple internal conflict may escalate into the problem of divided loyalties or fiduciary ambiguities. After discussing conflicts of obligation, it is asserted that loyalties are divided only when the demands of the various relationships involved are irreconcilable. As this is an extreme, the major problematic issues fall, then, in between, on multiple loyalties and ambiguous loyalties. How and where multiple loyalties arise, and under what conditions they may become ambiguous loyalties lead to the recognition that moral problems are created by leaving in ambiguity things about the relationships involved that would be better sorted out. Finally the author looks at situations in which physicians are systematically exposed to irresoluble ambiguity.

Changes in coccolith sizes through Oceanic Anoxic Event 2: a proxy of ocean acidification?

NASA Astrophysics Data System (ADS)

Faucher, Giulia; Erba, Elisabetta

2013-04-01

The latest Cenomanian was a time of global paleoenvironmental changes: the normal pelagic sedimentation was abruptly interrupted by an episode of ocean-wide anoxia, named Oceanic Anoxic Event 2 (OAE2). The associated C isotopic positive excursion, documented in marine carbonate and organic matter as well as in terrestrial records, is caused by a major perturbation of the carbon budget, generally related to enhanced productivity and burial of organic matter. OAE2 was perhaps triggered by the extensive submarine volcanism during the formation of the Caribbean Plateau that acted as a natural source of CO2. The environmental perturbation recorded during OAE2 can be synthesized as follows: 1. The onset of OAE2 correlates with a major volcanic episode, causing global warming, a rise in CO2 and an increase in metals. 2. A weathering spike is followed by a cooling episode and CO2 drop in the interval of C isotopic peak A, under persisting volcanic emissions. 3. At C isotopic peak B, a major volcanic peak is associated with an increase in. 4. The end of OAE2 is marked by the decrease of C isotopic values after peak C with a return to normal metal concentrations, although temperatures remain relative warm. Here we present morphometric data of four nannofossil species in the OAE2 interval from different areas. The major result is a change to tiny-dwarf coccoliths, although of different amplitude, at the OAE2 onset. The inferred warmer conditions, higher fertility and excess CO2 suggest a potential role on nannoplankton calcification. Coccolith sizes return close to normal values around the C isotopic peak A, where minimum pCO2 and a cooling phase are reconstructed. A major reduction in size is recorded around C isotopic peak B, and coeval to an increase in volcanogenic CO2 based on metal spikes. The end of the C isotopic excursion doesn't correlate with a return to coccolith normal sizes, suggesting a protraction of anomalous conditions immediately after OAE2 termination. Our

Lexical ambiguity in sentence comprehension

PubMed Central

Mason, Robert A.; Just, Marcel Adam

2009-01-01

An event-related fMRI paradigm was used to investigate brain activity during the reading of sentences containing either a lexically ambiguous word or an unambiguous control word. Higher levels of activation occurred during the reading of sentences containing a lexical ambiguity. Furthermore, the activated cortical network differed, depending on: (1) whether the sentence contained a balanced (i.e., both meanings equally likely) or a biased (i.e., one meaning more likely than other meanings) ambiguous word; and, (2) the working memory capacity of the individual as assessed by reading span. The findings suggest that encountering a lexical ambiguity is dealt with by activating multiple meanings utilizing processes involving both hemispheres. When an early interpretation of a biased ambiguous word is later disambiguated to the subordinate meaning, the superior frontal cortex activates in response to the coherence break and the right inferior frontal gyrus and the insula activate, possibly to suppress the incorrect interpretation. Negative correlations between reading span scores and activation in the right hemisphere for both types of ambiguous words suggest that readers with lower spans are more likely to involve show right hemisphere involvement in the processing of the ambiguity. A positive correlation between reading span scores and insula activation appearing only for biased sentences disambiguated to the subordinate meaning indicates that individuals with higher spans were more likely to initially maintain both meanings and as a result had to suppress the unintended dominant meaning. PMID:17433891

Ambiguity effects of rhyme and meter.

PubMed

Wallot, Sebastian; Menninghaus, Winfried

2018-04-23

Previous research has shown that rhyme and meter-although enhancing prosodic processing ease and memorability-also tend to make semantic processing more demanding. Using a set of rhymed and metered proverbs, as well as nonrhymed and nonmetered versions of these proverbs, the present study reveals this hitherto unspecified difficulty of comprehension to be specifically driven by perceived ambiguity. Roman Jakobson was the 1st to propose this hypothesis, in 1960. He suggested that "ambiguity is an intrinsic, inalienable feature" of "parallelistic" diction of which the combination of rhyme and meter is a pronounced example. Our results show that ambiguity indeed explains a substantial portion of the rhyme- and meter-driven difficulty of comprehension. Longer word-reading times differentially reflected ratings for ambiguity and comprehension difficulty. However, the ambiguity effect is not "inalienable." Rather, many rhymed and metered sentences turned out to be low in ambiguity. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Valence and magnitude ambiguity in feedback processing.

PubMed

Gu, Ruolei; Feng, Xue; Broster, Lucas S; Yuan, Lu; Xu, Pengfei; Luo, Yue-Jia

2017-05-01

Outcome feedback which indicates behavioral consequences are crucial for reinforcement learning and environmental adaptation. Nevertheless, outcome information in daily life is often totally or partially ambiguous. Studying how people interpret this kind of information would provide important knowledge about the human evaluative system. This study concentrates on the neural processing of partially ambiguous feedback, that is, either its valence or magnitude is unknown to participants. To address this topic, we sequentially presented valence and magnitude information; electroencephalography (EEG) response to each kind of presentation was recorded and analyzed. The event-related potential components feedback-related negativity (FRN) and P3 were used as indices of neural activity. Consistent with previous literature, the FRN elicited by ambiguous valence was not significantly different from that elicited by negative valence. On the other hand, the FRN elicited by ambiguous magnitude was larger than both the large and small magnitude, indicating the motivation to seek unambiguous magnitude information. The P3 elicited by ambiguous valence and ambiguous magnitude was not significantly different from that elicited by negative valence and small magnitude, respectively, indicating the emotional significance of feedback ambiguity. Finally, the aforementioned effects also manifested in the stage of information integration. These findings indicate both similarities and discrepancies between the processing of valence ambiguity and that of magnitude ambiguity, which may help understand the mechanisms of ambiguous information processing.

Phonological ambiguity modulates resolution of semantic ambiguity during reading: An fMRI study of Hebrew.

PubMed

Bitan, Tali; Kaftory, Asaf; Meiri-Leib, Adi; Eviatar, Zohar; Peleg, Orna

2017-10-01

The current fMRI study examined the role of phonology in the extraction of meaning from print in each hemisphere by comparing homophonic and heterophonic homographs (ambiguous words in which both meanings have the same or different sounds respectively, e.g., bank or tear). The analysis distinguished between the first phase, in which participants read ambiguous words without context, and the second phase in which the context resolves the ambiguity. Native Hebrew readers were scanned during semantic relatedness judgments on pairs of words in which the first word was either a homophone or a heterophone and the second word was related to its dominant or subordinate meaning. In Phase 1 there was greater activation for heterophones in left inferior frontal gyrus (IFG), pars opercularis, and more activation for homophones in bilateral IFG pars orbitalis, suggesting that resolution of the conflict at the phonological level has abolished the semantic ambiguity for heterophones. Reduced activation for all ambiguous words in temporo-parietal regions suggests that although ambiguity enhances controlled lexical selection processes in frontal regions it reduces reliance on bottom-up mapping processes. After presentation of the context, a larger difference between the dominant and subordinate meaning was found for heterophones in all reading-related regions, suggesting a greater engagement for heterophones with the dominant meaning. Altogether these results are consistent with the prominent role of phonological processing in visual word recognition. Finally, despite differences in hemispheric asymmetry between homophones and heterophones, ambiguity resolution, even toward the subordinate meaning, is largely left lateralized. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

A Neural Signature Encoding Decisions under Perceptual Ambiguity

PubMed Central

Sun, Sai; Yu, Rongjun

2017-01-01

Abstract People often make perceptual decisions with ambiguous information, but it remains unclear whether the brain has a common neural substrate that encodes various forms of perceptual ambiguity. Here, we used three types of perceptually ambiguous stimuli as well as task instructions to examine the neural basis for both stimulus-driven and task-driven perceptual ambiguity. We identified a neural signature, the late positive potential (LPP), that encoded a general form of stimulus-driven perceptual ambiguity. In addition to stimulus-driven ambiguity, the LPP was also modulated by ambiguity in task instructions. To further specify the functional role of the LPP and elucidate the relationship between stimulus ambiguity, behavioral response, and the LPP, we employed regression models and found that the LPP was specifically associated with response latency and confidence rating, suggesting that the LPP encoded decisions under perceptual ambiguity. Finally, direct behavioral ratings of stimulus and task ambiguity confirmed our neurophysiological findings, which could not be attributed to differences in eye movements either. Together, our findings argue for a common neural signature that encodes decisions under perceptual ambiguity but is subject to the modulation of task ambiguity. Our results represent an essential first step toward a complete neural understanding of human perceptual decision making. PMID:29177189

A Neural Signature Encoding Decisions under Perceptual Ambiguity.

PubMed

Sun, Sai; Yu, Rongjun; Wang, Shuo

2017-01-01

People often make perceptual decisions with ambiguous information, but it remains unclear whether the brain has a common neural substrate that encodes various forms of perceptual ambiguity. Here, we used three types of perceptually ambiguous stimuli as well as task instructions to examine the neural basis for both stimulus-driven and task-driven perceptual ambiguity. We identified a neural signature, the late positive potential (LPP), that encoded a general form of stimulus-driven perceptual ambiguity. In addition to stimulus-driven ambiguity, the LPP was also modulated by ambiguity in task instructions. To further specify the functional role of the LPP and elucidate the relationship between stimulus ambiguity, behavioral response, and the LPP, we employed regression models and found that the LPP was specifically associated with response latency and confidence rating, suggesting that the LPP encoded decisions under perceptual ambiguity. Finally, direct behavioral ratings of stimulus and task ambiguity confirmed our neurophysiological findings, which could not be attributed to differences in eye movements either. Together, our findings argue for a common neural signature that encodes decisions under perceptual ambiguity but is subject to the modulation of task ambiguity. Our results represent an essential first step toward a complete neural understanding of human perceptual decision making.

Generative Learning: Adults Learning within Ambiguity

ERIC Educational Resources Information Center

Nicolaides, Aliki

2015-01-01

This study explored the extent to which ambiguity can serve as a catalyst for adult learning. The purpose of this study is to understand learning that is generated when encountering ambiguity agitated by the complexity of liquid modernity. "Ambiguity," in this study, describes an encounter with an appearance of reality that is at first…

Positive fEMG Patterns with Ambiguity in Paintings.

PubMed

Jakesch, Martina; Goller, Juergen; Leder, Helmut

2017-01-01

Whereas ambiguity in everyday life is often negatively evaluated, it is considered key in art appreciation. In a facial EMG study, we tested whether the positive role of visual ambiguity in paintings is reflected in a continuous affective evaluation on a subtle level. We presented ambiguous (disfluent) and non-ambiguous (fluent) versions of Magritte paintings and found that M. Zygomaticus major activation was higher and M. corrugator supercilii activation was lower for ambiguous than for non-ambiguous versions. Our findings reflect a positive continuous affective evaluation to visual ambiguity in paintings over the 5 s presentation time. We claim that this finding is indirect evidence for the hypothesis that visual stimuli classified as art, evoke a safe state for indulging into experiencing ambiguity, challenging the notion that processing fluency is generally related to positive affect.

Ambiguity Within Nursing Practice: An Evolutionary Concept Analysis.

PubMed

McMahon, Michelle A; Dluhy, Nancy M

2017-02-01

To analyze the concept of ambiguity in a nursing context. Ambiguity is inherent within nursing practice. As health care becomes increasingly complex, nurses must continue to successfully deal with greater amounts of clinical ambiguity. Although ambiguity is discussed in nursing, minimal concept refinement exists to capture the contextual intricacies from a nursing lens. Nurse perception of an ambiguous clinical event, in combination with nurse tolerance level for ambiguity, can impact nurse response. Yet, little is known about what constitutes ambiguity within nursing practice (AWNP). Rodgers evolutionary method was used to explore AWNP, with emphasis on nurse thinking during ambiguous clinical situations. Literature searches across multiple databases yielded 38 articles for analysis. Attributes of AWNP include (a) variations in cues/available information, (b) multiple interpretations, (c) novel/nonroutine presentations, and (d) unpredictable. Antecedents include (a) a context-specific, clinical situation with ambiguous features needing evaluation and (b) an individual to sense a knowledge gap or perceive ambiguity. Consequences include ranges of (a) emotional, (b) behavioral, and (c) cognitive clinician responses. Preliminary findings support AWNP as a distinct concept in which ambiguity perceived by the nurse likely affects judgment, decision making, and clinical interventions. AWNP is a clinically relevant concept requiring continued development.

Probability judgments under ambiguity and conflict

PubMed Central

Smithson, Michael

2015-01-01

Whether conflict and ambiguity are distinct kinds of uncertainty remains an open question, as does their joint impact on judgments of overall uncertainty. This paper reviews recent advances in our understanding of human judgment and decision making when both ambiguity and conflict are present, and presents two types of testable models of judgments under conflict and ambiguity. The first type concerns estimate-pooling to arrive at “best” probability estimates. The second type is models of subjective assessments of conflict and ambiguity. These models are developed for dealing with both described and experienced information. A framework for testing these models in the described-information setting is presented, including a reanalysis of a multi-nation data-set to test best-estimate models, and a study of participants' assessments of conflict, ambiguity, and overall uncertainty reported by Smithson (2013). A framework for research in the experienced-information setting is then developed, that differs substantially from extant paradigms in the literature. This framework yields new models of “best” estimates and perceived conflict. The paper concludes with specific suggestions for future research on judgment and decision making under conflict and ambiguity. PMID:26042081

Probability judgments under ambiguity and conflict.

PubMed

Smithson, Michael

2015-01-01

Whether conflict and ambiguity are distinct kinds of uncertainty remains an open question, as does their joint impact on judgments of overall uncertainty. This paper reviews recent advances in our understanding of human judgment and decision making when both ambiguity and conflict are present, and presents two types of testable models of judgments under conflict and ambiguity. The first type concerns estimate-pooling to arrive at "best" probability estimates. The second type is models of subjective assessments of conflict and ambiguity. These models are developed for dealing with both described and experienced information. A framework for testing these models in the described-information setting is presented, including a reanalysis of a multi-nation data-set to test best-estimate models, and a study of participants' assessments of conflict, ambiguity, and overall uncertainty reported by Smithson (2013). A framework for research in the experienced-information setting is then developed, that differs substantially from extant paradigms in the literature. This framework yields new models of "best" estimates and perceived conflict. The paper concludes with specific suggestions for future research on judgment and decision making under conflict and ambiguity.

Effect of ambiguities on SAR picture quality

NASA Technical Reports Server (NTRS)

Korwar, V. N.; Lipes, R. G.

1978-01-01

The degradation of picture quality is studied for a high-resolution, large-swath SAR mapping system subjected to speckle, additive white Gaussian noise, and range and azimuthal ambiguities occurring because of the non-finite antenna pattern produced by a square aperture antenna. The effect of the azimuth antenna pattern was accounted for by calculating the aximuth ambiguity function. Range ambiguities were accounted for by adding appropriate pixels at a range separation corresponding to one pulse repetition period, but attenuated by the antenna pattern. A method of estimating the range defocussing effect which arises from the azimuth matched filter being a function of range is shown. The resulting simulated picture was compared with one degraded by speckle and noise but no ambiguities. It is concluded that azimuth ambiguities don't cause any noticeable degradation but range ambiguities might.

Neural Correlates of Decision-Making Under Ambiguity and Conflict.

PubMed

Pushkarskaya, Helen; Smithson, Michael; Joseph, Jane E; Corbly, Christine; Levy, Ifat

2015-01-01

HIGHLIGHTS We use a simple gambles design in an fMRI study to compare two conditions: ambiguity and conflict.Participants were more conflict averse than ambiguity averse.Ambiguity aversion did not correlate with conflict aversion.Activation in the medial prefrontal cortex correlated with ambiguity level and ambiguity aversion.Activation in the ventral striatum correlated with conflict level and conflict aversion. Studies of decision making under uncertainty generally focus on imprecise information about outcome probabilities ("ambiguity"). It is not clear, however, whether conflicting information about outcome probabilities affects decision making in the same manner as ambiguity does. Here we combine functional magnetic resonance imaging (fMRI) and a simple gamble design to study this question. In this design the levels of ambiguity and conflict are parametrically varied, and ambiguity and conflict gambles are matched on expected value. Behaviorally, participants avoided conflict more than ambiguity, and attitudes toward ambiguity and conflict did not correlate across participants. Neurally, regional brain activation was differentially modulated by ambiguity level and aversion to ambiguity and by conflict level and aversion to conflict. Activation in the medial prefrontal cortex was correlated with the level of ambiguity and with ambiguity aversion, whereas activation in the ventral striatum was correlated with the level of conflict and with conflict aversion. These novel results indicate that decision makers process imprecise and conflicting information differently, a finding that has important implications for basic and clinical research.

Alcohol reduces aversion to ambiguity.

PubMed

Tyszka, Tadeusz; Macko, Anna; Stańczak, Maciej

2014-01-01

Several years ago, Cohen et al. (1958) demonstrated that under the influence of alcohol drivers became more risk prone, although their risk perception remained unchanged. Research shows that ambiguity aversion is to some extent positively correlated with risk aversion, though not very highly (Camerer and Weber, 1992). The question addressed by the present research is whether alcohol reduces ambiguity aversion. Our research was conducted in a natural setting (a restaurant bar), where customers with differing levels of alcohol intoxication were offered a choice between a risky and an ambiguous lottery. We found that alcohol reduced ambiguity aversion and that the effect occurred in men but not women. We interpret these findings in terms of the risk-as-value hypothesis, according to which, people in Western culture tend to value risk, and suggest that alcohol consumption triggers adherence to socially and culturally valued patterns of conduct different for men and women.

Effect of ambiguities on SAR picture quality

NASA Technical Reports Server (NTRS)

Korwar, V. N.; Lipes, R. G.

1978-01-01

The degradation of picture quality in a high-resolution, large-swath SAR mapping system caused by speckle, additive white Gaussian noise and range and azimuthal ambiguities occurring because of the nonfinite antenna pattern produced by a square aperture antenna was studied and simulated. The effect of the azimuth antenna pattern was accounted for by calculating the azimuth ambiguity function. Range ambiguities were accounted for by adding, to each pixel of interest, appropriate pixels at a range separation corresponding to one pulse repetition period, but attenuated by the antenna pattern. It is concluded that azimuth ambiguities do not cause any noticeable degradation (for large time bandwidth product systems, at least) but range ambiguities might.

Neural Correlates of Decision-Making Under Ambiguity and Conflict

PubMed Central

Pushkarskaya, Helen; Smithson, Michael; Joseph, Jane E.; Corbly, Christine; Levy, Ifat

2015-01-01

HIGHLIGHTS We use a simple gambles design in an fMRI study to compare two conditions: ambiguity and conflict.Participants were more conflict averse than ambiguity averse.Ambiguity aversion did not correlate with conflict aversion.Activation in the medial prefrontal cortex correlated with ambiguity level and ambiguity aversion.Activation in the ventral striatum correlated with conflict level and conflict aversion. Studies of decision making under uncertainty generally focus on imprecise information about outcome probabilities (“ambiguity”). It is not clear, however, whether conflicting information about outcome probabilities affects decision making in the same manner as ambiguity does. Here we combine functional magnetic resonance imaging (fMRI) and a simple gamble design to study this question. In this design the levels of ambiguity and conflict are parametrically varied, and ambiguity and conflict gambles are matched on expected value. Behaviorally, participants avoided conflict more than ambiguity, and attitudes toward ambiguity and conflict did not correlate across participants. Neurally, regional brain activation was differentially modulated by ambiguity level and aversion to ambiguity and by conflict level and aversion to conflict. Activation in the medial prefrontal cortex was correlated with the level of ambiguity and with ambiguity aversion, whereas activation in the ventral striatum was correlated with the level of conflict and with conflict aversion. These novel results indicate that decision makers process imprecise and conflicting information differently, a finding that has important implications for basic and clinical research. PMID:26640434

How Do Speakers Avoid Ambiguous Linguistic Expressions?

ERIC Educational Resources Information Center

Ferreira, V.S.; Slevc, L.R.; Rogers, E.S.

2005-01-01

Three experiments assessed how speakers avoid linguistically and nonlinguistically ambiguous expressions. Speakers described target objects (a flying mammal, bat) in contexts including foil objects that caused linguistic (a baseball bat) and nonlinguistic (a larger flying mammal) ambiguity. Speakers sometimes avoided linguistic-ambiguity, and they…

Sublexical ambiguity effect in reading Chinese disyllabic compounds.

PubMed

Huang, Hsu-Wen; Lee, Chia-Ying; Tsai, Jie-Li; Tzeng, Ovid J-L

2011-05-01

For Chinese compounds, neighbors can share either both orthographic forms and meanings, or orthographic forms only. In this study, central presentation and visual half-field (VF) presentation methods were used in conjunction with ERP measures to investigate how readers solve the sublexical semantic ambiguity of the first constituent character in reading a disyllabic compound. The sublexical ambiguity of the first character was manipulated while the orthographic neighborhood sizes of the first and second character (NS1, NS2) were controlled. Subjective rating of number of meanings corresponding to a character was used as an index of sublexical ambiguity. Results showed that low sublexical ambiguity words elicited a more negative N400 than high sublexical ambiguity words when words were centrally presented. Similar patterns were found when words were presented to the left VF. Interestingly, different patterns were observed for pseudowords. With left VF presentation, high sublexical ambiguity psudowords showed a more negative N400 than low sublexical ambiguity pseudowords. In contrast, with right VF presentation, low sublexical ambiguity pseudowords showed a more negative N400 than high sublexical ambiguity pseudowords. These findings indicate that a level of morphological representation between form and meaning needs to be established and refined in Chinese. In addition, hemispheric asymmetries in the use of word information in ambiguity resolution should be taken into account, even at sublexical level. 2011 Elsevier Inc. All rights reserved.

The Ethics of Strategic Ambiguity.

ERIC Educational Resources Information Center

Paul, Jim; Strbiak, Christy A.

1997-01-01

Examines the concept of strategic ambiguity in communication, and addresses the ethics of strategic ambiguity from an intrapersonal perspective that considers the congruity of communicators' espoused-ethics, ethics-in-use, and behavior, where ethical judgements are based on the congruity between espoused-ethics and actual behavior. Poses questions…

Sulfur cycling in plays an important role in the development of Ocean Anoxic Events

NASA Astrophysics Data System (ADS)

Gomes, M. L.; Raven, M. R.; Fike, D. A.; Gill, B. C.; Johnston, D. T.

2017-12-01

Ocean Anoxic Events (OAEs) are major carbon cycle perturbations marked by enhanced organic carbon deposition in the marine realm and carbon isotope excursions in organic and inorganic carbon. Although not as severe as the "big five" mass extinctions, OAEs had dire consequences for marine ecosystems and thus influenced Mesozoic evolutionary patterns. Sulfur cycle reconstructions provide insight into the biogeochemical processes that played a role in the development of OAEs because the sulfur cycle is linked with the carbon and oxygen cycles. We present sulfur and oxygen isotope records from carbonate-associated sulfate from the Toarcian OAE that documents a positive sulfate-oxygen isotope excursion of +6‰, which is similar to the magnitude of the positive sulfur isotope excursion documented at the same site and other globally distributed sites. This high-resolution record allows us to explore temporal variability in the onset of the isotopic excursions: the onset of the positive sulfate-oxygen isotope excursion occurs at the same stratigraphic interval as the onset of the positive carbon isotope excursion and both precede the onset of the positive sulfate-sulfur isotope excursion. Because oxygen is rapidly recycled during oxidative sulfur cycling, changes in oxidative sulfur cycling affect oxygen isotope values of sulfate without impacting sulfur isotope values. Thus, the early onset of the sulfate-oxygen isotope excursion implies a change in oxidative sulfur cycling, which is likely due to a shoaling of the zone of sulfate reduction. We explore the consequences of sulfate reduction zone shoaling for organic carbon preservation. Specifically, the sulfurization of organic matter, which makes organic matter less susceptible to degradation, occurs more rapidly when the top of the zone of sulfate reduction is near or above the sediment water interface. Therefore, we suggest that the shoaling of the sulfate reduction zone locally changed pathways of oxidative sulfur

[Diagnosis of ambiguous genitalia].

PubMed

de Sanctis, C; Einaudi, S; De Sanctis, L

1990-03-01

Diagnosis in patients with ambiguous genitalia is based on various investigations. Simple genital examination is not sufficient to attribute sex. Scarce androgenization in a male patient or marked androgenization in a female may both lead to the same stages of genital ambiguity according to Prader. It is important to get information about genital ambiguity in the family, drug consumption during gestation and signs of virilization in pregnant mothers. External genital findings must be integrated by visualization of urogenital sinus by X-rays, ultrasounds and endoscopy. Furthermore, hormonal evaluations on plasma and 24 hours urines allow diagnosis of some disorders of adrenal and gonadal steroidogenesis. To define genetic sex, chromosomal examination is required to integrate X chromatine investigation and fluorescent staining of Y chromosome. Evaluation of psychosexuality in patients who have already got gender identity is mandatory.

Isotope studies of carbonate rocks of La Luna Formation (Venezuela) to constrain the oceanic anoxic event 3 (OAE3)

NASA Astrophysics Data System (ADS)

Machado, M. C.; Chemale, F., Jr.; Kawashita, K.; Rey, O.; Moura, C. A. V.

2016-12-01

87Sr/86Sr ratios, δ13C, and δ18O determinations performed on 30 bulk carbonate rocks are presented to constrain the isotope characteristics regarding Oceanic Anoxic Event 3 in the La Luna Formation, Maracaibo Basin. The samples were collected along a 22 m profile in San Miguel region (Merida State, Venezuela). The exhibited 87Sr/86Sr ratios are between 0.707659, at the base, and 0.707733 at the top of studied section, corresponding estimated younger numerical ages than the inferred ages dated as Santonian (85.8-83.5 Ma) based on occurrence of Dicarinella asymetrica. The obtained 87Sr/86Sr ratios are certainly higher than expected for Santonian sea Sr and they are attributed to regular riverine strontium fluxes in the restricted (gulf-like) Maracaibo Basin. The values of δ18O data between -3.76‰ and -11.76‰ are distributed in two distinct clusters in a same way and coherent as for δ13C data which are in a range between -1.75‰ and -13.87‰. One of the clusters δ13C = -2.5 ± 1.0‰ and δ18O = -10.0 ± 1.5‰), illustrate the homogeneous marine deposition under tropical conditions, while the other, more variable, probably could reflect the cyclicity of temporally changes in Pacific versus Atlantic Ocean circulation with cooling water or cooling trend climate. These δ13C values around -2.5 ± 1.0‰ do not fit with the significant carbon isotope excursion as expected for the oceanic anoxic event (OAE) and support the work hypothesis that Coniacian-Santonian anoxic event (denominate as OAE3) is not a global one.

Clarity and ambiguity in psychoanalytic practice.

PubMed

Szajnberg, Nathan

2011-03-01

The author explores the presence and the essential tension between clarity and ambiguity as processes within our minds that become prominent in psychoanalysis. We learn from aesthetics and literary criticism that ambiguity can shade from taut disorganization to tolerating life's richness; clarity can range from a concrete fixity to a lucid grasp of one's state of mind. This article responds to Wallerstein's (1991) challenge to find common ground in psychoanalytic practice: We attempt this by avoiding metapsychological jargon and relying on more experience-near terms, such as clarity and ambiguity. The article also refers to Sandler's (1983) concept of implicit theory-that psychoanalysts use "preconscious, overlapping but not fully integrated models" (Sandler, 1988, p. 388)-in this case explicating how clarity and ambiguity are frequent but implicit phenomena in clinical work. Identifying these and the essential tension between them permits us to both improve training and identify our clinical efforts. The analyst's and analysand's tolerance of the tension between clarity and ambiguity facilitates increased structuralization and emotional robustness.

Lexical Ambiguities in the Vocabulary of Statistics

ERIC Educational Resources Information Center

Whitaker, Douglas

2016-01-01

Lexical ambiguities exist when two different meanings are ascribed to the same word. Such lexical ambiguities can be particularly problematic for learning material with technical words that have everyday meanings that are not the same as the technical meaning. This study reports on lexical ambiguities in six statistical words germane to statistics…

Recommendations for reducing ambiguity in written procedures.

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

Matzen, Laura E.

Previous studies in the nuclear weapons complex have shown that ambiguous work instructions (WIs) and operating procedures (OPs) can lead to human error, which is a major cause for concern. This report outlines some of the sources of ambiguity in written English and describes three recommendations for reducing ambiguity in WIs and OPs. The recommendations are based on commonly used research techniques in the fields of linguistics and cognitive psychology. The first recommendation is to gather empirical data that can be used to improve the recommended word lists that are provided to technical writers. The second recommendation is to havemore » a review in which new WIs and OPs and checked for ambiguities and clarity. The third recommendation is to use self-paced reading time studies to identify any remaining ambiguities before the new WIs and OPs are put into use. If these three steps are followed for new WIs and OPs, the likelihood of human errors related to ambiguity could be greatly reduced.« less

Community replacement instead of drowning: Evolution of proto-North Atlantic carbonate-platform production in the run-up to of the Early Aptian OAE1a

NASA Astrophysics Data System (ADS)

Huck, Stefan; Stein, Melody; Adatte, Thierry; Föllmi, Karl B.; Immenhauser, Adrian; Heimhofer, Ulrich

2014-05-01

In the proto-North Atlantic realm (Lusitanian Basin, Portugal), carbonate platform production witnessed a major biotic turnover during the Early Aptian. Here, Urgonian-type rudist-nerinid dominated limestones were replaced by an orbitolinid-rich, oyster and serpulid-bearing marly facies. Integrated biostratigraphic-chemostratigraphic studies (Burla et al., 2008; Huck et al., 2012) provided evidence that this change coincides with the Early Aptian carbonate platform drowning episode in the run-up of oceanic anoxic event (OAE) 1a (transition D. forbesi to D. deshayesi ammonite zones), which has been recorded, from many localities in the Tethyan Ocean (Godet, 2013). Unlike Helvetic and Arabian carbonate platforms, which are characterised by a punctuated mass occurrence of orbitolinids marking the onset of the Aptian (Rawil and Hawar members, respectively), orbitolinids are an abundant constituent of the proto-North Atlantic carbonate platform community from the Late Barremian onwards. Orbitolinid-rich packstones and marls showing mass-occurrences of orbitolinids indicate repeated short-term installation of specific environmental conditions (eutrophication and/or deepening). In order to critically assess the influence of regional palaeoenvironmental against global palaeoclimatic and palaeoceanographic changes on the Proto-North Atlantic carbonate platform evolution, several outcrop successions in the Lusitanian Basin covering the critical interval have been investigated in detail with regard to facies and petrographic characteristics and geochemical (C-/O-isotopes, P content, bulk-rock and clay mineralogy,) inventory. The aims of the present study are three-fold: (1) to characterise proto-North Atlantic Lower Aptian shallow-water carbonates with respect to diagenetic history, microfacies, and distribution of fossils useful for the analysis of palaeoenvironments (corals, rudists and orbitolinids); (2) to evaluate the influence of sea-level and humidity changes

Eliminating ambiguity in digital signals

NASA Technical Reports Server (NTRS)

Weber, W. J., III

1979-01-01

Multiamplitude minimum shift keying (mamsk) transmission system, method of differential encoding overcomes problem of ambiguity associated with advanced digital-transmission techniques with little or no penalty in transmission rate, error rate, or system complexity. Principle of method states, if signal points are properly encoded and decoded, bits are detected correctly, regardless of phase ambiguities.

Productive Ambiguity in the Learning of Mathematics

ERIC Educational Resources Information Center

Foster, Colin

2011-01-01

In this paper I take a positive view of ambiguity in the learning of mathematics. Following Grosholz (2007), I argue that it is not only the arts which exploit ambiguity for creative ends but science and mathematics too. By enabling the juxtaposition of multiple conflicting frames of reference, ambiguity allows novel connections to be made. I…

Ambiguous Loss Experienced by Transnational Mexican Immigrant Families.

PubMed

Solheim, Catherine; Zaid, Samantha; Ballard, Jaime

2016-06-01

In this study, an ambiguous loss framework as described by Boss (1999, Ambiguous loss: Learning to live with unresolved grief, First Harvard University Press, Cambridge, MA) was used to examine and understand the family experiences of Mexican immigrant agricultural workers in Minnesota. Transcripts from interviews with 17 workers in Minnesota and 17 family members in Mexico were analyzed using qualitative methodology to identify experiences of ambiguous loss in the participants' narratives. Key dimensions of ambiguous loss identified in the transcripts include: psychological family, feelings of chronic/recurring loss, finding support, and meaning making. In the category of psychological family, participants in both Mexico and the United States mourned the physical absence of their family members and experienced ambiguity regarding family responsibilities, but worked to maintain their psychological roles within the family. In the category of chronic/recurring loss, participants in both countries experienced chronic worry from not knowing if family members were safe, ambiguity regarding when the immigrant would return, and chronic stressors that compounded these feelings of loss. Participants in both countries coped with both real and ambiguous losses by accessing family support and by using ambiguous communication to minimize worry. Participants in Mexico also accessed work and community-based support. Participants in both countries made meaning of the ambiguous loss by identifying ways their lives were improved and goals were met as a result of the immigration for agricultural work in Minnesota. © 2015 Family Process Institute.

Common contextual influences in ambiguous and rivalrous figures

PubMed Central

Jennings, Ben J.; Kingdom, Frederick A. A.

2017-01-01

Images that resist binocular fusion undergo alternating periods of dominance and suppression, similarly to ambiguous figures whose percepts alternate between two interpretations. It has been well documented that the perceptual interpretations of both rivalrous and ambiguous figures are influenced by their spatio-temporal context. Here we consider whether an identical spatial context similarly influences the interpretation of a similar rivalrous and ambiguous figure. We developed a binocularly rivalrous stimulus whose perceptual experience mirrors that of a Necker cube. We employed a paradigm similar to that of Ouhnana and Kingdom (2016) to correlate the magnitude of influence of context between the rivalrous and ambiguous target. Our results showed that the magnitude of contextual influence is significantly correlated within observers between both binocularly rivalrous and ambiguous target figures. This points to a similar contextual-influence mechanism operating on a common mechanism underlying the perceptual instability in both ambiguous and rivalrous figures. PMID:28459854

Integer aperture ambiguity resolution based on difference test

NASA Astrophysics Data System (ADS)

Zhang, Jingyu; Wu, Meiping; Li, Tao; Zhang, Kaidong

2015-07-01

Carrier-phase integer ambiguity resolution (IAR) is the key to highly precise, fast positioning and attitude determination with Global Navigation Satellite System (GNSS). It can be seen as the process of estimating the unknown cycle ambiguities of the carrier-phase observations as integers. Once the ambiguities are fixed, carrier phase data will act as the very precise range data. Integer aperture (IA) ambiguity resolution is the combination of acceptance testing and integer ambiguity resolution, which can realize better quality control of IAR. Difference test (DT) is one of the most popular acceptance tests. This contribution will give a detailed analysis about the following properties of IA ambiguity resolution based on DT: 1. The sharpest and loose upper bounds of DT are derived from the perspective of geometry. These bounds are very simple and easy to be computed, which give the range for the critical values of DT.

Ambiguous data association and entangled attribute estimation

NASA Astrophysics Data System (ADS)

Trawick, David J.; Du Toit, Philip C.; Paffenroth, Randy C.; Norgard, Gregory J.

2012-05-01

This paper presents an approach to attribute estimation incorporating data association ambiguity. In modern tracking systems, time pressures often leave all but the most likely data association alternatives unexplored, possibly producing track inaccuracies. Numerica's Bayesian Network Tracking Database, a key part of its Tracker Adjunct Processor, captures and manages the data association ambiguity for further analysis and possible ambiguity reduction/resolution using subsequent data. Attributes are non-kinematic discrete sample space sensor data. They may be as distinctive as aircraft ID, or as broad as friend or foe. Attribute data may provide improvements to data association by a process known as Attribute Aided Tracking (AAT). Indeed, certain uniquely identifying attributes (e.g. aircraft ID), when continually reported, can be used to define data association (tracks are the collections of observations with the same ID). However, attribute data arriving infrequently, combined with erroneous choices from ambiguous data associations, can produce incorrect attribute and kinematic state estimation. Ambiguous data associations define the tracks that are entangled with each other. Attribute data observed on an entangled track then modify the attribute estimates on all tracks entangled with it. For example, if a red track and a blue track pass through a region of data association ambiguity, these tracks become entangled. Later red observations on one entangled track make the other track more blue, and reduce the data association ambiguity. Methods for this analysis have been derived and implemented for efficient forward filtering and forensic analysis.

Ambiguities and conventions in the perception of visual art.

PubMed

Mamassian, Pascal

2008-09-01

Vision perception is ambiguous and visual arts play with these ambiguities. While perceptual ambiguities are resolved with prior constraints, artistic ambiguities are resolved by conventions. Is there a relationship between priors and conventions? This review surveys recent work related to these ambiguities in composition, spatial scale, illumination and color, three-dimensional layout, shape, and movement. While most conventions seem to have their roots in perceptual constraints, those conventions that differ from priors may help us appreciate how visual arts differ from everyday perception.

Precise Point Positioning with Partial Ambiguity Fixing.

PubMed

Li, Pan; Zhang, Xiaohong

2015-06-10

Reliable and rapid ambiguity resolution (AR) is the key to fast precise point positioning (PPP). We propose a modified partial ambiguity resolution (PAR) method, in which an elevation and standard deviation criterion are first used to remove the low-precision ambiguity estimates for AR. Subsequently the success rate and ratio-test are simultaneously used in an iterative process to increase the possibility of finding a subset of decorrelated ambiguities which can be fixed with high confidence. One can apply the proposed PAR method to try to achieve an ambiguity-fixed solution when full ambiguity resolution (FAR) fails. We validate this method using data from 450 stations during DOY 021 to 027, 2012. Results demonstrate the proposed PAR method can significantly shorten the time to first fix (TTFF) and increase the fixing rate. Compared with FAR, the average TTFF for PAR is reduced by 14.9% for static PPP and 15.1% for kinematic PPP. Besides, using the PAR method, the average fixing rate can be increased from 83.5% to 98.2% for static PPP, from 80.1% to 95.2% for kinematic PPP respectively. Kinematic PPP accuracy with PAR can also be significantly improved, compared to that with FAR, due to a higher fixing rate.

Precise Point Positioning with Partial Ambiguity Fixing

PubMed Central

Li, Pan; Zhang, Xiaohong

2015-01-01

Reliable and rapid ambiguity resolution (AR) is the key to fast precise point positioning (PPP). We propose a modified partial ambiguity resolution (PAR) method, in which an elevation and standard deviation criterion are first used to remove the low-precision ambiguity estimates for AR. Subsequently the success rate and ratio-test are simultaneously used in an iterative process to increase the possibility of finding a subset of decorrelated ambiguities which can be fixed with high confidence. One can apply the proposed PAR method to try to achieve an ambiguity-fixed solution when full ambiguity resolution (FAR) fails. We validate this method using data from 450 stations during DOY 021 to 027, 2012. Results demonstrate the proposed PAR method can significantly shorten the time to first fix (TTFF) and increase the fixing rate. Compared with FAR, the average TTFF for PAR is reduced by 14.9% for static PPP and 15.1% for kinematic PPP. Besides, using the PAR method, the average fixing rate can be increased from 83.5% to 98.2% for static PPP, from 80.1% to 95.2% for kinematic PPP respectively. Kinematic PPP accuracy with PAR can also be significantly improved, compared to that with FAR, due to a higher fixing rate. PMID:26067196

Semantic Ambiguity Effects in L2 Word Recognition.

PubMed

Ishida, Tomomi

2018-06-01

The present study examined the ambiguity effects in second language (L2) word recognition. Previous studies on first language (L1) lexical processing have observed that ambiguous words are recognized faster and more accurately than unambiguous words on lexical decision tasks. In this research, L1 and L2 speakers of English were asked whether a letter string on a computer screen was an English word or not. An ambiguity advantage was found for both groups and greater ambiguity effects were found for the non-native speaker group when compared to the native speaker group. The findings imply that the larger ambiguity advantage for L2 processing is due to their slower response time in producing adequate feedback activation from the semantic level to the orthographic level.

Resolving Number Ambiguities during Language Comprehension

ERIC Educational Resources Information Center

Bader, Markus; Haussler, Jana

2009-01-01

This paper investigates how readers process number ambiguous noun phrases in subject position. A speeded-grammaticality judgment experiment and two self-paced reading experiments were conducted involving number ambiguous subjects in German verb-end clauses. Number preferences for individual nouns were estimated by means of two questionnaire…

SAR Ambiguity Study for the Cassini Radar

NASA Technical Reports Server (NTRS)

Hensley, Scott; Im, Eastwood; Johnson, William T. K.

1993-01-01

The Cassini Radar's synthetic aperture radar (SAR) ambiguity analysis is unique with respect to other spaceborne SAR ambiguity analyses owing to the non-orbiting spacecraft trajectory, asymmetric antenna pattern, and burst mode of data collection. By properly varying the pointing, burst mode timing, and radar parameters along the trajectory this study shows that the signal-to-ambiguity ratio of better than 15 dB can be achieved for all images obtained by the Cassini Radar.

Sedimentary Mercury Enrichments as a Marker for Submarine Large Igneous Province Volcanism? Evidence From the Mid-Cenomanian Event and Oceanic Anoxic Event 2 (Late Cretaceous)

NASA Astrophysics Data System (ADS)

Scaife, J. D.; Ruhl, M.; Dickson, A. J.; Mather, T. A.; Jenkyns, H. C.; Percival, L. M. E.; Hesselbo, S. P.; Cartwright, J.; Eldrett, J. S.; Bergman, S. C.; Minisini, D.

2017-12-01

Oceanic Anoxic Event 2 (OAE 2), during the Cenomanian-Turonian transition (˜94 Ma), was the largest perturbation of the global carbon cycle in the mid-Cretaceous and can be recognized by a positive carbon-isotope excursion in sedimentary strata. Although OAE 2 has been linked to large-scale volcanism, several large igneous provinces (LIPs) were active at this time (e.g., Caribbean, High Arctic, Madagascan, Ontong-Java) and little clear evidence links OAE 2 to a specific LIP. The Mid-Cenomanian Event (MCE, ˜96 Ma), identified by a small, 1‰ positive carbon-isotope excursion, is often referred to as a prelude to OAE 2. However, no underlying cause has yet been demonstrated and its relationship to OAE 2 is poorly constrained. Here we report sedimentary mercury (Hg) concentration data from four sites, three from the southern margin of the Western Interior Seaway and one from Demerara Rise, in the equatorial proto-North Atlantic Ocean. We find that, in both areas, increases in mercury concentrations and Hg/TOC ratios coincide with the MCE and the OAE 2. However, the increases found in these sites are of a lower magnitude than those found in records of many other Mesozoic events, possibly characteristic of a marine rather than atmospheric dispersal of mercury for both events. Combined, the new mercury data presented here are consistent with an initial magmatic pulse at the time of the MCE, with a second, greater pulse at the onset of OAE 2, possibly related to the emplacement of LIPs in the Pacific Ocean and/or the High Arctic.

Combined GPS/GLONASS Precise Point Positioning with Fixed GPS Ambiguities

PubMed Central

Pan, Lin; Cai, Changsheng; Santerre, Rock; Zhu, Jianjun

2014-01-01

Precise point positioning (PPP) technology is mostly implemented with an ambiguity-float solution. Its performance may be further improved by performing ambiguity-fixed resolution. Currently, the PPP integer ambiguity resolutions (IARs) are mainly based on GPS-only measurements. The integration of GPS and GLONASS can speed up the convergence and increase the accuracy of float ambiguity estimates, which contributes to enhancing the success rate and reliability of fixing ambiguities. This paper presents an approach of combined GPS/GLONASS PPP with fixed GPS ambiguities (GGPPP-FGA) in which GPS ambiguities are fixed into integers, while all GLONASS ambiguities are kept as float values. An improved minimum constellation method (MCM) is proposed to enhance the efficiency of GPS ambiguity fixing. Datasets from 20 globally distributed stations on two consecutive days are employed to investigate the performance of the GGPPP-FGA, including the positioning accuracy, convergence time and the time to first fix (TTFF). All datasets are processed for a time span of three hours in three scenarios, i.e., the GPS ambiguity-float solution, the GPS ambiguity-fixed resolution and the GGPPP-FGA resolution. The results indicate that the performance of the GPS ambiguity-fixed resolutions is significantly better than that of the GPS ambiguity-float solutions. In addition, the GGPPP-FGA improves the positioning accuracy by 38%, 25% and 44% and reduces the convergence time by 36%, 36% and 29% in the east, north and up coordinate components over the GPS-only ambiguity-fixed resolutions, respectively. Moreover, the TTFF is reduced by 27% after adding GLONASS observations. Wilcoxon rank sum tests and chi-square two-sample tests are made to examine the significance of the improvement on the positioning accuracy, convergence time and TTFF. PMID:25237901

Concept analysis: Role ambiguity in senior nursing students.

PubMed

Kalkman, Beth

2018-04-01

Role ambiguity is a lack of clarity or uncertainty related to one's position or role. Role ambiguity has been documented in the literature in relationship to athletics, industry, business, education, and nursing. However, a concept analysis has not been performed. Therefore, the process of concept analysis outlined by Walker and Avant is now used to look at the concept of role ambiguity and its relevance to senior nursing students' socialization and education into the profession of nursing. Attributes, antecedents, consequences, and empiric referents are discussed and theories commonly associated with role ambiguity are presented. At the end of the analysis, an operational definition is provided for use in exploring the concept of role ambiguity as it relates to senior nursing students' articulation of the role of the professional nurse. © 2017 Wiley Periodicals, Inc.

Ambiguous science and the visual representation of the real

NASA Astrophysics Data System (ADS)

Newbold, Curtis Robert

The emergence of visual media as prominent and even expected forms of communication in nearly all disciplines, including those scientific, has raised new questions about how the art and science of communication epistemologically affect the interpretation of scientific phenomena. In this dissertation I explore how the influence of aesthetics in visual representations of science inevitably creates ambiguous meanings. As a means to improve visual literacy in the sciences, I call awareness to the ubiquity of visual ambiguity and its importance and relevance in scientific discourse. To do this, I conduct a literature review that spans interdisciplinary research in communication, science, art, and rhetoric. Furthermore, I create a paradoxically ambiguous taxonomy, which functions to exploit the nuances of visual ambiguities and their role in scientific communication. I then extrapolate the taxonomy of visual ambiguity and from it develop an ambiguous, rhetorical heuristic, the Tetradic Model of Visual Ambiguity. The Tetradic Model is applied to a case example of a scientific image as a demonstration of how scientific communicators may increase their awareness of the epistemological effects of ambiguity in the visual representations of science. I conclude by demonstrating how scientific communicators may make productive use of visual ambiguity, even in communications of objective science, and I argue how doing so strengthens scientific communicators' visual literacy skills and their ability to communicate more ethically and effectively.

[Tolerance of ambiguity, art therapy and psychiatric illness].

PubMed

Grube, Michael

2002-11-01

Tolerance of ambiguity means the ability to tolerate contradictory and incalculable informations. There is the hypothesis that a high degree of tolerance of ambiguity correlates with creativity. It is unclear how various psychiatric illnesses and psychopathological conditions affect tolerance of ambiguity. Therefore we carried out a study concerning the tolerance of ambiguity: 154 persons were systematically investigated with a standardized questionnaire (31 schizophrenic in-patients, 41 neurotic in-patients, 49 members of the staff as control group, 33 artists as control group). In addition we examined the degree of depression in the neurotic group, the anancasm score and the well-being in general. In the schizophrenic group we assessed psychotic symptoms, the positive and negative symptoms, medication, anancasm and depression. Tolerance of ambiguity decreased in the following sequence: artists - members of the staff - neurotic in-patients - schizophrenic in-patients. It became evident that in the schizophrenic group negative symptoms negatively correlates with tolerance of ambiguity. The results seem to confirm the hypothesis that there is a positive correlation between tolerance of ambiguity and creativity. In addition, the higher degree of intolerance of ambiguity in schizophrenic patients may represent a protective mechanism. Intolerance of ambiguity possibly protects from too many contradictory informations. Furthermore the necessity is confirmed that creative therapy methods should be carefully chosen to avoid irritation on the one hand and not to neglect the required training of creative basic functions on the other hand. Although our results weaken the thesis that psychiatric illness is generally associated with an increase of creativity they don't exclude that highly creative performances in some individuals are possible who are especially talented in spite of or even because of their emotional suffering.

Audio-visual onset differences are used to determine syllable identity for ambiguous audio-visual stimulus pairs

PubMed Central

ten Oever, Sanne; Sack, Alexander T.; Wheat, Katherine L.; Bien, Nina; van Atteveldt, Nienke

2013-01-01

Content and temporal cues have been shown to interact during audio-visual (AV) speech identification. Typically, the most reliable unimodal cue is used more strongly to identify specific speech features; however, visual cues are only used if the AV stimuli are presented within a certain temporal window of integration (TWI). This suggests that temporal cues denote whether unimodal stimuli belong together, that is, whether they should be integrated. It is not known whether temporal cues also provide information about the identity of a syllable. Since spoken syllables have naturally varying AV onset asynchronies, we hypothesize that for suboptimal AV cues presented within the TWI, information about the natural AV onset differences can aid in speech identification. To test this, we presented low-intensity auditory syllables concurrently with visual speech signals, and varied the stimulus onset asynchronies (SOA) of the AV pair, while participants were instructed to identify the auditory syllables. We revealed that specific speech features (e.g., voicing) were identified by relying primarily on one modality (e.g., auditory). Additionally, we showed a wide window in which visual information influenced auditory perception, that seemed even wider for congruent stimulus pairs. Finally, we found a specific response pattern across the SOA range for syllables that were not reliably identified by the unimodal cues, which we explained as the result of the use of natural onset differences between AV speech signals. This indicates that temporal cues not only provide information about the temporal integration of AV stimuli, but additionally convey information about the identity of AV pairs. These results provide a detailed behavioral basis for further neuro-imaging and stimulation studies to unravel the neurofunctional mechanisms of the audio-visual-temporal interplay within speech perception. PMID:23805110

Audio-visual onset differences are used to determine syllable identity for ambiguous audio-visual stimulus pairs.

PubMed

Ten Oever, Sanne; Sack, Alexander T; Wheat, Katherine L; Bien, Nina; van Atteveldt, Nienke

2013-01-01

Content and temporal cues have been shown to interact during audio-visual (AV) speech identification. Typically, the most reliable unimodal cue is used more strongly to identify specific speech features; however, visual cues are only used if the AV stimuli are presented within a certain temporal window of integration (TWI). This suggests that temporal cues denote whether unimodal stimuli belong together, that is, whether they should be integrated. It is not known whether temporal cues also provide information about the identity of a syllable. Since spoken syllables have naturally varying AV onset asynchronies, we hypothesize that for suboptimal AV cues presented within the TWI, information about the natural AV onset differences can aid in speech identification. To test this, we presented low-intensity auditory syllables concurrently with visual speech signals, and varied the stimulus onset asynchronies (SOA) of the AV pair, while participants were instructed to identify the auditory syllables. We revealed that specific speech features (e.g., voicing) were identified by relying primarily on one modality (e.g., auditory). Additionally, we showed a wide window in which visual information influenced auditory perception, that seemed even wider for congruent stimulus pairs. Finally, we found a specific response pattern across the SOA range for syllables that were not reliably identified by the unimodal cues, which we explained as the result of the use of natural onset differences between AV speech signals. This indicates that temporal cues not only provide information about the temporal integration of AV stimuli, but additionally convey information about the identity of AV pairs. These results provide a detailed behavioral basis for further neuro-imaging and stimulation studies to unravel the neurofunctional mechanisms of the audio-visual-temporal interplay within speech perception.

Decision-Making under Ambiguity Is Modulated by Visual Framing, but Not by Motor vs. Non-Motor Context. Experiments and an Information-Theoretic Ambiguity Model

PubMed Central

Grau-Moya, Jordi; Ortega, Pedro A.; Braun, Daniel A.

2016-01-01

A number of recent studies have investigated differences in human choice behavior depending on task framing, especially comparing economic decision-making to choice behavior in equivalent sensorimotor tasks. Here we test whether decision-making under ambiguity exhibits effects of task framing in motor vs. non-motor context. In a first experiment, we designed an experience-based urn task with varying degrees of ambiguity and an equivalent motor task where subjects chose between hitting partially occluded targets. In a second experiment, we controlled for the different stimulus design in the two tasks by introducing an urn task with bar stimuli matching those in the motor task. We found ambiguity attitudes to be mainly influenced by stimulus design. In particular, we found that the same subjects tended to be ambiguity-preferring when choosing between ambiguous bar stimuli, but ambiguity-avoiding when choosing between ambiguous urn sample stimuli. In contrast, subjects’ choice pattern was not affected by changing from a target hitting task to a non-motor context when keeping the stimulus design unchanged. In both tasks subjects’ choice behavior was continuously modulated by the degree of ambiguity. We show that this modulation of behavior can be explained by an information-theoretic model of ambiguity that generalizes Bayes-optimal decision-making by combining Bayesian inference with robust decision-making under model uncertainty. Our results demonstrate the benefits of information-theoretic models of decision-making under varying degrees of ambiguity for a given context, but also demonstrate the sensitivity of ambiguity attitudes across contexts that theoretical models struggle to explain. PMID:27124723

Decision-Making under Ambiguity Is Modulated by Visual Framing, but Not by Motor vs. Non-Motor Context. Experiments and an Information-Theoretic Ambiguity Model.

PubMed

Grau-Moya, Jordi; Ortega, Pedro A; Braun, Daniel A

2016-01-01

A number of recent studies have investigated differences in human choice behavior depending on task framing, especially comparing economic decision-making to choice behavior in equivalent sensorimotor tasks. Here we test whether decision-making under ambiguity exhibits effects of task framing in motor vs. non-motor context. In a first experiment, we designed an experience-based urn task with varying degrees of ambiguity and an equivalent motor task where subjects chose between hitting partially occluded targets. In a second experiment, we controlled for the different stimulus design in the two tasks by introducing an urn task with bar stimuli matching those in the motor task. We found ambiguity attitudes to be mainly influenced by stimulus design. In particular, we found that the same subjects tended to be ambiguity-preferring when choosing between ambiguous bar stimuli, but ambiguity-avoiding when choosing between ambiguous urn sample stimuli. In contrast, subjects' choice pattern was not affected by changing from a target hitting task to a non-motor context when keeping the stimulus design unchanged. In both tasks subjects' choice behavior was continuously modulated by the degree of ambiguity. We show that this modulation of behavior can be explained by an information-theoretic model of ambiguity that generalizes Bayes-optimal decision-making by combining Bayesian inference with robust decision-making under model uncertainty. Our results demonstrate the benefits of information-theoretic models of decision-making under varying degrees of ambiguity for a given context, but also demonstrate the sensitivity of ambiguity attitudes across contexts that theoretical models struggle to explain.

A United Methodist approach to end-of-life decisions: intentional ambiguity or ambiguous intentions.

PubMed

Thobaben, James R

1997-12-01

The position of the United Methodist Church on end-of-life decisions is best described as intentional ambiguity or ambiguous intentions or both. The paper analyzes the official position of the denomination and then considers the actions of a U.M.C. bishop who served as a foreman for a trial of Dr. Jack Kevorkian. In an effort to find some common ground within an increasingly divided denomination, the work concludes with a consideration of the work of John Wesley and his approach to human death.

WURCS 2.0 Update To Encapsulate Ambiguous Carbohydrate Structures.

PubMed

Matsubara, Masaaki; Aoki-Kinoshita, Kiyoko F; Aoki, Nobuyuki P; Yamada, Issaku; Narimatsu, Hisashi

2017-04-24

Accurate representation of structural ambiguity is important for storing carbohydrate structures containing varying levels of ambiguity in the literature and databases. Although many representations for carbohydrates have been developed in the past, a generalized but discrete representation format did not exist. We had previously developed the Web3 Unique Representation of Carbohydrate Structures (WURCS) in an attempt to define a generalizable and unique linear representation for carbohydrate structures. However, it lacked sufficient rules to uniquely describe ambiguous structures. In this work, we updated WURCS to handle such ambiguous monosaccharide structures. In particular, to handle structural ambiguity around (potential) carbonyl groups incidental to the carbohydrate analysis, we defined a representation of backbone carbons containing atomic-level ambiguity. As a result, we show that WURCS 2.0 can represent a wider variety of carbohydrate structures containing ambiguous monosaccharides, such as those whose ring closure is undefined or whose anomeric information is only known. This new format provides a representation of carbohydrates that was not possible before, and it is currently being used by the International Glycan Structure Repository GlyTouCan.

Blunted Ambiguity Aversion During Cost-Benefit Decisions in Antisocial Individuals.

PubMed

Buckholtz, Joshua W; Karmarkar, Uma; Ye, Shengxuan; Brennan, Grace M; Baskin-Sommers, Arielle

2017-05-17

Antisocial behavior is often assumed to reflect aberrant risk processing. However, many of the most significant forms of antisocial behavior, including crime, reflect the outcomes of decisions made under conditions of ambiguity rather than risk. While risk and ambiguity are formally distinct and experimentally dissociable, little is known about ambiguity sensitivity in individuals who engage in chronic antisocial behavior. We used a financial decision-making task in a high-risk community-based sample to test for associations between sensitivity to ambiguity, antisocial behavior, and arrest history. Sensitivity to ambiguity was lower in individuals who met diagnostic criteria for Antisocial Personality Disorder. Lower ambiguity sensitivity was also associated with higher externalizing (but not psychopathy) scores, and with higher levels of aggression (but not rule-breaking). Finally, blunted sensitivity to ambiguity also predicted a greater frequency of arrests. Together, these data suggest that alterations in cost-benefit decision-making under conditions of ambiguity may promote antisocial behavior.

Orbital time scale and new C-isotope record for Cenomanian-Turonian boundary stratotype

NASA Astrophysics Data System (ADS)

Sageman, Bradley B.; Meyers, Stephen R.; Arthur, Michael A.

2006-02-01

Previous time scales for the Cenomanian-Turonian boundary (CTB) interval containing Oceanic Anoxic Event II (OAE II) vary by a factor of three. In this paper we present a new orbital time scale for the CTB stratotype established independently of radiometric, biostratigraphic, or geochemical data sets, update revisions of CTB biostratigraphic zonation, and provide a new detailed carbon isotopic record for the CTB study interval. The orbital time scale allows an independent assessment of basal biozone ages relative to the new CTB date of 93.55 Ma (GTS04). The δ13Corg data document the abrupt onset of OAE II, significant variability in δ13Corg values, and values enriched to almost -22‰. These new data underscore the difficulty in defining OAE II termination. Using the new isotope curve and time scale, estimates of OAE II duration can be determined and exported to other sites based on integration of well-established chemostratigraphic and biostratigraphic datums. The new data will allow more accurate calculations of biogeochemical and paleobiologic rates across the CTB.

Pricing risk and ambiguity: the effect of perspective taking.

PubMed

Trautmann, Stefan T; Schmidt, Ulrich

2012-01-01

In the valuation of uncertain prospects, a difference is often observed between selling and buying perspectives. This paper distinguishes between risk (known probabilities) and ambiguity (unknown probabilities) in decisions under uncertainty and shows that the valuation disparity increases under ambiguity compared to risk. It is found that both the comparative versus noncomparative evaluation of risky and ambiguous prospects and the uniqueness of the valuation perspective (either seller or buyer) moderate this increase in the disparity under ambiguity. The finding is consistent with recent theoretical accounts of pricing under uncertainty. We discuss implications for market behaviour and for the ambiguity paradigm as a research tool.

Ambiguity aversion and household portfolio choice puzzles: Empirical evidence*

PubMed Central

Dimmock, Stephen G.; Kouwenberg, Roy; Mitchell, Olivia S.; Peijnenburg, Kim

2017-01-01

We test the relation between ambiguity aversion and five household portfolio choice puzzles: nonparticipation in equities, low allocations to equity, home-bias, own-company stock ownership, and portfolio under-diversification. In a representative US household survey, we measure ambiguity preferences using custom-designed questions based on Ellsberg urns. As theory predicts, ambiguity aversion is negatively associated with stock market participation, the fraction of financial assets in stocks, and foreign stock ownership, but it is positively related to own-company stock ownership. Conditional on stock ownership, ambiguity aversion is related to portfolio under-diversification, and during the financial crisis, ambiguity-averse respondents were more likely to sell stocks. PMID:28458446

Ambiguity aversion and household portfolio choice puzzles: Empirical evidence.

PubMed

Dimmock, Stephen G; Kouwenberg, Roy; Mitchell, Olivia S; Peijnenburg, Kim

2016-03-01

We test the relation between ambiguity aversion and five household portfolio choice puzzles: nonparticipation in equities, low allocations to equity, home-bias, own-company stock ownership, and portfolio under-diversification. In a representative US household survey, we measure ambiguity preferences using custom-designed questions based on Ellsberg urns. As theory predicts, ambiguity aversion is negatively associated with stock market participation, the fraction of financial assets in stocks, and foreign stock ownership, but it is positively related to own-company stock ownership. Conditional on stock ownership, ambiguity aversion is related to portfolio under-diversification, and during the financial crisis, ambiguity-averse respondents were more likely to sell stocks.

Neuropsychology of Aesthetic Judgment of Ambiguous and Non-Ambiguous Artworks

PubMed Central

Boccia, Maddalena; Barbetti, Sonia; Piccardi, Laura; Guariglia, Cecilia; Giannini, Anna Maria

2017-01-01

Several affective and cognitive processes have been found to be pivotal in affecting aesthetic experience of artworks and both neuropsychological as well as psychiatric symptoms have been found to affect artistic production. However, there is a paucity of studies directly investigating effects of brain lesions on aesthetic judgment. Here, we assessed the effects of unilateral brain damage on aesthetic judgment of artworks showing part/whole ambiguity. We asked 19 unilaterally brain-damaged patients (10 left and 9 right brain damaged patients, respectively LBDP and RBDP) and 20 age- and education-matched healthy individuals (controls, C) to rate 10 Arcimboldo’s ambiguous portraits (AP), 10 realistic Renaissance portraits (RP), 10 still life paintings (SL), and 10 Arcimboldo’s modified portraits where only objects/parts are detectable (AO). They were also administered a Navon task, a facial recognition test, and evaluated on visuo-perceptual and visuo-constructional abilities. Patients included in the study did not show any deficits that could affect the capability to explore and enjoy artworks. SL and RP was not affected by brain damage regardless of its laterality. On the other hand, we found that RBDP liked AP more than the C participants. Furthermore, we found a positive correlation between aesthetic judgment of AP and visuo-perceptual skills even if the single case analyses failed to find a systematic association between neuropsychological deficits and aesthetic judgment of AP. On the whole, the present data suggest that a right hemisphere lesion may affect aesthetic judgment of ambiguous artworks, even in the absence of exploration or constructional deficits. PMID:28335460

Shallow processing of ambiguous pronouns: evidence for delay.

PubMed

Stewart, Andrew J; Holler, Judith; Kidd, Evan

2007-12-01

Two self-paced reading-time experiments examined how ambiguous pronouns are interpreted under conditions that encourage shallow processing. In Experiment 1 we show that sentences containing ambiguous pronouns are processed at the same speed as those containing unambiguous pronouns under shallow processing, but more slowly under deep processing. We outline three possible models to account for the shallow processing of ambiguous pronouns. Two involve an initial commitment followed by possible revision, and the other involves a delay in interpretation. In Experiment 2 we provide evidence that supports the delayed model of ambiguous pronoun resolution under shallow processing. We found no evidence to support a processing system that makes an initial commitment to an interpretation of the pronoun when it is encountered. We extend the account of pronoun resolution proposed by Rigalleau, Caplan, and Baudiffier (2004) to include the treatment of ambiguous pronouns under shallow processing.

Ambiguities in spaceborne synthetic aperture radar systems

NASA Technical Reports Server (NTRS)

Li, F. K.; Johnson, W. T. K.

1983-01-01

An examination of aspects of spaceborne SAR time delay and Doppler ambiguities has led to the formulation of an accurate method for the evaluation of the ratio of ambiguity intensities to that of the signal, which has been applied to the nominal SAR system on Seasat. After discussing the variation of this ratio as a function of orbital latitude and attitude control error, it is shown that the detailed range migration-azimuth phase history of an ambiguity is different from that of a signal, so that the images of ambiguities are dispersed. Seasat SAR dispersed images are presented, and their dispersions are eliminated through an adjustment of the processing parameters. A method is also presented which uses a set of multiple pulse repetition sequences to determine the Doppler centroid frequency absolute values for SARs with high carrier frequencies and poor attitude measurements.

Children do not exhibit ambiguity aversion despite intact familiarity bias.

PubMed

Li, Rosa; Brannon, Elizabeth M; Huettel, Scott A

2014-01-01

The phenomenon of ambiguity aversion, in which risky gambles with known probabilities are preferred over ambiguous gambles with unknown probabilities, has been thoroughly documented in adults but never measured in children. Here, we use two distinct tasks to investigate ambiguity preferences of children (8- to 9-year-olds) and a comparison group of adults (19- to 27-year-olds). Across three separate measures, we found evidence for significant ambiguity aversion in adults but not in children and for greater ambiguity aversion in adults compared to children. As ambiguity aversion in adults has been theorized to result from a preference to bet on the known and avoid the unfamiliar, we separately measured familiarity bias and found that children, like adults, are biased towards the familiar. Our findings indicate that ambiguity aversion emerges across the course of development between childhood and adolescence, while a familiarity bias is already present in childhood.

Children do not exhibit ambiguity aversion despite intact familiarity bias

PubMed Central

Li, Rosa; Brannon, Elizabeth M.; Huettel, Scott A.

2015-01-01

The phenomenon of ambiguity aversion, in which risky gambles with known probabilities are preferred over ambiguous gambles with unknown probabilities, has been thoroughly documented in adults but never measured in children. Here, we use two distinct tasks to investigate ambiguity preferences of children (8- to 9-year-olds) and a comparison group of adults (19- to 27-year-olds). Across three separate measures, we found evidence for significant ambiguity aversion in adults but not in children and for greater ambiguity aversion in adults compared to children. As ambiguity aversion in adults has been theorized to result from a preference to bet on the known and avoid the unfamiliar, we separately measured familiarity bias and found that children, like adults, are biased towards the familiar. Our findings indicate that ambiguity aversion emerges across the course of development between childhood and adolescence, while a familiarity bias is already present in childhood. PMID:25601848

PFC neurons reflect categorical decisions about ambiguous stimuli.

PubMed

Roy, Jefferson E; Buschman, Timothy J; Miller, Earl K

2014-06-01

We examined whether PFC neuron activity reflects categorical decisions in monkeys categorizing ambiguous stimuli. A morphing system was used to systematically vary stimulus shape and precisely define category boundaries. Ambiguous stimuli were centered on a category boundary, that is, they were a mix of 50% of two prototypes and therefore had no category information, so monkeys guessed at their category membership. We found that the monkeys' trial-by-trial decision about the category membership of an ambiguous image was reflected in PFC activity. Activity to the same ambiguous image differed significantly, depending on which category the monkey had assigned it to. This effect only occurred when that scheme was behaviorally relevant. These indicate that PFC activity reflects categorical decisions.

Commentary: ambiguity and uncertainty: neglected elements of medical education curricula?

PubMed

Luther, Vera P; Crandall, Sonia J

2011-07-01

Despite significant advances in scientific knowledge and technology, ambiguity and uncertainty are still intrinsic aspects of contemporary medicine. To practice confidently and competently, a physician must learn rational approaches to complex and ambiguous clinical scenarios and must possess a certain degree of tolerance of ambiguity. In this commentary, the authors discuss the role that ambiguity and uncertainty play in medicine and emphasize why openly addressing these topics in the formal medical education curriculum is critical. They discuss key points from original research by Wayne and colleagues and their implications for medical education. Finally, the authors offer recommendations for increasing medical student tolerance of ambiguity and uncertainty, including dedicating time to attend candidly to ambiguity and uncertainty as a formal part of every medical school curriculum.

Does ambiguity aversion influence the framing effect during decision making?

PubMed

Osmont, Anaïs; Cassotti, Mathieu; Agogué, Marine; Houdé, Olivier; Moutier, Sylvain

2015-04-01

Decision-makers present a systematic tendency to avoid ambiguous options for which the level of risk is unknown. This ambiguity aversion is one of the most striking decision-making biases. Given that human choices strongly depend on the options' presentation, the purpose of the present study was to examine whether ambiguity aversion influences the framing effect during decision making. We designed a new financial decision-making task involving the manipulation of both frame and uncertainty levels. Thirty-seven participants had to choose between a sure option and a gamble depicting either clear or ambiguous probabilities. The results revealed a clear preference for the sure option in the ambiguity condition regardless of frame. However, participants presented a framing effect in both the risk and ambiguity conditions. Indeed, the framing effect was bidirectional in the risk condition and unidirectional in the ambiguity condition given that it did not involve preference reversal but only a more extreme choice tendency.

Measuring Ambiguity in HLA Typing Methods

PubMed Central

Madbouly, Abeer; Freeman, John; Maiers, Martin

2012-01-01

In hematopoietic stem cell transplantation, donor selection is based primarily on matching donor and patient HLA genes. These genes are highly polymorphic and their typing can result in exact allele assignment at each gene (the resolution at which patients and donors are matched), but it can also result in a set of ambiguous assignments, depending on the typing methodology used. To facilitate rapid identification of matched donors, registries employ statistical algorithms to infer HLA alleles from ambiguous genotypes. Linkage disequilibrium information encapsulated in haplotype frequencies is used to facilitate prediction of the most likely haplotype assignment. An HLA typing with less ambiguity produces fewer high-probability haplotypes and a more reliable prediction. We estimated ambiguity for several HLA typing methods across four continental populations using an information theory-based measure, Shannon's entropy. We used allele and haplotype frequencies to calculate entropy for different sets of 1,000 subjects with simulated HLA typing. Using allele frequencies we calculated an average entropy in Caucasians of 1.65 for serology, 1.06 for allele family level, 0.49 for a 2002-era SSO kit, and 0.076 for single-pass SBT. When using haplotype frequencies in entropy calculations, we found average entropies of 0.72 for serology, 0.73 for allele family level, 0.05 for SSO, and 0.002 for single-pass SBT. Application of haplotype frequencies further reduces HLA typing ambiguity. We also estimated expected confirmatory typing mismatch rates for simulated subjects. In a hypothetical registry with all donors typed using the same method, the entropy values based on haplotype frequencies correspond to confirmatory typing mismatch rates of 1.31% for SSO versus only 0.08% for SBT. Intermediate-resolution single-pass SBT contains the least ambiguity of the methods we evaluated and therefore the most certainty in allele prediction. The presented measure objectively evaluates HLA

Not So Black and White: Memory for Ambiguous Group Members

PubMed Central

Pauker, Kristin; Weisbuch, Max; Ambady, Nalini; Sommers, Samuel R; Ivcevic, Zorana; Adams, Reginald B

2013-01-01

Exponential increases in multi-racial identities expected over the next century, creates a conundrum for perceivers accustomed to classifying people as “own” or “other” race. The current research examines how perceivers resolve this dilemma with regard to the “own-race bias.” We hypothesized that perceivers would not be motivated to include ambiguous-race individuals in the in-group and would therefore have some difficulty remembering them. Both racially-ambiguous and other-race faces were misremembered more often than own-race faces (Study 1), though memory for ambiguous faces was improved among perceivers motivated to include biracial individuals in the in-group (Study 2). Racial labels assigned to racially ambiguous faces determined memory for these faces, suggesting that uncertainty provides the motivational context for discounting ambiguous faces in memory (Study 3). Finally, an inclusion motivation fostered cognitive associations between racially-ambiguous faces and the in-group. Moreover, the extent to which perceivers associated racially-ambiguous faces with the in-group predicted memory for ambiguous faces and accounted for the impact of motivation on memory (Study 4). Thus, memory for biracial individuals seems to involve a flexible person construal process shaped by motivational factors. PMID:19309203

Enrichment Of Volcanogenic Trace Elements, Co, Cr, Cu, Ni, Mo And Zr In A Continuous Subsurface Eagle Ford Core In South Texas And Origin Of The Oceanic Anoxic Event II At The Cenomanian-Turonian (C/T) Boundary

NASA Astrophysics Data System (ADS)

Valencia, D.; Basu, A. R.; Loocke, M. P.

2017-12-01

The Eagle Ford Formation containing the Cenomanian-Turonian (C/T) boundary continues to be studied globally not only for its economic potential and analog for `frack-able' unconventional organic-rich formations, but it is of particular interest to researchers because it was deposited across the C/T boundary recording an Oceanic Anoxic Event (OAE2). OAEs are short lived episodes (< 1Ma) of widespread marine anoxia during which large amounts of organic carbon were buried on the ocean floor under oxygen-deficient bottom waters. The exact trigger for the increased deposition of organic matter into the sedimentary record remains enigmatic. Geochemical and geochronological analysis of a subsurface 300ft long continuous core of the Eagle Ford Formation of South Texas shows evidence for volcanism throughout. This is confirmed by multiple thin intermittent bentonite beds. The whole rock black shale (marl) shows elevated concentrations of volcanogenic trace elements (Co, Cr, Cu, Ni, Mo and Zn) throughout the core. By sampling bentonite bed zircons near the inferred C/T boundary, U-Pb age of 93.2 ±1.7 Ma for the Eagle Ford is established. Using this horizon, the onset of OAE2 is constrained and well-correlated with the positive δ13C excursion. For the trace element analysis, the core was sampled at 10ft intervals for ICP-MS. The analytical results show significantly increased volcanogenic trace metal input correlating with increased Total Organic Carbon and positive δ13C values at the C/T dated zircon horizon. OAE2, defined by the positive δ13C excursion, was found to span over an interval of 85ft. With a definitive constraint for OAE2 established, this well-defined interval was analyzed at a much higher resolution using ED-XRF. The core was then sampled at 6' intervals throughout the C/T boundary at OAE2. The high-resolution sampling of the core shows 80-99% increase in abundance of Co, Cr, Cu, Ni, Mo, Zn over the average Post Australian Archean Shale

Estimating ambiguity preferences and perceptions in multiple prior models: Evidence from the field

PubMed Central

Dimmock, Stephen G.; Kouwenberg, Roy; Mitchell, Olivia S.; Peijnenburg, Kim

2016-01-01

We develop a tractable method to estimate multiple prior models of decision-making under ambiguity. In a representative sample of the U.S. population, we measure ambiguity attitudes in the gain and loss domains. We find that ambiguity aversion is common for uncertain events of moderate to high likelihood involving gains, but ambiguity seeking prevails for low likelihoods and for losses. We show that choices made under ambiguity in the gain domain are best explained by the α-MaxMin model, with one parameter measuring ambiguity aversion (ambiguity preferences) and a second parameter quantifying the perceived degree of ambiguity (perceptions about ambiguity). The ambiguity aversion parameter α is constant and prior probability sets are asymmetric for low and high likelihood events. The data reject several other models, such as MaxMin and MaxMax, as well as symmetric probability intervals. Ambiguity aversion and the perceived degree of ambiguity are both higher for men and for the college-educated. Ambiguity aversion (but not perceived ambiguity) is also positively related to risk aversion. In the loss domain, we find evidence of reflection, implying that ambiguity aversion for gains tends to reverse into ambiguity seeking for losses. Our model’s estimates for preferences and perceptions about ambiguity can be used to analyze the economic and financial implications of such preferences. PMID:26924890

Estimating ambiguity preferences and perceptions in multiple prior models: Evidence from the field.

PubMed

Dimmock, Stephen G; Kouwenberg, Roy; Mitchell, Olivia S; Peijnenburg, Kim

2015-12-01

We develop a tractable method to estimate multiple prior models of decision-making under ambiguity. In a representative sample of the U.S. population, we measure ambiguity attitudes in the gain and loss domains. We find that ambiguity aversion is common for uncertain events of moderate to high likelihood involving gains, but ambiguity seeking prevails for low likelihoods and for losses. We show that choices made under ambiguity in the gain domain are best explained by the α-MaxMin model, with one parameter measuring ambiguity aversion (ambiguity preferences) and a second parameter quantifying the perceived degree of ambiguity (perceptions about ambiguity). The ambiguity aversion parameter α is constant and prior probability sets are asymmetric for low and high likelihood events. The data reject several other models, such as MaxMin and MaxMax, as well as symmetric probability intervals. Ambiguity aversion and the perceived degree of ambiguity are both higher for men and for the college-educated. Ambiguity aversion (but not perceived ambiguity) is also positively related to risk aversion. In the loss domain, we find evidence of reflection, implying that ambiguity aversion for gains tends to reverse into ambiguity seeking for losses. Our model's estimates for preferences and perceptions about ambiguity can be used to analyze the economic and financial implications of such preferences.

Comparing Tolerance of Ambiguity in Veterinary and Medical Students.

PubMed

Hancock, Jason; Hammond, Jennifer A; Roberts, Martin; Mattick, Karen

Current guidelines suggest that educators in both medical and veterinary professions should do more to ensure that students can tolerate ambiguity. Designing curricula to achieve this requires the ability to measure and understand differences in ambiguity tolerance among and within professional groups. Although scales have been developed to measure tolerance of ambiguity in both medical and veterinary professions, no comparative studies have been reported. We compared the tolerance of ambiguity of medical and veterinary students, hypothesizing that veterinary students would have higher tolerance of ambiguity, given the greater patient diversity and less well-established evidence base underpinning practice. We conducted a secondary analysis of questionnaire data from first- to fourth-year medical and veterinary students. Tolerance of ambiguity scores were calculated and compared using the TAMSAD scale (29 items validated for the medical student population), the TAVS scale (27 items validated for the veterinary student population), and a scale comprising the 22 items common to both scales. Using the TAMSAD and TAVS scales, medical students had a significantly higher mean tolerance of ambiguity score than veterinary students (56.1 vs. 54.1, p<.001 and 60.4 vs. 58.5, p=.002, respectively) but no difference was seen when only the 22 shared items were compared (56.1 vs. 57.2, p=.513). The results do not support our hypothesis and highlight that different findings can result when different tools are used. Medical students may have slightly higher tolerance of ambiguity than veterinary students, although this depends on the scale used.

Coding of level of ambiguity within neural systems mediating choice.

PubMed

Lopez-Paniagua, Dan; Seger, Carol A

2013-01-01

Data from previous neuroimaging studies exploring neural activity associated with uncertainty suggest varying levels of activation associated with changing degrees of uncertainty in neural regions that mediate choice behavior. The present study used a novel task that parametrically controlled the amount of information hidden from the subject; levels of uncertainty ranged from full ambiguity (no information about probability of winning) through multiple levels of partial ambiguity, to a condition of risk only (zero ambiguity with full knowledge of the probability of winning). A parametric analysis compared a linear model in which weighting increased as a function of level of ambiguity, and an inverted-U quadratic models in which partial ambiguity conditions were weighted most heavily. Overall we found that risk and all levels of ambiguity recruited a common "fronto-parietal-striatal" network including regions within the dorsolateral prefrontal cortex, intraparietal sulcus, and dorsal striatum. Activation was greatest across these regions and additional anterior and superior prefrontal regions for the quadratic function which most heavily weighs trials with partial ambiguity. These results suggest that the neural regions involved in decision processes do not merely track the absolute degree ambiguity or type of uncertainty (risk vs. ambiguity). Instead, recruitment of prefrontal regions may result from greater degree of difficulty in conditions of partial ambiguity: when information regarding reward probabilities important for decision making is hidden or not easily obtained the subject must engage in a search for tractable information. Additionally, this study identified regions of activity related to the valuation of potential gains associated with stimuli or options (including the orbitofrontal and medial prefrontal cortices and dorsal striatum) and related to winning (including orbitofrontal cortex and ventral striatum).

Coding of level of ambiguity within neural systems mediating choice

PubMed Central

Lopez-Paniagua, Dan; Seger, Carol A.

2013-01-01

Data from previous neuroimaging studies exploring neural activity associated with uncertainty suggest varying levels of activation associated with changing degrees of uncertainty in neural regions that mediate choice behavior. The present study used a novel task that parametrically controlled the amount of information hidden from the subject; levels of uncertainty ranged from full ambiguity (no information about probability of winning) through multiple levels of partial ambiguity, to a condition of risk only (zero ambiguity with full knowledge of the probability of winning). A parametric analysis compared a linear model in which weighting increased as a function of level of ambiguity, and an inverted-U quadratic models in which partial ambiguity conditions were weighted most heavily. Overall we found that risk and all levels of ambiguity recruited a common “fronto—parietal—striatal” network including regions within the dorsolateral prefrontal cortex, intraparietal sulcus, and dorsal striatum. Activation was greatest across these regions and additional anterior and superior prefrontal regions for the quadratic function which most heavily weighs trials with partial ambiguity. These results suggest that the neural regions involved in decision processes do not merely track the absolute degree ambiguity or type of uncertainty (risk vs. ambiguity). Instead, recruitment of prefrontal regions may result from greater degree of difficulty in conditions of partial ambiguity: when information regarding reward probabilities important for decision making is hidden or not easily obtained the subject must engage in a search for tractable information. Additionally, this study identified regions of activity related to the valuation of potential gains associated with stimuli or options (including the orbitofrontal and medial prefrontal cortices and dorsal striatum) and related to winning (including orbitofrontal cortex and ventral striatum). PMID:24367286

A Neural Mechanism for Time-Window Separation Resolves Ambiguity of Adaptive Coding

PubMed Central

Hildebrandt, K. Jannis; Ronacher, Bernhard; Hennig, R. Matthias; Benda, Jan

2015-01-01

The senses of animals are confronted with changing environments and different contexts. Neural adaptation is one important tool to adjust sensitivity to varying intensity ranges. For instance, in a quiet night outdoors, our hearing is more sensitive than when we are confronted with the plurality of sounds in a large city during the day. However, adaptation also removes available information on absolute sound levels and may thus cause ambiguity. Experimental data on the trade-off between benefits and loss through adaptation is scarce and very few mechanisms have been proposed to resolve it. We present an example where adaptation is beneficial for one task—namely, the reliable encoding of the pattern of an acoustic signal—but detrimental for another—the localization of the same acoustic stimulus. With a combination of neurophysiological data, modeling, and behavioral tests, we show that adaptation in the periphery of the auditory pathway of grasshoppers enables intensity-invariant coding of amplitude modulations, but at the same time, degrades information available for sound localization. We demonstrate how focusing the response of localization neurons to the onset of relevant signals separates processing of localization and pattern information temporally. In this way, the ambiguity of adaptive coding can be circumvented and both absolute and relative levels can be processed using the same set of peripheral neurons. PMID:25761097

The Communicative Function of Ambiguity in Language

ERIC Educational Resources Information Center

Piantadosi, Steven T.; Tily, Harry; Gibson, Edward

2012-01-01

We present a general information-theoretic argument that all efficient communication systems will be ambiguous, assuming that context is informative about meaning. We also argue that ambiguity allows for greater ease of processing by permitting efficient linguistic units to be re-used. We test predictions of this theory in English, German, and…

Intolerance for approach of ambiguity in social anxiety disorder.

PubMed

Kuckertz, Jennie M; Strege, Marlene V; Amir, Nader

2017-06-01

Previous research has utilised the approach-avoidance task (AAT) to measure approach and avoidance action tendencies in socially anxious individuals. "Neutral" social stimuli may be perceived as ambiguous and hence threatening to socially anxious individuals, however it is unclear whether this results in difficulty approaching ambiguous ("neutral") versus unambiguous threat (e.g. disgust) faces (i.e. intolerance of ambiguity). Thirty participants with social anxiety disorder (SADs) and 29 non-anxious controls completed an implicit AAT in which they were instructed to approach or avoid neutral and disgust faces (i.e. pull or push a joystick) based on colour of the picture border. Results indicated that SADs demonstrated greater difficulty approaching neutral relative to disgust faces. Moreover, intolerance for approach of ambiguity predicted social anxiety severity while controlling for the effects of trait anxiety and depression. Our results provide further support for the role of intolerance of ambiguity in SAD.

Dealing With Uncertainty: Testing Risk- and Ambiguity-Attitude Across Adolescence.

PubMed

Blankenstein, Neeltje E; Crone, Eveline A; van den Bos, Wouter; van Duijvenvoorde, Anna C K

2016-01-01

Attitudes to risk (known probabilities) and attitudes to ambiguity (unknown probabilities) are separate constructs that influence decision making, but their development across adolescence remains elusive. We administered a choice task to a wide adolescent age-range (N = 157, 10-25 years) to disentangle risk- and ambiguity-attitudes using a model-based approach. Additionally, this task was played in a social context, presenting choices from a high risk-taking peer. We observed age-related changes in ambiguity-attitude, but not risk-attitude. Also, ambiguity-aversion was negatively related to real-life risk taking. Finally, the social context influenced only risk-attitudes. These results highlight the importance of disentangling risk- and ambiguity-attitudes in adolescent risk taking.

How Does Ambiguity Affect Insurance Decisions

DTIC Science & Technology

1990-05-01

actuarially fair value is C=$100. As with the actuaries, the underwriters charge higher premiums when either p and/or L is ambiguous. Even for the case where...probabilities they reacted by increasing the premium (i.e., reducing C) particularly for the perfectly correlated case. Thus when p=.01, the actuarially fair ... value is C=100. When losses are perfectly correlated and the actuary faces an ambiguous probability, the median value is C=9. The probability would

Performance management and goal ambiguity: managerial implications in a single payer system.

PubMed

Calciolari, Stefano; Cantù, Elena; Fattore, Giovanni

2011-01-01

Goal ambiguity influences the effectiveness of performance management systems to drive organizations toward enhanced results. The literature analyzes the antecedents of goal ambiguity and shows the influence of goal ambiguity on the performance of U.S. federal agencies. However, no study has analyzed goal ambiguity in other countries or in health care systems. This study has three aims: to test the validity of a measurement instrument for goal ambiguity, to investigate its main antecedents, and to explore the relationship between goal ambiguity and organizational performance in a large, public, Beveridge-type health care system. A nationwide survey of general managers of the Italian national health system was performed. A factor analysis was used to validate the mono-dimensionality of an instrument that measured goal ambiguity. Structural equation modeling was used to test both the antecedents and the influence of goal ambiguity on organizational performance. Data from 135 health care organizations (53% response rate) were available for analysis. The results confirm the mono-dimensionality of the instrument, the existence of two environmental sources of ambiguity (political endorsement and governance commitment), and the negative relationship between goal ambiguity and organizational performance. Goal ambiguity matters because it may hamper organizational performance. Therefore, performance should be fostered by reducing goal ambiguity (e.g., goal-setting model, funding arrangements, and political support). Mutatis mutandis, our results may apply to public health care systems of other countries or other "public interest" sectors, such as social care and education.

Stimulus ambiguity elicits response conflict.

PubMed

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.

Persistence of Initial Misanalysis with No Referential Ambiguity

ERIC Educational Resources Information Center

Nakamura, Chie; Arai, Manabu

2016-01-01

Previous research reported that in processing structurally ambiguous sentences comprehenders often preserve an initial incorrect analysis even after adopting a correct analysis following structural disambiguation. One criticism is that the sentences tested in previous studies involved referential ambiguity and allowed comprehenders to make…

Some Structural Ambiguities.

ERIC Educational Resources Information Center

Stageberg, Norman C.

1958-01-01

The identification and study of 20 syntactical patterns responsible for much of the structural ambiguity found in literary composition can develop in students an audience awareness. When they realize that such constructions as "a dull boy's knife" and "the club will be open to members from Monday to Thursday" can be misinterpreted, they take more…

Spaceborne Hybrid Quad-Pol SAR Range Ambiguity Analysis and Simulations

NASA Astrophysics Data System (ADS)

Yang, Shilin; Li, Yang; Zhang, Jingjing; Hong, Wen

2014-11-01

The higher levels of range ambiguities in the cross-polarized measurement channels are the primary limitations for the matched quad-pol (e.g., HH, VV, VH, and HV) spaceborne synthetic aperture radar (SAR) systems. These ambiguities severely constrain the useful range of incident angles and the swath widths particularly at larger incidence. Adopting hybridpolarimetric architecture can remarkably reduce these ambiguities. In this paper, we analyse and develop the expression of range ambiguity to signal ratio (RASR) in the hybrid-polarimetric architecture. Simulations are made to testify this novel architecture’s advantage in the improvement of range ambiguities. The system operating parameters are derived from NASA’s DESDynl mission. In addition, we used the second order moments of polarimetric covariance matrices to depict target or the environment which are more precisely.

Spaceborne Hybrid Quad-Pol SAR Range Ambiguity Analysis and Simulations

NASA Astrophysics Data System (ADS)

Yang, Shilin; Li, Yang; Zhang, Jingjing; Hong, Wen

2014-11-01

The higher levels of range ambiguities in the cross- polarized measurement channels are the primary limitations for the matched quad-pol (e.g., HH, VV, VH, and HV) spaceborne synthetic aperture radar (SAR) systems. These ambiguities severely constrain the useful range of incident angles and the swath widths particularly at larger incidence. Adopting hybrid- polarimetric architecture can remarkably reduce these ambiguities. In this paper, we analyse and develop the expression of range ambiguity to signal ratio (RASR) in the hybrid-polarimetric architecture. Simulations are made to testify this novel architecture's advantage in the improvement of range ambiguities. The system operating parameters are derived from NASA's DESDynl mission. In addition, we used the second order moments of polarimetric covariance matrices to depict target or the environment which are more precisely.

Perceived ambiguity as a barrier to intentions to learn genome sequencing results.

PubMed

Taber, Jennifer M; Klein, William M P; Ferrer, Rebecca A; Han, Paul K J; Lewis, Katie L; Biesecker, Leslie G; Biesecker, Barbara B

2015-10-01

Many variants that could be returned from genome sequencing may be perceived as ambiguous-lacking reliability, credibility, or adequacy. Little is known about how perceived ambiguity influences thoughts about sequencing results. Participants (n = 494) in an NIH genome sequencing study completed a baseline survey before sequencing results were available. We examined how perceived ambiguity regarding sequencing results and individual differences in medical ambiguity aversion and tolerance for uncertainty were associated with cognitions and intentions concerning sequencing results. Perceiving sequencing results as more ambiguous was associated with less favorable cognitions about results and lower intentions to learn and share results. Among participants low in tolerance for uncertainty or optimism, greater perceived ambiguity was associated with lower intentions to learn results for non-medically actionable diseases; medical ambiguity aversion did not moderate any associations. Results are consistent with the phenomenon of "ambiguity aversion" and may influence whether people learn and communicate genomic information.

Reduction of Phase Ambiguity in an Offset-QPSK Receiver

NASA Technical Reports Server (NTRS)

Berner, Jeff; Kinman, Peter

2004-01-01

Proposed modifications of an offset-quadri-phase-shift keying (offset-QPSK) transmitter and receiver would reduce the amount of signal processing that must be done in the receiver to resolve the QPSK fourfold phase ambiguity. Resolution of the phase ambiguity is necessary in order to synchronize, with the received carrier signal, the signal generated by a local oscillator in a carrier-tracking loop in the receiver. Without resolution of the fourfold phase ambiguity, the loop could lock to any of four possible phase points, only one of which has the proper phase relationship with the carrier. The proposal applies, more specifically, to an offset-QPSK receiver that contains a carrier-tracking loop like that shown in Figure 1. This carrier-tracking loop does not resolve or reduce the phase ambiguity. A carrier-tracking loop of a different design optimized for the reception of offset QPSK could reduce the phase ambiguity from fourfold to twofold, but would be more complex. Alternatively, one could resolve the fourfold phase ambiguity by use of differential coding in the transmitter, at a cost of reduced power efficiency. The proposed modifications would make it possible to reduce the fourfold phase ambiguity to twofold, with no loss in power efficiency and only relatively simple additional signal-processing steps in the transmitter and receiver. The twofold phase ambiguity would then be resolved by use of a unique synchronization word, as is commonly done in binary phase-shift keying (BPSK). Although the mathematical and signal-processing principles underlying the modifications are too complex to explain in detail here, the modifications themselves would be relatively simple and are best described with the help of simple block diagrams (see Figure 2). In the transmitter, one would add a unit that would periodically invert bits going into the QPSK modulator; in the receiver, one would add a unit that would effect different but corresponding inversions of bits coming out

Cognitive Flexibility Supports Preschoolers' Detection of Communicative Ambiguity

ERIC Educational Resources Information Center

Gillis, Randall; Nilsen, Elizabeth S.

2014-01-01

To become successful communicators, children must be sensitive to the clarity/ambiguity of language. Significant gains in children's ability to detect communicative ambiguity occur during the early school-age years. However, little is known about the cognitive abilities that support this development. Relations between cognitive flexibility and…

On the ambiguity in relativistic tidal deformability

NASA Astrophysics Data System (ADS)

Gralla, Samuel E.

2018-04-01

The LIGO collaboration recently reported the first gravitational-wave constraints on the tidal deformability of neutron stars. I discuss an inherent ambiguity in the notion of relativistic tidal deformability that, while too small to affect the present measurement, may become important in the future. I propose a new way to understand the ambiguity and discuss future prospects for reliably linking observed gravitational waveforms to compact object microphysics.

On the possible onset of the Pioneer anomaly

NASA Astrophysics Data System (ADS)

Feldman, Michael R.; Anderson, John D.

2015-06-01

We explore the possibility that the observed onset of the Pioneer anomaly after Saturn encounter by Pioneer 11 is not necessarily due to mismodeling of solar radiation pressure but instead reflects a physically relevant characteristic of the anomaly itself. We employ the principles of a recently proposed cosmological model termed "the theory of inertial centers" along with an understanding of the fundamental assumptions taken by the Deep Space Network (DSN) to attempt to model this sudden onset. Due to an ambiguity that arises from the difference in the DSN definition of expected light-time with light-time according to the theory of inertial centers, we are forced to adopt a seemingly arbitrary convention to relate DSN-assumed clock-rates to physical clock-rates for this model. We offer a possible reason for adopting the convention employed in our analysis; however, we remain skeptical. Nevertheless, with this convention, one finds that this theory is able to replicate the previously reported Hubble-like behavior of the "clock acceleration" for the Pioneer anomaly as well as the sudden onset of the anomalous acceleration after Pioneer 11 Saturn encounter. While oscillatory behavior with a yearly period is also predicted for the anomalous clock accelerations of both Pioneer 10 and Pioneer 11, the predicted amplitude is an order of magnitude too small when compared with that reported for Pioneer 10.

An Investigation into Ambiguity Tolerance in Iranian Senior EFL Undergraduates

ERIC Educational Resources Information Center

Marzban, Amin; Barati, Hossein; Moinzadeh, Ahmad

2012-01-01

The present study aimed to explore how tolerant of ambiguity Iranian EFL learners at university level are and if gender plays a role in this regard. To this end, upon filling in the revised SLTAS scale of ambiguity tolerance 194 male and female Iranian teacher trainees were assigned to three ambiguity tolerance groups; namely, high, moderate and…

Ambiguity resolution in systems using Omega for position location

NASA Technical Reports Server (NTRS)

Frenkel, G.; Gan, D. G.

1974-01-01

The lane ambiguity problem prevents the utilization of the Omega system for many applications such as locating buoys and balloons. The method of multiple lines of position introduced herein uses signals from four or more Omega stations for ambiguity resolution. The coordinates of the candidate points are determined first through the use of the Newton iterative procedure. Subsequently, a likelihood function is generated for each point, and the ambiguity is resolved by selecting the most likely point. The method was tested through simulation.

Decision ambiguity is mediated by a late positive potential originating from cingulate cortex.

PubMed

Sun, Sai; Zhen, Shanshan; Fu, Zhongzheng; Wu, Daw-An; Shimojo, Shinsuke; Adolphs, Ralph; Yu, Rongjun; Wang, Shuo

2017-08-15

People often make decisions in the face of ambiguous information, but it remains unclear how ambiguity is represented in the brain. We used three types of ambiguous stimuli and combined EEG and fMRI to examine the neural representation of perceptual decisions under ambiguity. We identified a late positive potential, the LPP, which differentiated levels of ambiguity, and which was specifically associated with behavioral judgments about choices that were ambiguous, rather than passive perception of ambiguous stimuli. Mediation analyses together with two further control experiments confirmed that the LPP was generated only when decisions are made (not during mere perception of ambiguous stimuli), and only when those decisions involved choices on a dimension that is ambiguous. A further control experiment showed that a stronger LPP arose in the presence of ambiguous stimuli compared to when only unambiguous stimuli were present. Source modeling suggested that the LPP originated from multiple loci in cingulate cortex, a finding we further confirmed using fMRI and fMRI-guided ERP source prediction. Taken together, our findings argue for a role of an LPP originating from cingulate cortex in encoding decisions based on task-relevant perceptual ambiguity, a process that may in turn influence confidence judgment, response conflict, and error correction. Copyright © 2017 Elsevier Inc. All rights reserved.

Finding meaning in art: Preferred levels of ambiguity in art appreciation

PubMed Central

Jakesch, Martina; Leder, Helmut

2011-01-01

Uncertainty is typically not desirable in everyday experiences, but uncertainty in the form of ambiguity may be a defining feature of aesthetic experiences of modern art. In this study, we examined different hypotheses concerning the quantity and quality of information appreciated in art. Artworks were shown together with auditorily presented statements. We tested whether the amount of information, the amount of matching information, or the proportion of matching to nonmatching statements apparent in a picture (levels of ambiguity) affect liking and interestingness. Only the levels of ambiguity predicted differences in the two dependent variables. These findings reveal that ambiguity is an important determinant of aesthetic appreciation and that a certain level of ambiguity is appreciable. PMID:19565431

Ambiguity tolerance in organizations: definitional clarification and perspectives on future research.

PubMed

McLain, David L; Kefallonitis, Efstathios; Armani, Kimberly

2015-01-01

Ambiguity tolerance is an increasingly popular subject for study in a wide variety of fields. The definition of ambiguity tolerance has changed since its inception, and accompanying that change are changes in measurement and the research questions that interest researchers. There is a wealth of opportunity for research related to ambiguity tolerance and recent advances in neuroscience, measurement, trait research, perception, problem solving, and other fields highlight areas of interest and point to issues that need further attention. The future of ambiguity tolerance research is promising and it is expected that future studies will yield new insights into individual differences in reactions to the complex, unfamiliar, confusing, indeterminate, and incomplete stimuli that fall within the conceptual domain of ambiguity.

Children's Comprehension of Two Types of Syntactic Ambiguity

ERIC Educational Resources Information Center

Zimmer, Elly Jane

2017-01-01

This study asks whether children accept both interpretations of ambiguous sentences with contexts supporting each option. Twenty-six 3- to 5-year-old English-speaking children and a control group of 30 English-speaking adults participated in a truth value judgment task. As a step towards evaluating the complexity of syntactic ambiguity, the…

Development of a New Scale to Measure Ambiguity Tolerance in Veterinary Students.

PubMed

Hammond, Jennifer A; Hancock, Jason; Martin, Margaret S; Jamieson, Susan; Mellor, Dominic J

The ability to cope with ambiguity and feelings of uncertainty is an essential part of professional practice. Research with physicians has identified that intolerance of ambiguity or uncertainty is linked to stress, and some authors have hypothesized that there could be an association between intolerance of ambiguity and burnout. We describe the adaptation of the TAMSAD (Tolerance of Ambiguity in Medical Students and Doctors) scale for use with veterinary students. Exploratory factor analysis supports a uni-dimensional structure for the Ambiguity tolerance construct. Although internal reliability of the 29-item TAMSAD scale is reasonable (α=.50), an alternative 27-item scale (drawn from the original 41 items used to develop TAMSAD) shows higher internal reliability for veterinary students (α=.67). We conclude that there is good evidence to support the validity of this latter TAVS (Tolerance of Ambiguity in Veterinary Students) scale to study ambiguity tolerance in veterinary students.

Integer ambiguity resolution in precise point positioning: method comparison

NASA Astrophysics Data System (ADS)

Geng, Jianghui; Meng, Xiaolin; Dodson, Alan H.; Teferle, Felix N.

2010-09-01

Integer ambiguity resolution at a single receiver can be implemented by applying improved satellite products where the fractional-cycle biases (FCBs) have been separated from the integer ambiguities in a network solution. One method to achieve these products is to estimate the FCBs by averaging the fractional parts of the float ambiguity estimates, and the other is to estimate the integer-recovery clocks by fixing the undifferenced ambiguities to integers in advance. In this paper, we theoretically prove the equivalence of the ambiguity-fixed position estimates derived from these two methods by assuming that the FCBs are hardware-dependent and only they are assimilated into the clocks and ambiguities. To verify this equivalence, we implement both methods in the Position and Navigation Data Analyst software to process 1 year of GPS data from a global network of about 350 stations. The mean biases between all daily position estimates derived from these two methods are only 0.2, 0.1 and 0.0 mm, whereas the standard deviations of all position differences are only 1.3, 0.8 and 2.0 mm for the East, North and Up components, respectively. Moreover, the differences of the position repeatabilities are below 0.2 mm on average for all three components. The RMS of the position estimates minus those from the International GNSS Service weekly solutions for the former method differs by below 0.1 mm on average for each component from that for the latter method. Therefore, considering the recognized millimeter-level precision of current GPS-derived daily positions, these statistics empirically demonstrate the theoretical equivalence of the ambiguity-fixed position estimates derived from these two methods. In practice, we note that the former method is compatible with current official clock-generation methods, whereas the latter method is not, but can potentially lead to slightly better positioning quality.

Doppler centroid estimation ambiguity for synthetic aperture radars

NASA Technical Reports Server (NTRS)

Chang, C. Y.; Curlander, J. C.

1989-01-01

A technique for estimation of the Doppler centroid of an SAR in the presence of large uncertainty in antenna boresight pointing is described. Also investigated is the image degradation resulting from data processing that uses an ambiguous centroid. Two approaches for resolving ambiguities in Doppler centroid estimation (DCE) are presented: the range cross-correlation technique and the multiple-PRF (pulse repetition frequency) technique. Because other design factors control the PRF selection for SAR, a generalized algorithm is derived for PRFs not containing a common divisor. An example using the SIR-C parameters illustrates that this algorithm is capable of resolving the C-band DCE ambiguities for antenna pointing uncertainties of about 2-3 deg.

Perceived ambiguity as a barrier to intentions to learn genome sequencing results

PubMed Central

Taber, Jennifer M.; Klein, William M.P.; Ferrer, Rebecca A.; Han, Paul K. J.; Lewis, Katie L.; Biesecker, Leslie G.; Biesecker, Barbara B.

2015-01-01

Many variants that could be returned from genome sequencing may be perceived as ambiguous—lacking reliability, credibility, or adequacy. Little is known about how perceived ambiguity influences thoughts about sequencing results. Participants (n=494) in an NIH genome sequencing study completed a baseline survey before sequencing results were available. We examined how perceived ambiguity regarding sequencing results and individual differences in medical ambiguity aversion and tolerance for uncertainty were associated with cognitions and intentions concerning sequencing results. Perceiving sequencing results as more ambiguous was associated with less favorable cognitions about results and lower intentions to learn and share results. Among participants low in tolerance for uncertainty or optimism, greater perceived ambiguity was associated with lower intentions to learn results for non-medically actionable diseases; medical ambiguity aversion did not moderate any associations. Results are consistent with the phenomenon of “ambiguity aversion” and may influence whether people learn and communicate genomic information. PMID:26003053

A method of undifferenced ambiguity resolution for GPS+GLONASS precise point positioning

PubMed Central

Yi, Wenting; Song, Weiwei; Lou, Yidong; Shi, Chuang; Yao, Yibin

2016-01-01

Integer ambiguity resolution is critical for achieving positions of high precision and for shortening the convergence time of precise point positioning (PPP). However, GLONASS adopts the signal processing technology of frequency division multiple access and results in inter-frequency code biases (IFCBs), which are currently difficult to correct. This bias makes the methods proposed for GPS ambiguity fixing unsuitable for GLONASS. To realize undifferenced GLONASS ambiguity fixing, we propose an undifferenced ambiguity resolution method for GPS+GLONASS PPP, which considers the IFCBs estimation. The experimental result demonstrates that the success rate of GLONASS ambiguity fixing can reach 75% through the proposed method. Compared with the ambiguity float solutions, the positioning accuracies of ambiguity-fixed solutions of GLONASS-only PPP are increased by 12.2%, 20.9%, and 10.3%, and that of the GPS+GLONASS PPP by 13.0%, 35.2%, and 14.1% in the North, East and Up directions, respectively. PMID:27222361

A method of undifferenced ambiguity resolution for GPS+GLONASS precise point positioning.

PubMed

Yi, Wenting; Song, Weiwei; Lou, Yidong; Shi, Chuang; Yao, Yibin

2016-05-25

Integer ambiguity resolution is critical for achieving positions of high precision and for shortening the convergence time of precise point positioning (PPP). However, GLONASS adopts the signal processing technology of frequency division multiple access and results in inter-frequency code biases (IFCBs), which are currently difficult to correct. This bias makes the methods proposed for GPS ambiguity fixing unsuitable for GLONASS. To realize undifferenced GLONASS ambiguity fixing, we propose an undifferenced ambiguity resolution method for GPS+GLONASS PPP, which considers the IFCBs estimation. The experimental result demonstrates that the success rate of GLONASS ambiguity fixing can reach 75% through the proposed method. Compared with the ambiguity float solutions, the positioning accuracies of ambiguity-fixed solutions of GLONASS-only PPP are increased by 12.2%, 20.9%, and 10.3%, and that of the GPS+GLONASS PPP by 13.0%, 35.2%, and 14.1% in the North, East and Up directions, respectively.

Ambiguity tolerance in organizations: definitional clarification and perspectives on future research

PubMed Central

McLain, David L.; Kefallonitis, Efstathios; Armani, Kimberly

2015-01-01

Ambiguity tolerance is an increasingly popular subject for study in a wide variety of fields. The definition of ambiguity tolerance has changed since its inception, and accompanying that change are changes in measurement and the research questions that interest researchers. There is a wealth of opportunity for research related to ambiguity tolerance and recent advances in neuroscience, measurement, trait research, perception, problem solving, and other fields highlight areas of interest and point to issues that need further attention. The future of ambiguity tolerance research is promising and it is expected that future studies will yield new insights into individual differences in reactions to the complex, unfamiliar, confusing, indeterminate, and incomplete stimuli that fall within the conceptual domain of ambiguity. PMID:25972818

Apparent ambiguities in the post-Newtonian expansion for binary systems

NASA Astrophysics Data System (ADS)

Porto, Rafael A.; Rothstein, Ira Z.

2017-07-01

We discuss the source of the apparent ambiguities arising in the calculation of the dynamics of binary black holes within the post-Newtonian framework. Divergences appear in both the near and far zone calculations, and may be of either ultraviolet (UV) or infrared (IR) nature. The effective field theory (EFT) formalism elucidates the origin of the singularities which may introduce apparent ambiguities. In particular, the only (physical) "ambiguity parameters" that necessitate a matching calculation correspond to unknown finite size effects, which first appear at fifth post-Newtonian (5PN) order for nonspinning bodies. We demonstrate that the ambiguities linked to IR divergences in the near zone, that plague the recent derivations of the binding energy at 4PN order, both in the Arnowitt, Deser, and Misner (ADM) and "Fokker-action" approach, can be resolved by implementing the so-called zero-bin subtraction in the EFT framework. The procedure yields ambiguity-free results without the need of additional information beyond the PN expansion.

Method of resolving radio phase ambiguity in satellite orbit determination

NASA Technical Reports Server (NTRS)

Councelman, Charles C., III; Abbot, Richard I.

1989-01-01

For satellite orbit determination, the most accurate observable available today is microwave radio phase, which can be differenced between observing stations and between satellites to cancel both transmitter- and receiver-related errors. For maximum accuracy, the integer cycle ambiguities of the doubly differenced observations must be resolved. To perform this ambiguity resolution, a bootstrapping strategy is proposed. This strategy requires the tracking stations to have a wide ranging progression of spacings. By conventional 'integrated Doppler' processing of the observations from the most widely spaced stations, the orbits are determined well enough to permit resolution of the ambiguities for the most closely spaced stations. The resolution of these ambiguities reduces the uncertainty of the orbit determination enough to enable ambiguity resolution for more widely spaced stations, which further reduces the orbital uncertainty. In a test of this strategy with six tracking stations, both the formal and the true errors of determining Global Positioning System satellite orbits were reduced by a factor of 2.

Semantic Ambiguity Effects in L2 Word Recognition

ERIC Educational Resources Information Center

Ishida, Tomomi

2018-01-01

The present study examined the ambiguity effects in second language (L2) word recognition. Previous studies on first language (L1) lexical processing have observed that ambiguous words are recognized faster and more accurately than unambiguous words on lexical decision tasks. In this research, L1 and L2 speakers of English were asked whether a…

Optical Spatial integration methods for ambiguity function generation

NASA Technical Reports Server (NTRS)

Tamura, P. N.; Rebholz, J. J.; Daehlin, O. T.; Lee, T. C.

1981-01-01

A coherent optical spatial integration approach to ambiguity function generation is described. It uses one dimensional acousto-optic Bragg cells as input tranducers in conjunction with a space variant linear phase shifter, a passive optical element, to generate the two dimensional ambiguity function in one exposure. Results of a real time implementation of this system are shown.

Ambiguity of non-systematic chemical identifiers within and between small-molecule databases.

PubMed

Akhondi, Saber A; Muresan, Sorel; Williams, Antony J; Kors, Jan A

2015-01-01

A wide range of chemical compound databases are currently available for pharmaceutical research. To retrieve compound information, including structures, researchers can query these chemical databases using non-systematic identifiers. These are source-dependent identifiers (e.g., brand names, generic names), which are usually assigned to the compound at the point of registration. The correctness of non-systematic identifiers (i.e., whether an identifier matches the associated structure) can only be assessed manually, which is cumbersome, but it is possible to automatically check their ambiguity (i.e., whether an identifier matches more than one structure). In this study we have quantified the ambiguity of non-systematic identifiers within and between eight widely used chemical databases. We also studied the effect of chemical structure standardization on reducing the ambiguity of non-systematic identifiers. The ambiguity of non-systematic identifiers within databases varied from 0.1 to 15.2 % (median 2.5 %). Standardization reduced the ambiguity only to a small extent for most databases. A wide range of ambiguity existed for non-systematic identifiers that are shared between databases (17.7-60.2 %, median of 40.3 %). Removing stereochemistry information provided the largest reduction in ambiguity across databases (median reduction 13.7 percentage points). Ambiguity of non-systematic identifiers within chemical databases is generally low, but ambiguity of non-systematic identifiers that are shared between databases, is high. Chemical structure standardization reduces the ambiguity to a limited extent. Our findings can help to improve database integration, curation, and maintenance.

Adapting to an Uncertain World: Cognitive Capacity and Causal Reasoning with Ambiguous Observations

PubMed Central

Shou, Yiyun; Smithson, Michael

2015-01-01

Ambiguous causal evidence in which the covariance of the cause and effect is partially known is pervasive in real life situations. Little is known about how people reason about causal associations with ambiguous information and the underlying cognitive mechanisms. This paper presents three experiments exploring the cognitive mechanisms of causal reasoning with ambiguous observations. Results revealed that the influence of ambiguous observations manifested by missing information on causal reasoning depended on the availability of cognitive resources, suggesting that processing ambiguous information may involve deliberative cognitive processes. Experiment 1 demonstrated that subjects did not ignore the ambiguous observations in causal reasoning. They also had a general tendency to treat the ambiguous observations as negative evidence against the causal association. Experiment 2 and Experiment 3 included a causal learning task requiring a high cognitive demand in which paired stimuli were presented to subjects sequentially. Both experiments revealed that processing ambiguous or missing observations can depend on the availability of cognitive resources. Experiment 2 suggested that the contribution of working memory capacity to the comprehensiveness of evidence retention was reduced when there were ambiguous or missing observations. Experiment 3 demonstrated that an increase in cognitive demand due to a change in the task format reduced subjects’ tendency to treat ambiguous-missing observations as negative cues. PMID:26468653

European starlings unriddle the ambiguous-cue problem

PubMed Central

Vasconcelos, Marco; Monteiro, Tiago

2014-01-01

The ambiguous-cue problem is deceptively simple. It involves two concurrently trained simultaneous discriminations (known as PA and NA trials), but only three stimuli. Stimulus A is common to both discriminations, but serves as non-reinforced stimulus (S-) on PA trials and as reinforced stimulus (S+) on NA trials. Typically, animals’ accuracy is lower on PA trials—the ambiguous-cue effect. We conducted two experiments with European starlings (Sturnus vulgaris) using Urcuioli and Michalek’s (2007, Psychon B Rev 14, 658–662) experimental manipulations as a springboard to test the predictions of two of the most important theoretical accounts of the effect: the interfering cue hypothesis and value transfer theory. Both experiments included two groups of birds, one trained with a regular ambiguous-cue problem (Group Continuous) and another trained with partial reinforcement on PA trials (Group PA-Partial). The experiments differed only in the number of sessions (18 vs. 36) and daily trials (360 vs. 60). As previously observed, we found faster acquisition on NA trials than on PA trials in both experiments, but by the end of training PA performance was surprisingly high, such that no ambiguous-cue effect was present in Group Continuous of either experiment. The effect was still present in both PA-Partial groups, but to a smaller degree than expected. These findings are inconsistent with the literature, in particular with the results of Urcuioli and Michalek (2007) with pigeons, and question the aforementioned theoretical accounts as complete explanations of the ambiguous-cue effect. In our view, to achieve such high levels of accuracy on PA trials, starlings must have attended to configural (i.e., contextual) cues, thus differentiating stimulus A when presented on PA trials from stimulus A when presented on NA trials. A post hoc simulation of a reinforcement-based configural model supported our assertion. PMID:25206346

Attitudes toward risk and ambiguity in patients with autism spectrum disorder.

PubMed

Fujino, Junya; Tei, Shisei; Hashimoto, Ryu-Ichiro; Itahashi, Takashi; Ohta, Haruhisa; Kanai, Chieko; Okada, Rieko; Kubota, Manabu; Nakamura, Motoaki; Kato, Nobumasa; Takahashi, Hidehiko

2017-01-01

Although the ability to make optimal decisions under uncertainty is an integral part of everyday life, individuals with autism spectrum disorder (ASD) frequently report that they experience difficulties with this skill. In behavioral economics, researchers distinguish two types of uncertainty to understand decision-making in this setting: risk (known probabilities) and ambiguity (unknown probabilities). However, it remains unclear how individuals with ASD behave under risk and ambiguity, despite growing evidence of their altered decision-making under uncertainty. We therefore extended previous research by studying the attitudes of those with ASD toward risk and ambiguity in both positive and negative contexts (i.e., gain and loss). In gain contexts, no significant difference was observed between the groups in risk attitudes, but ambiguity aversion was attenuated in ASD. In loss contexts, ambiguity attitudes did not significantly differ between the groups, but the ASD participants were less risk-seeking compared with the controls. In addition, insensitivity to the context change under risk and ambiguity in ASD was both significantly associated with poor social skills. These results improve our understanding of altered decision-making under uncertainty by disentangling the attitudes toward risk and ambiguity in ASD individuals. Applying behavioral economic tools may provide insights into the mechanisms underlying behavioral disturbances in ASD.

Ambiguity's aftermath: how age differences in resolving lexical ambiguity affect subsequent comprehension.

PubMed

Lee, Chia-lin; Federmeier, Kara D

2012-04-01

When ambiguity resolution is difficult, younger adults recruit selection-related neural resources that older adults do not. To elucidate the nature of those resources and the consequences of their recruitment for subsequent comprehension, we embedded noun/verb homographs and matched unambiguous words in syntactically well-specified but semantically neutral sentences. Target words were followed by a prepositional phrase whose head noun was plausible for only one meaning of the homograph. Replicating past findings, younger but not older adults elicited sustained frontal negativity to homographs compared to unambiguous words. On the subsequent head nouns, younger adults showed plausibility effects in all conditions, attesting to successful meaning selection through suppression. In contrast, older adults showed smaller plausibility effects following ambiguous words and failed to show plausibility effects when the context picked out the homograph's non-dominant meaning (i.e., they did not suppress the contextually-irrelevant dominant meaning). Meaning suppression processes, reflected in the frontal negativity, thus become less available with age, with consequences for subsequent comprehension. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Antarctic Ozone Hole: New Approaches for Detection of the Onset of Stratospheric Ozone Recovery

NASA Astrophysics Data System (ADS)

de Laat, J.; van Weele, M.; van der A, R. J.

2016-12-01

An important aspect of human influences on climate concerns the Antarctic ozone hole, the strong thinning of the thickness of the ozone layer during springtime over Antarctica, first observed in the early 1980s. Antarctic stratospheric ozone is expected to fully recover in the second half of the 21st century because of policy measures to eliminate emissions of ozone depleting substances. Identification of the onset of this recovery would mark an important scientific and political milestone, but has remained difficult so far owing to natural climate variability and methodological ambiguities. In this presentation, we will first give a brief introduction to methods that have been used in the past to try to identify the onset of recovery, and discuss their shortcomings and ambiguities. Secondly, we introduce and discuss a several observations-based new approaches for ozone recovery detection in the Antarctic Ozone Hole that we have developed, explain why we believe these methods are more robust than standard methods, and outline how they circumvent crucial pitfalls of the previously used methods. Finally, we present our analyses, showing that these new approaches applied to various sets of remote sensing observations provide the best evidence to date that that ozone destruction within the Antarctic Ozone Hole has significantly decreased since approximately the year 2000, and which can be attributed to concurrently decreasing ozone depleting substances.

Roles of frontal and temporal regions in reinterpreting semantically ambiguous sentences

PubMed Central

Vitello, Sylvia; Warren, Jane E.; Devlin, Joseph T.; Rodd, Jennifer M.

2014-01-01

Semantic ambiguity resolution is an essential and frequent part of speech comprehension because many words map onto multiple meanings (e.g., “bark,” “bank”). Neuroimaging research highlights the importance of the left inferior frontal gyrus (LIFG) and the left posterior temporal cortex in this process but the roles they serve in ambiguity resolution are uncertain. One possibility is that both regions are engaged in the processes of semantic reinterpretation that follows incorrect interpretation of an ambiguous word. Here we used fMRI to investigate this hypothesis. 20 native British English monolinguals were scanned whilst listening to sentences that contained an ambiguous word. To induce semantic reinterpretation, the disambiguating information was presented after the ambiguous word and delayed until the end of the sentence (e.g., “the teacher explained that the BARK was going to be very damp”). These sentences were compared to well-matched unambiguous sentences. Supporting the reinterpretation hypothesis, these ambiguous sentences produced more activation in both the LIFG and the left posterior inferior temporal cortex. Importantly, all but one subject showed ambiguity-related peaks within both regions, demonstrating that the group-level results were driven by high inter-subject consistency. Further support came from the finding that activation in both regions was modulated by meaning dominance. Specifically, sentences containing biased ambiguous words, which have one more dominant meaning, produced greater activation than those with balanced ambiguous words, which have two equally frequent meanings. Because the context always supported the less frequent meaning, the biased words require reinterpretation more often than balanced words. This is the first evidence of dominance effects in the spoken modality and provides strong support that frontal and temporal regions support the updating of semantic representations during speech comprehension. PMID

The Learning Teacher: Role of Ambiguity in Education

ERIC Educational Resources Information Center

Suzawa, Gilbert S.

2013-01-01

Life is full of ambiguities, but as teachers we generally try to teach our students in a manner that sanitizes knowledge of all of its ambiguities. In doing so, we create an educational environment which forces students to learn in a rather meaningless fashion and this in turn leads to a lack of vitality and relevance within the academy. This need…

Attitude Toward Ambiguity: Empirically Robust Factors in Self-Report Personality Scales.

PubMed

Lauriola, Marco; Foschi, Renato; Mosca, Oriana; Weller, Joshua

2016-06-01

Two studies were conducted to examine the factor structure of attitude toward ambiguity, a broad personality construct that refers to personal reactions to perceived ambiguous stimuli in a variety of context and situations. Using samples from two countries, Study 1 mapped the hierarchical structure of 133 items from seven tolerance-intolerance of ambiguity scales (N = 360, Italy; N = 306, United States). Three major factors-Discomfort with Ambiguity, Moral Absolutism/Splitting, and Need for Complexity and Novelty-were recovered in each country with high replicability coefficients across samples. In Study 2 (N = 405, Italian community sample; N =366, English native speakers sample), we carried out a confirmatory analysis on selected factor markers. A bifactor model had an acceptable fit for each sample and reached the construct-level invariance for general and group factors. Convergent validity with related traits was assessed in both studies. We conclude that attitude toward ambiguity can be best represented a multidimensional construct involving affective (Discomfort with Ambiguity), cognitive (Moral Absolutism/Splitting), and epistemic (Need for Complexity and Novelty) components. © The Author(s) 2015.

Semantic ambiguity effects on traditional Chinese character naming: A corpus-based approach.

PubMed

Chang, Ya-Ning; Lee, Chia-Ying

2017-11-09

Words are considered semantically ambiguous if they have more than one meaning and can be used in multiple contexts. A number of recent studies have provided objective ambiguity measures by using a corpus-based approach and have demonstrated ambiguity advantages in both naming and lexical decision tasks. Although the predictive power of objective ambiguity measures has been examined in several alphabetic language systems, the effects in logographic languages remain unclear. Moreover, most ambiguity measures do not explicitly address how the various contexts associated with a given word relate to each other. To explore these issues, we computed the contextual diversity (Adelman, Brown, & Quesada, Psychological Science, 17; 814-823, 2006) and semantic ambiguity (Hoffman, Lambon Ralph, & Rogers, Behavior Research Methods, 45; 718-730, 2013) of traditional Chinese single-character words based on the Academia Sinica Balanced Corpus, where contextual diversity was used to evaluate the present semantic space. We then derived a novel ambiguity measure, namely semantic variability, by computing the distance properties of the distinct clusters grouped by the contexts that contained a given word. We demonstrated that semantic variability was superior to semantic diversity in accounting for the variance in naming response times, suggesting that considering the substructure of the various contexts associated with a given word can provide a relatively fine scale of ambiguity information for a word. All of the context and ambiguity measures for 2,418 Chinese single-character words are provided as supplementary materials.

Children's Understanding of Ambiguous Figures: Which Cognitive Developments Are Necessary to Experience Reversal

ERIC Educational Resources Information Center

Doherty, M.J.; Wimmer, M.C.

2005-01-01

In two experiments involving one hundred and thirty-eight 3- to 5-year-olds we examined the claim that a complex understanding of ambiguity is required to experience reversal of ambiguous stimuli [Gopnik, A., & Rosati, A. (2001). Duck or rabbit? Reversing ambiguous figures and understanding ambiguous representations. Developmental Science, 4,…

Role ambiguity, employee gender, and workplace friendship.

PubMed

Chen, Chien-Yu; Mao, Hsiao-Yen; Hsieh, An-Tien

2012-06-01

The importance of workplace friendship is recognized by researchers and practitioners, but its antecedents with respect to work roles are not well understood. Employees' gender might moderate a relationship between work roles and friendships. Data from a survey of 221 international tourist hotel employees showed that a key aspect of job support, role ambiguity, was negatively related to having workplace friendships. However, employees' gender did not moderate this relationship. Role clarity (the opposite of role ambiguity) may facilitate workplace friendships.

Ambiguous Loss in a Non-Western Context: Families of the Disappeared in Postconflict Nepal

ERIC Educational Resources Information Center

Robins, Simon

2010-01-01

Ambiguous loss has become a standard theory for understanding the impact of situations where the presence of a family member is subject to ambiguity. A number of studies of ambiguous loss have been made in a range of situations of ambiguity, but almost all have been firmly located within a Western cultural context. Here, ambiguous loss is explored…

De morseir syndrome presenting as ambiguous genitalia.

PubMed

Thukral, Anubhav; Chitra, S; Chakraborty, Partho P; Roy, Ajitesh; Goswami, Soumik; Bhattacharjee, Rana; Dutta, Deep; Maisnam, Indira; Ghosh, Sujoy; Mukherjee, Satinath; Chowdhury, Subhankar

2012-12-01

A 10-year-old boy presented with genital ambiguity, poor linear growth, and delayed milestones. The aim and to highlight that although rare but congenital, hypogonadotropic hypogonadism may rarely present as ambiguity. The patient was found to have bilateral cryptorchidism with proximal penile hypospadias, microphallus with a proportionate dwarfism with mildly delayed bone age, and karyotype 46XY. Euthyroid with normal steroid axis, growth hormone insufficient as suggested by auxology, low IGF1, and poor response to clonidine stimulation. MRI brain shows hypoplastic corpus callosum, hypoplastic anterior pituitary, and ectopic posterior pituitary bright spot. The patient underwent laparoscopic removal of right intrabdominal testis and orchidoplexy was performed on the left one. Testicular biopsy revealed no malignancy and growth hormone replacement was initiated. The patient awaits definitive repair of hypospadias. As a provisional diagnosis of combined growth hormone and gonadotropin deficiency, most probable diagnosis is septo-optic dysplasia or de moseir syndrome leading to genital ambiguity.

LIFG-based attentional control and the resolution of lexical ambiguities in sentence context

PubMed Central

Vuong, Loan C.; Martin, Randi C.

2010-01-01

The role of attentional control in lexical ambiguity resolution was examined in two patients with damage to the left inferior frontal gyrus (LIFG) and one control patient with non-LIFG damage. Experiment 1 confirmed that the LIFG patients had attentional control deficits compared to normal controls while the non-LIFG patient was relatively unimpaired. Experiment 2 showed that all three patients did as well as normal controls in using biasing sentence context to resolve lexical ambiguities involving balanced ambiguous words, but only the LIFG patients took an abnormally long time on lexical ambiguities that resolved toward a subordinate meaning of biased ambiguous words. Taken together, the results suggest that attentional control plays an important role in the resolution of certain lexical ambiguities – those that induce strong interference from context-inappropriate meanings (i.e., dominant meanings of biased ambiguous words). PMID:20971500

Kindergarten Children Can Be Taught to Detect Lexical Ambiguities

ERIC Educational Resources Information Center

Kamowski-Shakibai, Margaret T.; Cairns, Helen Smith

2016-01-01

This study investigates the development of metalinguistic skills, particularly ambiguity detection, and whether training accelerates this development for prereaders in kindergarten (5;5-6;6). It is the first to compare homophone detection with lexically ambiguous sentence detection in which the same homophones appear. The experimental group…

Neural responses to ambiguity involve domain-general and domain-specific emotion processing systems.

PubMed

Neta, Maital; Kelley, William M; Whalen, Paul J

2013-04-01

Extant research has examined the process of decision making under uncertainty, specifically in situations of ambiguity. However, much of this work has been conducted in the context of semantic and low-level visual processing. An open question is whether ambiguity in social signals (e.g., emotional facial expressions) is processed similarly or whether a unique set of processors come on-line to resolve ambiguity in a social context. Our work has examined ambiguity using surprised facial expressions, as they have predicted both positive and negative outcomes in the past. Specifically, whereas some people tended to interpret surprise as negatively valenced, others tended toward a more positive interpretation. Here, we examined neural responses to social ambiguity using faces (surprise) and nonface emotional scenes (International Affective Picture System). Moreover, we examined whether these effects are specific to ambiguity resolution (i.e., judgments about the ambiguity) or whether similar effects would be demonstrated for incidental judgments (e.g., nonvalence judgments about ambiguously valenced stimuli). We found that a distinct task control (i.e., cingulo-opercular) network was more active when resolving ambiguity. We also found that activity in the ventral amygdala was greater to faces and scenes that were rated explicitly along the dimension of valence, consistent with findings that the ventral amygdala tracks valence. Taken together, there is a complex neural architecture that supports decision making in the presence of ambiguity: (a) a core set of cortical structures engaged for explicit ambiguity processing across stimulus boundaries and (b) other dedicated circuits for biologically relevant learning situations involving faces.

Contextual Variation in Automatic Evaluative Bias to Racially-Ambiguous Faces

PubMed Central

Ito, Tiffany A.; Willadsen-Jensen, Eve C.; Kaye, Jesse T.; Park, Bernadette

2011-01-01

Three studies examined the implicit evaluative associations activated by racially-ambiguous Black-White faces. In the context of both Black and White faces, Study 1 revealed a graded pattern of bias against racially-ambiguous faces that was weaker than the bias to Black faces but stronger than that to White faces. Study 2 showed that significant bias was present when racially-ambiguous faces appeared in the context of only White faces, but not in the context of only Black faces. Study 3 demonstrated that context produces perceptual contrast effects on racial-prototypicality judgments. Racially-ambiguous faces were perceived as more prototypically Black in a White-only than mixed-race context, and less prototypically Black in a Black-only context. Conversely, they were seen as more prototypically White in a Black-only than mixed context, and less prototypically White in a White-only context. The studies suggest that both race-related featural properties within a face (i.e., racial ambiguity) and external contextual factors affect automatic evaluative associations. PMID:21691437

Performance analysis of multiple PRF technique for ambiguity resolution

NASA Technical Reports Server (NTRS)

Chang, C. Y.; Curlander, J. C.

1992-01-01

For short wavelength spaceborne synthetic aperture radar (SAR), ambiguity in Doppler centroid estimation occurs when the azimuth squint angle uncertainty is larger than the azimuth antenna beamwidth. Multiple pulse recurrence frequency (PRF) hopping is a technique developed to resolve the ambiguity by operating the radar in different PRF's in the pre-imaging sequence. Performance analysis results of the multiple PRF technique are presented, given the constraints of the attitude bound, the drift rate uncertainty, and the arbitrary numerical values of PRF's. The algorithm performance is derived in terms of the probability of correct ambiguity resolution. Examples, using the Shuttle Imaging Radar-C (SIR-C) and X-SAR parameters, demonstrate that the probability of correct ambiguity resolution obtained by the multiple PRF technique is greater than 95 percent and 80 percent for the SIR-C and X-SAR applications, respectively. The success rate is significantly higher than that achieved by the range cross correlation technique.

Tracking Early Jurassic marine (de)oxygenation

NASA Astrophysics Data System (ADS)

Them, T. R., II; Caruthers, A. H.; Gill, B. C.; Gröcke, D. R.; Marroquín, S. M.; Owens, J. D.

2017-12-01

It has been suggested that the carbon cycle was perturbed during the Toarcian OAE (T-OAE) as observed in the carbon isotope record, and more recently other elemental cycles (e.g., Hg, Mo, Os, S). The most widely accepted hypothesis focuses on the emplacement of the Karoo-Ferrar large igneous province, outgassing of greenhouse gases, and subsequent feedbacks in the Earth system, which caused severe environmental change and biological turnover. Feedbacks to elevated atmospheric pCO2 include enhanced weathering rates, dissociation of methane clathrates, increased terrestrial methanogenesis, and widespread marine anoxia. The sequence of events related to the development and duration of marine anoxia are not well constrained for this time interval due to a lack of open-ocean geochemical records. In order to reconstruct the timing of marine deoxygenation during the Early Jurassic T-OAE, we have utilized thallium isotopes, a novel geochemical proxy from multiple anoxic basins in North America and Germany. Three sites representing a basin transect from the Western Canada Sedimentary Basin, and one site from the South German Basin, were chosen to reconstruct the thallium isotopic composition (ɛ205Tl) of the ocean. The ɛ205Tl composition of sediments deposited under anoxic and euxinic water columns records the global seawater ɛ205Tl composition, a function of the amount of manganese oxides that are precipitated. Increased geographic extent of marine anoxia will cause a decrease in manganese oxide precipitation and perturb the thallium system. Importantly, the inputs of thallium are nearly identical, thus changes in these fluxes cannot drive the observed perturbation. Our new Early Jurassic ɛ205Tl records suggest that the onset of marine deoxygenation occurred concurrently with Karoo-Ferrar magmatism in the late Pliensbachian and continued until after the T-OAE. These new data support a Karoo-Ferrar trigger of the T-OAE. However, thallium isotopes also suggest that

Event ambiguity fuels the effective spread of rumors

NASA Astrophysics Data System (ADS)

Xu, Jiuping; Zhang, Yi

2015-08-01

In this paper, a new rumor spreading model which quantifies a specific rumor spreading feature is proposed. The specific feature focused on is the important role the event ambiguity plays in the rumor spreading process. To study the impact of this event ambiguity on the spread of rumors, the probability p(t) that an individual becomes a rumor spreader from an initially unaware person at time t is built. p(t) reflects the extent of event ambiguity, and a parameter c of p(t) is used to measure the speed at which the event moves from ambiguity to confirmation. At the same time, a principle is given to decide on the correct value for parameter c A rumor spreading model is then developed with this function added as a parameter to the traditional model. Then, several rumor spreading model simulations are conducted with different values for c on both regular networks and ER random networks. The simulation results indicate that a rumor spreads faster and more broadly when c is smaller. This shows that if events are ambiguous over a longer time, rumor spreading appears to be more effective, and is influenced more significantly by parameter c in a random network than in a regular network. We then determine parameters of this model through data fitting of the missing Malaysian plane, and apply this model to an analysis of the missing Malaysian plane. The simulation results demonstrate that the most critical time for authorities to control rumor spreading is in the early stages of a critical event.

Auditory Scene Analysis: The Sweet Music of Ambiguity

PubMed Central

Pressnitzer, Daniel; Suied, Clara; Shamma, Shihab A.

2011-01-01

In this review paper aimed at the non-specialist, we explore the use that neuroscientists and musicians have made of perceptual illusions based on ambiguity. The pivotal issue is auditory scene analysis (ASA), or what enables us to make sense of complex acoustic mixtures in order to follow, for instance, a single melody in the midst of an orchestra. In general, ASA uncovers the most likely physical causes that account for the waveform collected at the ears. However, the acoustical problem is ill-posed and it must be solved from noisy sensory input. Recently, the neural mechanisms implicated in the transformation of ambiguous sensory information into coherent auditory scenes have been investigated using so-called bistability illusions (where an unchanging ambiguous stimulus evokes a succession of distinct percepts in the mind of the listener). After reviewing some of those studies, we turn to music, which arguably provides some of the most complex acoustic scenes that a human listener will ever encounter. Interestingly, musicians will not always aim at making each physical source intelligible, but rather express one or more melodic lines with a small or large number of instruments. By means of a few musical illustrations and by using a computational model inspired by neuro-physiological principles, we suggest that this relies on a detailed (if perhaps implicit) knowledge of the rules of ASA and of its inherent ambiguity. We then put forward the opinion that some degree perceptual ambiguity may participate in our appreciation of music. PMID:22174701

Preferences for 'New' Treatments Diminish in the Face of Ambiguity.

PubMed

Harrison, Mark; Marra, Carlo A; Bansback, Nick

2017-06-01

New products usually offer advantages over existing products, but in health care, most new drugs are 'me-too', comparable in effectiveness and side effects to existing drugs, but with a more ambiguous evidence base around adverse effects. Despite this, new treatments drive increased health care spending, suggesting a preference for 'newness' in this setting. We explore (1) whether preferences for treatments labeled 'new' exist and (2) persist once the ambiguity in the evidence base reflecting newness is described. We use a Canadian general population sample (n = 2837) characterized by their innovativeness in adopting new products in normal markets. We found that innovators/early adopters (n = 173) had significant preferences for 'newer' treatments (B = 0.162, p = 0.038) irrespective of comparable benefits and side effects and all respondents had significant preferences for less ambiguity in benefit/side effect estimates. Notably, when 'newness' was combined with ambiguity, no significant preferences for new treatments were observed regardless of respondent innovativeness. We conclude that preferences for new products exist for some people in health care markets but disappear when the implication of ambiguity in the evidence base for new treatments is communicated. Physicians should avoid describing treatments as 'new' or be mindful to qualify the implications of 'new' treatments in terms of evidence ambiguity. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

PRF Ambiguity Detrmination for Radarsat ScanSAR System

NASA Technical Reports Server (NTRS)

Jin, Michael Y.

1998-01-01

PRF ambiguity is a potential problem for a spaceborne SAR operated at high frequencies. For a strip mode SAR, there were several approaches to solve this problem. This paper, however, addresses PRF ambiguity determination algorithms suitable for a burst mode SAR system such as the Radarsat ScanSAR. The candidate algorithms include the wavelength diversity algorithm, range look cross correlation algorithm, and multi-PRF algorithm.

Confronting Ambiguity in Science

ERIC Educational Resources Information Center

Emery, Katherine; Harlow, Danielle; Whitmer, Ali; Gaines, Steven

2015-01-01

People are regularly confronted with environmental and science-related issues presented to them in newspapers, on television, or even in their own doctor's office. Often the information they use to inform their decisions on matters of science may be ambiguous and contradictory. This article presents an activity that investigates how students deal…

Carbonate-platform response to the Toarcian Oceanic Anoxic Event in the southern hemisphere: Implications for climatic change and biotic platform demise

NASA Astrophysics Data System (ADS)

Han, Zhong; Hu, Xiumian; Kemp, David B.; Li, Juan

2018-05-01

The Toarcian Oceanic Anoxic Event (T-OAE, ∼183 Ma) was a profound short-term environmental perturbation associated with the large-scale release of 13C-depleted carbon into the global ocean-atmosphere system, which resulted in a significant negative carbon-isotope excursion (CIE). The general lack of characteristic T-OAE records outside of the northern hemisphere means that the precise environmental effects and significance of this event are uncertain. Many biotic carbonate platforms of the northern hemisphere western Tethys drowned or shifted to non-skeletal platforms during the early Toarcian. However, southern hemisphere records of Toarcian carbonate platforms are rare, and thus the extent and significance of biotic platform demise during the T-OAE is unclear. Here we present high-resolution geochemical and sedimentological data across two Pliensbachian-Toarcian shallow-water carbonate-platform sections exposed in the Tibetan Himalaya. These sections were located paleogeographically on the open southeastern tropical Tethyan margin in the southern hemisphere. The T-OAE in the Tibetan Himalaya is marked by a negative CIE in organic matter. Our sedimentological analysis of the two sections reveals an abundance of storm deposits within the T-OAE interval, which emphasizes a close link between warming and tropical storms during the T-OAE event, in line with evidence recently provided from western Tethyan sections of the northern hemisphere. In addition, our analysis also reveals extensive biotic carbonate-platform demise by drowning or changing to non-skeletal carbonates coincident with the onset of the CIE. Taken together, our results suggest that rapid and pervasive seawater warming in response to carbon release likely played a significant role in sudden biotic carbonate platform demise, and suppression/postponement of biotic platform re-development along the whole tropical/subtropical Tethyan margin.

Examining English-German Translation Ambiguity Using Primed Translation Recognition

ERIC Educational Resources Information Center

Eddington, Chelsea M.; Tokowicz, Natasha

2013-01-01

Many words have more than one translation across languages. Such "translation-ambiguous" words are translated more slowly and less accurately than their unambiguous counterparts. We examine the extent to which word context and translation dominance influence the processing of translation-ambiguous words. We further examine how these factors…

The Ambiguity of the Child's "Voice" in Social Research

ERIC Educational Resources Information Center

Komulainen, Sirkka

2007-01-01

This article addresses the ambiguity of the child's "voice" in social research. Drawing on a recent research project on young children's communication difficulties, the author argues that the currently popular discourse on "listening to children" is beset with practical and ethical ambiguities that result from the "socialness" of human…

Quantification Scope Ambiguity Resolution: Evidence from Persian and English

ERIC Educational Resources Information Center

Asadollahfam, Hassan; Lotfi, Ahmad Reza

2010-01-01

This study investigates the interpretation of scopally ambiguous sentences containing noun phrases with double quantified constituents from a processing perspective. The questions this study tried to answer were: whether or not the preferred interpretation for doubly quantified ambiguous sentences in English was influenced by English learners' L1…

Modelling the Effects of Semantic Ambiguity in Word Recognition

ERIC Educational Resources Information Center

Rodd, Jennifer M.; Gaskell, M. Gareth; Marslen-Wilson, William D.

2004-01-01

Most words in English are ambiguous between different interpretations; words can mean different things in different contexts. We investigate the implications of different types of semantic ambiguity for connectionist models of word recognition. We present a model in which there is competition to activate distributed semantic representations. The…

U.S./Arab Reflections on Our Tolerance for Ambiguity

ERIC Educational Resources Information Center

Bright, Larry K.; Mahdi, Ghada S.

2012-01-01

As the authors, a Midwestern American educational administration professor and a Middle Eastern Iraqi doctoral candidate, have continued to interact over the past 3 years, both have come to appreciate the importance of increasing their tolerance for ambiguity--ambiguities in examining cultural, linguistic, and religious customs and complexities in…

To mind the mind: An event-related potential study of word class and semantic ambiguity

PubMed Central

Lee, Chia-lin; Federmeier, Kara D.

2009-01-01

The goal of this study was to jointly examine the effects of word class, word class ambiguity, and semantic ambiguity on the brain response to words in syntactically specified contexts. Four types of words were used: (1) word class ambiguous words with a high degree of semantic ambiguity (e.g., ‘duck’); (2) word class ambiguous words with little or no semantic ambiguity (e.g., ‘vote’); (3) word class unambiguous nouns (e.g., ‘sofa’); and (4) word class unambiguous verbs (e.g., ‘eat’). These words were embedded in minimal phrases that explicitly specified their word class: “the” for nouns (and ambiguous words used as nouns) and “to” for verbs (and ambiguous words used as verbs). Our results replicate the basic word class effects found in prior work (Federmeier, K.D., Segal, J.B., Lombrozo, T., Kutas, M., 2000. Brain responses to nouns, verbs and class ambiguous words in context. Brain, 123 (12), 2552–2566), including an enhanced N400 (250–450ms) to nouns compared with verbs and an enhanced frontal positivity (300–700 ms) to unambiguous verbs in relation to unambiguous nouns. A sustained frontal negativity (250–900 ms) that was previously linked to word class ambiguity also appeared in this study but was specific to word class ambiguous items that also had a high level of semantic ambiguity; word class ambiguous items without semantic ambiguity, in contrast, were more positive than class unambiguous words in the early part of this time window (250–500 ms). Thus, this frontal negative effect seems to be driven by the need to resolve the semantic ambiguity that is sometimes associated with different grammatical uses of a word class ambiguous homograph rather than by the class ambiguity per se. PMID:16516169

Phase ambiguity resolution for offset QPSK modulation systems

NASA Technical Reports Server (NTRS)

Nguyen, Tien M. (Inventor)

1991-01-01

A demodulator for Offset Quaternary Phase Shift Keyed (OQPSK) signals modulated with two words resolves eight possible combinations of phase ambiguity which may produce data error by first processing received I(sub R) and Q(sub R) data in an integrated carrier loop/symbol synchronizer using a digital Costas loop with matched filters for correcting four of eight possible phase lock errors, and then the remaining four using a phase ambiguity resolver which detects the words to not only reverse the received I(sub R) and Q(sub R) data channels, but to also invert (complement) the I(sub R) and/or Q(sub R) data, or to at least complement the I(sub R) and Q(sub R) data for systems using nontransparent codes that do not have rotation direction ambiguity.

Semantic Ambiguity: Do Multiple Meanings Inhibit or Facilitate Word Recognition?

PubMed

Haro, Juan; Ferré, Pilar

2018-06-01

It is not clear whether multiple unrelated meanings inhibit or facilitate word recognition. Some studies have found a disadvantage for words having multiple meanings with respect to unambiguous words in lexical decision tasks (LDT), whereas several others have shown a facilitation for such words. In the present study, we argue that these inconsistent findings may be due to the approach employed to select ambiguous words across studies. To address this issue, we conducted three LDT experiments in which we varied the measure used to classify ambiguous and unambiguous words. The results suggest that multiple unrelated meanings facilitate word recognition. In addition, we observed that the approach employed to select ambiguous words may affect the pattern of experimental results. This evidence has relevant implications for theoretical accounts of ambiguous words processing and representation.

Children's Understanding of Ambiguous Idioms and Conversational Perspective-Taking

ERIC Educational Resources Information Center

Le Sourn-Bissaoui, Sandrine; Caillies, Stephanie; Bernard, Stephane; Deleau, Michel; Brule, Lauriane

2012-01-01

The aim of this study was to test the hypothesis that conversational perspective-taking is a determinant of unfamiliar ambiguous idiom comprehension. We investigated two types of ambiguous idiom, decomposable and nondecomposable expressions, which differ in the degree to which the literal meanings of the individual words contribute to the overall…

Instructor Strategic Ambiguity: Delineation of the Construct and Development of a Measure

ERIC Educational Resources Information Center

Klyukovski, Andrei A.; Medlock-Klyukovski, Amanda L.

2016-01-01

This article presents research to delineate the construct of instructor strategic ambiguity (ISA) and develop a measure. The first study analyzed instructor uses of ambiguity, identified 18 strategies, and classified them into four categories. The second study developed an Instructor Strategic Ambiguity Measure (ISAM) for the college classroom.…

Human Perception of Ambiguous Inertial Motion Cues

NASA Technical Reports Server (NTRS)

Zhang, Guan-Lu

2010-01-01

Human daily activities on Earth involve motions that elicit both tilt and translation components of the head (i.e. gazing and locomotion). With otolith cues alone, tilt and translation can be ambiguous since both motions can potentially displace the otolithic membrane by the same magnitude and direction. Transitions between gravity environments (i.e. Earth, microgravity and lunar) have demonstrated to alter the functions of the vestibular system and exacerbate the ambiguity between tilt and translational motion cues. Symptoms of motion sickness and spatial disorientation can impair human performances during critical mission phases. Specifically, Space Shuttle landing records show that particular cases of tilt-translation illusions have impaired the performance of seasoned commanders. This sensorimotor condition is one of many operational risks that may have dire implications on future human space exploration missions. The neural strategy with which the human central nervous system distinguishes ambiguous inertial motion cues remains the subject of intense research. A prevailing theory in the neuroscience field proposes that the human brain is able to formulate a neural internal model of ambiguous motion cues such that tilt and translation components can be perceptually decomposed in order to elicit the appropriate bodily response. The present work uses this theory, known as the GIF resolution hypothesis, as the framework for experimental hypothesis. Specifically, two novel motion paradigms are employed to validate the neural capacity of ambiguous inertial motion decomposition in ground-based human subjects. The experimental setup involves the Tilt-Translation Sled at Neuroscience Laboratory of NASA JSC. This two degree-of-freedom motion system is able to tilt subjects in the pitch plane and translate the subject along the fore-aft axis. Perception data will be gathered through subject verbal reports. Preliminary analysis of perceptual data does not indicate that

The Ambiguous Dying Syndrome

ERIC Educational Resources Information Center

Bern-Klug, Mercedes

2004-01-01

More than one-half of the 2.4 million deaths that will occur in the United States in 2004 will be immediately preceded by a time in which the likelihood of dying can best be described as "ambiguous." Many people die without ever being considered "dying" or "at the end of life." These people may miss out on the…

Ambiguous genitalia in the newborn: an overview and teaching tool.

PubMed

Murphy, Carla; Allen, L; Jamieson, Mary Anne

2011-10-01

Ambiguous genitalia is a significant example of a disorder of sexual development, in which the external genitalia do not have the typical appearance of either sex. Although the birth of a child with ambiguous genitalia is rare, the emergent nature of the issue demands that healthcare providers have at least a familiarity with the underlying etiologies, the issues, and the initial approach to diagnosis and management. With numerous etiologies, potential difficulties with reaching a diagnosis, and many challenges with immediate and long-term care, the topic of ambiguous genitalia can be daunting. We provide a review of basic embryology, as well as a classification system for understanding the various etiological causes of ambiguous genitalia. The important clinical aspects of diagnosis and management are also highlighted, and a teaching tool has been included to help the reader (or their learners) to solidify information presented. Our overall goal is to provide practical information on ambiguous genitalia and allow the clinician to apply this information to clinically relevant scenarios. Copyright © 2011 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Resolving the ambiguity: Making sense of intrinsic disorder when PDB structures disagree.

PubMed

DeForte, Shelly; Uversky, Vladimir N

2016-03-01

Missing regions in X-ray crystal structures in the Protein Data Bank (PDB) have played a foundational role in the study of intrinsically disordered protein regions (IDPRs), especially in the development of in silico predictors of intrinsic disorder. However, a missing region is only a weak indication of intrinsic disorder, and this uncertainty is compounded by the presence of ambiguous regions, where more than one structure of the same protein sequence "disagrees" in terms of the presence or absence of missing residues. The question is this: are these ambiguous regions intrinsically disordered, or are they the result of static disorder that arises from experimental conditions, ensembles of structures, or domain wobbling? A novel way of looking at ambiguous regions in terms of the pattern between multiple PDB structures has been demonstrated. It was found that the propensity for intrinsic disorder increases as the level of ambiguity decreases. However, it is also shown that ambiguity is more likely to occur as the protein region is placed within different environmental conditions, and even the most ambiguous regions as a set display compositional bias that suggests flexibility. The results suggested that ambiguity is a natural result for many IDPRs crystallized under different conditions and that static disorder and wobbling domains are relatively rare. Instead, it is more likely that ambiguity arises because many of these regions were conditionally or partially disordered. © 2016 The Protein Society.

Synthetic aperture radar range - Azimuth ambiguity design and constraints

NASA Technical Reports Server (NTRS)

Mehlis, J. G.

1980-01-01

Problems concerning the design of a system for mapping a planetary surface with a synthetic aperture radar (SAR) are considered. Given an ambiguity level, resolution, and swath width, the problems are related to the determination of optimum antenna apertures and the most suitable pulse repetition frequency (PRF). From the set of normalized azimuth ambiguity ratio curves, the designer can arrive at the azimuth antenna length, and from the sets of normalized range ambiguity ratio curves, he can arrive at the range aperture length or pulse repetition frequency. A procedure based on this design method is shown in an example. The normalized curves provide results for a SAR using a uniformly or cosine weighted rectangular antenna aperture.

Boundary Ambiguity in Parents with Chronically Ill Children: Integrating Theory and Research

ERIC Educational Resources Information Center

Berge, Jerica M.; Holm, Kristen E.

2007-01-01

This article integrates theory and research related to boundary ambiguity in parents of children with a chronic health condition. We propose that boundary ambiguity is a risk factor for psychological distress in these parents. Clinical applications and a case example highlight how boundary ambiguity can be assessed and managed in clinical settings…

The known unknowns: neural representation of second-order uncertainty, and ambiguity

PubMed Central

Bach, Dominik R.; Hulme, Oliver; Penny, William D.; Dolan, Raymond J.

2011-01-01

Predictions provided by action-outcome probabilities entail a degree of (first-order) uncertainty. However, these probabilities themselves can be imprecise and embody second-order uncertainty. Tracking second-order uncertainty is important for optimal decision making and reinforcement learning. Previous functional magnetic resonance imaging investigations of second-order uncertainty in humans have drawn on an economic concept of ambiguity, where action-outcome associations in a gamble are either known (unambiguous) or completely unknown (ambiguous). Here, we relaxed the constraints associated with a purely categorical concept of ambiguity and varied the second-order uncertainty of gambles continuously, quantified as entropy over second-order probabilities. We show that second-order uncertainty influences decisions in a pessimistic way by biasing second-order probabilities, and that second-order uncertainty is negatively correlated with posterior cingulate cortex activity. The category of ambiguous (compared to non-ambiguous) gambles also biased choice in a similar direction, but was associated with distinct activation of a posterior parietal cortical area; an activation that we show reflects a different computational mechanism. Our findings indicate that behavioural and neural responses to second-order uncertainty are distinct from those associated with ambiguity and may call for a reappraisal of previous data. PMID:21451019

Top-Down Influence in Young Children's Linguistic Ambiguity Resolution

ERIC Educational Resources Information Center

Rabagliati, Hugh; Pylkkanen, Liina; Marcus, Gary F.

2013-01-01

Language is rife with ambiguity. Do children and adults meet this challenge in similar ways? Recent work suggests that while adults resolve syntactic ambiguities by integrating a variety of cues, children are less sensitive to top-down evidence. We test whether this top-down insensitivity is specific to syntax or a general feature of children's…

Pericentric Inversion of Chromosome 9 in an Infant With Ambiguous Genitalia.

PubMed

Sotoudeh, Arya; Rostami, Parastoo; Nakhaeimoghadam, Maryam; Mohsenipour, Reihaneh; Rezaei, Nima

2017-10-01

Pericentric inversion of Chromosome 9 is one of the most common chromosomal abnormalities, which could be associated with various manifestations in some cases. Herein, a patient is presented with ambiguous genitalia that karyotyping revealed pericentric inversion of Chromosome 9 (p12,q13). Pericentric inversion of Chromosome 9 could be considered in the list of differential diagnosis of those with ambiguous genitalia, while chromosomal karyotype and culture could be recommended in children with ambiguous genitalia.

A study of potential sources of linguistic ambiguity in written work instructions.

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

Matzen, Laura E.

This report describes the results of a small experimental study that investigated potential sources of ambiguity in written work instructions (WIs). The English language can be highly ambiguous because words with different meanings can share the same spelling. Previous studies in the nuclear weapons complex have shown that ambiguous WIs can lead to human error, which is a major cause for concern. To study possible sources of ambiguity in WIs, we determined which of the recommended action verbs in the DOE and BWXT writer's manuals have numerous meanings to their intended audience, making them potentially ambiguous. We used cognitive psychologymore » techniques to conduct a survey in which technicians who use WIs in their jobs indicated the first meaning that came to mind for each of the words. Although the findings of this study are limited by the small number of respondents, we identified words that had many different meanings even within this limited sample. WI writers should pay particular attention to these words and to their most frequent meanings so that they can avoid ambiguity in their writing.« less

A Two-Dimensional Variational Analysis Method for NSCAT Ambiguity Removal: Methodology, Sensitivity, and Tuning

NASA Technical Reports Server (NTRS)

Hoffman, R. N.; Leidner, S. M.; Henderson, J. M.; Atlas, R.; Ardizzone, J. V.; Bloom, S. C.; Atlas, Robert (Technical Monitor)

2001-01-01

In this study, we apply a two-dimensional variational analysis method (2d-VAR) to select a wind solution from NASA Scatterometer (NSCAT) ambiguous winds. 2d-VAR determines a "best" gridded surface wind analysis by minimizing a cost function. The cost function measures the misfit to the observations, the background, and the filtering and dynamical constraints. The ambiguity closest in direction to the minimizing analysis is selected. 2d-VAR method, sensitivity and numerical behavior are described. 2d-VAR is compared to statistical interpolation (OI) by examining the response of both systems to a single ship observation and to a swath of unique scatterometer winds. 2d-VAR is used with both NSCAT ambiguities and NSCAT backscatter values. Results are roughly comparable. When the background field is poor, 2d-VAR ambiguity removal often selects low probability ambiguities. To avoid this behavior, an initial 2d-VAR analysis, using only the two most likely ambiguities, provides the first guess for an analysis using all the ambiguities or the backscatter data. 2d-VAR and median filter selected ambiguities usually agree. Both methods require horizontal consistency, so disagreements occur in clumps, or as linear features. In these cases, 2d-VAR ambiguities are often more meteorologically reasonable and more consistent with satellite imagery.

Selection of optimum median-filter-based ambiguity removal algorithm parameters for NSCAT. [NASA scatterometer

NASA Technical Reports Server (NTRS)

Shaffer, Scott; Dunbar, R. Scott; Hsiao, S. Vincent; Long, David G.

1989-01-01

The NASA Scatterometer, NSCAT, is an active spaceborne radar designed to measure the normalized radar backscatter coefficient (sigma0) of the ocean surface. These measurements can, in turn, be used to infer the surface vector wind over the ocean using a geophysical model function. Several ambiguous wind vectors result because of the nature of the model function. A median-filter-based ambiguity removal algorithm will be used by the NSCAT ground data processor to select the best wind vector from the set of ambiguous wind vectors. This process is commonly known as dealiasing or ambiguity removal. The baseline NSCAT ambiguity removal algorithm and the method used to select the set of optimum parameter values are described. An extensive simulation of the NSCAT instrument and ground data processor provides a means of testing the resulting tuned algorithm. This simulation generates the ambiguous wind-field vectors expected from the instrument as it orbits over a set of realistic meoscale wind fields. The ambiguous wind field is then dealiased using the median-based ambiguity removal algorithm. Performance is measured by comparison of the unambiguous wind fields with the true wind fields. Results have shown that the median-filter-based ambiguity removal algorithm satisfies NSCAT mission requirements.

Essentialist thinking predicts decrements in children's memory for racially ambiguous faces.

PubMed

Gaither, Sarah E; Schultz, Jennifer R; Pauker, Kristin; Sommers, Samuel R; Maddox, Keith B; Ambady, Nalini

2014-02-01

Past research shows that adults often display poor memory for racially ambiguous and racial outgroup faces, with both face types remembered worse than own-race faces. In the present study, the authors examined whether children also show this pattern of results. They also examined whether emerging essentialist thinking about race predicts children's memory for faces. Seventy-four White children (ages 4-9 years) completed a face-memory task comprising White, Black, and racially ambiguous Black-White faces. Essentialist thinking about race was also assessed (i.e., thinking of race as immutable and biologically based). White children who used essentialist thinking showed the same bias as White adults: They remembered White faces significantly better than they remembered ambiguous and Black faces. However, children who did not use essentialist thinking remembered both White and racially ambiguous faces significantly better than they remembered Black faces. This finding suggests a specific shift in racial thinking wherein the boundaries between racial groups become more discrete, highlighting the importance of how race is conceptualized in judgments of racially ambiguous individuals.

Ambiguity Tolerance and Perceptual Learning Styles of Chinese EFL Learners

ERIC Educational Resources Information Center

Li, Haishan; He, Qingshun

2016-01-01

Ambiguity tolerance and perceptual learning styles are the two influential elements showing individual differences in EFL learning. This research is intended to explore the relationship between Chinese EFL learners' ambiguity tolerance and their preferred perceptual learning styles. The findings include (1) the learners are sensitive to English…

Ambiguity domain-based identification of altered gait pattern in ALS disorder

NASA Astrophysics Data System (ADS)

Sugavaneswaran, L.; Umapathy, K.; Krishnan, S.

2012-08-01

The onset of a neurological disorder, such as amyotrophic lateral sclerosis (ALS), is so subtle that the symptoms are often overlooked, thereby ruling out the option of early detection of the abnormality. In the case of ALS, over 75% of the affected individuals often experience awkwardness when using their limbs, which alters their gait, i.e. stride and swing intervals. The aim of this work is to suitably represent the non-stationary characteristics of gait (fluctuations in stride and swing intervals) in order to facilitate discrimination between normal and ALS subjects. We define a simple-yet-representative feature vector space by exploiting the ambiguity domain (AD) to achieve efficient classification between healthy and pathological gait stride interval. The stride-to-stride fluctuations and the swing intervals of 16 healthy control and 13 ALS-affected subjects were analyzed. Three features that are representative of the gait signal characteristics were extracted from the AD-space and are fed to linear discriminant analysis and neural network classifiers, respectively. Overall, maximum accuracies of 89.2% (LDA) and 100% (NN) were obtained in classifying the ALS gait.

Ambiguity: A new way of thinking about responses to climate change.

PubMed

Fleming, A; Howden, S M

2016-11-15

Diversity, interdisciplinarity and transdisciplinarity are now recognized as vital to tackling wicked problems such as those presented by a changing climate (Nature editorial 2015, Ledford 2015; Dick et al., 2016). Including diverse disciplines in science projects enables a range of different views which often facilitate the creation of innovative solutions. Supporting multiple views and options requires a different way of working beyond traditional reductionist approaches to science, communication and decision-making. To embrace diversity in scientific project teams in order to tackle complex, integrated and urgent issues but to expect singular and linear pathways forward is paradoxical. Much has been written about the need for the scientific community to embrace uncertainty (e.g. Popper, Lempert & Bankes 2005; Lempert et al., 2004; Nelson, Howden & Hayman 2013; Bammer & Smithson 2008). We argue that this in itself will not suffice, and that there is also a need to embrace ambiguity in certain situations. Thus, in this article we explore: (1) what ambiguity is, including the benefits it can offer to climate adaptation in particular, using existing approaches to ambiguity in the arts and humanities as examples (2), we discuss practical meanings of ambiguity in relation to climate change, (3) we propose possible next steps for bringing ambiguity into interdisciplinary practice, and (4) we identify some challenges and necessary preconditions to successfully and appropriately embracing ambiguity. Copyright © 2016 Elsevier B.V. All rights reserved.

The Inhibitory Mechanism in Learning Ambiguous Words in a Second Language

PubMed Central

Lu, Yao; Wu, Junjie; Dunlap, Susan; Chen, Baoguo

2017-01-01

Ambiguous words are hard to learn, yet little is known about what causes this difficulty. The current study aimed to investigate the relationship between the representations of new and prior meanings of ambiguous words in second language (L2) learning, and to explore the function of inhibitory control on L2 ambiguous word learning at the initial stage of learning. During a 4-day learning phase, Chinese–English bilinguals learned 30 novel English words for 30 min per day using bilingual flashcards. Half of the words to be learned were unambiguous (had one meaning) and half were ambiguous (had two semantically unrelated meanings learned in sequence). Inhibitory control was introduced as a subject variable measured by a Stroop task. The semantic representations established for the studied items were probed using a cross-language semantic relatedness judgment task, in which the learned English words served as the prime, and the targets were either semantically related or unrelated to the prime. Results showed that response latencies for the second meaning of ambiguous words were slower than for the first meaning and for unambiguous words, and that performance on only the second meaning of ambiguous words was predicted by inhibitory control ability. These results suggest that, at the initial stage of L2 ambiguous word learning, the representation of the second meaning is weak, probably interfered with by the representation of the prior learned meaning. Moreover, inhibitory control may modulate learning of the new meanings, such that individuals with better inhibitory control may more effectively suppress interference from the first meaning, and thus learn the new meaning more quickly. PMID:28496423

The Inhibitory Mechanism in Learning Ambiguous Words in a Second Language.

PubMed

Lu, Yao; Wu, Junjie; Dunlap, Susan; Chen, Baoguo

2017-01-01

Ambiguous words are hard to learn, yet little is known about what causes this difficulty. The current study aimed to investigate the relationship between the representations of new and prior meanings of ambiguous words in second language (L2) learning, and to explore the function of inhibitory control on L2 ambiguous word learning at the initial stage of learning. During a 4-day learning phase, Chinese-English bilinguals learned 30 novel English words for 30 min per day using bilingual flashcards. Half of the words to be learned were unambiguous (had one meaning) and half were ambiguous (had two semantically unrelated meanings learned in sequence). Inhibitory control was introduced as a subject variable measured by a Stroop task. The semantic representations established for the studied items were probed using a cross-language semantic relatedness judgment task, in which the learned English words served as the prime, and the targets were either semantically related or unrelated to the prime. Results showed that response latencies for the second meaning of ambiguous words were slower than for the first meaning and for unambiguous words, and that performance on only the second meaning of ambiguous words was predicted by inhibitory control ability. These results suggest that, at the initial stage of L2 ambiguous word learning, the representation of the second meaning is weak, probably interfered with by the representation of the prior learned meaning. Moreover, inhibitory control may modulate learning of the new meanings, such that individuals with better inhibitory control may more effectively suppress interference from the first meaning, and thus learn the new meaning more quickly.

Phase-ambiguity resolution for QPSK modulation systems. Part 1: A review

NASA Technical Reports Server (NTRS)

Nguyen, Tien Manh

1989-01-01

Part 1 reviews the current phase-ambiguity resolution techniques for QPSK coherent modulation systems. Here, those known and published methods of resolving phase ambiguity for QPSK with and without Forward-Error-Correcting (FEC) are discussed. The necessary background is provided for a complete understanding of the second part where a new technique will be discussed. An appropriate technique to the Consultative Committee for Space Data Systems (CCSDS) is recommended for consideration in future standards on phase-ambiguity resolution for QPSK coherent modulation systems.

Ambiguous taxa: Effects on the characterization and interpretation of invertebrate assemblages

USGS Publications Warehouse

Cuffney, T.F.; Bilger, Michael D.; Haigler, A.M.

2007-01-01

Damaged and immature specimens often result in macroinvertebrate data that contain ambiguous parent-child pairs (i.e., abundances associated with multiple related levels of the taxonomic hierarchy such as Baetis pluto and the associated ambiguous parent Baetis sp.). The choice of method used to resolve ambiguous parent-child pairs may have a very large effect on the characterization of invertebrate assemblages and the interpretation of responses to environmental change because very large proportions of taxa richness (73-78%) and abundance (79-91%) can be associated with ambiguous parents. To address this issue, we examined 16 variations of 4 basic methods for resolving ambiguous taxa: RPKC (remove parent, keep child), MCWP (merge child with parent), RPMC (remove parent or merge child with parent depending on their abundances), and DPAC (distribute parents among children). The choice of method strongly affected assemblage structure, assemblage characteristics (e.g., metrics), and the ability to detect responses along environmental (urbanization) gradients. All methods except MCWP produced acceptable results when used consistently within a study. However, the assemblage characteristics (e.g., values of assemblage metrics) differed widely depending on the method used, and data should not be combined unless the methods used to resolve ambiguous taxa are well documented and are known to be comparable. The suitability of the methods was evaluated and compared on the basis of 13 criteria that considered conservation of taxa richness and abundance, consistency among samples, methods, and studies, and effects on the interpretation of the data. Methods RPMC and DPAC had the highest suitability scores regardless of whether ambiguous taxa were resolved for each sample separately or for a group of samples. Method MCWP gave consistently poor results. Methods MCWP and DPAC approximate the use of family-level identifications and operational taxonomic units (OTU), respectively. Our

Personality Type, Tolerance of Ambiguity, and Vocabulary Retention in CALL.

ERIC Educational Resources Information Center

Grace, Caroline

1998-01-01

A study (n=181 college students) examined effects of lexical ambiguity in computer-assisted language learning (CALL) on beginning second-language learners, focusing on whether personality type affects retention of second-language vocabulary independent of translation issues and in an ambiguous CALL context. Findings support the need for beginning…

Systematization of ambiguous genitalia.

PubMed

Makiyan, Zograb

2016-10-01

Sex assignment in newborns depends on the anatomy of the external genitalia, despite this stage being the final in embryogenesis. According to the current view, the genital tubercle is the embryonic precursor of penis and clitoris. It originates from mesenchymal tissue, but mesenchymal cells are arranged across the embryonal body and do not have specific androgen receptors. The nature of the signal that initiates early derivation of the indifferent genital tubercle is unknown at present. The aims of this article are to improve surgical management of intersex disorders and investigate the development of the genital tubercle. Clinical examination of 114 females with various forms of DSD revealed ambiguous (bisexual) external genitalia in 73 patients, and 51 of them underwent feminizing surgery. Intersexuality (ambiguity) in 46,XY patients results from disruptors in the pathways of sex steroid hormones or receptors; in 46,XX females arises from excessive levels of androgens. Systematization of intersex disorders distinguishes the karyotype, gonadal morphology, and genital anatomy to provide a differential diagnosis and guide appropriate surgical management. Modified feminizing clitoroplasty with preservation of the dorsal and ventral neurovascular bundles to retain erogenous sensitivity was performed in females with severe virilization (Prader degree III-V). The outgrowth of the genital tubercle and the fusion of the urethral fold proceed in an ordered fashion; but in some cases of ambiguity, there was discordance due to different pathways. Speculation about the derivation of the genital tubercle have discussed with a literature review. The genital tubercle derives from the following 3 layers: the ectodermal glans of the tubercle, the mesodermal corpora cavernosa and the endodermal urogenital groove. According to the new hypothesis, during the indifferent stages, the 5 sacral somites have to recede from their segmentation and disintegrate: the sclerotomes form the

Detecting depth gradients in the mid-Cretaceous Western Interior Seaway

NASA Astrophysics Data System (ADS)

Bryant, R.

2017-12-01

Multivariate data sets can be simplified using techniques like ordination and detrended correspondence analysis to identify important ecological gradients such as water depth, and thus provide insight into the environmental distribution of species (Patzkowsky & Holland, 2012). Here, these methods will be applied to abundance data of foraminiferal assemblages from the Western Interior Seaway through the Cenomanian/Turonian boundary ( 94-93 Ma). Through this interval the seaway experienced rapid and abrupt environmental and oceanographic changes, including the onset of Oceanic Anoxic Event 2 (OAE2) and peak transgression. The intense ocean and biosphere changes are well documented in the WIS, but the effect of OAE2 coupled with rising sea level on foraminiferal communities across the seaway is still poorly understood.

Another Kind of Ambiguous Loss: Seventh-Day Adventist Women in Mixed-Orientation Marriages

ERIC Educational Resources Information Center

Hernandez, Barbara C.; Wilson, Colwick M.

2007-01-01

Narratives of five Seventh-day Adventist heterosexual women whose mixed-orientation marriages ended were analyzed through the lens of ambiguous loss. Thematic coding identified a wave-like process of changing emotional foci that emerged from their experience during marital dissolution. Elements of ambiguous loss included boundary ambiguity,…

Theory-Based Evaluation Meets Ambiguity: The Role of Janus Variables

ERIC Educational Resources Information Center

Dahler-Larsen, Peter

2018-01-01

As theory-based evaluation (TBE) engages in situations where multiple stakeholders help develop complex program theory about dynamic phenomena in politically contested settings, it becomes difficult to develop and use program theory without ambiguity. The purpose of this article is to explore ambiguity as a fruitful perspective that helps TBE face…

Removing Ambiguities In Remotely Sensed Winds

NASA Technical Reports Server (NTRS)

Shaffer, Scott J.; Dunbar, Roy S.; Hsiao, Shuchi V.; Long, David G.

1991-01-01

Algorithm removes ambiguities in choices of candidate ocean-surface wind vectors estimated from measurements of radar backscatter from ocean waves. Increases accuracies of estimates of winds without requiring new instrumentation. Incorporates vector-median filtering function.

Identification and Definition of Lexically Ambiguous Words in Statistics by Tutors and Students

ERIC Educational Resources Information Center

Richardson, Alice M.; Dunn, Peter K.; Hutchins, Rene

2013-01-01

Lexical ambiguity arises when a word from everyday English is used differently in a particular discipline, such as statistics. This paper reports on a project that begins by identifying tutors' perceptions of words that are potentially lexically ambiguous to students, in two different ways. Students' definitions of nine lexically ambiguous words…

Lexical Access for Phonetic Ambiguities.

ERIC Educational Resources Information Center

Spencer, N. J.; Wollman, Neil

1980-01-01

Reports on research that (1) suggests that phonetically ambiguous pairs (ice cream/I scream) have been used inaccurately to illustrate contextual effects in word segmentation, (2) supports unitary rather than exhaustive processing, and (3) supports the use of the concepts of word frequency and listener expectations instead of top-down, multiple…

Ambiguity Resolution in Lateralized Arabic

ERIC Educational Resources Information Center

Hayadre, Manar; Kurzon, Dennis; Peleg, Orna; Zohar, Eviatar

2015-01-01

We examined ambiguity resolution in reading in Arabic. Arabic is an abjad orthography and is morphologically similar to Hebrew. However, Arabic literacy occurs in a diglossic context, and its orthography is more visually complex than Hebrew. We therefore tested to see whether hemispheric differences will be similar or different from previous…

Spectral Ambiguity of Allan Variance

NASA Technical Reports Server (NTRS)

Greenhall, C. A.

1996-01-01

We study the extent to which knowledge of Allan variance and other finite-difference variances determines the spectrum of a random process. The variance of first differences is known to determine the spectrum. We show that, in general, the Allan variance does not. A complete description of the ambiguity is given.

Robust Ambiguity Estimation for an Automated Analysis of the Intensive Sessions

NASA Astrophysics Data System (ADS)

Kareinen, Niko; Hobiger, Thomas; Haas, Rüdiger

2016-12-01

Very Long Baseline Interferometry (VLBI) is a unique space-geodetic technique that can directly determine the Earth's phase of rotation, namely UT1. The daily estimates of the difference between UT1 and Coordinated Universal Time (UTC) are computed from one-hour long VLBI Intensive sessions. These sessions are essential for providing timely UT1 estimates for satellite navigation systems. To produce timely UT1 estimates, efforts have been made to completely automate the analysis of VLBI Intensive sessions. This requires automated processing of X- and S-band group delays. These data often contain an unknown number of integer ambiguities in the observed group delays. In an automated analysis with the c5++ software the standard approach in resolving the ambiguities is to perform a simplified parameter estimation using a least-squares adjustment (L2-norm minimization). We implement the robust L1-norm with an alternative estimation method in c5++. The implemented method is used to automatically estimate the ambiguities in VLBI Intensive sessions for the Kokee-Wettzell baseline. The results are compared to an analysis setup where the ambiguity estimation is computed using the L2-norm. Additionally, we investigate three alternative weighting strategies for the ambiguity estimation. The results show that in automated analysis the L1-norm resolves ambiguities better than the L2-norm. The use of the L1-norm leads to a significantly higher number of good quality UT1-UTC estimates with each of the three weighting strategies.

Ambiguity in Speaking Chemistry and Other STEM Content: Educational Implications

ERIC Educational Resources Information Center

Isaacson, Mick D.; Michaels, Michelle

2015-01-01

Ambiguity in speech is a possible barrier to the acquisition of knowledge for students who have print disabilities (such as blindness, visual impairments, and some specific learning disabilities) and rely on auditory input for learning. Chemistry appears to have considerable potential for being spoken ambiguously and may be a barrier to accessing…

Electrodermal responses during appetitive conditioning are sensitive to contingency instruction ambiguity.

PubMed

van den Akker, Karolien; Nederkoorn, Chantal; Jansen, Anita

2017-08-01

Studies on human appetitive conditioning using food rewards can benefit from including psychophysiological outcome measures. The present study tested whether the skin conductance response can function as a measure of differential responding in an appetitive conditioning paradigm including an acquisition and extinction phase, and examined which time window during a trial is most sensitive to conditioning effects. As a secondary aim, the effects of ambiguous vs. non-ambiguous contingency instructions on conditioned responses (skin conductance responses, US expectancies, chocolate desires, and CS evaluations) were assessed. Results indicated differential skin conductance responses in an anticipatory time window and during unexpected omission of the US in early extinction. Interestingly however, anticipatory responses were only found for participants who received ambiguous contingency instructions - possibly indicating a call for additional processing resources in response to the ambiguous CS+. Further, ambiguous instructions slowed the extinction of US expectancies but did not influence chocolate desires and CS evaluations. It is concluded that skin conductance can function as a sensitive measure of differential responding in appetitive conditioning, though its sensitivity might depend on the specific task context. Copyright © 2017 Elsevier B.V. All rights reserved.

Sequence data - Magnitude and implications of some ambiguities.

NASA Technical Reports Server (NTRS)

Holmquist, R.; Jukes, T. H.

1972-01-01

A stochastic model is applied to the divergence of the horse-pig lineage from a common ansestor in terms of the alpha and beta chains of hemoglobin and fibrinopeptides. The results are compared with those based on the minimum mutation distance model of Fitch (1972). Buckwheat and cauliflower cytochrome c sequences are analyzed to demonstrate their ambiguities. A comparative analysis of evolutionary rates for various proteins of horses and pigs shows that errors of considerable magnitude are introduced by Glx and Asx ambiguities into evolutionary conclusions drawn from sequences of incompletely analyzed proteins.

When in doubt, seize the day? Security values, prosocial values, and proactivity under ambiguity.

PubMed

Grant, Adam M; Rothbard, Nancy P

2013-09-01

Researchers have suggested that both ambiguity and values play important roles in shaping employees' proactive behaviors, but have not theoretically or empirically integrated these factors. Drawing on theories of situational strength and values, we propose that ambiguity constitutes a weak situation that strengthens the relationship between the content of employees' values and their proactivity. A field study of 204 employees and their direct supervisors in a water treatment plant provided support for this contingency perspective. Ambiguity moderated the relationship between employees' security and prosocial values and supervisor ratings of proactivity. Under high ambiguity, security values predicted lower proactivity, whereas prosocial values predicted higher proactivity. Under low ambiguity, values were not associated with proactivity. We replicated these findings in a laboratory experiment with 232 participants in which we measured proactivity objectively as initiative taken to correct errors: Participants with strong security values were less proactive, and participants with strong prosocial values were more proactive, but only when performance expectations were ambiguous. We discuss theoretical implications for research on proactivity, values, and ambiguity and uncertainty. PsycINFO Database Record (c) 2013 APA, all rights reserved

Working memory constraints on the processing of syntactic ambiguity.

PubMed

MacDonald, M C; Just, M A; Carpenter, P A

1992-01-01

We propose a model that explains how the working-memory capacity of a comprehender can constrain syntactic parsing and thereby affect the processing of syntactic ambiguities. The model's predictions are examined in four experiments that measure the reading times for two constructions that contain a temporary syntactic ambiguity. An example of the syntactic ambiguity is The soldiers warned about the dangers . . . ; the verb warned may either be the main verb, in which case soldiers is the agent; or the verb warned may introduce a relative clause, in which case soldiers is the patient of warned rather than the agent, as in The soldiers warned about the dangers conducted the midnight raid. The model proposes that both alternative interpretations of warned are initially activated. However, the duration for which both interpretations are maintained depends, in part, on the reader's working-memory capacity, which can be assessed by the Reading Span task (Daneman & Carpenter, 1980). The word-by-word reading times indicate that all subjects do additional processing after encountering an ambiguity, suggesting that they generate both representations. Furthermore, readers with larger working-memory capacities maintain both representations for some period of time (several words), whereas readers with smaller working-memory capacities revert to maintaining only the more likely representation.

Testosterone and Cortisol Jointly Predict the Ambiguity Premium in an Ellsberg-Urns Experiment.

PubMed

Danese, Giuseppe; Fernandes, Eugénia; Watson, Neil V; Zilioli, Samuele

2017-01-01

Previous literature has tried to establish whether and how steroid hormones are related to economic risk-taking. In this study, we investigate the relationship between testosterone (T) and cortisol (C) on one side and attitudes toward risk and ambiguity on the other. We asked 78 male undergraduate students to complete several tasks and provide two saliva samples. In the task "Reveal the Bag," participants expressed their beliefs on an ambiguous situation in an incentivized framework. In the task "Ellsberg Bags," we elicited from the participants through an incentive-compatible mechanism the reservation prices for a risky bet and an ambiguous bet. We used the difference between the two prices to calculate each participant's ambiguity premium. We found that participants' salivary T and C levels jointly predicted the ambiguity premium. Participants featuring comparatively lower levels of T and C showed the highest levels of ambiguity aversion. The beliefs expressed by a subset of participants in the "Reveal the Bag" task rationalize (in a revealed preference sense) their choices in the "Ellsberg Bags" task.

Testosterone and Cortisol Jointly Predict the Ambiguity Premium in an Ellsberg-Urns Experiment

PubMed Central

Danese, Giuseppe; Fernandes, Eugénia; Watson, Neil V.; Zilioli, Samuele

2017-01-01

Previous literature has tried to establish whether and how steroid hormones are related to economic risk-taking. In this study, we investigate the relationship between testosterone (T) and cortisol (C) on one side and attitudes toward risk and ambiguity on the other. We asked 78 male undergraduate students to complete several tasks and provide two saliva samples. In the task “Reveal the Bag,” participants expressed their beliefs on an ambiguous situation in an incentivized framework. In the task “Ellsberg Bags,” we elicited from the participants through an incentive-compatible mechanism the reservation prices for a risky bet and an ambiguous bet. We used the difference between the two prices to calculate each participant's ambiguity premium. We found that participants' salivary T and C levels jointly predicted the ambiguity premium. Participants featuring comparatively lower levels of T and C showed the highest levels of ambiguity aversion. The beliefs expressed by a subset of participants in the “Reveal the Bag” task rationalize (in a revealed preference sense) their choices in the “Ellsberg Bags” task. PMID:28484379

GNSS triple-frequency geometry-free and ionosphere-free track-to-track ambiguities

NASA Astrophysics Data System (ADS)

Wang, Kan; Rothacher, Markus

2015-06-01

During the last few years, more and more GNSS satellites have become available sending signals on three or even more frequencies. Examples are the GPS Block IIF and the Galileo In-Orbit-Validation (IOV) satellites. Various investigations have been performed to make use of the increasing number of frequencies to find a compromise between eliminating different error sources and minimizing the noise level, including the investigations in the triple-frequency geometry-free (GF) and ionosphere-free (IF) linear combinations, which eliminate all the geometry-related errors and the first-order term of the ionospheric delays. In contrast to the double-difference GF and IF ambiguity resolution, the resolution of the so-called track-to-track GF and IF ambiguities between two tracks of a satellite observed by the same station only requires one receiver and one satellite. Most of the remaining errors like receiver and satellite delays (electronics, cables, etc.) are eliminated, if they are not changing rapidly in time, and the noise level is reduced theoretically by a factor of square root of two compared to double-differences. This paper presents first results concerning track-to-track ambiguity resolution using triple-frequency GF and IF linear combinations based on data from the Multi-GNSS Experiment (MGEX) from April 29 to May 9, 2012 and from December 23 to December 29, 2012. This includes triple-frequency phase and code observations with different combinations of receiver tracking modes. The results show that it is possible to resolve the combined track-to-track ambiguities of the best two triple-frequency GF and IF linear combinations for the Galileo frequency triplet E1, E5b and E5a with more than 99.6% of the fractional ambiguities for the best linear combination being located within ± 0.03 cycles and more than 98.8% of the fractional ambiguities for the second best linear combination within ± 0.2 cycles, while the fractional parts of the ambiguities for the GPS

Psychophsyiological reactivity during uncertainty and ambiguity processing in high and low worriers.

PubMed

Kirschner, Hans; Hilbert, Kevin; Hoyer, Jana; Lueken, Ulrike; Beesdo-Baum, Katja

2016-03-01

Intolerance of uncertainty (IU) has been linked to Generalized Anxiety Disorder (GAD), but studies experimentally manipulating uncertainty have mostly failed to find differences between GAD patients and controls, possible due to a lack of distinction between uncertainty and ambiguity. This study therefore investigated reactivity to ambiguity in addition to uncertainty in high worriers (HW) and low worriers (LW). We hypothesized an interpretation bias between the groups during ambiguity tasks, while uncertainty would facilitate threat processing of subsequent aversive stimuli. HW (N = 23) and LW (N = 23) completed a paradigm comprising the anticipation and perception of pictures with dangerous, safe, or ambiguous content. Anticipatory cues were certain (always correct information about the following picture) or uncertain (no information). Subjective ratings, reaction times and skin conductance responses (SCRs) were recorded. HW rated particularly ambiguous pictures as more aversive and showed longer reaction times to all picture conditions compared to LW. SCRs were also larger in HW compared to LW, particularly during uncertain but also safe anticipation. No group differences were observed during perception of stimuli. All participants were female. HW was used as subclinical phenotype of GAD. Intolerance of ambiguity seems to be related to individual differences in worry and possibly to the development of GAD. Threat-related interpretations differentiating HW and LW occurred particularly for ambiguous pictures but were not accompanied by increased autonomic arousal during the picture viewing. This disparity between subjective rating and arousal may be the result of worrying in response to intolerance of uncertainty, restraining physiological responses. Copyright © 2015 Elsevier Ltd. All rights reserved.

How meaning similarity influences ambiguous word processing: the current state of the literature

PubMed Central

Tokowicz, Natasha

2016-01-01

The majority of words in the English language do not correspond to a single meaning, but rather correspond to two or more unrelated meanings (i.e., are homonyms) or multiple related senses (i.e., are polysemes). It has been proposed that the different types of “semantically-ambiguous words” (i.e., words with more than one meaning) are processed and represented differently in the human mind. Several review papers and books have been written on the subject of semantic ambiguity (e.g., Adriaens, Small, Cottrell, & Tanenhaus, 1988; Burgess & Simpson, 1988; Degani & Tokowicz, 2010; Gorfein, 1989, 2001; Simpson, 1984). However, several more recent studies (e.g., Klein & Murphy, 2001; Klepousniotou, 2002; Klepousniotou & Baum, 2007; Rodd, Gaskell, & Marslen-Wilson, 2002) have investigated the role of the semantic similarity between the multiple meanings of ambiguous words on processing and representation, whereas this was not the emphasis of previous reviews of the literature. In this review, we focus on the current state of the semantic ambiguity literature that examines how different types of ambiguous words influence processing and representation. We analyze the consistent and inconsistent findings reported in the literature and how factors such as semantic similarity, meaning/sense frequency, task, timing, and modality affect ambiguous word processing. We discuss the findings with respect to recent parallel distributed processing (PDP) models of ambiguity processing (Armstrong & Plaut, 2008, 2011; Rodd, Gaskell, & Marslen-Wilson, 2004). Finally, we discuss how experience/instance-based models (e.g., Hintzman, 1986; Reichle & Perfetti, 2003) can inform a comprehensive understanding of semantic ambiguity resolution. PMID:24889119

Semantic Ambiguity and the Process of Generating Meaning From Print

ERIC Educational Resources Information Center

Pexman, Penny M.; Hino, Yasushi; Lupker, Stephen J.

2004-01-01

An ambiguity disadvantage (slower responses for ambiguous words, e.g., bank, than for unambiguous words) has been reported in semantic tasks (L. R. Gottlob, S. D. Goldinger, G. O. Stone, & G. C. Van Orden, 1999; Y. Hino, S. J. Lupker, & P. M. Pexman, 2002; C. D. Piercey & S. Joordens, 2000) and has been attributed to the meaning activation…

Departure from the onset-onset rule.

PubMed

Chow, S L

1994-09-01

Using a signal-detection task, the generality of Turvey's (1973) onset-onset rule was tested in our experiments. After seeing, in succession, (1) one or two letters (target display), (2) a multiletter detection display, and (3) a mask display, subjects decided whether or not the letter or letters in the target display reappeared in the succeeding detection display at different levels of detection-display duration in various situations. The subjects' sensitivity was inconsistent with the onset-onset rule. More specifically, sensitivity increased with increases in display duration within a fixed stimulus onset asynchrony of 150 msec. Display duration, however, had no effect on response bias. Nor was there any interaction between display duration and display size in terms of either sensitivity or response bias. The more complicated relationship between display duration and display size does not invalidate the departure from the onset-onset rule.

Relation of tolerance of ambiguity to global and specific paranormal experience.

PubMed

Houran, J; Williams, C

1998-12-01

We examined the relationship of tolerance of ambiguity to severe global factors and specific types of anomalous or paranormal experience. 107 undergraduate students completed MacDonald's 1970 AT-20 and the Anomalous Experiences Inventory of Kumar, Pekala, and Gallagher. Scores on the five subscales of the Anomalous Experiences Inventory correlated differently with tolerance of ambiguity. Global paranormal beliefs, abilities, experiences, and drug use were positively associated with tolerance of ambiguity, whereas a fear of paranormal experience showed a negative relation. The specific types of anomalous experiences that correlated with tolerance of ambiguity often involved internal or physiological experience, e.g., precognitive dreams, memories of reincarnation, visual apparitions, and vestibular alterations. We generally found no effects of age of sex. These results are consistent with the idea that some paranormal experiences are misattributions of internal experience to external ('paranormal') sources, a process analogous to mechanisms underpinning delusions and hallucinations.

A Mixture Approach to Vagueness and Ambiguity

PubMed Central

Verheyen, Steven; Storms, Gert

2013-01-01

When asked to indicate which items from a set of candidates belong to a particular natural language category inter-individual differences occur: Individuals disagree which items should be considered category members. The premise of this paper is that these inter-individual differences in semantic categorization reflect both ambiguity and vagueness. Categorization differences are said to be due to ambiguity when individuals employ different criteria for categorization. For instance, individuals may disagree whether hiking or darts is the better example of sports because they emphasize respectively whether an activity is strenuous and whether rules apply. Categorization differences are said to be due to vagueness when individuals employ different cut-offs for separating members from non-members. For instance, the decision to include hiking in the sports category or not, may hinge on how strenuous different individuals require sports to be. This claim is supported by the application of a mixture model to categorization data for eight natural language categories. The mixture model can identify latent groups of categorizers who regard different items likely category members (i.e., ambiguity) with categorizers within each of the groups differing in their propensity to provide membership responses (i.e., vagueness). The identified subgroups are shown to emphasize different sets of category attributes when making their categorization decisions. PMID:23667627

The incidence of ototoxicity in child malignancy cases that received carboplatin therapy with otoacoustic emission (OAE) examination

NASA Astrophysics Data System (ADS)

Wibowo, J. K.; Zizlavsky, S.; Suwento, R.; Sjakti, H. A.; Prihartono, J.

2017-08-01

Malignancy is a significant public health problem, both globally and in Indonesia. Chemotherapy is one of the modality in malignancy cases. Carboplatin (cis-diammine-cyclobutanedi-carboxylato platinum) is a second-generation platinum compound that has often been used in the management of cases of malignancies. On the other hand, side effects of cytotoxic drugs need to be considered, especially ototoxic effects. Ototoxicity is dysfunction and damage to the structure of the inner ear that has been caused by drugs or other certain chemicals. The aim of this study is to assess ototoxic effects due to the influence of carboplatin in the cases of children with malignancy. This study uses a serial cross-sectional design to evaluate otoacoustic emission (OAE) signal-to-noise ratio (SNR) change as a result of ototoxic effects and risk factors due to the use of ototoxic carboplatin in the Division of Hematology-Oncology of the Department of Pediatrics at Cipto Mangunkusumo General Hospital in Jakarta, where two of 52 studies’ subjects experienced ototoxicity. In the group were receiving chemotherapy, two (5%) of the 40 subjects has experienced ototoxic events characterized by SNR values less than six, whereas SNR values were not less than six in the group that had not received chemotherapy. Risk factors such as gender, age, carboplatin dose, and cycles of chemotherapy did not have a statistically significant relationship to ototoxity.

Do you like Arcimboldo's? Esthetic appreciation modulates brain activity in solving perceptual ambiguity.

PubMed

Boccia, M; Nemmi, F; Tizzani, E; Guariglia, C; Ferlazzo, F; Galati, G; Giannini, A M

2015-02-01

Esthetic experience is a unique, affectively colored, self-transcending subject-object relationship in which cognitive processing is felt to flow differently than during everyday experiences. Notwithstanding previous multidisciplinary investigations, how esthetic experience modulates perception is still obscure. We used Arcimboldo's ambiguous portraits to assess how the esthetic context organizes ambiguous percepts. The study was carried out using functional magnetic resonance imaging (fMRI) in healthy young volunteers (mean age 25.45; S.D. 4.51; 9 females), during both an explicit esthetic judgment task and an artwork/non-artwork classification task. We show that a distinct neural mechanism in the fusiform gyrus contributes to the esthetic experience of ambiguous portraits, according to the valence of the esthetic experience. Ambiguous artworks eliciting a negative esthetic experience lead to more pronounced activation of the fusiform face areas than ambiguous artworks eliciting a positive esthetic experience. We also found an interaction between task and ambiguity in the right superior parietal lobule. Taken together, our results demonstrate that a neural mechanism in the content-dependent brain regions of face processing underlies the esthetic experience of ambiguous portraits. Furthermore, they suggest that esthetic experience interacts with perceptual qualities of stimuli in the right superior parietal lobe, supporting the idea that esthetic experience arises from the interaction between top-down orienting of attention and bottom-up perceptual facilitation. Copyright © 2014 Elsevier B.V. All rights reserved.

Pipe flow measurements of turbulence and ambiguity using laser-Doppler velocimetry

NASA Technical Reports Server (NTRS)

Berman, N. S.; Dunning, J. W.

1973-01-01

The laser-Doppler ambiguities predicted by George and Lumley (1973) have been verified experimentally for turbulent pipe flows. Experiments were performed at Reynolds numbers from 5000 to 15,000 at the center line and near the wall. Ambiguity levels were measured from power spectral densities of FM demodulated laser signals and were compared with calculations based on the theory. The turbulent spectra for these water flows after accounting for the ambiguity were equivalent to hot-film measurements at similar Reynolds numbers. The feasibility of laser-Doppler measurements very close to the wall in shear flows is demonstrated.

Wind scatterometry with improved ambiguity selection and rain modeling

NASA Astrophysics Data System (ADS)

Draper, David Willis

Although generally accurate, the quality of SeaWinds on QuikSCAT scatterometer ocean vector winds is compromised by certain natural phenomena and retrieval algorithm limitations. This dissertation addresses three main contributors to scatterometer estimate error: poor ambiguity selection, estimate uncertainty at low wind speeds, and rain corruption. A quality assurance (QA) analysis performed on SeaWinds data suggests that about 5% of SeaWinds data contain ambiguity selection errors and that scatterometer estimation error is correlated with low wind speeds and rain events. Ambiguity selection errors are partly due to the "nudging" step (initialization from outside data). A sophisticated new non-nudging ambiguity selection approach produces generally more consistent wind than the nudging method in moderate wind conditions. The non-nudging method selects 93% of the same ambiguities as the nudged data, validating both techniques, and indicating that ambiguity selection can be accomplished without nudging. Variability at low wind speeds is analyzed using tower-mounted scatterometer data. According to theory, below a threshold wind speed, the wind fails to generate the surface roughness necessary for wind measurement. A simple analysis suggests the existence of the threshold in much of the tower-mounted scatterometer data. However, the backscatter does not "go to zero" beneath the threshold in an uncontrolled environment as theory suggests, but rather has a mean drop and higher variability below the threshold. Rain is the largest weather-related contributor to scatterometer error, affecting approximately 4% to 10% of SeaWinds data. A simple model formed via comparison of co-located TRMM PR and SeaWinds measurements characterizes the average effect of rain on SeaWinds backscatter. The model is generally accurate to within 3 dB over the tropics. The rain/wind backscatter model is used to simultaneously retrieve wind and rain from SeaWinds measurements. The simultaneous

Dispositional sources of sanction perceptions: Emotionality, cognitive style, intolerance of ambiguity, and self-efficacy.

PubMed

Pickett, Justin T; Bushway, Shawn D

2015-12-01

This study contributes to efforts to identify the sources of arrest risk perceptions and ambiguity (or lack of confidence) in such perceptions. Drawing on dual-process theories of reasoning, we argue that arrest risk perceptions often represent intuitive judgments that are influenced by cognitive heuristics and dispositional attributes. Multivariate regression models are estimated with data from 3 national surveys to test 6 hypotheses about the relationships between specific dispositional attributes and perceived arrest risk and ambiguity. We find evidence that dispositional positive affect and intolerance of ambiguity are both positively related to perceived arrest risk, and are also both negatively related to ambiguity. We also find evidence that cognitive reflection and general self-efficacy are, respectively, positively and negatively associated with ambiguity. Mixed evidence emerges about whether cognitive reflection is related to risk perceptions, and about whether either dispositional negative affect or thoughtfully reflective decision making correlate with ambiguity. Taken together, the results provide partial support for each of our hypotheses, and suggest that dispositional attributes are important sources of perceptions of arrest risk as well as of ambiguity in such perceptions. (c) 2015 APA, all rights reserved).

Ambiguity Resolution for Phase-Based 3-D Source Localization under Fixed Uniform Circular Array.

PubMed

Chen, Xin; Liu, Zhen; Wei, Xizhang

2017-05-11

Under fixed uniform circular array (UCA), 3-D parameter estimation of a source whose half-wavelength is smaller than the array aperture would suffer from a serious phase ambiguity problem, which also appears in a recently proposed phase-based algorithm. In this paper, by using the centro-symmetry of UCA with an even number of sensors, the source's angles and range can be decoupled and a novel algorithm named subarray grouping and ambiguity searching (SGAS) is addressed to resolve angle ambiguity. In the SGAS algorithm, each subarray formed by two couples of centro-symmetry sensors can obtain a batch of results under different ambiguities, and by searching the nearest value among subarrays, which is always corresponding to correct ambiguity, rough angle estimation with no ambiguity is realized. Then, the unambiguous angles are employed to resolve phase ambiguity in a phase-based 3-D parameter estimation algorithm, and the source's range, as well as more precise angles, can be achieved. Moreover, to improve the practical performance of SGAS, the optimal structure of subarrays and subarray selection criteria are further investigated. Simulation results demonstrate the satisfying performance of the proposed method in 3-D source localization.

Method and apparatus for reducing range ambiguity in synthetic aperture radar

DOEpatents

Kare, Jordin T.

1999-10-26

A modified Synthetic Aperture Radar (SAR) system with reduced sensitivity to range ambiguities, and which uses secondary receiver channels to detect the range ambiguous signals and subtract them from the signal received by the main channel. Both desired and range ambiguous signals are detected by a main receiver and by one or more identical secondary receivers. All receivers are connected to a common antenna with two or more feed systems offset in elevation (e.g., a reflector antenna with multiple feed horns or a phased array with multiple phase shift networks. The secondary receiver output(s) is (are) then subtracted from the main receiver output in such a way as to cancel the ambiguous signals while only slightly attenuating the desired signal and slightly increasing the noise in the main channel, and thus does not significantly affect the desired signal. This subtraction may be done in real time, or the outputs of the receivers may be recorded separately and combined during signal processing.

Systematization of ambiguous genitalia

PubMed Central

Makiyan, Zograb

2016-01-01

ABSTRACT Sex assignment in newborns depends on the anatomy of the external genitalia, despite this stage being the final in embryogenesis. According to the current view, the genital tubercle is the embryonic precursor of penis and clitoris. It originates from mesenchymal tissue, but mesenchymal cells are arranged across the embryonal body and do not have specific androgen receptors. The nature of the signal that initiates early derivation of the indifferent genital tubercle is unknown at present. The aims of this article are to improve surgical management of intersex disorders and investigate the development of the genital tubercle. Clinical examination of 114 females with various forms of DSD revealed ambiguous (bisexual) external genitalia in 73 patients, and 51 of them underwent feminizing surgery. Intersexuality (ambiguity) in 46,XY patients results from disruptors in the pathways of sex steroid hormones or receptors; in 46,XX females arises from excessive levels of androgens. Systematization of intersex disorders distinguishes the karyotype, gonadal morphology, and genital anatomy to provide a differential diagnosis and guide appropriate surgical management. Modified feminizing clitoroplasty with preservation of the dorsal and ventral neurovascular bundles to retain erogenous sensitivity was performed in females with severe virilization (Prader degree III-V). The outgrowth of the genital tubercle and the fusion of the urethral fold proceed in an ordered fashion; but in some cases of ambiguity, there was discordance due to different pathways. Speculation about the derivation of the genital tubercle have discussed with a literature review. The genital tubercle derives from the following 3 layers: the ectodermal glans of the tubercle, the mesodermal corpora cavernosa and the endodermal urogenital groove. According to the new hypothesis, during the indifferent stages, the 5 sacral somites have to recede from their segmentation and disintegrate: the sclerotomes

A Range Ambiguity Suppression Processing Method for Spaceborne SAR with Up and Down Chirp Modulation.

PubMed

Wen, Xuejiao; Qiu, Xiaolan; Han, Bing; Ding, Chibiao; Lei, Bin; Chen, Qi

2018-05-07

Range ambiguity is one of the factors which affect the SAR image quality. Alternately transmitting up and down chirp modulation pulses is one of the methods used to suppress the range ambiguity. However, the defocusing range ambiguous signal can still hold the stronger backscattering intensity than the mainlobe imaging area in some case, which has a severe impact on visual effects and subsequent applications. In this paper, a novel hybrid range ambiguity suppression method for up and down chirp modulation is proposed. The method can obtain the ambiguity area image and reduce the ambiguity signal power appropriately, by applying pulse compression using a contrary modulation rate and CFAR detecting method. The effectiveness and correctness of the approach is demonstrated by processing the archive images acquired by Chinese Gaofen-3 SAR sensor in full-polarization mode.

Are "drink responsibly" alcohol campaigns strategically ambiguous?

PubMed

Smith, Sandi W; Atkin, Charles K; Roznowski, JoAnn

2006-01-01

This article applies the concept of strategic ambiguity in examining viewer responses to brewer-sponsored "responsible drinking" television advertising campaigns. Strategically ambiguous messages are designed to engender diverse interpretations between varied audience segments, and these different selective perceptions should translate into relatively uniform positive corporate images. In this study, teenage and young adult respondents were shown a series of television spots from two leading alcohol companies. As predicted, there was a high degree of diversity in meanings of message content and campaign purpose derived by viewers, particularly among less sophisticated teenagers. Moreover, evaluative ratings of messages and sponsors were generally favorable and more uniform than interpretive responses. The research demonstrates how seemingly prohealth messages can serve to subtly advance both industry sales and public relations interests.

Ambiguities in model-independent partial-wave analysis

NASA Astrophysics Data System (ADS)

Krinner, F.; Greenwald, D.; Ryabchikov, D.; Grube, B.; Paul, S.

2018-06-01

Partial-wave analysis is an important tool for analyzing large data sets in hadronic decays of light and heavy mesons. It commonly relies on the isobar model, which assumes multihadron final states originate from successive two-body decays of well-known undisturbed intermediate states. Recently, analyses of heavy-meson decays and diffractively produced states have attempted to overcome the strong model dependences of the isobar model. These analyses have overlooked that model-independent, or freed-isobar, partial-wave analysis can introduce mathematical ambiguities in results. We show how these ambiguities arise and present general techniques for identifying their presence and for correcting for them. We demonstrate these techniques with specific examples in both heavy-meson decay and pion-proton scattering.

Integer-ambiguity resolution in astronomy and geodesy

NASA Astrophysics Data System (ADS)

Lannes, A.; Prieur, J.-L.

2014-02-01

Recent theoretical developments in astronomical aperture synthesis have revealed the existence of integer-ambiguity problems. Those problems, which appear in the self-calibration procedures of radio imaging, have been shown to be similar to the nearest-lattice point (NLP) problems encountered in high-precision geodetic positioning and in global navigation satellite systems. In this paper we analyse the theoretical aspects of the matter and propose new methods for solving those NLP~problems. The related optimization aspects concern both the preconditioning stage, and the discrete-search stage in which the integer ambiguities are finally fixed. Our algorithms, which are described in an explicit manner, can easily be implemented. They lead to substantial gains in the processing time of both stages. Their efficiency was shown via intensive numerical tests.

More than visual literacy: art and the enhancement of tolerance for ambiguity and empathy.

PubMed

Bentwich, Miriam Ethel; Gilbey, Peter

2017-11-10

Comfort with ambiguity, mostly associated with the acceptance of multiple meanings, is a core characteristic of successful clinicians. Yet past studies indicate that medical students and junior physicians feel uncomfortable with ambiguity. Visual Thinking Strategies (VTS) is a pedagogic approach involving discussions of art works and deciphering the different possible meanings entailed in them. However, the contribution of art to the possible enhancement of the tolerance for ambiguity among medical students has not yet been adequately investigated. We aimed to offer a novel perspective on the effect of art, as it is experienced through VTS, on medical students' tolerance of ambiguity and its possible relation to empathy. Quantitative method utilizing a short survey administered after an interactive VTS session conducted within mandatory medical humanities course for first-year medical students. The intervention consisted of a 90-min session in the form of a combined lecture and interactive discussions about art images. The VTS session and survey were filled by 67 students in two consecutive rounds of first-year students. 67% of the respondents thought that the intervention contributed to their acceptance of multiple possible meanings, 52% thought their visual observation ability was enhanced and 34% thought that their ability to feel the sufferings of other was being enhanced. Statistically significant moderate-to-high correlations were found between the contribution to ambiguity tolerance and contribution to empathy (0.528-0.744; p ≤ 0.01). Art may contribute especially to the development of medical students' tolerance of ambiguity, also related to the enhancement of empathy. The potential contribution of visual art works used in VTS to the enhancement of tolerance for ambiguity and empathy is explained based on relevant literature regarding the embeddedness of ambiguity within art works, coupled with reference to John Dewey's theory of learning. Given the

Sexual Self-Concept Ambiguity and the Interpersonal Theory of Suicide Risk

PubMed Central

Talley, Amelia E.; Brown, Sarah L.; Cukrowicz, Kelly; Bagge, Courtney L.

2015-01-01

Mechanisms (i.e., thwarted belongingness, perceived burdensomeness, hopelessness) derived from the interpersonal theory of suicide which are hypothesized to account for the relation between sexual orientation self-concept ambiguity and active suicide ideation were examined. Participants included 349 women, among whom 42% currently self-ascribed a non-exclusively heterosexual sexual identity. Among women reporting higher levels of sexual self-concept ambiguity, greater risk for active suicide ideation is found when perceptions of burden and feelings of thwarted belonging co-occur with feelings of hopelessness. Results support relevant theory useful for understanding suicide risk among sexual minority women who acknowledge ambiguity with regard to their sexual orientation. PMID:26190166

Understandings of Environmental Quality: Ambiguities and Values Held by Environmental Professionals

Treesearch

R. Bruce Hull; David Richert; Erin Seekamp; David Robertson; Gregory J. Buhyoff

2003-01-01

The terms used to describe and negotiate environmental quality are both ambiguous and value-laden. Stakeholders intimately and actively involved in the management of forested lands were interviewed and found to use ambiguous, tautological, and value-laden definitions of terms such as health, biodiversity, sustainability, and naturalness. This confusing language...

Is ambiguity tolerance malleable? Experimental evidence with potential implications for future research

PubMed Central

Endres, Megan L.; Camp, Richaurd; Milner, Morgan

2015-01-01

We conducted two research studies to address the malleability of tolerance of ambiguity (TA) by manipulating situational ambiguity. Students participated in a semester-end assessment of their management skills (n = 306). In Study 1, students in low and moderate ambiguity conditions had significantly higher post-experiment TA, more positive change in self-efficacy, and marginally higher faculty ratings. In Study 2, a control group (n = 103) did not participate in the assessment and was established for comparison to the first study results. The Study 2 students reported TA significantly lower than Study 1 students in the low and moderate ambiguity conditions. The control group TA was not significantly different from that of the Study 1 high ambiguity condition. This further suggested TA’s situational malleability, as those who had controlled access to structured information appeared to have increased their TA over that observed in the other two groups. These results suggest that TA may be malleable. We review the relevant literature, offer hypotheses, report our analyses and findings, and then propose future research, and potential prescriptive applications in such areas as management development, assessment, and decision-making. PMID:26042059

Is ambiguity tolerance malleable? Experimental evidence with potential implications for future research.

PubMed

Endres, Megan L; Camp, Richaurd; Milner, Morgan

2015-01-01

We conducted two research studies to address the malleability of tolerance of ambiguity (TA) by manipulating situational ambiguity. Students participated in a semester-end assessment of their management skills (n = 306). In Study 1, students in low and moderate ambiguity conditions had significantly higher post-experiment TA, more positive change in self-efficacy, and marginally higher faculty ratings. In Study 2, a control group (n = 103) did not participate in the assessment and was established for comparison to the first study results. The Study 2 students reported TA significantly lower than Study 1 students in the low and moderate ambiguity conditions. The control group TA was not significantly different from that of the Study 1 high ambiguity condition. This further suggested TA's situational malleability, as those who had controlled access to structured information appeared to have increased their TA over that observed in the other two groups. These results suggest that TA may be malleable. We review the relevant literature, offer hypotheses, report our analyses and findings, and then propose future research, and potential prescriptive applications in such areas as management development, assessment, and decision-making.

Size doesn't really matter: ambiguity aversion in Ellsberg urns with few balls.

PubMed

Pulford, Briony D; Colman, Andrew M

2008-01-01

When attempting to draw a ball of a specified color either from an urn containing 50 red balls and 50 black balls or from an urn containing an unknown ratio of 100 red and black balls, a majority of decision makers prefer the known-risk urn, and this ambiguity aversion effect violates expected utility theory. In an experimental investigation of the effect of urn size on ambiguity aversion, 149 participants showed similar levels of aversion when choosing from urns containing 2, 10, or 100 balls. The occurrence of a substantial and significant ambiguity aversion effect even in the smallest urn suggests that influential theoretical interpretations of ambiguity aversion may need to be reconsidered.

A theoretical study on the bottlenecks of GPS phase ambiguity resolution in a CORS RTK Network

NASA Astrophysics Data System (ADS)

Odijk, D.; Teunissen, P.

2011-01-01

Crucial to the performance of GPS Network RTK positioning is that a user receives and applies correction information from a CORS Network. These corrections are necessary for the user to account for the atmospheric (ionospheric and tropospheric) delays and possibly orbit errors between his approximate location and the locations of the CORS Network stations. In order to provide the most precise corrections to users, the CORS Network processing should be based on integer resolution of the carrier phase ambiguities between the network's CORS stations. One of the main challenges is to reduce the convergence time, thus being able to quickly resolve the integer carrier phase ambiguities between the network's reference stations. Ideally, the network ambiguity resolution should be conducted within one single observation epoch, thus truly in real time. Unfortunately, single-epoch CORS Network RTK ambiguity resolution is currently not feasible and in the present contribution we study the bottlenecks preventing this. For current dual-frequency GPS the primary cause of these CORS Network integer ambiguity initialization times is the lack of a sufficiently large number of visible satellites. Although an increase in satellite number shortens the ambiguity convergence times, instantaneous CORS Network RTK ambiguity resolution is not feasible even with 14 satellites. It is further shown that increasing the number of stations within the CORS Network itself does not help ambiguity resolution much, since every new station introduces new ambiguities. The problem with CORS Network RTK ambiguity resolution is the presence of the atmospheric (mainly ionospheric) delays themselves and the fact that there are no external corrections that are sufficiently precise. We also show that external satellite clock corrections hardly contribute to CORS Network RTK ambiguity resolution, despite their quality, since the network satellite clock parameters and the ambiguities are almost completely

Comprehension of Ambiguous and Other Polysemous Utterances: Presented in Written Mode.

ERIC Educational Resources Information Center

Brause, Rita S.

Designed to assess comprehension of written ambiguous and polysemous structures, this instrument is a series of written statements that include varying degrees and types of ambiguity. In the first part of the test students are asked to identify (from a choice of three) semantically acceptable paraphrases for an initial sentence. Then students must…

Are Sex-Role Orientation, Cognitive Style, and Tolerance for Ambiguity Related?

ERIC Educational Resources Information Center

Rotter, Naomi G.; O'Connell, Agnes N.

The relationship between self-described sex roles and two measures of cognitive style (intolerance for ambiguity and level of abstractness-concreteness) were explored. Subjects were 87 male and 204 female college students. The Schroder and Streufert measure of cognitive style, the Budner Intolerance for Ambiguity Scale (1962), and the Bem Sex Role…

Exploiting Lexical Ambiguity to Help Students Understand the Meaning of "Random"

ERIC Educational Resources Information Center

Kaplan, Jennifer J.; Rogness, Neal T.; Fisher, Diane G.

2014-01-01

Words that are part of colloquial English but used differently in a technical domain may possess lexical ambiguity. The use of such words by instructors may inhibit student learning if incorrect connections are made by students between the technical and colloquial meanings. One fundamental word in statistics that has lexical ambiguity for students…

Spreading the Clinical Window for Diagnosing Fetal-Onset Hypogonadism in Boys

PubMed Central

Grinspon, Romina P.; Loreti, Nazareth; Braslavsky, Débora; Valeri, Clara; Schteingart, Helena; Ballerini, María Gabriela; Bedecarrás, Patricia; Ambao, Verónica; Gottlieb, Silvia; Ropelato, María Gabriela; Bergadá, Ignacio; Campo, Stella M.; Rey, Rodolfo A.

2014-01-01

In early fetal development, the testis secretes – independent of pituitary gonadotropins – androgens and anti-Müllerian hormone (AMH) that are essential for male sex differentiation. In the second half of fetal life, the hypothalamic–pituitary axis gains control of testicular hormone secretion. Follicle-stimulating hormone (FSH) controls Sertoli cell proliferation, responsible for testis volume increase and AMH and inhibin B secretion, whereas luteinizing hormone (LH) regulates Leydig cell androgen and INSL3 secretion, involved in the growth and trophism of male external genitalia and in testis descent. This differential regulation of testicular function between early and late fetal periods underlies the distinct clinical presentations of fetal-onset hypogonadism in the newborn male: primary hypogonadism results in ambiguous or female genitalia when early fetal-onset, whereas it becomes clinically undistinguishable from central hypogonadism when established later in fetal life. The assessment of the hypothalamic–pituitary–gonadal axis in male has classically relied on the measurement of gonadotropin and testosterone levels in serum. These hormone levels normally decline 3–6 months after birth, thus constraining the clinical evaluation window for diagnosing male hypogonadism. The advent of new markers of gonadal function has spread this clinical window beyond the first 6 months of life. In this review, we discuss the advantages and limitations of old and new markers used for the functional assessment of the hypothalamic–pituitary–testicular axis in boys suspected of fetal-onset hypogonadism. PMID:24847309

On Ambiguities in SAR Design

NASA Technical Reports Server (NTRS)

Freeman, Anthony

2006-01-01

Ambiguities are an aliasing effect caused by the periodic sampling of the scene backscatter inherent to pulsed radar systems such as Synthetic Aperture radar (SAR). In this paper we take a fresh look at the relationship between SAR range and azimuth ambiguity constraints on the allowable pulse repetition frequency (PRF) and the antenna length. We show that for high squint angles smaller antennas may be feasible in some cases. For some applications, the ability to form a synthetic aperture at high squint angles is desirable, but the size of the antenna causes problems in the design of systems capable of such operation. This is because the SAR system design is optimized for a side-looking geometry. In two examples design examples we take a suboptimum antenna size and examine the performance in terms of azimuth resolution and swath width as a function of squint angle. We show that for stripmap SARs, the swath width is usually worse for off-boresight squint angles, because it is severely limited by range walk, except in cases where we relax the spatial resolution. We consider the implications for the design of modest-resolution, narrow swath, scanning SAR scatterometers .

Model Ambiguities in Configurational Comparative Research

ERIC Educational Resources Information Center

Baumgartner, Michael; Thiem, Alrik

2017-01-01

For many years, sociologists, political scientists, and management scholars have readily relied on Qualitative Comparative Analysis (QCA) for the purpose of configurational causal modeling. However, this article reveals that a severe problem in the application of QCA has gone unnoticed so far: model ambiguities. These arise when multiple causal…

Sexual Self-Concept Ambiguity and the Interpersonal Theory of Suicide Risk.

PubMed

Talley, Amelia E; Brown, Sarah L; Cukrowicz, Kelly; Bagge, Courtney L

2016-04-01

Mechanisms (i.e., thwarted belongingness, perceived burdensomeness, hopelessness) derived from the interpersonal theory of suicide which are hypothesized to account for the relation between sexual orientation self-concept ambiguity and active suicide ideation were examined. Participants included 349 women, among whom 42% currently self-ascribed a non-exclusively heterosexual sexual identity. Among women reporting higher levels of sexual self-concept ambiguity, greater risk for active suicide ideation is found when perceptions of burden and feelings of thwarted belonging co-occur with feelings of hopelessness. Results support relevant theory useful for understanding suicide risk among sexual minority women who acknowledge ambiguity with regard to their sexual orientation. © 2015 The American Association of Suicidology.

The skew ray ambiguity in the analysis of videokeratoscopic data.

PubMed

Iskander, D Robert; Davis, Brett A; Collins, Michael J

2007-05-01

Skew ray ambiguity is present in most videokeratoscopic measurements when azimuthal components of the corneal curvature are not taken into account. There have been some reported studies based on theoretical predictions and measured test surfaces suggesting that skew ray ambiguity is significant for highly deformed corneas or decentered corneal measurements. However, the effect of skew ray ambiguity in ray tracing through videokeratoscopic data has not been studied in depth. We have evaluated the significance of the skew ray ambiguity and its effect on the analyzed corneal optics. This has been achieved by devising a procedure in which we compared the corneal wavefront aberrations estimated from 3D ray tracing with those determined from 2D (meridional based) estimates of the refractive power. The latter was possible due to recently developed concept of refractive Zernike power polynomials which links the refractive power domain with that of the wavefront. Simulated corneal surfaces as well as data from a range of corneas (from two different Placido disk-based videokeratoscopes) were used to find the limit at which the difference in estimated corneal wavefronts (or the corresponding refractive powers) would have clinical significance (e.g., equivalent to 0.125 D or more). The inclusion/exclusion of the skew ray in the analyses showed some differences in the results. However, the proposed procedure showed clinically significant differences only for highly deformed corneas and only for large corneal diameters. For the overwhelming majority of surfaces, the skew ray ambiguity is not a clinically significant issue in the analysis of the videokeratoscopic data indicating that the meridional processing such as that encountered in calculation of the refractive power maps is adequate.

Ambiguous Loss after Lesbian Couples with Children Break up: A Case for Same-Gender Divorce

ERIC Educational Resources Information Center

Allen, Katherine R.

2007-01-01

The theory of ambiguous loss is applied to structural ambiguity and personal transcendence in the parent-child relationship following a same-gender relational ending. Working recursively through the six guidelines of ambiguous loss (finding meaning, tempering mastery, reconstructing identity, normalizing ambivalence, revising attachment, and…

Managing ambiguity in reference generation: the role of surface structure.

PubMed

Khan, Imtiaz H; van Deemter, Kees; Ritchie, Graeme

2012-04-01

This article explores the role of surface ambiguities in referring expressions, and how the risk of such ambiguities should be taken into account by an algorithm that generates referring expressions, if these expressions are to be optimally effective for a hearer. We focus on the ambiguities that arise when adjectives occur in coordinated structures. The central idea is to use statistical information about lexical co-occurrence to estimate which interpretation of a phrase is most likely for human readers, and to avoid generating phrases where misunderstandings are likely. Various aspects of the problem were explored in three experiments in which responses by human participants provided evidence about which reading was most likely for certain phrases, which phrases were deemed most suitable for particular referents, and the speed at which various phrases were read. We found a preference for ''clear'' expressions to ''unclear'' ones, but if several of the expressions are ''clear,'' then brief expressions are preferred over non-brief ones even though the brief ones are syntactically ambiguous and the non-brief ones are not; the notion of clarity was made precise using Kilgarriff's Word Sketches. We outline an implemented algorithm that generates noun phrases conforming to our hypotheses. Copyright © 2011 Cognitive Science Society, Inc.

Children "tune out" in response to the ambiguous communication style of powerless adults.

PubMed

Bugental, D B; Lyon, J E; Lin, E K; McGrath, E P; Bimbela, A

1999-01-01

Changes in children's attentional engagement were assessed as a function of their exposure to "teachers" who differed in perceived power and the communication style that is associated with perceived power. In Study 1, "teachers" (women assigned to an instructional role) were selected on the basis of their perceived power; low-power women were more likely than high-power women to display communication ambiguity. Children responded to low-power women with low levels of (1) autonomic orienting (consistent with low attention) and (2) high errors on a cognitively demanding task (mental arithmetic). Attentional disengagement was found to be mediated by the ambiguous communication style of low-power adults. In Study 2, the "teacher" was a confederate who systematically varied the facial and vocal ambiguity of her instructions. Children showed the lowest levels of orienting and the highest level of errors when the "teacher" was ambiguous in both face and voice. Results were interpreted as showing that adult ambiguity (naturally occurring or experimentally produced) leads to reductions in children's attentional engagement.

Ego depletion in visual perception: Ego-depleted viewers experience less ambiguous figure reversal.

PubMed

Wimmer, Marina C; Stirk, Steven; Hancock, Peter J B

2017-10-01

This study examined the effects of ego depletion on ambiguous figure perception. Adults (N = 315) received an ego depletion task and were subsequently tested on their inhibitory control abilities that were indexed by the Stroop task (Experiment 1) and their ability to perceive both interpretations of ambiguous figures that was indexed by reversal (Experiment 2). Ego depletion had a very small effect on reducing inhibitory control (Cohen's d = .15) (Experiment 1). Ego-depleted participants had a tendency to take longer to respond in Stroop trials. In Experiment 2, ego depletion had small to medium effects on the experience of reversal. Ego-depleted viewers tended to take longer to reverse ambiguous figures (duration to first reversal) when naïve of the ambiguity and experienced less reversal both when naïve and informed of the ambiguity. Together, findings suggest that ego depletion has small effects on inhibitory control and small to medium effects on bottom-up and top-down perceptual processes. The depletion of cognitive resources can reduce our visual perceptual experience.

The Development of Ambiguous Figure Perception

ERIC Educational Resources Information Center

Wimmer, Marina C.; Doherty, Martin J.

2011-01-01

Ambiguous figures have fascinated researchers for almost 200 years. The physical properties of these figures remain constant, yet two distinct interpretations are possible; these reverse (switch) from one percept to the other. The consensus is that reversal requires complex interaction of perceptual bottom-up and cognitive top-down elements. The…

The inertial attitude augmentation for ambiguity resolution in SF/SE-GNSS attitude determination.

PubMed

Zhu, Jiancheng; Hu, Xiaoping; Zhang, Jingyu; Li, Tao; Wang, Jinling; Wu, Meiping

2014-06-26

The Unaided Single Frequency/Single Epoch Global Navigation Satellite System (SF/SE GNSS) model is the most challenging scenario for ambiguity resolution in the GNSS attitude determination application. To improve the performance of SF/SE-GNSS ambiguity resolution without excessive cost, the Micro-Electro-Mechanical System Inertial Measurement Unit (MEMS-IMU) is a proper choice for the auxiliary sensor that carries out the inertial attitude augmentation. Firstly, based on the SF/SE-GNSS compass model, the Inertial Derived Baseline Vector (IDBV) is defined to connect the MEMS-IMU attitude measurement with the SF/SE-GNSS ambiguity search space, and the mechanism of inertial attitude augmentation is revealed from the perspective of geometry. Then, through the quantitative description of model strength by Ambiguity Dilution of Precision (ADOP), two ADOPs are specified for the unaided SF/SE-GNSS compass model and its inertial attitude augmentation counterparts, respectively, and a sufficient condition is proposed for augmenting the SF/SE-GNSS model strength with inertial attitude measurement. Finally, in the framework of an integer aperture estimator with fixed failure rate, the performance of SF/SE-GNSS ambiguity resolution with inertial attitude augmentation is analyzed when the model strength is varying from strong to weak. The simulation results show that, in the SF/SE-GNSS attitude determination application, MEMS-IMU can satisfy the requirements of ambiguity resolution with inertial attitude augmentation.

The Inertial Attitude Augmentation for Ambiguity Resolution in SF/SE-GNSS Attitude Determination

PubMed Central

Zhu, Jiancheng; Hu, Xiaoping; Zhang, Jingyu; Li, Tao; Wang, Jinling; Wu, Meiping

2014-01-01

The Unaided Single Frequency/Single Epoch Global Navigation Satellite System (SF/SE GNSS) model is the most challenging scenario for ambiguity resolution in the GNSS attitude determination application. To improve the performance of SF/SE-GNSS ambiguity resolution without excessive cost, the Micro-Electro-Mechanical System Inertial Measurement Unit (MEMS-IMU) is a proper choice for the auxiliary sensor that carries out the inertial attitude augmentation. Firstly, based on the SF/SE-GNSS compass model, the Inertial Derived Baseline Vector (IDBV) is defined to connect the MEMS-IMU attitude measurement with the SF/SE-GNSS ambiguity search space, and the mechanism of inertial attitude augmentation is revealed from the perspective of geometry. Then, through the quantitative description of model strength by Ambiguity Dilution of Precision (ADOP), two ADOPs are specified for the unaided SF/SE-GNSS compass model and its inertial attitude augmentation counterparts, respectively, and a sufficient condition is proposed for augmenting the SF/SE-GNSS model strength with inertial attitude measurement. Finally, in the framework of an integer aperture estimator with fixed failure rate, the performance of SF/SE-GNSS ambiguity resolution with inertial attitude augmentation is analyzed when the model strength is varying from strong to weak. The simulation results show that, in the SF/SE-GNSS attitude determination application, MEMS-IMU can satisfy the requirements of ambiguity resolution with inertial attitude augmentation. PMID:24971472

Medical student and junior doctors' tolerance of ambiguity: development of a new scale.

PubMed

Hancock, Jason; Roberts, Martin; Monrouxe, Lynn; Mattick, Karen

2015-03-01

The practice of medicine involves inherent ambiguity, arising from limitations of knowledge, diagnostic problems, complexities of treatment and outcome and unpredictability of patient response. Research into doctors' tolerance of ambiguity is hampered by poor conceptual clarity and inadequate measurement scales. We aimed to create and pilot a measurement scale for tolerance of ambiguity in medical students and junior doctors that addresses the limitations of existing scales. After defining tolerance of ambiguity, scale items were generated by literature review and expert consultation. Feedback on the draft scale was sought and incorporated. 411 medical students and 75 foundation doctors in Exeter, UK were asked to complete the scale. Psychometric analysis enabled further scale refinement and comparison of scale scores across subgroups. The pilot study achieved a 64% response rate. The final 29 item version of the Tolerance of Ambiguity in Medical Students and Doctors (TAMSAD) scale had good internal reliability (Cronbach's α 0.80). Tolerance of ambiguity was higher in foundation year 2 doctors than first, third and fourth year medical students (-5.23, P = 0.012; -5.98, P = 0.013; -4.62, P = 0.035, for each year group respectively). The TAMSAD scale offers a valid and reliable alternative to existing scales. Further work is required in different settings and in longitudinal studies but this study offers intriguing provisional insights.

Athletes' perceptions of role ambiguity and coaching competency in sport teams: a multilevel analysis.

PubMed

Bosselut, Grégoire; Heuzé, Jean-Philippe; Eys, Mark A; Fontayne, Paul; Sarrazin, Philippe

2012-06-01

The purpose of this study was to examine the relationship between athletes' perceptions of role ambiguity and two theoretically derived dimensions of coaching competency (i.e., game strategy and technique competencies). A total of 243 players from 26 teams representing various interdependent sports completed French versions of the Role Ambiguity Scale and the Coaching Competency Scale. Multilevel analyses supported the existence of relationships between the four dimensions of role ambiguity and the two dimensions of coaching competency at both individual and team levels. When the levels were considered jointly, athletes perceiving greater ambiguity in their role in both offensive and defensive contexts were more critical of their coach's capacities to lead their team during competitions and to diagnose or formulate instructions during training sessions. The results also indicated that the dimension of scope of responsibilities was the main contributor to the relationship with coaching competency at an individual level, whereas role evaluation was the main contributor to this relationship at a group level. Findings are discussed in relation to the role episode model, the role ambiguity dimensions involved in the relationships according to the level of analysis considered, and the salience of ambiguity perceptions in the offensive context.

Consequences of Team Job Demands: Role Ambiguity Climate, Affective Engagement, and Extra-Role Performance

PubMed Central

Mañas, Miguel A.; Díaz-Fúnez, Pedro; Pecino, Vicente; López-Liria, Remedios; Padilla, David; Aguilar-Parra, José M.

2018-01-01

In the absence of clearly established procedures in the workplace, employees will experience a negative affective state. This situation influences their well-being and their intention to behave in ways that benefit the organization beyond their job demands. This impact is more relevant on teamwork where members share the perception of ambiguity through emotional contagion (role ambiguity climate). In the framework of the job demands-resources model, the present study analyzes how high levels of role ambiguity climate can have such an effect to reduce employee affective engagement. Over time it has been associated with negative results for the organization due to a lack of extra-role performance. The sample included 706 employees from a multinational company, who were divided into 11 work teams. In line with the formulated hypotheses, the results confirm the negative influence of the role ambiguity climate on extra-role performance, and the mediated effect of affective engagement in the relationship between the role ambiguity climate and extra-role performance. These findings indicate that the role ambiguity climate is related to the adequate or inadequate functioning of employees within a work context. PMID:29375424

Consequences of Team Job Demands: Role Ambiguity Climate, Affective Engagement, and Extra-Role Performance.

PubMed

Mañas, Miguel A; Díaz-Fúnez, Pedro; Pecino, Vicente; López-Liria, Remedios; Padilla, David; Aguilar-Parra, José M

2017-01-01

In the absence of clearly established procedures in the workplace, employees will experience a negative affective state. This situation influences their well-being and their intention to behave in ways that benefit the organization beyond their job demands. This impact is more relevant on teamwork where members share the perception of ambiguity through emotional contagion (role ambiguity climate). In the framework of the job demands-resources model, the present study analyzes how high levels of role ambiguity climate can have such an effect to reduce employee affective engagement. Over time it has been associated with negative results for the organization due to a lack of extra-role performance. The sample included 706 employees from a multinational company, who were divided into 11 work teams. In line with the formulated hypotheses, the results confirm the negative influence of the role ambiguity climate on extra-role performance, and the mediated effect of affective engagement in the relationship between the role ambiguity climate and extra-role performance. These findings indicate that the role ambiguity climate is related to the adequate or inadequate functioning of employees within a work context.

Evaluation of ambiguous associations in the amygdala by learning the structure of the environment.

PubMed

Madarasz, Tamas J; Diaz-Mataix, Lorenzo; Akhand, Omar; Ycu, Edgar A; LeDoux, Joseph E; Johansen, Joshua P

2016-07-01

Recognizing predictive relationships is critical for survival, but an understanding of the underlying neural mechanisms remains elusive. In particular, it is unclear how the brain distinguishes predictive relationships from spurious ones when evidence about a relationship is ambiguous, or how it computes predictions given such uncertainty. To better understand this process, we introduced ambiguity into an associative learning task by presenting aversive outcomes both in the presence and in the absence of a predictive cue. Electrophysiological and optogenetic approaches revealed that amygdala neurons directly regulated and tracked the effects of ambiguity on learning. Contrary to established accounts of associative learning, however, interference from competing associations was not required to assess an ambiguous cue-outcome contingency. Instead, animals' behavior was explained by a normative account that evaluates different models of the environment's statistical structure. These findings suggest an alternative view of amygdala circuits in resolving ambiguity during aversive learning.

Measuring the ambiguity tolerance of medical students: a cross-sectional study from the first to sixth academic years

PubMed Central

2014-01-01

Background Tolerance of ambiguity, or the extent to which ambiguous situations are perceived as desirable, is an important component of the attitudes and behaviors of medical students. However, few studies have compared this trait across the years of medical school. General practitioners are considered to have a higher ambiguity tolerance than specialists. We compared ambiguity tolerance between general practitioners and medical students. Methods We designed a cross-sectional study to evaluate the ambiguity tolerance of 622 medical students in the first to sixth academic years. We compared this with the ambiguity tolerance of 30 general practitioners. We used the inventory for measuring ambiguity tolerance (IMA) developed by Reis (1997), which includes three measures of ambiguity tolerance: openness to new experiences, social conflicts, and perception of insoluble problems. Results We obtained a total of 564 complete data sets (return rate 90.1%) from medical students and 29 questionnaires (return rate 96.7%) from general practitioners. In relation to the reference groups defined by Reis (1997), medical students had poor ambiguity tolerance on all three scales. No differences were found between those in the first and the sixth academic years, although we did observe gender-specific differences in ambiguity tolerance. We found no differences in ambiguity tolerance between general practitioners and medical students. Conclusions The ambiguity tolerance of the students that we assessed was below average, and appeared to be stable throughout the course of their studies. In contrast to our expectations, the general practitioners did not have a higher level of ambiguity tolerance than the students did. PMID:24405525

Measuring the ambiguity tolerance of medical students: a cross-sectional study from the first to sixth academic years.

PubMed

Weissenstein, Anne; Ligges, Sandra; Brouwer, Britta; Marschall, Bernhard; Friederichs, Hendrik

2014-01-09

Tolerance of ambiguity, or the extent to which ambiguous situations are perceived as desirable, is an important component of the attitudes and behaviors of medical students. However, few studies have compared this trait across the years of medical school. General practitioners are considered to have a higher ambiguity tolerance than specialists. We compared ambiguity tolerance between general practitioners and medical students. We designed a cross-sectional study to evaluate the ambiguity tolerance of 622 medical students in the first to sixth academic years. We compared this with the ambiguity tolerance of 30 general practitioners. We used the inventory for measuring ambiguity tolerance (IMA) developed by Reis (1997), which includes three measures of ambiguity tolerance: openness to new experiences, social conflicts, and perception of insoluble problems. We obtained a total of 564 complete data sets (return rate 90.1%) from medical students and 29 questionnaires (return rate 96.7%) from general practitioners. In relation to the reference groups defined by Reis (1997), medical students had poor ambiguity tolerance on all three scales. No differences were found between those in the first and the sixth academic years, although we did observe gender-specific differences in ambiguity tolerance. We found no differences in ambiguity tolerance between general practitioners and medical students. The ambiguity tolerance of the students that we assessed was below average, and appeared to be stable throughout the course of their studies. In contrast to our expectations, the general practitioners did not have a higher level of ambiguity tolerance than the students did.

Ambiguous Belonging and the Challenge of Inclusion: Parent Perspectives on School Membership

ERIC Educational Resources Information Center

Scorgie, Kate

2015-01-01

Boundary ambiguity occurs when members of a family are confused or uncertain regarding roles, responsibilities and subsystem configurations within the family. Research suggests that perception of boundary ambiguity is associated with family stress despite internal and external resource availability. It has been suggested that research on family…

The Relationship between Tolerance of Ambiguity and Stereotyping: Implications for BSW Education

ERIC Educational Resources Information Center

Valutis, Stephanie A.

2015-01-01

Ambiguity tolerance and intolerance can influence one's professional practice. The study of such influences remains sparse within the social work literature. Behaviors that reduce uncertainty, including categorizing or stereotyping, are used by those who feel discomfort in ambiguous situations. This study explores explore the relationship between…

A Multiple-Channel Model of Task-Dependent Ambiguity Resolution in Sentence Comprehension

ERIC Educational Resources Information Center

Logacev, Pavel; Vasishth, Shravan

2016-01-01

Traxler, Pickering, and Clifton (1998) found that ambiguous sentences are read faster than their unambiguous counterparts. This so-called "ambiguity advantage" has presented a major challenge to classical theories of human sentence comprehension (parsing) because its most prominent explanation, in the form of the unrestricted race model…

REDUCING AMBIGUITY IN THE FUNCTIONAL ASSESSMENT OF PROBLEM BEHAVIOR

PubMed Central

Rooker, Griffin W.; DeLeon, Iser G.; Borrero, Carrie S. W.; Frank-Crawford, Michelle A.; Roscoe, Eileen M.

2015-01-01

Severe problem behavior (e.g., self-injury and aggression) remains among the most serious challenges for the habilitation of persons with intellectual disabilities and is a significant obstacle to community integration. The current standard of behavior analytic treatment for problem behavior in this population consists of a functional assessment and treatment model. Within that model, the first step is to assess the behavior–environment relations that give rise to and maintain problem behavior, a functional behavioral assessment. Conventional methods of assessing behavioral function include indirect, descriptive, and experimental assessments of problem behavior. Clinical investigators have produced a rich literature demonstrating the relative effectiveness for each method, but in clinical practice, each can produce ambiguous or difficult-to-interpret outcomes that may impede treatment development. This paper outlines potential sources of variability in assessment outcomes and then reviews the evidence on strategies for avoiding ambiguous outcomes and/or clarifying initially ambiguous results. The end result for each assessment method is a set of best practice guidelines, given the available evidence, for conducting the initial assessment. PMID:26236145

Acute stress affects risk taking but not ambiguity aversion.

PubMed

Buckert, Magdalena; Schwieren, Christiane; Kudielka, Brigitte M; Fiebach, Christian J

2014-01-01

Economic decisions are often made in stressful situations (e.g., at the trading floor), but the effects of stress on economic decision making have not been systematically investigated so far. The present study examines how acute stress influences economic decision making under uncertainty (risk and ambiguity) using financially incentivized lotteries. We varied the domain of decision making as well as the expected value of the risky prospect. Importantly, no feedback was provided to investigate risk taking and ambiguity aversion independent from learning processes. In a sample of 75 healthy young participants, 55 of whom underwent a stress induction protocol (Trier Social Stress Test for Groups), we observed more risk seeking for gains. This effect was restricted to a subgroup of participants that showed a robust cortisol response to acute stress (n = 26). Gambling under ambiguity, in contrast to gambling under risk, was not influenced by the cortisol response to stress. These results show that acute psychosocial stress affects economic decision making under risk, independent of learning processes. Our results further point to the importance of cortisol as a mediator of this effect.

Perceptions of boundary ambiguity in the process of leaving an abusive partner.

PubMed

Khaw, Lyndal; Hardesty, Jennifer L

2015-06-01

The process of leaving an abusive partner has been theorized using the Stages of Change Model. Although useful, this model does not account for changes in relational boundaries unique to the process of leaving. Using family stress and feminist perspectives, this study sought to integrate boundary ambiguity into the Stages of Change Model. Boundary ambiguity is defined as a perception of uncertainty as to who is in or out of a family system (Boss & Greenberg, 1984). Twenty-five mothers who had temporarily or permanently left their abusers were interviewed. Data were analyzed using constructivist grounded theory methods. Results identify types, indicators of, and mothers' responses to boundary ambiguity throughout the five stages of change. Most mothers and abusers fluctuated between physical and psychological presence and absence over multiple separations. The integration of boundary ambiguity into the Stages of Change Model highlights the process of leaving an abusive partner as systemic, fluid, and nonlinear. © 2014 Family Process Institute.

Impressions of people with gender-ambiguous male or female first names.

PubMed

McKelvie, Stuart J; Waterhouse, Kelly

2005-10-01

Undergraduates (12 men, 12 women) read a scenario in which they formed an impression of nine people who had left their first name on an answering machine. Participants rated the extent to which seven characteristics (Ethical, Caring, Popular, Cheerful, Successful, Masculine, Feminine) applied to people whose first names were gender-ambiguous (e.g., Chris), male (e.g., Ken) or female (e.g., Pam). People with gender-ambiguous names were rated less Ethical than those with female names, and people with gender-ambiguous names and male names were rated less Caring, less Cheerful, and less Feminine than those with female names. These results are consistent with the idea that there is a bias towards assuming that a person of unspecified sex is a male.

Authoritarianism, cognitive rigidity, and the processing of ambiguous visual information.

PubMed

Duncan, Lauren E; Peterson, Bill E

2014-01-01

Intolerance of ambiguity and cognitive rigidity are unifying aspects of authoritarianism as defined by Adorno, Frenkel-Brunswik, Levinson, and Sanford (1982/1950), who hypothesized that authoritarians view the world in absolute terms (e.g., good or evil). Past studies have documented the relationship between authoritarianism and intolerance of ambiguity and rigidity. Frenkel-Brunswik (1949) hypothesized that this desire for absolutism was rooted in perceptual processes. We present a study with three samples that directly tests the relationship between right wing authoritarianism (RWA) and the processing of ideologically neutral but ambiguous visual stimuli. As hypothesized, in all three samples we found that RWA was related to the slower processing of visual information that required participants to recategorize objects. In a fourth sample, RWA was unrelated to speed of processing visual information that did not require recategorization. Overall, results suggest a relationship between RWA and rigidity in categorization.

Ambiguity assessment of small-angle scattering curves from monodisperse systems.

PubMed

Petoukhov, Maxim V; Svergun, Dmitri I

2015-05-01

A novel approach is presented for an a priori assessment of the ambiguity associated with spherically averaged single-particle scattering. The approach is of broad interest to the structural biology community, allowing the rapid and model-independent assessment of the inherent non-uniqueness of three-dimensional shape reconstruction from scattering experiments on solutions of biological macromolecules. One-dimensional scattering curves recorded from monodisperse systems are nowadays routinely utilized to generate low-resolution particle shapes, but the potential ambiguity of such reconstructions remains a major issue. At present, the (non)uniqueness can only be assessed by a posteriori comparison and averaging of repetitive Monte Carlo-based shape-determination runs. The new a priori ambiguity measure is based on the number of distinct shape categories compatible with a given data set. For this purpose, a comprehensive library of over 14,000 shape topologies has been generated containing up to seven beads closely packed on a hexagonal grid. The computed scattering curves rescaled to keep only the shape topology rather than the overall size information provide a `scattering map' of this set of shapes. For a given scattering data set, one rapidly obtains the number of neighbours in the map and the associated shape topologies such that in addition to providing a quantitative ambiguity measure the algorithm may also serve as an alternative shape-analysis tool. The approach has been validated in model calculations on geometrical bodies and its usefulness is further demonstrated on a number of experimental X-ray scattering data sets from proteins in solution. A quantitative ambiguity score (a-score) is introduced to provide immediate and convenient guidance to the user on the uniqueness of the ab initio shape reconstruction from the given data set.

Phase-ambiguity resolution for QPSK modulation systems. Part 2: A method to resolve offset QPSK

NASA Technical Reports Server (NTRS)

Nguyen, Tien Manh

1989-01-01

Part 2 presents a new method to resolve the phase-ambiguity for Offset QPSK modulation systems. When an Offset Quaternary Phase-Shift-Keyed (OQPSK) communications link is utilized, the phase ambiguity of the reference carrier must be resolved. At the transmitter, two different unique words are separately modulated onto the quadrature carriers. At the receiver, the recovered carrier may have one of four possible phases, 0, 90, 180, or 270 degrees, referenced to the nominally correct phase. The IF portion of the channel may cause a phase-sense reversal, i.e., a reversal in the direction of phase rotation for a specified bit pattern. Hence, eight possible phase relationships (the so-called eight ambiguous phase conditions) between input and output of the demodulator must be resolved. Using the In-phase (I)/Quadrature (Q) channel reversal correcting property of an OQPSK Costas loop with integrated symbol synchronization, four ambiguous phase conditions are eliminated. Thus, only four possible ambiguous phase conditions remain. The errors caused by the remaining ambiguous phase conditions can be corrected by monitoring and detecting the polarity of the two unique words. The correction of the unique word polarities results in the complete phase-ambiguity resolution for the OQPSK system.

Three-frequency BDS precise point positioning ambiguity resolution based on raw observables

NASA Astrophysics Data System (ADS)

Li, Pan; Zhang, Xiaohong; Ge, Maorong; Schuh, Harald

2018-02-01

All BeiDou navigation satellite system (BDS) satellites are transmitting signals on three frequencies, which brings new opportunity and challenges for high-accuracy precise point positioning (PPP) with ambiguity resolution (AR). This paper proposes an effective uncalibrated phase delay (UPD) estimation and AR strategy which is based on a raw PPP model. First, triple-frequency raw PPP models are developed. The observation model and stochastic model are designed and extended to accommodate the third frequency. Then, the UPD is parameterized in raw frequency form while estimating with the high-precision and low-noise integer linear combination of float ambiguity which are derived by ambiguity decorrelation. Third, with UPD corrected, the LAMBDA method is used for resolving full or partial ambiguities which can be fixed. This method can be easily and flexibly extended for dual-, triple- or even more frequency. To verify the effectiveness and performance of triple-frequency PPP AR, tests with real BDS data from 90 stations lasting for 21 days were performed in static mode. Data were processed with three strategies: BDS triple-frequency ambiguity-float PPP, BDS triple-frequency PPP with dual-frequency (B1/B2) and three-frequency AR, respectively. Numerous experiment results showed that compared with the ambiguity-float solution, the performance in terms of convergence time and positioning biases can be significantly improved by AR. Among three groups of solutions, the triple-frequency PPP AR achieved the best performance. Compared with dual-frequency AR, additional the third frequency could apparently improve the position estimations during the initialization phase and under constraint environments when the dual-frequency PPP AR is limited by few satellite numbers.

Evaluation of ambiguous associations in the amygdala by learning the structure of the environment

PubMed Central

Madarasz, Tamas J.; Diaz-Mataix, Lorenzo; Akhand, Omar; Ycu, Edgar A.; LeDoux, Joseph E.; Johansen, Joshua P.

2017-01-01

Recognizing predictive relationships is critical for survival, but an understanding of the underlying neural mechanisms remains elusive. In particular it is unclear how the brain distinguishes predictive relationships from spurious ones when evidence about a relationship is ambiguous, or how it computes predictions given such uncertainty. To better understand this process we introduced ambiguity into an associative learning task by presenting aversive outcomes both in the presence and absence of a predictive cue. Electrophysiological and optogenetic approaches revealed that amygdala neurons directly regulate and track the effects of ambiguity on learning. Contrary to established accounts of associative learning however, interference from competing associations was not required to assess an ambiguous cue-outcome contingency. Instead, animals’ behavior was explained by a normative account that evaluates different models of the environment’s statistical structure. These findings suggest an alternative view on the role of amygdala circuits in resolving ambiguity during aversive learning. PMID:27214568

Critical Thinking: Attitudes, Skills, and Ambiguity.

ERIC Educational Resources Information Center

Shaughnessy, Michael F.

This paper provides an overview of the realm of critical thinking. The document explores the development of a critical thinking attitude and specific skills relative to logic, rationality, and reasoning that must be fostered to facilitate and enhance future learning. The issue of ambiguity also is addressed as a central construct of the critical…

Does language ambiguity in clinical practice justify the introduction of standard terminology? An integrative review.

PubMed

Stallinga, Hillegonda A; ten Napel, Huib; Jansen, Gerard J; Geertzen, Jan H B; de Vries Robbé, Pieter F; Roodbol, Petrie F

2015-02-01

To research the use of ambiguous language in written information concerning patients' functioning and to identify problems resulting from the use of ambiguous language in clinical practice. Many projects that aimed to introduce standard terminology concerning patients' functioning in clinical practice are unsuccessful because standard terminology is rarely used in clinical practice. These projects mainly aim to improve communication by reducing ambiguous language. Considering their lack of success, the validity of the argument that language ambiguity is used in clinical practice is questioned. An integrative literature review. A systematic search of the MEDLINE (1950-2012) and CINAHL (1982-2012) databases was undertaken, including empirical and theoretical literature. The selected studies were critically appraised using a data assessment and extraction form. Seventeen of 767 papers were included in the review and synthesis. The use of ambiguous language in written information concerning patients' functioning was demonstrated. Problems resulting from the use of ambiguous language in clinical practice were not identified. However, several potential problems were suggested, including hindered clinical decision-making and limited research opportunities. The results of this review demonstrated the use of ambiguous language concerning patients' functioning, but health professionals in clinical practice did not experience this issue as a problem. This finding might explain why many projects aimed at introducing standard terminology concerning functioning in clinical practice to solve problems caused by ambiguous language are often unsuccessful. Language ambiguity alone is not a valid argument to justify the introduction of standard terminology. The introduction of standard terminology concerning patients' functioning will only be successful when clinical practice requires the aggregation and reuse of data from electronic patient records for different purposes, including

The interaction of patient race, provider bias, and clinical ambiguity on pain management decisions

PubMed Central

Hirsh, Adam T.; Hollingshead, Nicole A.; Ashburn-Nardo, Leslie; Kroenke, Kurt

2015-01-01

Although racial disparities in pain care are widely reported, much remains to be known about the role of provider and contextual factors. We used computer-simulated patients to examine the influence of patient race, provider racial bias, and clinical ambiguity on pain decisions. One hundred twenty nine medical residents/fellows made assessment (pain intensity) and treatment (opioid and non-opioid analgesics) decisions for 12 virtual patients with acute pain. Race (Black/White) and clinical ambiguity (high/low) were manipulated across vignettes. Participants completed the Implicit Association Test and feeling thermometers, which assess implicit and explicit racial biases, respectively. Individual- and group-level analyses indicated that race and ambiguity had an interactive effect on providers’ decisions, such that decisions varied as a function of ambiguity for White but not Black patients. Individual differences across providers were observed for the effect of race and ambiguity on decisions; however providers’ implicit and explicit biases did not account for this variability. These data highlight the complexity of racial disparities and suggest that differences in care between White and Black patients are, in part, attributable to the nature (i.e., ambiguity) of the clinical scenario. The current study suggests that interventions to reduce disparities should differentially target patient, provider, and contextual factors. PMID:25828370

Mid-Cretaceous carbon cycle perturbations and Oceanic Anoxic Events recorded in southern Tibet

NASA Astrophysics Data System (ADS)

Zhang, Xiaolin; Chen, Kefan; Hu, Dongping; Sha, Jingeng

2016-12-01

The organic carbon isotope (δ13Corg) curve for ~1.7-km-thick mid-Cretaceous strata of the Chaqiela section in Gamba area, southern Tibet is presented in this study. C-isotopic chemostratigraphic correlation combined with biostratigraphic constraints show that the Chaqiela section spans early Aptian through early Campanian period, and that almost all of the carbon cycle perturbations and Oceanic Anoxic Events during the mid-Cretaceous period are well recorded in the continental margin area of the southeastern Tethys Ocean. Significantly, two levels of methane-derived authigenic carbonates were identified at the onset of OAE1b near the Aptian-Albian boundary. We suggest that an increase in methane release from gas hydrates, potentially driven by sea-level fall and bottom water temperature increase, may have contributed to the large negative δ13Corg excursions and global warming during OAE1b.

Automated ambiguity estimation for VLBI Intensive sessions using L1-norm

NASA Astrophysics Data System (ADS)

Kareinen, Niko; Hobiger, Thomas; Haas, Rüdiger

2016-12-01

Very Long Baseline Interferometry (VLBI) is a space-geodetic technique that is uniquely capable of direct observation of the angle of the Earth's rotation about the Celestial Intermediate Pole (CIP) axis, namely UT1. The daily estimates of the difference between UT1 and Coordinated Universal Time (UTC) provided by the 1-h long VLBI Intensive sessions are essential in providing timely UT1 estimates for satellite navigation systems and orbit determination. In order to produce timely UT1 estimates, efforts have been made to completely automate the analysis of VLBI Intensive sessions. This involves the automatic processing of X- and S-band group delays. These data contain an unknown number of integer ambiguities in the observed group delays. They are introduced as a side-effect of the bandwidth synthesis technique, which is used to combine correlator results from the narrow channels that span the individual bands. In an automated analysis with the c5++ software the standard approach in resolving the ambiguities is to perform a simplified parameter estimation using a least-squares adjustment (L2-norm minimisation). We implement L1-norm as an alternative estimation method in c5++. The implemented method is used to automatically estimate the ambiguities in VLBI Intensive sessions on the Kokee-Wettzell baseline. The results are compared to an analysis set-up where the ambiguity estimation is computed using the L2-norm. For both methods three different weighting strategies for the ambiguity estimation are assessed. The results show that the L1-norm is better at automatically resolving the ambiguities than the L2-norm. The use of the L1-norm leads to a significantly higher number of good quality UT1-UTC estimates with each of the three weighting strategies. The increase in the number of sessions is approximately 5% for each weighting strategy. This is accompanied by smaller post-fit residuals in the final UT1-UTC estimation step.

Resolving Phase Ambiguities In OQPSK

NASA Technical Reports Server (NTRS)

Nguyen, Tien M.

1991-01-01

Improved design for modulator and demodulator in offset-quaternary-phase-key-shifting (OQPSK) communication system enables receiver to resolve ambiguity in estimated phase of received signal. Features include unique-code-word modulation and detection and digital implementation of Costas loop in carrier-recovery subsystem. Enchances performance of carrier-recovery subsystem, reduces complexity of receiver by removing redundant circuits from previous design, and eliminates dependence of timing in receiver upon parallel-to-serial-conversion clock.

On the Impact of L2 Speech Rhythm on Syntactic Ambiguity Resolution

ERIC Educational Resources Information Center

Roncaglia-Denissen, M. Paula; Schmidt-Kassow, Maren; Heine, Angela; Kotz, Sonja A.

2015-01-01

In an event-related potential (ERP) study we investigated the role of age of acquisition (AoA) on the use of second language rhythmic properties during syntactic ambiguity resolution. Syntactically ambiguous sentences embedded in rhythmically regular and irregular contexts were presented to Turkish early and late second language (L2) learners of…

Transfer in L3 Sentence Processing: Evidence from Relative Clause Attachment Ambiguities

ERIC Educational Resources Information Center

Rah, Anne

2010-01-01

The present study investigates transfer effects in two groups of German learners of French for ambiguous relative clause (RC) constructions. The first learner group had started to learn French before English, whereas the second group had started to learn English before French. The RC attachment ambiguity is interesting to study possible transfer…

The Ethics of Ambiguity: Rethinking the Role and Importance of Uncertainty in Medical Education and Practice.

PubMed

Domen, Ronald E

2016-01-01

Understanding and embracing uncertainty are critical for effective teacher-learner relationships as well as for shared decision-making in the physician-patient relationship. However, ambiguity has not been given serious consideration in either the undergraduate or graduate medical curricula or in the role it plays in patient-centered care. In this article, the author examines the ethics of ambiguity and argues for a pedagogy that includes education in the importance of, and tolerance of, ambiguity that is inherent in medical education and practice. Common threads running through the ethics of ambiguity are the virtue of respect, and the development of a culture of respect is required for the successful understanding and implementation of a pedagogy of ambiguity.

The interaction of patient race, provider bias, and clinical ambiguity on pain management decisions.

PubMed

Hirsh, Adam T; Hollingshead, Nicole A; Ashburn-Nardo, Leslie; Kroenke, Kurt

2015-06-01

Although racial disparities in pain care are widely reported, much remains to be known about the role of provider and contextual factors. We used computer-simulated patients to examine the influence of patient race, provider racial bias, and clinical ambiguity on pain decisions. One hundred twenty-nine medical residents/fellows made assessment (pain intensity) and treatment (opioid and nonopioid analgesics) decisions for 12 virtual patients with acute pain. Race (black/white) and clinical ambiguity (high/low) were manipulated across vignettes. Participants completed the Implicit Association Test and feeling thermometers, which assess implicit and explicit racial biases, respectively. Individual- and group-level analyses indicated that race and ambiguity had an interactive effect on providers' decisions, such that decisions varied as a function of ambiguity for white but not for black patients. Individual differences across providers were observed for the effect of race and ambiguity on decisions; however, providers' implicit and explicit biases did not account for this variability. These data highlight the complexity of racial disparities and suggest that differences in care between white and black patients are, in part, attributable to the nature (ie, ambiguity) of the clinical scenario. The current study suggests that interventions to reduce disparities should differentially target patient, provider, and contextual factors. This study examined the unique and collective influence of patient race, provider racial bias, and clinical ambiguity on providers' pain management decisions. These results could inform the development of interventions aimed at reducing disparities and improving pain care. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

Emotion and Decision-Making Under Uncertainty: Physiological arousal predicts increased gambling during ambiguity but not risk

PubMed Central

FeldmanHall, Oriel; Glimcher, Paul; Baker, Augustus L; Phelps, Elizabeth A

2016-01-01

Uncertainty, which is ubiquitous in decision-making, can be fractionated into known probabilities (risk) and unknown probabilities (ambiguity). Although research illustrates that individuals more often avoid decisions associated with ambiguity compared to risk, it remains unclear why ambiguity is perceived as more aversive. Here we examine the role of arousal in shaping the representation of value and subsequent choice under risky and ambiguous decisions. To investigate the relationship between arousal and decisions of uncertainty, we measure skin conductance response—a quantifiable measure reflecting sympathetic nervous system arousal—during choices to gamble under risk and ambiguity. To quantify the discrete influences of risk and ambiguity sensitivity and the subjective value of each option under consideration, we model fluctuating uncertainty, as well as the amount of money that can be gained by taking the gamble. Results reveal that while arousal tracks the subjective value of a lottery regardless of uncertainty type, arousal differentially contributes to the computation of value—i.e. choice—depending on whether the uncertainty is risky or ambiguous: enhanced arousal adaptively decreases risk-taking only when the lottery is highly risky but increases risk-taking when the probability of winning is ambiguous (even after controlling for subjective value). Together, this suggests that the role of arousal during decisions of uncertainty is modulatory and highly dependent on the context in which the decision is framed. PMID:27690508

Turning an advantage into a disadvantage: ambiguity effects in lexical decision versus reading tasks.

PubMed

Piercey, C D; Joordens, S

2000-06-01

When performing a lexical decision task, participants can correctly categorize letter strings as words faster if they have multiple meanings (i.e., ambiguous words) than if they have one meaning (i.e., unambiguous words). In contrast, when reading connected text, participants tend to fixate longer on ambiguous words than on unambiguous words. Why are ambiguous words at an advantage in one word recognition task, and at a disadvantage in another? These disparate results can be reconciled if it is assumed that ambiguous words are relatively fast to reach a semantic-blend state sufficient for supporting lexical decisions, but then slow to escape the blend when the task requires a specific meaning be retrieved. We report several experiments that support this possibility.

Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference

PubMed Central

Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

2017-01-01

Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation. PMID:28468257

Acute stress affects risk taking but not ambiguity aversion

PubMed Central

Buckert, Magdalena; Schwieren, Christiane; Kudielka, Brigitte M.; Fiebach, Christian J.

2014-01-01

Economic decisions are often made in stressful situations (e.g., at the trading floor), but the effects of stress on economic decision making have not been systematically investigated so far. The present study examines how acute stress influences economic decision making under uncertainty (risk and ambiguity) using financially incentivized lotteries. We varied the domain of decision making as well as the expected value of the risky prospect. Importantly, no feedback was provided to investigate risk taking and ambiguity aversion independent from learning processes. In a sample of 75 healthy young participants, 55 of whom underwent a stress induction protocol (Trier Social Stress Test for Groups), we observed more risk seeking for gains. This effect was restricted to a subgroup of participants that showed a robust cortisol response to acute stress (n = 26). Gambling under ambiguity, in contrast to gambling under risk, was not influenced by the cortisol response to stress. These results show that acute psychosocial stress affects economic decision making under risk, independent of learning processes. Our results further point to the importance of cortisol as a mediator of this effect. PMID:24834024

Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference.

PubMed

Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

2017-04-29

Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation.

Organic geochemistry of the early Toarcian oceanic anoxic event in Hawsker Bottoms, Yorkshire, England

NASA Astrophysics Data System (ADS)

French, K. L.; Sepúlveda, J.; Trabucho-Alexandre, J.; Gröcke, D. R.; Summons, R. E.

2014-03-01

A comprehensive organic geochemical investigation of the Hawsker Bottoms outcrop section in Yorkshire, England has provided new insights about environmental conditions leading into and during the Toarcian oceanic anoxic event (T-OAE; ∼183 Ma). Rock-Eval and molecular analyses demonstrate that the section is uniformly within the early oil window. Hydrogen index (HI), organic petrography, polycyclic aromatic hydrocarbon (PAH) distributions, and tricyclic terpane ratios mark a shift to a lower relative abundance of terrigenous organic matter supplied to the sampling locality during the onset of the T-OAE and across a lithological transition. Unlike other ancient intervals of anoxia and extinction, biomarker indices of planktonic community structure do not display major changes or anomalous values. Depositional environment and redox indicators support a shift towards more reducing conditions in the sediment porewaters and the development of a seasonally stratified water column during the T-OAE. In addition to carotenoid biomarkers for green sulfur bacteria (GSB), we report the first occurrence of okenane, a marker of purple sulfur bacteria (PSB), in marine samples younger than ∼1.64 Ga. Based on modern observations, a planktonic source of okenane's precursor, okenone, would require extremely shallow photic zone euxinia (PZE) and a highly restricted depositional environment. However, due to coastal vertical mixing, the lack of planktonic okenone production in modern marine sulfidic environments, and building evidence of okenone production in mat-dwelling Chromatiaceae, we propose a sedimentary source of okenone as an alternative. Lastly, we report the first parallel compound-specific δC13 record in marine- and terrestrial-derived biomarkers across the T-OAE. The δC13 records of short-chain n-alkanes, acyclic isoprenoids, and long-chain n-alkanes all encode negative carbon isotope excursions (CIEs), and together, they support an injection of isotopically light

Multiple-stage ambiguity in motion perception reveals global computation of local motion directions.

PubMed

Rider, Andrew T; Nishida, Shin'ya; Johnston, Alan

2016-12-01

The motion of a 1D image feature, such as a line, seen through a small aperture, or the small receptive field of a neural motion sensor, is underconstrained, and it is not possible to derive the true motion direction from a single local measurement. This is referred to as the aperture problem. How the visual system solves the aperture problem is a fundamental question in visual motion research. In the estimation of motion vectors through integration of ambiguous local motion measurements at different positions, conventional theories assume that the object motion is a rigid translation, with motion signals sharing a common motion vector within the spatial region over which the aperture problem is solved. However, this strategy fails for global rotation. Here we show that the human visual system can estimate global rotation directly through spatial pooling of locally ambiguous measurements, without an intervening step that computes local motion vectors. We designed a novel ambiguous global flow stimulus, which is globally as well as locally ambiguous. The global ambiguity implies that the stimulus is simultaneously consistent with both a global rigid translation and an infinite number of global rigid rotations. By the standard view, the motion should always be seen as a global translation, but it appears to shift from translation to rotation as observers shift fixation. This finding indicates that the visual system can estimate local vectors using a global rotation constraint, and suggests that local motion ambiguity may not be resolved until consistencies with multiple global motion patterns are assessed.

Recognition and assessment of atypical and ambiguous genitalia in the newborn.

PubMed

Davies, Justin H; Cheetham, Timothy

2017-10-01

The baby with atypical or ambiguous genitalia is usually born in secondary care. For most clinicians, this is an unfamiliar and challenging scenario with the potential for life-long ramifications arising from a consultation led by an unprepared clinician. Language needs to be used carefully with particular clarity when liaising with parents, local health professionals and the specialist multidisciplinary team. Confidence in the recognition and assessment of atypical or ambiguous genitalia in a newborn will guide the local clinician when deciding on the initial investigations required and is a foundation for subsequent management. The local team have key roles in the initial support for parents as well as managing expectations at a time of great uncertainty. There are numerous different diagnoses that can result in atypical or ambiguous genitalia. The clinical findings should guide the initial investigations, and there are many pitfalls when it comes to interpreting the results. The aim of this article is to provide an initial approach to the management of a baby born with atypical or ambiguous genitalia. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Tracing Carbon Cycling in the Atmosphere and Oceans During the Cretaceous Ocean Anoxic Event 2 (OAE2, 94Ma)

NASA Astrophysics Data System (ADS)

Moran, S. A. M.; Boudinot, F. G.; Dildar, N.; Sepúlveda, J.

2017-12-01

We present a high-resolution record of compound-specific stable carbon isotope data from short-chain—aquatic algae—and long-chain n-alkanes—terrestrial plants—preserved in sedimentary sequences from the Smokey Hollow #1 (SH1) core in the Grand Staircase Escalante National Monument in southern Utah. The study area covered by SH1 core was situated at the western margin of the Western Interior Seaway during the Cretaceous Ocean Anoxic Event (OAE2, 94Ma.), and was characterized by high sedimentation rates and enhanced preservation of both marine and terrestrial organic matter. Short- and long-chain n-alkanes were isolated and purified from branched and cyclic aliphatic hydrocarbons using an optimized urea adduction protocol, and δ13Cn-alkane was measured using a Thermo MAT253 GC-C-IR-MS. We use the δ13Cn-alkane from aquatic and terrestrial sources to better understand carbon cycle interactions in the oceanic and atmospheric carbon pools across this event. Our results indicate that the δ13C of terrestrial plants experienced a faster and more pronounced positive carbon isotope excursion compared to marine sources. We will discuss how these results can inform models of carbon cycle interactions between the ocean and the atmosphere during greenhouse climates, and how they can be used to trace possible sources of CO2.

The Kindergarten Path Effect Revisited: Children's Use of Context in Processing Structural Ambiguities

ERIC Educational Resources Information Center

Weighall, Anna R.

2008-01-01

Research with adults has shown that ambiguous spoken sentences are resolved efficiently, exploiting multiple cues--including referential context--to select the intended meaning. Paradoxically, children appear to be insensitive to referential cues when resolving ambiguous sentences, relying instead on statistical properties intrinsic to the…

Making Decisions under Ambiguity: Judgment Bias Tasks for Assessing Emotional State in Animals

PubMed Central

Roelofs, Sanne; Boleij, Hetty; Nordquist, Rebecca E.; van der Staay, Franz Josef

2016-01-01

Judgment bias tasks (JBTs) are considered as a family of promising tools in the assessment of emotional states of animals. JBTs provide a cognitive measure of optimism and/or pessimism by recording behavioral responses to ambiguous stimuli. For instance, a negative emotional state is expected to produce a negative or pessimistic judgment of an ambiguous stimulus, whereas a positive emotional state produces a positive or optimistic judgment of the same ambiguous stimulus. Measuring an animal’s emotional state or mood is relevant in both animal welfare research and biomedical research. This is reflected in the increasing use of JBTs in both research areas. We discuss the different implementations of JBTs with animals, with a focus on their potential as an accurate measure of emotional state. JBTs have been successfully applied to a very broad range of species, using many different types of testing equipment and experimental protocols. However, further validation of this test is deemed necessary. For example, the often extensive training period required for successful judgment bias testing remains a possible factor confounding results. Also, the issue of ambiguous stimuli losing their ambiguity with repeated testing requires additional attention. Possible improvements are suggested to further develop the JBTs in both animal welfare and biomedical research. PMID:27375454

Emotion and decision-making under uncertainty: Physiological arousal predicts increased gambling during ambiguity but not risk.

PubMed

FeldmanHall, Oriel; Glimcher, Paul; Baker, Augustus L; Phelps, Elizabeth A

2016-10-01

Uncertainty, which is ubiquitous in decision-making, can be fractionated into known probabilities (risk) and unknown probabilities (ambiguity). Although research has illustrated that individuals more often avoid decisions associated with ambiguity compared to risk, it remains unclear why ambiguity is perceived as more aversive. Here we examine the role of arousal in shaping the representation of value and subsequent choice under risky and ambiguous decisions. To investigate the relationship between arousal and decisions of uncertainty, we measure skin conductance response-a quantifiable measure reflecting sympathetic nervous system arousal-during choices to gamble under risk and ambiguity. To quantify the discrete influences of risk and ambiguity sensitivity and the subjective value of each option under consideration, we model fluctuating uncertainty, as well as the amount of money that can be gained by taking the gamble. Results reveal that although arousal tracks the subjective value of a lottery regardless of uncertainty type, arousal differentially contributes to the computation of value-that is, choice-depending on whether the uncertainty is risky or ambiguous: Enhanced arousal adaptively decreases risk-taking only when the lottery is highly risky but increases risk-taking when the probability of winning is ambiguous (even after controlling for subjective value). Together, this suggests that the role of arousal during decisions of uncertainty is modulatory and highly dependent on the context in which the decision is framed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Rate-gyro-integral constraint for ambiguity resolution in GNSS attitude determination applications.

PubMed

Zhu, Jiancheng; Li, Tao; Wang, Jinling; Hu, Xiaoping; Wu, Meiping

2013-06-21

In the field of Global Navigation Satellite System (GNSS) attitude determination, the constraints usually play a critical role in resolving the unknown ambiguities quickly and correctly. Many constraints such as the baseline length, the geometry of multi-baselines and the horizontal attitude angles have been used extensively to improve the performance of ambiguity resolution. In the GNSS/Inertial Navigation System (INS) integrated attitude determination systems using low grade Inertial Measurement Unit (IMU), the initial heading parameters of the vehicle are usually worked out by the GNSS subsystem instead of by the IMU sensors independently. However, when a rotation occurs, the angle at which vehicle has turned within a short time span can be measured accurately by the IMU. This measurement will be treated as a constraint, namely the rate-gyro-integral constraint, which can aid the GNSS ambiguity resolution. We will use this constraint to filter the candidates in the ambiguity search stage. The ambiguity search space shrinks significantly with this constraint imposed during the rotation, thus it is helpful to speeding up the initialization of attitude parameters under dynamic circumstances. This paper will only study the applications of this new constraint to land vehicles. The impacts of measurement errors on the effect of this new constraint will be assessed for different grades of IMU and current average precision level of GNSS receivers. Simulations and experiments in urban areas have demonstrated the validity and efficacy of the new constraint in aiding GNSS attitude determinations.

Exploring Situated Ambiguity in Students' Entrepreneurial Learning

ERIC Educational Resources Information Center

Kubberød, Elin; Pettersen, Inger Beate

2017-01-01

Purpose: Building on entrepreneurial learning research, the purpose of this paper is to argue that the students participating in foreign entrepreneurial education programmes can have realistic entrepreneurial learning experiences. This research addresses two specific questions: how situated ambiguity induced by a foreign culture may contribute to…

Learning, Teaching and Ambiguity in Virtual Worlds

NASA Astrophysics Data System (ADS)

Carr, Diane; Oliver, Martin; Burn, Andrew

What might online communities and informal learning practices teach us about virtual world pedagogy? In this chapter we describe a research project in which learning practices in online worlds such as World of Warcraft and Second LifeTM (SL) were investigated. Working within an action research framework, we employed a range of methods to investigate how members of online communities define the worlds they encounter, negotiate the terms of participation, and manage the incremental complexity of game worlds. The implications of such practices for online pedagogy were then explored through teaching in SL. SL eludes simple definitions. Users, or "residents", of SL partake of a range of pleasures and activities - socialising, building, creating and exhibiting art, playing games, exploring, shopping, or running a business, for instance. We argue that the variable nature of SL gives rise to degrees of ambiguity. This ambiguity impacts on inworld social practices, and has significant implications for online teaching and learning.

Hippocampal Processing of Ambiguity Enhances Fear Memory

PubMed Central

Amadi, Ugwechi; Lim, Seh Hong; Liu, Elizabeth; Baratta, Michael V.; Goosens, Ki Ann

2016-01-01

Despite the ubiquitous use of Pavlovian fear conditioning as a model for fear learning, the highly predictable conditions used in the laboratory do not resemble real-world conditions, where dangerous situations can lead to unpleasant outcomes in unpredictable ways. Here we varied the timing of aversive events following predictive cues in rodents and discovered that temporal ambiguity of aversive events greatly enhances fear. During fear conditioning with unpredictably timed aversive events, pharmacological inactivation of the dorsal hippocampus or optogenetic silencing of CA1 cells during aversive negative prediction errors prevented this enhancement of fear without impacting fear learning for predictable events. Dorsal hippocampal inactivation also prevented ambiguity-related enhancement of fear during auditory fear conditioning under a partial reinforcement schedule. These results reveal that information about the timing and occurrence of aversive events is rapidly acquired and that unexpectedly timed or omitted aversive events generate hippocampal signals to enhance fear learning. PMID:28182526

Hippocampal Processing of Ambiguity Enhances Fear Memory.

PubMed

Amadi, Ugwechi; Lim, Seh Hong; Liu, Elizabeth; Baratta, Michael V; Goosens, Ki A

2017-02-01

Despite the ubiquitous use of Pavlovian fear conditioning as a model for fear learning, the highly predictable conditions used in the laboratory do not resemble real-world conditions, in which dangerous situations can lead to unpleasant outcomes in unpredictable ways. In the current experiments, we varied the timing of aversive events after predictive cues in rodents and discovered that temporal ambiguity of aversive events greatly enhances fear. During fear conditioning with unpredictably timed aversive events, pharmacological inactivation of the dorsal hippocampus or optogenetic silencing of cornu ammonis 1 cells during aversive negative prediction errors prevented this enhancement of fear without affecting fear learning for predictable events. Dorsal hippocampal inactivation also prevented ambiguity-related enhancement of fear during auditory fear conditioning under a partial-reinforcement schedule. These results reveal that information about the timing and occurrence of aversive events is rapidly acquired and that unexpectedly timed or omitted aversive events generate hippocampal signals to enhance fear learning.

Mentoring relationships and the levels of role conflict and role ambiguity experienced by novice nursing faculty.

PubMed

Specht, Jennifer A

2013-01-01

This study explored the effect of mentoring on the levels of role conflict and role ambiguity experienced by novice nursing faculty related to their transitions into academe using a descriptive, comparative design. It also measured the relationship between the quality of mentoring experiences of novice nursing faculty and their levels of role conflict and role ambiguity using a correlational design. P. Benner's (1984) novice to expert model was utilized as a framework for successful role transition. J. R. Rizzo, R. J. House, and S. I. Lirtzman's (1970) role conflict and role ambiguity scale was used to measure the levels of role conflict and role ambiguity experienced by novice nursing faculty. Results indicate that participants (n = 224) who were mentored have significantly lower levels of role conflict (M = 3.57) and role ambiguity (M = 3.02) than those who were not mentored (M = 4.62 and M = 3.90, respectively). Also significant, the higher the participants' reported levels of quality of mentoring experiences were, the lower their levels of role conflict and role ambiguity were. The results of this study indicate that mentoring eases the transition of novice nursing faculty from practice into academe by decreasing the degree of role ambiguity and role conflict that they experience. © 2013.

Medical Student and Junior Doctors' Tolerance of Ambiguity: Development of a New Scale

ERIC Educational Resources Information Center

Hancock, Jason; Roberts, Martin; Monrouxe, Lynn; Mattick, Karen

2015-01-01

The practice of medicine involves inherent ambiguity, arising from limitations of knowledge, diagnostic problems, complexities of treatment and outcome and unpredictability of patient response. Research into doctors' tolerance of ambiguity is hampered by poor conceptual clarity and inadequate measurement scales. We aimed to create and pilot a…

The tell-tale heart: physiological reactivity during resolution of ambiguity in youth anxiety.

PubMed

Rozenman, Michelle; Vreeland, Allison; Iglesias, Marisela; Mendez, Melissa; Piacentini, John

2018-03-01

In the past decade, cognitive biases and physiological arousal have each been proposed as mechanisms through which paediatric anxiety develops and is maintained over time. Preliminary studies have found associations between anxious interpretations of ambiguity, physiological arousal, and avoidance, supporting theories that link cognition, psychophysiology, and behaviour. However, little is known about the relationship between youths' resolutions of ambiguity and physiological arousal during acute stress. Such information may have important clinical implications for use of verbal self-regulation strategies and cognitive restructuring during treatments for paediatric anxiety. In this brief report, we present findings suggesting that anxious, but not typically developing, youth select avoidant goals via non-threatening resolution of ambiguity during a stressor, and that this resolution of ambiguity is accompanied by physiological reactivity (heart rate, heart rate variability, and respiratory sinus arrhythmia). We propose future empirical research on the interplay between interpretation bias, psychophysiology, and child anxiety, as well as clinical implications.

Application of the multiple PRF technique to resolve Doppler centroid estimation ambiguity for spaceborne SAR

NASA Technical Reports Server (NTRS)

Chang, C. Y.; Curlander, J. C.

1992-01-01

Estimation of the Doppler centroid ambiguity is a necessary element of the signal processing for SAR systems with large antenna pointing errors. Without proper resolution of the Doppler centroid estimation (DCE) ambiguity, the image quality will be degraded in the system impulse response function and the geometric fidelity. Two techniques for resolution of DCE ambiguity for the spaceborne SAR are presented; they include a brief review of the range cross-correlation technique and presentation of a new technique using multiple pulse repetition frequencies (PRFs). For SAR systems, where other performance factors control selection of the PRF's, an algorithm is devised to resolve the ambiguity that uses PRF's of arbitrary numerical values. The performance of this multiple PRF technique is analyzed based on a statistical error model. An example is presented that demonstrates for the Shuttle Imaging Radar-C (SIR-C) C-band SAR, the probability of correct ambiguity resolution is higher than 95 percent for antenna attitude errors as large as 3 deg.

Anxiety and the interpretation of ambiguous information: beyond the emotion-congruent effect.

PubMed

Blanchette, Isabelle; Richards, Anne

2003-06-01

The authors investigated how anxiety influences the use of contextual information in the resolution of ambiguity. Participants heard ambiguous homophones (threat/neutral, positive/neural, and neutral/neutral) with related contextual information. State anxiety was manipulated experimentally. The interpretations of anxious participants were influenced by context to a greater extent than those of control participants. Some mood-incongruent effects were observed where anxious participants were more likely to adopt neutral interpretations of potentially threatening stimuli. Effects were observed in a spelling task (Experiments 1 and 2) and in a lexical decision task (Experiment 3), with supraliminal, and subliminal presentation of contextual cues, and with 2 different anxiety-induction procedures. Results show how anxiety affects both the content and the process of resolution of ambiguity.

How Hispanic Patients Address Ambiguous versus Unambiguous Bias in the Doctor's Office

PubMed Central

Bean, Meghan G.; Covarrubias, Rebecca; Stone, Jeff

2014-01-01

Two studies examined Hispanic individuals’ preferences for using ten different bias reduction strategies when interacting with a doctor whose beliefs about their group were either ambiguous or clearly biased. Consistent with predictions, participants who imagined interacting with a doctor whose beliefs were ambiguous preferred strategies that facilitate positive doctor-patient interactions, whereas participants whose doctor explicitly endorsed negative stereotypes about their group preferred strategies that address stereotype content. The results also revealed that, regardless of whether the doctor's beliefs were ambiguous or clearly biased, stigma consciousness predicted participants’ preferences for using strategies that address stereotype content. These findings suggest that both doctors’ behavior and individual-level factors influence how minority individuals choose to behave in a healthcare setting. PMID:25395691

Ambiguity Of Doppler Centroid In Synthetic-Aperture Radar

NASA Technical Reports Server (NTRS)

Chang, Chi-Yung; Curlander, John C.

1991-01-01

Paper discusses performances of two algorithms for resolution of ambiguity in estimated Doppler centroid frequency of echoes in synthetic-aperture radar. One based on range-cross-correlation technique, other based on multiple-pulse-repetition-frequency technique.

Instantaneous and controllable integer ambiguity resolution: review and an alternative approach

NASA Astrophysics Data System (ADS)

Zhang, Jingyu; Wu, Meiping; Li, Tao; Zhang, Kaidong

2015-11-01

In the high-precision application of Global Navigation Satellite System (GNSS), integer ambiguity resolution is the key step to realize precise positioning and attitude determination. As the necessary part of quality control, integer aperture (IA) ambiguity resolution provides the theoretical and practical foundation for ambiguity validation. It is mainly realized by acceptance testing. Due to the constraint of correlation between ambiguities, it is impossible to realize the controlling of failure rate according to analytical formula. Hence, the fixed failure rate approach is implemented by Monte Carlo sampling. However, due to the characteristics of Monte Carlo sampling and look-up table, we have to face the problem of a large amount of time consumption if sufficient GNSS scenarios are included in the creation of look-up table. This restricts the fixed failure rate approach to be a post process approach if a look-up table is not available. Furthermore, if not enough GNSS scenarios are considered, the table may only be valid for a specific scenario or application. Besides this, the method of creating look-up table or look-up function still needs to be designed for each specific acceptance test. To overcome these problems in determination of critical values, this contribution will propose an instantaneous and CONtrollable (iCON) IA ambiguity resolution approach for the first time. The iCON approach has the following advantages: (a) critical value of acceptance test is independently determined based on the required failure rate and GNSS model without resorting to external information such as look-up table; (b) it can be realized instantaneously for most of IA estimators which have analytical probability formulas. The stronger GNSS model, the less time consumption; (c) it provides a new viewpoint to improve the research about IA estimation. To verify these conclusions, multi-frequency and multi-GNSS simulation experiments are implemented. Those results show that IA

An Analysis of the Associations between Ambiguity Tolerance and EFL Reading Strategy Awareness

ERIC Educational Resources Information Center

Kamran, Saeedeh Karbalaee; Maftoon, Parviz

2012-01-01

The current study is an attempt to investigate whether any statistically significant relationship existed between Iranian EFL learners' ambiguity tolerance (AT) and their reading strategy use. To this end, three instruments of Survey of Reading Strategy (Mokhtari & Sheorey, 2002), Second Language Ambiguity Tolerance Scale (Ely, 1995), and a…

Ambiguities: residents' experience of 'nursing home as my home'.

PubMed

Nakrem, Sigrid; Vinsnes, Anne G; Harkless, Gene E; Paulsen, Bård; Seim, Arnfinn

2013-09-01

Residential care in nursing homes continues to be necessary for those individuals who are no longer able to live at home. Uncovering what nursing home residents' view as quality of care in nursing homes will help further understanding of how best to provide high quality, person-centred care. To describe residents' experiences of living in a nursing home related to quality of care. The study utilises a descriptive exploratory design. In-depth interviews were undertaken with 15 residents who were not cognitively impaired, aged 65 and over and living in one of four nursing homes. The interviews were transcribed verbatim and analysed by categorising of meaning. Residents perceived the nursing home as their home, but at the same time not 'a home'. This essential ambiguity created the tension from which the categories of perceptions of quality emerged. Four main categories of quality of care experience were identified: 'Being at home in a nursing home', 'Paying the price for 24-hour care', 'Personal habits and institutional routines', and 'Meaningful activities for a meaningful day'. Ambiguities concerning the nursing home as a home and place to live, a social environment in which the residents experience most of their social life and the institution where professional health service is provided were uncovered. High-quality care was when ambiguities were managed well and a home could be created within the institution. Implication for practice. Achieving quality care in nursing homes requires reconciling the ambiguities of the nursing home as a home. This implies helping residents to create a private home distinct from the professional home, allowing residents' personal habits to guide institutional routines and supporting meaningful activities. Using these resident developed quality indicators is an important step in improving nursing home services. © 2012 Blackwell Publishing Ltd.

The input ambiguity hypothesis and case blindness: an account of cross-linguistic and intra-linguistic differences in case errors.

PubMed

Pelham, Sabra D

2011-03-01

English-acquiring children frequently make pronoun case errors, while German-acquiring children rarely do. Nonetheless, German-acquiring children frequently make article case errors. It is proposed that when child-directed speech contains a high percentage of case-ambiguous forms, case errors are common in child language; when percentages are low, case errors are rare. Input to English and German children was analyzed for percentage of case-ambiguous personal pronouns on adult tiers of corpora from 24 English-acquiring and 24 German-acquiring children. Also analyzed for German was the percentage of case-ambiguous articles. Case-ambiguous pronouns averaged 63·3% in English, compared with 7·6% in German. The percentage of case-ambiguous articles in German was 77·0%. These percentages align with the children's errors reported in the literature. It appears children may be sensitive to levels of ambiguity such that low ambiguity may aid error-free acquisition, while high ambiguity may blind children to case distinctions, resulting in errors.

Learning and Generalization under Ambiguity: An fMRI Study

PubMed Central

Chumbley, J. R.; Flandin, G.; Bach, D. R.; Daunizeau, J.; Fehr, E.; Dolan, R. J.; Friston, K. J.

2012-01-01

Adaptive behavior often exploits generalizations from past experience by applying them judiciously in new situations. This requires a means of quantifying the relative importance of prior experience and current information, so they can be balanced optimally. In this study, we ask whether the brain generalizes in an optimal way. Specifically, we used Bayesian learning theory and fMRI to test whether neuronal responses reflect context-sensitive changes in ambiguity or uncertainty about experience-dependent beliefs. We found that the hippocampus expresses clear ambiguity-dependent responses that are associated with an augmented rate of learning. These findings suggest candidate neuronal systems that may be involved in aberrations of generalization, such as over-confidence. PMID:22275857

Learning and generalization under ambiguity: an fMRI study.

PubMed

Chumbley, J R; Flandin, G; Bach, D R; Daunizeau, J; Fehr, E; Dolan, R J; Friston, K J

2012-01-01

Adaptive behavior often exploits generalizations from past experience by applying them judiciously in new situations. This requires a means of quantifying the relative importance of prior experience and current information, so they can be balanced optimally. In this study, we ask whether the brain generalizes in an optimal way. Specifically, we used Bayesian learning theory and fMRI to test whether neuronal responses reflect context-sensitive changes in ambiguity or uncertainty about experience-dependent beliefs. We found that the hippocampus expresses clear ambiguity-dependent responses that are associated with an augmented rate of learning. These findings suggest candidate neuronal systems that may be involved in aberrations of generalization, such as over-confidence.

Implicit and Explicit Understanding of Ambiguous Figures by Adolescents with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Allen, Melissa L.; Chambers, Alison

2011-01-01

Children with autism spectrum disorder (ASD) can process both interpretations of an ambiguous figure (e.g. rabbit/duck) when told about the ambiguity, however they tend not to do so spontaneously. Here we show that although adolescents with ASD can explicitly experience such "reversals", implicit measures suggest they are conceptually…

Ambiguity Advantage Revisited: Two Meanings Are Better than One when Accessing Chinese Nouns

ERIC Educational Resources Information Center

Lin, Chien-Jer Charles; Ahrens, Kathleen

2010-01-01

This paper revisits the effect of lexical ambiguity in word recognition, which has been controversial as previous research reported advantage, disadvantage, and null effects. We discuss factors that were not consistently treated in previous research (e.g., the level of lexical ambiguity investigated, parts of speech of the experimental stimuli,…

Morpho-Semantic Processing in Word Recognition: Evidence from Balanced and Biased Ambiguous Morphemes

ERIC Educational Resources Information Center

Tsang, Yiu-Kei; Chen, Hsuan-Chih

2013-01-01

The role of morphemic meaning in Chinese word recognition was examined with the masked and unmasked priming paradigms. Target words contained ambiguous morphemes biased toward the dominant or the subordinate meanings. Prime words either contained the same ambiguous morphemes in the subordinate interpretations or were unrelated to the targets. In…

Sensitivity to Referential Ambiguity in Discourse: The Role of Attention, Working Memory, and Verbal Ability

PubMed Central

Boudewyn, Megan A.; Long, Debra L.; Traxler, Matthew J.; Lesh, Tyler A.; Dave, Shruti; Mangun, George R.; Carter, Cameron S.; Swaab, Tamara Y.

2016-01-01

The establishment of reference is essential to language comprehension. The goal of this study was to examine listeners’ sensitivity to referential ambiguity as a function of individual variation in attention, working memory capacity, and verbal ability. Participants listened to stories in which two entities were introduced that were either very similar (e.g., two oaks) or less similar (e.g., one oak and one elm). The manipulation rendered an anaphor in a subsequent sentence (e.g., oak) ambiguous or unambiguous. EEG was recorded as listeners comprehended the story, after which participants completed tasks to assess working memory, verbal ability, and the ability to use context in task performance. Power in the alpha and theta frequency bands when listeners received critical information about the discourse entities (e.g., oaks) was used to index attention and the involvement of the working memory system in processing the entities. These measures were then used to predict an ERP component that is sensitive to referential ambiguity, the Nref, which was recorded when listeners received the anaphor. Nref amplitude at the anaphor was predicted by alpha power during the earlier critical sentence: Individuals with increased alpha power in ambiguous compared with unambiguous stories were less sensitive to the anaphor's ambiguity. Verbal ability was also predictive of greater sensitivity to referential ambiguity. Finally, increased theta power in the ambiguous compared with unambiguous condition was associated with higher working-memory span. These results highlight the role of attention and working memory in referential processing during listening comprehension. PMID:26401815

Sensitivity to Referential Ambiguity in Discourse: The Role of Attention, Working Memory, and Verbal Ability.

PubMed

Boudewyn, Megan A; Long, Debra L; Traxler, Matthew J; Lesh, Tyler A; Dave, Shruti; Mangun, George R; Carter, Cameron S; Swaab, Tamara Y

2015-12-01

The establishment of reference is essential to language comprehension. The goal of this study was to examine listeners' sensitivity to referential ambiguity as a function of individual variation in attention, working memory capacity, and verbal ability. Participants listened to stories in which two entities were introduced that were either very similar (e.g., two oaks) or less similar (e.g., one oak and one elm). The manipulation rendered an anaphor in a subsequent sentence (e.g., oak) ambiguous or unambiguous. EEG was recorded as listeners comprehended the story, after which participants completed tasks to assess working memory, verbal ability, and the ability to use context in task performance. Power in the alpha and theta frequency bands when listeners received critical information about the discourse entities (e.g., oaks) was used to index attention and the involvement of the working memory system in processing the entities. These measures were then used to predict an ERP component that is sensitive to referential ambiguity, the Nref, which was recorded when listeners received the anaphor. Nref amplitude at the anaphor was predicted by alpha power during the earlier critical sentence: Individuals with increased alpha power in ambiguous compared with unambiguous stories were less sensitive to the anaphor's ambiguity. Verbal ability was also predictive of greater sensitivity to referential ambiguity. Finally, increased theta power in the ambiguous compared with unambiguous condition was associated with higher working-memory span. These results highlight the role of attention and working memory in referential processing during listening comprehension.

Developmental evaluation of family functioning deficits in youths and young adults with childhood-onset bipolar disorder.

PubMed

MacPherson, Heather A; Ruggieri, Amanda L; Christensen, Rachel E; Schettini, Elana; Kim, Kerri L; Thomas, Sarah A; Dickstein, Daniel P

2018-08-01

Childhood-onset bipolar disorder (BD) is a serious condition that affects the patient and family. While research has documented familial dysfunction in individuals with BD, no studies have compared developmental differences in family functioning in youths with BD vs. adults with prospectively verified childhood-onset BD. The Family Assessment Device (FAD) was used to examine family functioning in participants with childhood-onset BD (n = 116) vs. healthy controls (HCs) (n = 108), ages 7-30 years, using multivariate analysis of covariance and multiple linear regression. Participants with BD had significantly worse family functioning in all domains (problem solving, communication, roles, affective responsiveness, affective involvement, behavior control, general functioning) compared to HCs, regardless of age, IQ, and socioeconomic status. Post-hoc analyses suggested no influence for mood state, global functioning, comorbidity, and most medications, despite youths with BD presenting with greater severity in these areas than adults. Post-hoc tests eliminating participants taking lithium (n = 17) showed a significant diagnosis-by-age interaction: youths with BD had worse family problem solving and communication relative to HCs. Limitations include the cross-sectional design, clinical differences in youths vs. adults with BD, ambiguity in FAD instructions, participant-only report of family functioning, and lack of data on psychosocial treatments. Familial dysfunction is common in childhood-onset BD and endures into adulthood. Early identification and treatment of both individual and family impairments is crucial. Further investigation into multi-level, family-based mechanisms underlying childhood-onset BD may clarify the role family factors play in the disorder, and offer avenues for the development of novel, family-focused therapeutic strategies. Copyright © 2018 Elsevier B.V. All rights reserved.

Role Conflict and Ambiguity as Predictors of Job Satisfaction in High School Counselors

ERIC Educational Resources Information Center

Cervoni, Annemarie; DeLucia-Waack, Janice

2011-01-01

The purpose of this study was to examine the relationship between role conflict and role ambiguity, and percentage of time spent on ASCA recommended duties (counseling, coordination, consultation, and large group guidance); and job satisfaction of high school counselors. The Role Conflict and Role Ambiguity Scale and the Job Descriptive Index were…

From expert generalists to ambiguity masters: using ambiguity tolerance theory to redefine the practice of rural nurses.

PubMed

Knight, Kaye; Kenny, Amanda; Endacott, Ruth

2016-06-01

To redefine the practice of rural nurses and describe a model that conceptualises the capabilities and characteristics required in the rural environment. The way in which the practice of rural nurses has been conceptualised is problematic. Definitions of rural nursing have been identified primarily through the functional context of rural health service delivery. The expert generalist term has provided a foundation theory for rural nurses with understandings informed by the scope of practice needed to meet service delivery requirements. However, authors exploring intrinsic characteristics of rural nurses have challenged this definition, as it does not adequately address the deeper, intangible complexities of practice required in the rural context. Despite this discourse, an alternative way to articulate the distinctive nature of rural nursing practice has eluded authors in Australia and internationally. A theoretical paper based on primary research. The development of the model was informed by the findings of a study that explored the nursing practice of managing telephone presentations in rural health services in Victoria, Australia. The study involved policy review from State and Federal governments, nursing and medical professional bodies, and five rural health services; semi-structured interviews with eight Directors of Nursing, seven registered nurses and focus group interviews with eight registered nurses. An ambiguity tolerance model drawn from corporate global entrepreneurship theory was adapted to explain the findings of the study. The adapted model presents capabilities and characteristics used by nurses to successfully manage the ambiguity of providing care in the rural context. Redefining the practice of rural nurses, through an adapted theory of ambiguity tolerance, highlights nursing characteristics and capabilities required in the rural context. This perspective offers new ways of thinking about the work of rural nurses, rural nurse policy, education

Resolving the Azimuthal Ambiguity in Vector Magnetogram Data with the Divergence-Free Condition: Theoretical Examination

NASA Technical Reports Server (NTRS)

Crouch, A.; Barnes, G.

2008-01-01

We demonstrate that the azimuthal ambiguity that is present in solar vector magnetogram data can be resolved with line-of-sight and horizontal heliographic derivative information by using the divergence-free property of magnetic fields without additional assumptions. We discuss the specific derivative information that is sufficient to resolve the ambiguity away from disk center, with particular emphasis on the line-of-sight derivative of the various components of the magnetic field. Conversely, we also show cases where ambiguity resolution fails because sufficient line-of-sight derivative information is not available. For example, knowledge of only the line-of-sight derivative of the line-of-sight component of the field is not sufficient to resolve the ambiguity away from disk center.

Empirical links between trace metal cycling and marine microbial ecology during a large perturbation to Earth's carbon cycle

NASA Astrophysics Data System (ADS)

Owens, Jeremy D.; Reinhard, Christopher T.; Rohrssen, Megan; Love, Gordon D.; Lyons, Timothy W.

2016-09-01

Understanding the global redox state of the oceans and its cause-and-effect relationship with periods of widespread organic-carbon deposition is vital to interpretations of Earth's climatic and biotic feedbacks during periods of expanded oceanic oxygen deficiency. Here, we present a compilation of new and published data from an organic-rich locality within the proto-North Atlantic Ocean during the Cenomanian-Turonian boundary event that shows a dramatic drawdown of redox-sensitive trace elements. Iron geochemistry independently suggests euxinic deposition (i.e., anoxic and sulfidic bottom waters) for the entire section, thus confirming its potential as an archive of global marine metal inventories. In particular, depleted molybdenum (Mo) and vanadium (V) concentrations effectively record the global expansion of euxinic and oxygen-deficient but non-sulfidic waters, respectively. The V drawdown precedes the OAE, fingerprinting an expansion of oxygen deficiency prior to an expansion of euxinia. Molybdenum drawdown, in contrast, is delayed with respect to V and coincides with the onset of OAE2. Parallel lipid biomarker analyses provide evidence for significant and progressive reorganization of marine microbial ecology during the OAE in this region of the proto-North Atlantic, with the smallest relative eukaryotic contributions to total primary production occurring during metal-depleted intervals. This relationship may be related to decreasing supplies of enzymatically important trace elements. Similarly, box modeling suggests that oceanic drawdown of Mo may have approached levels capable of affecting marine nitrogen fixation. Predictions of possible nitrogen stress on eukaryotic production, locally and globally, are consistent with the low observed levels of Mo and a rise in 2-methylhopane index values during the peak of the OAE. At the same time, the environmental challenge presented by low dissolved oxygen and euxinia coincides with increased turnover rates of

Enhancement of Directional Ambiguity Removal Skill in Scatterometer Data Processing Using Planetary Boundary Layer Models

NASA Technical Reports Server (NTRS)

Kim, Young-Joon; Pak, Kyung S.; Dunbar, R. Scott; Hsiao, S. Vincent; Callahan, Philip S.

2000-01-01

Planetary boundary layer (PBL) models are utilized to enhance directional ambiguity removal skill in scatterometer data processing. The ambiguity in wind direction retrieved from scatterometer measurements is removed with the aid of physical directional information obtained from PBL models. This technique is based on the observation that sea level pressure is scalar and its field is more coherent than the corresponding wind. An initial wind field obtained from the scatterometer measurements is used to derive a pressure field with a PBL model. After filtering small-scale noise in the derived pressure field, a wind field is generated with an inverted PBL model. This derived wind information is then used to remove wind vector ambiguities in the scatterometer data. It is found that the ambiguity removal skill can be improved when the new technique is used properly in conjunction with the median filter being used for scatterometer wind dealiasing at JPL. The new technique is applied to regions of cyclone systems which are important for accurate weather prediction but where the errors of ambiguity removal are often large.

Interpretative bias in spider phobia: Perception and information processing of ambiguous schematic stimuli.

PubMed

Haberkamp, Anke; Schmidt, Filipp

2015-09-01

This study investigates the interpretative bias in spider phobia with respect to rapid visuomotor processing. We compared perception, evaluation, and visuomotor processing of ambiguous schematic stimuli between spider-fearful and control participants. Stimuli were produced by gradually morphing schematic flowers into spiders. Participants rated these stimuli related to their perceptual appearance and to their feelings of valence, disgust, and arousal. Also, they responded to the same stimuli within a response priming paradigm that measures rapid motor activation. Spider-fearful individuals showed an interpretative bias (i.e., ambiguous stimuli were perceived as more similar to spiders) and rated spider-like stimuli as more unpleasant, disgusting, and arousing. However, we observed no differences between spider-fearful and control participants in priming effects for ambiguous stimuli. For non-ambiguous stimuli, we observed a similar enhancement for phobic pictures as has been reported previously for natural images. We discuss our findings with respect to the visual representation of morphed stimuli and to perceptual learning processes. Copyright © 2015 Elsevier B.V. All rights reserved.

Flexible taxonomic assignment of ambiguous sequencing reads

PubMed Central

2011-01-01

Background To characterize the diversity of bacterial populations in metagenomic studies, sequencing reads need to be accurately assigned to taxonomic units in a given reference taxonomy. Reads that cannot be reliably assigned to a unique leaf in the taxonomy (ambiguous reads) are typically assigned to the lowest common ancestor of the set of species that match it. This introduces a potentially severe error in the estimation of bacteria present in the sample due to false positives, since all species in the subtree rooted at the ancestor are implicitly assigned to the read even though many of them may not match it. Results We present a method that maps each read to a node in the taxonomy that minimizes a penalty score while balancing the relevance of precision and recall in the assignment through a parameter q. This mapping can be obtained in time linear in the number of matching sequences, because LCA queries to the reference taxonomy take constant time. When applied to six different metagenomic datasets, our algorithm produces different taxonomic distributions depending on whether coverage or precision is maximized. Including information on the quality of the reads reduces the number of unassigned reads but increases the number of ambiguous reads, stressing the relevance of our method. Finally, two measures of performance are described and results with a set of artificially generated datasets are discussed. Conclusions The assignment strategy of sequencing reads introduced in this paper is a versatile and a quick method to study bacterial communities. The bacterial composition of the analyzed samples can vary significantly depending on how ambiguous reads are assigned depending on the value of the q parameter. Validation of our results in an artificial dataset confirm that a combination of values of q produces the most accurate results. PMID:21211059

Teachers' Burnout, Depression, Role Ambiguity and Conflict

ERIC Educational Resources Information Center

Papastylianou, Antonia; Kaila, Maria; Polychronopoulos, Michael

2009-01-01

The present study investigates issues associated with teachers' burnout in primary education as related to depression and role conflict-ambiguity. At the time of the study the participants (562 teachers) were working in seventy nine (79) Primary Education State Schools in Greece (Athens and two prefectures in the southern part of the country). The…

Physical condition for elimination of ambiguity in conditionally convergent lattice sums

NASA Astrophysics Data System (ADS)

Young, K.

1987-02-01

The conditional convergence of the lattice sum defining the Madelung constant gives rise to an ambiguity in its value. It is shown that this ambiguity is related, through a simple and universal integral, to the average charge density on the crystal surface. The physically correct value is obtained by setting the charge density to zero. A simple and universally applicable formula for the Madelung constant is derived as a consequence. It consists of adding up dipole-dipole energies together with a nontrivial correction term.

Breaking the indexing ambiguity in serial crystallography.

PubMed

Brehm, Wolfgang; Diederichs, Kay

2014-01-01

In serial crystallography, a very incomplete partial data set is obtained from each diffraction experiment (a `snapshot'). In some space groups, an indexing ambiguity exists which requires that the indexing mode of each snapshot needs to be established with respect to a reference data set. In the absence of such re-indexing information, crystallographers have thus far resorted to a straight merging of all snapshots, yielding a perfectly twinned data set of higher symmetry which is poorly suited for structure solution and refinement. Here, two algorithms have been designed for assembling complete data sets by clustering those snapshots that are indexed in the same way, and they have been tested using 15,445 snapshots from photosystem I [Chapman et al. (2011), Nature (London), 470, 73-77] and with noisy model data. The results of the clustering are unambiguous and enabled the construction of complete data sets in the correct space group P63 instead of (twinned) P6322 that researchers have been forced to use previously in such cases of indexing ambiguity. The algorithms thus extend the applicability and reach of serial crystallography.

Childhood adversity, early-onset depressive/anxiety disorders, and adult-onset asthma.

PubMed

Scott, Kate M; Von Korff, Michael; Alonso, Jordi; Angermeyer, Matthias C; Benjet, Corina; Bruffaerts, Ronny; de Girolamo, Giovanni; Haro, Josep Maria; Kessler, Ronald C; Kovess, Viviane; Ono, Yutaka; Ormel, Johan; Posada-Villa, José

2008-11-01

To investigate a) whether childhood adversity predicts adult-onset asthma; b) whether early-onset depressive/anxiety disorders predict adult-onset asthma; and c) whether childhood adversity and early-onset depressive/anxiety disorders predict adult-onset asthma independently of each other. Previous research has suggested, but not established, that childhood adversity may predict adult-onset asthma and, moreover, that the association between mental disorders and asthma may be a function of shared risk factors, such as childhood adversity. Ten cross-sectional population surveys of household-residing adults (>18 years, n = 18,303) assessed mental disorders with the Composite International Diagnostic Interview (CIDI 3.0) as part of the World Mental Health surveys. Assessment of a range of childhood family adversities was included. Asthma was ascertained by self-report of lifetime diagnosis and age of diagnosis. Survival analyses calculated hazard ratios (HRs) for risk of adult-onset (>age 20 years) asthma as a function of number and type of childhood adversities and early-onset (onset asthma with risk increasing with the number of adversities experienced (HRs = 1.49-1.71). Early-onset depressive and anxiety disorders also predicted adult-onset asthma (HRs = 1.67-2.11). Childhood adversities and early-onset depressive and anxiety disorders both predicted adult-onset asthma after mutual adjustment (HRs = 1.43-1.91). Childhood adversities and early-onset depressive/anxiety disorders independently predict adult-onset asthma, suggesting that the mental disorder-asthma relationship is not a function of a shared background of childhood adversity.

Who is respectful? Effects of social context and individual empathic ability on ambiguity resolution during utterance comprehension

PubMed Central

Jiang, Xiaoming; Zhou, Xiaolin

2015-01-01

Verbal communication is often ambiguous. By employing the event-related potential (ERP) technique, this study investigated how a comprehender resolves referential ambiguity by using information concerning the social status of communicators. Participants read a conversational scenario which included a minimal conversational context describing a speaker and two other persons of the same or different social status and a directly quoted utterance. A singular, second-person pronoun in the respectful form (nin/nin-de in Chinese) in the utterance could be ambiguous with respect to which of the two persons was the addressee (the “Ambiguous condition”). Alternatively, the pronoun was not ambiguous either because one of the two persons was of higher social status and hence should be the addressee according to social convention (the “Status condition”) or because a word referring to the status of a person was additionally inserted before the pronoun to help indicate the referent of the pronoun (the “Referent condition”). Results showed that the perceived ambiguity decreased over the Ambiguous, Status, and Referent conditions. Electrophysiologically, the pronoun elicited an increased N400 in the Referent than in the Status and the Ambiguous conditions, reflecting an increased integration demand due to the necessity of linking the pronoun to both its antecedent and the status word. Relative to the Referent condition, a late, sustained positivity was elicited for the Status condition starting from 600 ms, while a more delayed, anterior negativity was elicited for the Ambiguous condition. Moreover, the N400 effect was modulated by individuals' sensitivity to the social status information, while the late positivity effect was modulated by individuals' empathic ability. These findings highlight the neurocognitive flexibility of contextual bias in referential processing during utterance comprehension. PMID:26557102

Preliminary validation of the Spanish version of the Multiple Stimulus Types Ambiguity Tolerance Scale (MSTAT-II).

PubMed

Arquero, José L; McLain, David L

2010-05-01

Despite widespread interest in ambiguity tolerance and other information-related individual differences, existing measures are conceptually dispersed and psychometrically weak. This paper presents the Spanish version of MSTAT-II, a short, stimulus-oriented, and psychometrically improved measure of an individual's orientation toward ambiguous stimuli. Results obtained reveal adequate reliability, validity, and temporal stability. These results support the use of MSTAT-II as an adequate measure of ambiguity tolerance.

Enhancing lexical ambiguity resolution by brain polarization of the right posterior superior temporal sulcus.

PubMed

Peretz, Yael; Lavidor, Michal

2013-04-01

Previous studies have reported a hemispheric asymmetry in processing dominant (e.g., paper) and subordinate (e.g., farmer) associations of ambiguous words (pen). Here we applied sham and anodal Transcranial Direct Current Stimulation (tDCS) over Wernicke's area and its right homologue to test whether we can modulate the selective hemispheric expertise in processing lexical ambiguity. Ambiguous prime words were presented followed by target words that could be associated to the dominant or subordinate meaning of the prime in a semantic relatedness task. Anodal stimulation of the right Wernicke's area significantly decreased response time (RTs) to subordinate but not dominant associations compared to sham stimulation. There was also a complementary trend of faster responses to dominant associations following anodal stimulation of Wernicke's area. The results support brain asymmetry in processing lexical ambiguity and show that tDCS can enhance complex language processing even in a sample of highly literate individuals. Copyright © 2012 Elsevier Ltd. All rights reserved.

Objective scatterometer wind ambiguity removal using smoothness and dynamical constraints

NASA Technical Reports Server (NTRS)

Hoffman, R. N.

1984-01-01

In the present investigation, a variational analysis method (VAM) is used to remove the ambiguity of the Seasat-A Satellite Scatterometer (SASS) winds. At each SASS data point, two, three, or four wind vectors (termed ambiguities) are retrieved. It is pointed out that the VAM is basically a least squares method for fitting data. The problem may be nonlinear. The best fit to the data and constraints is obtained on the basis of a minimization of the objective function. The VAM was tested and tuned at 12 h GMT Sept. 10, 1978. Attention is given to a case study involving an intense cyclone centered south of Japan at 138 deg E.

A comparison of a two-dimensional variational analysis method and a median filter for NSCAT ambiguity removal

NASA Astrophysics Data System (ADS)

Henderson, J. M.; Hoffman, R. N.; Leidner, S. M.; Atlas, R.; Brin, E.; Ardizzone, J. V.

2003-06-01

The ocean surface vector wind can be measured from space by scatterometers. For a set of measurements observed from several viewing directions and collocated in space and time, there will usually exist two, three, or four consistent wind vectors. These multiple wind solutions are known as ambiguities. Ambiguity removal procedures select one ambiguity at each location. We compare results of two different ambiguity removal algorithms, the operational median filter (MF) used by the Jet Propulsion Laboratory (JPL) and a two-dimensional variational analysis method (2d-VAR). We applied 2d-VAR to the entire NASA Scatterometer (NSCAT) mission, orbit by orbit, using European Centre for Medium-Range Weather Forecasts (ECMWF) 10-m wind analyses as background fields. We also applied 2d-VAR to a 51-day subset of the NSCAT mission using National Centers for Environmental Prediction (NCEP) 1000-hPa wind analyses as background fields. This second data set uses the same background fields as the MF data set. When both methods use the same NCEP background fields as a starting point for ambiguity removal, agreement is very good: Approximately only 3% of the wind vector cells (WVCs) have different ambiguity selections; however, most of the WVCs with changes occur in coherent patches. Since at least one of the selections is in error, this implies that errors due to ambiguity selection are not isolated, but are horizontally correlated. When we examine ambiguity selection differences at synoptic scales, we often find that the 2d-VAR selections are more meteorologically reasonable and more consistent with cloud imagery.

Improving Ambiguity Resolution for Medium Baselines Using Combined GPS and BDS Dual/Triple-Frequency Observations

PubMed Central

Gao, Wang; Gao, Chengfa; Pan, Shuguo; Wang, Denghui; Deng, Jiadong

2015-01-01

The regional constellation of the BeiDou navigation satellite system (BDS) has been providing continuous positioning, navigation and timing services since 27 December 2012, covering China and the surrounding area. Real-time kinematic (RTK) positioning with combined BDS and GPS observations is feasible. Besides, all satellites of BDS can transmit triple-frequency signals. Using the advantages of multi-pseudorange and carrier observations from multi-systems and multi-frequencies is expected to be of much benefit for ambiguity resolution (AR). We propose an integrated AR strategy for medium baselines by using the combined GPS and BDS dual/triple-frequency observations. In the method, firstly the extra-wide-lane (EWL) ambiguities of triple-frequency system, i.e., BDS, are determined first. Then the dual-frequency WL ambiguities of BDS and GPS were resolved with the geometry-based model by using the BDS ambiguity-fixed EWL observations. After that, basic (i.e., L1/L2 or B1/B2) ambiguities of BDS and GPS are estimated together with the so-called ionosphere-constrained model, where the ambiguity-fixed WL observations are added to enhance the model strength. During both of the WL and basic AR, a partial ambiguity fixing (PAF) strategy is adopted to weaken the negative influence of new-rising or low-elevation satellites. Experiments were conducted and presented, in which the GPS/BDS dual/triple-frequency data were collected in Nanjing and Zhengzhou of China, with the baseline distance varying from about 28.6 to 51.9 km. The results indicate that, compared to the single triple-frequency BDS system, the combined system can significantly enhance the AR model strength, and thus improve AR performance for medium baselines with a 75.7% reduction of initialization time on average. Besides, more accurate and stable positioning results can also be derived by using the combined GPS/BDS system. PMID:26528977

Improving Ambiguity Resolution for Medium Baselines Using Combined GPS and BDS Dual/Triple-Frequency Observations.

PubMed

Gao, Wang; Gao, Chengfa; Pan, Shuguo; Wang, Denghui; Deng, Jiadong

2015-10-30

The regional constellation of the BeiDou navigation satellite system (BDS) has been providing continuous positioning, navigation and timing services since 27 December 2012, covering China and the surrounding area. Real-time kinematic (RTK) positioning with combined BDS and GPS observations is feasible. Besides, all satellites of BDS can transmit triple-frequency signals. Using the advantages of multi-pseudorange and carrier observations from multi-systems and multi-frequencies is expected to be of much benefit for ambiguity resolution (AR). We propose an integrated AR strategy for medium baselines by using the combined GPS and BDS dual/triple-frequency observations. In the method, firstly the extra-wide-lane (EWL) ambiguities of triple-frequency system, i.e., BDS, are determined first. Then the dual-frequency WL ambiguities of BDS and GPS were resolved with the geometry-based model by using the BDS ambiguity-fixed EWL observations. After that, basic (i.e., L1/L2 or B1/B2) ambiguities of BDS and GPS are estimated together with the so-called ionosphere-constrained model, where the ambiguity-fixed WL observations are added to enhance the model strength. During both of the WL and basic AR, a partial ambiguity fixing (PAF) strategy is adopted to weaken the negative influence of new-rising or low-elevation satellites. Experiments were conducted and presented, in which the GPS/BDS dual/triple-frequency data were collected in Nanjing and Zhengzhou of China, with the baseline distance varying from about 28.6 to 51.9 km. The results indicate that, compared to the single triple-frequency BDS system, the combined system can significantly enhance the AR model strength, and thus improve AR performance for medium baselines with a 75.7% reduction of initialization time on average. Besides, more accurate and stable positioning results can also be derived by using the combined GPS/BDS system.

Midwestern Millennial University Students' Tolerance for Ambiguity in a Period of Complex World Conflicts

ERIC Educational Resources Information Center

Mahdi, Ghada S.

2012-01-01

Though age and gender do not affect students' knowledge of global issues and associated ambiguity, the academic major of undergraduates did. Students' combined perceptions on knowledge of these issues and their associated ambiguities varied among the four academic groups of majors. Unlike teacher education majors and in combined other majors…

Context sensitivity and ambiguity in component-based systems design

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

Bespalko, S.J.; Sindt, A.

1997-10-01

Designers of components-based, real-time systems need to guarantee to correctness of soft-ware and its output. Complexity of a system, and thus the propensity for error, is best characterized by the number of states a component can encounter. In many cases, large numbers of states arise where the processing is highly dependent on context. In these cases, states are often missed, leading to errors. The following are proposals for compactly specifying system states which allow the factoring of complex components into a control module and a semantic processing module. Further, the need for methods that allow for the explicit representation ofmore » ambiguity and uncertainty in the design of components is discussed. Presented herein are examples of real-world problems which are highly context-sensitive or are inherently ambiguous.« less

Perceptions of racial confrontation: the role of color blindness and comment ambiguity.

PubMed

Zou, Linda X; Dickter, Cheryl L

2013-01-01

Because of its emphasis on diminishing race and avoiding racial discourse, color-blind racial ideology has been suggested to have negative consequences for modern day race relations. The current research examined the influence of color blindness and the ambiguity of a prejudiced remark on perceptions of a racial minority group member who confronts the remark. One hundred thirteen White participants responded to a vignette depicting a White character making a prejudiced comment of variable ambiguity, after which a Black target character confronted the comment. Results demonstrated that the target confronter was perceived more negatively and as responding less appropriately by participants high in color blindness, and that this effect was particularly pronounced when participants responded to the ambiguous comment. Implications for the ways in which color blindness, as an accepted norm that is endorsed across legal and educational settings, can facilitate Whites' complicity in racial inequality are discussed.

Preventing Data Ambiguity in Infectious Diseases with Four-Dimensional and Personalized Evaluations

PubMed Central

Iandiorio, Michelle J.; Fair, Jeanne M.; Chatzipanagiotou, Stylianos; Ioannidis, Anastasios; Trikka-Graphakos, Eleftheria; Charalampaki, Nikoletta; Sereti, Christina; Tegos, George P.; Hoogesteijn, Almira L.; Rivas, Ariel L.

2016-01-01

Background Diagnostic errors can occur, in infectious diseases, when anti-microbial immune responses involve several temporal scales. When responses span from nanosecond to week and larger temporal scales, any pre-selected temporal scale is likely to miss some (faster or slower) responses. Hoping to prevent diagnostic errors, a pilot study was conducted to evaluate a four-dimensional (4D) method that captures the complexity and dynamics of infectious diseases. Methods Leukocyte-microbial-temporal data were explored in canine and human (bacterial and/or viral) infections, with: (i) a non-structured approach, which measures leukocytes or microbes in isolation; and (ii) a structured method that assesses numerous combinations of interacting variables. Four alternatives of the structured method were tested: (i) a noise-reduction oriented version, which generates a single (one data point-wide) line of observations; (ii) a version that measures complex, three-dimensional (3D) data interactions; (iii) a non-numerical version that displays temporal data directionality (arrows that connect pairs of consecutive observations); and (iv) a full 4D (single line-, complexity-, directionality-based) version. Results In all studies, the non-structured approach revealed non-interpretable (ambiguous) data: observations numerically similar expressed different biological conditions, such as recovery and lack of recovery from infections. Ambiguity was also found when the data were structured as single lines. In contrast, two or more data subsets were distinguished and ambiguity was avoided when the data were structured as complex, 3D, single lines and, in addition, temporal data directionality was determined. The 4D method detected, even within one day, changes in immune profiles that occurred after antibiotics were prescribed. Conclusions Infectious disease data may be ambiguous. Four-dimensional methods may prevent ambiguity, providing earlier, in vivo, dynamic, complex, and

Utilization of Prosodic Information in Syntactic Ambiguity Resolution

PubMed Central

2010-01-01

Two self paced listening experiments examined the role of prosodic phrasing in syntactic ambiguity resolution. In Experiment 1, the stimuli consisted of early closure sentences (e.g., “While the parents watched, the child sang a song.”) containing transitive-biased subordinate verbs paired with plausible direct objects or intransitive-biased subordinate verbs paired with implausible direct objects. Experiment 2 also contained early closure sentences with transitively and intransitive-biased subordinate verbs, but the subordinate verbs were always followed by plausible direct objects. In both experiments, there were two prosodic conditions. In the subject-biased prosodic condition, an intonational phrase boundary marked the clausal boundary following the subordinate verb. In the object-biased prosodic condition, the clause boundary was unmarked. The results indicate that lexical and prosodic cues interact at the subordinate verb and plausibility further affects processing at the ambiguous noun. Results are discussed with respect to models of the role of prosody in sentence comprehension. PMID:20033849

Smelling directions: Olfaction modulates ambiguous visual motion perception

PubMed Central

Kuang, Shenbing; Zhang, Tao

2014-01-01

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

The association between tolerance for ambiguity and fear of negative evaluation: A study of engineering technology capstone courses

NASA Astrophysics Data System (ADS)

Dubikovsky, Sergey I.

For many students in engineering and engineering technology programs in the US, senior capstone design courses require students to form a team, define a problem, and find a feasible technical solution to address this problem. Students must integrate the knowledge and skills acquired during their studies at the college or university level. These truly integrative design activities do not have a single "correct" solution. Instead, there is an array of solutions, many of which could be used to achieve the final result. This ambiguity can cause students to experience anxiety during the projects. This study examined the main topics: • To what extent is a social anxiety (measured as fear of negative evaluation) related to tolerance for ambiguity in senior engineering capstone courses? • How does exposure to ambiguity prior to and during capstone courses affect tolerance for ambiguity? The study looked at the standard educational practices to see if they have unintended consequences, such a social anxiety in dealing with ambiguity. Those consequences are highly undesirable because they reduce students' learning. It was hypothesized that the lecture-based approaches that are more common in the first three years of study would not prepare students for self-directed capstone courses because the students would rarely have experienced problem-based learning before. The study used a quantitative approach and examined students' perceptions of their tolerance for ambiguity, and social anxiety before and after their senior capstone design experience. A survey instrument was adapted to measure exposure to ambiguity, which was studied as a potential moderator of the relationship between social anxiety and tolerance for ambiguity. The study indicated that social anxiety, as measured by fear of negative evaluation, does not play a major role in capstone courses. The second finding is that a single course, even if it was administered as a problem-based senior class, failed to

Neurokinin B receptor antagonism decreases luteinising hormone pulse frequency and amplitude and delays puberty onset in the female rat.

PubMed

Li, S Y; Li, X F; Hu, M H; Shao, B; Poston, L; Lightman, S L; O'Byrne, K T

2014-08-01

The neural mechanisms controlling puberty onset remain enigmatic. Humans with loss of function mutations in TAC3 or TACR3, the genes encoding neurokinin B (NKB) or its receptor, neurokinin-3 receptor (NK3R), respectively, present with severe congenital gonadotrophin deficiency and pubertal failure. Animal studies have shown ambiguous actions of NKB-NK3R signalling with respect to controlling puberty onset. The present study aimed to determine the role of endogenous NKB-NK3R signalling in the control of pulsatile luteinising hormone (LH) secretion and the timing of puberty onset, and also whether precocious pubertal onset as a result of an obesogenic diet is similarly regulated by this neuropeptide system. Prepubertal female rats, chronically implanted with i.c.v. cannulae, were administered SB222200, a NK3R antagonist, or artificial cerebrospinal fluid via an osmotic mini-pump for 14 days. SB222200 significantly delayed the onset of vaginal opening and first oestrus (as markers of puberty) compared to controls in both normal and high-fat diet fed animals. Additionally, serial blood sampling, via chronic indwelling cardiac catheters, revealed that the increase in LH pulse frequency was delayed and that the LH pulse amplitude was reduced in response to NK3R antagonism, regardless of dietary status. These data suggest that endogenous NKB-NK3R signalling plays a role in controlling the timing of puberty and the associated acceleration of gonadotrophin-releasing hormone pulse generator frequency in the female rat. © 2014 British Society for Neuroendocrinology.

Measuring the subjective value of risky and ambiguous options using experimental economics and functional MRI methods.

PubMed

Levy, Ifat; Rosenberg Belmaker, Lior; Manson, Kirk; Tymula, Agnieszka; Glimcher, Paul W

2012-09-19

Most of the choices we make have uncertain consequences. In some cases the probabilities for different possible outcomes are precisely known, a condition termed "risky". In other cases when probabilities cannot be estimated, this is a condition described as "ambiguous". While most people are averse to both risk and ambiguity(1,2), the degree of those aversions vary substantially across individuals, such that the subjective value of the same risky or ambiguous option can be very different for different individuals. We combine functional MRI (fMRI) with an experimental economics-based method(3 )to assess the neural representation of the subjective values of risky and ambiguous options(4). This technique can be now used to study these neural representations in different populations, such as different age groups and different patient populations. In our experiment, subjects make consequential choices between two alternatives while their neural activation is tracked using fMRI. On each trial subjects choose between lotteries that vary in their monetary amount and in either the probability of winning that amount or the ambiguity level associated with winning. Our parametric design allows us to use each individual's choice behavior to estimate their attitudes towards risk and ambiguity, and thus to estimate the subjective values that each option held for them. Another important feature of the design is that the outcome of the chosen lottery is not revealed during the experiment, so that no learning can take place, and thus the ambiguous options remain ambiguous and risk attitudes are stable. Instead, at the end of the scanning session one or few trials are randomly selected and played for real money. Since subjects do not know beforehand which trials will be selected, they must treat each and every trial as if it and it alone was the one trial on which they will be paid. This design ensures that we can estimate the true subjective value of each option to each subject. We

Simply Imagining Sunshine, Lollipops and Rainbows Will Not Budge the Bias: The Role of Ambiguity in Interpretive Bias Modification.

PubMed

Clarke, Patrick J F; Nanthakumar, Shenooka; Notebaert, Lies; Holmes, Emily A; Blackwell, Simon E; Macleod, Colin

2014-01-01

Imagery-based interpretive bias modification (CBM-I) involves repeatedly imagining scenarios that are initially ambiguous before being resolved as either positive or negative in the last word/s. While the presence of such ambiguity is assumed to be important to achieve change in selective interpretation, it is also possible that the act of repeatedly imagining positive or negative events could produce such change in the absence of ambiguity. The present study sought to examine whether the ambiguity in imagery-based CBM-I is necessary to elicit change in interpretive bias, or, if the emotional content of the imagined scenarios is sufficient to produce such change. An imagery-based CBM-I task was delivered to participants in one of four conditions, where the valence of imagined scenarios were either positive or negative, and the ambiguity of the scenario was either present (until the last word/s) or the ambiguity was absent (emotional valence was evident from the start). Results indicate that only those who received scenarios in which the ambiguity was present acquired an interpretive bias consistent with the emotional valence of the scenarios, suggesting that the act of imagining positive or negative events will only influence patterns of interpretation when the emotional ambiguity is a consistent feature.

Resolving Ambiguity in Nonmonotonic Inheritance Hierarchies

DTIC Science & Technology

1991-08-01

this case, specificity cannot resolve the ambiguity w.r.t. platypus at mammal, and r 2 supports both of the assertions marked (***): that platypuses ...eoss jo~yer Figure 2: Is a platypus a mammal? Figure 3: A blue whale is an aquatic creature. eater does not defeat either the assertion that Joe is a...derived conclusion that platypuses are mammals is directly opposed by the (equally legitimate) conclusion that platypuses are not mammals. In this case

Role Ambiguity and Self-Efficacy: The Moderating Effects of Goal Orientation and Procedural Justice

ERIC Educational Resources Information Center

Li, Andrew; Bagger, Jessica

2008-01-01

The present study investigated variables that moderated the relationship between role ambiguity and self-efficacy. Results of a field study found support for the moderating role of learning goal orientation, such that the relationship between role ambiguity and self-efficacy was weaker when learning goal orientation was high. In addition, we found…

As Far As Words Go: Activities for Understanding Ambiguous Language and Humor, Revised Edition

ERIC Educational Resources Information Center

Spector, Cecile Cyrul

2009-01-01

Understanding ambiguous words, phrases, and sentences is an important part of reading well, communicating skillfully, and enjoying humor based on word play. With this seven-unit activity book--filled with creative, ready-to-use activities based on jokes and puns--students will learn how to decipher the language ambiguities they encounter inside…

Exploring the Relationship between Tolerance of Ambiguity of EFL Learners and Their Vocabulary Knowledge

ERIC Educational Resources Information Center

Basöz, Tutku

2015-01-01

Learning a new language is akin to exploring an unknown land as ambiguous situations are prevalent in language learning. Ambiguity tolerance, which can hinder or facilitate language learning, is considered as an important learning style. The purpose of the present study was to understand how tolerant/intolerant EFL learners are of foreign language…

The reciprocal dynamic model of career decision ambiguity tolerance with career indecision: A longitudinal three-wave investigation.

PubMed

Xu, Hui; Tracey, Terence J G

2017-10-01

The current study investigated the dynamic interplay of career decision ambiguity tolerance and career indecision over 3 assessment times in a sample of college students (n = 583). While the previous research has repeatedly shown an association of career decision ambiguity tolerance with career indecision, the direction of this association has not been adequately assessed with longitudinal investigation. It was hypothesized in this study that there is a reciprocal pattern of career decision ambiguity tolerance leading to subsequent career indecision and career indecision leading to subsequent career decision ambiguity tolerance. Using a cross-lagged panel design, this study found support for the reciprocal pattern that aversion to ambiguity led to increased negative affect and choice anxiety in career decision making, while negative affect and choice anxiety led to increased aversion to ambiguity. Additionally, this study revealed that aversion led to decreased readiness for career decision making and readiness for career decision making led to increased interests in new information. The key findings were discussed with respect to the theoretical and clinical implications for career counseling along with limitations and suggestions for future research. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Equivocal or ambiguous terminologies in pathology: focus of continuous quality improvement?

PubMed

Idowu, Michael O; Wiles, Austin; Wan, Wen; Wilkinson, David S; Powers, Celeste N

2013-11-01

Ambiguous terminologies introduce uncertainty into pathology reports and may be misinterpreted by clinicians. Although absolute diagnostic certainty in all cases is not attainable, nevertheless, unbridled use of equivocal or ambiguous terminologies may lead to additional, sometimes unnecessary, tests and/or procedures directly or indirectly leading to increase in health care costs, as well as patient and clinician dissatisfaction. We evaluated the degree of certainty attributed to the commonly used ambiguous terminologies ("consistent with," "compatible with," "indicative of," "favor," "suggestive of," "suspicious for," "not excluded," "cannot exclude," "not ruled out," "not definite for," "not specific for," "indeterminate," "not identified") used in pathology reports by groups of attending physicians and their respective trainees using an online survey. There is no statistical difference in the interpretation of each terminology between attending pathologists and pathology trainees. There is also no significant difference between pathology and other attending groups for majority of the terminologies. However, there are significant differences between at least 2 of the 4 attending physician categories in the following pathology terminologies: "consistent with" (overall P=0.01), "compatible with" (P=0.02), "not excluded" (P=0.008), and "cannot exclude" (P=0.01). The pairwise comparisons among the 4 specialties show that there is significant difference in the interpretation of the degree of certainty between pathology and medicine in terms of "not excluded" (P=0.007) and "cannot exclude" (P=0.03). Focused peer review or monitoring of pathology reports with ambiguous terminologies may reduce their use and represent a worthwhile and achievable goal.

Processing Deliberate Ambiguity in Newspaper Headlines: Double Grounding

ERIC Educational Resources Information Center

Brone, Geert; Coulson, Seana

2010-01-01

Two experiments investigated the processing and appreciation of double grounding, a form of intentional ambiguity often used in the construction of headlines. For example, in "Russia takes the froth off Carlsberg results," the key element, "takes the froth off," is significant both metaphorically, where it refers to the…

Creativity and Tolerance of Ambiguity: An Empirical Study

ERIC Educational Resources Information Center

Zenasni, Franck; Besancon, Maud; Lubart, Todd

2008-01-01

This study examines the relationship between creativity and tolerance of ambiguity. Participants were parents and their adolescent children. Three measures of creativity were used: a divergent thinking task, a story-writing task and self-evaluation of creative attitudes and behavior. Participants completed two self-report measures of tolerance of…

Do children exploit the Maxim of Antecedent in order to interpret ambiguous descriptions?

PubMed

Surian, L

1991-06-01

Twenty Italian six-year-olds and 20 eight-year-olds were asked to interpret eight ambiguous and eight clear definite descriptions. All ambiguous descriptions could refer to three drawings, one of which had been described by the subjects immediately before the comprehension task. In half of the trials with ambiguous messages the children's interlocutor was present while the children were describing the drawings; in the other half he was absent. In both conditions subjects showed a preference for the referents they had already described, indicating that they applied egocentrically a comprehension strategy based on the Maxim of Antecedent (Jackson & Jacobs, 1982). Children's failures to differentiate their responses in the two conditions are considered to be due to difficulties in taking account of the given-new distinction for relevant information.

Ambiguous genitalia: what prenatal genetic testing is practical?

PubMed

Adam, Margaret P; Fechner, Patricia Y; Ramsdell, Linda A; Badaru, Angela; Grady, Richard E; Pagon, Roberta A; McCauley, Elizabeth; Cheng, Edith Y; Parisi, Melissa A; Shnorhavorian, Margarett

2012-06-01

Concern for ambiguous genitalia or chromosome-phenotype discordance detected in a prenatal setting has increased over the last two decades. Practitioners faced with this prenatal finding have a variety of genetic tests available to them; however, it is unclear to what extent prenatal testing for disorders of sex development (DSD) is useful or practical. We undertook a retrospective review of the medical records of 140 individuals evaluated through the DSD clinic at Seattle Children's Hospital with birthdates from 01/01/1994 through 08/16/2011 to determine the rate of prenatal detection of ambiguous genitalia in individuals with DSD, what prenatal diagnostic workup was undertaken, and the postnatal outcome, including whether a postnatal genetic diagnosis was confirmed. Of all 140 subjects, 34 (24%) were identified prenatally. The most common postnatal diagnoses were penoscrotal hypospadias with transposition of the scrotum with no known genetic cause (24/140; 17%) and 21-hydroxylase deficiency (20/140; 14%). Apart from these, no single diagnosis comprised more than a few cases. Prenatal diagnostic testing varied widely, from no tests to multiple molecular tests with amniotic fluid hormone concentrations. In the absence of other fetal anomalies or growth retardation on ultrasound, prenatal karyotype with fluorescence in situ hybridization for the SRY gene is the most useful test when ambiguous genitalia is suspected. Further prenatal testing for Smith-Lemli-Opitz syndrome in 46,XY individuals and congenital adrenal hyperplasia in 46,XX individuals may be considered. However, targeted molecular testing for rare DSD conditions in the absence of a family history of DSD has a low yield. Copyright © 2012 Wiley Periodicals, Inc.

The indexing ambiguity in serial femtosecond crystallography (SFX) resolved using an expectation maximization algorithm.

PubMed

Liu, Haiguang; Spence, John C H

2014-11-01

Crystallographic auto-indexing algorithms provide crystal orientations and unit-cell parameters and assign Miller indices based on the geometric relations between the Bragg peaks observed in diffraction patterns. However, if the Bravais symmetry is higher than the space-group symmetry, there will be multiple indexing options that are geometrically equivalent, and hence many ways to merge diffraction intensities from protein nanocrystals. Structure factor magnitudes from full reflections are required to resolve this ambiguity but only partial reflections are available from each XFEL shot, which must be merged to obtain full reflections from these 'stills'. To resolve this chicken-and-egg problem, an expectation maximization algorithm is described that iteratively constructs a model from the intensities recorded in the diffraction patterns as the indexing ambiguity is being resolved. The reconstructed model is then used to guide the resolution of the indexing ambiguity as feedback for the next iteration. Using both simulated and experimental data collected at an X-ray laser for photosystem I in the P63 space group (which supports a merohedral twinning indexing ambiguity), the method is validated.

The ambiguous nature of epigenetic responsibility.

PubMed

Dupras, Charles; Ravitsky, Vardit

2016-08-01

Over the past decade, epigenetic studies have been providing further evidence of the molecular interplay between gene expression and its health outcomes on one hand, and the physical and social environments in which individuals are conceived, born and live on the other. As knowledge of epigenetic programming expands, a growing body of literature in social sciences and humanities is exploring the implications of this new field of study for contemporary societies. Epigenetics has been mobilised to support political claims, for instance, with regard to collective obligations to address socio-environmental determinants of health. The idea of a moral 'epigenetic responsibility' has been proposed, meaning that individuals and/or governments should be accountable for the epigenetic programming of children and/or citizens. However, these discussions have largely overlooked important biological nuances and ambiguities inherent in the field of epigenetics. In this paper, we argue that the identification and assignment of moral epigenetic responsibilities should reflect the rich diversity and complexity of epigenetic mechanisms, and not rely solely on a gross comparison between epigenetics and genetics. More specifically, we explore how further investigation of the ambiguous notions of epigenetic normality and epigenetic plasticity should play a role in shaping this emerging debate. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Interpreting ambiguous 'trace' results in Schistosoma mansoni CCA Tests: Estimating sensitivity and specificity of ambiguous results with no gold standard.

PubMed

Clements, Michelle N; Donnelly, Christl A; Fenwick, Alan; Kabatereine, Narcis B; Knowles, Sarah C L; Meité, Aboulaye; N'Goran, Eliézer K; Nalule, Yolisa; Nogaro, Sarah; Phillips, Anna E; Tukahebwa, Edridah Muheki; Fleming, Fiona M

2017-12-01

The development of new diagnostics is an important tool in the fight against disease. Latent Class Analysis (LCA) is used to estimate the sensitivity and specificity of tests in the absence of a gold standard. The main field diagnostic for Schistosoma mansoni infection, Kato-Katz (KK), is not very sensitive at low infection intensities. A point-of-care circulating cathodic antigen (CCA) test has been shown to be more sensitive than KK. However, CCA can return an ambiguous 'trace' result between 'positive' and 'negative', and much debate has focused on interpretation of traces results. We show how LCA can be extended to include ambiguous trace results and analyse S. mansoni studies from both Côte d'Ivoire (CdI) and Uganda. We compare the diagnostic performance of KK and CCA and the observed results by each test to the estimated infection prevalence in the population. Prevalence by KK was higher in CdI (13.4%) than in Uganda (6.1%), but prevalence by CCA was similar between countries, both when trace was assumed to be negative (CCAtn: 11.7% in CdI and 9.7% in Uganda) and positive (CCAtp: 20.1% in CdI and 22.5% in Uganda). The estimated sensitivity of CCA was more consistent between countries than the estimated sensitivity of KK, and estimated infection prevalence did not significantly differ between CdI (20.5%) and Uganda (19.1%). The prevalence by CCA with trace as positive did not differ significantly from estimates of infection prevalence in either country, whereas both KK and CCA with trace as negative significantly underestimated infection prevalence in both countries. Incorporation of ambiguous results into an LCA enables the effect of different treatment thresholds to be directly assessed and is applicable in many fields. Our results showed that CCA with trace as positive most accurately estimated infection prevalence.

Textbook presentations of weight: Conceptual difficulties and language ambiguities

NASA Astrophysics Data System (ADS)

Taibu, Rex; Rudge, David; Schuster, David

2015-06-01

The term "weight" has multiple related meanings in both scientific and everyday usage. Even among experts and in textbooks, weight is ambiguously defined as either the gravitational force on an object or operationally as the magnitude of the force an object exerts on a measuring scale. This poses both conceptual and language difficulties for learners, especially for accelerating objects where the scale reading is different from the gravitational force. But while the underlying physical constructs behind the two referents for the term weight (and their relation to each other) are well understood scientifically, it is unclear how the concept of weight should be introduced to students and how the language ambiguities should be dealt with. We investigated treatments of weight in a sample of twenty introductory college physics textbooks, analyzing and coding their content based on the definition adopted, how the distinct constructs were dealt with in various situations, terminologies used, and whether and how language issues were handled. Results indicate that language-related issues, such as different, inconsistent, or ambiguous uses of the terms weight, "apparent weight," and "weightlessness," were prevalent both across and within textbooks. The physics of the related constructs was not always clearly presented, particularly for accelerating bodies such as astronauts in spaceships, and the language issue was rarely addressed. Our analysis of both literature and textbooks leads us to an instructional position which focuses on the physics constructs before introducing the term weight, and which explicitly discusses the associated language issues.

On the impact of GNSS ambiguity resolution: geometry, ionosphere, time and biases

NASA Astrophysics Data System (ADS)

Khodabandeh, A.; Teunissen, P. J. G.

2018-06-01

Integer ambiguity resolution (IAR) is the key to fast and precise GNSS positioning and navigation. Next to the positioning parameters, however, there are several other types of GNSS parameters that are of importance for a range of different applications like atmospheric sounding, instrumental calibrations or time transfer. As some of these parameters may still require pseudo-range data for their estimation, their response to IAR may differ significantly. To infer the impact of ambiguity resolution on the parameters, we show how the ambiguity-resolved double-differenced phase data propagate into the GNSS parameter solutions. For that purpose, we introduce a canonical decomposition of the GNSS network model that, through its decoupled and decorrelated nature, provides direct insight into which parameters, or functions thereof, gain from IAR and which do not. Next to this qualitative analysis, we present for the GNSS estimable parameters of geometry, ionosphere, timing and instrumental biases closed-form expressions of their IAR precision gains together with supporting numerical examples.

On the impact of GNSS ambiguity resolution: geometry, ionosphere, time and biases

NASA Astrophysics Data System (ADS)

Khodabandeh, A.; Teunissen, P. J. G.

2017-11-01

Integer ambiguity resolution (IAR) is the key to fast and precise GNSS positioning and navigation. Next to the positioning parameters, however, there are several other types of GNSS parameters that are of importance for a range of different applications like atmospheric sounding, instrumental calibrations or time transfer. As some of these parameters may still require pseudo-range data for their estimation, their response to IAR may differ significantly. To infer the impact of ambiguity resolution on the parameters, we show how the ambiguity-resolved double-differenced phase data propagate into the GNSS parameter solutions. For that purpose, we introduce a canonical decomposition of the GNSS network model that, through its decoupled and decorrelated nature, provides direct insight into which parameters, or functions thereof, gain from IAR and which do not. Next to this qualitative analysis, we present for the GNSS estimable parameters of geometry, ionosphere, timing and instrumental biases closed-form expressions of their IAR precision gains together with supporting numerical examples.

Cerebellar pathology in childhood-onset vs. adult-onset essential tremor.

PubMed

Louis, Elan D; Kuo, Sheng-Han; Tate, William J; Kelly, Geoffrey C; Faust, Phyllis L

2017-10-17

Although the incidence of ET increases with advancing age, the disease may begin at any age, including childhood. The question arises as to whether childhood-onset ET cases manifest the same sets of pathological changes in the cerebellum as those whose onset is during adult life. We quantified a broad range of postmortem features (Purkinje cell [PC] counts, PC axonal torpedoes, a host of associated axonal changes [PC axonal recurrent collateral count, PC thickened axonal profile count, PC axonal branching count], heterotopic PCs, and basket cell rating) in 60 ET cases (11 childhood-onset and 49 adult-onset) and 30 controls. Compared to controls, childhood-onset ET cases had lower PC counts, higher torpedo counts, higher heterotopic PC counts, higher basket cell plexus rating, and marginally higher PC axonal recurrent collateral counts. The median PC thickened axonal profile count and median PC axonal branching count were two to five times higher in childhood-onset ET than controls, but the differences did not reach statistical significance. Childhood-onset and adult-onset ET had similar PC counts, torpedo counts, heterotopic PC counts, basket cell plexus rating, PC axonal recurrent collateral counts, PC thickened axonal profile count and PC axonal branching count. In conclusion, we found that childhood-onset and adult-onset ET shared similar pathological changes in the cerebellum. The data suggest that pathological changes we have observed in the cerebellum in ET are a part of the pathophysiological cascade of events in both forms of the disease and that both groups seem to reach the same pathological endpoints at a similar age of death. Copyright © 2017 Elsevier B.V. All rights reserved.

Anxious and angry rejection sensitivity, social withdrawal, and retribution in high and low ambiguous situations.

PubMed

Zimmer-Gembeck, Melanie J; Nesdale, Drew

2013-02-01

Rejection sensitivity (RS) is a tendency to expect, perceive, and overreact to rejection. Our objective was to examine whether anxious and angry RS have specific associations with negative social reactions, and whether responses are intensified in situations of high rejection ambiguity. In two studies, youth (N = 464 and N = 371) reported their RS and anticipated responses to social scenarios. In Study 1, all scenarios portrayed overt rejection events. In Study 2, participants were randomly assigned to conditions portraying overt or ambiguous rejection. Greater rejection expectation was associated with more negative reactions to rejection. Moreover, as expected, anxiety about rejection was uniquely associated with withdrawal, and anger about rejection was uniquely associated with retribution (i.e., reactive aggression). In the second study, RS persons responded more negatively than others to both overt and high ambiguous rejections, but retribution was intensified among participants high in rejection expectation when rejection was ambiguous, and withdrawal was intensified among participants high in anxious RS in overt rejection situations. Consistent with the revised RS model, there are different patterns of emotions, cognitions, and behaviors in response to high and low ambiguous rejection events, which are heightened in youth sensitive to rejection. © 2012, Wiley Periodicals, Inc.

Sublexical Ambiguity Effect in Reading Chinese Disyllabic Compounds

ERIC Educational Resources Information Center

Huang, Hsu-Wen; Lee, Chia-Ying; Tsai, Jie-Li; Tzeng, Ovid J.-L.

2011-01-01

For Chinese compounds, neighbors can share either both orthographic forms and meanings, or orthographic forms only. In this study, central presentation and visual half-field (VF) presentation methods were used in conjunction with ERP measures to investigate how readers solve the sublexical semantic ambiguity of the first constituent character in…

Attention capture by contour onsets and offsets: no special role for onsets.

PubMed

Watson, D G; Humphreys, G W

1995-07-01

In five experiments, we investigated the power of targets defined by the onset or offset of one of an object's parts (contour onsets and offsets) either to guide or to capture visual attention. In Experiment 1, search for a single contour onset target was compared with search for a single contour offset target against a static background of distractors; no difference was found between the efficiency with which each could be detected. In Experiment 2, onsets and offsets were compared for automatic attention capture, when both occurred simultaneously. Unlike in previous studies, the effects of overall luminance change, new-object creation, and number of onset and offset items were controlled. It was found that contour onset and offset items captured attention equally well. However, display size effects on both target types were also apparent. Such effects may have been due to competition for selection between multiple onset and offset stimuli. In Experiments 3 and 4, single onset and offset stimuli were presented simultaneously and pitted directly against one another among a background of static distractors. In Experiment 3, we examined "guided search," for a target that was formed either from an onset or from an offset among static items. In Experiment 4, the onsets and offsets were uncorrelated with the target location. Similar results occurred in both experiments: target onsets and offsets were detected more efficiently than static stimuli which needed serial search; there remained effects of display size on performance; but there was still no advantage for onsets. In Experiment 5, we examined automatic attention capture by single onset and offset stimuli presented individually among static distractors. Again, there was no advantage for onset over offset targets and a display size effect was also present. These results suggest that, both in isolation and in competition, onsets that do not form new objects neither guide nor gain automatic attention more efficiently

The ambiguity of simplicity in quantum and classical simulation

NASA Astrophysics Data System (ADS)

Aghamohammadi, Cina; Mahoney, John R.; Crutchfield, James P.

2017-04-01

A system's perceived simplicity depends on whether it is represented classically or quantally. This is not so surprising, as classical and quantum physics are descriptive frameworks built on different assumptions that capture, emphasize, and express different properties and mechanisms. What is surprising is that, as we demonstrate, simplicity is ambiguous: the relative simplicity between two systems can change sign when moving between classical and quantum descriptions. Here, we associate simplicity with small model-memory. We see that the notions of absolute physical simplicity at best form a partial, not a total, order. This suggests that appeals to principles of physical simplicity, via Ockham's Razor or to the ;elegance; of competing theories, may be fundamentally subjective. Recent rapid progress in quantum computation and quantum simulation suggest that the ambiguity of simplicity will strongly impact statistical inference and, in particular, model selection.

Ambiguity and Uncertainty in Probabilistic Inference.

DTIC Science & Technology

1983-09-01

whether one was to judge the like- lihood that the majority or minority position was true . In order to sample a wide range of values of n and p, 40...AFD-A133 418 AMBIGUITY AND UNCERTAINTY IN PROBABILISTIC INFERENCE i/i U CLRS (U) CHICGO UNIT’ IL CENTER FOR DECISION RESERCH H J EINHORN ET AL. SEP...been demonstrated experimentally (Becker & Brownson, 1964; Yates & Zukowski, 1976). On the other hand, the process by which such second-order uncertainty

Sex and Ear Differences in Spontaneous and Click-Evoked Otoacoustic Emissions in Young Adults

ERIC Educational Resources Information Center

Snihur, Adrian W. K.; Hampson, Elizabeth

2011-01-01

Effects of sex and handedness on the production of spontaneous and click-evoked otoacoustic emissions (OAEs) were explored in a non-hearing impaired population (ages 17-25 years). A sex difference in OAEs, either produced spontaneously (spontaneous OAEs or SOAEs) or in response to auditory stimuli (click-evoked OAEs or CEOAEs) has been reported in…

The impact of uncertain threat on affective bias: Individual differences in response to ambiguity.

PubMed

Neta, Maital; Cantelon, Julie; Haga, Zachary; Mahoney, Caroline R; Taylor, Holly A; Davis, F Caroline

2017-12-01

Individuals who operate under highly stressful conditions (e.g., military personnel and first responders) are often faced with the challenge of quickly interpreting ambiguous information in uncertain and threatening environments. When faced with ambiguity, it is likely adaptive to view potentially dangerous stimuli as threatening until contextual information proves otherwise. One laboratory-based paradigm that can be used to simulate uncertain threat is known as threat of shock (TOS), in which participants are told that they might receive mild but unpredictable electric shocks while performing an unrelated task. The uncertainty associated with this potential threat induces a state of emotional arousal that is not overwhelmingly stressful, but has widespread-both adaptive and maladaptive-effects on cognitive and affective function. For example, TOS is thought to enhance aversive processing and abolish positivity bias. Importantly, in certain situations (e.g., when walking home alone at night), this anxiety can promote an adaptive state of heightened vigilance and defense mobilization. In the present study, we used TOS to examine the effects of uncertain threat on valence bias, or the tendency to interpret ambiguous social cues as positive or negative. As predicted, we found that heightened emotional arousal elicited by TOS was associated with an increased tendency to interpret ambiguous cues negatively. Such negative interpretations are likely adaptive in situations in which threat detection is critical for survival and should override an individual's tendency to interpret ambiguity positively in safe contexts. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Global positioning system network analysis with phase ambiguity resolution applied to crustal deformation studies in California

NASA Technical Reports Server (NTRS)

Dong, Da-Nan; Bock, Yehuda

1989-01-01

An efficient algorithm is developed for multisession adjustment of GPS data with simultaneous orbit determination and ambiguity resolution. Application of the algorithm to the analysis of data from a five-year campaign in progress in southern and central California to monitor tectonic motions using observations by GPS satellites, demonstrates improvements in estimates of station position and satellite orbits when the phase ambiguities are resolved. Most of the phase ambiguities in the GPS network were resolved, particularly for all the baselines of geophysical interest in California.

"What Happened?" Teaching Attribution Theory through Ambiguous Prompts

ERIC Educational Resources Information Center

McArthur, John

2011-01-01

The concept of attribution, "the act of explaining why something happens or why a person acts a particular way," is typically an abstract concept. This 35-50-minute activity invites students to make a series of attributions by asking them "What happened?" in ambiguous scenes presented in class. Then, students retrospectively identify what…

A New Method for Single-Epoch Ambiguity Resolution with Indoor Pseudolite Positioning.

PubMed

Li, Xin; Zhang, Peng; Guo, Jiming; Wang, Jinling; Qiu, Weining

2017-04-21

Ambiguity resolution (AR) is crucial for high-precision indoor pseudolite positioning. Due to the existing characteristics of the pseudolite positioning system, such as the geometry structure of the stationary pseudolite which is consistently invariant, the indoor signal is easy to interrupt and the first order linear truncation error cannot be ignored, and a new AR method based on the idea of the ambiguity function method (AFM) is proposed in this paper. The proposed method is a single-epoch and nonlinear method that is especially well-suited for indoor pseudolite positioning. Considering the very low computational efficiency of conventional AFM, we adopt an improved particle swarm optimization (IPSO) algorithm to search for the best solution in the coordinate domain, and variances of a least squares adjustment is conducted to ensure the reliability of the solving ambiguity. Several experiments, including static and kinematic tests, are conducted to verify the validity of the proposed AR method. Numerical results show that the IPSO significantly improved the computational efficiency of AFM and has a more elaborate search ability compared to the conventional grid searching method. For the indoor pseudolite system, which had an initial approximate coordinate precision better than 0.2 m, the AFM exhibited good performances in both static and kinematic tests. With the corrected ambiguity gained from our proposed method, indoor pseudolite positioning can achieve centimeter-level precision using a low-cost single-frequency software receiver.

MOCCS: Clarifying DNA-binding motif ambiguity using ChIP-Seq data.

PubMed

Ozaki, Haruka; Iwasaki, Wataru

2016-08-01

As a key mechanism of gene regulation, transcription factors (TFs) bind to DNA by recognizing specific short sequence patterns that are called DNA-binding motifs. A single TF can accept ambiguity within its DNA-binding motifs, which comprise both canonical (typical) and non-canonical motifs. Clarification of such DNA-binding motif ambiguity is crucial for revealing gene regulatory networks and evaluating mutations in cis-regulatory elements. Although chromatin immunoprecipitation sequencing (ChIP-seq) now provides abundant data on the genomic sequences to which a given TF binds, existing motif discovery methods are unable to directly answer whether a given TF can bind to a specific DNA-binding motif. Here, we report a method for clarifying the DNA-binding motif ambiguity, MOCCS. Given ChIP-Seq data of any TF, MOCCS comprehensively analyzes and describes every k-mer to which that TF binds. Analysis of simulated datasets revealed that MOCCS is applicable to various ChIP-Seq datasets, requiring only a few minutes per dataset. Application to the ENCODE ChIP-Seq datasets proved that MOCCS directly evaluates whether a given TF binds to each DNA-binding motif, even if known position weight matrix models do not provide sufficient information on DNA-binding motif ambiguity. Furthermore, users are not required to provide numerous parameters or background genomic sequence models that are typically unavailable. MOCCS is implemented in Perl and R and is freely available via https://github.com/yuifu/moccs. By complementing existing motif-discovery software, MOCCS will contribute to the basic understanding of how the genome controls diverse cellular processes via DNA-protein interactions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evolution of the Toarcian (Early Jurassic) carbon-cycle and global climatic controls on local sedimentary processes (Cardigan Bay Basin, UK)

NASA Astrophysics Data System (ADS)

Xu, Weimu; Ruhl, Micha; Jenkyns, Hugh C.; Leng, Melanie J.; Huggett, Jennifer M.; Minisini, Daniel; Ullmann, Clemens V.; Riding, James B.; Weijers, Johan W. H.; Storm, Marisa S.; Percival, Lawrence M. E.; Tosca, Nicholas J.; Idiz, Erdem F.; Tegelaar, Erik W.; Hesselbo, Stephen P.

2018-02-01

The late Early Jurassic Toarcian Stage represents the warmest interval of the Jurassic Period, with an abrupt rise in global temperatures of up to ∼7 °C in mid-latitudes at the onset of the early Toarcian Oceanic Anoxic Event (T-OAE; ∼183 Ma). The T-OAE, which has been extensively studied in marine and continental successions from both hemispheres, was marked by the widespread expansion of anoxic and euxinic waters, geographically extensive deposition of organic-rich black shales, and climatic and environmental perturbations. Climatic and environmental processes following the T-OAE are, however, poorly known, largely due to a lack of study of stratigraphically well-constrained and complete sedimentary archives. Here, we present integrated geochemical and physical proxy data (high-resolution carbon-isotope data (δ13 C), bulk and molecular organic geochemistry, inorganic petrology, mineral characterisation, and major- and trace-element concentrations) from the biostratigraphically complete and expanded entire Toarcian succession in the Llanbedr (Mochras Farm) Borehole, Cardigan Bay Basin, Wales, UK. With these data, we (1) construct the first high-resolution biostratigraphically calibrated chemostratigraphic reference record for nearly the complete Toarcian Stage, (2) establish palaeoceanographic and depositional conditions in the Cardigan Bay Basin, (3) show that the T-OAE in the hemipelagic Cardigan Bay Basin was marked by the occurrence of gravity-flow deposits that were likely linked to globally enhanced sediment fluxes to continental margins and deeper marine (shelf) basins, and (4) explore how early Toarcian (tenuicostatum and serpentinum zones) siderite formation in the Cardigan Bay Basin may have been linked to low global oceanic sulphate concentrations and elevated supply of iron (Fe) from the hinterland, in response to climatically induced changes in hydrological cycling, global weathering rates and large-scale sulphide and evaporite deposition.

Disambiguating ambiguous biomedical terms in biomedical narrative text: an unsupervised method.

PubMed

Liu, H; Lussier, Y A; Friedman, C

2001-08-01

With the growing use of Natural Language Processing (NLP) techniques for information extraction and concept indexing in the biomedical domain, a method that quickly and efficiently assigns the correct sense of an ambiguous biomedical term in a given context is needed concurrently. The current status of word sense disambiguation (WSD) in the biomedical domain is that handcrafted rules are used based on contextual material. The disadvantages of this approach are (i) generating WSD rules manually is a time-consuming and tedious task, (ii) maintenance of rule sets becomes increasingly difficult over time, and (iii) handcrafted rules are often incomplete and perform poorly in new domains comprised of specialized vocabularies and different genres of text. This paper presents a two-phase unsupervised method to build a WSD classifier for an ambiguous biomedical term W. The first phase automatically creates a sense-tagged corpus for W, and the second phase derives a classifier for W using the derived sense-tagged corpus as a training set. A formative experiment was performed, which demonstrated that classifiers trained on the derived sense-tagged corpora achieved an overall accuracy of about 97%, with greater than 90% accuracy for each individual ambiguous term.

The Development of Preschoolers' Appreciation of Communicative Ambiguity

ERIC Educational Resources Information Center

Nilsen, Elizabeth S.; Graham, Susan A.

2012-01-01

Using a longitudinal design, preschoolers' appreciation of a listener's knowledge of the location of a hidden sticker after the listener was provided with an ambiguous or unambiguous description was assessed. Preschoolers (N = 34) were tested at 3 time points, each 6 months apart (4, 4 1/2, and 5 years). Eye gaze measures demonstrated that…

Ambiguity and uncertainty tolerance, need for cognition, and their association with stress. A study among Italian practicing physicians.

PubMed

Iannello, Paola; Mottini, Anna; Tirelli, Simone; Riva, Silvia; Antonietti, Alessandro

2017-01-01

Medical practice is inherently ambiguous and uncertain. The physicians' ability to tolerate ambiguity and uncertainty has been proved to have a great impact on clinical practice. The primary aim of the present study was to test the hypothesis that higher degree of physicians' ambiguity and uncertainty intolerance and higher need for cognitive closure will predict higher work stress. Two hundred and twelve physicians (mean age = 42.94 years; SD = 10.72) from different medical specialties with different levels of expertise were administered a set of questionnaires measuring perceived levels of work-related stress, individual ability to tolerate ambiguity, stress deriving from uncertainty, and personal need for cognitive closure. A linear regression analysis was performed to examine which variables predict the perceived level of stress. The regression model was statistically significant [R 2  = .32; F(10,206) = 8.78, p ≤ .001], thus showing that, after controlling for gender and medical specialty, ambiguity and uncertainty tolerance, decisiveness (a dimension included in need for closure), and the years of practice were significant predictors of perceived work-related stress. Findings from the present study have some implications for medical education. Given the great impact that the individual ability to tolerate ambiguity and uncertainty has on the physicians' level of perceived work-related stress, it would be worth paying particular attention to such a skill in medical education settings. It would be crucial to introduce or to empower educational tools and strategies that could increase medical students' ability to tolerate ambiguity and uncertainty. JSQ: Job stress questionnaire; NFCS: Need for cognitive closure scale; PRU: Physicians' reactions to uncertainty; TFA: Tolerance for ambiguity.

Speech rhythm facilitates syntactic ambiguity resolution: ERP evidence.

PubMed

Roncaglia-Denissen, Maria Paula; Schmidt-Kassow, Maren; Kotz, Sonja A

2013-01-01

In the current event-related potential (ERP) study, we investigated how speech rhythm impacts speech segmentation and facilitates the resolution of syntactic ambiguities in auditory sentence processing. Participants listened to syntactically ambiguous German subject- and object-first sentences that were spoken with either regular or irregular speech rhythm. Rhythmicity was established by a constant metric pattern of three unstressed syllables between two stressed ones that created rhythmic groups of constant size. Accuracy rates in a comprehension task revealed that participants understood rhythmically regular sentences better than rhythmically irregular ones. Furthermore, the mean amplitude of the P600 component was reduced in response to object-first sentences only when embedded in rhythmically regular but not rhythmically irregular context. This P600 reduction indicates facilitated processing of sentence structure possibly due to a decrease in processing costs for the less-preferred structure (object-first). Our data suggest an early and continuous use of rhythm by the syntactic parser and support language processing models assuming an interactive and incremental use of linguistic information during language processing.

Speech Rhythm Facilitates Syntactic Ambiguity Resolution: ERP Evidence

PubMed Central

Roncaglia-Denissen, Maria Paula; Schmidt-Kassow, Maren; Kotz, Sonja A.

2013-01-01

In the current event-related potential (ERP) study, we investigated how speech rhythm impacts speech segmentation and facilitates the resolution of syntactic ambiguities in auditory sentence processing. Participants listened to syntactically ambiguous German subject- and object-first sentences that were spoken with either regular or irregular speech rhythm. Rhythmicity was established by a constant metric pattern of three unstressed syllables between two stressed ones that created rhythmic groups of constant size. Accuracy rates in a comprehension task revealed that participants understood rhythmically regular sentences better than rhythmically irregular ones. Furthermore, the mean amplitude of the P600 component was reduced in response to object-first sentences only when embedded in rhythmically regular but not rhythmically irregular context. This P600 reduction indicates facilitated processing of sentence structure possibly due to a decrease in processing costs for the less-preferred structure (object-first). Our data suggest an early and continuous use of rhythm by the syntactic parser and support language processing models assuming an interactive and incremental use of linguistic information during language processing. PMID:23409109

Implementation ambiguity: The fifth element long lost in uncertainty budgets for land biogeochemical modeling

NASA Astrophysics Data System (ADS)

Tang, J.; Riley, W. J.

2015-12-01

Previous studies have identified four major sources of predictive uncertainty in modeling land biogeochemical (BGC) processes: (1) imperfect initial conditions (e.g., assumption of preindustrial equilibrium); (2) imperfect boundary conditions (e.g., climate forcing data); (3) parameterization (type I equifinality); and (4) model structure (type II equifinality). As if that were not enough to cause substantial sleep loss in modelers, we propose here a fifth element of uncertainty that results from implementation ambiguity that occurs when the model's mathematical description is translated into computational code. We demonstrate the implementation ambiguity using the example of nitrogen down regulation, a necessary process in modeling carbon-climate feedbacks. We show that, depending on common land BGC model interpretations of the governing equations for mineral nitrogen, there are three different implementations of nitrogen down regulation. We coded these three implementations in the ACME land model (ALM), and explored how they lead to different preindustrial and contemporary land biogeochemical states and fluxes. We also show how this implementation ambiguity can lead to different carbon-climate feedback estimates across the RCP scenarios. We conclude by suggesting how to avoid such implementation ambiguity in ESM BGC models.

Source preference and ambiguity aversion: models and evidence from behavioral and neuroimaging experiments.

PubMed

Chew, Soo Hong; Li, King King; Chark, Robin; Zhong, Songfa

2008-01-01

This experimental economics study using brain imaging techniques investigates the risk-ambiguity distinction in relation to the source preference hypothesis (Fox & Tversky, 1995) in which identically distributed risks arising from different sources of uncertainty may engender distinct preferences for the same decision maker, contrary to classical economic thinking. The use of brain imaging enables sharper testing of the implications of different models of decision-making including Chew and Sagi's (2008) axiomatization of source preference. Using fMRI, brain activations were observed when subjects make 48 sequential binary choices among even-chance lotteries based on whether the trailing digits of a number of stock prices at market closing would be odd or even. Subsequently, subjects rate familiarity of the stock symbols. When contrasting brain activation from more familiar sources with those from less familiar ones, regions appearing to be more active include the putamen, medial frontal cortex, and superior temporal gyrus. ROI analysis showed that the activation patterns in the familiar-unfamiliar and unfamiliar-familiar contrasts are similar to those in the risk-ambiguity and ambiguity-risk contrasts reported by Hsu et al. (2005). This supports the conjecture that the risk-ambiguity distinction can be subsumed by the source preference hypothesis. Our odd-even design has the advantage of inducing the same "unambiguous" probability of half for each subject in each binary comparison. Our finding supports the implications of the Chew-Sagi model and rejects models based on global probabilistic sophistication, including rank-dependent models derived from non-additive probabilities, e.g., Choquet expected utility and cumulative prospect theory, as well as those based on multiple priors, e.g., alpha-maxmin. The finding in Hsu et al. (2005) that orbitofrontal cortex lesion patients display neither ambiguity aversion nor risk aversion offers further support to the Chew

Ambiguity and variability of database and software names in bioinformatics.

PubMed

Duck, Geraint; Kovacevic, Aleksandar; Robertson, David L; Stevens, Robert; Nenadic, Goran

2015-01-01

There are numerous options available to achieve various tasks in bioinformatics, but until recently, there were no tools that could systematically identify mentions of databases and tools within the literature. In this paper we explore the variability and ambiguity of database and software name mentions and compare dictionary and machine learning approaches to their identification. Through the development and analysis of a corpus of 60 full-text documents manually annotated at the mention level, we report high variability and ambiguity in database and software mentions. On a test set of 25 full-text documents, a baseline dictionary look-up achieved an F-score of 46 %, highlighting not only variability and ambiguity but also the extensive number of new resources introduced. A machine learning approach achieved an F-score of 63 % (with precision of 74 %) and 70 % (with precision of 83 %) for strict and lenient matching respectively. We characterise the issues with various mention types and propose potential ways of capturing additional database and software mentions in the literature. Our analyses show that identification of mentions of databases and tools is a challenging task that cannot be achieved by relying on current manually-curated resource repositories. Although machine learning shows improvement and promise (primarily in precision), more contextual information needs to be taken into account to achieve a good degree of accuracy.

Ambiguities in the retrieval of rain rates from radar returns at attenuating wavelengths

NASA Technical Reports Server (NTRS)

Haddad, Z. S.; Im, E.; Durden, S. L.

1993-01-01

It is well-known that there are significant deterministic ambiguities inherent in trying to determine the particular rain rate profile which produced some given sequence of air- or space-borne radar echo powers at a single attenuating frequency. We quantify these ambiguities mathematically, and examine their effect on various proposed rain-rate profile retrieval algorithms. When the given data consist of a single radiometer measurement together with a single-look-angle single-frequency set of range-compressed echo powers, we show that several substantially different rain profiles can realistically be considered solutions. On the other hand, if the data consist of a single-look-angle two-frequency set of echo powers, the inversion problem generically has a unique solution. We note that traditional 'back-of-the-envelope' arguments can be quite misleading in assessing the extent of the ambiguity, even in the simplest cases.

Ambiguity Detection in Adolescents with Asperger Syndrome: Is Central Coherence or Theory of Mind Impaired?

ERIC Educational Resources Information Center

Le Sourn-Bissaoui, Sandrine; Caillies, Stephanie; Gierski, Fabien; Motte, Jacques

2011-01-01

The aim of this study was to investigate the role of central coherence skills and theory of mind competences in ambiguity detection in adolescents with Asperger syndrome (AS). We sought to pinpoint the level at which AS individuals experience difficulty detecting semantic ambiguity and identify the factors that account for their problems. We…

Optimal combination of illusory and luminance-defined 3-D surfaces: A role for ambiguity.

PubMed

Hartle, Brittney; Wilcox, Laurie M; Murray, Richard F

2018-04-01

The shape of the illusory surface in stereoscopic Kanizsa figures is determined by the interpolation of depth from the luminance edges of adjacent inducing elements. Despite ambiguity in the position of illusory boundaries, observers reliably perceive a coherent three-dimensional (3-D) surface. However, this ambiguity may contribute additional uncertainty to the depth percept beyond what is expected from measurement noise alone. We evaluated the intrinsic ambiguity of illusory boundaries by using a cue-combination paradigm to measure the reliability of depth percepts elicited by stereoscopic illusory surfaces. We assessed the accuracy and precision of depth percepts using 3-D Kanizsa figures relative to luminance-defined surfaces. The location of the surface peak was defined by illusory boundaries, luminance-defined edges, or both. Accuracy and precision were assessed using a depth-discrimination paradigm. A maximum likelihood linear cue combination model was used to evaluate the relative contribution of illusory and luminance-defined signals to the perceived depth of the combined surface. Our analysis showed that the standard deviation of depth estimates was consistent with an optimal cue combination model, but the points of subjective equality indicated that observers consistently underweighted the contribution of illusory boundaries. This systematic underweighting may reflect a combination rule that attributes additional intrinsic ambiguity to the location of the illusory boundary. Although previous studies show that illusory and luminance-defined contours share many perceptual similarities, our model suggests that ambiguity plays a larger role in the perceptual representation of illusory contours than of luminance-defined contours.

Children's Use of Gesture to Resolve Lexical Ambiguity

ERIC Educational Resources Information Center

Kidd, Evan; Holler, Judith

2009-01-01

We report on a study investigating 3-5-year-old children's use of gesture to resolve lexical ambiguity. Children were told three short stories that contained two homonym senses; for example, "bat" (flying mammal) and "bat" (sports equipment). They were then asked to re-tell these stories to a second experimenter. The data were coded for the means…

Target Tracking Using SePDAF under Ambiguous Angles for Distributed Array Radar.

PubMed

Long, Teng; Zhang, Honggang; Zeng, Tao; Chen, Xinliang; Liu, Quanhua; Zheng, Le

2016-09-09

Distributed array radar can improve radar detection capability and measurement accuracy. However, it will suffer cyclic ambiguity in its angle estimates according to the spatial Nyquist sampling theorem since the large sparse array is undersampling. Consequently, the state estimation accuracy and track validity probability degrades when the ambiguous angles are directly used for target tracking. This paper proposes a second probability data association filter (SePDAF)-based tracking method for distributed array radar. Firstly, the target motion model and radar measurement model is built. Secondly, the fusion result of each radar's estimation is employed to the extended Kalman filter (EKF) to finish the first filtering. Thirdly, taking this result as prior knowledge, and associating with the array-processed ambiguous angles, the SePDAF is applied to accomplish the second filtering, and then achieving a high accuracy and stable trajectory with relatively low computational complexity. Moreover, the azimuth filtering accuracy will be promoted dramatically and the position filtering accuracy will also improve. Finally, simulations illustrate the effectiveness of the proposed method.

Target Tracking Using SePDAF under Ambiguous Angles for Distributed Array Radar

PubMed Central

Long, Teng; Zhang, Honggang; Zeng, Tao; Chen, Xinliang; Liu, Quanhua; Zheng, Le

2016-01-01

Distributed array radar can improve radar detection capability and measurement accuracy. However, it will suffer cyclic ambiguity in its angle estimates according to the spatial Nyquist sampling theorem since the large sparse array is undersampling. Consequently, the state estimation accuracy and track validity probability degrades when the ambiguous angles are directly used for target tracking. This paper proposes a second probability data association filter (SePDAF)-based tracking method for distributed array radar. Firstly, the target motion model and radar measurement model is built. Secondly, the fusion result of each radar’s estimation is employed to the extended Kalman filter (EKF) to finish the first filtering. Thirdly, taking this result as prior knowledge, and associating with the array-processed ambiguous angles, the SePDAF is applied to accomplish the second filtering, and then achieving a high accuracy and stable trajectory with relatively low computational complexity. Moreover, the azimuth filtering accuracy will be promoted dramatically and the position filtering accuracy will also improve. Finally, simulations illustrate the effectiveness of the proposed method. PMID:27618058

Analytical Review of Contemporary Fatwas in Resolving Biomedical Issues Over Gender Ambiguity.

PubMed

Zabidi, Taqwa

2018-04-21

Issues of gender ambiguity have been discussed over time from both Islamic and medical perspectives. In Islam, these issues are typically considered in the context of khunūthah (literally translated as hermaphroditism). While biomedical studies have appeared to provide a large amount of information on abnormal human biological development, i.e. Disorders of Sex Development (DSDs). However, the connection between these two fields has been given little attention. This research aims to determine the Islamic underpinnings through the fatwa around the globe. Thus, institutional fatwa organisations among Sunni schools of thought at the international, regional and national levels are observed. The fatwas regarding the management of individuals with gender ambiguity, not specifically on DSDs, are chosen and presented accordingly. Based on the findings, the sporadic fatwas from different parts of the world delineate the issue of sex ambiguity and seem to be able to provide general guidelines for management of Muslim patients with DSDs. Three common aspects have been discussed including the methodology of gender assignment, the decision-making process and the surgical and hormonal treatments.

Mixed and Ambiguous Endometrial Carcinomas: A Heterogenous Group of Tumors With Different Clinicopathologic and Molecular Genetic Features.

PubMed

Espinosa, Iñigo; D'Angelo, Emanuela; Palacios, José; Prat, Jaime

2016-07-01

Besides endometrioid, serous, and clear cell carcinomas, there are endometrial carcinomas exhibiting mixed and ambiguous morphologic features. We have analyzed the immunophenotype (p53, p16, β-catenin, ER, HNF-1B, MLH1, and Ki-67) and mutational status (PTEN, KRAS, PIK3CA, and POLE) of 7 mixed carcinomas and 13 ambiguous carcinomas, all of them classified initially as mixed carcinomas. Only 2 of the 7 (28%) mixed carcinomas showed different immunophenotypes in different components. All but 2 tumors (5/7, 71%) overexpressed p53 and p16 and were negative for ER. Both carcinomas (2/7, 28%) showed a prominent micropapillary component that resembled an ovarian low-grade serous carcinoma and merged with villoglandular endometrioid carcinoma. The ambiguous carcinomas exhibited glandular architecture, high nuclear grade, and overlapping features of endometrioid and serous carcinomas. All tumors overexpressed p53 and p16, and the majority of cases (12/13, 92%) were negative for ER. KRAS mutations were identified in 3 of 7 (42%) mixed carcinomas, including the 2 cases with a "low-grade" serous-like component. PIK3CA mutations occurred in 2 (2/13, 15%) ambiguous carcinomas and PTEN mutations in 1 (1/7, 14%) mixed and 1 (1/13, 8%) ambiguous carcinoma. POLE exonuclease domain mutations were encountered in a case of mixed undifferentiated and well-differentiated (dedifferentiated) carcinoma. Two of the 7 (29%) mixed endometrial carcinomas and 5 of the 13 (38%) ambiguous carcinomas had extended beyond the pelvis (stages III and IV). Two of the 7 (29%) patients with mixed endometrial carcinoma and 6 of 12 (50%) patients with ambiguous endometrial carcinoma were alive with disease or had died of tumor. Our results show that, biologically, many so-called mixed carcinomas represent serous carcinomas with ambiguous morphology. Our series include 2 true mixed endometrial carcinomas with a "low-grade serous"-like component, microcystic, elongated, or fragmented features, KRAS mutations

An Efficient Implementation of Fixed Failure-Rate Ratio Test for GNSS Ambiguity Resolution.

PubMed

Hou, Yanqing; Verhagen, Sandra; Wu, Jie

2016-06-23

Ambiguity Resolution (AR) plays a vital role in precise GNSS positioning. Correctly-fixed integer ambiguities can significantly improve the positioning solution, while incorrectly-fixed integer ambiguities can bring large positioning errors and, therefore, should be avoided. The ratio test is an extensively used test to validate the fixed integer ambiguities. To choose proper critical values of the ratio test, the Fixed Failure-rate Ratio Test (FFRT) has been proposed, which generates critical values according to user-defined tolerable failure rates. This contribution provides easy-to-implement fitting functions to calculate the critical values. With a massive Monte Carlo simulation, the functions for many different tolerable failure rates are provided, which enriches the choices of critical values for users. Moreover, the fitting functions for the fix rate are also provided, which for the first time allows users to evaluate the conditional success rate, i.e., the success rate once the integer candidates are accepted by FFRT. The superiority of FFRT over the traditional ratio test regarding controlling the failure rate and preventing unnecessary false alarms is shown by a simulation and a real data experiment. In the real data experiment with a baseline of 182.7 km, FFRT achieved much higher fix rates (up to 30% higher) and the same level of positioning accuracy from fixed solutions as compared to the traditional critical value.

King v. Burwell: Desperately Seeking Ambiguity in Clear Statutory Text.

PubMed

Adler, Jonathan H; Cannon, Michael F

2015-06-01

Does the Patient Protection and Affordable Care Act (ACA) of 2010 authorize tax credits within the thirty-six states that failed to establish health insurance exchanges? That is the question presented in Pruitt v. Burwell, Halbig v. Burwell, King v. Burwell, and Indiana v. IRS. The plaintiffs argue that the statute is clear and forecloses any possibility of tax credits in federal exchanges. The government argues that the statute plainly authorizes tax credits in federal exchanges, or is at least ambiguous on the question. Mere disagreement is not evidence of ambiguity. Reaching the truth requires wading deep into each side's arguments. Whether the relevant text is viewed in isolation or in its full statutory context, the ACA authorizes tax credits only in exchanges established by the states. Copyright © 2015 by Duke University Press.

Executive function and intelligence in the resolution of temporary syntactic ambiguity: an individual differences investigation.

PubMed

Engelhardt, Paul E; Nigg, Joel T; Ferreira, Fernanda

2017-07-01

In the current study, we examined the role of intelligence and executive functions in the resolution of temporary syntactic ambiguity using an individual differences approach. Data were collected from 174 adolescents and adults who completed a battery of cognitive tests as well as a sentence comprehension task. The critical items for the comprehension task consisted of object/subject garden paths (e.g., While Anna dressed the baby that was small and cute played in the crib), and participants answered a comprehension question (e.g., Did Anna dress the baby?) following each one. Previous studies have shown that garden-path misinterpretations tend to persist into final interpretations. Results showed that both intelligence and processing speed interacted with ambiguity. Individuals with higher intelligence and faster processing were more likely to answer the comprehension questions correctly and, specifically, following ambiguous as opposed to unambiguous sentences. Inhibition produced a marginal effect, but the variance in inhibition was largely shared with intelligence. Conclusions focus on the role of individual differences in cognitive ability and their impact on syntactic ambiguity resolution.

[Effects of punctuation on the processing of syntactically ambiguous Japanese sentences with a semantic bias].

PubMed

Niikuni, Keiyu; Muramoto, Toshiaki

2014-06-01

This study explored the effects of a comma on the processing of structurally ambiguous Japanese sentences with a semantic bias. A previous study has shown that a comma which is incompatible with an ambiguous sentence's semantic bias affects the processing of the sentence, but the effects of a comma that is compatible with the bias are unclear. In the present study, we examined the role of a comma compatible with the sentence's semantic bias using the self-paced reading method, which enabled us to determine the reading times for the region of the sentence where readers would be expected to solve the ambiguity using semantic information (the "target region"). The results show that a comma significantly increases the reading time of the punctuated word but decreases the reading time in the target region. We concluded that even if the semantic information provided might be sufficient for disambiguation, the insertion of a comma would affect the processing cost of the ambiguity, indicating that readers use both the comma and semantic information in parallel for sentence processing.

Executive function and intelligence in the resolution of temporary syntactic ambiguity: an individual differences investigation

PubMed Central

Engelhardt, Paul E.; Nigg, Joel T.; Ferreira, Fernanda

2016-01-01

In the current study, we examined the role of intelligence and executive functions in the resolution of temporary syntactic ambiguity using an individual differences approach. Data were collected from 174 adolescents and adults who completed a battery of cognitive tests as well as a sentence comprehension task. The critical items for the comprehension task consisted of object/subject garden paths (e.g., While Anna dressed the baby that was small and cute played in the crib), and participants answered a comprehension question (e.g., Did Anna dress the baby?) following each one. Previous studies have shown that garden-path misinterpretations tend to persist into final interpretations. Results showed that both intelligence and processing speed interacted with ambiguity. Individuals with higher intelligence and faster processing were more likely to answer the comprehension questions correctly and, specifically, following ambiguous as opposed to unambiguous sentences. Inhibition produced a marginal effect, but the variance in inhibition was largely shared with intelligence. Conclusions focus on the role of individual differences in cognitive ability and their impact on syntactic ambiguity resolution. PMID:27150661

Aversion to Ambiguity Regarding Medical Tests and Treatments: Measurement, Prevalence, and Relationship to Sociodemographic Factors

PubMed Central

HAN, PAUL K. J.; REEVE, BRYCE B.; MOSER, RICHARD P.; KLEIN, WILLIAM M. P.

2014-01-01

Aversion to “ambiguity”—uncertainty about the reliability, credibility, or adequacy of risk-related information—is an important problem that may influence judgments and decisions about medical interventions. Ambiguity aversion (AA) varies among individuals, however, and has been understudied in the health domain. To explore this phenomenon further, we developed a new theory-based measure of aversion to ambiguity regarding medical tests and treatments, and examined the prevalence and association of AA with sociodemographic factors. The “AA-Med” scale was developed using a large survey sample of the U.S. public (n = 4,398), and scale psychometric properties and the population distribution of AA were evaluated. The scale demonstrated acceptable reliability (α = .73) and validity as ascertained by association with respondents’ interest in a hypothetical ambiguous cancer screening test. Ambiguity aversion (AA) was associated with older age, non-White race, lower education and income, and female sex. The AA-Med scale is a promising new measure, and AA is associated with several sociodemographic factors. We discuss implications of these findings and potential applications of the scale for future research. PMID:19731127

Pragmatic Failure and Referential Ambiguity when Attorneys Ask Child Witnesses "Do You Know/Remember" Questions.

PubMed

Evans, Angela D; Stolzenberg, Stacia N; Lyon, Thomas D

2017-05-01

"Do you know" and "Do you remember" (DYK/R) questions explicitly ask whether one knows or remembers some information while implicitly asking for that information. This study examined how 104 4- to 9-year-old children testifying in child sexual abuse cases responded to DYK/R wh- and yes/no questions. When asked DYK/R questions containing an implicit wh- question requesting information, children often provided unelaborated "Yes" responses. Attorneys' follow-up questions suggested that children usually misunderstood the pragmatics of the questions. When DYK/R questions contained an implicit yes/no question, unelaborated "Yes" or "No" responses could be responding to the explicit or the implicit questions resulting in referentially ambiguous responses. Children often provided referentially ambiguous responses and attorneys usually failed to disambiguate children's answers. Although pragmatic failure following DYK/R wh- questions decreased with age, the likelihood of referential ambiguity following DYK/R yes/no questions did not. The results highlight the risks of serious miscommunications caused by pragmatic misunderstanding and referential ambiguity when children testify.

Ambiguity and uncertainty tolerance, need for cognition, and their association with stress. A study among Italian practicing physicians

PubMed Central

Iannello, Paola; Mottini, Anna; Tirelli, Simone; Riva, Silvia; Antonietti, Alessandro

2017-01-01

ABSTRACT Medical practice is inherently ambiguous and uncertain. The physicians’ ability to tolerate ambiguity and uncertainty has been proved to have a great impact on clinical practice. The primary aim of the present study was to test the hypothesis that higher degree of physicians’ ambiguity and uncertainty intolerance and higher need for cognitive closure will predict higher work stress. Two hundred and twelve physicians (mean age = 42.94 years; SD = 10.72) from different medical specialties with different levels of expertise were administered a set of questionnaires measuring perceived levels of work-related stress, individual ability to tolerate ambiguity, stress deriving from uncertainty, and personal need for cognitive closure. A linear regression analysis was performed to examine which variables predict the perceived level of stress. The regression model was statistically significant [R2 = .32; F(10,206) = 8.78, p ≤ .001], thus showing that, after controlling for gender and medical specialty, ambiguity and uncertainty tolerance, decisiveness (a dimension included in need for closure), and the years of practice were significant predictors of perceived work-related stress. Findings from the present study have some implications for medical education. Given the great impact that the individual ability to tolerate ambiguity and uncertainty has on the physicians’ level of perceived work-related stress, it would be worth paying particular attention to such a skill in medical education settings. It would be crucial to introduce or to empower educational tools and strategies that could increase medical students’ ability to tolerate ambiguity and uncertainty. Abbreviations: JSQ: Job stress questionnaire; NFCS: Need for cognitive closure scale; PRU: Physicians’ reactions to uncertainty; TFA: Tolerance for ambiguity PMID:28178917

Selective impairment of decision making under ambiguity in alexithymia.

PubMed

Zhang, Lei; Wang, Xue; Zhu, Yu; Li, Hongchen; Zhu, Chunyan; Yu, Fengqiong; Wang, Kai

2017-11-28

Alexithymia is characterised by difficulties identifying and describing emotions. Few studies have investigated how alexithymia influences decision-making under different conditions (ambiguity and risk). This study aimed to examine whether alexithymia contributes to impairment in decision-making. This study included 42 participants with high scores in the Chinese version of Toronto Alexithymia Scale (alexithymia group), and 44 matched subjects with low scores (control group). Decision-making was measured using the Iowa Gambling Task (IGT) and the Game of Dice Task (GDT). The main findings of this study revealed selective deficits in IGT performance for the alexithymia group, while GDT performance was unimpaired when compared with the control group. In IGT, total netscores were lower for the alexithymia group compared to the control group, particularly with regard to block 5. Moreover, the alexithymia individuals selected significantly more adverse cards than the controls, indicating significant decision-making impairments. Alexithymia selectively influences decision-making under ambiguity.

Children's understanding of ambiguous idioms and conversational perspective-taking.

PubMed

Le Sourn-Bissaoui, Sandrine; Caillies, Stéphanie; Bernard, Stéphane; Deleau, Michel; Brulé, Lauriane

2012-08-01

The aim of this study was to test the hypothesis that conversational perspective-taking is a determinant of unfamiliar ambiguous idiom comprehension. We investigated two types of ambiguous idiom, decomposable and nondecomposable expressions, which differ in the degree to which the literal meanings of the individual words contribute to the overall idiomatic meaning. We designed an experiment to assess the relationship between the acquisition of figurative comprehension and conversational perspective-taking. Our sample of children aged 5-7 years performed three conversational perspective-taking tasks (language acts, shared/unshared information, and conversational maxims). They then listened to decomposable and nondecomposable idiomatic expressions presented in context before performing a multiple-choice task (figurative, literal, and contextual responses). Results indicated that decomposable idiom comprehension was predicted by conversational perspective-taking scores and language skills, whereas nondecomposable idiom comprehension was predicted solely by language skills. We discuss our findings with respect to verbal and pragmatic skills. Copyright © 2012 Elsevier Inc. All rights reserved.

In the Face of Uncertainty: A Twin Study of Ambiguous Information, Anxiety and Depression in Children

ERIC Educational Resources Information Center

Eley, Thalia C.; Gregory, Alice M.; Lau, Jennifer Y. F.; McGuffin, Peter; Napolitano, Maria; Rijsdijk, Fruhling V.; Clark, David M.

2008-01-01

Anxiety and depression share genetic influences, and have been associated with similar cognitive biases. Psychological theories of anxiety and depression highlight threat interpretations of ambiguity. Little is known about whether genes influence cognitive style, or its links to symptoms. We assessed ambiguous word and scenario interpretations,…

Disease evolution in late-onset and early-onset systemic lupus erythematosus.

PubMed

Aljohani, R; Gladman, D D; Su, J; Urowitz, M B

2017-10-01

Objective The objective of this study was to compare clinical features, disease activity, and outcome in late-onset versus early-onset systemic lupus erythematosus (SLE) over 5 years of follow up Method Patients with SLE since 1970 were followed prospectively according to standard protocol and tracked on a computerized database. Patients entering the cohort within one year of diagnosis constitute the inception cohort. Patients with late-onset (age at diagnosis ≥50) disease were identified and matched 1:2 based on gender and first clinic visit (±5) years with patients with early-onset disease (age at diagnosis 18-40 years). Results A total of 86 patients with late-onset disease (84.9% female, 81.4% Caucasian, mean age at SLE diagnosis ± SD 58.05 ± 7.30) and 169 patients with early-onset disease (86.4% female, 71% Caucasian, mean age at SLE diagnosis ± SD 27.80 ± 5.90) were identified. At enrollment, late-onset SLE patients had a lower total number of American College of Rheumatology (ACR) criteria, with less renal and neurologic manifestations. Mean SLE Disease Activity Index 2000 (SLEDAI-2K) scores were lower in late-onset SLE, especially renal features and anti-dsDNA positivity. Over 5 years, mean SLEDAI-2K scores decreased in both groups, while mean Systemic Lupus International Collaborating Clinics/ACR Damage Index (SDI) scores increased more significantly in the late-onset group; they developed more cardiovascular, renal, and ocular damage, and had higher prevalence of cardiovascular risk factors. Conclusion Although the late-onset SLE group had a milder presentation and less active disease, with the evolution of disease, they developed more organ damage likely as a consequence of cardiovascular risk factors and aging.

Housing conditions affect rat responses to two types of ambiguity in a reward–reward discrimination cognitive bias task

PubMed Central

Parker, Richard M.A.; Paul, Elizabeth S.; Burman, Oliver H.P.; Browne, William J.; Mendl, Michael

2014-01-01

Decision-making under ambiguity in cognitive bias tasks is a promising new indicator of affective valence in animals. Rat studies support the hypothesis that animals in a negative affective state evaluate ambiguous cues negatively. Prior automated operant go/go judgement bias tasks have involved training rats that an auditory cue of one frequency predicts a Reward and a cue of a different frequency predicts a Punisher (RP task), and then measuring whether ambiguous cues of intermediate frequency are judged as predicting reward (‘optimism’) or punishment (‘pessimism’). We investigated whether an automated Reward–Reward (RR) task yielded similar results to, and was faster to train than, RP tasks. We also introduced a new ambiguity test (simultaneous presentation of the two training cues) alongside the standard single ambiguous cue test. Half of the rats experienced an unpredictable housing treatment (UHT) designed to induce a negative state. Control rats were relatively ‘pessimistic’, whilst UHT rats were quicker, but no less accurate, in their responses in the RR test, and showed less anxiety-like behaviour in independent tests. A possible reason for these findings is that rats adapted to and were stimulated by UHT, whilst control rats in a predictable environment were more sensitive to novelty and change. Responses in the new ambiguity test correlated positively with those in single ambiguous cue tests, and may provide a measure of attention bias. The RR task was quicker to train than previous automated RP tasks. Together, they could be used to disentangle how reward and punishment processes underpin affect-induced cognitive biases. PMID:25106739

Precise orbit determination of the Sentinel-3A altimetry satellite using ambiguity-fixed GPS carrier phase observations

NASA Astrophysics Data System (ADS)

Montenbruck, Oliver; Hackel, Stefan; Jäggi, Adrian

2017-11-01

The Sentinel-3 mission takes routine measurements of sea surface heights and depends crucially on accurate and precise knowledge of the spacecraft. Orbit determination with a targeted uncertainty of less than 2 cm in radial direction is supported through an onboard Global Positioning System (GPS) receiver, a Doppler Orbitography and Radiopositioning Integrated by Satellite instrument, and a complementary laser retroreflector for satellite laser ranging. Within this study, the potential of ambiguity fixing for GPS-only precise orbit determination (POD) of the Sentinel-3 spacecraft is assessed. A refined strategy for carrier phase generation out of low-level measurements is employed to cope with half-cycle ambiguities in the tracking of the Sentinel-3 GPS receiver that have so far inhibited ambiguity-fixed POD solutions. Rather than explicitly fixing double-difference phase ambiguities with respect to a network of terrestrial reference stations, a single-receiver ambiguity resolution concept is employed that builds on dedicated GPS orbit, clock, and wide-lane bias products provided by the CNES/CLS (Centre National d'Études Spatiales/Collecte Localisation Satellites) analysis center of the International GNSS Service. Compared to float ambiguity solutions, a notably improved precision can be inferred from laser ranging residuals. These decrease from roughly 9 mm down to 5 mm standard deviation for high-grade stations on average over low and high elevations. Furthermore, the ambiguity-fixed orbits offer a substantially improved cross-track accuracy and help to identify lateral offsets in the GPS antenna or center-of-mass (CoM) location. With respect to altimetry, the improved orbit precision also benefits the global consistency of sea surface measurements. However, modeling of the absolute height continues to rely on proper dynamical models for the spacecraft motion as well as ground calibrations for the relative position of the altimeter reference point and the CoM.

Translation Ambiguity but Not Word Class Predicts Translation Performance

ERIC Educational Resources Information Center

Prior, Anat; Kroll, Judith F.; Macwhinney, Brian

2013-01-01

We investigated the influence of word class and translation ambiguity on cross-linguistic representation and processing. Bilingual speakers of English and Spanish performed translation production and translation recognition tasks on nouns and verbs in both languages. Words either had a single translation or more than one translation. Translation…

Aggression in Teachers is Related to Role Conflict and Role Ambiguity as Occupational Stress.

PubMed

Kanchika, Masaru; Iwasaki, Shinichi; Konish, Akihito; Deguchi, Yasuhiko; Kobayashi, Yumi; Nakada, Akihiro; Inoue, Koki

2015-12-01

Aggression in the workplace is increasingly recognized as a serious problem, but there are few studies about worker aggression toward outsiders in the workplace. We investigated the association between aggression and occupational stress among teachers. This was a cross-sectional study of 1583 teachers, principals, and vice-principals. Aggression was measured using the Japanese version of the Buss-Perry Aggression Questionnaire (BAQ). The survey respondents were classified into tertiles according to the BAQ score. The high BAQ group was defined as the upper tertile for the BAQ total score (BAQ total score 625). Occupational stress was measured using the Japanese version of the Generic Job Stress Questionnaire. Comparisons among the groups were performed using multiple logistic regression analysis. Of the 1583 respondents, 488 were included in the high BAQ group. After adjusting for demographic and occupational variables, high role conflict and role ambiguity were significantly associated with belonging to the high BAQ group. In subscales of the BAQ, high role conflict and role ambiguity related to high levels of hostility, and physical aggression. Occupational stress such as role conflict and role ambiguity was associated with aggression among teachers. It is necessary to reduce problems which relates to role conflict and role ambiguity for preventing teachers' aggression.

Ambiguity and Inconsistencies in Mathematics Spoken in the Classroom: The Need for Teacher Training and Rules for Communication of Mathematics

ERIC Educational Resources Information Center

Isaacson, M.D.; Srinivasan, S.; Lloyd, L.L.

2012-01-01

Mathematics has the potential for being spoken ambiguously. This is problematic for many students, in particular those who have disabilities that inhibit processing of printed material. This paper documents the magnitude of potential ambiguity arising from textbooks and provides a measure of the degree to which potential ambiguity is actualized…

Long-Duration Spaceflight Increases Depth Ambiguity of Reversible Perspective Figures

PubMed Central

Clément, Gilles; Allaway, Heather C. M.; Demel, Michael; Golemis, Adrianos; Kindrat, Alexandra N.; Melinyshyn, Alexander N.; Merali, Tahir; Thirsk, Robert

2015-01-01

The objective of this study was to investigate depth perception in astronauts during and after spaceflight by studying their sensitivity to reversible perspective figures in which two-dimensional images could elicit two possible depth representations. Other ambiguous figures that did not give rise to a perception of illusory depth were used as controls. Six astronauts and 14 subjects were tested in the laboratory during three sessions for evaluating the variability of their responses in normal gravity. The six astronauts were then tested during four sessions while on board the International Space Station for 5–6 months. They were finally tested immediately after return to Earth and up to one week later. The reaction time decreased throughout the sessions, thus indicating a learning effect. However, the time to first percept reversal and the number of reversals were not different in orbit and after the flight compared to before the flight. On Earth, when watching depth-ambiguous perspective figures, all subjects reported seeing one three-dimensional interpretation more often than the other, i.e. a ratio of about 70–30%. In weightlessness this asymmetry gradually disappeared and after 3 months in orbit both interpretations were seen for the same duration. These results indicate that the perception of “illusory” depth is altered in astronauts during spaceflight. This increased depth ambiguity is attributed to the lack of the gravitational reference and the eye-ground elevation for interpreting perspective depth cues. PMID:26146839

Long-Duration Spaceflight Increases Depth Ambiguity of Reversible Perspective Figures.

PubMed

Clément, Gilles; Allaway, Heather C M; Demel, Michael; Golemis, Adrianos; Kindrat, Alexandra N; Melinyshyn, Alexander N; Merali, Tahir; Thirsk, Robert

2015-01-01

The objective of this study was to investigate depth perception in astronauts during and after spaceflight by studying their sensitivity to reversible perspective figures in which two-dimensional images could elicit two possible depth representations. Other ambiguous figures that did not give rise to a perception of illusory depth were used as controls. Six astronauts and 14 subjects were tested in the laboratory during three sessions for evaluating the variability of their responses in normal gravity. The six astronauts were then tested during four sessions while on board the International Space Station for 5-6 months. They were finally tested immediately after return to Earth and up to one week later. The reaction time decreased throughout the sessions, thus indicating a learning effect. However, the time to first percept reversal and the number of reversals were not different in orbit and after the flight compared to before the flight. On Earth, when watching depth-ambiguous perspective figures, all subjects reported seeing one three-dimensional interpretation more often than the other, i.e. a ratio of about 70-30%. In weightlessness this asymmetry gradually disappeared and after 3 months in orbit both interpretations were seen for the same duration. These results indicate that the perception of "illusory" depth is altered in astronauts during spaceflight. This increased depth ambiguity is attributed to the lack of the gravitational reference and the eye-ground elevation for interpreting perspective depth cues.

Pointwise Partial Information Decomposition Using the Specificity and Ambiguity Lattices

NASA Astrophysics Data System (ADS)

Finn, Conor; Lizier, Joseph

2018-04-01

What are the distinct ways in which a set of predictor variables can provide information about a target variable? When does a variable provide unique information, when do variables share redundant information, and when do variables combine synergistically to provide complementary information? The redundancy lattice from the partial information decomposition of Williams and Beer provided a promising glimpse at the answer to these questions. However, this structure was constructed using a much criticised measure of redundant information, and despite sustained research, no completely satisfactory replacement measure has been proposed. In this paper, we take a different approach, applying the axiomatic derivation of the redundancy lattice to a single realisation from a set of discrete variables. To overcome the difficulty associated with signed pointwise mutual information, we apply this decomposition separately to the unsigned entropic components of pointwise mutual information which we refer to as the specificity and ambiguity. This yields a separate redundancy lattice for each component. Then based upon an operational interpretation of redundancy, we define measures of redundant specificity and ambiguity enabling us to evaluate the partial information atoms in each lattice. These atoms can be recombined to yield the sought-after multivariate information decomposition. We apply this framework to canonical examples from the literature and discuss the results and the various properties of the decomposition. In particular, the pointwise decomposition using specificity and ambiguity satisfies a chain rule over target variables, which provides new insights into the so-called two-bit-copy example.

Teaching weight to explicitly address language ambiguities and conceptual difficulties

NASA Astrophysics Data System (ADS)

Taibu, Rex; Schuster, David; Rudge, David

2017-06-01

Language ambiguities in concept meanings can exacerbate student learning difficulties and conceptual understanding of physics concepts. This is especially true for the concept of "weight," which has multiple meanings in both scientific and everyday usage. The term weight has been defined in several different ways, with nuances, but in textbooks and teaching the term is almost always defined in one of two ways: operationally either as the contact force between an object and a measuring scale or as the gravitational force on an object due to some other body such as Earth. The use of the same name for different concepts leads to much confusion, especially in accelerating situations, and to conflicting notions of "weightlessness" in free fall situations. In the present paper, we share an innovative approach that initially avoids the term weight entirely while teaching the physics of each situation, and then teaches the language ambiguities explicitly. We developed an instructional module with this approach and implemented it over two terms in three sections of an introductory physics course for preservice elementary teachers. Learning gains for content understanding were assessed using pretests and post-tests. Participants achieved remarkably high gains for both static and accelerating situations. Surveys pre- and postinstruction showed substantially improved appreciation of language issues and ambiguities associated with weight, weightlessness, and free fall. Interviews with instructors teaching the module provided additional insight into the advantages and teaching demands of the new approach.

Impaired semantic inhibition during lexical ambiguity repetition in Parkinson's disease.

PubMed

Copland, David A; Sefe, Gameli; Ashley, Jane; Hudson, Carrie; Chenery, Helen J

2009-09-01

Impairments of semantic processing and inhibition have been observed in Parkinson's disease (PD), however, the consequences of faulty meaning selection and suppression have not been considered in terms of subsequent lexical processing. The present study employed a lexical ambiguity repetition paradigm where the first presentation of an ambiguity paired with a target biasing its dominant or subordinate meaning (e.g., bank - money or bank - river) was followed after several intervening trials by a presentation of the same ambiguity paired with a different target that biases the same (congruent) or a different (incongruent) meaning to that biased on the first presentation. Meaning dominance (dominant or subordinate weaker meanings) and interstimulus interval (ISI) were manipulated. Analyses conducted on the second presentation indicated priming of congruent meanings and no priming for the incongruent meanings at both short and long ISIs in the healthy controls, consistent with suppression of meanings competing with the representation biased in the first presentation. In contrast, the PD group failed to dampen activation for the incongruent meaning at the long ISI when the first presentation was subordinate. This pattern is consistent with an impairment of meaning suppression which is observed under controlled processing conditions and varies as a function of meaning dominance of the first presentation. These findings further refine our understanding of lexical-semantic impairments in PD and suggest a mechanism that may contribute to discourse comprehension impairments in this population.

Varying acoustic-phonemic ambiguity reveals that talker normalization is obligatory in speech processing.

PubMed

Choi, Ja Young; Hu, Elly R; Perrachione, Tyler K

2018-04-01

The nondeterministic relationship between speech acoustics and abstract phonemic representations imposes a challenge for listeners to maintain perceptual constancy despite the highly variable acoustic realization of speech. Talker normalization facilitates speech processing by reducing the degrees of freedom for mapping between encountered speech and phonemic representations. While this process has been proposed to facilitate the perception of ambiguous speech sounds, it is currently unknown whether talker normalization is affected by the degree of potential ambiguity in acoustic-phonemic mapping. We explored the effects of talker normalization on speech processing in a series of speeded classification paradigms, parametrically manipulating the potential for inconsistent acoustic-phonemic relationships across talkers for both consonants and vowels. Listeners identified words with varying potential acoustic-phonemic ambiguity across talkers (e.g., beet/boat vs. boot/boat) spoken by single or mixed talkers. Auditory categorization of words was always slower when listening to mixed talkers compared to a single talker, even when there was no potential acoustic ambiguity between target sounds. Moreover, the processing cost imposed by mixed talkers was greatest when words had the most potential acoustic-phonemic overlap across talkers. Models of acoustic dissimilarity between target speech sounds did not account for the pattern of results. These results suggest (a) that talker normalization incurs the greatest processing cost when disambiguating highly confusable sounds and (b) that talker normalization appears to be an obligatory component of speech perception, taking place even when the acoustic-phonemic relationships across sounds are unambiguous.

Long-term priming of the meanings of ambiguous words

ERIC Educational Resources Information Center

Rodd, Jennifer M.; Lopez Cutrin, Belen; Kirsch, Hannah; Millar, Allesandra; Davis, Matthew H.

2013-01-01

Comprehension of semantically ambiguous words (e.g., "bark") is strongly influenced by the relative frequencies of their meanings, such that listeners are biased towards retrieving the most frequent meaning. These biases are often assumed to reflect a highly stable property of an individual's long-term lexical-semantic representations. We present…

Is adolescent-onset first-episode psychosis different from adult onset?

PubMed

Ballageer, Trevor; Malla, Ashok; Manchanda, Rahul; Takhar, Jatinder; Haricharan, Raj

2005-08-01

To examine whether first-episode psychosis patients with onset during adolescence (ages 15-18) differ significantly from those with young-adult onset (ages 19-30). Consecutive patients presenting with first-episode psychosis (N = 242) were assessed for demographic and illness characteristics such as duration of untreated psychosis, diagnosis, length of prodromal period, premorbid adjustment, level of psychotic, negative, depressive, anxiety, and extrapyramidal symptoms, and alcohol and drug use. Eighty-two patients (40.8%) had an onset of psychosis during adolescence (ages 15-18) and 119 (59.2%) during young adulthood (ages 19-30). The adolescent-onset group experienced longer delays in treatment of psychosis (duration of untreated psychosis) (p < .02), showed modestly worse premorbid functioning during late adolescence (p < .05), and were more likely to present with bizarre behavior (p < .01) and primary negative symptoms (p < .01). Patients with adolescent onset of psychosis are more likely to present with clinical characteristics that portend a poorer outcome and may require a different approach to early identification and treatment.

Otoacoustic emissions measured in rhesus monkeys (Macaca mulatta)

NASA Astrophysics Data System (ADS)

McFadden, Dennis; Pasanen, Edward G.; Raper, Jessica; Wallen, Kim

2003-10-01

In humans, otoacoustic emissions (OAEs) are stronger in females than in males and stronger in right ears than in left. The physiological bases for these differences are unknown, but several lines of circumstantial evidence suggest that the sex difference is attributable to androgenizing mechanisms operating during prenatal development. Specifically, it appears that exposure to high levels of androgens during prenatal development diminishes the strength of the cochlear amplifiers and thus the strength of the OAEs. Sex and ear differences in OAEs have not been well studied in species other than humans. Accordingly, click-evoked OAEs and distortion-product OAEs were measured in nine female and nine male rhesus monkeys. For CEOAEs, but less clearly for DPOAEs, females exhibited significantly stronger OAEs than males. There was no consistent ear difference for either sex for either type of OAE. In order to better study the early components of the CEOAE waveform, a nonlinear procedure [Molenaar et al., Hearing Res. 143, 197-207 (2002)] was used to collect CEOAEs along with our standard (linear) procedure. This colony also contains animals of each sex that were treated with androgenic or antiandrogenic agents during prenatal development, and OAEs are also currently being measured on those animals. [Work supported by NIDCD.

ALK ambiguous-positive non-small cell lung cancers are tumors challenged by diagnostic and therapeutic issues.

PubMed

Uguen, Arnaud; Andrieu-Key, Sophie; Vergne, Florence; Descourt, Renaud; Quéré, Gilles; Quintin-Roué, Isabelle; Key, Stéphane; Guéguen, Paul; Talagas, Matthieu; De Braekeleer, Marc; Marcorelles, Pascale

2016-09-01

Searching for ALK rearrangements using the approved fluorescent in situ hybridization (FISH) test and complementary immunohistochemistry (IHC) has become the rule to treat patients with advanced non‑small cell lung cancer (NSCLC) with anti‑ALK targeted therapy. The concordance between the two techniques is reported to be strong but imperfect. We report our experience with cases of ALK‑rearranged lung adenocarcinomas pointing out particularly ambiguous cases. FISH and IHC data on ALK but also c‑MET IHC as well as EGFR and KRAS mutation screening are considered, together with response to crizotinib treatment. We classified the 55 FISH ALK‑rearranged tumors into two groups according to the FISH and IHC results: a concordant FISH+IHC+ group (31 tumors) and an ambiguous group (24 tumors). These tumors were considered as 'ambiguous' ALK‑positive due to negative (21 tumors) or non‑contributive (3 tumors) IHC. In addition, the percentage of FISH-positive nuclei was between 15 and 20% in 17 tumors belonging to one or the other group (now called borderline tumors). We discuss the accuracy of the different tests with intent to determine whether ambiguous and borderline tumors are real positive ALK‑rearranged tumors. To conclude, ambiguous ALK‑positive lung cancers are challenging tumors with diagnosis and therapeutic issues that can justify parallel FISH, IHC and molecular screening strategy.

The impact of cochlear fine structure on hearing thresholds and DPOAE levels

NASA Astrophysics Data System (ADS)

Lee, Jungmee; Long, Glenis; Talmadge, Carrick L.

2004-05-01

Although otoacoustic emissions (OAE) are used as clinical and research tools, the correlation between OAE behavioral estimates of hearing status is not large. In normal-hearing individuals, the level of OAEs can vary as much as 30 dB when the frequency is changed less than 5%. These pseudoperiodic variations of OAE level with frequency are known as fine structure. Hearing thresholds measured with high-frequency resolution reveals a similar (up to 15 dB) fine structure. We examine the impact of OAE and threshold fine structures on the prediction of auditory thresholds from OAE levels. Distortion product otoacoustic emissions (DPOAEs) were measured with sweeping primary tones. Psychoacoustic detection thresholds were measured using pure tones, sweep tones, FM tones, and narrow-band noise. Sweep DPOAE and narrow-band threshold estimates provide estimates that are less influenced by cochlear fine structure and should lead to a higher correlation between OAE levels and psychoacoustic thresholds. [Research supported by PSC CUNY, NIDCD, National Institute on Disability and Rehabilitation Research in U.S. Department of Education, and The Ministry of Education in Korea.

Seven Types of Ambiguity in Evaluating the Impact of Humanities Provision in Undergraduate Medicine Curricula.

PubMed

Bleakley, Alan

2015-12-01

Inclusion of the humanities in undergraduate medicine curricula remains controversial. Skeptics have placed the burden of proof of effectiveness upon the shoulders of advocates, but this may lead to pursuing measurement of the immeasurable, deflecting attention away from the more pressing task of defining what we mean by the humanities in medicine. While humanities input can offer a fundamental critical counterweight to a potentially reductive biomedical science education, a new wave of thinking suggests that the kinds of arts and humanities currently used in medical education are neither radical nor critical enough to have a deep effect on students' learning and may need to be reformulated. The humanities can certainly educate for tolerance of ambiguity as a basis to learning democratic habits for contemporary team-based clinical work. William Empson's 'seven types of ambiguity' model for analyzing poetry is transposed to medical education to: (a) formulate seven values proffered by the humanities for improving medical education; (b) offer seven ways of measuring impact of medical humanities provision, thereby reducing ambiguity; and (c) --as a counterweight to (b) - celebrate seven types of ambiguity in contemporary medical humanities that critically reconsider issues of proof of impact.

Perceiving racism in ambiguous situations: who relies on easy-to-use information?

PubMed

Corning, Alexandra F; Bucchianeri, Michaela M

2010-01-01

In situations that are ambiguous with regard to the presence of discrimination, how do people arrive at their conclusions that discrimination has (or has not) taken place? This question was examined from a motivated social cognition perspective via the interaction of two factors: the prototype effect--the notion that ambiguously discriminatory behavior is more likely to be perceived as discriminatory when the executor is prototypical and the need for cognitive closure--the tendency to jump hastily to and seize on an answer. Results provided replicating evidence of the prototype effect among European American participants but not among African American participants. Specifically, European Americans were likely to perceive ambiguously racist behavior enacted by a prototypical executor (i.e., a White person) as more discriminatory than the same behavior exhibited by a non-prototypical executor (i.e., a Black person). African American participants, on the other hand, showed no reliance on this simple cognitive heuristic. Furthermore, results showed that European Americans with a higher need for cognitive closure were more likely to rely on the easy-to-use information offered by prototypes. These findings are discussed from a motivated social cognition perspective.

Calibration of Magnetometers with GNSS Receivers and Magnetometer-Aided GNSS Ambiguity Fixing.

PubMed

Henkel, Patrick

2017-06-08

Magnetometers provide compass information, and are widely used for navigation, orientation and alignment of objects. As magnetometers are affected by sensor biases and eventually by systematic distortions of the Earth magnetic field, a calibration is needed. In this paper, a method for calibration of magnetometers with three Global Navigation Satellite System (GNSS) receivers is presented. We perform a least-squares estimation of the magnetic flux and sensor biases using GNSS-based attitude information. The attitude is obtained from the relative positions between the GNSS receivers in the North-East-Down coordinate frame and prior knowledge of these relative positions in the platform's coordinate frame. The relative positions and integer ambiguities of the periodic carrier phase measurements are determined with an integer least-squares estimation using an integer decorrelation and sequential tree search. Prior knowledge on the relative positions is used to increase the success rate of ambiguity fixing. We have validated the proposed method with low-cost magnetometers and GNSS receivers on a vehicle in a test drive. The calibration enabled a consistent heading determination with an accuracy of five degrees. This precise magnetometer-based attitude information allows an instantaneous GNSS integer ambiguity fixing.

Calibration of Magnetometers with GNSS Receivers and Magnetometer-Aided GNSS Ambiguity Fixing

PubMed Central

Henkel, Patrick

2017-01-01

Magnetometers provide compass information, and are widely used for navigation, orientation and alignment of objects. As magnetometers are affected by sensor biases and eventually by systematic distortions of the Earth magnetic field, a calibration is needed. In this paper, a method for calibration of magnetometers with three Global Navigation Satellite System (GNSS) receivers is presented. We perform a least-squares estimation of the magnetic flux and sensor biases using GNSS-based attitude information. The attitude is obtained from the relative positions between the GNSS receivers in the North-East-Down coordinate frame and prior knowledge of these relative positions in the platform’s coordinate frame. The relative positions and integer ambiguities of the periodic carrier phase measurements are determined with an integer least-squares estimation using an integer decorrelation and sequential tree search. Prior knowledge on the relative positions is used to increase the success rate of ambiguity fixing. We have validated the proposed method with low-cost magnetometers and GNSS receivers on a vehicle in a test drive. The calibration enabled a consistent heading determination with an accuracy of five degrees. This precise magnetometer-based attitude information allows an instantaneous GNSS integer ambiguity fixing. PMID:28594369

Ambiguity of Quality in Remote Sensing Data

NASA Technical Reports Server (NTRS)

Lynnes, Christopher; Leptoukh, Greg

2010-01-01

This slide presentation reviews some of the issues in quality of remote sensing data. Data "quality" is used in several different contexts in remote sensing data, with quite different meanings. At the pixel level, quality typically refers to a quality control process exercised by the processing algorithm, not an explicit declaration of accuracy or precision. File level quality is usually a statistical summary of the pixel-level quality but is of doubtful use for scenes covering large areal extents. Quality at the dataset or product level, on the other hand, usually refers to how accurately the dataset is believed to represent the physical quantities it purports to measure. This assessment often bears but an indirect relationship at best to pixel level quality. In addition to ambiguity at different levels of granularity, ambiguity is endemic within levels. Pixel-level quality terms vary widely, as do recommendations for use of these flags. At the dataset/product level, quality for low-resolution gridded products is often extrapolated from validation campaigns using high spatial resolution swath data, a suspect practice at best. Making use of quality at all levels is complicated by the dependence on application needs. We will present examples of the various meanings of quality in remote sensing data and possible ways forward toward a more unified and usable quality framework.

Textbook Presentations of Weight: Conceptual Difficulties and Language Ambiguities

ERIC Educational Resources Information Center

Taibu, Rex; Rudge, David; Schuster, David

2015-01-01

The term "weight" has multiple related meanings in both scientific and everyday usage. Even among experts and in textbooks, weight is ambiguously defined as either the gravitational force on an object or operationally as the magnitude of the force an object exerts on a measuring scale. This poses both conceptual and language difficulties…

Chasing Ambiguity: Critical Reflections on Working with Dance Graduates

ERIC Educational Resources Information Center

Roe, Sarah

2017-01-01

This paper questions whether are we able to foster uncertainty and ambiguity within higher education arts programmes, specifically alongside current institutional demands and embedded pedagogies. If not, then what effect does this have on current dance graduates? I attend to these questions through critical reflections upon my work as a pedagogue,…

The processing of lexical ambiguity in healthy ageing and Parkinson׳s disease: role of cortico-subcortical networks.

PubMed

Ketteler, Simon; Ketteler, Daniel; Vohn, René; Kastrau, Frank; Schulz, Jörg B; Reetz, Kathrin; Huber, Walter

2014-09-18

Previous neuroimaging studies showed that correct resolution of lexical ambiguity relies on the integrity of prefrontal and inferior parietal cortices. Whereas prefrontal brain areas were associated with executive control over semantic selection, inferior parietal areas were linked with access to modality-independent representations of semantic memory. Yet insufficiently understood is the contribution of subcortical structures in ambiguity processing. Patients with disturbed basal ganglia function such as Parkinson׳s disease (PD) showed development of discourse comprehension deficits evoked by lexical ambiguity. To further investigate the engagement of cortico-subcortical networks functional Magnetic Resonance Imaging (fMRI) was monitored during ambiguity resolution in eight early PD patients without dementia and 14 age- and education-matched controls. Participants were required to relate meanings to a lexically ambiguous target (homonym). Each stimulus consisted of two words arranged on top of a screen, which had to be attributed to a homonym at the bottom. Brain activity was found in bilateral inferior parietal (BA 39), right middle temporal (BA 21/22), left middle frontal (BA 10) and bilateral inferior frontal areas (BA 45/46). Extent and amplitude of activity in the angular gyrus changed depending on semantic association strength that varied between conditions. Less activity in the left caudate was associated with semantic integration deficits in PD. The results of the present study suggest a relationship between subtle language deficits and early stages of basal ganglia dysfunction. Uncovering impairments in ambiguity resolution may be of future use in the neuropsychological assessment of non-motor deficits in PD. Copyright © 2014 Elsevier B.V. All rights reserved.

Rapid ambiguity resolution over medium-to-long baselines based on GPS/BDS multi-frequency observables

NASA Astrophysics Data System (ADS)

Gong, Xiaopeng; Lou, Yidong; Liu, Wanke; Zheng, Fu; Gu, Shengfeng; Wang, Hua

2017-02-01

Medium-long baseline RTK positioning generally needs a long initial time to find an accurate position due to non-negligible atmospheric delay residual. In order to shorten the initial or re-convergence time, a rapid phase ambiguity resolution method is employed based on GPS/BDS multi-frequency observables in this paper. This method is realized by two steps. First, double-differenced un-combined observables (i.e., L1/L2 and B1/B2/B3 observables) are used to obtain a float solution with atmospheric delay estimated as random walk parameter by using Kalman filter. This model enables an easy and consistent implementation for different systems and different frequency observables and can readily be extended to use more satellite navigation systems (e.g., Galileo, QZSS). Additional prior constraints for atmospheric information can be quickly added as well, because atmospheric delay is parameterized. Second, in order to fix ambiguity rapidly and reliably, ambiguities are divided into three types (extra-wide-lane (EWL), wide-lane (WL) and narrow-lane (NL)) according to their wavelengths and are to be fixed sequentially by using the LAMBDA method. Several baselines ranging from 61 km to 232 km collected by Trimble and Panda receivers are used to validate the method. The results illustrate that it only takes approximately 1, 2 and 6 epochs (30 s intervals) to fix EWL, WL and NL ambiguities, respectively. More epochs' observables are needed to fix WL and NL ambiguity around local time 14:00 than other time mainly due to more active ionosphere activity. As for the re-convergence time, the simulated results show that 90% of epochs can be fixed within 2 epochs by using prior atmospheric delay information obtained from previously 5 min. Finally, as for positioning accuracy, meter, decimeter and centimeter level positioning results are obtained according to different ambiguity resolution performances, i.e., EWL, WL and NL fixed solutions.

"The impact of uncertain threat on affective bias: Individual differences in response to ambiguity": Correction.

PubMed

2018-04-01

Reports an error in "The impact of uncertain threat on affective bias: Individual differences in response to ambiguity" by Maital Neta, Julie Cantelon, Zachary Haga, Caroline R. Mahoney, Holly A. Taylor and F. Caroline Davis ( Emotion , 2017[Dec], Vol 17[8], 1137-1143). In this article, the copyright attribution was incorrectly listed under the Creative Commons CC-BY license due to production-related error. The correct copyright should be "In the public domain." The online version of this article has been corrected. (The following abstract of the original article appeared in record 2017-40275-001.) Individuals who operate under highly stressful conditions (e.g., military personnel and first responders) are often faced with the challenge of quickly interpreting ambiguous information in uncertain and threatening environments. When faced with ambiguity, it is likely adaptive to view potentially dangerous stimuli as threatening until contextual information proves otherwise. One laboratory-based paradigm that can be used to simulate uncertain threat is known as threat of shock (TOS), in which participants are told that they might receive mild but unpredictable electric shocks while performing an unrelated task. The uncertainty associated with this potential threat induces a state of emotional arousal that is not overwhelmingly stressful, but has widespread-both adaptive and maladaptive-effects on cognitive and affective function. For example, TOS is thought to enhance aversive processing and abolish positivity bias. Importantly, in certain situations (e.g., when walking home alone at night), this anxiety can promote an adaptive state of heightened vigilance and defense mobilization. In the present study, we used TOS to examine the effects of uncertain threat on valence bias, or the tendency to interpret ambiguous social cues as positive or negative. As predicted, we found that heightened emotional arousal elicited by TOS was associated with an increased tendency to

Top-down influences on ambiguous perception: the role of stable and transient states of the observer

PubMed Central

Scocchia, Lisa; Valsecchi, Matteo; Triesch, Jochen

2014-01-01

The world as it appears to the viewer is the result of a complex process of inference performed by the brain. The validity of this apparently counter-intuitive assertion becomes evident whenever we face noisy, feeble or ambiguous visual stimulation: in these conditions, the state of the observer may play a decisive role in determining what is currently perceived. On this background, ambiguous perception and its amenability to top-down influences can be employed as an empirical paradigm to explore the principles of perception. Here we offer an overview of both classical and recent contributions on how stable and transient states of the observer can impact ambiguous perception. As to the influence of the stable states of the observer, we show that what is currently perceived can be influenced (1) by cognitive and affective aspects, such as meaning, prior knowledge, motivation, and emotional content and (2) by individual differences, such as gender, handedness, genetic inheritance, clinical conditions, and personality traits and by (3) learning and conditioning. As to the impact of transient states of the observer, we outline the effects of (4) attention and (5) voluntary control, which have attracted much empirical work along the history of ambiguous perception. In the huge literature on the topic we trace a difference between the observer's ability to control dominance (i.e., the maintenance of a specific percept in visual awareness) and reversal rate (i.e., the switching between two alternative percepts). Other transient states of the observer that have more recently drawn researchers' attention regard (6) the effects of imagery and visual working memory. (7) Furthermore, we describe the transient effects of prior history of perceptual dominance. (8) Finally, we address the currently available computational models of ambiguous perception and how they can take into account the crucial share played by the state of the observer in perceiving ambiguous displays. PMID

Pragmatic Failure and Referential Ambiguity when Attorneys Ask Child Witnesses “Do You Know/Remember” Questions

PubMed Central

Evans, Angela D.; Stolzenberg, Stacia N.; Lyon, Thomas D.

2016-01-01

“Do you know” and “Do you remember” (DYK/R) questions explicitly ask whether one knows or remembers some information while implicitly asking for that information. This study examined how 104 4- to 9-year-old children testifying in child sexual abuse cases responded to DYK/R wh- and yes/no questions. When asked DYK/R questions containing an implicit wh- question requesting information, children often provided unelaborated “Yes” responses. Attorneys’ follow-up questions suggested that children usually misunderstood the pragmatics of the questions. When DYK/R questions contained an implicit yes/no question, unelaborated “Yes” or “No” responses could be responding to the explicit or the implicit questions resulting in referentially ambiguous responses. Children often provided referentially ambiguous responses and attorneys usually failed to disambiguate children’s answers. Although pragmatic failure following DYK/R wh- questions decreased with age, the likelihood of referential ambiguity following DYK/R yes/no questions did not. The results highlight the risks of serious miscommunications caused by pragmatic misunderstanding and referential ambiguity when children testify. PMID:28652686

Rotation Matrix Method Based on Ambiguity Function for GNSS Attitude Determination.

PubMed

Yang, Yingdong; Mao, Xuchu; Tian, Weifeng

2016-06-08

Global navigation satellite systems (GNSS) are well suited for attitude determination. In this study, we use the rotation matrix method to resolve the attitude angle. This method achieves better performance in reducing computational complexity and selecting satellites. The condition of the baseline length is combined with the ambiguity function method (AFM) to search for integer ambiguity, and it is validated in reducing the span of candidates. The noise error is always the key factor to the success rate. It is closely related to the satellite geometry model. In contrast to the AFM, the LAMBDA (Least-squares AMBiguity Decorrelation Adjustment) method gets better results in solving the relationship of the geometric model and the noise error. Although the AFM is more flexible, it is lack of analysis on this aspect. In this study, the influence of the satellite geometry model on the success rate is analyzed in detail. The computation error and the noise error are effectively treated. Not only is the flexibility of the AFM inherited, but the success rate is also increased. An experiment is conducted in a selected campus, and the performance is proved to be effective. Our results are based on simulated and real-time GNSS data and are applied on single-frequency processing, which is known as one of the challenging case of GNSS attitude determination.

Interpreting ambiguous ‘trace’ results in Schistosoma mansoni CCA Tests: Estimating sensitivity and specificity of ambiguous results with no gold standard

PubMed Central

Donnelly, Christl A.; Fenwick, Alan; Kabatereine, Narcis B.; Knowles, Sarah C. L.; Meité, Aboulaye; N'Goran, Eliézer K.; Nalule, Yolisa; Nogaro, Sarah; Phillips, Anna E.; Tukahebwa, Edridah Muheki; Fleming, Fiona M.

2017-01-01

Background The development of new diagnostics is an important tool in the fight against disease. Latent Class Analysis (LCA) is used to estimate the sensitivity and specificity of tests in the absence of a gold standard. The main field diagnostic for Schistosoma mansoni infection, Kato-Katz (KK), is not very sensitive at low infection intensities. A point-of-care circulating cathodic antigen (CCA) test has been shown to be more sensitive than KK. However, CCA can return an ambiguous ‘trace’ result between ‘positive’ and ‘negative’, and much debate has focused on interpretation of traces results. Methodology/Principle findings We show how LCA can be extended to include ambiguous trace results and analyse S. mansoni studies from both Côte d’Ivoire (CdI) and Uganda. We compare the diagnostic performance of KK and CCA and the observed results by each test to the estimated infection prevalence in the population. Prevalence by KK was higher in CdI (13.4%) than in Uganda (6.1%), but prevalence by CCA was similar between countries, both when trace was assumed to be negative (CCAtn: 11.7% in CdI and 9.7% in Uganda) and positive (CCAtp: 20.1% in CdI and 22.5% in Uganda). The estimated sensitivity of CCA was more consistent between countries than the estimated sensitivity of KK, and estimated infection prevalence did not significantly differ between CdI (20.5%) and Uganda (19.1%). The prevalence by CCA with trace as positive did not differ significantly from estimates of infection prevalence in either country, whereas both KK and CCA with trace as negative significantly underestimated infection prevalence in both countries. Conclusions Incorporation of ambiguous results into an LCA enables the effect of different treatment thresholds to be directly assessed and is applicable in many fields. Our results showed that CCA with trace as positive most accurately estimated infection prevalence. PMID:29220354

Iterative Code-Aided ML Phase Estimation and Phase Ambiguity Resolution

NASA Astrophysics Data System (ADS)

Wymeersch, Henk; Moeneclaey, Marc

2005-12-01

As many coded systems operate at very low signal-to-noise ratios, synchronization becomes a very difficult task. In many cases, conventional algorithms will either require long training sequences or result in large BER degradations. By exploiting code properties, these problems can be avoided. In this contribution, we present several iterative maximum-likelihood (ML) algorithms for joint carrier phase estimation and ambiguity resolution. These algorithms operate on coded signals by accepting soft information from the MAP decoder. Issues of convergence and initialization are addressed in detail. Simulation results are presented for turbo codes, and are compared to performance results of conventional algorithms. Performance comparisons are carried out in terms of BER performance and mean square estimation error (MSEE). We show that the proposed algorithm reduces the MSEE and, more importantly, the BER degradation. Additionally, phase ambiguity resolution can be performed without resorting to a pilot sequence, thus improving the spectral efficiency.

Subsequent to suppression: Downstream comprehension consequences of noun/verb ambiguity in natural reading

PubMed Central

Stites, Mallory C.; Federmeier, Kara D.

2015-01-01

We used eye-tracking to investigate the downstream processing consequences of encountering noun/verb (NV) homographs (i.e., park) in semantically neutral but syntactically constraining contexts. Target words were followed by a prepositional phrase containing a noun that was plausible for only one meaning of the homograph. Replicating previous work, we found increased first fixation durations on NV homographs compared to unambiguous words, which persisted into the next sentence region. At the downstream noun, we found plausibility effects following ambiguous words that were correlated with the size of a reader's first fixation effect, suggesting that this effect reflects the recruitment of processing resources necessary to suppress the homograph's context-inappropriate meaning. Using these same stimuli, Lee and Federmeier (2012) found a sustained frontal negativity to the NV homographs, and, on the downstream noun, found a plausibility effect that was also positively correlated with the size of a reader's ambiguity effect. Together, these findings suggest that when only syntactic constraints are available, meaning selection recruits inhibitory mechanisms that can be measured in both first fixation slowdown and ERP ambiguity effects. PMID:25961358

Environmental and ecological upheval in shallow marine systems during the Early Jurassic (Pliensbachian and Toarcian)

NASA Astrophysics Data System (ADS)

Martindale, R. C.; Ettinger, N. P.; Bodin, S.; Kosir, A.; Brame, H. M. R.; Thibodeau, A. M.; Larson, T. E.; Kerans, C.

2017-12-01

Carbon cycle perturbations, such as the Toarcian Oceanic Anoxic Event (T-OAE), have a significant influence on marine communities (e.g., extinctions), as well as the nature of the sedimentary record (e.g., carbonate factory collapse and black shale deposition) and geochemical cycling. To date, there remains a gap in our knowledge about the shallow-water record of the T-OAE and the geochemical signature of this event. This research combines geochemical, sedimentological, and paleontological data from two shallow-water Early Jurassic records in Slovenia and Morocco. The Dinaric Carbonate Platform (Slovenia) records a relatively continuous record of Pliensbachian and Toarcian strata and captures the T-OAE in shallow-water carbonates. The Trnovski Gozd karst plateau (western Slovenia) contains Pleinsbachian lithiotid (bivalve) biostromes, coral bioherms, and a diverse assemblage of carbonate producing fauna. This work documents the geochemical and sedimentological signature of the T-OAE in shallow water carbonates and tests whether mercury concentrations link paleontological and sedimentological changes with the Karoo-Ferrar Large Igneous Province. Elemental data coupled with sedimentologic and stratigraphic evidence indicate a prolonged period of deoxygenation on the shelf coincident with both large igneous province activity and the OAE. The Moroccan High Atlas Mountains provide another excellent shallow-water record of the T-OAE, with a thick mixed carbonate-siliciclastic shelf-to-ramp setting with sustained deposition through the Early Jurassic interval. In Morocco there is no evidence for anoxia in this shallow-water locality; however, the carbonate factory collapses at the Pliensbachian-Toarcian stage boundary as well as the T-OAE. Reef communities, particularly the lithiotid biostromes, persist across the stage boundary and are observed through to the T-OAE. The studied localities also record the oldest corals reefs following the T-OAE; coral reefs recover

Sensorimotor Adaptation Following Exposure to Ambiguous Inertial Motion Cues

NASA Technical Reports Server (NTRS)

Wood, S. J.; Clement, G. R.; Harm, D L.; Rupert, A. H.; Guedry, F. E.; Reschke, M. F.

2005-01-01

The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive accurate spatial orientation awareness. Our general hypothesis is that the central nervous system utilizes both multi-sensory integration and frequency segregation as neural strategies to resolve the ambiguity of tilt and translation stimuli. Movement in an altered gravity environment, such as weightlessness without a stable gravity reference, results in new patterns of sensory cues. For example, the semicircular canals, vision and neck proprioception provide information about head tilt on orbit without the normal otolith head-tilt position that is omnipresent on Earth. Adaptive changes in how inertial cues from the otolith system are integrated with other sensory information lead to perceptual and postural disturbances upon return to Earth s gravity. The primary goals of this ground-based research investigation are to explore physiological mechanisms and operational implications of disorientation and tilt-translation disturbances reported by crewmembers during and following re-entry, and to evaluate a tactile prosthesis as a countermeasure for improving control of whole-body orientation during tilt and translation motion.

Sensorimotor Adaptation Following Exposure to Ambiguous Inertial Motion Cues

NASA Technical Reports Server (NTRS)

Wood, S. J.; Clement, G. R.; Harm, D. L.; Rupert, A. H.; Guedry, F. E.; Reschke, M. F.

2005-01-01

The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive accurate spatial orientation awareness. Our general hypothesis is that the central nervous system utilizes both multi-sensory integration and frequency segregation as neural strategies to resolve the ambiguity of tilt and translation stimuli. Movement in an altered gravity environment, such as weightlessness without a stable gravity reference, results in new patterns of sensory cues. For example, the semicircular canals, vision and neck proprioception provide information about head tilt on orbit without the normal otolith head-tilt position that is omnipresent on Earth. Adaptive changes in how inertial cues from the otolith system are integrated with other sensory information lead to perceptual and postural disturbances upon return to Earth's gravity. The primary goals of this ground-based research investigation are to explore physiological mechanisms and operational implications of disorientation and tilt-translation disturbances reported by crewmembers during and following re-entry, and to evaluate a tactile prosthesis as a countermeasure for improving control of whole-body orientation during tilt and translation motion.

Biased Interpretation of Ambiguous Social Scenarios in Anorexia Nervosa.

PubMed

Cardi, Valentina; Turton, Robert; Schifano, Sylvia; Leppanen, Jenni; Hirsch, Colette R; Treasure, Janet

2017-01-01

Patients with anorexia nervosa experience increased sensitivity to the risk of social rejection. The aims of this study were to assess the interpretation of ambiguous social scenarios depicting the risk of rejection and to examine the relationship between interpretation biases and clinical symptoms. Thirty-five women with anorexia nervosa and 30 healthy eaters completed clinical questionnaires, alongside a sentence completion task. This task required participants to generate completions to ambiguous social scenarios and to endorse their best completion. Responses were rated as being negative, neutral or positive. Patients endorsed more negative interpretations and fewer neutral and positive interpretations compared with healthy eaters. The frequency of endorsed negative interpretations correlated with depression, anxiety and fear of weight gain and body disturbance. A negative interpretation bias towards social stimuli is present in women with anorexia nervosa and correlates with clinical symptoms. Interventions aimed at reducing this bias could improve illness prognosis. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Radiological Evaluation of Ambiguous Genitalia with Various Imaging Modalities

NASA Astrophysics Data System (ADS)

Ravi, N.; Bindushree, Kadakola

2012-07-01

Disorders of sex development (DSDs) are congenital conditions in which the development of chromosomal, gonadal, or anatomic sex is atypical. These can be classified broadly into four categories on the basis of gonadal histologic features: female pseudohermaphroditism (46,XX with two ovaries); male pseudohermaphroditism (46,XY with two testes); true hermaphroditism (ovotesticular DSD) (both ovarian and testicular tissues); and gonadal dysgenesis, either mixed (a testis and a streak gonad) or pure (bilateral streak gonads). Imaging plays an important role in demonstrating the anatomy and associated anomalies. Ultrasonography is the primary modality for demonstrating internal organs and magnetic resonance imaging is used as an adjunct modality to assess for internal gonads and genitalia. Early and appropriate gender assignment is necessary for healthy physical and psychologic development of children with ambiguous genitalia. Gender assignment can be facilitated with a team approach that involves a pediatric endocrinologist, geneticist, urologist, psychiatrist, social worker, neonatologist, nurse, and radiologist, allowing timely diagnosis and proper management. We describe case series on ambiguous genitalia presented to our department who were evaluated with multiple imaging modalities.

Efficient high-rate satellite clock estimation for PPP ambiguity resolution using carrier-ranges.

PubMed

Chen, Hua; Jiang, Weiping; Ge, Maorong; Wickert, Jens; Schuh, Harald

2014-11-25

In order to catch up the short-term clock variation of GNSS satellites, clock corrections must be estimated and updated at a high-rate for Precise Point Positioning (PPP). This estimation is already very time-consuming for the GPS constellation only as a great number of ambiguities need to be simultaneously estimated. However, on the one hand better estimates are expected by including more stations, and on the other hand satellites from different GNSS systems must be processed integratively for a reliable multi-GNSS positioning service. To alleviate the heavy computational burden, epoch-differenced observations are always employed where ambiguities are eliminated. As the epoch-differenced method can only derive temporal clock changes which have to be aligned to the absolute clocks but always in a rather complicated way, in this paper, an efficient method for high-rate clock estimation is proposed using the concept of "carrier-range" realized by means of PPP with integer ambiguity resolution. Processing procedures for both post- and real-time processing are developed, respectively. The experimental validation shows that the computation time could be reduced to about one sixth of that of the existing methods for post-processing and less than 1 s for processing a single epoch of a network with about 200 stations in real-time mode after all ambiguities are fixed. This confirms that the proposed processing strategy will enable the high-rate clock estimation for future multi-GNSS networks in post-processing and possibly also in real-time mode.

The influence of sense-contingent argument structure frequencies on ambiguity resolution in aphasia.

PubMed

Huck, Anneline; Thompson, Robin L; Cruice, Madeline; Marshall, Jane

2017-06-01

Verbs with multiple senses can show varying argument structure frequencies, depending on the underlying sense. When acknowledge is used to mean 'recognise', it takes a direct object (DO), but when it is used to mean 'admit' it prefers a sentence complement (SC). The purpose of this study was to investigate whether people with aphasia (PWA) can exploit such meaning-structure probabilities during the reading of temporarily ambiguous sentences, as demonstrated for neurologically healthy individuals (NHI) in a self-paced reading study (Hare et al., 2003). Eleven people with mild or moderate aphasia and eleven neurologically healthy control participants read sentences while their eyes were tracked. Using adapted materials from the study by Hare et al. target sentences containing an SC structure (e.g. He acknowledged (that) his friends would probably help him a lot) were presented following a context prime that biased either a direct object (DO-bias) or sentence complement (SC-bias) reading of the verbs. Half of the stimuli sentences did not contain that so made the post verbal noun phrase (his friends) structurally ambiguous. Both groups of participants were influenced by structural ambiguity as well as by the context bias, indicating that PWA can, like NHI, use their knowledge of a verb's sense-based argument structure frequency during online sentence reading. However, the individuals with aphasia showed delayed reading patterns and some individual differences in their sensitivity to context and ambiguity cues. These differences compared to the NHI may contribute to difficulties in sentence comprehension in aphasia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Visual word ambiguity.

PubMed

van Gemert, Jan C; Veenman, Cor J; Smeulders, Arnold W M; Geusebroek, Jan-Mark

2010-07-01

This paper studies automatic image classification by modeling soft assignment in the popular codebook model. The codebook model describes an image as a bag of discrete visual words selected from a vocabulary, where the frequency distributions of visual words in an image allow classification. One inherent component of the codebook model is the assignment of discrete visual words to continuous image features. Despite the clear mismatch of this hard assignment with the nature of continuous features, the approach has been successfully applied for some years. In this paper, we investigate four types of soft assignment of visual words to image features. We demonstrate that explicitly modeling visual word assignment ambiguity improves classification performance compared to the hard assignment of the traditional codebook model. The traditional codebook model is compared against our method for five well-known data sets: 15 natural scenes, Caltech-101, Caltech-256, and Pascal VOC 2007/2008. We demonstrate that large codebook vocabulary sizes completely deteriorate the performance of the traditional model, whereas the proposed model performs consistently. Moreover, we show that our method profits in high-dimensional feature spaces and reaps higher benefits when increasing the number of image categories.

Impact of ambiguity and risk on decision making in mild Alzheimer's disease.

PubMed

Sinz, H; Zamarian, L; Benke, T; Wenning, G K; Delazer, M

2008-01-01

Decisions under ambiguity and decisions under risk are crucial types of decision making in daily living at any age. This is the first study assessing these two types of decisions in patients with mild dementia of Alzheimer's type (DAT) by means of the Iowa Gambling Task (IGT) and a newly developed, Probability-Associated Gambling (PAG) task. While rules for gains and losses are implicit in the IGT, in the PAG task rules are explicit and winning probabilities, which change from trial to trial, can be estimated. Results of the IGT indicated that DAT patients made more disadvantageous decisions than healthy controls. Patients also shifted more frequently among decks, i.e. under ambiguity decisions were taken randomly and no advantageous strategy was established over time by DAT patients. Thus, not only actual choices but also development of advantageous strategies may be revealing about decision making in the IGT. Compared to controls, patients demonstrated less advantageous choices in the PAG task as well. They gambled more often in the low winning probabilities and less frequently in the high probabilities than healthy participants. Patients' performance on both tasks correlated with measures of executive functions. Findings of the present investigation are consistent with the early pathological cerebral changes and related (cognitive, emotional) deficits reported for DAT. As suggested by our study, decisions under ambiguity as well as decisions under risk are impaired in mild DAT. It may thus be expected that patients with mild DAT have difficulties in taking decisions in every-day life situations, both in cases of ambiguity (information on probability is missing or conflicting, and the expected utility of the different options is incalculable) and in cases of risk (outcomes can be predicted by well-defined or estimable probabilities).

Control of spin ambiguity during reorientation of an energy dissipating body

NASA Technical Reports Server (NTRS)

Kaplan, M. H.; Cenker, R. J.

1973-01-01

A quasi-rigid body initially spinning about its minor principal axis and experiencing energy dissipation will enter a tumbling mode and eventually reorient itself such that stable spin about its major principal axis is achieved. However, in this final state the body may be spinning in a positive or negative sense with respect to its major axis and aligned in a positive or negative sense with the inertially fixed angular momentum vector. This ambiguity can be controlled only through an active system. The associated dynamical formulations and simulations of uncontrolled reorientations are presented. Three control schemes are discussed and results offered for specific examples. These schemes include displacement of internal masses, spinning up of internal inertia, and reaction jets, all of which have demonstrated the ability to control spin ambiguity.

Determination of Patterson group symmetry from sparse multi-crystal data sets in the presence of an indexing ambiguity.

PubMed

Gildea, Richard J; Winter, Graeme

2018-05-01

Combining X-ray diffraction data from multiple samples requires determination of the symmetry and resolution of any indexing ambiguity. For the partial data sets typical of in situ room-temperature experiments, determination of the correct symmetry is often not straightforward. The potential for indexing ambiguity in polar space groups is also an issue, although methods to resolve this are available if the true symmetry is known. Here, a method is presented to simultaneously resolve the determination of the Patterson symmetry and the indexing ambiguity for partial data sets. open access.

Phrase Length and Prosody in On-Line Ambiguity Resolution