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Sample records for explains visual crowding

  1. Taming Crowded Visual Scenes

    Science.gov (United States)

    2014-08-12

    bee  in  a   colony  of... bees ).  In  order  to  automatically  choose  the  queens  from  among  a  very  large  number  of   individuals...different   scenarios  of  crowd   escape  panic.  For  each  UMN  clip,  a  normal  starting  section   is

  2. Linking crowding, visual span, and reading.

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    He, Yingchen; Legge, Gordon E

    2017-09-01

    The visual span is hypothesized to be a sensory bottleneck on reading speed with crowding thought to be the major sensory factor limiting the size of the visual span. This proposed linkage between crowding, visual span, and reading speed is challenged by the finding that training to read crowded letters reduced crowding but did not improve reading speed (Chung, 2007). Here, we examined two properties of letter-recognition training that may influence the transfer to improved reading: the spatial arrangement of training stimuli and the presence of flankers. Three groups of nine young adults were trained with different configurations of letter stimuli at 10° in the lower visual field: a flanked-local group (flanked letters localized at one position), a flanked-distributed group (flanked letters distributed across different horizontal locations), and an isolated-distributed group (isolated and distributed letters). We found that distributed training, but not the presence of flankers, appears to be necessary for the training benefit to transfer to increased reading speed. Localized training may have biased attention to one specific, small area in the visual field, thereby failing to improve reading. We conclude that the visual span represents a sensory bottleneck on reading, but there may also be an attentional bottleneck. Reducing the impact of crowding can enlarge the visual span and can potentially facilitate reading, but not when adverse attentional bias is present. Our results clarify the association between crowding, visual span, and reading.

  3. The wisdom of crowds for visual search.

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    Juni, Mordechai Z; Eckstein, Miguel P

    2017-05-23

    Decision-making accuracy typically increases through collective integration of people's judgments into group decisions, a phenomenon known as the wisdom of crowds. For simple perceptual laboratory tasks, classic signal detection theory specifies the upper limit for collective integration benefits obtained by weighted averaging of people's confidences, and simple majority voting can often approximate that limit. Life-critical perceptual decisions often involve searching large image data (e.g., medical, security, and aerial imagery), but the expected benefits and merits of using different pooling algorithms are unknown for such tasks. Here, we show that expected pooling benefits are significantly greater for visual search than for single-location perceptual tasks and the prediction given by classic signal detection theory. In addition, we show that simple majority voting obtains inferior accuracy benefits for visual search relative to averaging and weighted averaging of observers' confidences. Analysis of gaze behavior across observers suggests that the greater collective integration benefits for visual search arise from an interaction between the foveated properties of the human visual system (high foveal acuity and low peripheral acuity) and observers' nonexhaustive search patterns, and can be predicted by an extended signal detection theory framework with trial to trial sampling from a varying mixture of high and low target detectabilities across observers (SDT-MIX). These findings advance our theoretical understanding of how to predict and enhance the wisdom of crowds for real world search tasks and could apply more generally to any decision-making task for which the minority of group members with high expertise varies from decision to decision.

  4. Individual differences in visual field shape modulate the effects of attention on the lower visual field advantage in crowding.

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    Fortenbaugh, Francesca C; Silver, Michael A; Robertson, Lynn C

    2015-02-12

    It has previously been reported that visual crowding of a target by flankers is stronger in the upper visual field than in the lower, and this finding has been attributed to greater attentional resolution in the lower hemifield (He, Cavanagh, & Intriligator, 1996). Here we show that the upper/lower asymmetry in visual crowding can be explained by natural variations in the borders of each individual's visual field. Specifically, asymmetry in crowding along the vertical meridian can be almost entirely accounted for by replacing the conventional definition of visual field location, in units of degrees of visual angle, with a definition based on the ratio of the extents of an individual's upper and lower visual field. We also show that the upper/lower crowding asymmetry is eliminated when stimulus eccentricity is expressed in units of percentage of visual field extent but is present when the conventional measure of visual angle is used. We further demonstrate that the relationship between visual field extent and perceptual asymmetry is most evident when participants are able to focus their attention on the target location. These results reveal important influences of visual field boundaries on visual perception, even for visual field locations far from those boundaries. © 2015 ARVO.

  5. Does Temporal Integration Occur for Unrecognizable Words in Visual Crowding?

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    Jifan Zhou

    Full Text Available Visual crowding-the inability to see an object when it is surrounded by flankers in the periphery-does not block semantic activation: unrecognizable words due to visual crowding still generated robust semantic priming in subsequent lexical decision tasks. Based on the previous finding, the current study further explored whether unrecognizable crowded words can be temporally integrated into a phrase. By showing one word at a time, we presented Chinese four-word idioms with either a congruent or incongruent ending word in order to examine whether the three preceding crowded words can be temporally integrated to form a semantic context so as to affect the processing of the ending word. Results from both behavioral (Experiment 1 and Event-Related Potential (Experiment 2 and 3 measures showed congruency effect in only the non-crowded condition, which does not support the existence of unconscious multi-word integration. Aside from four-word idioms, we also found that two-word (modifier + adjective combination integration-the simplest kind of temporal semantic integration-did not occur in visual crowding (Experiment 4. Our findings suggest that integration of temporally separated words might require conscious awareness, at least under the timing conditions tested in the current study.

  6. Crowding deficits in the visual periphery of schizophrenia patients.

    Directory of Open Access Journals (Sweden)

    Rainer Kraehenmann

    Full Text Available Accumulating evidence suggests that basic visual information processing is impaired in schizophrenia. However, deficits in peripheral vision remain largely unexplored. Here we hypothesized that sensory processing of information in the visual periphery would be impaired in schizophrenia patients and, as a result, crowding - the breakdown in target recognition that occurs in cluttered visual environments - would be stronger. Therefore, we assessed visual crowding in the peripheral vision of schizophrenia patients and healthy controls. Subjects were asked to identify a target letter that was surrounded by distracter letters of similar appearance. Targets and distracters were displayed at 8° and 10° of visual angle from the fixation point (eccentricity, and target-distracter spacing was 2°, 3°, 4°, 5°, 6°, 7° or 8° of visual angle. Eccentricity and target-distracter spacing were randomly varied. Accuracy was defined as the proportion of correctly identified targets. Critical spacing was defined as the spacing at which target identification accuracy began to deteriorate, and was assessed at viewing eccentricities of 8° and 10°. Schizophrenia patients were less accurate and showed a larger critical spacing than healthy individuals. These results indicate that crowding is stronger and sensory processing of information in the visual periphery is impaired in schizophrenia. This is in line with previous reports of preferential magnocellular dysfunction in schizophrenia. Thus, deficits in peripheral vision may account for perceptual alterations and contribute to cognitive dysfunction in schizophrenia.

  7. The allocation of attention and working memory in visual crowding.

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    Bacigalupo, Felix; Luck, Steven J

    2015-06-01

    When the distance between a visual target and nearby flankers falls below a critical distance, target discrimination declines precipitously. This is called "crowding." Many researchers have proposed that selective attention plays a role in crowding. However, although some research has examined the effects of directing attention toward versus away from the targets, no previous research has assessed how attentional allocation varies as a function of target-flanker distance in crowding. Here, we used ERPs to assess the operation of attention during crowding, focusing on the attention-related N2pc component. We used a typical crowding task in which participants were asked to report the category (vowel/consonant) of a lateralized target letter flanked by distractor letters at different distances. We tested the hypothesis that attention fails when the target-flanker distance becomes too small for attention to operate effectively. Consistent with this hypothesis, we found that N2pc amplitude was maximal at intermediate target-flanker distances and decreased substantially when crowding became severe. In addition, we examined the sustained posterior contralateral negativity (SPCN), which reflects the amount of information being maintained in working memory. Unlike the N2pc component, the SPCN increased in amplitude at small target-flanker distances, suggesting that observers stored information about the target and flankers in working memory when attention failed to select the target. Together, the N2pc and SPCN results suggest that attention and working memory play distinctive roles in crowding: Attention operates to minimize interference from the flankers at intermediate target-flanker distances, whereas working memory may be recruited when attention fails to select the target at small target-flanker distances.

  8. A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding.

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    Huurneman, Bianca; Boonstra, F Nienke; Cox, Ralf Fa; Cillessen, Antonius Hn; van Rens, Ger

    2012-07-23

    This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV): 1) children with NV, 2) visually impaired (VI) children and adults and 3) children with cerebral visual impairment (CVI). The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding. Three electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid), and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions. Children with normal vision show an extent of contour interaction over an area 1.5-3× as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1-2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN) show interaction areas that are 2× larger than those seen adults with NV. The magnitude of the crowding effect is also 2× as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3× the size of that experienced by adults with NV. The methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to compare crowding ratios and it shows that charts with 50

  9. The Effect of Aging and Attention on Visual Crowding and Surround Suppression of Perceived Contrast Threshold.

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    Malavita, Menaka S; Vidyasagar, Trichur R; McKendrick, Allison M

    2017-02-01

    The purpose of this study was to study how, in midperipheral vision, aging affects visual processes that interfere with target detection (crowding and surround suppression) and to determine whether the performance on such tasks are related to visuospatial attention as measured by visual search. We investigated the effect of aging on crowding and suppression in detection of a target in peripheral vision, using different types of flanking stimuli. Both thresholds were also obtained while varying the position of the flanker (placed inside or outside of target, relative to fixation). Crowding thresholds were also estimated with spatial uncertainty (jitter). Additionally, we included a visual search task comprising Gabor stimuli to investigate whether performance is related to top-down attention. Twenty young adults (age, 18-32 years; mean age, 26.1 years; 10 males) and 19 older adults (age, 60-74 years; mean age, 70.3 years; 10 males) participated in the study. Older adults showed more surround suppression than the young (F[1,37] = 4.21; P attentional efficiency measured in the visual search task. There was also no significant correlation between crowding and surround suppression. We show that aging does not affect visual crowding but does increase surround suppression of contrast, suggesting that crowding and surround suppression may be distinct visual phenomena. Furthermore, strengths of crowding and surround suppression did not correlate with each other nor could they be predicted by efficiency of visual search.

  10. The effect of colored crowding bars on the HOTV visual acuity test in amblyopic patients.

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    Ruttum, Mark S; Covert, Douglas J

    2008-08-01

    Colored versus black crowding bars surrounding a black optotype may induce a greater level of interest in visual acuity testing in young children. To evaluate the adequacy of colored bars for a satisfactory crowding effect in children with amblyopia, we compared visual acuity measurements using black versus red, green, or yellow bars. To choose the best color to compare with black, 53 patients with amblyopia were randomly assigned to 1 of 3 crowding bar colors. Subjects had the visual acuity of each eye measured with black HOTV optotypes and bars and then with black optotypes and either red, green, or yellow bars. In a second phase of the study red crowding bars were compared with black in a group of 48 different patients with amblyopia. The difference in logMAR visual acuity between amblyopic eyes tested with red versus black crowding bars was not statistically significant (mean visual acuities of -0.24 and -0.26, respectively; p = 0.315), but the difference was significant with either green (-0.30 and -0.34; p = 0.047) or yellow (-0.14 and -0.24; p = 0.0003). In the nonamblyopic eyes none of the colored crowding bars yielded significantly different visual acuity measurements compared with black. In the second phase of the study red crowding bars yielded an average of one letter worse visual acuity than black bars, but the difference was not statistically significant. Red crowding bars surrounding black optotypes are an acceptable alternative to black crowding bars for the measurement of visual acuity in amblyopic eyes.

  11. Can visco-elastic phase separation, macromolecular crowding and colloidal physics explain nuclear organisation?

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    Iborra, Francisco J

    2007-04-12

    The cell nucleus is highly compartmentalized with well-defined domains, it is not well understood how this nuclear order is maintained. Many scientists are fascinated by the different set of structures observed in the nucleus to attribute functions to them. In order to distinguish functional compartments from non-functional aggregates, I believe is important to investigate the biophysical nature of nuclear organisation. The various nuclear compartments can be divided broadly as chromatin or protein and/or RNA based, and they have very different dynamic properties. The chromatin compartment displays a slow, constrained diffusional motion. On the other hand, the protein/RNA compartment is very dynamic. Physical systems with dynamical asymmetry go to viscoelastic phase separation. This phase separation phenomenon leads to the formation of a long-lived interaction network of slow components (chromatin) scattered within domains rich in fast components (protein/RNA). Moreover, the nucleus is packed with macromolecules in the order of 300 mg/ml. This high concentration of macromolecules produces volume exclusion effects that enhance attractive interactions between macromolecules, known as macromolecular crowding, which favours the formation of compartments. In this paper I hypothesise that nuclear compartmentalization can be explained by viscoelastic phase separation of the dynamically different nuclear components, in combination with macromolecular crowding and the properties of colloidal particles. I demonstrate that nuclear structure can satisfy the predictions of this hypothesis. I discuss the functional implications of this phenomenon.

  12. Modeling, simulation and visual analysis of crowds a multidisciplinary perspective

    CERN Document Server

    Ali, Saad; Manocha, Dinesh; Shah, Mubarak

    2013-01-01

    Over the last several years there has been a growing interest in developing computational methodologies for modeling and analyzing movements and behaviors of 'crowds' of people. This interest spans several scientific areas that includes Computer Vision, Computer Graphics, and Pedestrian Evacuation Dynamics. Despite the fact that these different scientific fields are trying to model the same physical entity (i.e. a crowd of people), research ideas have evolved independently. As a result each discipline has developed techniques and perspectives that are characteristically their own.

  13. Crowded task performance in visually impaired children : Comparing magnifier and large print

    NARCIS (Netherlands)

    Huurneman, Bianca; Boonstra, F. Nienke; Verezen, Cornelis A.; Cillessen, Antonius H. N.; van Rens, Ger; Cox, Ralf F. A.

    This study compares the influence of two different types of magnification (magnifier versus large print) on crowded near vision task performance. Fifty-eight visually impaired children aged 4-8 years participated. Participants were divided in two groups, matched on age and near visual acuity (NVA):

  14. Explaining effervescence: Investigating the relationship between shared social identity and positive experience in crowds.

    Science.gov (United States)

    Hopkins, Nick; Reicher, Stephen D; Khan, Sammyh S; Tewari, Shruti; Srinivasan, Narayanan; Stevenson, Clifford

    2016-01-01

    We investigated the intensely positive emotional experiences arising from participation in a large-scale collective event. We predicted such experiences arise when those attending a collective event are (1) able to enact their valued collective identity and (2) experience close relations with other participants. In turn, we predicted both of these to be more likely when participants perceived crowd members to share a common collective identity. We investigated these predictions in a survey of pilgrims (N = 416) attending a month-long Hindu pilgrimage festival in north India. We found participants' perceptions of a shared identity amongst crowd members had an indirect effect on their positive experience at the event through (1) increasing participants' sense that they were able to enact their collective identity and (2) increasing the sense of intimacy with other crowd members. We discuss the implications of these data for how crowd emotion should be conceptualised.

  15. Patterns in emergency-department arrivals and length of stay: Input for visualizations of crowding

    DEFF Research Database (Denmark)

    Hertzum, Morten

    2016-01-01

    Crowding is common in emergency departments (EDs) and increases the risk of medical errors, patient dissatisfaction, and clinician stress. The aim of this study is to investigate patterns in patient visits and bottlenecks in ED work in order to discuss the prospects of visualizing such patterns...

  16. Crowded visual search in children with normal vision and children with visual impairment.

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    Huurneman, Bianca; Cox, Ralf F A; Vlaskamp, Björn N S; Boonstra, F Nienke

    2014-03-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n=11), children with visual impairment without nystagmus ([VI-nys], n=11), and children with VI with accompanying nystagmus ([VI+nys], n=26). Exclusion criteria for children with VI were: multiple impairments and visual acuity poorer than 20/400 or better than 20/50. Three search conditions were presented: a row with homogeneous distractors, a matrix with homogeneous distractors, and a matrix with heterogeneous distractors. Element spacing was manipulated in 5 steps from 2 to 32 minutes of arc. Symbols were sized 2 times the threshold acuity to guarantee visibility for the VI groups. During simple row and matrix search with homogeneous distractors children in the VI+nys group were less accurate than children with NV at smaller spacings. Group differences were even more pronounced during matrix search with heterogeneous distractors. Search times were longer in children with VI compared to children with NV. The more extended impairments during serial search reveal greater dependence on oculomotor control during serial compared to parallel search. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Visual acuity, crowding, and stereo-vision are linked in children with and without amblyopia.

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    Greenwood, John A; Tailor, Vijay K; Sloper, John J; Simmers, Anita J; Bex, Peter J; Dakin, Steven C

    2012-11-15

    During development, the presence of strabismus and anisometropia frequently leads to amblyopia, a visual disorder characterized by interocular acuity differences. Although additional deficits in contrast sensitivity, crowding (the impaired recognition of closely spaced objects), and stereoacuity are common, the relationship between these abilities is unclear. We measured the covariation between these four abilities in children 4 to 9 years of age (n = 72) with strabismus, anisometropia, or mixed strabismus/anisometropia, and unaffected controls. Children reported the orientation of a target (a modified "Pac-Man," similar to Landolt-C stimuli) using four "ghosts" as references. Using a modified staircase procedure we measured threshold size (acuity), contrast detection, foveal crowding (the minimum separation between target and ghost-flankers supporting accurate identification), and stereoacuity (with random-dot stereogram ghosts). Group averages revealed significant interocular differences (IODs) in acuity for all three clinical groups (0.2-0.3 log minutes), and significant crowding IODs for the strabismic and mixed groups (0.6 and 0.4°, respectively). Nonetheless, crowding IODs were correlated with acuity IODs in all four groups (r values between 0.43 and 0.59 and P stereo-blindness (most common in strabismic and mixed groups) was associated with a significant increase in IODs for both acuity and crowding (each P stereo-vision. We suggest that the deficits derived from strabismus and anisometropia lay along a continuum with abilities observed during normal development.

  18. Crowded task performance in visually impaired children: magnifier versus large print.

    Science.gov (United States)

    Huurneman, Bianca; Boonstra, F Nienke; Verezen, Cornelis A; Cillessen, Antonius H N; van Rens, Ger; Cox, Ralf F A

    2013-07-01

    This study compares the influence of two different types of magnification (magnifier versus large print) on crowded near vision task performance. Fifty-eight visually impaired children aged 4-8 years participated. Participants were divided in two groups, matched on age and near visual acuity (NVA): [1] the magnifier group (4-6 year olds [n = 13] and 7-8 year olds [n = 19]), and [2] the large print group (4-6 year olds [n = 12] and 7-8 year olds [n = 14]). At baseline, single and crowded Landolt C acuity were measured at 40 cm without magnification. Crowded near vision was measured again with magnification. A 90 mm diameter dome magnifier was chosen to avoid measuring the confounding effect of navigational skills. The magnifier provided 1.7× magnification and the large print provided 1.8× magnification. Performance measures: [1] NVA without magnification at 40 cm, [2] near vision with magnification, and [3] response time. Working distance was monitored. There was no difference in performance between the two types of magnification for the 4-6 year olds and the 7-8 year olds (p's = .291 and .246, respectively). Average NVA in the 4-6 year old group was 0.95 logMAR without and 0.42 logMAR with magnification (p children with a range of visual acuities on a crowded near vision task. Visually impaired children with stronger crowding effects showed larger improvements when working with magnification.

  19. When apperceptive agnosia is explained by a deficit of primary visual processing.

    Science.gov (United States)

    Serino, Andrea; Cecere, Roberto; Dundon, Neil; Bertini, Caterina; Sanchez-Castaneda, Cristina; Làdavas, Elisabetta

    2014-03-01

    Visual agnosia is a deficit in shape perception, affecting figure, object, face and letter recognition. Agnosia is usually attributed to lesions to high-order modules of the visual system, which combine visual cues to represent the shape of objects. However, most of previously reported agnosia cases presented visual field (VF) defects and poor primary visual processing. The present case-study aims to verify whether form agnosia could be explained by a deficit in basic visual functions, rather that by a deficit in high-order shape recognition. Patient SDV suffered a bilateral lesion of the occipital cortex due to anoxia. When tested, he could navigate, interact with others, and was autonomous in daily life activities. However, he could not recognize objects from drawings and figures, read or recognize familiar faces. He was able to recognize objects by touch and people from their voice. Assessments of visual functions showed blindness at the centre of the VF, up to almost 5°, bilaterally, with better stimulus detection in the periphery. Colour and motion perception was preserved. Psychophysical experiments showed that SDV's visual recognition deficits were not explained by poor spatial acuity or by the crowding effect. Rather a severe deficit in line orientation processing might be a key mechanism explaining SDV's agnosia. Line orientation processing is a basic function of primary visual cortex neurons, necessary for detecting "edges" of visual stimuli to build up a "primal sketch" for object recognition. We propose, therefore, that some forms of visual agnosia may be explained by deficits in basic visual functions due to widespread lesions of the primary visual areas, affecting primary levels of visual processing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.; Cox, R.F.A.; Cillessen, A.H.N.; van Rens, G.H.M.B.

    2012-01-01

    Background: This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy

  1. A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding.

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.; Cox, R.F.; Cillessen, A.H.; Rens, G. van

    2012-01-01

    BACKGROUND: This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy

  2. Visual cognition: rats compare shapes among the crowd.

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    Cruz-Martín, Alberto; Huberman, Andrew D

    2012-01-10

    Rats can discriminate simple shapes visually, even if they are moved around, made smaller, or partially covered up; the strategy they use may help shed light on human brain mechanisms for discriminating complex features, such as faces. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Cholinergic enhancement reduces orientation-specific surround suppression but not visual crowding

    Directory of Open Access Journals (Sweden)

    Anna A. Kosovicheva

    2012-09-01

    Full Text Available Acetylcholine (ACh reduces the spatial spread of excitatory fMRI responses in early visual cortex and the receptive field sizes of V1 neurons. We investigated the perceptual consequences of these physiological effects of ACh with surround suppression and crowding, two tasks that involve spatial interactions between visual field locations. Surround suppression refers to the reduction in perceived stimulus contrast by a high-contrast surround stimulus. For grating stimuli, surround suppression is selective for the relative orientations of the center and surround, suggesting that it results from inhibitory interactions in early visual cortex. Crowding refers to impaired identification of a peripheral stimulus in the presence of flankers and is thought to result from excessive integration of visual features. We increased synaptic ACh levels by administering the cholinesterase inhibitor donepezil to healthy human subjects in a placebo-controlled, double-blind design. In Exp. 1, we measured surround suppression of a central grating using a contrast discrimination task with three conditions: 1 surround grating with the same orientation as the center (parallel, 2 surround orthogonal to the center, or 3 no surround. Contrast discrimination thresholds were higher in the parallel than in the orthogonal condition, demonstrating orientation-specific surround suppression (OSSS. Cholinergic enhancement reduced thresholds only in the parallel condition, thereby reducing OSSS. In Exp. 2, subjects performed a crowding task in which they reported the identity of a peripheral letter flanked by letters on either side. We measured the critical spacing between the target and flanking letters that allowed reliable identification. Cholinergic enhancement had no effect on critical spacing. Our findings suggest that ACh reduces spatial interactions in tasks involving segmentation of visual field locations but that these effects may be limited to early visual cortical

  4. Peripheral Vision of Youths with Low Vision: Motion Perception, Crowding, and Visual Search

    Science.gov (United States)

    Tadin, Duje; Nyquist, Jeffrey B.; Lusk, Kelly E.; Corn, Anne L.; Lappin, Joseph S.

    2012-01-01

    Purpose. Effects of low vision on peripheral visual function are poorly understood, especially in children whose visual skills are still developing. The aim of this study was to measure both central and peripheral visual functions in youths with typical and low vision. Of specific interest was the extent to which measures of foveal function predict performance of peripheral tasks. Methods. We assessed central and peripheral visual functions in youths with typical vision (n = 7, ages 10–17) and low vision (n = 24, ages 9–18). Experimental measures used both static and moving stimuli and included visual crowding, visual search, motion acuity, motion direction discrimination, and multitarget motion comparison. Results. In most tasks, visual function was impaired in youths with low vision. Substantial differences, however, were found both between participant groups and, importantly, across different tasks within participant groups. Foveal visual acuity was a modest predictor of peripheral form vision and motion sensitivity in either the central or peripheral field. Despite exhibiting normal motion discriminations in fovea, motion sensitivity of youths with low vision deteriorated in the periphery. This contrasted with typically sighted participants, who showed improved motion sensitivity with increasing eccentricity. Visual search was greatly impaired in youths with low vision. Conclusions. Our results reveal a complex pattern of visual deficits in peripheral vision and indicate a significant role of attentional mechanisms in observed impairments. These deficits were not adequately captured by measures of foveal function, arguing for the importance of independently assessing peripheral visual function. PMID:22836766

  5. Crowding in central vision in normally sighted and visually impaired [corrected] children aged 4 to 8 years: the influence of age and test design.

    Science.gov (United States)

    Huurneman, Bianca; Boonstra, F Nienke; Cillessen, Antonius H N; van Rens, Ger; Cox, Ralf F A

    2012-06-01

    To investigate crowding ratios in children with a visual impairment due to ocular disease (n = 58) and normally sighted children (n = 75) aged 4 to 8 years using several variants of two clinically available tests with different optotype spacing (fixed or proportional to the optotype size). Crowding ratios, calculated by dividing the single acuity by the linear acuity, were measured binocularly with the C-test and the LH line chart. Ratios >1.00 indicate crowding. The charts with fixed spacing revealed significantly higher crowding ratios for visually impaired children than normally sighted children (both for measurements at 40 cm and 5 m). The age-related reduction of the crowding ratios seen in normally sighted children when tested with near-vision charts with fixed spacing was not present in the visually impaired group. Visually impaired children with nystagmus showed higher crowding ratios than visually impaired children without nystagmus. The chart with proportional intersymbol spacing (ISS) did not reveal differences between the normally sighted and visually impaired children; nor did it show group, age, or nystagmus effects. Visually impaired children showed higher crowding ratios than normally sighted children when measured with charts with fixed ISS. This study illustrates that test design and target/flanker interference as a manifestation of crowding are critical issues to bear in mind when assessing crowding ratios in children.

  6. Quality improvement collaboratives and the wisdom of crowds: spread explained by perceived success at group level.

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    Dückers, Michel L A; Groenewegen, Peter P; Wagner, Cordula

    2014-07-22

    Many studies have been conducted to evaluate the impact of quality improvement collaboratives (QICs) on the quality of healthcare. This article addresses an underexplored topic, namely the use of QICs as 'intentional spread strategy.' Its objective is to predict the dissemination of projects within hospitals participating in a change programme based on several QICs. We tested whether the average project success at QIC level (based on opinions of individual project team leaders) explains the dissemination of projects one year later. After one year, 148 project team leaders of 16 hospitals participating in the two-year programme were asked to rate the success of their improvement project on a scale from 1 to 10. At the end of the second year, the programme coordinator of each hospital provided information on the second-year dissemination. Average success scores and dissemination statistics were calculated for each QIC (N = 12). The non-parametric correlation between team leader judgment and dissemination rate at QIC level is 0.73 (P < 0.01). Previous work, focusing on the team and hospital level, showed which factors contributed to local success stories. It also illustrated how successes play a role in dissemination processes within programme hospitals. The current study suggests that we cannot ignore the extent to which the dissemination potential of individual projects is defined by their QIC. Aggregated team leader judgments at the QIC level might predict the future dissemination in participating organizations. The findings, however, need to be replicated in larger, independent samples.

  7. The Problems and Challenges of Managing Crowd Sourced Audio-Visual Evidence

    Directory of Open Access Journals (Sweden)

    Harjinder Singh Lallie

    2014-04-01

    Full Text Available A number of recent incidents, such as the Stanley Cup Riots, the uprisings in the Middle East and the London riots have demonstrated the value of crowd sourced audio-visual evidence wherein citizens submit audio-visual footage captured on mobile phones and other devices to aid governmental institutions, responder agencies and law enforcement authorities to confirm the authenticity of incidents and, in the case of criminal activity, to identify perpetrators. The use of such evidence can present a significant logistical challenge to investigators, particularly because of the potential size of data gathered through such mechanisms and the added problems of time-lining disparate sources of evidence and, subsequently, investigating the incident(s. In this paper we explore this problem and, in particular, outline the pressure points for an investigator. We identify and explore a number of particular problems related to the secure receipt of the evidence, imaging, tagging and then time-lining the evidence, and the problem of identifying duplicate and near duplicate items of audio-visual evidence.

  8. Are individual differences in reading speed related to extrafoveal visual acuity and crowding?

    Science.gov (United States)

    Frömer, Romy; Dimigen, Olaf; Niefind, Florian; Krause, Niels; Kliegl, Reinhold; Sommer, Werner

    2015-01-01

    Readers differ considerably in their speed of self-paced reading. One factor known to influence fixation durations in reading is the preprocessing of words in parafoveal vision. Here we investigated whether individual differences in reading speed or the amount of information extracted from upcoming words (the preview benefit) can be explained by basic differences in extrafoveal vision--i.e., the ability to recognize peripheral letters with or without the presence of flanking letters. Forty participants were given an adaptive test to determine their eccentricity thresholds for the identification of letters presented either in isolation (extrafoveal acuity) or flanked by other letters (crowded letter recognition). In a separate eye-tracking experiment, the same participants read lists of words from left to right, while the preview of the upcoming words was manipulated with the gaze-contingent moving window technique. Relationships between dependent measures were analyzed on the observational level and with linear mixed models. We obtained highly reliable estimates both for extrafoveal letter identification (acuity and crowding) and measures of reading speed (overall reading speed, size of preview benefit). Reading speed was higher in participants with larger uncrowded windows. However, the strength of this relationship was moderate and it was only observed if other sources of variance in reading speed (e.g., the occurrence of regressive saccades) were eliminated. Moreover, the size of the preview benefit--an important factor in normal reading--was larger in participants with better extrafoveal acuity. Together, these results indicate a significant albeit moderate contribution of extrafoveal vision to individual differences in reading speed.

  9. Are individual differences in reading speed related to extrafoveal visual acuity and crowding?

    Directory of Open Access Journals (Sweden)

    Romy Frömer

    Full Text Available Readers differ considerably in their speed of self-paced reading. One factor known to influence fixation durations in reading is the preprocessing of words in parafoveal vision. Here we investigated whether individual differences in reading speed or the amount of information extracted from upcoming words (the preview benefit can be explained by basic differences in extrafoveal vision--i.e., the ability to recognize peripheral letters with or without the presence of flanking letters. Forty participants were given an adaptive test to determine their eccentricity thresholds for the identification of letters presented either in isolation (extrafoveal acuity or flanked by other letters (crowded letter recognition. In a separate eye-tracking experiment, the same participants read lists of words from left to right, while the preview of the upcoming words was manipulated with the gaze-contingent moving window technique. Relationships between dependent measures were analyzed on the observational level and with linear mixed models. We obtained highly reliable estimates both for extrafoveal letter identification (acuity and crowding and measures of reading speed (overall reading speed, size of preview benefit. Reading speed was higher in participants with larger uncrowded windows. However, the strength of this relationship was moderate and it was only observed if other sources of variance in reading speed (e.g., the occurrence of regressive saccades were eliminated. Moreover, the size of the preview benefit--an important factor in normal reading--was larger in participants with better extrafoveal acuity. Together, these results indicate a significant albeit moderate contribution of extrafoveal vision to individual differences in reading speed.

  10. The Face in the Crowd Effect Unconfounded: Happy Faces, Not Angry Faces, Are More Efficiently Detected in Single- and Multiple-Target Visual Search Tasks

    Science.gov (United States)

    Becker, D. Vaughn; Anderson, Uriah S.; Mortensen, Chad R.; Neufeld, Samantha L.; Neel, Rebecca

    2011-01-01

    Is it easier to detect angry or happy facial expressions in crowds of faces? The present studies used several variations of the visual search task to assess whether people selectively attend to expressive faces. Contrary to widely cited studies (e.g., Ohman, Lundqvist, & Esteves, 2001) that suggest angry faces "pop out" of crowds, our review of…

  11. A systematic review on ‘Foveal Crowding’ in visually impaired children and perceptual learning as a method to reduce Crowding

    Science.gov (United States)

    2012-01-01

    Background This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV): 1) children with NV, 2) visually impaired (VI) children and adults and 3) children with cerebral visual impairment (CVI). The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding. Methods Three electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid), and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions. Results Children with normal vision show an extent of contour interaction over an area 1.5–3× as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1–2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN) show interaction areas that are 2× larger than those seen adults with NV. The magnitude of the crowding effect is also 2× as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3× the size of that experienced by adults with NV. Conclusions The methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to compare crowding ratios

  12. A systematic review on ‘Foveal Crowding’ in visually impaired children and perceptual learning as a method to reduce Crowding

    Directory of Open Access Journals (Sweden)

    Huurneman Bianca

    2012-07-01

    Full Text Available Abstract Background This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV: 1 children with NV, 2 visually impaired (VI children and adults and 3 children with cerebral visual impairment (CVI. The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding. Methods Three electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid, and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions. Results Children with normal vision show an extent of contour interaction over an area 1.5–3× as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1–2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN show interaction areas that are 2× larger than those seen adults with NV. The magnitude of the crowding effect is also 2× as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3× the size of that experienced by adults with NV. Conclusions The methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to

  13. Age-related changes in crowding and reading speed.

    Science.gov (United States)

    Liu, Rong; Patel, Bhavika N; Kwon, MiYoung

    2017-08-15

    Crowding, the inability to recognize objects in clutter, is known to play a role in developmental changes in reading speed. Here, we investigated whether crowding also plays a role in age-related changes in reading speed. We recruited 18 young (mean age: 22.6 ± 3.5; range: 18~31) and 21 older adults (mean age: 58.2 ± 7.0; range: 50~73) with normal vision. Reading speed was measured with short blocks of text. The degree of crowding was determined by measuring crowding zone (the distance between a target and flankers required to yield a criterion recognition accuracy) and the size of the visual span (an uncrowded window in the visual field within which letters can be recognizable reliably). Measurements were made across the central 16-degree visual field using letter-recognition tasks. Our results showed that, compared to young adults, older adults exhibited significantly slower reading speed (a decrease by 30%) and larger crowding: an enlargement of crowding zone (an increase by 31%) and shrinkage of the visual span (a decrease by 6.25 bits). We also observed significant correlations between reading speed and each of the crowding measures. Our results suggest that crowding increases with age. Age-related changes in crowding may in part explain slower reading in older adults.

  14. Crowd Sourcing.

    Science.gov (United States)

    Baum, Neil

    2016-01-01

    The Internet has contributed new words and slang to our daily vernacular. A few terms, such as tweeting, texting, sexting, blogging, and googling, have become common in most vocabularies and in many languages, and are now included in the dictionary. A new buzzword making the rounds in industry is crowd sourcing, which involves outsourcing an activity, task, or problem by sending it to people or groups outside a business or a practice. Crowd sourcing allows doctors and practices to tap the wisdom of many instead of relying only on the few members of their close-knit group. This article defines "crowd sourcing," offers examples, and explains how to get started with this approach that can increase your ability to finish a task or solve problems that you don't have the time or expertise to accomplish.

  15. [To explain is to narrate. How to visualize scientific data].

    Science.gov (United States)

    Hawtin, Nigel

    2014-01-01

    When you try to appeal a vast ranging audience, as it occurs at the New Scientist that addresses scientists as well as the general public, your scientific visual explainer must be succinct, clear, accurate and easily understandable. In order to reach this goal, your message should provide only the main data, the ones that allow you to balance information and clarity: information should be put into context and all the extra details should be cut down. It is very important, then, to know well both your audience and the subject you are going to describe, as graphic masters of the past, like William Playfair and Charles Minard, have taught us. Moreover, you should try to engage your reader connecting the storytelling power of words and the driving force of the graphics: colours, visual elements, typography. To be effective, in fact, an infographic should not only be truthful and functional, but also elegant, having style and legibility.

  16. Looking back at the stare-in-the-crowd effect: staring eyes do not capture attention in visual search.

    Science.gov (United States)

    Cooper, Robbie M; Law, Anna S; Langton, Stephen R H

    2013-05-17

    The stare-in-the crowd effect refers to the finding that a visual search for a target of staring eyes among averted-eyes distracters is more efficient than the search for an averted-eyes target among staring distracters. This finding could indicate that staring eyes are prioritized in the processing of the search array so that attention is more likely to be directed to their location than to any other. However, visual search is a complex process, which not only depends upon the properties of the target, but also the similarity between the target of the search and the distractor items and between the distractor items themselves. Across five experiments, we show that the search asymmetry diagnostic of the stare-in-the-crowd effect is more likely to be the result of a failure to control for the similarity among distracting items between the two critical search conditions rather than any special attention-grabbing property of staring gazes. Our results suggest that, contrary to results reported in the literature, staring gazes are not prioritized by attention in visual search.

  17. Torso Crowds

    NARCIS (Netherlands)

    Stüvel, S.A.; Magnenat-Thalmann, Nadia; Thalmann, Daniel; van der Stappen, A.F.; Egges, J.

    2017-01-01

    We present a novel dense crowd simulation method. In real crowds of high density, people manoeuvring the crowd need to twist their torso to pass between others. Our proposed method employs capsule-shaped agents, which enables us to plan such torso orientations. Contrary to other crowd simulation

  18. Perceived Positions Determine Crowding

    Science.gov (United States)

    Maus, Gerrit W.; Fischer, Jason; Whitney, David

    2011-01-01

    Crowding is a fundamental bottleneck in object recognition. In crowding, an object in the periphery becomes unrecognizable when surrounded by clutter or distractor objects. Crowding depends on the positions of target and distractors, both their eccentricity and their relative spacing. In all previous studies, position has been expressed in terms of retinal position. However, in a number of situations retinal and perceived positions can be dissociated. Does retinal or perceived position determine the magnitude of crowding? Here observers performed an orientation judgment on a target Gabor patch surrounded by distractors that drifted toward or away from the target, causing an illusory motion-induced position shift. Distractors in identical physical positions led to worse performance when they drifted towards the target (appearing closer) versus away from the target (appearing further). This difference in crowding corresponded to the difference in perceived positions. Further, the perceptual mislocalization was necessary for the change in crowding, and both the mislocalization and crowding scaled with drift speed. The results show that crowding occurs after perceived positions have been assigned by the visual system. Crowding does not operate in a purely retinal coordinate system; perceived positions need to be taken into account. PMID:21629690

  19. What explains health in persons with visual impairment?

    Science.gov (United States)

    Leissner, Juliane; Coenen, Michaela; Froehlich, Stephan; Loyola, Danny; Cieza, Alarcos

    2014-05-03

    Visual impairment is associated with important limitations in functioning. The International Classification of Functioning, Disability and Health (ICF) adopted by the World Health Organisation (WHO) relies on a globally accepted framework for classifying problems in functioning and the influence of contextual factors. Its comprehensive perspective, including biological, individual and social aspects of health, enables the ICF to describe the whole health experience of persons with visual impairment. The objectives of this study are (1) to analyze whether the ICF can be used to comprehensively describe the problems in functioning of persons with visual impairment and the environmental factors that influence their lives and (2) to select the ICF categories that best capture self-perceived health of persons with visual impairment. Data from 105 persons with visual impairment were collected, including socio-demographic data, vision-related data, the Extended ICF Checklist and the visual analogue scale of the EuroQoL-5D, to assess self-perceived health. Descriptive statistics and a Group Lasso regression were performed. The main outcome measures were functioning defined as impairments in Body functions and Body structures, limitations in Activities and restrictions in Participation, influencing Environmental factors and self-perceived health. In total, 120 ICF categories covering a broad range of Body functions, Body structures, aspects of Activities and Participation and Environmental factors were identified. Thirteen ICF categories that best capture self-perceived health were selected based on the Group Lasso regression. While Activities-and-Participation categories were selected most frequently, the greatest impact on self-perceived health was found in Body-functions categories. The ICF can be used as a framework to comprehensively describe the problems of persons with visual impairment and the Environmental factors which influence their lives. There are plenty of

  20. Crowding in central vision in normally sighted and visually impaired [corrected] children aged 4 to 8 years: the influence of age and test design.

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.; Cillessen, A.H.N.; Rens, G. van; Cox, R.F.

    2012-01-01

    BACKGROUND/AIMS: To investigate crowding ratios in children with a visual impairment due to ocular disease (n = 58) and normally sighted children (n = 75) aged 4 to 8 years using several variants of two clinically available tests with different optotype spacing (fixed or proportional to the optotype

  1. Semantic priming from crowded words.

    Science.gov (United States)

    Yeh, Su-Ling; He, Sheng; Cavanagh, Patrick

    2012-06-01

    Vision in a cluttered scene is extremely inefficient. This damaging effect of clutter, known as crowding, affects many aspects of visual processing (e.g., reading speed). We examined observers' processing of crowded targets in a lexical decision task, using single-character Chinese words that are compact but carry semantic meaning. Despite being unrecognizable and indistinguishable from matched nonwords, crowded prime words still generated robust semantic-priming effects on lexical decisions for test words presented in isolation. Indeed, the semantic-priming effect of crowded primes was similar to that of uncrowded primes. These findings show that the meanings of words survive crowding even when the identities of the words do not, suggesting that crowding does not prevent semantic activation, a process that may have evolved in the context of a cluttered visual environment.

  2. Nonconscious Influences from Emotional Faces: A Comparison of Visual Crowding, Masking, and Continuous Flash Suppression

    Directory of Open Access Journals (Sweden)

    Nathan eFaivre

    2012-05-01

    Full Text Available In the study of nonconscious processing, different methods have been used in order to renderstimuli invisible. While their properties are well described, the level at which they disruptnonconscious processing remains unclear. Yet, such accurate estimation of the depth ofnonconscious processes is crucial for a clear differentiation between conscious and nonconsciouscognition. Here, we compared the processing of facial expressions rendered invisible through gazecontingentcrowding (GCC, masking, and continuous flash suppression (CFS, three techniquesrelying on different properties of the visual system. We found that both pictures and videos of happyfaces suppressed from awareness by GCC were processed such as to bias subsequent preferencejudgments. The same stimuli manipulated with visual masking and CFS did not bias significantlypreference judgments, although they were processed such as to elicit perceptual priming. Asignificant difference in preference bias was found between GCC and CFS, but not between GCCand masking. These results provide new insights regarding the nonconscious impact of emotionalfeatures, and highlight the need for rigorous comparisons between the different methods employedto prevent perceptual awareness.

  3. The User Puzzle—Explaining the Interaction with Visual Analytics Systems.

    Science.gov (United States)

    Pohl, M; Smuc, M; Mayr, E

    2012-12-01

    Visual analytics emphasizes the interplay between visualization, analytical procedures performed by computers and human perceptual and cognitive activities. Human reasoning is an important element in this context. There are several theories in psychology and HCI explaining open-ended and exploratory reasoning. Five of these theories (sensemaking theories, gestalt theories, distributed cognition, graph comprehension theories and skill-rule-knowledge models) are described in this paper. We discuss their relevance for visual analytics. In order to do this more systematically, we developed a schema of categories relevant for visual analytics research and evaluation. All these theories have strengths but also weaknesses in explaining interaction with visual analytics systems. A possibility to overcome the weaknesses would be to combine two or more of these theories.

  4. Realistic Crowd Simulation with Density-Based Path Planning

    NARCIS (Netherlands)

    van Toll, W.G.; Cook IV, A.F.; Geraerts, R.J.

    2012-01-01

    Virtual characters in games and simulations often need to plan visually convincing paths through a crowded environment. This paper describes how crowd density information can be used to guide a large number of characters through a crowded environment. Crowd density information helps characters avoid

  5. Real-Time Density-Based Crowd Simulation

    NARCIS (Netherlands)

    van Toll, W.G.|info:eu-repo/dai/nl/35269288X; Cook IV, A.F.; Geraerts, R.J.|info:eu-repo/dai/nl/304830291

    2012-01-01

    Virtual characters in games and simulations often need to plan visually convincing paths through a crowded environment. This paper describes how crowd density information can be used to guide a large number of characters through a crowded environment. Crowd density information helps characters avoid

  6. Crowdedness mediates the effect of social identification on positive emotion in a crowd: a survey of two crowd events.

    Science.gov (United States)

    Novelli, David; Drury, John; Reicher, Stephen; Stott, Clifford

    2013-01-01

    Exposure to crowding is said to be aversive, yet people also seek out and enjoy crowded situations. We surveyed participants at two crowd events to test the prediction of self-categorization theory that variable emotional responses to crowding are a function of social identification with the crowd. In data collected from participants who attended a crowded outdoor music event (n = 48), identification with the crowd predicted feeling less crowded; and there was an indirect effect of identification with the crowd on positive emotion through feeling less crowded. Identification with the crowd also moderated the relation between feeling less crowded and positive emotion. In data collected at a demonstration march (n = 112), identification with the crowd predicted central (most dense) location in the crowd; and there was an indirect effect of identification with the crowd on positive emotion through central location in the crowd. Positive emotion in the crowd also increased over the duration of the crowd event. These findings are in line with the predictions of self-categorization theory. They are inconsistent with approaches that suggest that crowding is inherently aversive; and they cannot easily be explained through the concept of 'personal space'.

  7. Crowdedness mediates the effect of social identification on positive emotion in a crowd: a survey of two crowd events.

    Directory of Open Access Journals (Sweden)

    David Novelli

    Full Text Available Exposure to crowding is said to be aversive, yet people also seek out and enjoy crowded situations. We surveyed participants at two crowd events to test the prediction of self-categorization theory that variable emotional responses to crowding are a function of social identification with the crowd. In data collected from participants who attended a crowded outdoor music event (n = 48, identification with the crowd predicted feeling less crowded; and there was an indirect effect of identification with the crowd on positive emotion through feeling less crowded. Identification with the crowd also moderated the relation between feeling less crowded and positive emotion. In data collected at a demonstration march (n = 112, identification with the crowd predicted central (most dense location in the crowd; and there was an indirect effect of identification with the crowd on positive emotion through central location in the crowd. Positive emotion in the crowd also increased over the duration of the crowd event. These findings are in line with the predictions of self-categorization theory. They are inconsistent with approaches that suggest that crowding is inherently aversive; and they cannot easily be explained through the concept of 'personal space'.

  8. Visual impairment and blindness in spanish adults: geographic inequalities are not explained by age or education.

    Science.gov (United States)

    Rius, Anna; Artazcoz, Lucía; Guisasola, Laura; Benach, Joan

    2014-01-01

    The objectives of this study were to examine for the first time the prevalence of visual impairment and blindness among adults in Spain, to explore regional differences, and to assess whether they may vary as a function of sex or be explained by age and individual or regional socioeconomic position. Data were obtained from the 2008 Spanish Survey on Disability, Personal Autonomy, and Dependency Situations, a cross-sectional survey based on a representative sample of the noninstitutionalized population of Spain. The sample was composed of 213 626 participants aged ≥15 years (103 093 men and 110 533 women); 360 were blind (160 men and 200 women), 4048 had near visual impairment (1397 men and 2651 women), and 4034 had distance visual impairment (1445 men and 2589 women). The prevalence of near and distance visual impairment was calculated for each region. Multiple logistic regression models were fitted to calculate odds ratios and 95% confidence intervals. All analyses were stratified by sex. Visual impairment was based on 3 questions aimed at identifying blindness and near and distance visual impairment. The prevalence (percentage) of blindness was 0.17 (men, 0.16; women, 0.18): 1.89 for near visual impairment (men, 1.36; women, 2.40), 1.89 for distance visual impairment (men, 1.40; women, 2.34), and 2.43 for any visual impairment (men, 1.81; women, 3.02). Regional inequalities in the prevalence of visual impairment were observed, correlated with regional income, and the prevalence was consistently higher among women than men. The magnitude of the inequalities remained after adjusting for age and educational level, and a north-to-south pattern of increasing prevalence was observed. Regional and sex inequalities in the prevalence of visual impairment and blindness were observed in Spain, with a north-to-south gradient of increasing prevalence that was not explained by age or individual educational level but was correlated with regional level of economic

  9. Crowd Theory and the Management of Crowds

    DEFF Research Database (Denmark)

    Borch, Christian

    2013-01-01

    Sociologists of policing and collective protest have made a plea for eradicating from police literature and training programmes which aim to provide guidelines for crowd management any references to classical crowd theory where crowds are depicted as irrational entities. Instead, these scholars...... suggest, rational conceptions of crowds should inform contemporary crowd management. This article questions this plea on two grounds. First, it demonstrates that there is no unidirectional connection between sociological crowd theory (whatever its content) and practical strategies for governing crowds....... The tactical polyvalence of crowd theory is illustrated by showing how the irrational conception of crowds has given rise to very different strategies for the management of crowds (urban reform programmes in the Progressive Era and Hitler’s mobilization strategies, respectively). Second, the article argues...

  10. Using facial emotional stimuli in visual search experiments: the arousal factor explains contradictory results.

    Science.gov (United States)

    Lundqvist, Daniel; Juth, Pernilla; Öhman, Arne

    2014-01-01

    For more than two decades, visual search experiments using pictures of emotional faces as stimuli have generated contradictory results. Evidence of a superior detection of angry faces compared to happy faces have been mixed with an equal amount of evidence in the opposite direction. In this article, we review this literature, and examine the hypothesis that the neglected stimulus factor of emotional arousal may explain these contradictory results. Through an extensive reanalysis of results from our own laboratory as well as from other researchers, we show that the arousal factor systematically influences the outcome of the reviewed visual search experiments, and may thus provide a key to the historical contradictions within this research field.

  11. To See (Like a Crowd

    Directory of Open Access Journals (Sweden)

    Hazem Ziada

    2015-07-01

    Full Text Available This paper explores the dynamics through which design drawings structure spatial strategies, particularly those with an agenda for socio-political change, while interrogating the drawings’ impacts on subjectivity. It dissects an early Soviet architectural drawing addressing the 1920s-30s' crowd-design-problem': using architectural space to generate a robust intersubjectivity in mass crowds. Revolutionary Soviet artists challenged inherited graphic regimes of viewing crowds from an alienating distance, proposing devices of 'immersion' to radically re-visualize mass crowds and re-conceptualize collectivity. Drawing on Suprematist compositions, the avant-garde Soviet Rationalist architects translated immersive principles from contemporary revolutionary art. The paper articulates the Rationalists’ alternative graphic framework which immerses the observer-cum-designer within crowd dynamics in a distinctively architectural way, while identifying its implications on spatial design: a space of undulating grounds, rhythmic choreographies and ‘textured’ visual fields. The paper also speculates on its implications redefining subjectivity; re-introducing emotion amongst the relations of production challenges canonical Historical Materialism.

  12. Poster: Observing change in crowded data sets in 3D space - Visualizing gene expression in human tissues

    KAUST Repository

    Rogowski, Marcin

    2013-03-01

    We have been confronted with a real-world problem of visualizing and observing change of gene expression between different human tissues. In this paper, we are presenting a universal representation space based on two-dimensional gel electrophoresis as opposed to force-directed layouts encountered most often in similar problems. We are discussing the methods we devised to make observing change more convenient in a 3D virtual reality environment. © 2013 IEEE.

  13. Crowd turbulence: the physics of crowd disasters

    OpenAIRE

    Helbing, Dirk; Johansson, Anders; Al-Abideen, Habib Z.

    2007-01-01

    The panic stampede is a serious concern during mass events like soccer championship games. Despite huge numbers of security forces and crowd control measures, hundreds of lives are lost in crowd disasters each year. An analysis of video recordings of the annual pilgrimage in Makkah reveals how high-density crowds develop to turbulent dynamics and earthquake-like eruptions, which is impossible to control.

  14. Can two established information models explain the information behaviour of visually impaired people seeking health and social care information?

    OpenAIRE

    Beverley, C.A.; Bath, P.A.; Barber, R.

    2007-01-01

    Purpose – The purpose of this study is to determine the extent to which two existing models of information behaviour could explain the information behaviour of visually impaired people seeking health and social care information.\\ud \\ud Design/methodology/approach – The research was conducted within a constructivist paradigm. A total of 28 semi-structured interviews (face-to-face or telephone) with 31 visually impaired people were conducted. Framework analysis was used to analyse the results.\\...

  15. Microorganisms maintain crowding homeostasis

    NARCIS (Netherlands)

    van den Berg, Jonas; Boersma, Arnold J; Poolman, Bert

    2017-01-01

    Macromolecular crowding affects the mobility of biomolecules, protein folding and stability, and the association of macromolecules with each other. Local differences in crowding that arise as a result of subcellular components and supramolecular assemblies contribute to the structural organization

  16. Un-explained visual loss following silicone oil removal: results of the Pan American Collaborative Retina Study (PACORES) Group.

    Science.gov (United States)

    Roca, Jose A; Wu, Lihteh; Berrocal, Maria; Rodriguez, Francisco; Alezzandrini, Arturo; Alvira, Gustavo; Velez-Montoya, Raul; Quiroz-Mercado, Hugo; Fernando Arevalo, J; Serrano, Martín; Lima, Luiz H; Figueroa, Marta; Farah, Michel; Chico, Giovanna

    2017-01-01

    To report the incidence and clinical features of patients that experienced un-explained visual loss following silicone oil (SO) removal. Multicenter retrospective study of patients that underwent SO removal during 2000-2012. Visual loss of ≥2 lines was considered significant. A total of 324 eyes of 324 patients underwent SO removal during the study period. Forty two (13%) eyes suffered a significant visual loss following SO removal. Twenty three (7.1%) of these eyes lost vision secondary to known causes. In the remaining 19 (5.9%) eyes, the loss of vision was not explained by any other pathology. Eleven of these 19 patients (57.9%) were male. The mean age of this group was 49.2 ± 16.4 years. Eyes that had an un-explained visual loss had a mean IOP while the eye was filled with SO of 19.6 ± 6.9 mm Hg. The length of time that the eye was filled with SO was 14.8 ± 4.4 months. In comparison, eyes that did not experience visual loss had a mean IOP of 14 ± 7.3 mm Hg (p < 0.0002) and a mean tamponade duration of 9.3 ± 10.9 months (p < 0.0001). An un-explained visual loss after SO removal was observed in 5.9% of eyes. Factors associated with this phenomenon included a higher IOP and longer SO tamponade duration.

  17. Music-reading training alleviates crowding with musical notation.

    Science.gov (United States)

    Wong, Yetta Kwailing; Wong, Alan C-N

    2016-06-01

    Crowding refers to the disrupted recognition of an object by nearby distractors. Prior work has shown that real-world music-reading experts experience reduced crowding specifically for musical stimuli. However, it is unclear whether music-reading training reduced the magnitude of crowding or whether individuals showing less crowding are more likely to learn and excel in music reading later. To examine the first possibility, we tested whether crowding can be alleviated by music-reading training in the laboratory. Intermediate-level music readers completed 8 hr of music-reading training within 2 weeks. Their threshold duration for reading musical notes dropped by 44.1% after training to a level comparable with that of extant expert music readers. Importantly, crowding was reduced with musical stimuli but not with the nonmusical stimuli Landolt Cs. In sum, the reduced crowding for musical stimuli in expert music readers can be explained by music-reading training.

  18. Neuronal nonlinearity explains greater visual spatial resolution for darks than lights.

    Science.gov (United States)

    Kremkow, Jens; Jin, Jianzhong; Komban, Stanley J; Wang, Yushi; Lashgari, Reza; Li, Xiaobing; Jansen, Michael; Zaidi, Qasim; Alonso, Jose-Manuel

    2014-02-25

    Astronomers and physicists noticed centuries ago that visual spatial resolution is higher for dark than light stimuli, but the neuronal mechanisms for this perceptual asymmetry remain unknown. Here we demonstrate that the asymmetry is caused by a neuronal nonlinearity in the early visual pathway. We show that neurons driven by darks (OFF neurons) increase their responses roughly linearly with luminance decrements, independent of the background luminance. However, neurons driven by lights (ON neurons) saturate their responses with small increases in luminance and need bright backgrounds to approach the linearity of OFF neurons. We show that, as a consequence of this difference in linearity, receptive fields are larger in ON than OFF thalamic neurons, and cortical neurons are more strongly driven by darks than lights at low spatial frequencies. This ON/OFF asymmetry in linearity could be demonstrated in the visual cortex of cats, monkeys, and humans and in the cat visual thalamus. Furthermore, in the cat visual thalamus, we show that the neuronal nonlinearity is present at the ON receptive field center of ON-center neurons and ON receptive field surround of OFF-center neurons, suggesting an origin at the level of the photoreceptor. These results demonstrate a fundamental difference in visual processing between ON and OFF channels and reveal a competitive advantage for OFF neurons over ON neurons at low spatial frequencies, which could be important during cortical development when retinal images are blurred by immature optics in infant eyes.

  19. Crowding under the Auditory Perspective

    Directory of Open Access Journals (Sweden)

    Fernanda Trindade Deyl

    2017-08-01

    Full Text Available O ambiente de loja apresenta grande importância sobre a experiência de compra pelo consumidor. Nos últimos anos, a quantidade de estudos acerca da atmosfera de loja tem aumentado, com produção de pesquisas sobre os mais diversos elementos presentes no ambiente varejista: iluminação, aromas, atendimento, densidade, entre outros. Estudos já demonstraram que, para fins gerenciais, é importante que os varejistas compreendam como a percepção de crowding afeta a experiência de compra do consumidor, sendo necessário investigar formas de reduzir seus efeitos negativos e acentuar seus efeitos positivos. Para tanto, é importante que os gestores percebam o crowding sob uma abordagem multissensorial preocupando-se com todos os estímulos sensoriais que possam gerar a percepção de densidade elevada e consequente desconforto. Verifica-se, contudo, que a literatura existente sobre o assunto enfatiza, em sua maioria, a perspectiva visual do crowding, não havendo produção sobre o fenômeno abordado sob outros pontos de vista sensoriais. A audição é apresentada como um dos principais sentidos do ser humano, e, a partir disso, este artigo tem por objetivo sugerir uma abordagem mais completa para o estudo de crowding, enfatizando não apenas variáveis visuais que provocam a sensação do fenômeno, mas também as variáveis sonoras presentes em qualquer ambiente de loja e que podem exercer impacto sobre a percepção de crowding.

  20. Crowds and Crisis

    DEFF Research Database (Denmark)

    Borch, Christian

    semantics, and (2) argues that, however timely and consistent with widespread notions of social structures the new semantics appeared, it offered little in terms of actually making sense of crowds, as it in effect removed the focus on crowds as such. As a response to this, the paper argues for reviving...... semantics of crowds associated collective behaviour with irrationality, contagion and hypnotic suggestibility. Precisely this semantic repertoire was called into question after the November revolution: Weimar sociologists, with Theodor Geiger in a lead role, argued for an alternative conception of crowds...

  1. Crowding and Density

    Science.gov (United States)

    Design and Environment, 1972

    1972-01-01

    Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…

  2. Transient brain activity explains the spectral content of steady-state visual evoked potentials.

    Science.gov (United States)

    Gaume, Antoine; Vialatte, François; Dreyfus, Gérard

    2014-01-01

    Steady-state visual evoked potentials (SSVEPs) are widely used in the design of brain-computer interfaces (BCIs). A lot of effort has therefore been devoted to find a fast and reliable way to detect SSVEPs. We study the link between transient and steady-state VEPs and show that it is possible to predict the spectral content of a subject's SSVEPs by simulating trains of transient VEPs. This could lead to a better understanding of evoked potentials as well as to better performances of SSVEP-based BCIs, by providing a tool to improve SSVEP detection algorithms.

  3. Crowds and Speculation

    DEFF Research Database (Denmark)

    Bondo Hansen, Kristian

    , the dissertation offers a broad, yet rigorously focused, historical perspective on crowd phenomena in financial markets. Furthermore, it explores how ideas about crowd action, imitation, herding and contagion were introduced to and became integral parts of the discourses on financial markets. Reiterations......This dissertation undertakes an explorative historical analysis of problems associated with crowd phenomena in the U.S. financial markets between 1890 and 1940. While a study of crowd-related problems in the financial markets invariably involves examinations of panics and crises, the dissertation...... shows that crowds were not exclusively seen as crisis phenomena, but were considered by many financial writers to be of much broader significance to the organisation and functioning of markets. The dissertation claims that it is necessary to explore the close connections between financial markets...

  4. Is the Theory of Mind deficit observed in visual paradigms in schizophrenia explained by an impaired attention toward gaze orientation?

    Science.gov (United States)

    Roux, Paul; Forgeot d'Arc, Baudoin; Passerieux, Christine; Ramus, Franck

    2014-08-01

    Schizophrenia is associated with poor Theory of Mind (ToM), particularly in goal and belief attribution to others. It is also associated with abnormal gaze behaviors toward others: individuals with schizophrenia usually look less to others' face and gaze, which are crucial epistemic cues that contribute to correct mental states inferences. This study tests the hypothesis that impaired ToM in schizophrenia might be related to a deficit in visual attention toward gaze orientation. We adapted a previous non-verbal ToM paradigm consisting of animated cartoons allowing the assessment of goal and belief attribution. In the true and false belief conditions, an object was displaced while an agent was either looking at it or away, respectively. Eye movements were recorded to quantify visual attention to gaze orientation (proportion of time participants spent looking at the head of the agent while the target object changed locations). 29 patients with schizophrenia and 29 matched controls were tested. Compared to controls, patients looked significantly less at the agent's head and had lower performance in belief and goal attribution. Performance in belief and goal attribution significantly increased with the head looking percentage. When the head looking percentage was entered as a covariate, the group effect on belief and goal attribution performance was not significant anymore. Patients' deficit on this visual ToM paradigm is thus entirely explained by a decreased visual attention toward gaze. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Parietal structure and function explain human variation in working memory biases of visual attention.

    Science.gov (United States)

    Soto, David; Rotshtein, Pia; Kanai, Ryota

    2014-04-01

    Recent research indicates that human attention appears inadvertently biased by items that match the contents of working memory (WM). WM-biases can lead to attentional costs when the memory content matches goal-irrelevant items and to attentional benefits when it matches the sought target. Here we used functional and structural MRI data to determine the neural basis of human variation in WM biases. We asked whether human variation in WM-benefits and WM-costs merely reflects the process of attentional capture by the contents of WM or whether variation in WM biases may be associated with distinct forms of cognitive control over internal WM signals based on selection goals. Human ability to use WM contents to facilitate selection was positively correlated with gray matter volume in the left superior posterior parietal cortex (PPC), while the ability to overcome interference by WM-matching distracters was associated with the left inferior PPC in the anterior IPS. Functional activity in the left PPC, measured by functional MRI, also predicted the magnitude of WM-costs on selection. Both structure and function of left PPC mediate the expression of WM biases in human visual attention. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Dense Crowds of Virtual Humans

    NARCIS (Netherlands)

    Stüvel, S.A.

    2016-01-01

    This thesis presents a novel crowd simulation method `Torso Crowds', aimed at the simulation of dense crowds. The method is based on the results of user studies and a motion capture experiment, which are also described in this thesis. Torso Crowds introduces a capsule shape to represent people in

  7. Is word recognition crowded in pure alexia?

    DEFF Research Database (Denmark)

    Sand, Katrine; Habekost, Thomas; Petersen, Anders

    2017-01-01

    Abstract Pure alexia is a selective deficit in reading, which arises following damage to the left ventral occipito-temporal cortex. Crowding, the inability to recognise objects in a clutter, has recently been hypothesised to be the underlying deficit of apperceptive visual agnosia1. Crowding...... normally occurs in peripheral vision, and we therefore tested whether the performance with words at the centre of fixation in a pure alexic patient (LK) is indeed similar to the performance of matched controls in the peripheral visual field. Using an accuracy-based word recognition task with brief, masked...... exposures, we tested word processing in LK and 24 matched controls. LK was tested in central vision, while the controls were tested in central vision and 4.6 degrees to the right of fixation. LK was significantly impaired on visual word recognition in the central visual field but there was no significant...

  8. Airborne Crowd Density Estimation

    Science.gov (United States)

    Meynberg, O.; Kuschk, G.

    2013-10-01

    This paper proposes a new method for estimating human crowd densities from aerial imagery. Applications benefiting from an accurate crowd monitoring system are mainly found in the security sector. Normally crowd density estimation is done through in-situ camera systems mounted on high locations although this is not appropriate in case of very large crowds with thousands of people. Using airborne camera systems in these scenarios is a new research topic. Our method uses a preliminary filtering of the whole image space by suitable and fast interest point detection resulting in a number of image regions, possibly containing human crowds. Validation of these candidates is done by transforming the corresponding image patches into a low-dimensional and discriminative feature space and classifying the results using a support vector machine (SVM). The feature space is spanned by texture features computed by applying a Gabor filter bank with varying scale and orientation to the image patches. For evaluation, we use 5 different image datasets acquired by the 3K+ aerial camera system of the German Aerospace Center during real mass events like concerts or football games. To evaluate the robustness and generality of our method, these datasets are taken from different flight heights between 800 m and 1500 m above ground (keeping a fixed focal length) and varying daylight and shadow conditions. The results of our crowd density estimation are evaluated against a reference data set obtained by manually labeling tens of thousands individual persons in the corresponding datasets and show that our method is able to estimate human crowd densities in challenging realistic scenarios.

  9. Crowding, reading, and developmental dyslexia.

    Science.gov (United States)

    Martelli, Marialuisa; Di Filippo, Gloria; Spinelli, Donatella; Zoccolotti, Pierluigi

    2009-04-17

    We tested the hypothesis that crowding effects are responsible for the reading slowness characteristic of developmental dyslexia. A total of twenty-nine Italian dyslexics and thirty-three age-matched controls participated in various parts of the study. In Experiment 1, we measured contrast thresholds for identifying letters and words as a function of stimulus duration. Thresholds were higher in dyslexics than controls for words (at a limited time exposure) but not for single letters. Adding noise to the stimuli produced comparable effects in dyslexics and controls. At the long time exposure thresholds were comparable in the two groups. In Experiment 2, we measured the spacing between a target letter and two flankers at a fixed level of performance as a function of eccentricity and size. With eccentricity, the critical spacing (CS) scaled in the control group with 0.62 proportionality (a value of b close to Bouma's law, 0.50) and with a greater proportionality (0.95) in the dyslexic group. CS was independent of size in both groups. In Experiment 3, we examined the critical print size (CPS), that is, the increase in reading rate up to a critical character size (S. T. Chung, J. S. Mansfield, & G. E. Legge, 1998). CPS of dyslexic children was greater than that of controls. Individual maximal reading speed was predicted by individual bs (from Experiment 2). The maximal reading rate achieved by dyslexics at CPS (and also for larger print sizes) was below the values observed in controls. We conclude that word analysis in dyslexics is slowed because of greater crowding effects, which limit letter identification in multi-letter arrays across the visual field. We propose that the peripheral reading of normal readers might constitute a model for dyslexic reading. The periphery model accounts for 60% of dyslexics' slowness. After compensating for crowding, the dyslexics' reading rate remains slower than that of proficient readers. This failure is discussed in terms of a

  10. Does a Flatter General Gradient of Visual Attention Explain Peripheral Advantages and Central Deficits in Deaf Adults?

    Science.gov (United States)

    Samar, Vincent J; Berger, Lauren

    2017-01-01

    , in the absence of auditory input, reduced central attentional capacity is not necessarily associated with enhanced peripheral attentional capacity or with flattening of a general attention gradient. Our findings converge with earlier studies suggesting that a general graded trade-off of attentional resources across the visual field does not adequately explain the complex task-dependent spatial distribution of deaf-hearing performance differences reported in the literature. Rather, growing evidence suggests that the spatial distribution of attention-mediated performance in deaf people is determined by sophisticated cross-modal plasticity mechanisms that recruit specific sensory and polymodal cortex to achieve specific compensatory processing goals.

  11. Firms, crowds, and innovation.

    Science.gov (United States)

    Felin, Teppo; Lakhani, Karim R; Tushman, Michael L

    2017-05-01

    The purpose of this article is to suggest a (preliminary) taxonomy and research agenda for the topic of "firms, crowds, and innovation" and to provide an introduction to the associated special issue. We specifically discuss how various crowd-related phenomena and practices-for example, crowdsourcing, crowdfunding, user innovation, and peer production-relate to theories of the firm, with particular attention on "sociality" in firms and markets. We first briefly review extant theories of the firm and then discuss three theoretical aspects of sociality related to crowds in the context of strategy, organizations, and innovation: (1) the functions of sociality (sociality as extension of rationality, sociality as sensing and signaling, sociality as matching and identity), (2) the forms of sociality (independent/aggregate and interacting/emergent forms of sociality), and (3) the failures of sociality (misattribution and misapplication). We conclude with an outline of future research directions and introduce the special issue papers and essays.

  12. Typical magnitude and spatial extent of crowding in autism

    Science.gov (United States)

    Freyberg, Jan; Robertson, Caroline E.; Baron-Cohen, Simon

    2016-01-01

    Enhanced spatial processing of local visual details has been reported in individuals with autism spectrum conditions (ASC), and crowding is postulated to be a mechanism that may produce this ability. However, evidence for atypical crowding in ASC is mixed, with some studies reporting a complete lack of crowding in autism and others reporting a typical magnitude of crowding between individuals with and without ASC. Here, we aim to disambiguate these conflicting results by testing both the magnitude and the spatial extent of crowding in individuals with ASC (N = 25) and age- and IQ-matched controls (N = 23) during an orientation discrimination task. We find a strong crowding effect in individuals with and without ASC, which falls off as the distance between target and flanker is increased. Both the magnitude and the spatial range of this effect were comparable between individuals with and without ASC. We also find typical (uncrowded) orientation discrimination thresholds in individuals with ASC. These findings suggest that the spatial extent of crowding is unremarkable in ASC, and is therefore unlikely to account for the visual symptoms reported in individuals with the diagnosis. PMID:26998801

  13. Steady-state visual evoked potentials can be explained by temporal superposition of transient event-related responses.

    Directory of Open Access Journals (Sweden)

    Almudena Capilla

    Full Text Available BACKGROUND: One common criterion for classifying electrophysiological brain responses is based on the distinction between transient (i.e. event-related potentials, ERPs and steady-state responses (SSRs. The generation of SSRs is usually attributed to the entrainment of a neural rhythm driven by the stimulus train. However, a more parsimonious account suggests that SSRs might result from the linear addition of the transient responses elicited by each stimulus. This study aimed to investigate this possibility. METHODOLOGY/PRINCIPAL FINDINGS: We recorded brain potentials elicited by a checkerboard stimulus reversing at different rates. We modeled SSRs by sequentially shifting and linearly adding rate-specific ERPs. Our results show a strong resemblance between recorded and synthetic SSRs, supporting the superposition hypothesis. Furthermore, we did not find evidence of entrainment of a neural oscillation at the stimulation frequency. CONCLUSIONS/SIGNIFICANCE: This study provides evidence that visual SSRs can be explained as a superposition of transient ERPs. These findings have critical implications in our current understanding of brain oscillations. Contrary to the idea that neural networks can be tuned to a wide range of frequencies, our findings rather suggest that the oscillatory response of a given neural network is constrained within its natural frequency range.

  14. Crowd Motion Analysis Based on Social Force Graph with Streak Flow Attribute

    Directory of Open Access Journals (Sweden)

    Shaonian Huang

    2015-01-01

    Full Text Available Over the past decades, crowd management has attracted a great deal of attention in the area of video surveillance. Among various tasks of video surveillance analysis, crowd motion analysis is the basis of numerous subsequent applications of surveillance video. In this paper, a novel social force graph with streak flow attribute is proposed to capture the global spatiotemporal changes and the local motion of crowd video. Crowd motion analysis is hereby implemented based on the characteristics of social force graph. First, the streak flow of crowd sequence is extracted to represent the global crowd motion; after that, spatiotemporal analogous patches are obtained based on the crowd visual features. A weighted social force graph is then constructed based on multiple social properties of crowd video. The graph is segmented into particle groups to represent the similar motion patterns of crowd video. A codebook is then constructed by clustering all local particle groups, and consequently crowd abnormal behaviors are detected by using the Latent Dirichlet Allocation model. Extensive experiments on challenging datasets show that the proposed method achieves preferable results in the application of crowd motion segmentation and abnormal behavior detection.

  15. Crowding as appropriation

    DEFF Research Database (Denmark)

    Thelle, Mikkel

    2016-01-01

    ofbodies, it is assessed how the agency of the crowd works on animmediate level and in its more lasting effects on urban space.The notion of appropriation is related to the crowd’s claim,formal and informal, as resulting from a negotiation of this,mostly public, space, and articulated in empirical cases...... such aselections, political activism or pickpocketing. Thus, the articlesuggests terms for a bodily focused and historically situatedcrowd theory....

  16. Firms, crowds, and innovation

    Science.gov (United States)

    Felin, Teppo; Lakhani, Karim R; Tushman, Michael L

    2017-01-01

    The purpose of this article is to suggest a (preliminary) taxonomy and research agenda for the topic of “firms, crowds, and innovation” and to provide an introduction to the associated special issue. We specifically discuss how various crowd-related phenomena and practices—for example, crowdsourcing, crowdfunding, user innovation, and peer production—relate to theories of the firm, with particular attention on “sociality” in firms and markets. We first briefly review extant theories of the firm and then discuss three theoretical aspects of sociality related to crowds in the context of strategy, organizations, and innovation: (1) the functions of sociality (sociality as extension of rationality, sociality as sensing and signaling, sociality as matching and identity), (2) the forms of sociality (independent/aggregate and interacting/emergent forms of sociality), and (3) the failures of sociality (misattribution and misapplication). We conclude with an outline of future research directions and introduce the special issue papers and essays. PMID:28690428

  17. Surface Electromigration and Current Crowding

    Science.gov (United States)

    Yongsunthon, R.; Tao, C.; Rous, P.; Williams, E. D.

    enhancement is highly localized near defects and is maximized by sharp variations in geometry that require strong deflections of the current path. Current enhancements up to a factor of 4 are found at the most strongly deflecting defects, while small notches of various shapes typically cause local enhancements of tens of percent to a factor of 2. The perpendicular component of the current flow around defects forms a dipole pattern with length scale determined by the length of the defect along the direction of the current flow. The shape and localization of the dipole pattern vary with the sharpness and symmetry of the defect. The current crowding affect alone is not sufficient to explain the greatly enhanced electromigration force observed for scattering at kink sites at steps.

  18. Setting up crowd science projects

    NARCIS (Netherlands)

    Scheliga, Kaja; Friesike, Sascha; Puschmann, Cornelius; Fecher, Benedikt

    2016-01-01

    Crowd science is scientific research that is conducted with the participation of volunteers who are not professional scientists. Thanks to the Internet and online platforms, project initiators can draw on a potentially large number of volunteers. This crowd can be involved to support data-rich or

  19. Setting up crowd science projects.

    Science.gov (United States)

    Scheliga, Kaja; Friesike, Sascha; Puschmann, Cornelius; Fecher, Benedikt

    2016-11-29

    Crowd science is scientific research that is conducted with the participation of volunteers who are not professional scientists. Thanks to the Internet and online platforms, project initiators can draw on a potentially large number of volunteers. This crowd can be involved to support data-rich or labour-intensive projects that would otherwise be unfeasible. So far, research on crowd science has mainly focused on analysing individual crowd science projects. In our research, we focus on the perspective of project initiators and explore how crowd science projects are set up. Based on multiple case study research, we discuss the objectives of crowd science projects and the strategies of their initiators for accessing volunteers. We also categorise the tasks allocated to volunteers and reflect on the issue of quality assurance as well as feedback mechanisms. With this article, we contribute to a better understanding of how crowd science projects are set up and how volunteers can contribute to science. We suggest that our findings are of practical relevance for initiators of crowd science projects, for science communication as well as for informed science policy making. © The Author(s) 2016.

  20. The wisdom of select crowds.

    Science.gov (United States)

    Mannes, Albert E; Soll, Jack B; Larrick, Richard P

    2014-08-01

    Social psychologists have long recognized the power of statisticized groups. When individual judgments about some fact (e.g., the unemployment rate for next quarter) are averaged together, the average opinion is typically more accurate than most of the individual estimates, a pattern often referred to as the wisdom of crowds. The accuracy of averaging also often exceeds that of the individual perceived as most knowledgeable in the group. However, neither averaging nor relying on a single judge is a robust strategy; each performs well in some settings and poorly in others. As an alternative, we introduce the select-crowd strategy, which ranks judges based on a cue to ability (e.g., the accuracy of several recent judgments) and averages the opinions of the top judges, such as the top 5. Through both simulation and an analysis of 90 archival data sets, we show that select crowds of 5 knowledgeable judges yield very accurate judgments across a wide range of possible settings-the strategy is both accurate and robust. Following this, we examine how people prefer to use information from a crowd. Previous research suggests that people are distrustful of crowds and of mechanical processes such as averaging. We show in 3 experiments that, as expected, people are drawn to experts and dislike crowd averages-but, critically, they view the select-crowd strategy favorably and are willing to use it. The select-crowd strategy is thus accurate, robust, and appealing as a mechanism for helping individuals tap collective wisdom.

  1. GAME THEORETIC ASPECTS OF CROWD RENTING.

    African Journals Online (AJOL)

    Administrator

    Crowd Renting and Virtual Reality: A crowd is a large and definable group of people. A crowd may be definable through a common purpose or set of emotions, such as at a political rally, at a sports event, or simply be made up of many people going about their business in a busy area (e. g. shopping). Crowd psychology is.

  2. Effects of face feature and contour crowding in facial expression adaptation.

    Science.gov (United States)

    Liu, Pan; Montaser-Kouhsari, Leila; Xu, Hong

    2014-12-01

    Prolonged exposure to a visual stimulus, such as a happy face, biases the perception of subsequently presented neutral face toward sad perception, the known face adaptation. Face adaptation is affected by visibility or awareness of the adapting face. However, whether it is affected by discriminability of the adapting face is largely unknown. In the current study, we used crowding to manipulate discriminability of the adapting face and test its effect on face adaptation. Instead of presenting flanking faces near the target face, we shortened the distance between facial features (internal feature crowding), and reduced the size of face contour (external contour crowding), to introduce crowding. We are interested in whether internal feature crowding or external contour crowding is more effective in inducing crowding effect in our first experiment. We found that combining internal feature and external contour crowding, but not either of them alone, induced significant crowding effect. In Experiment 2, we went on further to investigate its effect on adaptation. We found that both internal feature crowding and external contour crowding reduced its facial expression aftereffect (FEA) significantly. However, we did not find a significant correlation between discriminability of the adapting face and its FEA. Interestingly, we found a significant correlation between discriminabilities of the adapting and test faces. Experiment 3 found that the reduced adaptation aftereffect in combined crowding by the external face contour and the internal facial features cannot be decomposed into the effects from the face contour and facial features linearly. It thus suggested a nonlinear integration between facial features and face contour in face adaptation.

  3. Crowding effects in vehicular traffic.

    Directory of Open Access Journals (Sweden)

    Jay Samuel L Combinido

    Full Text Available While the impact of crowding on the diffusive transport of molecules within a cell is widely studied in biology, it has thus far been neglected in traffic systems where bulk behavior is the main concern. Here, we study the effects of crowding due to car density and driving fluctuations on the transport of vehicles. Using a microscopic model for traffic, we found that crowding can push car movement from a superballistic down to a subdiffusive state. The transition is also associated with a change in the shape of the probability distribution of positions from a negatively-skewed normal to an exponential distribution. Moreover, crowding broadens the distribution of cars' trap times and cluster sizes. At steady state, the subdiffusive state persists only when there is a large variability in car speeds. We further relate our work to prior findings from random walk models of transport in cellular systems.

  4. Examining Crowding Using a Real Three-Dimensional Experimental Setup

    Directory of Open Access Journals (Sweden)

    Eberhardt Lisa Valentina

    2017-10-01

    Full Text Available The phenomenon of impaired recognition of peripherally presented visual targets, when flanked by similar stimuli, is referred to as crowding. Studies in a two-dimensional space have shown that lateral distances are critical: the extent of crowding depends on eccentricity of the target stimulus and on the spacing between target and flanking stimuli. The question of whether also distances in depth affect crowding was until now usually investigated using virtual depth. However, virtual and real depth differ, for example with respect to the accommodation-vergence alignment and to effects of blur. Thus, we made an attempt to study crowding in real depth. In our experimental setup, real depth is implemented by two screens, observed via a semi-transparent mirror. Thus, moving the two screens along the line of sight allows simultaneous stimulus presentation with real depth differences. In a first validation study with 18 participants, a fixation cross was fixed in a depth of 190 cm. Single and flanked Landolt rings were presented in 2° of eccentricity in the same depth as fixation, or in front of (170 cm, or behind (215 cm the fixation depth. Results concerning recognition performance show a similar extent of crowding for flanked targets presented in front of, or behind the fixation depth, and flanked targets in the fixation depth. But, concerning reaction time, the difference between isolated and flanked targets was reduced in defocused depths compared to the fixation depth. That is, reaction time toward flanked targets in the fixation depth was higher than in front of, or behind the fixation depth. With the experimental setup, crowding successfully was induced in different real depths. In further studies, the influence of target and flankers in divergent depths on crowding will be investigated.

  5. Leveraging the wisdom of the crowd in software testing

    CERN Document Server

    Sharma, Mukesh

    2015-01-01

    Its scale, flexibility, cost effectiveness, and fast turnaround are just a few reasons why crowdsourced testing has received so much attention lately. While there are a few online resources that explain what crowdsourced testing is all about, there's been a need for a book that covers best practices, case studies, and the future of this technique.Filling this need, Leveraging the Wisdom of the Crowd in Software Testing shows you how to leverage the wisdom of the crowd in your software testing process. Its comprehensive coverage includes the history of crowdsourcing and crowdsourced testing, im

  6. Learning Multimodal Deep Representations for Crowd Anomaly Event Detection

    Directory of Open Access Journals (Sweden)

    Shaonian Huang

    2018-01-01

    Full Text Available Anomaly event detection in crowd scenes is extremely important; however, the majority of existing studies merely use hand-crafted features to detect anomalies. In this study, a novel unsupervised deep learning framework is proposed to detect anomaly events in crowded scenes. Specifically, low-level visual features, energy features, and motion map features are simultaneously extracted based on spatiotemporal energy measurements. Three convolutional restricted Boltzmann machines are trained to model the mid-level feature representation of normal patterns. Then a multimodal fusion scheme is utilized to learn the deep representation of crowd patterns. Based on the learned deep representation, a one-class support vector machine model is used to detect anomaly events. The proposed method is evaluated using two available public datasets and compared with state-of-the-art methods. The experimental results show its competitive performance for anomaly event detection in video surveillance.

  7. Attentional biases using the body in the crowd task: are angry body postures detected more rapidly?

    Science.gov (United States)

    Gilbert, Tracy; Martin, Rachael; Coulson, Mark

    2011-06-01

    Research using schematic faces has consistently demonstrated attentional biases towards threatening information (angry faces), which are accentuated for individuals with higher levels of anxiety. However, research has yet to reveal whether this is the case for other nonverbal channels of communication. In the research reported here, ninety-five undergraduates completed a body in the crowd task analogous to the face in the crowd task, to examine whether attentional biases for threat existed for schematic body postures. Participants demonstrated faster detection of threat. A discrepant angry posture in a neutral crowd was identified quicker than a discrepant happy posture in a neutral crowd. This effect was pronounced for individuals with higher self-reported levels of trait anxiety. Results also demonstrated evidence of delayed disengagement from threat. Individuals were slower (i.e., more distracted) by identical crowds of angry postures rather than happy or neutral crowds and were slower to detect a discrepant neutral posture among an angry crowd than neutral among a happy crowd. These findings are the first to establish threat biases using body postures in a visual search paradigm. The results are in accordance with previous research using schematic face stimuli. Theoretical and practical implications are discussed.

  8. Fixed versus mixed RSA: Explaining visual representations by fixed and mixed feature sets from shallow and deep computational models.

    Science.gov (United States)

    Khaligh-Razavi, Seyed-Mahdi; Henriksson, Linda; Kay, Kendrick; Kriegeskorte, Nikolaus

    2017-02-01

    Studies of the primate visual system have begun to test a wide range of complex computational object-vision models. Realistic models have many parameters, which in practice cannot be fitted using the limited amounts of brain-activity data typically available. Task performance optimization (e.g. using backpropagation to train neural networks) provides major constraints for fitting parameters and discovering nonlinear representational features appropriate for the task (e.g. object classification). Model representations can be compared to brain representations in terms of the representational dissimilarities they predict for an image set. This method, called representational similarity analysis (RSA), enables us to test the representational feature space as is (fixed RSA) or to fit a linear transformation that mixes the nonlinear model features so as to best explain a cortical area's representational space (mixed RSA). Like voxel/population-receptive-field modelling, mixed RSA uses a training set (different stimuli) to fit one weight per model feature and response channel (voxels here), so as to best predict the response profile across images for each response channel. We analysed response patterns elicited by natural images, which were measured with functional magnetic resonance imaging (fMRI). We found that early visual areas were best accounted for by shallow models, such as a Gabor wavelet pyramid (GWP). The GWP model performed similarly with and without mixing, suggesting that the original features already approximated the representational space, obviating the need for mixing. However, a higher ventral-stream visual representation (lateral occipital region) was best explained by the higher layers of a deep convolutional network and mixing of its feature set was essential for this model to explain the representation. We suspect that mixing was essential because the convolutional network had been trained to discriminate a set of 1000 categories, whose frequencies

  9. The mechanism of word crowding.

    Science.gov (United States)

    Yu, Deyue; Akau, Melanie M U; Chung, Susana T L

    2012-01-01

    Word reading speed in peripheral vision is slower when words are in close proximity of other words (Chung, 2004). This word crowding effect could arise as a consequence of interaction of low-level letter features between words, or the interaction between high-level holistic representations of words. We evaluated these two hypotheses by examining how word crowding changes for five configurations of flanking words: the control condition - flanking words were oriented upright; scrambled - letters in each flanking word were scrambled in order; horizontal-flip - each flanking word was the left-right mirror-image of the original; letter-flip - each letter of the flanking word was the left-right mirror-image of the original; and vertical-flip - each flanking word was the up-down mirror-image of the original. The low-level letter feature interaction hypothesis predicts similar word crowding effect for all the different flanker configurations, while the high-level holistic representation hypothesis predicts less word crowding effect for all the alternative flanker conditions, compared with the control condition. We found that oral reading speed for words flanked above and below by other words, measured at 10° eccentricity in the nasal field, showed the same dependence on the vertical separation between the target and its flanking words, for the various flanker configurations. The result was also similar when we rotated the flanking words by 90° to disrupt the periodic vertical pattern, which presumably is the main structure in words. The remarkably similar word crowding effect irrespective of the flanker configurations suggests that word crowding arises as a consequence of interactions of low-level letter features. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Punks, Goths, and Other Eye-Catching Peer Crowds: Do They Fulfill a Function for Shy Youths?

    Science.gov (United States)

    Besic, Nejra; Kerr, Margaret

    2009-01-01

    Adolescent peer crowds such as Punks and Goths are mainly identified by their strikingly unusual or even shocking appearances. Although many studies find these crowds, few have tried to explain why some youths take on these startling or shocking appearances. We hypothesized that an off-putting appearance is a way to cope with behavioral inhibition…

  11. PetroSim - a system to simulate crowd behaviors in emergency situations

    Energy Technology Data Exchange (ETDEWEB)

    Musse, Soraia R.; Silva, Andre T. da; Hardt, Katia; Barros, Leandro M.; Tonietto, Leandro [Universidade do Vale do Rio dos Sinos (UNISINOS), Sao Leopoldo, RS (Brazil). Dept. de Ciencia da Computacao; Roth, Bruno [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Rolim, Tuerte Amaral; Melo, Ricardo U.M.; Felipe, Luiz A.B. [PETROBRAS, Natal/Fortaleza, RN/CE (Brazil). Unidade de Negocios RN/CE

    2004-07-01

    This paper presents a framework to simulate the behaviors of crowds in panic situations. The main motivation for this work is to provide to safety engineers the possibility of simulating several aspects of panic situations involving crowds in real time. To accomplish this, we propose a complete framework to model the semantically informed environment as well as the intelligent virtual agents (IVA), which form the crowd who lives in the simulated virtual city. This work includes the integration of many knowledge areas such as VR, behavioral and visualization aspects required to the development of PetroSim. (author)

  12. Variations in crowding, saccadic precision, and spatial localization reveal the shared topology of spatial vision.

    Science.gov (United States)

    Greenwood, John A; Szinte, Martin; Sayim, Bilge; Cavanagh, Patrick

    2017-04-25

    Visual sensitivity varies across the visual field in several characteristic ways. For example, sensitivity declines sharply in peripheral (vs. foveal) vision and is typically worse in the upper (vs. lower) visual field. These variations can affect processes ranging from acuity and crowding (the deleterious effect of clutter on object recognition) to the precision of saccadic eye movements. Here we examine whether these variations can be attributed to a common source within the visual system. We first compared the size of crowding zones with the precision of saccades using an oriented clock target and two adjacent flanker elements. We report that both saccade precision and crowded-target reports vary idiosyncratically across the visual field with a strong correlation across tasks for all participants. Nevertheless, both group-level and trial-by-trial analyses reveal dissociations that exclude a common representation for the two processes. We therefore compared crowding with two measures of spatial localization: Landolt-C gap resolution and three-dot bisection. Here we observe similar idiosyncratic variations with strong interparticipant correlations across tasks despite considerably finer precision. Hierarchical regression analyses further show that variations in spatial precision account for much of the variation in crowding, including the correlation between crowding and saccades. Altogether, we demonstrate that crowding, spatial localization, and saccadic precision show clear dissociations, indicative of independent spatial representations, whilst nonetheless sharing idiosyncratic variations in spatial topology. We propose that these topological idiosyncrasies are established early in the visual system and inherited throughout later stages to affect a range of higher-level representations.

  13. Eye movements, search and crowding

    NARCIS (Netherlands)

    Vlaskamp, B.N.S.

    2006-01-01

    If you fixate a single letter in a text, you will notice that it is impossible to identify a letter that is only a few letters away. This is caused by letters that flank this target letter. This is an example of the 'crowding' phenomenon, i.e. items that are close enough to each other interfere with

  14. The wireless internet explained

    CERN Document Server

    Rhoton, John

    2001-01-01

    The Wireless Internet Explained covers the full spectrum of wireless technologies from a wide range of vendors, including initiatives by Microsoft and Compaq. The Wireless Internet Explained takes a practical look at wireless technology. Rhoton explains the concepts behind the physics, and provides an overview that clarifies the convoluted set of standards heaped together under the umbrella of wireless. It then expands on these technical foundations to give a panorama of the increasingly crowded landscape of wireless product offerings. When it comes to actual implementation the book gives abundant down-to-earth advice on topics ranging from the selection and deployment of mobile devices to the extremely sensitive subject of security.Written by an expert on Internet messaging, the author of Digital Press''s successful Programmer''s Guide to Internet Mail and X.400 and SMTP: Battle of the E-mail Protocols, The Wireless Internet Explained describes and evaluates the current state of the fast-growing and crucial...

  15. Crowded letter and crowded picture logMAR acuity in children with amblyopia: a quantitative comparison.

    Science.gov (United States)

    O'Boyle, Cathy; Chen, Sean I; Little, Julie-Anne

    2017-04-01

    Clinically, picture acuity tests are thought to overestimate visual acuity (VA) compared with letter tests, but this has not been systematically investigated in children with amblyopia. This study compared VA measurements with the LogMAR Crowded Kay Picture test to the LogMAR Crowded Keeler Letter acuity test in a group of young children with amblyopia. 58 children (34 male) with amblyopia (22 anisometropic, 18 strabismic and 18 with both strabismic/anisometropic amblyopia) aged 4-6 years (mean=68.7, range=48-83 months) underwent VA measurements. VA chart testing order was randomised, but the amblyopic eye was tested before the fellow eye. All participants wore up-to-date refractive correction. The Kay Picture test significantly overestimated VA by 0.098 logMAR (95% limits of agreement (LOA), 0.13) in the amblyopic eye and 0.088 logMAR (95% LOA, 0.13) in the fellow eye, respectively (p0.23). For both the amblyopic and fellow eyes, Bland-Altman plots demonstrated a systematic and predictable difference between Kay Picture and Keeler Letter charts across the range of acuities tested (Keeler acuity: amblyopic eye 0.75 to -0.05 logMAR; fellow eye 0.45 to -0.15 logMAR). Linear regression analysis (pPicture test consistently overestimated VA by approximately 0.10 logMAR when compared with the Keeler Letter test in young children with amblyopia. Due to the predictable difference found between both crowded logMAR acuity tests, it is reasonable to adjust Kay Picture acuity thresholds by +0.10 logMAR to compute expected Keeler Letter acuity scores. 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/.

  16. The effects of crowding on eye movement patterns in reading.

    Science.gov (United States)

    Bricolo, Emanuela; Salvi, Carola; Martelli, Marialuisa; Arduino, Lisa S; Daini, Roberta

    2015-09-01

    Crowding is a phenomenon that characterizes normal periphery limiting letter identification when other letters surround the signal. We investigated the nature of the reading limitation of crowding by analyzing eye-movement patterns. The stimuli consisted of two items varying across trials for letter spacing (spaced, unspaced and increased size), lexicality (words or pseudowords), number of letters (4, 6, 8), and reading modality (oral and silent). In Experiments 1 and 2 (oral and silent reading, respectively) the results show that an increase in letter spacing induced an increase in the number of fixations and in gaze duration, but a reduction in the first fixation duration. More importantly, increasing letter size (Experiment 3) produced the same first fixation duration advantage as empty spacing, indicating that, as predicted by crowding, only center-to-center letter distance, and not spacing per se, matters. Moreover, when the letter size was enlarged the number of fixations did not increase as much as in the previous experiments, suggesting that this measure depends on visual acuity rather than on crowding. Finally, gaze duration, a measure of word recognition, did not change with the letter size enlargement. No qualitative differences were found between oral and silent reading experiments (1 and 2), indicating that the articulatory process did not influence the outcome. Finally, a facilitatory effect of lexicality was found in all conditions, indicating an interaction between perceptual and lexical processing. Overall, our results indicate that crowding influences normal word reading by means of an increase in first fixation duration, a measure of word encoding, which we interpret as a modulatory effect of attention on critical spacing. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Perceptual learning in children with visual impairment improves near visual acuity.

    Science.gov (United States)

    Huurneman, Bianca; Boonstra, F Nienke; Cox, Ralf F A; van Rens, Ger; Cillessen, Antonius H N

    2013-09-17

    This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four- to nine-year-old children with visual impairment. Participants were 45 children with visual impairment and 29 children with normal vision. Children with visual impairment were divided into three groups: a magnifier group (n = 12), a crowded perceptual learning group (n = 18), and an uncrowded perceptual learning group (n = 15). Children with normal vision also were divided in three groups, but were measured only at baseline. Dependent variables were single near visual acuity (NVA), crowded NVA, LH line 50% crowding NVA, number of trials, accuracy, performance time, amount of small errors, and amount of large errors. Children with visual impairment trained during six weeks, two times per week, for 30 minutes (12 training sessions). After training, children showed significant improvement of NVA in addition to specific improvements on the training task. The crowded perceptual learning group showed the largest acuity improvements (1.7 logMAR lines on the crowded chart, P visual impairment benefit from perceptual training. While task-specific improvements were observed in all training groups, transfer to crowded NVA was largest in the crowded perceptual learning group. To our knowledge, this is the first study to provide evidence for the improvement of NVA by perceptual learning in children with visual impairment. (http://www.trialregister.nl number, NTR2537.).

  18. Rhythmic crowd bobbing on a grandstand simulator

    Science.gov (United States)

    Comer, A. J.; Blakeborough, A.; Williams, M. S.

    2013-01-01

    It is widely accepted that concerted human activity such as bouncing or bobbing can excite cantilever grandstands. Crowd coordination can be unwitting and may be exacerbated by structural motion caused by resonant structural response. This is an area of uncertainty in the design and analysis of modern grandstands. This paper presents experimental measurement and analysis of rhythmic crowd bobbing loads obtained from tests on a grandstand simulator with two distinct support conditions; (a) rigid, and; (b) flexible. It was found that significant structural vibration at the bobbing frequency did not increase the effective bobbing load. Structural motion at the bobbing frequency caused a reduction in the dynamic load factor (DLF) at the frequency of the second harmonic while those at the first and third harmonics were unaffected. Two plausible reasons for this are: (a) the bobbing group were unable to supply significant energy to the system at the frequency of the second harmonic; (b) the bobbing group altered their bobbing style to reduce the response of the grandstand simulator. It was deduced that the bobbing group did not absorb energy from the dynamic system. Furthermore, dynamic load factors for groups of test subjects bobbing on a rigid structure were typically greater than those of synthesised groups derived from individuals bobbing alone, possibly due to group effects such as audio and visual stimuli from neighbouring test subjects. Last, the vibration levels experienced by the test subjects appear to be below levels likely to cause discomfort. This is to be expected as the test subjects were themselves controlling the magnitude and duration of vibration for the bobbing tests considered.

  19. Density estimation in aerial images of large crowds for automatic people counting

    Science.gov (United States)

    Herrmann, Christian; Metzler, Juergen

    2013-05-01

    Counting people is a common topic in the area of visual surveillance and crowd analysis. While many image-based solutions are designed to count only a few persons at the same time, like pedestrians entering a shop or watching an advertisement, there is hardly any solution for counting large crowds of several hundred persons or more. We addressed this problem previously by designing a semi-automatic system being able to count crowds consisting of hundreds or thousands of people based on aerial images of demonstrations or similar events. This system requires major user interaction to segment the image. Our principle aim is to reduce this manual interaction. To achieve this, we propose a new and automatic system. Besides counting the people in large crowds, the system yields the positions of people allowing a plausibility check by a human operator. In order to automatize the people counting system, we use crowd density estimation. The determination of crowd density is based on several features like edge intensity or spatial frequency. They indicate the density and discriminate between a crowd and other image regions like buildings, bushes or trees. We compare the performance of our automatic system to the previous semi-automatic system and to manual counting in images. By counting a test set of aerial images showing large crowds containing up to 12,000 people, the performance gain of our new system will be measured. By improving our previous system, we will increase the benefit of an image-based solution for counting people in large crowds.

  20. Wisdom of Crowds in Prisoner's Dilemma Context

    Science.gov (United States)

    Sun, Min; Hadzikadic, Mirsad

    James Surowiecki in his book on the wisdom of crowds [1] writes about the decisions made based on the aggregation of information in groups. He argues that under certain circumstances the wisdom of crowds is often better than that of any single member in the group. These circumstances include diversity of opinion, independence, and decentralization. In this paper, we simulated the Prisoner's Dilemma problem as a complex adaptive system, which allowed us to define a "controllable" crowd. Experiments show that in a crowd where the "membership" can be defined dynamically and where members can communicate with each other and learn from each other, the wisdom-of-crowds approach shows advantage over the best performing members in the crowd.

  1. Verification Games: Crowd-Sourced Formal Verification

    Science.gov (United States)

    2016-03-01

    VERIFICATION GAMES : CROWD-SOURCED FORMAL VERIFICATION UNIVERSITY OF WASHINGTON MARCH 2016 FINAL TECHNICAL REPORT...DATES COVERED (From - To) JUN 2012 – SEP 2015 4. TITLE AND SUBTITLE VERIFICATION GAMES : CROWD-SOURCED FORMAL VERIFICATION 5a. CONTRACT NUMBER FA8750...clarification memorandum dated 16 Jan 09. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Over the more than three years of the project Verification Games : Crowd-sourced

  2. [On hospital emergency department crowding].

    Science.gov (United States)

    Tudela, Pere; Mòdol, Josep Maria

    2015-01-01

    Recent years have seen a range of measures deployed to curb crowding in hospital emergency departments, but as episodes of overcrowding continue to occur the discussion of causes and possible solutions remains open. The problem is universal, and efforts to revamp health care systems as a result of current socioeconomic circumstances have put emergency services in the spotlight. Consensus was recently achieved on criteria that define emergency department overcrowding. The causes are diverse and include both external factors and internal ones, in the form of attributes specific to a department. The factors that have the most impact, however, involve hospital organization, mainly the availability of beds and the difficulty of assigning them to emergency patients requiring admission. Crowding is associated with decreases in most health care quality indicators, as departments see increases in the number of patients waiting, the time until initial processing, and the time until a physician or nurse intervenes. Crowding is also associated with risk for more unsatisfactory clinical outcomes. This situation leads to dissatisfaction all around-of patients, families, and staff-as aspects such as dignity, comfort, and privacy deteriorate. Proposals to remedy the problem include assuring that the staff and structural resources of a facility meet minimum standards and are all working properly, facilitating access to complementary tests, and providing observation areas and short-stay units. The response of hospitals to the situation in emergency departments should include alternatives to conventional admission, through means for rapid diagnosis, day hospitals, and home hospitalization as well as by offering a clear response in cases where admission is needed, granting easier access to beds that are in fact available. For its part, the health system overall, should improve the care of patients with chronic diseases, so that fewer admissions are required. It is also essential to

  3. Emergency department crowding in Singapore: Insights from a systems thinking approach.

    Science.gov (United States)

    Schoenenberger, Lukas K; Bayer, Steffen; Ansah, John P; Matchar, David B; Mohanavalli, Rajagopal L; Lam, Sean Sw; Ong, Marcus Eh

    2016-01-01

    Emergency Department crowding is a serious and international health care problem that seems to be resistant to most well intended but often reductionist policy approaches. In this study, we examine Emergency Department crowding in Singapore from a systems thinking perspective using causal loop diagramming to visualize the systemic structure underlying this complex phenomenon. Furthermore, we evaluate the relative impact of three different policies in reducing Emergency Department crowding in Singapore: introduction of geriatric emergency medicine, expansion of emergency medicine training, and implementation of enhanced primary care. The construction of the qualitative causal loop diagram is based on consultations with Emergency Department experts, direct observation, and a thorough literature review. For the purpose of policy analysis, a novel approach, the path analysis, is applied. The path analysis revealed that both the introduction of geriatric emergency medicine and the expansion of emergency medicine training may be associated with undesirable consequences contributing to Emergency Department crowding. In contrast, enhancing primary care was found to be germane in reducing Emergency Department crowding; in addition, it has apparently no negative side effects, considering the boundary of the model created. Causal loop diagramming was a powerful tool for eliciting the systemic structure of Emergency Department crowding in Singapore. Additionally, the developed model was valuable in testing different policy options.

  4. O fenómeno de Crowding e as suas implicações na ambliopia

    OpenAIRE

    Yanchik, Nataliya

    2012-01-01

    Fenómeno de Crowding refere-se ao facto da acuidade visual para Optótipos cercados por barras ou outros optótipos, ser pior do que a acuidade visual para os optótipos isolados. Sabe-se que o fenómeno de crowding é mais pronunciado em pessoas com baixa visão, por exemplo amblíopes, do que em pessoas com a visão normal. O objetivo do presente trabalho é perceber os mecanismos subjacentes ao fenómeno de crowding, tanto físicos como óticos ou neurológicos, bem como a sua influência na visão do...

  5. How crowded is the prokaryotic cytoplasm?

    NARCIS (Netherlands)

    Spitzer, Jan; Poolman, Bert; Ferguson, Stuart

    2013-01-01

    We consider biomacromolecular crowding within the cytoplasm of prokaryotic cells as a two-phase system of 'supercrowded' cytogel and 'dilute' cytosol; we simplify and quantify this model for a coccoid cell over a wide range of biomacromolecular crowding. The key result shows that the supercrowded

  6. Socialization of Social Anxiety in Adolescent Crowds

    Science.gov (United States)

    Van Zalk, Nejra; Van Zalk, Maarten Herman Walter; Kerr, Margaret

    2011-01-01

    In this study, we looked at whether social anxiety is socialized, or influenced by peers' social anxiety, more in some peer crowds than others. Adolescents in crowds with eye-catching appearances such as Goths and Punks (here termed "Radical"), were compared with three comparison groups. Using data from 796 adolescents (353 girls and 443 boys; M…

  7. Pervasive Adaptation in Car Crowds

    Science.gov (United States)

    Ferscha, Alois; Riener, Andreas

    Advances in the miniaturization and embedding of electronics for microcomputing, communication and sensor/actuator systems, have fertilized the pervasion of technology into literally everything. Pervasive computing technology is particularly flourishing in the automotive domain, exceling the “smart car”, embodying intelligent control mechanics, intelligent driver assistance, safety and comfort systems, navigation, tolling, fleet management and car-to-car interaction systems, as one of the outstanding success stories of pervasive computing. This paper raises the issue of the socio-technical phenomena emerging from the reciprocal interrelationship between drivers and smart cars, particularly in car crowds. A driver-vehicle co-model (DVC-model) is proposed, expressing the complex interactions between the human driver and the in-car and on-car technologies. Both explicit (steering, shifting, overtaking), as well as implicit (body posture, respiration) interactions are considered, and related to the drivers vital state (attentive, fatigue, distracted, aggressive). DVC-models are considered as building blocks in large scale simulation experiments, aiming to analyze and understand adaptation phenomena rooted in the feed-back loops among individual driver behavior and car crowds.

  8. POI Summarization by Aesthetics Evaluation From Crowd Source Social Media.

    Science.gov (United States)

    Qian, Xueming; Li, Cheng; Lan, Ke; Hou, Xingsong; Li, Zhetao; Han, Junwei

    2018-03-01

    Place-of-Interest (POI) summarization by aesthetics evaluation can recommend a set of POI images to the user and it is significant in image retrieval. In this paper, we propose a system that summarizes a collection of POI images regarding both aesthetics and diversity of the distribution of cameras. First, we generate visual albums by a coarse-to-fine POI clustering approach and then generate 3D models for each album by the collected images from social media. Second, based on the 3D to 2D projection relationship, we select candidate photos in terms of the proposed crowd source saliency model. Third, in order to improve the performance of aesthetic measurement model, we propose a crowd-sourced saliency detection approach by exploring the distribution of salient regions in the 3D model. Then, we measure the composition aesthetics of each image and we explore crowd source salient feature to yield saliency map, based on which, we propose an adaptive image adoption approach. Finally, we combine the diversity and the aesthetics to recommend aesthetic pictures. Experimental results show that the proposed POI summarization approach can return images with diverse camera distributions and aesthetics.

  9. Demotivating incentives and motivation crowding out in charitable giving.

    Science.gov (United States)

    Chao, Matthew

    2017-07-11

    Research has shown that extrinsic incentives can crowd out intrinsic motivation in many contexts. Despite this, many nonprofits offer conditional thank-you gifts, such as mugs or tote bags, in exchange for donations. In collaboration with a nonprofit, this study implements a direct mail field experiment and demonstrates that thank-you gifts reduced donation rates in a fundraising campaign. Attention-based multiattribute choice models suggest that this is because prospective donors shift attention to the salient gift offer, causing them to underweight less salient intrinsic motives. Attention to the gift may also cause individuals to adopt a more cost-benefit mindset, further de-emphasizing intrinsic motives. Consistent with these hypotheses, crowding out was driven by those who donated higher amounts in the previous year (i.e., those who likely had higher intrinsic motivation). In a complementary online experiment, thank-you gifts also reduced donation rates but only when the gift was visually salient. This corroborates the mediating role of attention in crowding out. Taken together, the laboratory and field results demonstrate that this fundraising technique can be demotivating in some contexts and that this may occur through an attention-based mechanism.

  10. Complexity explained

    CERN Document Server

    Erdi, Peter

    2008-01-01

    This book explains why complex systems research is important in understanding the structure, function and dynamics of complex natural and social phenomena. Readers will learn the basic concepts and methods of complex system research.

  11. Structures and functions in the crowded nucleus: new biophysical insights

    Directory of Open Access Journals (Sweden)

    Ronald eHancock

    2014-09-01

    Full Text Available Concepts and methods from the physical sciences have catalysed remarkable progress in understanding the cell nucleus in recent years. To share this excitement with physicists and encourage their interest in this field, this review offers an overview of how the physics which underlies structures and functions in the nucleus is becoming more clear thanks to methods which have been developed to simulate and study macromolecules, polymers, and colloids. The environment in the nucleus is very crowded with macromolecules, making entropic (depletion forces major determinants of interactions. Simulation and experiments are consistent with their key role in forming membraneless compartments such as nucleoli, PML and Cajal bodies, and discrete territories for chromosomes. The chromosomes, giant linear polyelectrolyte polymers, exist in vivo in a state like a polymer melt. Looped conformations are predicted in crowded conditions, and have been confirmed experimentally and are central to the regulation of gene expression. Polymer theory has revealed how the chromosomes are so highly compacted in the nucleus, forming a crumpled globule with fractal properties which avoids knots and entanglements in DNA while allowing facile accessibility for its replication and transcription. Entropic repulsion between looped polymers can explain the confinement of each chromosome to a discrete region of the nucleus. Crowding and looping are predicted to facilitate finding the specific targets of factors which modulate activities of DNA. Simulation shows that entropic effects contribute to finding and repairing potentially lethal double-strand breaks in DNA by increasing the mobility of the broken ends, favouring their juxtaposition for repair. Signaling pathways are strongly influenced by crowding, which favours a processive mode of response (consecutive reactions without releasing substrates. This new information contributes to understanding the sometimes counter

  12. Attentional Allocation of Autism Spectrum Disorder Individuals: Searching for a Face-in-the-Crowd

    Science.gov (United States)

    Moore, David J.; Reidy, John; Heavey, Lisa

    2016-01-01

    A study is reported which tests the proposition that faces capture the attention of those with autism spectrum disorders less than a typical population. A visual search task based on the Face-in-the-Crowd paradigm was used to examine the attentional allocation of autism spectrum disorder adults for faces. Participants were required to search for…

  13. Finding a Face in the Crowd: Testing the Anger Superiority Effect in Asperger Syndrome

    Science.gov (United States)

    Ashwin, Chris; Wheelwright, Sally; Baron-Cohen, Simon

    2006-01-01

    Social threat captures attention and is processed rapidly and efficiently, with many lines of research showing involvement of the amygdala. Visual search paradigms looking at social threat have shown angry faces "pop-out" in a crowd, compared to happy faces. Autism and Asperger Syndrome (AS) are neurodevelopmental conditions…

  14. Applying crowd psychology to develop recommendations for the management of mass decontamination.

    Science.gov (United States)

    Carter, Holly; Drury, John; Rubin, G James; Williams, Richard; Amlôt, Richard

    2015-01-01

    Mass decontamination is a public health intervention employed by emergency responders following a chemical, biological, or radiological release. It involves a crowd of people whose interactions with each other and with the emergency responders managing the incident are likely to affect the success of the decontamination process. The way in which members of the public collectively experience decontamination is likely to affect their behavior and hence is crucial to the success of the decontamination process. Consequently, responders and the responsible authorities need to understand crowd psychology during mass emergencies and disasters. Recently, the social identity approach to crowd psychology has been applied to explain public perceptions and behavior during mass emergencies. This approach emphasizes that crowd events are characteristically intergroup encounters, in which the behavior of one group can affect the perceptions and behavior of another. We summarize the results from a program of research in which the social identity approach was applied to develop and test recommendations for the management of mass decontamination. The findings from this program of research show that (1) responders' perceptions of crowd behavior matter; (2) participants value greater communication and this affects their compliance; and (3) social identity processes explain the relationship between effective responder communication and relevant outcome variables, such as public compliance, public cooperation, and public anxiety. Based on this program of research, we recommend 4 responder management strategies that focus on increasing public compliance, increasing orderly and cooperative behavior among members of the public, reducing public anxiety, and respecting public needs for privacy.

  15. Applying Crowd Psychology to Develop Recommendations for the Management of Mass Decontamination

    Science.gov (United States)

    Drury, John; Rubin, G. James; Williams, Richard; Amlôt, Richard

    2015-01-01

    Mass decontamination is a public health intervention employed by emergency responders following a chemical, biological, or radiological release. It involves a crowd of people whose interactions with each other and with the emergency responders managing the incident are likely to affect the success of the decontamination process. The way in which members of the public collectively experience decontamination is likely to affect their behavior and hence is crucial to the success of the decontamination process. Consequently, responders and the responsible authorities need to understand crowd psychology during mass emergencies and disasters. Recently, the social identity approach to crowd psychology has been applied to explain public perceptions and behavior during mass emergencies. This approach emphasizes that crowd events are characteristically intergroup encounters, in which the behavior of one group can affect the perceptions and behavior of another. We summarize the results from a program of research in which the social identity approach was applied to develop and test recommendations for the management of mass decontamination. The findings from this program of research show that (1) responders' perceptions of crowd behavior matter; (2) participants value greater communication and this affects their compliance; and (3) social identity processes explain the relationship between effective responder communication and relevant outcome variables, such as public compliance, public cooperation, and public anxiety. Based on this program of research, we recommend 4 responder management strategies that focus on increasing public compliance, increasing orderly and cooperative behavior among members of the public, reducing public anxiety, and respecting public needs for privacy. PMID:25812428

  16. The impact of crowd noise on officiating in Muay Thai: achieving external validity in an experimental setting

    Directory of Open Access Journals (Sweden)

    Tony D Myers

    2012-09-01

    Full Text Available Numerous factors have been proposed to explain the home advantage in sport. Several authors have suggested that a partisan home crowd enhances home advantage and that this is at least in part a consequence of their influence on officiating. However, while experimental studies examining this phenomenon have high levels of internal validity (since only the ‘crowd noise’ intervention is allowed to vary, they suffer from a lack of external validity, with decision-making in a laboratory setting typically bearing little resemblance to decision-making in live sports settings. Conversely, observational and quasi-experimental studies with high levels of external validity suffer from low levels of internal validity as countless factors besides crowd noise vary. The present study provides a unique opportunity to address these criticisms, by conducting a controlled experiment on the impact of crowd noise on officiating in a live tournament setting. Seventeen qualified judges officiated on thirty Thai boxing bouts in a live international tournament setting featuring ‘home’ and ‘away’ boxers. In each bout, judges were randomised into a ‘noise’ (live sound or ‘no crowd noise’ (noise cancelling headphones and white noise condition, resulting in 59 judgements in the ‘no crowd noise’ and 61 in the ‘crowd noise’ condition. The results provide the first experimental evidence of the impact of live crowd noise on officials in sport. A cross-classified statistical model indicated that crowd noise had a statistically significant impact, equating to just over half a point per bout (in the context of five round bouts with the ‘ten point must’ scoring system shared with professional boxing. The practical significance of the findings, their implications for officiating and for the future conduct of crowd noise studies are discussed.

  17. The impact of crowd noise on officiating in muay thai: achieving external validity in an experimental setting.

    Science.gov (United States)

    Myers, Tony; Balmer, Nigel

    2012-01-01

    Numerous factors have been proposed to explain the home advantage in sport. Several authors have suggested that a partisan home crowd enhances home advantage and that this is at least in part a consequence of their influence on officiating. However, while experimental studies examining this phenomenon have high levels of internal validity (since only the "crowd noise" intervention is allowed to vary), they suffer from a lack of external validity, with decision-making in a laboratory setting typically bearing little resemblance to decision-making in live sports settings. Conversely, observational and quasi-experimental studies with high levels of external validity suffer from low levels of internal validity as countless factors besides crowd noise vary. The present study provides a unique opportunity to address these criticisms, by conducting a controlled experiment on the impact of crowd noise on officiating in a live tournament setting. Seventeen qualified judges officiated on thirty Thai boxing bouts in a live international tournament setting featuring "home" and "away" boxers. In each bout, judges were randomized into a "noise" (live sound) or "no crowd noise" (noise-canceling headphones and white noise) condition, resulting in 59 judgments in the "no crowd noise" and 61 in the "crowd noise" condition. The results provide the first experimental evidence of the impact of live crowd noise on officials in sport. A cross-classified statistical model indicated that crowd noise had a statistically significant impact, equating to just over half a point per bout (in the context of five round bouts with the "10-point must" scoring system shared with professional boxing). The practical significance of the findings, their implications for officiating and for the future conduct of crowd noise studies are discussed.

  18. When Bureaucracy Meets the Crowd

    DEFF Research Database (Denmark)

    Kornberger, Martin; Meyer, Renate; Brandtner, Christof

    2017-01-01

    and Open Government; and second, to critically theorize the ongoing rationalization of public administration in spite of constant challenges to its bureaucratic principles. In so doing, the paper advances our understanding of modern bureaucratic organizations under the condition of increased openness...... how the encounter between the city administration and “the open” juxtaposes the decentralizing principles of the crowd, such as transparency, participation, and distributed cognition, with the centralizing principles of bureaucracy, such as secrecy, expert knowledge, written files, and rules....... The paper explores how this theoretical conundrum is played out and how senior city managers perceive Open Government in relation to the bureaucratic nature of their administration. The purpose of this paper is twofold: first, to empirically trace the complexities of the encounter between bureaucracy...

  19. Agnosic vision is like peripheral vision, which is limited by crowding.

    Science.gov (United States)

    Strappini, Francesca; Pelli, Denis G; Di Pace, Enrico; Martelli, Marialuisa

    2017-04-01

    Visual agnosia is a neuropsychological impairment of visual object recognition despite near-normal acuity and visual fields. A century of research has provided only a rudimentary account of the functional damage underlying this deficit. We find that the object-recognition ability of agnosic patients viewing an object directly is like that of normally-sighted observers viewing it indirectly, with peripheral vision. Thus, agnosic vision is like peripheral vision. We obtained 14 visual-object-recognition tests that are commonly used for diagnosis of visual agnosia. Our "standard" normal observer took these tests at various eccentricities in his periphery. Analyzing the published data of 32 apperceptive agnosia patients and a group of 14 posterior cortical atrophy (PCA) patients on these tests, we find that each patient's pattern of object recognition deficits is well characterized by one number, the equivalent eccentricity at which our standard observer's peripheral vision is like the central vision of the agnosic patient. In other words, each agnosic patient's equivalent eccentricity is conserved across tests. Across patients, equivalent eccentricity ranges from 4 to 40 deg, which rates severity of the visual deficit. In normal peripheral vision, the required size to perceive a simple image (e.g., an isolated letter) is limited by acuity, and that for a complex image (e.g., a face or a word) is limited by crowding. In crowding, adjacent simple objects appear unrecognizably jumbled unless their spacing exceeds the crowding distance, which grows linearly with eccentricity. Besides conservation of equivalent eccentricity across object-recognition tests, we also find conservation, from eccentricity to agnosia, of the relative susceptibility of recognition of ten visual tests. These findings show that agnosic vision is like eccentric vision. Whence crowding? Peripheral vision, strabismic amblyopia, and possibly apperceptive agnosia are all limited by crowding, making it

  20. Effect of macromolecular crowding on the rate of diffusion-limited ...

    Indian Academy of Sciences (India)

    on percolation and diffusion in disordered systems to study the effect of macromolecular crowding on the enzymatic reaction rates. The model qualitatively explains some of the experimental observations. Keywords. Enzyme kinetics; Monte Carlo; percolation; random walk; obstacle. PACS Nos 02.50.Ey; 05.40.Jc; 05.60.Cd.

  1. Effect of macromolecular crowding on the rate of diffusion-limited ...

    Indian Academy of Sciences (India)

    The enzymatic reaction rate has been shown to be affected by the presence of such macromolecules. A simple numerical model is proposed here based on percolation and diffusion in disordered systems to study the effect of macromolecular crowding on the enzymatic reaction rates. The model qualitatively explains some ...

  2. A phytochemical-rich diet may explain the absence of age-related decline in visual acuity of Amazonian hunter-gatherers in Ecuador.

    Science.gov (United States)

    London, Douglas S; Beezhold, Bonnie

    2015-02-01

    Myopia is absent in undisturbed hunter-gatherers but ubiquitous in modern populations. The link between dietary phytochemicals and eye health is well established, although transition away from a wild diet has reduced phytochemical variety. We hypothesized that when larger quantities and greater variety of wild, seasonal phytochemicals are consumed in a food system, there will be a reduced prevalence of degenerative-based eye disease as measured by visual acuity. We compared food systems and visual acuity across isolated Amazonian Kawymeno Waorani hunter-gatherers and neighboring Kichwa subsistence agrarians, using dietary surveys, dietary pattern observation, and Snellen Illiterate E visual acuity examinations. Hunter-gatherers consumed more food species (130 vs. 63) and more wild plants (80 vs. 4) including 76 wild fruits, thereby obtaining larger variety and quantity of phytochemicals than agrarians. Visual acuity was inversely related to age only in agrarians (r = -.846, P .05). This unusual absence of juvenile-onset vision problems may be related to local, organic, whole food diets of subsistence food systems isolated from modern food production. Our results suggest that intake of a wider variety of plant foods supplying necessary phytochemicals for eye health may help maintain visual acuity and prevent degenerative eye conditions as humans age. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Understanding Modes of Crowdsourcing and Related Crowd Motivators

    OpenAIRE

    Ståhlbröst, Anna; Constantinos Marios Angelopoulos; Orestis Evangelatos; Srdjan Krco; Sotiris Nikoletseas; Theofanis Raptis; Sebastien Ziegler

    2015-01-01

    Today there is a very strong and rapidly growing interest and actions focusing on involving the crowd in different initiatives. This trend can be labelled crowdsourcing where companies want to tap into the wisdom of the crowd, or to engage crowds to carry our micro-tasks to achieve a higher goal. Hence, crowds can be engaged in many different types of activities spanning from idea generation to crisis management. These crowds are also motivated to participate and contribute differently, for s...

  4. Towards a South African crowd control model

    CSIR Research Space (South Africa)

    Modise, M

    2013-03-01

    Full Text Available by violence stemming largely from clashes between the protesters and the law enforcement agencies, which results in property vandalism and even death. For this reason, there is a demand for greater understanding, modelling and simulating crowd control...

  5. NIH Abroad: Pictures Are Crowd Pullers

    Science.gov (United States)

    ... Home Current Issue Past Issues Special Section NIH Abroad: Pictures Are Crowd Pullers Past Issues / Spring 2008 ... Faculty of Medicine, University of Makerere, in Kampala, working with Julia Royall, chief of international programs at ...

  6. PROCEED and Crowd-sourced Formal Verification

    Science.gov (United States)

    2011-11-07

    VA November 7, 2011 PROCEED and Crowd-sourced Formal Verification Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting...TITLE AND SUBTITLE PROCEED and Crowd-sourced Formal Verification 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d... Formal Verification (CSFV) Approved for Public Release, Distribution Unlimited. The Problem Application specific functions Are there fundamental

  7. Crowd Behavior Algorithm Development for COMBAT XXI

    Science.gov (United States)

    2017-05-30

    interest, such as museums . The literature addresses many aspects of crowd dynamics. For instance, Berk (1974) illustrates a crowd that forms in protest of...uses underlying driving parameters from the OCEAN personality model, 5 which is general made up of five factors defined as openness to experience...to develop a better collateral damage estimator model within the Air Force agent-based systems effectiveness analysis simulation, SEAS, combat model

  8. Automatic Crowd Analysis from Airborne Images

    OpenAIRE

    Sirmacek, Beril; Reinartz, Peter

    2011-01-01

    Recently automatic detection of people and crowded areas from images became a very important research field, since it can provide crucial information especially for police departments and crisis management teams. Detection of crowd and measuring the density of people can prevent possible accidents or unpleasant conditions to appear. Understanding behavioral dynamics of large people groups can also help to estimate future states of underground passages, shopping center like public entrances...

  9. Harnessing the wisdom of the inner crowd.

    Science.gov (United States)

    Herzog, Stefan M; Hertwig, Ralph

    2014-10-01

    Ever since Galton's classic demonstration of the wisdom of crowds in estimating the weight of a slaughtered ox, scholars of the mind and the public alike have been fascinated by the counterintuitive accuracy achieved by simply averaging a number of people's estimates. Surprisingly, individuals can, to some extent, harness the wisdom of crowds within the confines of their own mind by averaging self-generated, nonredundant estimates. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. SPSS explained

    CERN Document Server

    Hinton, Perry R; Brownlow, Charlotte

    2014-01-01

    SPSS Explained provides the student with all that they need to undertake statistical analysis using SPSS. It combines a step-by-step approach to each procedure with easy to follow screenshots at each stage of the process. A number of other helpful features are provided: regular advice boxes with tips specific to each test explanations divided into 'essential' and 'advanced' sections to suit readers at different levels frequently asked questions at the end of each chapter. The first edition of this popular book has been fully updated for IBM SPSS version 21 and also includes: chapters that expl

  11. Housing crowding effects on children's wellbeing.

    Science.gov (United States)

    Solari, Claudia D; Mare, Robert D

    2012-03-01

    The degree to which children grow up in crowded housing is a neglected but potentially important aspect of social inequality. Poor living conditions can serve as a mechanism of social stratification, affecting children's wellbeing and resulting in the intergenerational transmission of social inequality. This paper reports an investigation of housing crowding on children's academic achievement, behavior, and health in the US and Los Angeles, a city with atypically high levels of crowding. We use data from the Panel Study of Income Dynamics' Child Development Supplement and the Los Angeles Family and Neighborhood Survey to explore the effect of living in a crowded home on an array of child wellbeing indicators. We find that several dimensions of children's wellbeing suffer when exposed to crowded living conditions, particularly in Los Angeles, even after controlling for socioeconomic status. The negative effects on children raised in crowded homes can persist throughout life, affecting their future socioeconomic status and adult wellbeing. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Semi-automatic people counting in aerial images of large crowds

    Science.gov (United States)

    Herrmann, Christian; Metzler, Juergen; Willersinn, Dieter

    2012-09-01

    Counting people in crowds is a common problem in visual surveillance. Many solutions are just designed to count less than one hundred people. Only few systems have been tested on large crowds of several hundred people and no known counting system has been tested on crowds of several thousand people. Furthermore, none of these large scale systems delivers people's positions, they just estimate the number. But having the position of people would be a large benefit, since this would enable a human observer to carry out a plausibility check. In addition, most approaches require video data as input or a scene model. In order to generally solve the problem, these assumptions must not be made. We propose a system that can count people on single aerial images including mosaic images generated from video data. No assumptions about crowd density will be made, i. e. the system has to work from low to very high density. The main challenge is the large variety of possible input data. Typical scenarios would be public events such as demonstrations or open air concerts. Our system uses a model-based detection of individual humans. This includes the determination of their positions and the total number. In order to cope with the given challenges we divide our system into three steps: foreground segmentation, person size determination and person detection. We evaluate our proposed system on a variety of aerial images showing large crowds with up to several thousand people

  13. Cartographic visualization

    NARCIS (Netherlands)

    Kraak, M.J.; Wright, James D.

    2015-01-01

    The cartographic visualization process, based on the statement “How do I say what to whom, and is it effective?” is explained for both presenting and exploring spatiotemporal data. The visualization environment and required functionality are described

  14. Revisiting Gustave Le Bon’s crowd theory in light of present-day critique

    DEFF Research Database (Denmark)

    Laursen, Rasmus Beedholm; Møller, Verner

    2017-01-01

    behaviour through the Elaborated Social Identity Model (ESIM). Pioneered by Clifford Stott, the logic of the ESIM has gained ground when interactions between football fans and authorities are to be explained and understood. Therefore, it is tempting to think that the ESIM delivers a solid theoretical......In establishing a valid crowd theory, it seems to have become comme il faut to criticize French mass psychologist Gustave Le Bon’s mass theory. In this respect, football fan studies are no exception. A repeated criticism of Le Bon echoes in publications from scholars who analyse football fan...... understanding of crowd or mass behaviour that proves Le Bon’s crowd theory wrong. However, in this paper, we challenge this perception not only by questioning Drury, Reicher and Stott’s interpretation of Le Bon, but also suggesting that the dialogue strategy that is based upon the ESIM, in fact, validates Le...

  15. Achieving external validity in home advantage research: generalizing crowd noise effects

    Directory of Open Access Journals (Sweden)

    Tony D Myers

    2014-06-01

    Full Text Available Different factors have been postulated to explain the home advantage phenomenon in sport. One plausible explanation investigated has been the influence of a partisan home crowd on sports officials’ decisions. Different types of studies have tested the crowd influence hypothesis including purposefully designed experiments. However, while experimental studies investigating crowd influences have high levels of internal validity, they suffer from a lack of external validity; decision-making in a laboratory setting bearing little resemblance to decision-making in live sports settings. This focused review initially considers threats to external validity in applied and theoretical experimental research. Discussing how such threats can be addressed using representative design by focusing on a recently published study that arguably provides the first experimental evidence of the impact of live crowd noise on officials in sport. The findings of this controlled experiment conducted in a real tournament setting offer some confirmation of the validity of laboratory experimental studies in the area. Finally directions for future research and the future conduct of crowd noise studies are discussed.

  16. Achieving external validity in home advantage research: generalizing crowd noise effects.

    Science.gov (United States)

    Myers, Tony D

    2014-01-01

    Different factors have been postulated to explain the home advantage phenomenon in sport. One plausible explanation investigated has been the influence of a partisan home crowd on sports officials' decisions. Different types of studies have tested the crowd influence hypothesis including purposefully designed experiments. However, while experimental studies investigating crowd influences have high levels of internal validity, they suffer from a lack of external validity; decision-making in a laboratory setting bearing little resemblance to decision-making in live sports settings. This focused review initially considers threats to external validity in applied and theoretical experimental research. Discussing how such threats can be addressed using representative design by focusing on a recently published study that arguably provides the first experimental evidence of the impact of live crowd noise on officials in sport. The findings of this controlled experiment conducted in a real tournament setting offer a level of confirmation of the findings of laboratory studies in the area. Finally directions for future research and the future conduct of crowd noise studies are discussed.

  17. Innovative funding solution for special projects: Crowd funding

    Directory of Open Access Journals (Sweden)

    Sentot Imam Wahjono

    2015-06-01

    Full Text Available The aim of this paper is to examine the influence of crowd funding knowledge, applica-tion, platform, and project initiator toward successful crowd funding. This study conducted by quantitative approach, data have been collected with web-based ques-tionnaires via Kickstarter.com direct message and e-mail to 200 successful crowd funding project initiators as a sample and as much 152 sets questionnaire returned by a complete answer and should be analyzed further. Deployment and data collection take 3 month from October to December 2013. This study found evidence that crowd funding knowledge, crowd funding application, crowd funding platform, and project initiator has positive and significant relationship toward the success of crowd funding. The implication from this research is crowd funding can be a source of capital to finance the projects, not just rely on traditional sources of financing just like banking and capital markets. Crowd funding can be innovative funding solution.

  18. A method of emotion contagion for crowd evacuation

    Science.gov (United States)

    Cao, Mengxiao; Zhang, Guijuan; Wang, Mengsi; Lu, Dianjie; Liu, Hong

    2017-10-01

    The current evacuation model does not consider the impact of emotion and personality on crowd evacuation. Thus, there is large difference between evacuation results and the real-life behavior of the crowd. In order to generate more realistic crowd evacuation results, we present a method of emotion contagion for crowd evacuation. First, we combine OCEAN (Openness, Extroversion, Agreeableness, Neuroticism, Conscientiousness) model and SIS (Susceptible Infected Susceptible) model to construct the P-SIS (Personalized SIS) emotional contagion model. The P-SIS model shows the diversity of individuals in crowd effectively. Second, we couple the P-SIS model with the social force model to simulate emotional contagion on crowd evacuation. Finally, the photo-realistic rendering method is employed to obtain the animation of crowd evacuation. Experimental results show that our method can simulate crowd evacuation realistically and has guiding significance for crowd evacuation in the emergency circumstances.

  19. CrowdAidRepair: A Crowd-Aided Interactive Data Repairing Method

    KAUST Repository

    Zhou, Jian

    2016-03-25

    Data repairing aims at discovering and correcting erroneous data in databases. Traditional methods relying on predefined quality rules to detect the conflict between data may fail to choose the right way to fix the detected conflict. Recent efforts turn to use the power of crowd in data repairing, but the crowd power has its own drawbacks such as high human intervention cost and inevitable low efficiency. In this paper, we propose a crowd-aided interactive data repairing method which takes the advantages of both rule-based method and crowd-based method. Particularly, we investigate the interaction between crowd-based repairing and rule-based repairing, and show that by doing crowd-based repairing to a small portion of values, we can greatly improve the repairing quality of the rule-based repairing method. Although we prove that the optimal interaction scheme using the least number of values for crowd-based repairing to maximize the imputation recall is not feasible to be achieved, still, our proposed solution identifies an efficient scheme through investigating the inconsistencies and the dependencies between values in the repairing process. Our empirical study on three data collections demonstrates the high repairing quality of CrowdAidRepair, as well as the efficiency of the generated interaction scheme over baselines.

  20. The Seasonality of Tuberculosis, Sunlight, Vitamin D, and Household Crowding

    Science.gov (United States)

    Wingfield, Tom; Schumacher, Samuel G.; Sandhu, Gurjinder; Tovar, Marco A.; Zevallos, Karine; Baldwin, Matthew R.; Montoya, Rosario; Ramos, Eric S.; Jongkaewwattana, Chulanee; Lewis, James J.; Gilman, Robert H.; Friedland, Jon S.; Evans, Carlton A.

    2014-01-01

    Background. Unlike other respiratory infections, tuberculosis diagnoses increase in summer. We performed an ecological analysis of this paradoxical seasonality in a Peruvian shantytown over 4 years. Methods. Tuberculosis symptom-onset and diagnosis dates were recorded for 852 patients. Their tuberculosis-exposed cohabitants were tested for tuberculosis infection with the tuberculin skin test (n = 1389) and QuantiFERON assay (n = 576) and vitamin D concentrations (n = 195) quantified from randomly selected cohabitants. Crowding was calculated for all tuberculosis-affected households and daily sunlight records obtained. Results. Fifty-seven percent of vitamin D measurements revealed deficiency (<50 nmol/L). Risk of deficiency was increased 2.0-fold by female sex (P < .001) and 1.4-fold by winter (P < .05). During the weeks following peak crowding and trough sunlight, there was a midwinter peak in vitamin D deficiency (P < .02). Peak vitamin D deficiency was followed 6 weeks later by a late-winter peak in tuberculin skin test positivity and 12 weeks after that by an early-summer peak in QuantiFERON positivity (both P < .04). Twelve weeks after peak QuantiFERON positivity, there was a midsummer peak in tuberculosis symptom onset (P < .05) followed after 3 weeks by a late-summer peak in tuberculosis diagnoses (P < .001). Conclusions. The intervals from midwinter peak crowding and trough sunlight to sequential peaks in vitamin D deficiency, tuberculosis infection, symptom onset, and diagnosis may explain the enigmatic late-summer peak in tuberculosis. PMID:24596279

  1. Perceptual Learning in Children With Visual Impairment Improves Near Visual Acuity

    NARCIS (Netherlands)

    Huurneman, Bianca; Boonstra, F. Nienke; Cox, Ralf F. A.; van Rens, Ger; Cillessen, Antonius H. N.

    PURPOSE. This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four-to nine-year-old children with visual impairment. METHODS. Participants were 45 children with visual impairment and 29 children with normal vision. Children

  2. Perceptual learning in children with visual impairment improves near visual acuity

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.; Cox, R.F.; Rens, G. van; Cillessen, A.H.N.

    2013-01-01

    PURPOSE: This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four- to nine-year-old children with visual impairment. METHODS: Participants were 45 children with visual impairment and 29 children with normal vision. Children

  3. Perceptual Learning in Children With Visual Impairment Improves Near Visual Acuity

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.; Cox, R.F.A.; Rens, G.H.M.B. van; Cillessen, A.H.N.

    2013-01-01

    PURPOSE. This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four-to nine-year-old children with visual impairment. METHODS. Participants were 45 children with visual impairment and 29 children with normal vision. Children

  4. The "motion silencing" illusion results from global motion and crowding.

    Science.gov (United States)

    Turi, Marco; Burr, David

    2013-04-18

    Suchow and Alvarez (2011) recently devised a striking illusion, where objects changing in color, luminance, size, or shape appear to stop changing when they move. They refer to the illusion as "motion silencing of awareness to visual change." Here we present evidence that the illusion results from two perceptual processes: global motion and crowding. We adapted Suchow and Alvarez's stimulus to three concentric rings of dots, a central ring of "target dots" flanked on either side by similarly moving flanker dots. Subjects had to identify in which of two presentations the target dots were continuously changing (sinusoidally) in size, as distinct from the other interval in which size was constant. The results show: (a) Motion silencing depends on target speed, with a threshold around 0.2 rotations per second (corresponding to about 10°/s linear motion). (b) Silencing depends on both target-flanker spacing and eccentricity, with critical spacing about half eccentricity, consistent with Bouma's law. (c) The critical spacing was independent of stimulus size, again consistent with Bouma's law. (d) Critical spacing depended strongly on contrast polarity. All results imply that the "motion silencing" illusion may result from crowding.

  5. EMOTIONAL CONTAGION AND MOOD IN CROWD SERVING AS AUDIENCE

    Directory of Open Access Journals (Sweden)

    Beno Arnejcic

    2015-06-01

    Full Text Available The global world is gradually becoming a world of separated crowds despite the artificial wire and wireless connection through television and the Internet. Crowds remain a prevailing subject of research in different social studies, and the research of changes in the psychological structure of crowds and their characteristics is still of primary interest. The main focus of the research is on the interpretation of the results of the research paper about a special separated crowd called audience. It was observed how students, constituting the crowd, perceive a crowd on video. The observation was focused on the research of emotional contagion and mood in the crowd serving as audience. While watching a mass event on a big screen, the crowd serving as audience emotionally converges with someone else, in our case with public speakers.

  6. Adding more junior residents may worsen emergency department crowding

    National Research Council Canada - National Science Library

    Kawano, Takahisa; Nishiyama, Kei; Hayashi, Hiroyuki

    2014-01-01

    Although increasing staff numbers during shifts when emergency department (ED) crowding is severe can help meet patient demand, it remains unclear how different types of added staff, particularly junior residents, may affect crowding...

  7. Designerly Ways of Exploring Crowds

    NARCIS (Netherlands)

    Li, J.; Vermeeren, A.P.O.S.; De Ridder, H.

    2014-01-01

    In this article, we present examples of using designerly ways to explore “crowd” phenomenon in a cross-disciplinary project named EWiDS. The phrase ‘designerly ways’ refers to visual communication methods such as drawings and videos, which are widely acknowledged as effective approaches to

  8. Crowd-sourcing with Uncertain Quality

    DEFF Research Database (Denmark)

    Papakonstantinou, Athanasios; Bogetoft, Peter

    This article addresses two important issues in crowd-sourcing: ex ante uncertainty about the quality and cost of different workers and strategic behaviour. We present a novel multi-dimensional auction that incentivises the workers to make partial enquiry into the task and to honestly report quality-cost...... estimates based on which the crowd-sourcer can choose the worker that offers the best value for money. The mechanism extends second score auction design to settings where the quality is uncertain and it provides incentives to both collect information and deliver desired qualities....

  9. Virtual Crowds Methods, Simulation, and Control

    CERN Document Server

    Pelechano, Nuria; Allbeck, Jan

    2008-01-01

    There are many applications of computer animation and simulation where it is necessary to model virtual crowds of autonomous agents. Some of these applications include site planning, education, entertainment, training, and human factors analysis for building evacuation. Other applications include simulations of scenarios where masses of people gather, flow, and disperse, such as transportation centers, sporting events, and concerts. Most crowd simulations include only basic locomotive behaviors possibly coupled with a few stochastic actions. Our goal in this survey is to establish a baseline o

  10. Directing the wisdom of the crowd

    DEFF Research Database (Denmark)

    Clauss, Thomas; Breitenecker, Robert J.; Kraus, Sascha

    2017-01-01

    and the community as well as among community members into account. We empirically investigated potential success factors for crowdfunding projects of entrepreneurs on the base of 430 projects from the German crowdfunding platform Visionbakery. Our results show that social interaction during a crowdfunding campaign...... indeed increases the likelihood of its success. As comments from crowd members on particular projects might be positive or negative and can also provide additional argumentation or raise questions, comments can cause a dialog among crowd members. This shows that herding might not only be related...

  11. A field study on real-time self-reported emotions in crowds

    NARCIS (Netherlands)

    Li, J.; Erkin, Z.; De Ridder, H.; Vermeeren, A.P.O.S.

    2013-01-01

    Crowd experience is inevitable in daily life. Crowd managers need tools to accurately estimate the psychological aspects of crowds, an important one being crowd emotion. In this study, we explore the feasibility of obtaining a real-time, dynamic map of crowd emotions through self-reporting by crowd

  12. German crowd-investing platforms: Literature review and survey

    OpenAIRE

    Grundy, David; Ohmer, Carolina

    2016-01-01

    This article presents a comprehensive overview of the current German crowd-investing market drawing on a data-set of 31 crowd-investing platforms including the analysis of 265 completed projects. While crowd-investing market still only represents a niche in the German venture capital market, there is potential for an increase in both market volume and in average project investment. The market share is distributed among a few crowd-investing platforms with high entry barriers for new platforms...

  13. Crowds, not Drones: Modeling Human Factors in Interactive Crowdsourcing

    OpenAIRE

    Basu Roy, Senjuti; Lykourentzou, Ioanna; Thirumuruganathan, Saravanan; Amer-Yahia, Sihem; Das, Gautam

    2013-01-01

    International audience; In this vision paper, we propose SmartCrowd, an intelligent and adaptive crowdsourcing framework. Contrary to existing crowdsourcing systems, where the process of hiring workers (crowd), learning their skills, and evaluating the accuracy of tasks they perform are fragmented, siloed, and often ad-hoc, SmartCrowd foresees a paradigm shift in that process, considering unpredictability of human nature, namely human factors. SmartCrowd offers opportunities in making crowdso...

  14. Structure of metaphase chromosomes: a role for effects of macromolecular crowding.

    Science.gov (United States)

    Hancock, Ronald

    2012-01-01

    In metaphase chromosomes, chromatin is compacted to a concentration of several hundred mg/ml by mechanisms which remain elusive. Effects mediated by the ionic environment are considered most frequently because mono- and di-valent cations cause polynucleosome chains to form compact ~30-nm diameter fibres in vitro, but this conformation is not detected in chromosomes in situ. A further unconsidered factor is predicted to influence the compaction of chromosomes, namely the forces which arise from crowding by macromolecules in the surrounding cytoplasm whose measured concentration is 100-200 mg/ml. To mimic these conditions, chromosomes were released from mitotic CHO cells in solutions containing an inert volume-occupying macromolecule (8 kDa polyethylene glycol, 10.5 kDa dextran, or 70 kDa Ficoll) in 100 µM K-Hepes buffer, with contaminating cations at only low micromolar concentrations. Optical and electron microscopy showed that these chromosomes conserved their characteristic structure and compaction, and their volume varied inversely with the concentration of a crowding macromolecule. They showed a canonical nucleosomal structure and contained the characteristic proteins topoisomerase IIα and the condensin subunit SMC2. These observations, together with evidence that the cytoplasm is crowded in vivo, suggest that macromolecular crowding effects should be considered a significant and perhaps major factor in compacting chromosomes. This model may explain why ~30-nm fibres characteristic of cation-mediated compaction are not seen in chromosomes in situ. Considering that crowding by cytoplasmic macromolecules maintains the compaction of bacterial chromosomes and has been proposed to form the liquid crystalline chromosomes of dinoflagellates, a crowded environment may be an essential characteristic of all genomes.

  15. A Computational Model of Crowds for Collective Intelligence

    OpenAIRE

    Prpic, John; Jackson, Piper; Nguyen, Thai

    2014-01-01

    In this work, we present a high-level computational model of IT-mediated crowds for collective intelligence. We introduce the Crowd Capital perspective as an organizational-level model of collective intelligence generation from IT-mediated crowds, and specify a computational system including agents, forms of IT, and organizational knowledge.

  16. The Crowd in Requirements Engineering: The Landscape and Challenges

    NARCIS (Netherlands)

    Groen, Eduard C.; Seyff, Norbert; Ali, Raian; Dalpiaz, Fabiano|info:eu-repo/dai/nl/369508394; Doerr, Joerg; Guzman, Emitza; Hosseini, Mahmood; Marco, Jordi; Oriol, Marc; Perini, Anna; Stade, Melanie

    2017-01-01

    Crowd-based requirements engineering (CrowdRE) could significantly change RE. Performing RE activities such as elicitation with the crowd of stakeholders turns RE into a participatory effort, leads to more accurate requirements, and ultimately boosts software quality. Although any stakeholder in the

  17. The Behavioral Effects of Crowding: Definitions and Methods.

    Science.gov (United States)

    Dean, Larry M.; And Others

    1978-01-01

    Crews of 18 U.S. Navy combat vessels rated their living and working conditions aboard ship, including degree of crowding. Three different types of measures corresponding to different definitions of crowding were constructed. These separate crowding measures correlated uniquely with satisfaction and illness criteria. (Author/MA)

  18. Using the crowd as an innovation partner.

    Science.gov (United States)

    Boudreau, Kevin J; Lakhani, Karim R

    2013-04-01

    From Apple to Merck to Wikipedia, more and more organizations are turning to crowds for help in solving their most vexing innovation and research questions, but managers remain understandably cautious. It seems risky and even unnatural to push problems out to vast groups of strangers distributed around the world, particularly for companies built on a history of internal innovation. How can intellectual property be protected? How can a crowd-sourced solution be integrated into corporate operations? What about the costs? These concerns are all reasonable, the authors write, but excluding crowdsourcing from the corporate innovation tool kit means losing an opportunity. After a decade of study, they have identified when crowds tend to outperform internal organizations (or not). They outline four ways to tap into crowd-powered problem solving--contests, collaborative communities, complementors, and labor markets--and offer a system for picking the best one in a given situation. Contests, for example, are suited to highly challenging technical, analytical, and scientific problems; design problems; and creative or aesthetic projects. They are akin to running a series of independent experiments that generate multiple solutions--and if those solutions cluster at some extreme, a company can gain insight into where a problem's "technical frontier" lies. (Internal R&D may generate far less information.)

  19. Some Implications of Our Crowded Prisons.

    Science.gov (United States)

    Barry, John R.

    1986-01-01

    Reviews the March 1985 issue of the Annals of the American Academy of Political Science (vol. 478, pp.9-182) in which 18 authors describe and discuss various aspects of the problem of crowding in prisons and jails of the United States. (ABB)

  20. Membrane Shape Instability Induced by Protein Crowding.

    Science.gov (United States)

    Chen, Zhiming; Atefi, Ehsan; Baumgart, Tobias

    2016-11-01

    Peripheral proteins can bend membranes through several different mechanisms, including scaffolding, wedging, oligomerization, and crowding. The crowding effect in particular has received considerable attention recently, in part because it is a colligative mechanism-implying that it could, in principle, be explored by any peripheral protein. Here we sought to clarify to what extent this mechanism is exploited by endocytic accessory proteins. We quantitatively investigate membrane curvature generation by means of a GUV shape stability assay. We found that the amount of crowding required to induce membrane curvature is correlated with membrane tension. Importantly, we also revealed that at the same membrane tension, the crowding mechanism requires far higher protein coverage to induce curvature changes compared to those observed for the endophilin BAR domain, serving here as an example of an endocytic accessory protein. Our results are important for the design of membrane-targeted biosensors as well as the understanding of mechanisms of biological membrane shaping. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. The crowd in the Occupy movement

    NARCIS (Netherlands)

    Ossewaarde, Marinus R.R.

    2013-01-01

    In this article, I recast Elias Canetti's notion of crowds by placing it in the framework provided by Friedrich Nietzsche's Heraclitean dialectic of Apollonian and Dionysian opposites. The argument is introduced that, in European societies, the forms of social existence are mainly Apollonian,

  2. CrowdWater: a new smartphone app for crowd-based data collection in hydrology

    Science.gov (United States)

    Seibert, Jan; Strobl, Barbara; Etter, Simon; Vis, Marc; (Ilja) van Meerveld, H. J.

    2017-04-01

    The project CrowdWater (www.crowdwater.ch) explores opportunities for public involvement in hydrological observations. The project uses a "geocaching" type approach with the help of smartphones. Citizens can find existing sites and participate in the collection of hydrological data (stream water level, streamflow and soil moisture) using a smartphone app. The app also allows citizens to set up new sites. On this poster we present and discuss the first version of the CrowdWater app.

  3. Modelling crowd-bridge dynamic interaction with a discretely defined crowd

    Science.gov (United States)

    Carroll, S. P.; Owen, J. S.; Hussein, M. F. M.

    2012-05-01

    This paper presents a novel method of modelling crowd-bridge interaction using discrete element theory (DET) to model the pedestrian crowd. DET, also known as agent-based modelling, is commonly used in the simulation of pedestrian movement, particularly in cases where building evacuation is critical or potentially problematic. Pedestrians are modelled as individual elements subject to global behavioural rules. In this paper a discrete element crowd model is coupled with a dynamic bridge model in a time-stepping framework. Feedback takes place between both models at each time-step. An additional pedestrian stimulus is introduced that is a function of bridge lateral dynamic behaviour. The pedestrians' relationship with the vibrating bridge as well as the pedestrians around them is thus simulated. The lateral dynamic behaviour of the bridge is modelled as a damped single degree of freedom (SDoF) oscillator. The excitation and mass enhancement of the dynamic system is determined as the sum of individual pedestrian contributions at each time-step. Previous crowd-structure interaction modelling has utilised a continuous hydrodynamic crowd model. Limitations inherent in this modelling approach are identified and results presented that demonstrate the ability of DET to address these limitations. Simulation results demonstrate the model's ability to consider low density traffic flows and inter-subject variability. The emergence of the crowd's velocity-density relationship is also discussed.

  4. Perceptual Learning in Children With Infantile Nystagmus: Effects on Visual Performance

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.; Goossens, J.

    2016-01-01

    PURPOSE: To evaluate whether computerized training with a crowded or uncrowded letter-discrimination task reduces visual impairment (VI) in 6- to 11-year-old children with infantile nystagmus (IN) who suffer from increased foveal crowding, reduced visual acuity, and reduced stereopsis. METHODS:

  5. Crowded growth leads to the spontaneous evolution of semistable coexistence in laboratory yeast populations.

    Science.gov (United States)

    Frenkel, Evgeni M; McDonald, Michael J; Van Dyken, J David; Kosheleva, Katya; Lang, Gregory I; Desai, Michael M

    2015-09-08

    Identifying the mechanisms that create and maintain biodiversity is a central challenge in biology. Stable diversification of microbial populations often requires the evolution of differences in resource utilization. Alternatively, coexistence can be maintained by specialization to exploit spatial heterogeneity in the environment. Here, we report spontaneous diversification maintained by a related but distinct mechanism: crowding avoidance. During experimental evolution of laboratory Saccharomyces cerevisiae populations, we observed the repeated appearance of "adherent" (A) lineages able to grow as a dispersed film, in contrast to their crowded "bottom-dweller" (B) ancestors. These two types stably coexist because dispersal reduces interference competition for nutrients among kin, at the cost of a slower maximum growth rate. This tradeoff causes the frequencies of the two types to oscillate around equilibrium over the course of repeated cycles of growth, crowding, and dispersal. However, further coevolution of the A and B types can perturb and eventually destroy their coexistence over longer time scales. We introduce a simple mathematical model of this "semistable" coexistence, which explains the interplay between ecological and evolutionary dynamics. Because crowded growth generally limits nutrient access in biofilms, the mechanism we report here may be broadly important in maintaining diversity in these natural environments.

  6. A Bio-Inspired, Motion-Based Analysis of Crowd Behavior Attributes Relevance to Motion Transparency, Velocity Gradients, and Motion Patterns

    Science.gov (United States)

    Raudies, Florian; Neumann, Heiko

    2012-01-01

    The analysis of motion crowds is concerned with the detection of potential hazards for individuals of the crowd. Existing methods analyze the statistics of pixel motion to classify non-dangerous or dangerous behavior, to detect outlier motions, or to estimate the mean throughput of people for an image region. We suggest a biologically inspired model for the analysis of motion crowds that extracts motion features indicative for potential dangers in crowd behavior. Our model consists of stages for motion detection, integration, and pattern detection that model functions of the primate primary visual cortex area (V1), the middle temporal area (MT), and the medial superior temporal area (MST), respectively. This model allows for the processing of motion transparency, the appearance of multiple motions in the same visual region, in addition to processing opaque motion. We suggest that motion transparency helps to identify “danger zones” in motion crowds. For instance, motion transparency occurs in small exit passages during evacuation. However, motion transparency occurs also for non-dangerous crowd behavior when people move in opposite directions organized into separate lanes. Our analysis suggests: The combination of motion transparency and a slow motion speed can be used for labeling of candidate regions that contain dangerous behavior. In addition, locally detected decelerations or negative speed gradients of motions are a precursor of danger in crowd behavior as are globally detected motion patterns that show a contraction toward a single point. In sum, motion transparency, image speeds, motion patterns, and speed gradients extracted from visual motion in videos are important features to describe the behavioral state of a motion crowd. PMID:23300930

  7. Employment transitions in the Netherlands, 1980–2004: Are low educated men subject to structural or cyclical crowding out?

    NARCIS (Netherlands)

    Gesthuizen, M.J.W.; Wolbers, M.H.J.

    2010-01-01

    This article addresses whether low educated men are displaced from their jobs by higher educated workers in the Netherlands in the period 1980–2004. In particular, we test whether structural or cyclical crowding out is predominant in the Dutch labor market. In order to do so, we try to explain the

  8. Employment transitions in the Netherlands, 1980-2004 : are low-educated men subject to structural or cyclical crowding out?

    NARCIS (Netherlands)

    Gesthuizen, M.; Wolbers, M.H.J.

    2010-01-01

    This article addresses whether low educated men are displaced from their jobs by higher educated workers in the Netherlands in the period 1980–2004. In particular, we test whether structural or cyclical crowding out is predominant in the Dutch labor market. In order to do so, we try to explain the

  9. Crowd gathers for phantom particles

    CERN Multimedia

    2006-01-01

    The CNGS team set up models to demonstrate the oscillation of neutrinos...... and brought prototypes and equipment to explain how to manufacture a beam of neutrinos and send it a distance of 730 km! (Above: A scientist explains the methods to observe the position of protons.) There was a record attendance at the last Discovery Monday! Neutrinos and the CNGS facility (CERN Neutrinos to Gran Sasso) attracted some 300 visitors to the Microcosm. The success was well deserved as the CNGS team, which is close to bringing the project into service at the end of May, put forth great effort and imagination to interest the general public. A dozen physicists and engineers were stationed at six stands with models and posters. The OPERA collaboration from the Gran Sasso National Laboratory took part in the event with a stand presenting the experiments that will try to collect the neutrinos in Italy. A big thank-you to the CNGS and OPERA teams for this success! Come to the next Discovery Monday on 8 Mayto discover how ...

  10. Standing out in the crowd

    DEFF Research Database (Denmark)

    Bialkova, Svetlana; Grunert, Klaus G; Trijp, Hans van

    2013-01-01

    Whether and how information density on front-of-pack design affects consumers’ attention for nutrition labels is explored. The main manipulation concerned the number and type of nutrition labels (directive-, semi-, and non-directive), chromaticity (monochrome vs. traffic light color-coded scheme......); number and type of additional design elements; and the distance between the label and additional design elements. Attention was measured by performance in visual search task. Performance was slower with increasing number of additional design elements, and when the label appeared in a dense rather than...... non-dense area. These effects were modulated by label type and chromaticity. The results show that information density is a key factor for consumer attention to (nutrition) information. Implications for policy makers and food producers who want to optimize package design layout and thus help consumers...

  11. Microscopic information processing and communication in crowd dynamics

    Science.gov (United States)

    Henein, Colin Marc; White, Tony

    2010-11-01

    Due, perhaps, to the historical division of crowd dynamics research into psychological and engineering approaches, microscopic crowd models have tended toward modelling simple interchangeable particles with an emphasis on the simulation of physical factors. Despite the fact that people have complex (non-panic) behaviours in crowd disasters, important human factors in crowd dynamics such as information discovery and processing, changing goals and communication have not yet been well integrated at the microscopic level. We use our Microscopic Human Factors methodology to fuse a microscopic simulation of these human factors with a popular microscopic crowd model. By tightly integrating human factors with the existing model we can study the effects on the physical domain (movement, force and crowd safety) when human behaviour (information processing and communication) is introduced. In a large-room egress scenario with ample exits, information discovery and processing yields a crowd of non-interchangeable individuals who, despite close proximity, have different goals due to their different beliefs. This crowd heterogeneity leads to complex inter-particle interactions such as jamming transitions in open space; at high crowd energies, we found a freezing by heating effect (reminiscent of the disaster at Central Lenin Stadium in 1982) in which a barrier formation of naïve individuals trying to reach blocked exits prevented knowledgeable ones from exiting. Communication, when introduced, reduced this barrier formation, increasing both exit rates and crowd safety.

  12. Measures of crowding in the emergency department: a systematic review.

    Science.gov (United States)

    Hwang, Ula; McCarthy, Melissa L; Aronsky, Dominik; Asplin, Brent; Crane, Peter W; Craven, Catherine K; Epstein, Stephen K; Fee, Christopher; Handel, Daniel A; Pines, Jesse M; Rathlev, Niels K; Schafermeyer, Robert W; Zwemer, Frank L; Bernstein, Steven L

    2011-05-01

    Despite consensus regarding the conceptual foundation of crowding, and increasing research on factors and outcomes associated with crowding, there is no criterion standard measure of crowding. The objective was to conduct a systematic review of crowding measures and compare them in conceptual foundation and validity. This was a systematic, comprehensive review of four medical and health care citation databases to identify studies related to crowding in the emergency department (ED). Publications that "describe the theory, development, implementation, evaluation, or any other aspect of a 'crowding measurement/definition' instrument (qualitative or quantitative)" were included. A "measurement/definition" instrument is anything that assigns a value to the phenomenon of crowding in the ED. Data collected from papers meeting inclusion criteria were: study design, objective, crowding measure, and evidence of validity. All measures were categorized into five measure types (clinician opinion, input factors, throughput factors, output factors, and multidimensional scales). All measures were then indexed to six validation criteria (clinician opinion, ambulance diversion, left without being seen (LWBS), times to care, forecasting or predictions of future crowding, and other). There were 2,660 papers identified by databases; 46 of these papers met inclusion criteria, were original research studies, and were abstracted by reviewers. A total of 71 unique crowding measures were identified. The least commonly used type of crowding measure was clinician opinion, and the most commonly used were numerical counts (number or percentage) of patients and process times associated with patient care. Many measures had moderate to good correlation with validation criteria. Time intervals and patient counts are emerging as the most promising tools for measuring flow and nonflow (i.e., crowding), respectively. Standardized definitions of time intervals (flow) and numerical counts (nonflow

  13. HEPS challenges the wisdom of the crowds: the PEAK-Box Game. Try it yourself!

    Science.gov (United States)

    Zappa, Massimiliano; Liechti, Kaethi; Pappenberger, Florian; van Andel, Schalk Jan; Ramos, Maria-Helena

    2014-05-01

    In many situations the wisdom of the crowds (Galton, 1907) demonstrated to be superior to the estimation of single individuals. This is maybe one of the reasons why operational hydrometeorological services are more and more recognizing the added value given by ensemble prediction systems. A crowd of members has more wisdom than a single model output. Following a recent tradition, this year a game will also be played during the session on "Ensemble hydro-meteorological forecasting". During this presentation, the crowd attending the session will be asked to estimate the outcome of a probabilistic prediction system and to perform better than the Peak-Box approach. The "Peak-Box" is a novel visual support that can be communicated alongside with ensemble discharge forecasts (Zappa et al., 2013). This visual solution should provide support in the assessment of actions relying on accurate estimation of peak-timings and peak-flows. Results will be presented and discussed together with the participants of the session. Furthermore a blog post will appear later on www.hepex.org. References: Galton F. 1907.Vox populi. Nature 75: 450-451. Zappa M, Fundel F, Jaun S. 2013. A "Peak-Flow Box" Approach for Supporting Interpretation and Evaluation of Operational Ensemble Flood Forecasts. Hydrological processes. 27: 117-131. doi:/10.1002/hyp.9521

  14. Unified regression model of binding equilibria in crowded environments

    Science.gov (United States)

    Lee, Byoungkoo; LeDuc, Philip R.; Schwartz, Russell

    2011-01-01

    Molecular crowding is a critical feature distinguishing intracellular environments from idealized solution-based environments and is essential to understanding numerous biochemical reactions, from protein folding to signal transduction. Many biochemical reactions are dramatically altered by crowding, yet it is extremely difficult to predict how crowding will quantitatively affect any particular reaction systems. We previously developed a novel stochastic off-lattice model to efficiently simulate binding reactions across wide parameter ranges in various crowded conditions. We now show that a polynomial regression model can incorporate several interrelated parameters influencing chemistry under crowded conditions. The unified model of binding equilibria accurately reproduces the results of particle simulations over a broad range of variation of six physical parameters that collectively yield a complicated, non-linear crowding effect. The work represents an important step toward the long-term goal of computationally tractable predictive models of reaction chemistry in the cellular environment. PMID:22355615

  15. Where are you going? An agent inclusive approach for path predictions in crowd

    Science.gov (United States)

    Li, Yuke; Shen, Weiming

    2017-07-01

    Pedestrian path forecasting is one of the recently emerging applications in visual crowd analysis and modeling. Moreover, of the attempts proposed to date, only a few have considered that the undergoing interaction among agents is a key factor in determining their walking trends in a given scene. To this end, we propose a simple yet efficient framework for pedestrian path prediction in crowded scenes. First, we extract motion features related to the target pedestrian and its nearby neighbors. Second, we adopt an autoencoder feature-learning model to further enhance the representation of the extracted features. Finally, we utilize a Gaussian process regression model to infer the potential future trajectories of the target pedestrians given their walking history in the scene. We performed experiments using a challenging dataset, and our method yielded promising results and outperformed traditional methods proposed in the literature.

  16. Integrating pedestrian simulation, tracking and event detection for crowd analysis

    OpenAIRE

    Butenuth, Matthias; Burkert, Florian; Kneidl, Angelika; Borrmann, Andre; Schmidt, Florian; Hinz, Stefan; Sirmacek, Beril; Hartmann, Dirk

    2011-01-01

    In this paper, an overall framework for crowd analysis is presented. Detection and tracking of pedestrians as well as detection of dense crowds is performed on image sequences to improve simulation models of pedestrian flows. Additionally, graph-based event detection is performed by using Hidden Markov Models on pedestrian trajectories utilizing knowledge from simulations. Experimental results show the benefit of our integrated framework using simulation and real-world data for crowd anal...

  17. A generic method for evaluating crowding in the emergency department

    DEFF Research Database (Denmark)

    Eiset, Andreas Halgreen; Erlandsen, Mogens; Møllekær, Anders Brøns

    2016-01-01

    Background Crowding in the emergency department (ED) has been studied intensively using complicated non-generic methods that may prove difficult to implement in a clinical setting. This study sought to develop a generic method to describe and analyse crowding from measurements readily available......, a ‘carry over’ effect was shown between shifts and days. Conclusions The presented method offers an easy and generic way to get detailed insight into the dynamics of crowding in an ED. Keywords Crowding, Emergency department, ED, Generic, Method, Model, Queue, Patient flow...

  18. Simulation of Cognitive Pedestrian Agents Crowds in Crisis Situations

    Directory of Open Access Journals (Sweden)

    Margaret Lyell

    2006-06-01

    Full Text Available In crisis situations in an urban environment, first responder teams often must deal with crowds of people. Consider the case of a building fire in a dense city environment. People may be injured; walkways may be blocked, with fire equipment attempting to reach the scene. Crowd behavior can become an issue when trying to reach the injured, ensure safety and restore conditions to normal. The motivations of pedestrians that form the crowd can vary. Some are there because they are curious about the crisis situation. Others, attending to their individual concerns, may have found themselves in the 'wrong' location. They may be trying to leave the area, but the density of people as well as the spatial layout of the walkways may be impeding their progress. Other individuals, unaware of the fire, may be attempting to reach their intended destinations that happen to be near the crisis area, thus adding to crowd congestion. With a model of crowd behavior, effective strategies for resource usage in managing crowd behavior can be developed. Our approach to this problem is that of agent-based modeling and simulation. We develop a cognitive pedestrian agent model. Utilizing this model, we simulate crowd behavior in a 'city fire' scenario. Characteristics of crowd behavior with different pedestrian personality mixes and a strategy for crowd management are investigated

  19. Grouping and crowding affect target appearance over different spatial scales.

    Directory of Open Access Journals (Sweden)

    Bilge Sayim

    Full Text Available Crowding is the impairment of peripheral target perception by nearby flankers. A number of recent studies have shown that crowding shares many features with grouping. Here, we investigate whether effects of crowding and grouping on target perception are related by asking whether they operate over the same spatial scale. A target letter T had two sets of flanking Ts of varying orientations. The first set was presented close to the target, yielding strong crowding. The second set was either close enough to cause crowding on their own or too far to cause crowding on their own. The Ts of the second set had the same orientation that either matched the target's orientation (Grouped condition or not (Ungrouped condition. In Experiment 1, the Grouped flankers reduced crowding independently of their distance from the target, suggesting that grouping operated over larger distances than crowding. In Experiments 2 and 3 we found that grouping did not affect sensitivity but produced a strong bias to report that the grouped orientation was present at the target location whether or not it was. Finally, we investigated whether this bias was a response or perceptual bias, rejecting the former in favor of a perceptual grouping explanation. We suggest that the effect of grouping is to assimilate the target to the identity of surrounding flankers when they are all the same, and that this shape assimilation effect differs in its spatial scale from the integration effect of crowding.

  20. Crowd logistics: an opportunity for more sustainable urban freight transport?

    National Research Council Canada - National Science Library

    Buldeo Rai, Heleen; Verlinde, Sara; Merckx, Jan; Macharis, Cathy

    2017-01-01

    .... Within Crowd logistics (CL), delivery operations are carried out by using passengers’ excess capacity on journeys that are already taking place, resulting in economic, social and environmental benefits...

  1. Theory of Crowding Effects on Bimolecular Reaction Rates.

    Science.gov (United States)

    Berezhkovskii, Alexander M; Szabo, Attila

    2016-07-07

    An analytical expression for the rate constant of a diffusion-influenced bimolecular reaction in a crowded environment is derived in the framework of a microscopic model that accounts for: (1) the slowdown of diffusion due to crowding and the dependence of the diffusivity on the distance between the reactants, (2) a crowding-induced attractive short-range potential of mean force, and (3) nonspecific reversible binding to the crowders. This expression spans the range from reaction to diffusion control. Crowding can increase the reaction-controlled rate by inducing an effective attraction between reactants but decrease the diffusion-controlled rate by reducing their relative diffusivity.

  2. Life in a Crowd: Macromolecular Crowding and Confinement Effects on Protein Interactions in Living Systems

    Science.gov (United States)

    Cheung, Margaret

    2007-03-01

    Biological polymers carry out their functions in living systems where the environment is very concentrated or crowded by macromolecules. Physically, the composition of a cell is more than ``a sack of water''; its consistency is closer to Jell-O. Experiments suggests that, because of this macromolecular crowding effect that confines polymeric dynamics, the kinetics and thermodynamics of protein folding and the association rate constants of protein-protein interactions in a cell (in vivo) are very different from that ina diluted test tube (in vitro). In order to quantitatively understand macromolecular crowding and confinement effects on protein dynamics, we used coarse-grained models that physically captured interactions between crowders and a protein. The folding rates of a model protein nonmonotonically increased with the volume fraction of the crowders. At lower volume fractions, depletion-induced attractions from crowders could be mapped according to the spherical confinement model. A result of spherical confinement was the destabilization of denatured states by disallowing extended configurations that were longer than the pore size. However, at higher volume fractions, conformational fluctuations of a protein were susceptible to the shape of the confining condition. Thus, an approximation of the spherical confinement to mimic crowding effects was no longer effective.

  3. The Financial Impact of Emergency Department Crowding

    Directory of Open Access Journals (Sweden)

    Foley, Mathew

    2011-05-01

    Full Text Available Objective: The economic benefits of reducing emergency department (ED crowding are potentially substantial as they may decrease hospital length of stay. Hospital administrators and public officials may therefore be motivated to implement crowding protocols. We sought to identify a potential cost of ED crowding by evaluating the contribution of excess ED length of stay (LOS to overall hospital length of stay. Methods: We performed a retrospective review of administrative data of adult patients from two urban hospitals (one county and one university in Brooklyn, New York from 2006-2007. Data was provided by each facility. Extrapolating from prior research (Krochmal and Riley, 2005, we determined the increase in total hospital LOS due to extended ED lengths of stay, and applied cost and charge analyses for the two separate facilities. Results: We determined that 6,205 (5.0% admitted adult patients from the county facility and 3,017 (3.4% patients from the university facility were held in the ED greater than one day over a one-year period. From prior research, it has been estimated that each of these patient’s total hospital length of stay was increased on average by 11.7% (0.61 days at the county facility, and 0.71 days at the university facility. The increased charges over one year at the county facility due to the extended ED LOS was therefore approximately $9.8 million, while the increased costs at the university facility were approximately $3.9 million. Conclusion: Based on extrapolations from Krochmal and Riley applied to two New York urban hospitals, the county hospital could potentially save $9.8 million in charges and the university hospital $3.9 million in costs per year if they eliminate ED boarding of adult admitted patients by improving movement to the inpatient setting. [West J Emerg Med. 2011;12(2:192-197.

  4. Modelling asymmetric growth in crowded plant communities

    DEFF Research Database (Denmark)

    Damgaard, Christian

    2010-01-01

    A class of models that may be used to quantify the effect of size-asymmetric competition in crowded plant communities by estimating a community specific degree of size-asymmetric growth for each species in the community is suggested. The model consists of two parts: an individual size......-asymmetric growth part, where growth is assumed to be proportional to a power function of the size of the individual, and a term that reduces the relative growth rate as a decreasing function of the individual plant size and the competitive interactions from other plants in the neighbourhood....

  5. Should we add visual acuity ratios to referral criteria for potential cerebral visual impairment?

    Science.gov (United States)

    van der Zee, Ymie J; Stiers, Peter; Evenhuis, Heleen M

    To determine whether the assessment of visual acuity ratios might improve the referral of children with (sub)normal visual acuity but at risk of cerebral visual impairment. In an exploratory study, we assessed visual acuity, crowding ratio and the ratios between grating acuity (Teller Acuity Cards-II) and optotype acuity (Cambridge Crowding Cards) in 60 typically developing school children (mean age 5y8m±1y1m), 21 children with ocular abnormalities only (5y7m±1y9m) and 26 children with (suspected) brain damage (5y7m±1y11m). Sensitivities and specificities were calculated for targets and controls from the perspective of different groups of diagnosticians: youth health care professionals (target: children with any visual abnormalities), ophthalmologists and low vision experts (target: children at risk of cerebral visual impairment). For youth health care professionals subnormal visual acuity had the best sensitivity (76%) and specificity (70%). For ophthalmologists and low vision experts the crowding ratio had the best sensitivity (67%) and specificity (79 and 86%). Youth health care professionals best continue applying subnormal visual acuity for screening, whereas ophthalmologists and low vision experts best add the crowding ratio to their routine diagnostics, to distinguish children at risk of visual impairment in the context of brain damage from children with ocular pathology only. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  6. The power of crowding for the origins of life.

    Science.gov (United States)

    Hansma, Helen Greenwood

    2014-12-01

    Molecular crowding increases the likelihood that life as we know it would emerge. In confined spaces, diffusion distances are shorter, and chemical reactions produce fewer and more regular products. Crowding will occur in the spaces between Muscovite mica sheets, which has many advantages as a site for life's origins.

  7. Game theoretic aspects of crowd renting | Nwobi-Okoye | Science ...

    African Journals Online (AJOL)

    Politicians and businessmen use various strategies to outwit their opponents. One such strategy is crowd renting, a powerful virtual strategy. A mathematical model developed by Nwobi-Okoye using game theory is used to show that crowd renting would always be the equilibrium strategy in strategic interactions involving ...

  8. Navigation for Characters and Crowds in Complex Virtual Environments

    NARCIS (Netherlands)

    van Toll, W.G.|info:eu-repo/dai/nl/35269288X

    2017-01-01

    In a crowd simulation, virtual walking characters need to compute and traverse paths through a virtual environment while avoiding collisions. Simulations of large crowds occur increasingly often in computer games, in which real-time performance is required. Also, there is an increasing demand for

  9. Locus of Peer Influence: Social Crowd and Best Friend.

    Science.gov (United States)

    Urberg, Kathryn A.

    1992-01-01

    The relative influence of best friends and social crowds of 324 older adolescents (eleventh graders) on cigarette smoking was examined to determine influences as a function of sex, conformity, and friendship mutuality. Best friends, rather than social crowd, appeared to be the major influence in this group. (SLD)

  10. The Wisdom of the Crowd in Combinatorial Problems

    Science.gov (United States)

    Yi, Sheng Kung Michael; Steyvers, Mark; Lee, Michael D.; Dry, Matthew J.

    2012-01-01

    The "wisdom of the crowd" phenomenon refers to the finding that the aggregate of a set of proposed solutions from a group of individuals performs better than the majority of individual solutions. Most often, wisdom of the crowd effects have been investigated for problems that require single numerical estimates. We investigate whether the effect…

  11. Designing for crowd well-being : Needs and design suggestions

    NARCIS (Netherlands)

    Li, J.; De Ridder, H.; Vermeeren, A.P.O.S.; Conrado, C.; Martella, C.

    2013-01-01

    This paper investigates the needs or criteria for sustaining well-being in crowded situations through two focus group discussions with a total of ten participants. We conclude that pursuing crowd well-being could be divided into two different cases: one is obtaining the enhancement of the current

  12. Households' ethnic background and crowding in public housing ...

    African Journals Online (AJOL)

    Households' ethnic background and crowding in public housing multifamily apartments in Lagos. ... varies considerably according to ethnic groups. It recommends that ethnic groups should be deliberately mixed to achieve ethnic and social integration. Keywords: crowding, ethnicity, multifamily apartment, public housing ...

  13. Fluorescence Dynamics of a FRET Probe Designed for Crowding Studies

    NARCIS (Netherlands)

    Currie, Megan; Leopold, Hannah; Schwarz, Jacob; Boersma, Arnold J; Sheets, Erin D; Heikal, Ahmed A

    2017-01-01

    Living cells are crowded with macromolecules and organelles. As a result, there is an urgent need for molecular sensors for quantitative, site-specific assessment of the macromolecular crowding effects on a myriad of biochemical processes toward quantitative cell biology and biophysics. Here we

  14. Gender differences in the perception of crowd perception

    Directory of Open Access Journals (Sweden)

    Yang eBai

    2015-09-01

    Full Text Available In this study, we investigated whether the first impression of a crowd of faces—crowd perception—is influenced by social background and cognitive processing. Specifically, we explored whether males and females, two groups that are distinct biologically and socially, differ in their ability to extract ensemble characteristics from crowds of faces that were comprised of different identities. Participants were presented with crowds of similar faces and were instructed to scroll through a morphed continuum of faces until they found a face that was representative of the average identity of each crowd. Consistent with previous research, females were more precise in single face perception. Furthermore, the results showed that females were generally more accurate in estimating the average identity of a crowd. However, the correlation between single face discrimination and crowd averaging differed between males and females. Specifically, male subjects’ ensemble integration superiority slightly compensated for their poor single face perception; their performance on the crowd perception task was not as poor as would be expected from their single face discrimination ability. Overall, the results suggest that group perception is not an isolated or uniform cognitive mechanism, but rather one that interacts with biological and social processes.

  15. Anomaly detection and localization in crowded scenes.

    Science.gov (United States)

    Li, Weixin; Mahadevan, Vijay; Vasconcelos, Nuno

    2014-01-01

    The detection and localization of anomalous behaviors in crowded scenes is considered, and a joint detector of temporal and spatial anomalies is proposed. The proposed detector is based on a video representation that accounts for both appearance and dynamics, using a set of mixture of dynamic textures models. These models are used to implement 1) a center-surround discriminant saliency detector that produces spatial saliency scores, and 2) a model of normal behavior that is learned from training data and produces temporal saliency scores. Spatial and temporal anomaly maps are then defined at multiple spatial scales, by considering the scores of these operators at progressively larger regions of support. The multiscale scores act as potentials of a conditional random field that guarantees global consistency of the anomaly judgments. A data set of densely crowded pedestrian walkways is introduced and used to evaluate the proposed anomaly detector. Experiments on this and other data sets show that the latter achieves state-of-the-art anomaly detection results.

  16. German crowd-investing platforms: Literature review and survey

    Directory of Open Access Journals (Sweden)

    David Grundy

    2016-12-01

    Full Text Available This article presents a comprehensive overview of the current German crowd-investing market drawing on a data-set of 31 crowd-investing platforms including the analysis of 265 completed projects. While crowd-investing market still only represents a niche in the German venture capital market, there is potential for an increase in both market volume and in average project investment. The market share is distributed among a few crowd-investing platforms with high entry barriers for new platforms although platforms that specialise in certain sectors have managed to successfully enter the market. German crowd-investing platforms are found to promote mainly internet-based enterprises (36% followed by projects in real estate (24% and green projects (19%, with the median money raised 100,000 euro.

  17. Understanding consumer's responses to negative emotions related to crowding on satisfaction and impulse purchase in retail: the mediating role of coping

    Directory of Open Access Journals (Sweden)

    Marlette Cassia Oliveira Ferreira

    Full Text Available Abstract The perception of crowding, understood as an individual's response to crowds, can be observed in retail environments and influences positive and negative emotions. In this research we test the mediating effect of coping – rational strategies adopted to deal with negative emotions – in the relationship between negative emotions (resulting from crowding perception and consumer behavior (measured by impulse purchase and satisfaction. The findings related to coping explain to what extent there is a positive response to human density in the retail environment. For this, a theoretical model was developed which includes the relationships among perception of crowding, positive and negative emotions, and consumer behavior. The model enhances the understanding of the crowding phenomenon by including relationships mediated by an oppositional strategy (coping dimension between negative emotions and consumer behaviors. To test the theoretical model, a survey was conducted with 456 respondents and hypothesis tests using structural equation modeling. It was evidenced that crowding perception has more robust effects on negative emotions than positive emotions. It is emphasized that with the inclusion of opposition mediation, the weak direct relationship between negative emotions and behaviors, becomes a positive relationship between negative emotion and impulse purchase, and negative emotion and satisfaction. In addition to the theoretical contributions of the tested model, future research and managerial implications are proposed at the end of the article.

  18. Asynchronous dentofacial development and dental crowding: a cross-sectional study in a contemporary sample of children in France.

    Science.gov (United States)

    Yan-Vergnes, Wei; Vergnes, Jean-Noel; Dumoncel, Jean; Baron, Pascal; Marchal-Sixou, Christine; Braga, José

    2013-11-19

    The causes of dental crowding are not fully understood, but it may result from an evolutionary trend towards reduced facial volume, without a proportional reduction in tooth sizes. Most previous studies conducted among modern humans have revealed a very low or non-existent correlation between tooth size and jaw size. Cross-comparison between dental age and facial skeletal age could help to provide better knowledge of the dynamic process of dental crowding. The primary objective of this research was to study the synchronism of dental maturation and skeletal facial growth in a sample of modern children living in France. The secondary objective was to assess the link between dentofacial asynchronism and dental crowding. The random sample comprised 28 subjects (16 girls, 12 boys). Mean chronological age was 13.5 years (± 2.1; range 9.2-17.6). Mean dental age was 14.2 years (± 2.8; range 7.5-17) and mean facial skeletal age was 12.8 years (± 2.6, range 7-22). In the estimations of dental age and facial skeletal age, there was no evidence of systematic bias. There were 10 subjects (9 girls, 1 boy) with asynchronous dentofacial development. Finally, there were 13 subjects (8 girls, 5 boys) with dental crowding. A significant association was found between delayed facial skeletal growth/advanced dental maturation and dental crowding (P = 0.01). Dental maturation and facial growth are not necessarily synchronous. Further understanding of the interactions between dental maturation and facial growth could have crucial implications in biological anthropology, as well as for the clinical practice of orthodontists. From an anthropological perspective, this study suggests that asynchronous dentofacial development could, at least partially, explain the frequency of dental crowding in modern populations.

  19. Visual agnosia.

    Science.gov (United States)

    Álvarez, R; Masjuan, J

    2016-03-01

    Visual agnosia is defined as an impairment of object recognition, in the absence of visual acuity or cognitive dysfunction that would explain this impairment. This condition is caused by lesions in the visual association cortex, sparing primary visual cortex. There are 2 main pathways that process visual information: the ventral stream, tasked with object recognition, and the dorsal stream, in charge of locating objects in space. Visual agnosia can therefore be divided into 2 major groups depending on which of the two streams is damaged. The aim of this article is to conduct a narrative review of the various visual agnosia syndromes, including recent developments in a number of these syndromes. Copyright © 2015 Elsevier España, S.L.U. y Sociedad Española de Medicina Interna (SEMI). All rights reserved.

  20. The contrasting effect of macromolecular crowding on amyloid fibril formation.

    Directory of Open Access Journals (Sweden)

    Qian Ma

    Full Text Available Amyloid fibrils associated with neurodegenerative diseases can be considered biologically relevant failures of cellular quality control mechanisms. It is known that in vivo human Tau protein, human prion protein, and human copper, zinc superoxide dismutase (SOD1 have the tendency to form fibril deposits in a variety of tissues and they are associated with different neurodegenerative diseases, while rabbit prion protein and hen egg white lysozyme do not readily form fibrils and are unlikely to cause neurodegenerative diseases. In this study, we have investigated the contrasting effect of macromolecular crowding on fibril formation of different proteins.As revealed by assays based on thioflavin T binding and turbidity, human Tau fragments, when phosphorylated by glycogen synthase kinase-3β, do not form filaments in the absence of a crowding agent but do form fibrils in the presence of a crowding agent, and the presence of a strong crowding agent dramatically promotes amyloid fibril formation of human prion protein and its two pathogenic mutants E196K and D178N. Such an enhancing effect of macromolecular crowding on fibril formation is also observed for a pathological human SOD1 mutant A4V. On the other hand, rabbit prion protein and hen lysozyme do not form amyloid fibrils when a crowding agent at 300 g/l is used but do form fibrils in the absence of a crowding agent. Furthermore, aggregation of these two proteins is remarkably inhibited by Ficoll 70 and dextran 70 at 200 g/l.We suggest that proteins associated with neurodegenerative diseases are more likely to form amyloid fibrils under crowded conditions than in dilute solutions. By contrast, some of the proteins that are not neurodegenerative disease-associated are unlikely to misfold in crowded physiological environments. A possible explanation for the contrasting effect of macromolecular crowding on these two sets of proteins (amyloidogenic proteins and non-amyloidogenic proteins has been

  1. Gauging Through the Crowd: A Crowd-Sourcing Approach to Urban Rainfall Measurement and Storm Water Modeling Implications

    Science.gov (United States)

    Yang, Pan; Ng, Tze Ling

    2017-11-01

    Accurate rainfall measurement at high spatial and temporal resolutions is critical for the modeling and management of urban storm water. In this study, we conduct computer simulation experiments to test the potential of a crowd-sourcing approach, where smartphones, surveillance cameras, and other devices act as precipitation sensors, as an alternative to the traditional approach of using rain gauges to monitor urban rainfall. The crowd-sourcing approach is promising as it has the potential to provide high-density measurements, albeit with relatively large individual errors. We explore the potential of this approach for urban rainfall monitoring and the subsequent implications for storm water modeling through a series of simulation experiments involving synthetically generated crowd-sourced rainfall data and a storm water model. The results show that even under conservative assumptions, crowd-sourced rainfall data lead to more accurate modeling of storm water flows as compared to rain gauge data. We observe the relative superiority of the crowd-sourcing approach to vary depending on crowd participation rate, measurement accuracy, drainage area, choice of performance statistic, and crowd-sourced observation type. A possible reason for our findings is the differences between the error structures of crowd-sourced and rain gauge rainfall fields resulting from the differences between the errors and densities of the raw measurement data underlying the two field types.

  2. Eyes on crowding : Crowding is preserved when responding by eye and similarly affects identity and position accuracy

    NARCIS (Netherlands)

    Yildirim, Funda; Meyer, Vincent; Cornelissen, Frans W.

    Peripheral vision guides recognition and selection of targets for eye movements. Crowding-a decline in recognition performance that occurs when a potential target is surrounded by other, similar, objects-influences peripheral object recognition. A recent model study suggests that crowding may be due

  3. Perceiving emotion in crowds: the role of dynamic body postures on the perception of emotion in crowded scenes.

    Science.gov (United States)

    McHugh, Joanna Edel; McDonnell, Rachel; O'Sullivan, Carol; Newell, Fiona N

    2010-07-01

    Although the perception of emotion in individuals is an important social skill, very little is known about how emotion is determined from a crowd of individuals. We investigated the perception of emotion in scenes of crowds populated by dynamic characters each expressing an emotion. Facial expressions were masked in these characters and emotion was conveyed using body motion and posture only. We systematically varied the proportion of characters in each scene depicting one of two emotions and participants were required to categorise the overall emotion of the crowd. In Experiment 1, we found that the perception of emotions in a crowd is efficient even with relatively brief exposures of the crowd stimuli. Furthermore, the emotion of a crowd was generally determined by the relative proportions of characters conveying it, although we also found that some emotions dominated perception. In Experiment 2, we found that an increase in crowd size was not associated with a relative decrease in the efficiency with which the emotion was categorised. Our findings suggest that body motion is an important social cue in perceiving the emotion of crowds and have implications for our understanding of how we perceive social information from groups.

  4. The myopia of crowds: Cognitive load and collective evaluation of answers on Stack Exchange.

    Science.gov (United States)

    Burghardt, Keith; Alsina, Emanuel F; Girvan, Michelle; Rand, William; Lerman, Kristina

    2017-01-01

    Crowds can often make better decisions than individuals or small groups of experts by leveraging their ability to aggregate diverse information. Question answering sites, such as Stack Exchange, rely on the "wisdom of crowds" effect to identify the best answers to questions asked by users. We analyze data from 250 communities on the Stack Exchange network to pinpoint factors affecting which answers are chosen as the best answers. Our results suggest that, rather than evaluate all available answers to a question, users rely on simple cognitive heuristics to choose an answer to vote for or accept. These cognitive heuristics are linked to an answer's salience, such as the order in which it is listed and how much screen space it occupies. While askers appear to depend on heuristics to a greater extent than voters when choosing an answer to accept as the most helpful one, voters use acceptance itself as a heuristic, and they are more likely to choose the answer after it has been accepted than before that answer was accepted. These heuristics become more important in explaining and predicting behavior as the number of available answers to a question increases. Our findings suggest that crowd judgments may become less reliable as the number of answers grows.

  5. Quality improvement collaboratives and the wisdom of crowds : Spread explained by perceived success at group level

    NARCIS (Netherlands)

    Dückers, Michel L A; Groenewegen, Peter P.; Wagner, Cordula

    2014-01-01

    Background: Many studies have been conducted to evaluate the impact of quality improvement collaboratives (QICs) on the quality of healthcare. This article addresses an underexplored topic, namely the use of QICs as 'intentional spread strategy.' Its objective is to predict the dissemination of

  6. Quality improvement collaboratives and the wisdom of crowds: spread explained by perceived success at group level.

    NARCIS (Netherlands)

    Dückers, M.L.A.; Groenewegen, P.P.; Wagner, C.

    2014-01-01

    Background: Many studies have been conducted to evaluate the impact of quality improvement collaboratives (QICs) on the quality of healthcare. This article addresses an underexplored topic, namely the use of QICs as ‘intentional spread strategy.’ Its objective is to predict the dissemination of

  7. Relationship among Lower Arch Length, Arch Width and Arch Perimeter in Crowding and Non-Crowding Groups

    Directory of Open Access Journals (Sweden)

    Selmani Mimoza

    2015-03-01

    Full Text Available Crowding is one of the causes of class I malocclusion. The purpose of the present study was to examine the relationship between arch length, arch width and arch perimeter in crowded and non-crowded arches, as well as to made comparison of the right and left sides between them and to find out the contributing factor in lower arch crowding. The study groups consisted of 60 subjects aged 16 to 21 years. First group consisted of 30 pairs of dental study models with class I normal occlusion. The second group consisted of 30 pairs of study models with class I crowding. Measurements of arch length and width were made as defined by Lavelle and Foster, using Korkhaus callipers. Arch perimeter was measured by Lundstrom method’s using manual calliper with sharp points. Differences between these measurements were made by Mann-Whitney U test (Z/U.

  8. Reduced crowding and poor contour detection in schizophrenia are consistent with weak surround inhibition.

    Science.gov (United States)

    Robol, Valentina; Tibber, Marc S; Anderson, Elaine J; Bobin, Tracy; Carlin, Patricia; Shergill, Sukhwinder S; Dakin, Steven C

    2013-01-01

    Detection of visual contours (strings of small oriented elements) is markedly poor in schizophrenia. This has previously been attributed to an inability to group local information across space into a global percept. Here, we show that this failure actually originates from a combination of poor encoding of local orientation and abnormal processing of visual context. We measured the ability of observers with schizophrenia to localise contours embedded in backgrounds of differently oriented elements (either randomly oriented, near-parallel or near-perpendicular to the contour). In addition, we measured patients' ability to process local orientation information (i.e., report the orientation of an individual element) for both isolated and crowded elements (i.e., presented with nearby distractors). While patients are poor at detecting contours amongst randomly oriented elements, they are proportionally less disrupted (compared to unaffected controls) when contour and surrounding elements have similar orientations (near-parallel condition). In addition, patients are poor at reporting the orientation of an individual element but, again, are less prone to interference from nearby distractors, a phenomenon known as visual crowding. We suggest that patients' poor performance at contour perception arises not as a consequence of an "integration deficit" but from a combination of reduced sensitivity to local orientation and abnormalities in contextual processing. We propose that this is a consequence of abnormal gain control, a phenomenon that has been implicated in orientation-selectivity as well as surround suppression.

  9. Reduced crowding and poor contour detection in schizophrenia are consistent with weak surround inhibition.

    Directory of Open Access Journals (Sweden)

    Valentina Robol

    Full Text Available Detection of visual contours (strings of small oriented elements is markedly poor in schizophrenia. This has previously been attributed to an inability to group local information across space into a global percept. Here, we show that this failure actually originates from a combination of poor encoding of local orientation and abnormal processing of visual context.We measured the ability of observers with schizophrenia to localise contours embedded in backgrounds of differently oriented elements (either randomly oriented, near-parallel or near-perpendicular to the contour. In addition, we measured patients' ability to process local orientation information (i.e., report the orientation of an individual element for both isolated and crowded elements (i.e., presented with nearby distractors.While patients are poor at detecting contours amongst randomly oriented elements, they are proportionally less disrupted (compared to unaffected controls when contour and surrounding elements have similar orientations (near-parallel condition. In addition, patients are poor at reporting the orientation of an individual element but, again, are less prone to interference from nearby distractors, a phenomenon known as visual crowding.We suggest that patients' poor performance at contour perception arises not as a consequence of an "integration deficit" but from a combination of reduced sensitivity to local orientation and abnormalities in contextual processing. We propose that this is a consequence of abnormal gain control, a phenomenon that has been implicated in orientation-selectivity as well as surround suppression.

  10. Reduced Crowding and Poor Contour Detection in Schizophrenia Are Consistent with Weak Surround Inhibition

    Science.gov (United States)

    Robol, Valentina; Tibber, Marc S.; Anderson, Elaine J.; Bobin, Tracy; Carlin, Patricia; Shergill, Sukhwinder S.; Dakin, Steven C.

    2013-01-01

    Background Detection of visual contours (strings of small oriented elements) is markedly poor in schizophrenia. This has previously been attributed to an inability to group local information across space into a global percept. Here, we show that this failure actually originates from a combination of poor encoding of local orientation and abnormal processing of visual context. Methods We measured the ability of observers with schizophrenia to localise contours embedded in backgrounds of differently oriented elements (either randomly oriented, near-parallel or near-perpendicular to the contour). In addition, we measured patients’ ability to process local orientation information (i.e., report the orientation of an individual element) for both isolated and crowded elements (i.e., presented with nearby distractors). Results While patients are poor at detecting contours amongst randomly oriented elements, they are proportionally less disrupted (compared to unaffected controls) when contour and surrounding elements have similar orientations (near-parallel condition). In addition, patients are poor at reporting the orientation of an individual element but, again, are less prone to interference from nearby distractors, a phenomenon known as visual crowding. Conclusions We suggest that patients’ poor performance at contour perception arises not as a consequence of an “integration deficit” but from a combination of reduced sensitivity to local orientation and abnormalities in contextual processing. We propose that this is a consequence of abnormal gain control, a phenomenon that has been implicated in orientation-selectivity as well as surround suppression. PMID:23585865

  11. Crowded: a crowd-sourced perspective of events as they happen

    Science.gov (United States)

    Brantingham, Richard; Hossain, Aleem

    2013-05-01

    `Crowded' is a web-based application developed by the Defence Science & Technology Laboratory (Dstl) that collates imagery of a particular location from a variety of media sources to provide an operator with real-time situational awareness. Emergency services and other relevant agencies have detected or become aware of an event - a riot or an explosion, for instance - and its location or text associated with it. The ubiquity of mobile devices allows people to collect and upload media of the incident to the Internet, in real time. Crowded manages the interactions with online sources of media: Flickr; Instagram; YouTube; Twitter; and Transport for London traffic cameras, to retrieve imagery that is being uploaded at that point in time. In doing so, it aims to provide human operators with near-instantaneous `eyes-on' from a variety of different perspectives. The first instantiation of Crowded was implemented as a series of integrated web-services with the aim of rapidly understanding whether the approach was viable. In doing so, it demonstrated how non-traditional, open sources can be used to provide a richer current intelligence picture than can be obtained alone from classified sources. The development of Crowded also explored how open source technology and cloud-based services can be used in the modern intelligence and security environment to provide a multi-agency Common Operating Picture to help achieve a co-ordinated response. The lessons learned in building the prototype are currently being used to design and develop a second version, and identify options and priorities for future development.

  12. Global crowd data to understand risk taking behavior: Understanding the costs of crowd sourcing

    Science.gov (United States)

    Hendrikx, J.; Johnson, J.

    2016-12-01

    Crowd sourcing is an increasingly common approach to collect data from a large number of places, people, or both, for a given phenomenon or observation. It is often thought of as a very cost effective approach to collect data from large spatial domains, or from difficult to reach areas, or for spatially discrete observations. While crowd sourcing data can provide a wealth of data beyond that which most research teams can collect themselves, there are many associated, and sometime unexpected costs with this approach. We present a case study of a crowd-sourced data collection campaign to collect GPS tracks of back country recreationalists in avalanche terrain. We ask the volunteers to track their outings using the GPS on their smart phone using a free application, and on the completion of their trip email us their track. On receipt of this track we automatically reply with a link to a decision making survey. In this way we collect data on both the physical attributes of their trip, as well as the social, psychological and demographic data about the person. While this approach has been very successful, it has come at a high cost time-wise. Much like the role of an online course instructor, instructor (or in this case researcher) presence is essential. Replying to emails, updating webpages, posting on social media, and connecting with your volunteer data collectors can become a full time job - and that's even before you start the data analysis. We encourage future researchers to plan ahead for this when starting a crowd sourcing project involving the general public, and seek advice and training in social media, web site development and communication techniques like semi-automated email.

  13. iCrowd: agent-based behavior modeling and crowd simulator

    Science.gov (United States)

    Kountouriotis, Vassilios I.; Paterakis, Manolis; Thomopoulos, Stelios C. A.

    2016-05-01

    Initially designed in the context of the TASS (Total Airport Security System) FP-7 project, the Crowd Simulation platform developed by the Integrated Systems Lab of the Institute of Informatics and Telecommunications at N.C.S.R. Demokritos, has evolved into a complete domain-independent agent-based behavior simulator with an emphasis on crowd behavior and building evacuation simulation. Under continuous development, it reflects an effort to implement a modern, multithreaded, data-oriented simulation engine employing latest state-of-the-art programming technologies and paradigms. It is based on an extensible architecture that separates core services from the individual layers of agent behavior, offering a concrete simulation kernel designed for high-performance and stability. Its primary goal is to deliver an abstract platform to facilitate implementation of several Agent-Based Simulation solutions with applicability in several domains of knowledge, such as: (i) Crowd behavior simulation during [in/out] door evacuation. (ii) Non-Player Character AI for Game-oriented applications and Gamification activities. (iii) Vessel traffic modeling and simulation for Maritime Security and Surveillance applications. (iv) Urban and Highway Traffic and Transportation Simulations. (v) Social Behavior Simulation and Modeling.

  14. Analysis of genetic polymorphisms in skeletal Class I crowding.

    Science.gov (United States)

    Ting, Tung Yuen; Wong, Ricky Wing Kit; Rabie, A Bakr M

    2011-07-01

    Dental crowding is a problem for both adolescents and adults in modern society. The purpose of this research was to identify single nucleotide polymorphisms (SNPs) responsible for crowding in subjects with skeletal Class I relationships. The case subjects consisted of healthy Chinese people living in Hong Kong with skeletal Class I relationships and at least 5 mm of crowding in either arch. The control subjects met the same requirements but lacked crowding or spacing. SNP genotyping was performed on the MassARRAY platform. The chi-square test was used to compare genotype and allele type distributions between the case and the control groups. Logistic regression was used to calculate odds ratios with 95% confidence intervals, and the effects of age and sex for each SNP. Analyses of linkage disequilibrium and haplotype associations between SNPs were performed with software. Five SNPs were found to be significantly different in genotype or allele type distributions. SNP rs372024 was significantly associated with crowding (P = 0.004). Two SNPs, rs3764746 and rs3795170, on the EDA gene were found to be associated marginally. SNPs rs1005464 and rs15705 also exhibited marginal association with crowding. The effects of associated SNPs remained significant after adjustments for age and sex factors. This study suggests an association for the genes EDA and XEDAR in dental crowding in the Hong Kong Chinese population. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  15. Online anomaly detection in crowd scenes via structure analysis.

    Science.gov (United States)

    Yuan, Yuan; Fang, Jianwu; Wang, Qi

    2015-03-01

    Abnormal behavior detection in crowd scenes is continuously a challenge in the field of computer vision. For tackling this problem, this paper starts from a novel structure modeling of crowd behavior. We first propose an informative structural context descriptor (SCD) for describing the crowd individual, which originally introduces the potential energy function of particle's interforce in solid-state physics to intuitively conduct vision contextual cueing. For computing the crowd SCD variation effectively, we then design a robust multi-object tracker to associate the targets in different frames, which employs the incremental analytical ability of the 3-D discrete cosine transform (DCT). By online spatial-temporal analyzing the SCD variation of the crowd, the abnormality is finally localized. Our contribution mainly lies on three aspects: 1) the new exploration of abnormal detection from structure modeling where the motion difference between individuals is computed by a novel selective histogram of optical flow that makes the proposed method can deal with more kinds of anomalies; 2) the SCD description that can effectively represent the relationship among the individuals; and 3) the 3-D DCT multi-object tracker that can robustly associate the limited number of (instead of all) targets which makes the tracking analysis in high density crowd situation feasible. Experimental results on several publicly available crowd video datasets verify the effectiveness of the proposed method.

  16. Correlation Imaging Reveals Specific Crowding Dynamics of Kinesin Motor Proteins

    Science.gov (United States)

    Miedema, Daniël M.; Kushwaha, Vandana S.; Denisov, Dmitry V.; Acar, Seyda; Nienhuis, Bernard; Peterman, Erwin J. G.; Schall, Peter

    2017-10-01

    Molecular motor proteins fulfill the critical function of transporting organelles and other building blocks along the biopolymer network of the cell's cytoskeleton, but crowding effects are believed to crucially affect this motor-driven transport due to motor interactions. Physical transport models, like the paradigmatic, totally asymmetric simple exclusion process (TASEP), have been used to predict these crowding effects based on simple exclusion interactions, but verifying them in experiments remains challenging. Here, we introduce a correlation imaging technique to precisely measure the motor density, velocity, and run length along filaments under crowding conditions, enabling us to elucidate the physical nature of crowding and test TASEP model predictions. Using the kinesin motor proteins kinesin-1 and OSM-3, we identify crowding effects in qualitative agreement with TASEP predictions, and we achieve excellent quantitative agreement by extending the model with motor-specific interaction ranges and crowding-dependent detachment probabilities. These results confirm the applicability of basic nonequilibrium models to the intracellular transport and highlight motor-specific strategies to deal with crowding.

  17. Phosphoglycerate kinase in crowded and cellular environments

    Science.gov (United States)

    Ebbinghaus, Simon

    2011-03-01

    We developed the temperature-jump fluorescence microscope to spatio-temporally resolve fast biomolecular kinetics and stability inside a single mammalian cell. We measured the reversible fast folding kinetics as well as folding thermodynamics of a fluorescent phosphoglycerate kinase construct in a bone marrow cell with subcellular resolution. The same instrument was also used to perform the comparative in vitro measurement in dilute buffer and crowded environments. Investigating an ensemble of cells, each cell has its own unique kinetic signature that can differ substantially from the in vitro result. Variations in the cytoplasmic environment are significant modulators of the protein energy landscape. We quantitate these variations with a statistical analysis of multiple cells and compare folding dynamics on the nm length scale with μ m length scale diffusion processes. Cytoplasmic energy landscape modulation may be a candidate for non-genetic regulation of proteins but also challenges protein homeostasis.

  18. Crowd-Sourced Global Earthquake Early Warning

    Science.gov (United States)

    Minson, S. E.; Brooks, B. A.; Glennie, C. L.; Murray, J. R.; Langbein, J. O.; Owen, S. E.; Iannucci, B. A.; Hauser, D. L.

    2014-12-01

    Although earthquake early warning (EEW) has shown great promise for reducing loss of life and property, it has only been implemented in a few regions due, in part, to the prohibitive cost of building the required dense seismic and geodetic networks. However, many cars and consumer smartphones, tablets, laptops, and similar devices contain low-cost versions of the same sensors used for earthquake monitoring. If a workable EEW system could be implemented based on either crowd-sourced observations from consumer devices or very inexpensive networks of instruments built from consumer-quality sensors, EEW coverage could potentially be expanded worldwide. Controlled tests of several accelerometers and global navigation satellite system (GNSS) receivers typically found in consumer devices show that, while they are significantly noisier than scientific-grade instruments, they are still accurate enough to capture displacements from moderate and large magnitude earthquakes. The accuracy of these sensors varies greatly depending on the type of data collected. Raw coarse acquisition (C/A) code GPS data are relatively noisy. These observations have a surface displacement detection threshold approaching ~1 m and would thus only be useful in large Mw 8+ earthquakes. However, incorporating either satellite-based differential corrections or using a Kalman filter to combine the raw GNSS data with low-cost acceleration data (such as from a smartphone) decreases the noise dramatically. These approaches allow detection thresholds as low as 5 cm, potentially enabling accurate warnings for earthquakes as small as Mw 6.5. Simulated performance tests show that, with data contributed from only a very small fraction of the population, a crowd-sourced EEW system would be capable of warning San Francisco and San Jose of a Mw 7 rupture on California's Hayward fault and could have accurately issued both earthquake and tsunami warnings for the 2011 Mw 9 Tohoku-oki, Japan earthquake.

  19. Profile fitting in crowded astronomical images

    Science.gov (United States)

    Manish, Raja

    Around 18,000 known objects currently populate the near Earth space. These constitute active space assets as well as space debris objects. The tracking and cataloging of such objects relies on observations, most of which are ground based. Also, because of the great distance to the objects, only non-resolved object images can be obtained from the observations. Optical systems consist of telescope optics and a detector. Nowadays, usually CCD detectors are used. The information that is sought to be extracted from the frames are the individual object's astrometric position. In order to do so, the center of the object's image on the CCD frame has to be found. However, the observation frames that are read out of the detector are subject to noise. There are three different sources of noise: celestial background sources, the object signal itself and the sensor noise. The noise statistics are usually modeled as Gaussian or Poisson distributed or their combined distribution. In order to achieve a near real time processing, computationally fast and reliable methods for the so-called centroiding are desired; analytical methods are preferred over numerical ones of comparable accuracy. In this work, an analytic method for the centroiding is investigated and compared to numerical methods. Though the work focuses mainly on astronomical images, same principle could be applied on non-celestial images containing similar data. The method is based on minimizing weighted least squared (LS) error between observed data and the theoretical model of point sources in a novel yet simple way. Synthetic image frames have been simulated. The newly developed method is tested in both crowded and non-crowded fields where former needs additional image handling procedures to separate closely packed objects. Subsequent analysis on real celestial images corroborate the effectiveness of the approach.

  20. CrowdPhase: crowdsourcing the phase problem

    Energy Technology Data Exchange (ETDEWEB)

    Jorda, Julien; Sawaya, Michael R. [Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); Yeates, Todd O., E-mail: yeates@mbi.ucla.edu [Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); Molecular Biology Institute, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); University of California, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States)

    2014-06-01

    The idea of attacking the phase problem by crowdsourcing is introduced. Using an interactive, multi-player, web-based system, participants work simultaneously to select phase sets that correspond to better electron-density maps in order to solve low-resolution phasing problems. The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it

  1. Designing for crowd well-being : Current designs, strategies and future design suggestions

    NARCIS (Netherlands)

    Li, J.; de Ridder, H.; Vermeeren, A.P.O.S.; Conrado, C.; Martella, C.

    2013-01-01

    This paper introduces the concept of crowd well-being and the needs for sustaining it. Crowd well-being can be interpreted as crowd members’ evaluations on their emotional reactions, moods and judgments they form about their satisfactions, goals or needs fulfillment in a crowded situation according

  2. The wisdom of the crowd in funding: : Information heterogeneity and social networks of crowdfunder

    NARCIS (Netherlands)

    Polzin, F.H.J.; Toxopeus, H.S.; Stam, F.C.

    2016-01-01

    Crowdfunding has enabled large crowds to fund innovative projects. This type of funding might tap into the wisdom of crowds who were previously disconnected from the funding process. We distinguish between in-crowd and out-crowd funders (with and without ties to project creators) in order to test

  3. NECESSITY FACTORS AND PREDICTORS OF DENTAL CROWDING TREATMENT

    Directory of Open Access Journals (Sweden)

    Georgeta ZEGAN

    2015-09-01

    Full Text Available The aim of the study was to identify the significant necessity and predictive factors of dental crowding treatment, on 422 subjects (165 boys and 257 girls from the North-East part of Romania. Correlations have been established between dental crowding and age, dentition, Angle class of malocclusions, the etiological factors, types and modalities of treatments, and types of orthodontic appliances employed (p0.05. The necessity and predictive factors of the treatment were adequate with age, dentition, severity of crowding and Angle class of malocclusion.

  4. Estimating the number of people in crowded scenes

    Science.gov (United States)

    Kim, Minjin; Kim, Wonjun; Kim, Changick

    2011-01-01

    This paper presents a method to estimate the number of people in crowded scenes without using explicit object segmentation or tracking. The proposed method consists of three steps as follows: (1) extracting space-time interest points using eigenvalues of the local spatio-temporal gradient matrix, (2) generating crowd regions based on space-time interest points, and (3) estimating the crowd density based on the multiple regression. In experimental results, the efficiency and robustness of our proposed method are demonstrated by using PETS 2009 dataset.

  5. CROWDING AND SHOPPING VALUE IN LOW-INCOME RETAIL CENTERS

    Directory of Open Access Journals (Sweden)

    Izabelle Quezado

    2014-07-01

    Full Text Available Considering the great potential of low-income consumption, this research is based on the scales developed by Babin, Darden and Griffin (1994 and by Machleit, Kellaris and Eroglu (1994, aiming to investigate hedonic and utilitarian consumer behavior and its relation with low-income perception of crowding. A research was performed with 404 consumers in real store environment and the results showed that consumers revealed being prone to utilitarian behavior in both centers. About crowding phenomenon, the consumers felt more uncomfortable by crowding at the commercial center with less infrastructure. There were indices that this discomfort was less intense in hedonic consumers.

  6. The loss of short-term visual representations over time: decay or temporal distinctiveness?

    Science.gov (United States)

    Mercer, Tom

    2014-12-01

    There has been much recent interest in the loss of visual short-term memories over the passage of time. According to decay theory, visual representations are gradually forgotten as time passes, reflecting a slow and steady distortion of the memory trace. However, this is controversial and decay effects can be explained in other ways. The present experiment aimed to reexamine the maintenance and loss of visual information over the short term. Decay and temporal distinctiveness models were tested using a delayed discrimination task, in which participants compared complex and novel objects over unfilled retention intervals of variable length. Experiment 1 found no significant change in the accuracy of visual memory from 2 to 6 s, but the gap separating trials reliably influenced task performance. Experiment 2 found evidence for information loss at a 10-s retention interval, but temporally separating trials restored the fidelity of visual memory, possibly because temporally isolated representations are distinct from older memory traces. In conclusion, visual representations lose accuracy at some point after 6 s, but only within temporally crowded contexts. These findings highlight the importance of temporal distinctiveness within visual short-term memory. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  7. Structural-functional relationships between eye orbital imaging biomarkers and clinical visual assessments

    Science.gov (United States)

    Yao, Xiuya; Chaganti, Shikha; Nabar, Kunal P.; Nelson, Katrina; Plassard, Andrew; Harrigan, Rob L.; Mawn, Louise A.; Landman, Bennett A.

    2017-02-01

    Eye diseases and visual impairment affect millions of Americans and induce billions of dollars in annual economic burdens. Expounding upon existing knowledge of eye diseases could lead to improved treatment and disease prevention. This research investigated the relationship between structural metrics of the eye orbit and visual function measurements in a cohort of 470 patients from a retrospective study of ophthalmology records for patients (with thyroid eye disease, orbital inflammation, optic nerve edema, glaucoma, intrinsic optic nerve disease), clinical imaging, and visual function assessments. Orbital magnetic resonance imaging (MRI) and computed tomography (CT) images were retrieved and labeled in 3D using multi-atlas label fusion. Based on the 3D structures, both traditional radiology measures (e.g., Barrett index, volumetric crowding index, optic nerve length) and novel volumetric metrics were computed. Using stepwise regression, the associations between structural metrics and visual field scores (visual acuity, functional acuity, visual field, functional field, and functional vision) were assessed. Across all models, the explained variance was reasonable (R2 0.1-0.2) but highly significant (p < 0.001). Instead of analyzing a specific pathology, this study aimed to analyze data across a variety of pathologies. This approach yielded a general model for the connection between orbital structural imaging biomarkers and visual function.

  8. Mingo National Wildlife Refuge : Station Crowd Control Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Crowd Control Plan for Mingo NWR outlines operational procedures in the event of a civil disorder on the Refuge. An inventory of resources is provided, along...

  9. Detecting dominant motion patterns in crowds of pedestrians

    Science.gov (United States)

    Saqib, Muhammad; Khan, Sultan Daud; Blumenstein, Michael

    2017-02-01

    As the population of the world increases, urbanization generates crowding situations which poses challenges to public safety and security. Manual analysis of crowded situations is a tedious job and usually prone to errors. In this paper, we propose a novel technique of crowd analysis, the aim of which is to detect different dominant motion patterns in real-time videos. A motion field is generated by computing the dense optical flow. The motion field is then divided into blocks. For each block, we adopt an Intra-clustering algorithm for detecting different flows within the block. Later on, we employ Inter-clustering for clustering the flow vectors among different blocks. We evaluate the performance of our approach on different real-time videos. The experimental results show that our proposed method is capable of detecting distinct motion patterns in crowded videos. Moreover, our algorithm outperforms state-of-the-art methods.

  10. Diffusion in crowded biological environments: applications of Brownian dynamics

    Directory of Open Access Journals (Sweden)

    Długosz Maciej

    2011-03-01

    Full Text Available Abstract Biochemical reactions in living systems occur in complex, heterogeneous media with total concentrations of macromolecules in the range of 50 - 400 mgml. Molecular species occupy a significant fraction of the immersing medium, up to 40% of volume. Such complex and volume-occupied environments are generally termed 'crowded' and/or 'confined'. In crowded conditions non-specific interactions between macromolecules may hinder diffusion - a major process determining metabolism, transport, and signaling. Also, the crowded media can alter, both qualitatively and quantitatively, the reactions in vivo in comparison with their in vitro counterparts. This review focuses on recent developments in particle-based Brownian dynamics algorithms, their applications to model diffusive transport in crowded systems, and their abilities to reproduce and predict the behavior of macromolecules under in vivo conditions.

  11. State Variability in Childrens Medicaid Crowd-Out Estimates

    Data.gov (United States)

    U.S. Department of Health & Human Services — Health insurance crowd-out occurs when individuals enrolled in a public health insurance plan would have enrolled in a private plan but for the public option. The...

  12. Designing interactive technology for crowd experiences - beyond sanitization

    DEFF Research Database (Denmark)

    Veerasawmy, Rune

    2014-01-01

    in a conceptual model of social experiences that presents crowd experiences as a distinct type of social experience. This is different from what previously have been explored within experi- ence-oriented design. This dissertation is composed of four research papers framed by an overview that summarizes...... experience within interaction design. This dissertation introduces an understanding of crowd experience as a distinct type of social experiences driven by non-rational behavior. This conceptual understanding is established in the intersection between sociological crowd theory and a pragmatist perspective...... within experience-oriented design that provides designers and researchers with an awareness and vocabulary of crowds’ distinct sociality, when designing inter- active technology for crowd experiences. The second contribution of the dissertation is a perspective on spectator experiences that goes beyond...

  13. Emergency room crowding: a marker of hospital health.

    Science.gov (United States)

    Barish, Robert A; McGauly, Patrick L; Arnold, Thomas C

    2012-01-01

    Emergency room (ER) crowding has become a widespread problem in hospitals across the United States. Two main reasons can be cited. First, emergency medicine is the only specialty in the "House of Medicine" that has a federal mandate to provide care to any patients requesting treatment. Second, primary care providers are in short supply, forcing sick people to seek medical care in ERs. Once seen as an "ER problem," crowding has become more appropriately recognized as a "hospital problem," related to factors beyond the doors of the ER. This realization has led many regulating agencies to launch corrective attempts, some of which have actually been effective. Now, the lack of ER crowding is considered a measure of the success of a hospital or system. This review considers the complex causative factors that contribute to ER crowding and explores corrective measures that may prove helpful in alleviating this paralyzing condition.

  14. Household crowding and psychosocial health among Inuit in Greenland

    DEFF Research Database (Denmark)

    Riva, Mylène; Larsen, Christina Viskum Lytken; Bjerregaard, Peter

    2014-01-01

    OBJECTIVES: Poor housing conditions experienced by many Indigenous peoples threaten their health and well-being. This study examines whether household crowding is associated with poorer psychosocial health among Greenlanders, and the mediating role of social support. It also assesses whether Inuit...... men and women are differently influenced by their housing conditions. METHODS: Data on more than 3,000 Inuit aged 18 years and older are from the Inuit health in transition Greenland survey. Associations between household crowding and composition, and mental well-being and binge drinking were examined....... The association between household crowding and mental well-being was significantly mediated by social support. This suggests that having a strong social network may buffer the deleterious impacts of household crowding. CONCLUSIONS: Targeting housing conditions and fostering social support as part of population...

  15. The effect of music tempo on perceived crowding in retailing

    OpenAIRE

    Fiksdal, Taisiya; Hua, Wen

    2016-01-01

    In the marketing field the influence of in-store atmospherics on consumers’ shopping behavior is widely accepted. We seek to understand the effects of instore music tempo on perceived crowding and how music tempo can affect emotions, arousal and perceived control occurring in retail stores. Hence, our research questions are the following: Does music tempo influence the perceived crowding? Do arousal, perceived control, positive and negative emotions, mediate the relationship...

  16. Emergency department throughput, crowding, and financial outcomes for hospitals.

    Science.gov (United States)

    Handel, Daniel A; Hilton, Joshua A; Ward, Michael J; Rabin, Elaine; Zwemer, Frank L; Pines, Jesse M

    2010-08-01

    Emergency department (ED) crowding has been identified as a major public health problem in the United States by the Institute of Medicine. ED crowding not only is associated with poorer patient outcomes, but it also contributes to lost demand for ED services when patients leave without being seen and hospitals must go on ambulance diversion. However, somewhat paradoxically, ED crowding may financially benefit hospitals. This is because ED crowding allows hospitals to maximize occupancy with well-insured, elective patients while patients wait in the ED. In this article, the authors propose a more holistic model of hospital flow and revenue that contradicts this notion and offer suggestions for improvements in ED and hospital management that may not only reduce crowding and improve quality, but also increase hospital revenues. Also proposed is that increased efficiency and quality in U.S. hospitals will require changes in systematic microeconomic and macroeconomic incentives that drive the delivery of health services in the United States. Finally, the authors address several questions to propose mutually beneficial solutions to ED crowding that include the realignment of hospital incentives, changing culture to promote flow, and several ED-based strategies to improve ED efficiency.

  17. What Macromolecular Crowding Can Do to a Protein

    Science.gov (United States)

    Kuznetsova, Irina M.; Turoverov, Konstantin K.; Uversky, Vladimir N.

    2014-01-01

    The intracellular environment represents an extremely crowded milieu, with a limited amount of free water and an almost complete lack of unoccupied space. Obviously, slightly salted aqueous solutions containing low concentrations of a biomolecule of interest are too simplistic to mimic the “real life” situation, where the biomolecule of interest scrambles and wades through the tightly packed crowd. In laboratory practice, such macromolecular crowding is typically mimicked by concentrated solutions of various polymers that serve as model “crowding agents”. Studies under these conditions revealed that macromolecular crowding might affect protein structure, folding, shape, conformational stability, binding of small molecules, enzymatic activity, protein-protein interactions, protein-nucleic acid interactions, and pathological aggregation. The goal of this review is to systematically analyze currently available experimental data on the variety of effects of macromolecular crowding on a protein molecule. The review covers more than 320 papers and therefore represents one of the most comprehensive compendia of the current knowledge in this exciting area. PMID:25514413

  18. How social influence can undermine the wisdom of crowd effect.

    Science.gov (United States)

    Lorenz, Jan; Rauhut, Heiko; Schweitzer, Frank; Helbing, Dirk

    2011-05-31

    Social groups can be remarkably smart and knowledgeable when their averaged judgements are compared with the judgements of individuals. Already Galton [Galton F (1907) Nature 75:7] found evidence that the median estimate of a group can be more accurate than estimates of experts. This wisdom of crowd effect was recently supported by examples from stock markets, political elections, and quiz shows [Surowiecki J (2004) The Wisdom of Crowds]. In contrast, we demonstrate by experimental evidence (N = 144) that even mild social influence can undermine the wisdom of crowd effect in simple estimation tasks. In the experiment, subjects could reconsider their response to factual questions after having received average or full information of the responses of other subjects. We compare subjects' convergence of estimates and improvements in accuracy over five consecutive estimation periods with a control condition, in which no information about others' responses was provided. Although groups are initially "wise," knowledge about estimates of others narrows the diversity of opinions to such an extent that it undermines the wisdom of crowd effect in three different ways. The "social influence effect" diminishes the diversity of the crowd without improvements of its collective error. The "range reduction effect" moves the position of the truth to peripheral regions of the range of estimates so that the crowd becomes less reliable in providing expertise for external observers. The "confidence effect" boosts individuals' confidence after convergence of their estimates despite lack of improved accuracy. Examples of the revealed mechanism range from misled elites to the recent global financial crisis.

  19. Devaluation, crowding or skill specificity? Exploring the mechanisms behind the lower wages in female professions.

    Science.gov (United States)

    Grönlund, Anne; Magnusson, Charlotta

    2013-07-01

    A conspicuous finding in research on the gender wage gap is that wages are related to the percentage females in an occupation (percent F). Three mechanisms have been suggested to explain this relationship: a devaluation of women's work, a crowding of women into a limited number of occupations, and a female disadvantage in the accumulation of specific human capital. In this analysis, based on data from the Swedish Level of Living Survey of 2000 (n=2915), we distinguish between these mechanisms using measures of devaluation (Treiman's prestige scale), crowding (employee dependence on current employer) and specific human capital (on-the-job training). The results show that all the indicators are related to percent F, but not in a linear fashion, and that the percent F-effect on wages is overstated and misspecified. Female-dominated occupations stand out with lower wages than both male-dominated and gender-integrated occupations and this is not explained by any of our measures. Thus, if the hypotheses on segregation and wages should be sustained, they must be further specified and new measures must be found to prove their worth. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Nudging Cooperation in a Crowd Experiment

    Science.gov (United States)

    Niella, Tamara; Stier-Moses, Nicolás; Sigman, Mariano

    2016-01-01

    We examine the hypothesis that driven by a competition heuristic, people don't even reflect or consider whether a cooperation strategy may be better. As a paradigmatic example of this behavior we propose the zero-sum game fallacy, according to which people believe that resources are fixed even when they are not. We demonstrate that people only cooperate if the competitive heuristic is explicitly overridden in an experiment in which participants play two rounds of a game in which competition is suboptimal. The observed spontaneous behavior for most players was to compete. Then participants were explicitly reminded that the competing strategy may not be optimal. This minor intervention boosted cooperation, implying that competition does not result from lack of trust or willingness to cooperate but instead from the inability to inhibit the competition bias. This activity was performed in a controlled laboratory setting and also as a crowd experiment. Understanding the psychological underpinnings of these behaviors may help us improve cooperation and thus may have vast practical consequences to our society. PMID:26797425

  1. Crowd-Sourced Intelligence Agency: Prototyping counterveillance

    Directory of Open Access Journals (Sweden)

    Jennifer Gradecki

    2017-02-01

    Full Text Available This paper discusses how an interactive artwork, the Crowd-Sourced Intelligence Agency (CSIA, can contribute to discussions of Big Data intelligence analytics. The CSIA is a publicly accessible Open Source Intelligence (OSINT system that was constructed using information gathered from technical manuals, research reports, academic papers, leaked documents, and Freedom of Information Act files. Using a visceral heuristic, the CSIA demonstrates how the statistical correlations made by automated classification systems are different from human judgment and can produce false-positives, as well as how the display of information through an interface can affect the judgment of an intelligence agent. The public has the right to ask questions about how a computer program determines if they are a threat to national security and to question the practicality of using statistical pattern recognition algorithms in place of human judgment. Currently, the public’s lack of access to both Big Data and the actual datasets intelligence agencies use to train their classification algorithms keeps the possibility of performing effective sous-dataveillance out of reach. Without this data, the results returned by the CSIA will not be identical to those of intelligence agencies. Because we have replicated how OSINT is processed, however, our results will resemble the type of results and mistakes made by OSINT systems. The CSIA takes some initial steps toward contributing to an informed public debate about large-scale monitoring of open source, social media data and provides a prototype for counterveillance and sousveillance tools for citizens.

  2. Library enhancement through the wisdom of crowds.

    Science.gov (United States)

    Hack, Michael D; Rassokhin, Dmitrii N; Buyck, Christophe; Seierstad, Mark; Skalkin, Andrew; ten Holte, Peter; Jones, Todd K; Mirzadegan, Taraneh; Agrafiotis, Dimitris K

    2011-12-27

    We present a novel approach for enhancing the diversity of a chemical library rooted on the theory of the wisdom of crowds. Our approach was motivated by a desire to tap into the collective experience of our global medicinal chemistry community and involved four basic steps: (1) Candidate compounds for acquisition were screened using various structural and property filters in order to eliminate clearly nondrug-like matter. (2) The remaining compounds were clustered together with our in-house collection using a novel fingerprint-based clustering algorithm that emphasizes common substructures and works with millions of molecules. (3) Clusters populated exclusively by external compounds were identified as "diversity holes," and representative members of these clusters were presented to our global medicinal chemistry community, who were asked to specify which ones they liked, disliked, or were indifferent to using a simple point-and-click interface. (4) The resulting votes were used to rank the clusters from most to least desirable, and to prioritize which ones should be targeted for acquisition. Analysis of the voting results reveals interesting voter behaviors and distinct preferences for certain molecular property ranges that are fully consistent with lead-like profiles established through systematic analysis of large historical databases.

  3. Plagiarism explainer for students

    OpenAIRE

    Barba, Lorena A.

    2016-01-01

    A slide deck to serve as an explainer of plagiarism in academic settings, with a personal viewpoint. For my students.Also on SpeakerDeck:https://speakerdeck.com/labarba/plagiarism-explainer-for-students(The slide viewer on SpeakerDeck is much nicer.)

  4. Discrete element crowd model for pedestrian evacuation through an exit

    Science.gov (United States)

    Peng, Lin; Jian, Ma; Siuming, Lo

    2016-03-01

    A series of accidents caused by crowds within the last decades evoked a lot of scientific interest in modeling the movement of pedestrian crowds. Based on the discrete element method, a granular dynamic model, in which the human body is simplified as a self-driven sphere, is proposed to simulate the characteristics of crowd flow through an exit. In this model, the repulsive force among people is considered to have an anisotropic feature, and the physical contact force due to body deformation is quantified by the Hertz contact model. The movement of the human body is simulated by applying the second Newton’s law. The crowd flow through an exit at different desired velocities is studied and simulation results indicated that crowd flow exhibits three distinct states, i.e., smooth state, transition state and phase separation state. In the simulation, the clogging phenomenon occurs more easily when the desired velocity is high and the exit may as a result be totally blocked at a desired velocity of 1.6 m/s or above, leading to faster-to-frozen effect. Project supported by the National Natural Science Foundation of China (Grant Nos. 71473207, 51178445, and 71103148), the Research Grant Council, Government of Hong Kong, China (Grant No. CityU119011), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 2682014CX103 and 2682014RC05).

  5. Is Malnutrition Associated with Crowding in Permanent Dentition?

    Directory of Open Access Journals (Sweden)

    Erika B. A. F. Thomaz

    2010-09-01

    Full Text Available Evidence suggests that energy-protein malnutrition is associated with impaired growth and development of facial bones. The objective of this study was to investigate the association between nutritional status and reduced space for dental eruption (crowding in permanent dentition. A cross-sectional study with probabilistic sampling design was used. We evaluated 2,060 students aged 12 to 15 years enrolled in schools in the northeast of Brazil. Crowding was defined according to World Health Organization (WHO as misalignment of teeth due to lack of space for them to erupt in the correct position. Nutritional status was evaluated by means of body mass index and height-for-age, using the WHO’s reference curves. Parents and adolescents responded to a questionnaire about demographic, socioeconomic, biological and behavioral characteristics. The associations were estimated by odds ratio (OR in multivariate logistic regression analysis (alpha = 0.05. Confounding and effect-modification were taken into account. An association between low height-for-age (z-score < –1SD and crowding was only observed in adolescents with a prolonged history of mouth breathing (OR = 3.1. No association was observed between underweight and crowding. Malnutrition is related to crowding in permanent dentition among mouth-breathing adolescents. Policy actions aimed at reducing low height-for-age and unhealthy oral habits are strongly recommended. However, further studies are needed to increase the consistency of these findings and improve understanding of the subject.

  6. Social identification moderates the effect of crowd density on safety at the Hajj.

    Science.gov (United States)

    Alnabulsi, Hani; Drury, John

    2014-06-24

    Crowd safety is a major concern for those attending and managing mass gatherings, such as the annual Hajj or pilgrimage to Mecca (also called Makkah). One threat to crowd safety at such events is crowd density. However, recent research also suggests that psychological membership of crowds can have positive benefits. We tested the hypothesis that the effect of density on safety might vary depending on whether there is shared social identification in the crowd. We surveyed 1,194 pilgrims at the Holy Mosque, Mecca, during the 2012 Hajj. Analysis of the data showed that the negative effect of crowd density on reported safety was moderated by social identification with the crowd. Whereas low identifiers reported reduced safety with greater crowd density, high identifiers reported increased safety with greater crowd density. Mediation analysis suggested that a reason for these moderation effects was the perception that other crowd members were supportive. Differences in reported safety across national groups (Arab countries and Iran compared with the rest) were also explicable in terms of crowd identification and perceived support. These findings support a social identity account of crowd behavior and offer a novel perspective on crowd safety management.

  7. Social identification moderates the effect of crowd density on safety at the Hajj

    Science.gov (United States)

    Alnabulsi, Hani; Drury, John

    2014-01-01

    Crowd safety is a major concern for those attending and managing mass gatherings, such as the annual Hajj or pilgrimage to Mecca (also called Makkah). One threat to crowd safety at such events is crowd density. However, recent research also suggests that psychological membership of crowds can have positive benefits. We tested the hypothesis that the effect of density on safety might vary depending on whether there is shared social identification in the crowd. We surveyed 1,194 pilgrims at the Holy Mosque, Mecca, during the 2012 Hajj. Analysis of the data showed that the negative effect of crowd density on reported safety was moderated by social identification with the crowd. Whereas low identifiers reported reduced safety with greater crowd density, high identifiers reported increased safety with greater crowd density. Mediation analysis suggested that a reason for these moderation effects was the perception that other crowd members were supportive. Differences in reported safety across national groups (Arab countries and Iran compared with the rest) were also explicable in terms of crowd identification and perceived support. These findings support a social identity account of crowd behavior and offer a novel perspective on crowd safety management. PMID:24927593

  8. Visual Confidence.

    Science.gov (United States)

    Mamassian, Pascal

    2016-10-14

    Visual confidence refers to an observer's ability to judge the accuracy of her perceptual decisions. Even though confidence judgments have been recorded since the early days of psychophysics, only recently have they been recognized as essential for a deeper understanding of visual perception. The reluctance to study visual confidence may have come in part from obtaining convincing experimental evidence in favor of metacognitive abilities rather than just perceptual sensitivity. Some effort has thus been dedicated to offer different experimental paradigms to study visual confidence in humans and nonhuman animals. To understand the origins of confidence judgments, investigators have developed two competing frameworks. The approach based on signal decision theory is popular but fails to account for response times. In contrast, the approach based on accumulation of evidence models naturally includes the dynamics of perceptual decisions. These models can explain a range of results, including the apparently paradoxical dissociation between performance and confidence that is sometimes observed.

  9. Macromolecular crowding: chemistry and physics meet biology (Ascona, Switzerland, 10-14 June 2012)

    Science.gov (United States)

    Foffi, G.; Pastore, A.; Piazza, F.; Temussi, P. A.

    2013-08-01

    Princeton University (USA), drew attention to very important objects, namely Ribonucleoprotein (RNP) bodies. These are non-membrane-bound macromolecular assemblies that form from the dynamic interactions of RNA and proteins. The assembly of RNP bodies may sensitively depend on the biophysical features of the surrounding cytoplasm, including the degree of crowding, transport coefficients and mechanical properties. This dependency may have important implications for the RNA processing reactions involved in fundamental biological processes such as developmental cell growth. Remarkably, Brangwynne showed how RNPs behave in the cell as liquid droplets, pointing to a possible entirely new means that the cell could use to control and fine-tune its internal processes, in fact, more than that, a completely unexplored, new state of organization of living matter, and a functional one. Giuseppe Zaccai, from Institut Laue Langevin, Grenoble (France), showed that protein dynamics is more sensitive than structure to environmental factors such as crowding, solvent, temperature or pressure. Furthermore, he convincingly explained how neutron scattering provides unique experimental data to underpin MD calculations in this context. Following up on environment-induced modulations of protein functional dynamics, Ruth Nussinov, from Tel Aviv University (Israel), addressed the important problem of whether cellular signals can travel long distances in a crowded environment. She proposed a model based on the evolution of at least three properties: a modular functional organization of the cellular network, sequences in some key regions of proteins, such as linkers or loops, and compact interactions between proteins, possibly favoured by a crowded environment. The workshop ended on a keynote lecture by Jean-Marie Lehn, from the Université de Strasbourg (France). Lehn, 1987 Nobel Laureate in chemistry, offered a 'supramolecular view' of the field of molecular interactions. Supramolecular chemistry

  10. Bicyclists’ preferences for route characteristics and crowding in Copenhagen

    DEFF Research Database (Denmark)

    Vedel, Suzanne Elizabeth; Jacobsen, Jette Bredahl; Skov-Petersen, Hans

    2017-01-01

    Cycling as a mode of transportation is increasingly being advocated due to the many positive effects it has on people's health, the environment and to counteract increasing congestion on the transportation infrastructure. There is a long tradition of using cycling as a mode of transportation among....... The investigated attributes are cycle track, crowding, stops, environment/road type, green surroundings, and travel distance which is used as a payment vehicle to gain more desirable route characteristics. On average people state that they are willing to cycle 1.84 km longer if the route has a designated cycle...... track, and 0.8 km more if there are green surroundings too. Stops and crowding, based on number of cyclists on the route, have significant negative impacts on people's utility of a given route. People were willing to cycle one kilometre longer to avoid high levels of crowding and approximately 1.3 km...

  11. Jammed Humans in High-Density Crowd Disasters

    Science.gov (United States)

    Bottinelli, Arianna; Sumpter, David; Silverberg, Jesse

    When people gather in large groups like those found at Black Friday sales events, pilgrimages, heavy metal concerts, and parades, crowd density often becomes exceptionally high. As a consequence, these events can produce tragic outcomes such as stampedes and ''crowd crushes''. While human collective motion has been studied with active particle simulations, the underlying mechanisms for emergent behavior are less well understood. Here, we use techniques developed to study jammed granular materials to analyze an active matter model inspired by large groups of people gathering at a point of common interest. In the model, a single behavioral rule combined with body-contact interactions are sufficient for the emergence of a self-confined steady state, where particles fluctuate around a stable position. Applying mode analysis to this system, we find evidence for Goldstone modes, soft spots, and stochastic resonance, which may be the preferential mechanisms for dangerous emergent collective motions in crowds.

  12. Motivating crowding theory - opening the black box of intrinsic motivation

    DEFF Research Database (Denmark)

    Jacobsen, Christian Bøtcher

    2010-01-01

    employees. Motivation crowding theory claims that this may be at the expense of intrinsic motivation, if the extrinsic motivation factor is perceived to be controlling. On the other hand, intrinsic motivation will be enhanced (crowded in), if the extrinsic motivation factor is perceived to be supportive......Public employees work for many other reasons than because they are paid for it. In other words, intrinsic motivation is an important determinant for their performance. Nonetheless, public sector organizations increasingly rely on extrinsic motivation factors such as monetary incentives to motivate....... Studies have found support for the motivation crowding claim, but have neglected intrinsic motivation. This study opens the black box of intrinsic motivation and finds a meaningful distinction between task motivation and public service motivation. Among 2,772 physiotherapists in the Danish public sector...

  13. Cloud-based crowd sensing: a framework for location-based crowd analyzer and advisor

    Science.gov (United States)

    Aishwarya, K. C.; Nambi, A.; Hudson, S.; Nadesh, R. K.

    2017-11-01

    Cloud computing is an emerging field of computer science to integrate and explore large and powerful computing systems and storages for personal and also for enterprise requirements. Mobile Cloud Computing is the inheritance of this concept towards mobile hand-held devices. Crowdsensing, or to be precise, Mobile Crowdsensing is the process of sharing resources from an available group of mobile handheld devices that support sharing of different resources such as data, memory and bandwidth to perform a single task for collective reasons. In this paper, we propose a framework to use Crowdsensing and perform a crowd analyzer and advisor whether the user can go to the place or not. This is an ongoing research and is a new concept to which the direction of cloud computing has shifted and is viable for more expansion in the near future.

  14. How social influence can undermine the wisdom of crowd effect

    Science.gov (United States)

    Lorenz, Jan; Rauhut, Heiko; Schweitzer, Frank; Helbing, Dirk

    2011-01-01

    Social groups can be remarkably smart and knowledgeable when their averaged judgements are compared with the judgements of individuals. Already Galton [Galton F (1907) Nature 75:7] found evidence that the median estimate of a group can be more accurate than estimates of experts. This wisdom of crowd effect was recently supported by examples from stock markets, political elections, and quiz shows [Surowiecki J (2004) The Wisdom of Crowds]. In contrast, we demonstrate by experimental evidence (N = 144) that even mild social influence can undermine the wisdom of crowd effect in simple estimation tasks. In the experiment, subjects could reconsider their response to factual questions after having received average or full information of the responses of other subjects. We compare subjects’ convergence of estimates and improvements in accuracy over five consecutive estimation periods with a control condition, in which no information about others’ responses was provided. Although groups are initially “wise,” knowledge about estimates of others narrows the diversity of opinions to such an extent that it undermines the wisdom of crowd effect in three different ways. The “social influence effect” diminishes the diversity of the crowd without improvements of its collective error. The “range reduction effect” moves the position of the truth to peripheral regions of the range of estimates so that the crowd becomes less reliable in providing expertise for external observers. The “confidence effect” boosts individuals’ confidence after convergence of their estimates despite lack of improved accuracy. Examples of the revealed mechanism range from misled elites to the recent global financial crisis. PMID:21576485

  15. Contemporary understanding of riots: Classical crowd psychology, ideology and the social identity approach.

    Science.gov (United States)

    Stott, Clifford; Drury, John

    2016-04-01

    This article explores the origins and ideology of classical crowd psychology, a body of theory reflected in contemporary popularised understandings such as of the 2011 English 'riots'. This article argues that during the nineteenth century, the crowd came to symbolise a fear of 'mass society' and that 'classical' crowd psychology was a product of these fears. Classical crowd psychology pathologised, reified and decontextualised the crowd, offering the ruling elites a perceived opportunity to control it. We contend that classical theory misrepresents crowd psychology and survives in contemporary understanding because it is ideological. We conclude by discussing how classical theory has been supplanted in academic contexts by an identity-based crowd psychology that restores the meaning to crowd action, replaces it in its social context and in so doing transforms theoretical understanding of 'riots' and the nature of the self. © The Author(s) 2016.

  16. Contextual interactions in grating plaid configurations are explained by natural image statistics and neural modeling

    Directory of Open Access Journals (Sweden)

    Udo Alexander Ernst

    2016-10-01

    Full Text Available Processing natural scenes requires the visual system to integrate local features into global object descriptions. To achieve coherent representations, the human brain uses statistical dependencies to guide weighting of local feature conjunctions. Pairwise interactions among feature detectors in early visual areas may form the early substrate of these local feature bindings. To investigate local interaction structures in visual cortex, we combined psychophysical experiments with computational modeling and natural scene analysis. We first measured contrast thresholds for 2x2 grating patch arrangements (plaids, which differed in spatial frequency composition (low, high or mixed, number of grating patch co-alignments (0, 1 or 2, and inter-patch distances (1° and 2° of visual angle. Contrast thresholds for the different configurations were compared to the prediction of probability summation (PS among detector families tuned to the four retinal positions. For 1° distance the thresholds for all configurations were larger than predicted by PS, indicating inhibitory interactions. For 2° distance, thresholds were significantly lower compared to PS when the plaids were homogeneous in spatial frequency and orientation, but not when spatial frequencies were mixed or there was at least one misalignment. Next, we constructed a neural population model with horizontal laminar structure, which reproduced the detection thresholds after adaptation of connection weights. Consistent with prior work, contextual interactions were medium-range inhibition and long-range, orientation-specific excitation. However, inclusion of orientation-specific, inhibitory interactions between populations with different spatial frequency preferences were crucial for explaining detection thresholds. Finally, for all plaid configurations we computed their likelihood of occurrence in natural images. The likelihoods turned out to be inversely related to the detection thresholds obtained

  17. Reporting explained variance

    Science.gov (United States)

    Good, Ron; Fletcher, Harold J.

    The importance of reporting explained variance (sometimes referred to as magnitude of effects) in ANOVA designs is discussed in this paper. Explained variance is an estimate of the strength of the relationship between treatment (or other factors such as sex, grade level, etc.) and dependent variables of interest to the researcher(s). Three methods that can be used to obtain estimates of explained variance in ANOVA designs are described and applied to 16 studies that were reported in recent volumes of this journal. The results show that, while in most studies the treatment accounts for a relatively small proportion of the variance in dependent variable scores., in., some studies the magnitude of the treatment effect is respectable. The authors recommend that researchers in science education report explained variance in addition to the commonly reported tests of significance, since the latter are inadequate as the sole basis for making decisions about the practical importance of factors of interest to science education researchers.

  18. A compressed sensing model of crowding in peripheral vision

    Science.gov (United States)

    Hocke, Jens; Dorr, Michael; Barth, Erhardt

    2012-03-01

    We here model peripheral vision in a compressed sensing framework as a strategy of optimally guessing what stimulus corresponds to a sparsely encoded peripheral representation, and find that typical letter-crowding effects naturally arise from this strategy. The model is simple as it consists of only two convergence stages. We apply the model to the problem of crowding effects in reading. First, we show a few instructive examples of letter images that were reconstructed from encodings with different convergence rates. Then, we present an initial analysis of how the choice of model parameters affects the distortion of isolated and flanked letters.

  19. Non-extraction treatment of severe crowding with pendulum appliance

    Directory of Open Access Journals (Sweden)

    Chandrasekhar Gandikota

    2013-01-01

    Full Text Available An extraction case was planned for non-extraction treatment using pendulum appliance and the effect of appliance was evaluated in a 14-year-old girl with a severe maxillary and mandibular crowding followed by non-extraction fixed appliance preadjusted edgewise appliance mechanotherapy. Total treatment time was for 22 months. The obtuse nasolabial angle was maintained intact. Correction of crowding, co-ordinated arch forms was achieved with molar distalization. The impetus on soft-tissue paradigm is stressed in this case report and pendulum appliance can indeed boost our clinical acumen and swing our priorities toward non-extraction treatment.

  20. Non-extraction treatment of severe crowding with pendulum appliance.

    Science.gov (United States)

    Gandikota, Chandrasekhar; Venkata, Yudhister Palla; Challa, Padmalatha; Juvvadi, Shubhaker Rao

    2013-07-01

    An extraction case was planned for non-extraction treatment using pendulum appliance and the effect of appliance was evaluated in a 14-year-old girl with a severe maxillary and mandibular crowding followed by non-extraction fixed appliance preadjusted edgewise appliance mechanotherapy. Total treatment time was for 22 months. The obtuse nasolabial angle was maintained intact. Correction of crowding, co-ordinated arch forms was achieved with molar distalization. The impetus on soft-tissue paradigm is stressed in this case report and pendulum appliance can indeed boost our clinical acumen and swing our priorities toward non-extraction treatment.

  1. Lateral Vibrations of a Cable-Stayed Bridge under Crowd Excitation

    Directory of Open Access Journals (Sweden)

    Lijun Ouyang

    2015-01-01

    Full Text Available A cable-stayed bridge model under crowd excitation is established in this paper by considering the geometric nonlinear property of the cables. Lateral vibrations of the model are investigated by employing the center manifold theory, and the first-order approximation solution of the periodic vibration of the bridge is derived by using the energy method. Numerical simulations are carried out to verify the validity of our analytical expressions. Our research shows that the existence of the cables can reduce the amplitude and frequency of the bridge, especially for the large amplitude case. This might explain why measured data of a cable-stayed bridge (T-bridge in Japan vibrating under crowd excitation are much less than the theoretical results reported in previous studies in which the cable-stayed bridge is viewed as a single-degree-of-freedom system. Our analysis results suggest that the structure types of footbridges should not be easily ignored in the study of pedestrian-footbridge interaction.

  2. Organizing for a Peaceful Crowd: An Example of a Football Match

    Directory of Open Access Journals (Sweden)

    Ingrid Hylander

    2010-03-01

    Full Text Available Crowd violence has interested researchers in social psychology for many years and is an important issue for sports psychology (STOTT, ADANG, LIVINGSTONE & SCHREIBER, 2007; STOTT, HUTCHINSON & DRURY, 2001; RUSSELL, 2004; MUSTONEN, ARMS & RUSSELL, 1996. Riots in crowds have been explained from different theoretical perspectives (HYLANDER, 2008, such as individual differences, de-individuation (PRENTICE-DUNN & ROGERS, 1989, group interaction (DRURY & REICHER, 2000, history (GUTTMAN, 1986, 1998 and cultural perspectives (CRABBE, 2003. In this study, a social psychology model focusing on group interaction, the Aggravation and Mitigation (AM model (GUVÅ & HYLANDER, 2008; GRANSTRÖM, 2008; GRANSTRÖM & ROSANDER, 2008, is used as a means of analysis. This article applies the AM model to a sporting event to identify if and how peacemaking processes can be detected. Furthermore, the intention is to discern and illuminate organizational strategies that maybe linked to peacemaking processes. The main results indicate that when arrangements are based on (a "festival-making," (b arrangements for basic needs and recognizable order and (c the creation of a superordinate identity, then the outcome of mass events may turn out peaceful, which is also in line with the AM model. URN: urn:nbn:de:0114-fqs100283

  3. Randomness and the Madness of Crowds

    NARCIS (Netherlands)

    Weitzel, Utz|info:eu-repo/dai/nl/276323394; Rosenkranz, Stephanie|info:eu-repo/dai/nl/157222241

    2016-01-01

    Human interaction often appears to be random and at times even chaotic. We use game theory, the mathematical study of interactive decision making, to explain the role of rationality and randomness in strategic behavior. In many of these situations, humans deliberately create randomness as a best

  4. Effects of Crowding and Attention on High-Levels of Motion Processing and Motion Adaptation

    Science.gov (United States)

    Pavan, Andrea; Greenlee, Mark W.

    2015-01-01

    The motion after-effect (MAE) persists in crowding conditions, i.e., when the adaptation direction cannot be reliably perceived. The MAE originating from complex moving patterns spreads into non-adapted sectors of a multi-sector adapting display (i.e., phantom MAE). In the present study we used global rotating patterns to measure the strength of the conventional and phantom MAEs in crowded and non-crowded conditions, and when attention was directed to the adapting stimulus and when it was diverted away from the adapting stimulus. The results show that: (i) the phantom MAE is weaker than the conventional MAE, for both non-crowded and crowded conditions, and when attention was focused on the adapting stimulus and when it was diverted from it, (ii) conventional and phantom MAEs in the crowded condition are weaker than in the non-crowded condition. Analysis conducted to assess the effect of crowding on high-level of motion adaptation suggests that crowding is likely to affect the awareness of the adapting stimulus rather than degrading its sensory representation, (iii) for high-level of motion processing the attentional manipulation does not affect the strength of either conventional or phantom MAEs, neither in the non-crowded nor in the crowded conditions. These results suggest that high-level MAEs do not depend on attention and that at high-level of motion adaptation the effects of crowding are not modulated by attention. PMID:25615577

  5. A hybrid approach to crowd density estimation using statistical leaning and texture classification

    Science.gov (United States)

    Li, Yin; Zhou, Bowen

    2013-12-01

    Crowd density estimation is a hot topic in computer vision community. Established algorithms for crowd density estimation mainly focus on moving crowds, employing background modeling to obtain crowd blobs. However, people's motion is not obvious in most occasions such as the waiting hall in the airport or the lobby in the railway station. Moreover, conventional algorithms for crowd density estimation cannot yield desirable results for all levels of crowding due to occlusion and clutter. We propose a hybrid method to address the aforementioned problems. First, statistical learning is introduced for background subtraction, which comprises a training phase and a test phase. The crowd images are grided into small blocks which denote foreground or background. Then HOG features are extracted and are fed into a binary SVM for each block. Hence, crowd blobs can be obtained by the classification results of the trained classifier. Second, the crowd images are treated as texture images. Therefore, the estimation problem can be formulated as texture classification. The density level can be derived according to the classification results. We validate the proposed algorithm on some real scenarios where the crowd motion is not so obvious. Experimental results demonstrate that our approach can obtain the foreground crowd blobs accurately and work well for different levels of crowding.

  6. Emerging Adults' Self-Identified Peer Crowd Affiliations and College Adjustment

    Science.gov (United States)

    Hopmeyer, Andrea; Troop-Gordon, Wendy; Medovoy, Tal; Fischer, Jesse

    2017-01-01

    Crowd affiliations are integral to academic functioning and school adjustment during adolescence. However, less is known about crowd structures within institutions of higher education. The current study was designed to validate the College Peer Crowd Questionnaire (CPCQ), an instrument designed to assess college students' self-reported crowd…

  7. Developmental Changes during Childhood in Single-Letter Acuity and Its Crowding by Surrounding Contours

    Science.gov (United States)

    Jeon, Seong Taek; Hamid, Joshua; Maurer, Daphne; Lewis, Terri L.

    2010-01-01

    Crowding refers to impaired target recognition caused by surrounding contours. We investigated the development of crowding in central vision by comparing single-letter and crowding thresholds in groups of 5-year-olds, 8-year-olds, 11-year-olds, and adults. The task was to discriminate the orientation of a Sloan letter E. Single-letter thresholds,…

  8. The correlation between pain perception among patients with six different orthodontic archwires and the degree of dental crowding

    Directory of Open Access Journals (Sweden)

    Marković Evgenija

    2015-01-01

    Full Text Available Introduction. Forces generated in orthodontic treatment with fixed appliances create tension and compression zones in the periodontal ligament resulting in a painful experience for patients. In the first phase of orthodontic treatment, when leveling of teeth is needed, nickel-titanium (NiTi archwires can be completely engaged in brackets, even in the cases of extreme crowding, exerting small forces. There is a great individual variation in the pain perception related to the application of orthodontic forces. Objective. The aim of this study was to investigate the pain perception among patients with dental crowding after insertion of six different NiTi orthodontic archwires as a part of fixed appliances in the first stage of orthodontic treatment. Methods. The study was conducted on a sample of 189 orthodontic patients receiving one of six different either superelastic or heat activated NiTi archwires, in the first phase of orthodontic treatment. Pain perception was evaluated in groups of patients with different degree of crowding. The modified McGill Pain Questionnaire with Visual Analogue Scale was used to evaluate the quality and intensity of pain. Statistical analysis was performed using simple descriptive statistics, and Pearson`s chi-square test with statistical significance of p<0.05. Results. Majority of patients reported pain as discomfort or pressure of moderate intensity caused by chewing or biting, started within 12 hours, carried on for 3-4 days, and decreased over time without self-medication. Conclusion. No correlation was found between pain perception among patients with different types of NiTi archwires and the degree of crowding.

  9. Distributed Medical Image Analysis and Diagnosis through Crowd-Sourced Games: A Malaria Case Study

    Science.gov (United States)

    Mavandadi, Sam; Dimitrov, Stoyan; Feng, Steve; Yu, Frank; Sikora, Uzair; Yaglidere, Oguzhan; Padmanabhan, Swati; Nielsen, Karin; Ozcan, Aydogan

    2012-01-01

    In this work we investigate whether the innate visual recognition and learning capabilities of untrained humans can be used in conducting reliable microscopic analysis of biomedical samples toward diagnosis. For this purpose, we designed entertaining digital games that are interfaced with artificial learning and processing back-ends to demonstrate that in the case of binary medical diagnostics decisions (e.g., infected vs. uninfected), with the use of crowd-sourced games it is possible to approach the accuracy of medical experts in making such diagnoses. Specifically, using non-expert gamers we report diagnosis of malaria infected red blood cells with an accuracy that is within 1.25% of the diagnostics decisions made by a trained medical professional. PMID:22606353

  10. Distributed medical image analysis and diagnosis through crowd-sourced games: a malaria case study.

    Directory of Open Access Journals (Sweden)

    Sam Mavandadi

    Full Text Available In this work we investigate whether the innate visual recognition and learning capabilities of untrained humans can be used in conducting reliable microscopic analysis of biomedical samples toward diagnosis. For this purpose, we designed entertaining digital games that are interfaced with artificial learning and processing back-ends to demonstrate that in the case of binary medical diagnostics decisions (e.g., infected vs. uninfected, with the use of crowd-sourced games it is possible to approach the accuracy of medical experts in making such diagnoses. Specifically, using non-expert gamers we report diagnosis of malaria infected red blood cells with an accuracy that is within 1.25% of the diagnostics decisions made by a trained medical professional.

  11. Computer jargon explained

    CERN Document Server

    Enticknap, Nicholas

    2014-01-01

    Computer Jargon Explained is a feature in Computer Weekly publications that discusses 68 of the most commonly used technical computing terms. The book explains what the terms mean and why the terms are important to computer professionals. The text also discusses how the terms relate to the trends and developments that are driving the information technology industry. Computer jargon irritates non-computer people and in turn causes problems for computer people. The technology and the industry are changing so rapidly; it is very hard even for professionals to keep updated. Computer people do not

  12. Track-based event recognition in a realistic crowded environment

    NARCIS (Netherlands)

    Huis, J.R. van; Bouma, H.; Baan, J.; Burghouts, G.J.; Eendebak, P.T.; Hollander, R.J.M.; Dijk, J.; Rest, J.H.C. van

    2014-01-01

    Automatic detection of abnormal behavior in CCTV cameras is important to improve the security in crowded environments, such as shopping malls, airports and railway stations. This behavior can be characterized at different time scales, e.g., by small-scale subtle and obvious actions or by large-scale

  13. Wikipedia and the Wisdom of Crowds: A Student Project

    Science.gov (United States)

    Barnhisel, Greg; Rapchak, Marcia

    2014-01-01

    Students in a senior English class examined the question of whether the "wisdom of experts" or "the wisdom of crowds" is more reliable and useful in a writing course by engaging in a parallel Wikipedia project. Each student either created a new entry or made significant changes to an existing Wikipedia entry, tracked changes to…

  14. Wisdom of the crowd and natural resource management.

    Science.gov (United States)

    Arlinghaus, Robert; Krause, Jens

    2013-01-01

    The 'wisdom of the crowd' approach suggests that independent estimates of natural resource sizes provided by resource users can be aggregated to approximate true stock sizes. If this hypothesis gains empirical support, an important contributor to sustainable natural resource management in data-poor situations has appeared on the horizon. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Traumatic asphyxia following stadium crowd surge: stadium factors affecting outcome.

    Science.gov (United States)

    DeAngeles, D; Schurr, M; Birnbaum, M; Harms, B

    1998-10-01

    Stadium crowd surges frequently occur following major athletic events. A recent crowd surge injured more than 80 persons by trampling and/or crushing. This incident was reviewed to identify injury patterns consistent with crush-related injury. In addition, the incident was reviewed to determine which stadium policy and design factors may have potentiated this event. A recent crowd surge occurred following a college football game. This resulted in 86 people being transported to the University of Wisconsin and other area hospitals. All charts were reviewed to evaluate patient outcomes. The stadium was examined as were security system video tapes to evaluate stadium factors that contributed to this event. Current policies were obtained through the university sports administration. Of 86 patients transported for evaluation of stadium-related injuries, 10 were treated for traumatic asphyxia. Other injuries requiring hospital admission included musculo-skeletal trauma in two patients and one grade II liver injury. Six others were admitted overnight for observation. Several stadium factors were identified that contributed to the event, and appropriate changes in crowd control policies and stadium design were instated to prevent recurrence. This report details the largest single report of traumatic asphyxia second to the England Hillsborough disaster. Several stadium factors were identified that resulted in crush-related injury. Cooperative review and modification of stadium policies and design may prevent such events in the future.

  16. Crowd science user contribution patterns and their implications

    Science.gov (United States)

    Sauermann, Henry; Franzoni, Chiara

    2015-01-01

    Scientific research performed with the involvement of the broader public (the crowd) attracts increasing attention from scientists and policy makers. A key premise is that project organizers may be able to draw on underused human resources to advance research at relatively low cost. Despite a growing number of examples, systematic research on the effort contributions volunteers are willing to make to crowd science projects is lacking. Analyzing data on seven different projects, we quantify the financial value volunteers can bring by comparing their unpaid contributions with counterfactual costs in traditional or online labor markets. The volume of total contributions is substantial, although some projects are much more successful in attracting effort than others. Moreover, contributions received by projects are very uneven across time-a tendency toward declining activity is interrupted by spikes typically resulting from outreach efforts or media attention. Analyzing user-level data, we find that most contributors participate only once and with little effort, leaving a relatively small share of users who return responsible for most of the work. Although top contributor status is earned primarily through higher levels of effort, top contributors also tend to work faster. This speed advantage develops over multiple sessions, suggesting that it reflects learning rather than inherent differences in skills. Our findings inform recent discussions about potential benefits from crowd science, suggest that involving the crowd may be more effective for some kinds of projects than others, provide guidance for project managers, and raise important questions for future research.

  17. Nonlinear Effects in Examples of Crowd Evacuation Scenarios

    DEFF Research Database (Denmark)

    Starke, Jens; Berg Thomsen, Kristian; Sørensen, Asger

    2014-01-01

    Severe accidents with many fatalities have occurred when too many pedestrians had to maneuver in too tight surroundings, as during evacuations of mass events. This demonstrates the importance of a better general understanding of pedestrians and emergent complex behavior in crowds. To this end, we...

  18. Which updates during an equity crowdfunding campaign increase crowd participation?

    NARCIS (Netherlands)

    Block, J. (Jörn); Hornuf, L. (Lars); Moritz, A. (Alexandra)

    2017-01-01

    textabstractStart-ups often post updates during equity crowdfunding campaigns. However, little is known about the effects of such updates on crowd participation. We investigate this question by using hand-collected data from 71 funding campaigns and 39,399 investment decisions on two German equity

  19. Crowd Analysis by Using Optical Flow and Density Based Clustering

    DEFF Research Database (Denmark)

    Santoro, Francesco; Pedro, Sergio; Tan, Zheng-Hua

    2010-01-01

    In this paper, we present a system to detect and track crowds in a video sequence captured by a camera. In a first step, we compute optical flows by means of pyramidal Lucas-Kanade feature tracking. Afterwards, a density based clustering is used to group similar vectors. In the last step...

  20. DNA strand exchange catalyzed by molecular crowding in PEG solutions

    KAUST Repository

    Feng, Bobo

    2010-01-01

    DNA strand exchange is catalyzed by molecular crowding and hydrophobic interactions in concentrated aqueous solutions of polyethylene glycol, a discovery of relevance for understanding the function of recombination enzymes and with potential applications to DNA nanotechnology. © 2010 The Royal Society of Chemistry.

  1. The Effects of Crowding Stress, Different Diets and Different Size ...

    African Journals Online (AJOL)

    The Effects of Crowding Stress, Different Diets and Different Size Classes on the Growth Rate of Clarias gariepinus. ... showed that: at constant area, growth rate of Clarias gariepinus reduced by as much as 75% when the density was increased from one to three individuals per square metre - regardless of food supplied.

  2. Effect of crowding stress on growth performance and carcass quality ...

    African Journals Online (AJOL)

    /m3) fed 40%CP with a mean value of 5.33±1.05, while the lowest stocking density (10 fish/m3)fed 45%CP had the least mean value of 3.97±0.58. The results of this experiment showed that juvenile African catfish may adjust to crowding stress ...

  3. Crowding, Proximity, Inmate Violence, and the Eighth Amendment.

    Science.gov (United States)

    Anson, Richard H.; Hancock, Barry W.

    1992-01-01

    Rejects federal court ruling that prison crowding must be considered in light of total space availability of given institution. Notes variability in body buffer zones for each individual inmate, aggression potential, and variability between violent and nonviolent inmates. Contends that correctional practitioners should allocate institutional space…

  4. Explaining the Oxbridge Figures.

    Science.gov (United States)

    Davies, Bronwyn; Harre, Rom

    1989-01-01

    Rejects sociobiological theories on female academic achievement and bases findings on social structure to explain why undergraduate women at Oxford University (England) achieve fewer first places and more second places in class honors. Bases theory on bipolarity of gender as an organizing principle of society. Claims that the double bind of social…

  5. Global and local magnetic mapping using CrowdMag data

    Science.gov (United States)

    Saltus, R.; Nair, M. C.

    2016-12-01

    NOAA's National Centers for Environmental Information (NCEI), in partnership with the University of Colorado's CIRES develop magnetic field models to aid navigation, resource exploration and scientific research. We use observatories, satellites and ship/airborne surveys to map and model the Earth's magnetic field. However, the available measurements leave gaps in coverage, particularly for short-wavelength anomalies associated with man-made infrastructure ("urban noise"). In 2014, we started a project to address these gaps through the collection of vector magnetic data from digital magnetometers in smartphones. In October 2014, we released the "CrowdMag" Android and iOS apps for harvesting data from phones. Currently, the CrowdMag project has more than 10,000 enthusiastic users contributing more than 12 million magnetic data measurements from around the world. We present the first analysis results from the crowdsourced magnetic data. A global magnetic model derived solely from CrowdMag data is consistent to degree and order 4 with satellite-derived models such as World Magnetic Model. A unique contribution of CrowdMag project is the collection of ground level magnetic data in densely populated regions with an unprecedented spatial resolution. To demonstrate, we generated a magnetic map (by binning the data collected in 200x200m cells) of central Boulder, Colorado using 170,000 data points collected by about 60 devices over the duration October 2014- January 2016. The median value is consistent with the expected magnitude of the Earth's background magnetic field. The standard deviation of the CrowdMag total field (F) values is much higher than the expected natural (i.e., diurnal and geologic) magnetic field variation. However, the phone's magnetometer is sensitive enough to capture the larger magnitude magnetic signature from the urban magnetic sources. We discuss the potential reliability of crowdsourced magnetic maps and their applications to navigation and other

  6. Crowding at Cape Lookout National Seashore: an examination of the influence of visitor characteristics on encounter norms and perceived crowding

    Science.gov (United States)

    David Alan Graefe; Hans Vogelsong

    2009-01-01

    Outdoor recreation researchers have typically defined "crowding" as a negative evaluation of the social atmosphere of an area. According to normative theory, individuals have standards (norms) regarding the appropriateness of different levels and types of recreational use. The purpose of this study was to examine the influences of visitor characteristics on...

  7. Crowd-Sourced Assessment of Technical Skills: Differentiating Animate Surgical Skill Through the Wisdom of Crowds.

    Science.gov (United States)

    Holst, Daniel; Kowalewski, Timothy M; White, Lee W; Brand, Timothy C; Harper, Jonathan D; Sorensen, Mathew D; Truong, Mireille; Simpson, Khara; Tanaka, Alyssa; Smith, Roger; Lendvay, Thomas S

    2015-10-01

    Objective quantification of surgical skill is imperative as we enter a healthcare environment of quality improvement and performance-based reimbursement. The gold standard tools are infrequently used due to time-intensiveness, cost inefficiency, and lack of standard practices. We hypothesized that valid performance scores of surgical skill can be obtained through crowdsourcing. Twelve surgeons of varying robotic surgical experience performed live porcine robot-assisted urinary bladder closures. Blinded video-recorded performances were scored by expert surgeon graders and by Amazon's Mechanical Turk crowdsourcing crowd workers using the Global Evaluative Assessment of Robotic Skills tool assessing five technical skills domains. Seven expert graders and 50 unique Mechanical Turkers (each paid $0.75/survey) evaluated each video. Global assessment scores were analyzed for correlation and agreement. Six hundred Mechanical Turkers completed the surveys in less than 5 hours, while seven surgeon graders took 14 days. The duration of video clips ranged from 2 to 11 minutes. The correlation coefficient between the Turkers' and expert graders' scores was 0.95 and Cronbach's Alpha was 0.93. Inter-rater reliability among the surgeon graders was 0.89. Crowdsourcing surgical skills assessment yielded rapid inexpensive agreement with global performance scores given by expert surgeon graders. The crowdsourcing method may provide surgical educators and medical institutions with a boundless number of procedural skills assessors to efficiently quantify technical skills for use in trainee advancement and hospital quality improvement.

  8. Crowd Behaviour during High-Stress Evacuations in an Immersive Virtual Environment

    CERN Document Server

    Moussaïd, Mehdi; Thrash, Tyler; Sumner, Robert W; Gross, Markus; Helbing, Dirk; Hölscher, Christoph

    2016-01-01

    Understanding the collective dynamics of crowd movements during stressful emergency situations is central to reducing the risk of deadly crowd disasters. Yet, their systematic experimental study remains a challenging open problem due to ethical and methodological constraints. In this paper, we demonstrate the viability of shared 3D virtual environments as an experimental platform for conducting crowd experiments with real people. In particular, we show that crowds of real human subjects moving and interacting in an immersive 3D virtual environment exhibit typical patterns of real crowds as observed in real-life crowded situations. These include the manifestation of social conventions and the emergence of self-organized patterns during egress scenarios. High-stress evacuation experiments conducted in this virtual environment reveal movements characterized by mass herding and dangerous overcrowding as they occur in crowd disasters. We describe the behavioral mechanisms at play under such extreme conditions and ...

  9. "Psychology of the crowd during crisis situations - how is able to dispose with that one. (Law and psychological aspects.)"

    OpenAIRE

    ŠKOLKOVÁ, Věra

    2010-01-01

    Use of scientific knowledge in crowd psychology is low-level presently. Even the individual branches of the Integrated Rescue System (IRS) do not use crowd psychology, in most cases, for dealing with crisis situations. The fundamental factor in understanding crowd psychology is the fact that crowd is a social aggregate and someone{\\crq}s presence in a crowd gives rise to new qualities different from those of individuals present in a crowd. The rise of special qualities of a crowd is caused by...

  10. Linear Algebra Thoroughly Explained

    CERN Document Server

    Vujičić, Milan

    2008-01-01

    Linear Algebra Thoroughly Explained provides a comprehensive introduction to the subject suitable for adoption as a self-contained text for courses at undergraduate and postgraduate level. The clear and comprehensive presentation of the basic theory is illustrated throughout with an abundance of worked examples. The book is written for teachers and students of linear algebra at all levels and across mathematics and the applied sciences, particularly physics and engineering. It will also be an invaluable addition to research libraries as a comprehensive resource book for the subject.

  11. Statistical analysis of passenger-crowding in bus transport network of Harbin

    Science.gov (United States)

    Hu, Baoyu; Feng, Shumin; Li, Jinyang; Zhao, Hu

    2018-01-01

    Passenger flow data is indispensable but rare in the study of public transport networks. In this study, we focus on the passenger-crowding characteristics of the bus transport network of Harbin (BTN-H) based on passenger flow investigation. The three frequency histograms for all the uplinks and downlinks in Harbin are presented, including passengers on the bus at each section, crowding coefficients, and position parameters of crowded sections. The differences in crowding position are analyzed on each route. The distributions of degree and crowding degree (in directed space L) follow an exponential law. The new finding indicates that there are many stations with few crowded sections and a few stations with many crowded sections. The distributions of path length and crowded length (in directed space P) are presented based on the minimum transfer times, and it is found that they can be fitted by a composite Gaussian function and a Gaussian function, respectively. The stations and paths can be divided into three crowd levels. We conclude that BTN-H is crowded from a network-based perspective.

  12. Quality-Aware Incentive Mechanism for Mobile Crowd Sensing

    Directory of Open Access Journals (Sweden)

    Ling-Yun Jiang

    2017-01-01

    Full Text Available Mobile crowd sensing (MCS is a novel sensing paradigm which can sense human-centered daily activities and the surrounding environment. The impact of mobility and selfishness of participants on the data reliability cannot be ignored in most mobile crowd sensing systems. To address this issue, we present a universal system model based on the reverse auction framework and formulate the problem as the Multiple Quality Multiple User Selection (MQMUS problem. The quality-aware incentive mechanism (QAIM is proposed to meet the quality requirement of data reliability. We demonstrate that the proposed incentive mechanism achieves the properties of computational efficiency, individual rationality, and truthfulness. And meanwhile, we evaluate the performance and validate the theoretical properties of our incentive mechanism through extensive simulation experiments.

  13. Public Service Motivation and Monetary Incentives: Substitutes or Motivation Crowding?

    DEFF Research Database (Denmark)

    Jacobsen, Christian Bøtcher

    2011-01-01

    Motivation is probably one of the most important determinants for organizational performance, because it stimulates effort and effective behaviors among people in the organization. But what type of motivation should public managers rely on? The PSM literature has argued that public service....... Using panel data from two surveys (2009 and 2011) of Danish physiotherapists (N=1.433), this study sheds more light on this chicken and egg debate. The results find no support for the PSM argument, but good support for the motivation crowding expectations. The results indicate that managers should...... motivation is the most important type of motivation in the delivery of public service, because it substitutes for egoistic motivation. Organizations whose members have high levels of PSM are therefore expected to be less dependent on utilitarian motivators such as monetary incentives. Motivation crowding...

  14. Emergence of collective intonation in the musical performance of crowds

    Science.gov (United States)

    Lacasa, Lucas

    2016-09-01

    The average individual is typically a mediocre singer, with a rather restricted capacity to sing a melody in tune. Yet when many singers are assembled to perform collectively, the resulting melody of the crowd is suddenly perceived by an external listener as perfectly tuned —as if it was actually a choral performance— even if each individual singer is out of tune. This collective phenomenon is an example of a wisdom of crowds effect that can be routinely observed in music concerts or other social events, when a group of people spontaneously sings at unison. In this paper we rely on the psychoacoustic properties of pitch and provide a simple mechanistic explanation for the onset of this emergent behavior.

  15. Disaster Risk Reduction through Innovative Uses of Crowd Sourcing (Invited)

    Science.gov (United States)

    Berger, J.; Greene, M.

    2010-12-01

    Crowd sourcing can be described as a method of distributed problem-solving. It takes advantage of the power of the crowd, which can in some cases be a community of experts and in other cases the collective insight of a broader range of contributors with varying degrees of domain knowledge. The term crowd sourcing was first used by Jeff Howe in a June 2006 Wired magazine article “The Rise of Crowdsourcing,” and is a combination of the terms “crowd” and “outsourcing.” Some commonly known examples of crowd sourcing, in its broadest sense, include Wikepedia, distributed participatory design projects, and consumer websites such as Yelp and Angie’s List. The popularity and success of early large-scale crowd sourcing activities is made possible through leveraging Web 2.0 technologies that allow for mass participation from distributed individuals. The Earthquake Engineering Research Institute (EERI) in Oakland, California recently participated in two crowd sourcing projects. One was initiated and coordinated by EERI, while in the second case EERI was invited to contribute once the crowd sourcing activity was underway. In both projects there was: 1) the determination of a problem or set of tasks that could benefit immediately from the engagement of an informed volunteer group of professionals; 2) a segmenting of the problem into discrete pieces that could be completed in a short period of time (from ten minutes to four hours); 3) a call to action, where an interested community was made aware of the project; and 4) the collection, aggregation, vetting and ultimately distribution of the results in a relatively short period of time. The first EERI crowd sourcing example was the use of practicing engineers and engineering students in California to help estimate the number of pre-1980 concrete buildings in the high seismic risk counties in the state. This building type is known to perform poorly in earthquakes, and state officials were interested in understanding

  16. Crowd-Sourcing the Aesthetics of Platform Games

    DEFF Research Database (Denmark)

    Shaker, Noor; Yannakakis, Georgios N.; Togelius, Julian

    2014-01-01

    What are the aesthetics of platform games and what makes a platform level engaging, challenging and/or frustrating? We attempt to answer such questions through mining a large-set of crowd-sourced gameplay data of a clone of the classic platform game Super Mario Bros. The data consists of 40 short...... game levels that differ along six key level design parameters. Collectively, these levels are played 1560 times over the Internet and the perceived experience is annotated by experiment participants via self-reported ranking (pairwise preferences). Given the wealth of this crowd-sourced data, as all...... details about players’ in-game behaviour are logged, the problem becomes one of extracting meaningful numerical features at the appropriate level of abstraction for the construction of generic computational models of player experience and, thereby, game aesthetics. We explore dissimilar types of features...

  17. Explaining embodied cognition results.

    Science.gov (United States)

    Lakoff, George

    2012-10-01

    From the late 1950s until 1975, cognition was understood mainly as disembodied symbol manipulation in cognitive psychology, linguistics, artificial intelligence, and the nascent field of Cognitive Science. The idea of embodied cognition entered the field of Cognitive Linguistics at its beginning in 1975. Since then, cognitive linguists, working with neuroscientists, computer scientists, and experimental psychologists, have been developing a neural theory of thought and language (NTTL). Central to NTTL are the following ideas: (a) we think with our brains, that is, thought is physical and is carried out by functional neural circuitry; (b) what makes thought meaningful are the ways those neural circuits are connected to the body and characterize embodied experience; (c) so-called abstract ideas are embodied in this way as well, as is language. Experimental results in embodied cognition are seen not only as confirming NTTL but also explained via NTTL, mostly via the neural theory of conceptual metaphor. Left behind more than three decades ago is the old idea that cognition uses the abstract manipulation of disembodied symbols that are meaningless in themselves but that somehow constitute internal "representations of external reality" without serious mediation by the body and brain. This article uniquely explains the connections between embodied cognition results since that time and results from cognitive linguistics, experimental psychology, computational modeling, and neuroscience. Copyright © 2012 Cognitive Science Society, Inc.

  18. HUMOR: A Crowd-Annotated Spanish Corpus for Humor Analysis

    OpenAIRE

    Castro, Santiago; Cubero, Matías; Garat, Diego; Moncecchi, Guillermo

    2017-01-01

    Computational Humor, as the name implies, studies humor from a computational perspective, and it fosters several tasks, such as humor recognition, humor generation and humor scoring. The area has been little explored, making it attractive to tackle by novel Natural Language Processing and Machine Learning techniques. However, human-curated data is necessary. In this work we present a corpus of almost 40,000 tweets written in Spanish and crowd-annotated by their humor and funniness value with ...

  19. Crowded, Confined, and Frustrated: Dynamics of Molecules Tethered to Nanoparticles

    KAUST Repository

    Agarwal, Praveen

    2012-12-01

    Above a critical chemistry-dependent molecular weight, all polymer molecules entangle and, as a result, exhibit slow dynamics, enhanced viscosity, and elasticity. Herein we report on the dynamics of low molecular weight polymers tethered to nanoparticles and find that even conventionally unentangled chains manifest dynamical features similar to entangled, long-chain molecules. Our findings are shown to imply that crowding and confinement of polymers on particles produce topological constraints analogous to those in entangled systems. © 2012 American Physical Society.

  20. Adding more junior residents may worsen emergency department crowding.

    Directory of Open Access Journals (Sweden)

    Takahisa Kawano

    Full Text Available BACKGROUND: Although increasing staff numbers during shifts when emergency department (ED crowding is severe can help meet patient demand, it remains unclear how different types of added staff, particularly junior residents, may affect crowding. METHODS: To identify associations between types of staff and ED crowding, we conducted a cross-sectional, single-center study in the ED of a large, teaching hospital in Japan between January and December 2012. Patients who visited the ED during the study period were enrolled. We excluded (1 patients previously scheduled to visit the ED, and (2 neonates transferred from other hospitals. During the study period, 27,970 patients were enrolled. Types of staff analyzed were junior (first and second year residents, senior (third to fifth year residents, attending (board-certified physicians, and nurses. A generalized linear model was applied to length of ED stay for all patients as well as admitted and discharged patients to quantify an association with the additional staff. RESULTS: In the model, addition of one attending physician or senior resident was associated with decreased length of ED stay for total patients by 3.88 or 1.64 minutes, respectively (95% CI, 2.20-5.56 and 0.81-2.48 minutes; while additional nursing staff had no association. Surprisingly, however, one additional junior resident was associated with prolonged length of ED stay for total patients by 0.97 minutes (95% CI 0.37-1.57 minutes and for discharged patients by 1.01 minutes (95% CI 0.45-1.59 minutes. CONCLUSION: Staffing adjustments aimed at alleviating ED crowding should focus on adding more senior staff during peak-volume shifts.

  1. Traffic instabilities in self-organized pedestrian crowds.

    Directory of Open Access Journals (Sweden)

    Mehdi Moussaïd

    Full Text Available In human crowds as well as in many animal societies, local interactions among individuals often give rise to self-organized collective organizations that offer functional benefits to the group. For instance, flows of pedestrians moving in opposite directions spontaneously segregate into lanes of uniform walking directions. This phenomenon is often referred to as a smart collective pattern, as it increases the traffic efficiency with no need of external control. However, the functional benefits of this emergent organization have never been experimentally measured, and the underlying behavioral mechanisms are poorly understood. In this work, we have studied this phenomenon under controlled laboratory conditions. We found that the traffic segregation exhibits structural instabilities characterized by the alternation of organized and disorganized states, where the lifetime of well-organized clusters of pedestrians follow a stretched exponential relaxation process. Further analysis show that the inter-pedestrian variability of comfortable walking speeds is a key variable at the origin of the observed traffic perturbations. We show that the collective benefit of the emerging pattern is maximized when all pedestrians walk at the average speed of the group. In practice, however, local interactions between slow- and fast-walking pedestrians trigger global breakdowns of organization, which reduce the collective and the individual payoff provided by the traffic segregation. This work is a step ahead toward the understanding of traffic self-organization in crowds, which turns out to be modulated by complex behavioral mechanisms that do not always maximize the group's benefits. The quantitative understanding of crowd behaviors opens the way for designing bottom-up management strategies bound to promote the emergence of efficient collective behaviors in crowds.

  2. The Imagination of Crowds : The efficacy of a false hypothesis

    OpenAIRE

    Martinez Tagliavia, Francesca

    2013-01-01

    International audience; Literature produced around the notion of charisma (attributed to the chief, the master, the leader, the Father, the guru, the boss, etc.) has supplied, in the past, arguments for Nazi and Fascist propaganda (Cohen 2013; De Felice 1968). This seems clear by Hitler and Mussolini's great interest for Gustave Le Bon's The Crowd: A Study of the Popular Mind (1895), translated in English one year later (Le Bon 2001). How does Le Bon describe the absence of control, the excep...

  3. The multi-niche crowding genetic algorithm: Analysis and applications

    Energy Technology Data Exchange (ETDEWEB)

    Cedeno, Walter [Univ. of California, Davis, CA (United States)

    1995-09-01

    The ability of organisms to evolve and adapt to the environment has provided mother nature with a rich and diverse set of species. Only organisms well adapted to their environment can survive from one generation to the next, transferring on the traits, that made them successful, to their offspring. Competition for resources and the ever changing environment drives some species to extinction and at the same time others evolve to maintain the delicate balance in nature. In this disertation we present the multi-niche crowding genetic algorithm, a computational metaphor to the survival of species in ecological niches in the face of competition. The multi-niche crowding genetic algorithm maintains stable subpopulations of solutions in multiple niches in multimodal landscapes. The algorithm introduces the concept of crowding selection to promote mating among members with qirnilar traits while allowing many members of the population to participate in mating. The algorithm uses worst among most similar replacement policy to promote competition among members with similar traits while allowing competition among members of different niches as well. We present empirical and theoretical results for the success of the multiniche crowding genetic algorithm for multimodal function optimization. The properties of the algorithm using different parameters are examined. We test the performance of the algorithm on problems of DNA Mapping, Aquifer Management, and the File Design Problem. Applications that combine the use of heuristics and special operators to solve problems in the areas of combinatorial optimization, grouping, and multi-objective optimization. We conclude by presenting the advantages and disadvantages of the algorithm and describing avenues for future investigation to answer other questions raised by this study.

  4. The effect of music tempo on perceived crowding in retailing

    OpenAIRE

    Fiksdal, Taisiya; Hua, Wen

    2016-01-01

    Masteroppgave(MSc) in Master of Science in Strategic Marketing Management - Handelshøyskolen BI, 2016 In the marketing field the influence of in-store atmospherics on consumers’ shopping behavior is widely accepted. We seek to understand the effects of instore music tempo on perceived crowding and how music tempo can affect emotions, arousal and perceived control occurring in retail stores. Hence, our research questions are the following: Does music tempo influence the perce...

  5. Adding More Junior Residents May Worsen Emergency Department Crowding

    Science.gov (United States)

    Kawano, Takahisa; Nishiyama, Kei; Hayashi, Hiroyuki

    2014-01-01

    Background Although increasing staff numbers during shifts when emergency department (ED) crowding is severe can help meet patient demand, it remains unclear how different types of added staff, particularly junior residents, may affect crowding. Methods To identify associations between types of staff and ED crowding, we conducted a cross-sectional, single-center study in the ED of a large, teaching hospital in Japan between January and December 2012. Patients who visited the ED during the study period were enrolled. We excluded (1) patients previously scheduled to visit the ED, and (2) neonates transferred from other hospitals. During the study period, 27,970 patients were enrolled. Types of staff analyzed were junior (first and second year) residents, senior (third to fifth year) residents, attending (board-certified) physicians, and nurses. A generalized linear model was applied to length of ED stay for all patients as well as admitted and discharged patients to quantify an association with the additional staff. Results In the model, addition of one attending physician or senior resident was associated with decreased length of ED stay for total patients by 3.88 or 1.64 minutes, respectively (95% CI, 2.20–5.56 and 0.81–2.48 minutes); while additional nursing staff had no association. Surprisingly, however, one additional junior resident was associated with prolonged length of ED stay for total patients by 0.97 minutes (95% CI 0.37–1.57 minutes) and for discharged patients by 1.01 minutes (95% CI 0.45–1.59 minutes). Conclusion Staffing adjustments aimed at alleviating ED crowding should focus on adding more senior staff during peak-volume shifts. PMID:25369063

  6. The Wisdom of e-crowds: Can Masses Create Value?

    Directory of Open Access Journals (Sweden)

    Wieczerzycki Marcin

    2016-09-01

    Full Text Available With the rising popularity of the Internet, interactions between companies and their consumers have become more common and meaningful. Researchers often tend to apply the metaphor of community to these on-line networks of B2C relationships. However, this term implies durability and a long-term orientation. It does not cover more incidental, short-lived groups of consumers, who therefore should not be treated as communities. The purpose of this paper is to explore the ability of these short-term, collective consumer phenomena (addressed as e-crowds within the scope of this paper to create value. Based on a critical literature analysis that considers works from several different fields of knowledge (including management, economics, psychology and media studies and empirical examples, we argue that while lacking a complex internal organization, e-crowds are capable of creating use, exchange and sign value when certain conditions are met. However, they are equally likely to perform value-destroying activities, which present real risks for companies that interact with e-crowds.

  7. Oropharyngeal Crowding Closely Relates to Aggravation of OSA.

    Science.gov (United States)

    Ito, Eiki; Tsuiki, Satoru; Maeda, Keiko; Okajima, Isa; Inoue, Yuichi

    2016-08-01

    Obesity is known to be an important risk factor for OSA; however, OSA can also be seen in nonobese patients with a small maxilla and/or mandible as well as in all obese patients with such features. Thus, we hypothesized that regional factors, oropharyngeal crowding associated with fat deposition, and maxillomandibular enclosure size closely related to the severity of OSA. A total of 703 male Japanese subjects were enrolled; theywere classified into obese (BMI ≥ 30 kg/m(2); n = 158) and nonobese (BMI OSA subjects, although BMI and TG/LFC were significantly associated with AHI in both groups. In particular, the contribution of TG/LFC to AHI was larger than that of BMI in the obese group. Oropharyngeal crowding is a local anatomic factor that independently relates to the severity of OSA in both obese and nonobese patients; the more crowded the upper airway, the more severe the OSA. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  8. Conservation of Energy for Crowd Self-Driven Motion

    CERN Document Server

    Wang, Peng; Marsh, Kerry L

    2013-01-01

    For centuries, how an object moves given external forces is characterized by physical laws. As for creatures like human, their movements are self-driven, and the driving forces are generated by intention of people in a psychological sense. How to capture this characteristic in consistency with known physics laws is meaningful to understand human behaviors. By investigating a Newtonian-like model of a pedestrian, this paper presents a fluid-like model of crowd, showing that the physical concept of energy is also suited for psychological study of human collective behaviors. An energy balance equation is derived to characterize how the energy is transformed between the psychological forms and physical forms: the psychological drive arises as a potential form of energy, which aims at either accelerating or compressing a crowd as transformed to energy in physical forms (e.g., kinetic energy or static energy). If such transformation cannot be realized, disorder of the crowd may appear as a possible result. Based on...

  9. Case Report. Prosthetic Rehabilitation of Crowded Maxillary Anterior Teeth

    Directory of Open Access Journals (Sweden)

    Markovics Emese Rita

    2017-03-01

    Full Text Available In this case report we present the aesthetical correction of crowded anterior teeth in a patient who has refused the orthodontic treatment. We also discuss how this correction can be resolved from the point of view of dental prosthetic and what measurements can be helpful in order to collect the data used to restore a satisfying smile on the patient’s face using dental ceramic restoration. Case presentation: A 32-year-old patient complained about his crowded incisors. We examined the incisal curvature, the proportion between the height and the width of the teeth, and the relation between the widths of the teeth and the golden proportion. The results of the measurements were compared to the characteristic values of the ideal denture. After the examination of the dental plaster cast, calculating the difference between the existing space and the necessary space, we were able to calculate the lack of space, which caused the crowded teeth. Conclusion: Along the prosthetic planning, these measurements may serve as a guideline to the dentist as an objective basis for the formation of an aesthetic denture and smile.

  10. A solution to the single-question crowd wisdom problem.

    Science.gov (United States)

    Prelec, Dražen; Seung, H Sebastian; McCoy, John

    2017-01-25

    Once considered provocative, the notion that the wisdom of the crowd is superior to any individual has become itself a piece of crowd wisdom, leading to speculation that online voting may soon put credentialed experts out of business. Recent applications include political and economic forecasting, evaluating nuclear safety, public policy, the quality of chemical probes, and possible responses to a restless volcano. Algorithms for extracting wisdom from the crowd are typically based on a democratic voting procedure. They are simple to apply and preserve the independence of personal judgment. However, democratic methods have serious limitations. They are biased for shallow, lowest common denominator information, at the expense of novel or specialized knowledge that is not widely shared. Adjustments based on measuring confidence do not solve this problem reliably. Here we propose the following alternative to a democratic vote: select the answer that is more popular than people predict. We show that this principle yields the best answer under reasonable assumptions about voter behaviour, while the standard 'most popular' or 'most confident' principles fail under exactly those same assumptions. Like traditional voting, the principle accepts unique problems, such as panel decisions about scientific or artistic merit, and legal or historical disputes. The potential application domain is thus broader than that covered by machine learning and psychometric methods, which require data across multiple questions.

  11. Bayesian network model of crowd emotion and negative behavior

    Science.gov (United States)

    Ramli, Nurulhuda; Ghani, Noraida Abdul; Hatta, Zulkarnain Ahmad; Hashim, Intan Hashimah Mohd; Sulong, Jasni; Mahudin, Nor Diana Mohd; Rahman, Shukran Abd; Saad, Zarina Mat

    2014-12-01

    The effects of overcrowding have become a major concern for event organizers. One aspect of this concern has been the idea that overcrowding can enhance the occurrence of serious incidents during events. As one of the largest Muslim religious gathering attended by pilgrims from all over the world, Hajj has become extremely overcrowded with many incidents being reported. The purpose of this study is to analyze the nature of human emotion and negative behavior resulting from overcrowding during Hajj events from data gathered in Malaysian Hajj Experience Survey in 2013. The sample comprised of 147 Malaysian pilgrims (70 males and 77 females). Utilizing a probabilistic model called Bayesian network, this paper models the dependence structure between different emotions and negative behaviors of pilgrims in the crowd. The model included the following variables of emotion: negative, negative comfortable, positive, positive comfortable and positive spiritual and variables of negative behaviors; aggressive and hazardous acts. The study demonstrated that emotions of negative, negative comfortable, positive spiritual and positive emotion have a direct influence on aggressive behavior whereas emotion of negative comfortable, positive spiritual and positive have a direct influence on hazardous acts behavior. The sensitivity analysis showed that a low level of negative and negative comfortable emotions leads to a lower level of aggressive and hazardous behavior. Findings of the study can be further improved to identify the exact cause and risk factors of crowd-related incidents in preventing crowd disasters during the mass gathering events.

  12. Matlab for engineers explained

    CERN Document Server

    Gustafsson, Fredrik

    2003-01-01

    This book is written for students at bachelor and master programs and has four different purposes, which split the book into four parts: 1. To teach first or early year undergraduate engineering students basic knowledge in technical computations and programming using MATLAB. The first part starts from first principles and is therefore well suited both for readers with prior exposure to MATLAB but lacking a solid foundational knowledge of the capabilities of the system and readers not having any previous experience with MATLAB. The foundational knowledge gained from these interactive guided tours of the system will hopefully be sufficient for an effective utilization of MATLAB in the engineering profession, in education and in research. 2. To explain the foundations of more advanced use of MATLAB using the facilities added the last couple of years, such as extended data structures, object orientation and advanced graphics. 3. To give an introduction to the use of MATLAB in typical undergraduate courses in elec...

  13. Explaining wartime rape.

    Science.gov (United States)

    Gottschall, Jonathan

    2004-05-01

    In the years since the first reports of mass rapes in the Yugoslavian wars of secession and the genocidal massacres in Rwanda, feminist activists and scholars, human rights organizations, journalists, and social scientists have dedicated unprecedented efforts to document, explain, and seek solutions for the phenomenon of wartime rape. While contributors to this literature agree on much, there is no consensus on causal factors. This paper provides a brief overview of the literature on wartime rape in historical and ethnographical societies and a critical analysis of the four leading explanations for its root causes: the feminist theory, the cultural pathology theory, the strategic rape theory, and the biosocial theory. The paper concludes that the biosocial theory is the only one capable of bringing all the phenomena associated with wartime rape into a single explanatory context.

  14. Does Viewing Explain Doing?

    DEFF Research Database (Denmark)

    Hald, Gert Martin; Kuyper, Lisette; Adam, Philippe C G

    2013-01-01

    that, when controlling for important other factors, SEM consumption influences sexual behaviors. The small to moderate associations that emerged between SEM consumption and sexual behavior after controlling for other variables suggest that SEM is just one factor among many that may influence youth...... hierarchical multiple regression analyses to control for other factors, the association between SEM consumption and a variety of sexual behaviors was found to be significant, accounting for between 0.3% and 4% of the total explained variance in investigated sexual behaviors. CONCLUSIONS: This study suggests......INTRODUCTION: Concerns have been voiced that the use of sexually explicit materials (SEMs) may adversely affect sexual behaviors, particularly in young people. Previous studies have generally found significant associations between SEM consumption and the sexual behaviors investigated. However, most...

  15. Active Learning in Neuroscience: A Manipulative to Simulate Visual Field Defects

    Science.gov (United States)

    Li, Andrew Yue-Lin; Carvalho, Helena

    2016-01-01

    Prevalent in 20-57% of stroke patients, visual field defects have been shown to impact quality of life. Studies have shown increased risk of falling, ambulatory difficulties, impaired reading ability, and feelings of panic in crowded or unfamiliar places in patients with visual field defects. Rehabilitation, independence, and mental health may…

  16. Crowd Sourcing for Challenging Technical Problems and Business Model

    Science.gov (United States)

    Davis, Jeffrey R.; Richard, Elizabeth

    2011-01-01

    Crowd sourcing may be defined as the act of outsourcing tasks that are traditionally performed by an employee or contractor to an undefined, generally large group of people or community (a crowd) in the form of an open call. The open call may be issued by an organization wishing to find a solution to a particular problem or complete a task, or by an open innovation service provider on behalf of that organization. In 2008, the Space Life Sciences Directorate (SLSD), with the support of Wyle Integrated Science and Engineering, established and implemented pilot projects in open innovation (crowd sourcing) to determine if these new internet-based platforms could indeed find solutions to difficult technical challenges. These unsolved technical problems were converted to problem statements, also called "Challenges" or "Technical Needs" by the various open innovation service providers, and were then posted externally to seek solutions. In addition, an open call was issued internally to NASA employees Agency wide (10 Field Centers and NASA HQ) using an open innovation service provider crowd sourcing platform to post NASA challenges from each Center for the others to propose solutions). From 2008 to 2010, the SLSD issued 34 challenges, 14 externally and 20 internally. The 14 external problems or challenges were posted through three different vendors: InnoCentive, Yet2.com and TopCoder. The 20 internal challenges were conducted using the InnoCentive crowd sourcing platform designed for internal use by an organization. This platform was customized for NASA use and promoted as NASA@Work. The results were significant. Of the seven InnoCentive external challenges, two full and five partial awards were made in complex technical areas such as predicting solar flares and long-duration food packaging. Similarly, the TopCoder challenge yielded an optimization algorithm for designing a lunar medical kit. The Yet2.com challenges yielded many new industry and academic contacts in bone

  17. Constructing visual representations

    DEFF Research Database (Denmark)

    Huron, Samuel; Jansen, Yvonne; Carpendale, Sheelagh

    2014-01-01

    The accessibility of infovis authoring tools to a wide audience has been identified as a major research challenge. A key task in the authoring process is the development of visual mappings. While the infovis community has long been deeply interested in finding effective visual mappings......, comparatively little attention has been placed on how people construct visual mappings. In this paper, we present the results of a study designed to shed light on how people transform data into visual representations. We asked people to create, update and explain their own information visualizations using only...... tangible building blocks. We learned that all participants, most of whom had little experience in visualization authoring, were readily able to create and talk about their own visualizations. Based on our observations, we discuss participants’ actions during the development of their visual representations...

  18. Explaining climate danger

    Science.gov (United States)

    Oreskes, N.

    2016-12-01

    The idea of `managing planet Earth' is traceable back at least to the 1970s. Recently, it has been reformulated in the idea of a "good Anthropocene": the idea that humans should and can try to manage our planet now that we have become a planetary force. Yet available evidence and experience suggests that our prior attempts to do so have been plagued by under-estimation of the scale of the problems and over-estimation of our capacities to address them. In any case, Earth is not at risk—our planet will survive despite what we do or fail to do. Global climate change, for example, is not a problem for the planet, it is a problem for us. As the UNFCCC articulated in the 1990s, climate change matters because it is dangerous. Yet many Americans still do not understand why this is the case. I suggest that scientists can profitably focus attention on explaining this danger—why climate represents a threat to our health, well-being, and lives—and on what kinds of steps can be taken to reduce the danger.

  19. How molecular motors work in the crowded environment of living cells: coexistence and efficiency of normal and anomalous transport.

    Directory of Open Access Journals (Sweden)

    Igor Goychuk

    Full Text Available Recent experiments reveal both passive subdiffusion of various nanoparticles and anomalous active transport of such particles by molecular motors in the molecularly crowded environment of living biological cells. Passive and active microrheology reveals that the origin of this anomalous dynamics is due to the viscoelasticity of the intracellular fluid. How do molecular motors perform in such a highly viscous, dissipative environment? Can we explain the observed co-existence of the anomalous transport of relatively large particles of 100 to 500 nm in size by kinesin motors with the normal transport of smaller particles by the same molecular motors? What is the efficiency of molecular motors in the anomalous transport regime? Here we answer these seemingly conflicting questions and consistently explain experimental findings in a generalization of the well-known continuous diffusion model for molecular motors with two conformational states in which viscoelastic effects are included.

  20. Distinctive neural mechanisms supporting visual object individuation and identification.

    Science.gov (United States)

    Xu, Yaoda

    2009-03-01

    Many everyday activities, such as driving on a busy street, require the encoding of distinctive visual objects from crowded scenes. Given resource limitations of our visual system, one solution to this difficult and challenging task is to first select individual objects from a crowded scene (object individuation) and then encode their details (object identification). Using functional magnetic resonance imaging, two distinctive brain mechanisms were recently identified that support these two stages of visual object processing. While the inferior intraparietal sulcus (IPS) selects a fixed number of about four objects via their spatial locations, the superior IPS and the lateral occipital complex (LOC) encode the features of a subset of the selected objects in great detail (object shapes in this case). Thus, the inferior IPS individuates visual objects from a crowded display and the superior IPS and higher visual areas participate in subsequent object identification. Consistent with the prediction of this theory, even when only object shape identity but not its location is task relevant, this study shows that object individuation in the inferior IPS treats four identical objects similarly as four objects that are all different, whereas object shape identification in the superior IPS and the LOC treat four identical objects as a single unique object. These results provide independent confirmation supporting the dissociation between visual object individuation and identification in the brain.

  1. Altered immunity in crowded locust reduced fungal (Metarhizium anisopliae pathogenesis.

    Directory of Open Access Journals (Sweden)

    Yundan Wang

    2013-01-01

    Full Text Available The stress of living conditions, similar to infections, alters animal immunity. High population density is empirically considered to induce prophylactic immunity to reduce the infection risk, which was challenged by a model of low connectivity between infectious and susceptible individuals in crowded animals. The migratory locust, which exhibits polyphenism through gregarious and solitary phases in response to population density and displays different resistance to fungal biopesticide (Metarhizium anisopliae, was used to observe the prophylactic immunity of crowded animals. We applied an RNA-sequencing assay to investigate differential expression in fat body samples of gregarious and solitary locusts before and after infection. Solitary locusts devoted at least twice the number of genes for combating M. anisopliae infection than gregarious locusts. The transcription of immune molecules such as pattern recognition proteins, protease inhibitors, and anti-oxidation proteins, was increased in prophylactic immunity of gregarious locusts. The differentially expressed transcripts reducing gregarious locust susceptibility to M. anisopliae were confirmed at the transcriptional and translational level. Further investigation revealed that locust GNBP3 was susceptible to proteolysis while GNBP1, induced by M. anisopliae infection, resisted proteolysis. Silencing of gnbp3 by RNAi significantly shortened the life span of gregarious locusts but not solitary locusts. By contrast, gnbp1 silencing did not affect the life span of both gregarious and solitary locusts after M. anisopliae infection. Thus, the GNBP3-dependent immune responses were involved in the phenotypic resistance of gregarious locusts to fungal infection, but were redundant in solitary locusts. Our results indicated that gregarious locusts prophylactically activated upstream modulators of immune cascades rather than downstream effectors, preferring to quarantine rather than eliminate pathogens to

  2. Anomalous transport in the crowded world of biological cells.

    Science.gov (United States)

    Höfling, Felix; Franosch, Thomas

    2013-04-01

    A ubiquitous observation in cell biology is that the diffusive motion of macromolecules and organelles is anomalous, and a description simply based on the conventional diffusion equation with diffusion constants measured in dilute solution fails. This is commonly attributed to macromolecular crowding in the interior of cells and in cellular membranes, summarizing their densely packed and heterogeneous structures. The most familiar phenomenon is a sublinear, power-law increase of the mean-square displacement (MSD) as a function of the lag time, but there are other manifestations like strongly reduced and time-dependent diffusion coefficients, persistent correlations in time, non-Gaussian distributions of spatial displacements, heterogeneous diffusion and a fraction of immobile particles. After a general introduction to the statistical description of slow, anomalous transport, we summarize some widely used theoretical models: Gaussian models like fractional Brownian motion and Langevin equations for visco-elastic media, the continuous-time random walk model, and the Lorentz model describing obstructed transport in a heterogeneous environment. Particular emphasis is put on the spatio-temporal properties of the transport in terms of two-point correlation functions, dynamic scaling behaviour, and how the models are distinguished by their propagators even if the MSDs are identical. Then, we review the theory underlying commonly applied experimental techniques in the presence of anomalous transport like single-particle tracking, fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP). We report on the large body of recent experimental evidence for anomalous transport in crowded biological media: in cyto- and nucleoplasm as well as in cellular membranes, complemented by in vitro experiments where a variety of model systems mimic physiological crowding conditions. Finally, computer simulations are discussed which play an important

  3. Anomalous transport in the crowded world of biological cells

    Science.gov (United States)

    Höfling, Felix; Franosch, Thomas

    2013-04-01

    A ubiquitous observation in cell biology is that the diffusive motion of macromolecules and organelles is anomalous, and a description simply based on the conventional diffusion equation with diffusion constants measured in dilute solution fails. This is commonly attributed to macromolecular crowding in the interior of cells and in cellular membranes, summarizing their densely packed and heterogeneous structures. The most familiar phenomenon is a sublinear, power-law increase of the mean-square displacement (MSD) as a function of the lag time, but there are other manifestations like strongly reduced and time-dependent diffusion coefficients, persistent correlations in time, non-Gaussian distributions of spatial displacements, heterogeneous diffusion and a fraction of immobile particles. After a general introduction to the statistical description of slow, anomalous transport, we summarize some widely used theoretical models: Gaussian models like fractional Brownian motion and Langevin equations for visco-elastic media, the continuous-time random walk model, and the Lorentz model describing obstructed transport in a heterogeneous environment. Particular emphasis is put on the spatio-temporal properties of the transport in terms of two-point correlation functions, dynamic scaling behaviour, and how the models are distinguished by their propagators even if the MSDs are identical. Then, we review the theory underlying commonly applied experimental techniques in the presence of anomalous transport like single-particle tracking, fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP). We report on the large body of recent experimental evidence for anomalous transport in crowded biological media: in cyto- and nucleoplasm as well as in cellular membranes, complemented by in vitro experiments where a variety of model systems mimic physiological crowding conditions. Finally, computer simulations are discussed which play an important

  4. Crowds As Complex Adaptive Systems: Strategic Implications For Law Enforcement

    Science.gov (United States)

    2016-03-01

    attention on the police. Celebratory chants had changed to “Please don’t shoot us!”—a reference to the death of Victoria Snellgrove—and “ Hell no, we...of groups chanting team slogans and slogans indicative of defiance against police attempts at controlling the crowd. “Please don’t shoot us!,” “ Hell ...Defense for the Modern Protester.” It provides advice on mass movements of people and the use of tools such as physical barriers and protective clothing

  5. Charisma, crowd psychology and altered states of consciousness.

    Science.gov (United States)

    Lindholm, C

    1992-09-01

    This paper argues that an interpretive meaning-centered analysis is not adequate for understanding collective behavior that is outside the range of calculating rationality. Alternative approaches to collective irrational action are drawn from the work of Weber and Durkheim, as well as from the crowd psychologists Le Bon and Tarde. These approaches are then illustrated in a short analysis of the trajectories and recruitment techniques of two contemporary American religious annunications: est and Scientology, and the findings applied to the general social formation.

  6. Class I malocclusion with anterior crossbite and severe crowding

    Directory of Open Access Journals (Sweden)

    Daltro Enéas Ritter

    2014-04-01

    Full Text Available This article reports the orthodontic diagnosis and treatment planning carried out with a 14-year and 5-month-old female patient with esthetic and functional complaints. She presented an Angle Class I malocclusion, anterior crossbite and severe crowding in both maxillary and mandibular arches, in addition to a lightly concave straight facial profile. Orthodontic treatment did not require extraction. Crossbite was corrected by protrusion of upper teeth, which contributed to alignment and leveling of teeth, in addition to improving the patient's facial profile. The case was presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO as a requirement for the BBO certification.

  7. An Improved Convolutional Neural Network on Crowd Density Estimation

    Directory of Open Access Journals (Sweden)

    Pan Shao-Yun

    2016-01-01

    Full Text Available In this paper, a new method is proposed for crowd density estimation. An improved convolutional neural network is combined with traditional texture feature. The data calculated by the convolutional layer can be treated as a new kind of features.So more useful information of images can be extracted by different features.In the meantime, the size of image has little effect on the result of convolutional neural network. Experimental results indicate that our scheme has adequate performance to allow for its use in real world applications.

  8. Some Numerical Aspects on Crowd Motion - The Hughes Model

    KAUST Repository

    Gomes, Diogo A.

    2016-01-06

    Here, we study a crowd model proposed by R. Hughes in [5] and we describe a numerical approach to solve it. This model comprises a Fokker-Planck equation coupled with an Eikonal equation with Dirichlet or Neumann data. First, we establish a priori estimates for the solution. Second, we study radial solutions and identify a shock formation mechanism. Third, we illustrate the existence of congestion, the breakdown of the model, and the trend to the equilibrium. Finally, we propose a new numerical method and consider two numerical examples.

  9. Collective learning dynamics in behavioral crowds. Comment on "Human behaviours in evacuation crowd dynamics: From modeling to "big data" toward crisis management" by Nicola Bellomo et al.

    Science.gov (United States)

    Burini, D.

    2016-09-01

    A recent literature on crowd dynamics [9,10] has enlightened that the management of crisis situations needs models able to depict social behaviors and, in particular, the spread of emotional feelings such as stress by panic situation.

  10. Crowd behaviour during high-stress evacuations in an immersive virtual environment.

    Science.gov (United States)

    Moussaïd, Mehdi; Kapadia, Mubbasir; Thrash, Tyler; Sumner, Robert W; Gross, Markus; Helbing, Dirk; Hölscher, Christoph

    2016-09-01

    Understanding the collective dynamics of crowd movements during stressful emergency situations is central to reducing the risk of deadly crowd disasters. Yet, their systematic experimental study remains a challenging open problem due to ethical and methodological constraints. In this paper, we demonstrate the viability of shared three-dimensional virtual environments as an experimental platform for conducting crowd experiments with real people. In particular, we show that crowds of real human subjects moving and interacting in an immersive three-dimensional virtual environment exhibit typical patterns of real crowds as observed in real-life crowded situations. These include the manifestation of social conventions and the emergence of self-organized patterns during egress scenarios. High-stress evacuation experiments conducted in this virtual environment reveal movements characterized by mass herding and dangerous overcrowding as they occur in crowd disasters. We describe the behavioural mechanisms at play under such extreme conditions and identify critical zones where overcrowding may occur. Furthermore, we show that herding spontaneously emerges from a density effect without the need to assume an increase of the individual tendency to imitate peers. Our experiments reveal the promise of immersive virtual environments as an ethical, cost-efficient, yet accurate platform for exploring crowd behaviour in high-risk situations with real human subjects. © 2016 The Authors.

  11. [Etiological problems of anterior tooth crowding: the role of the third molar].

    Science.gov (United States)

    Minervini, G; Posillico, N

    1990-01-01

    The authors discussed about the extraction or not of the 3 degrees molar either to prevent or correct the dental crowding. They state that, since there is no definitive evidence of the real importance of the 3 degrees molar in creating dental crowding, it is not possible to perform without discrimination 3 degrees molar germectomy nor the extraction for prevention.

  12. From water and ions to crowded biomacromolecules: in vivo structuring of a prokaryotic cell.

    Science.gov (United States)

    Spitzer, Jan

    2011-09-01

    The interactions and processes which structure prokaryotic cytoplasm (water, ions, metabolites, and biomacromolecules) and ensure the fidelity of the cell cycle are reviewed from a physicochemical perspective. Recent spectroscopic and biological evidence shows that water has no active structuring role in the cytoplasm, an unnecessary notion still entertained in the literature; water acts only as a normal solvent and biochemical reactant. Subcellular structuring arises from localizations and interactions of biomacromolecules and from the growth and modifications of their surfaces by catalytic reactions. Biomacromolecular crowding is a fundamental physicochemical characteristic of cells in vivo. Though some biochemical and physiological effects of crowding (excluded volume effect) have been documented, crowding assays with polyglycols, dextrans, etc., do not properly mimic the compositional variety of biomacromolecules in vivo. In vitro crowding assays are now being designed with proteins, which better reflect biomacromolecular environments in vivo, allowing for hydrophobic bonding and screened electrostatic interactions. I elaborate further the concept of complex vectorial biochemistry, where crowded biomacromolecules structure the cytosol into electrolyte pathways and nanopools that electrochemically "wire" the cell. Noncovalent attractions between biomacromolecules transiently supercrowd biomacromolecules into vectorial, semiconducting multiplexes with a high (35 to 95%)-volume fraction of biomacromolecules; consequently, reservoirs of less crowded cytosol appear in order to maintain the experimental average crowding of ∼25% volume fraction. This nonuniform crowding model allows for fast diffusion of biomacromolecules in the uncrowded cytosolic reservoirs, while the supercrowded vectorial multiplexes conserve the remarkable repeatability of the cell cycle by preventing confusing cross talk of concurrent biochemical reactions.

  13. Stability analysis of predator-prey interaction with a crowding effect ...

    African Journals Online (AJOL)

    The mathematical modeling of species interactions usually relies on competition models. However, it is known that species interactions may exhibit more complicated patterns with a crowding effect and this can be particularly important in benign environments. In this paper we discuss competition models with a crowding ...

  14. Effect of experience, expectation and resource availability on perceptions of crowding among trout anglers in Pennsylvania

    Science.gov (United States)

    Craig A. Miller

    1995-01-01

    Crowding research has suggested expectancy theory as one explanation to perceptions of crowding expressed by participants in outdoor recreation activities. Expectancy theory states that an individual enters into an activity with a preconceived set of expectations for the outcome of the experience. In this study, anglers fishing on the opening day of Pennsylvania's...

  15. Do wisdom teeth induce lower anterior teeth crowding? A systematic literature review.

    Science.gov (United States)

    Stanaitytė, Rūta; Trakinienė, Giedrė; Gervickas, Albinas

    2014-01-01

    Individuals with dental crowding are the most frequent patients in the orthodontic practice.The purpose of this article is to find out if the lower third molars are the main reason of crowding in the lower dental arch. As well to find out other factors which can influence the lower incisors crowding. The aim was to identify studies and reviews related to the effect of the lower third molars on the lower dental arch crowding. A literature survey was performed using Medline database. Used key words were lower third molar, influence of wisdom teeth, wisdom teeth and anterior crowding, lower dental arch changes. The articles from 1971 to 2011 related to topic were identified. Selected articles were published in dental journals in English. Full texts of the selected articles were analyzed. Articles about the dental crowding after orthodontic treatment were not included. All studies accomplished with human participants. It was found 223 articles but only 21 articles corresponded to selected criteria and were analyzed. This review is based on the investigations of 12 laboratory researchers, 4 clinical researches, 2 questionnaires and 3 literature reviews. The results are quite contradictory: some authors support the opinion that lower third molars cause teeth crowding, the others confirm conversy. Exist other factors affecting the mandibular incisors crowding: dental (teeth crown size, dental arch length loss, poor periodontal status and primary teeth loss), skeletal (growth of the jaws and malocclusion) and general (age and gender).

  16. Effects of crowd size on referee decisions: analysis of the FA Cup.

    Science.gov (United States)

    Downward, Paul; Jones, Marc

    2007-12-01

    Data were collected on the number of first yellow cards awarded during 857 games, over six seasons (1996 - 2002), played in the Football Association (FA) Cup. Overall, a significantly higher number of yellow cards were awarded against the away team, while a non-linear relationship between crowd size and yellow cards was observed. In general, the probability of a yellow card being awarded against the home team decreased as crowd size increased, but was attenuated for the largest crowd sizes. Crowd size may be related to the probability of the home team receiving a yellow card in two potential ways. Crowd noise may be a decision-making heuristic whereby the likelihood that an incident is a foul is increased when accompanied by crowd noise. Alternatively, referees may seek to appease the crowd and are more likely to do so as crowd size increases. The present findings have implications for the training of match officials and for coaches and players as they prepare to play away from home.

  17. Kinetic models for crowd dynamics. Comment on "Human behaviours in evacuation crowd dynamics: From modelling to "big data" toward crisis management" by N. Bellomo et al.

    Science.gov (United States)

    Banasiak, J.

    2016-09-01

    There has been a hierarchy of models of crowd behaviour. One can consider the crowd at the so called microscopic level, as a collection of individuals, and derive its description in the form of a (large) system of ordinary differential equations describing the position and velocity of each individual, in parallel to the Newton's description of matter, see e.g. [10]. Another possibility is to describe crowd, in analogy to fluid dynamics, by providing its density and velocity at a given point, see e.g. [11,12]. At the same time, it is recognized that crowd is 'living, social' system that is prone to exhibit rare, not easily predictable, behaviour in response to stress induced by the perception of danger, or of the action of specific agents, see e.g. [1,2]. This high probability of the occurrence of events that are far from average, makes the crowd behaviour similar to the processes with fat-tailed distribution of events. Such unlikely events have been metaphorically termed black swans in [14], or Lévy flights in [13]. While microscopic and macroscopic models can capture many features of crowd dynamics, including obstacles, see [3,8], such models are described by differential equations that inherently are local in space. At the same time, black swan events are often caused by non-local interactions such as self-organization, learning or adherence to some averaged group behaviour. It is known that such interactions are well described by mean field models best represented by integro-differential equations, such as the Boltzmann equation of the rarefied gas theory. This has made plausible to introduce crowd models at the intermediate, (meso) scale by describing the crowd by the one particle distribution function that gives the density of individuals at any particular state; that is, at a given point in the domain and moving with a specific velocity.

  18. The increasing unemployment gap between the low and high educated in West Germany. Structural or cyclical crowding-out?

    Science.gov (United States)

    Klein, Markus

    2015-03-01

    This paper addresses trends in education-specific unemployment risks at labor market entry in West Germany from the mid-1970s to the present. In line with previous research it shows that vocationally qualified school-leavers have relatively lower unemployment risks than school-leavers with general education. Over time, the gap in unemployment risks between the low-educated and medium- and highly educated labor market entrants substantially widened for both sexes. The literature identifies two different mechanisms for this trend: structural or cyclical crowding out. While in the former scenario low-educated become increasingly unemployed due to an oversupply of tertiary graduates and displacement from above, in the latter their relative unemployment risk varies with the business cycle. The results provide evidence for cyclical rather than structural crowding-out in West Germany. Since macroeconomic conditions became generally worse over time, this strongly explains the widening unemployment gap between the low-educated and all other education groups. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Track-based event recognition in a realistic crowded environment

    Science.gov (United States)

    van Huis, Jasper R.; Bouma, Henri; Baan, Jan; Burghouts, Gertjan J.; Eendebak, Pieter T.; den Hollander, Richard J. M.; Dijk, Judith; van Rest, Jeroen H.

    2014-10-01

    Automatic detection of abnormal behavior in CCTV cameras is important to improve the security in crowded environments, such as shopping malls, airports and railway stations. This behavior can be characterized at different time scales, e.g., by small-scale subtle and obvious actions or by large-scale walking patterns and interactions between people. For example, pickpocketing can be recognized by the actual snatch (small scale), when he follows the victim, or when he interacts with an accomplice before and after the incident (longer time scale). This paper focusses on event recognition by detecting large-scale track-based patterns. Our event recognition method consists of several steps: pedestrian detection, object tracking, track-based feature computation and rule-based event classification. In the experiment, we focused on single track actions (walk, run, loiter, stop, turn) and track interactions (pass, meet, merge, split). The experiment includes a controlled setup, where 10 actors perform these actions. The method is also applied to all tracks that are generated in a crowded shopping mall in a selected time frame. The results show that most of the actions can be detected reliably (on average 90%) at a low false positive rate (1.1%), and that the interactions obtain lower detection rates (70% at 0.3% FP). This method may become one of the components that assists operators to find threatening behavior and enrich the selection of videos that are to be observed.

  20. Network dynamics of social influence in the wisdom of crowds.

    Science.gov (United States)

    Becker, Joshua; Brackbill, Devon; Centola, Damon

    2017-06-27

    A longstanding problem in the social, biological, and computational sciences is to determine how groups of distributed individuals can form intelligent collective judgments. Since Galton's discovery of the "wisdom of crowds" [Galton F (1907) Nature 75:450-451], theories of collective intelligence have suggested that the accuracy of group judgments requires individuals to be either independent, with uncorrelated beliefs, or diverse, with negatively correlated beliefs [Page S (2008) The Difference: How the Power of Diversity Creates Better Groups, Firms, Schools, and Societies]. Previous experimental studies have supported this view by arguing that social influence undermines the wisdom of crowds. These results showed that individuals' estimates became more similar when subjects observed each other's beliefs, thereby reducing diversity without a corresponding increase in group accuracy [Lorenz J, Rauhut H, Schweitzer F, Helbing D (2011) Proc Natl Acad Sci USA 108:9020-9025]. By contrast, we show general network conditions under which social influence improves the accuracy of group estimates, even as individual beliefs become more similar. We present theoretical predictions and experimental results showing that, in decentralized communication networks, group estimates become reliably more accurate as a result of information exchange. We further show that the dynamics of group accuracy change with network structure. In centralized networks, where the influence of central individuals dominates the collective estimation process, group estimates become more likely to increase in error.

  1. Secure Nearest Neighbor Query on Crowd-Sensing Data

    Directory of Open Access Journals (Sweden)

    Ke Cheng

    2016-09-01

    Full Text Available Nearest neighbor queries are fundamental in location-based services, and secure nearest neighbor queries mainly focus on how to securely and quickly retrieve the nearest neighbor in the outsourced cloud server. However, the previous big data system structure has changed because of the crowd-sensing data. On the one hand, sensing data terminals as the data owner are numerous and mistrustful, while, on the other hand, in most cases, the terminals find it difficult to finish many safety operation due to computation and storage capability constraints. In light of they Multi Owners and Multi Users (MOMU situation in the crowd-sensing data cloud environment, this paper presents a secure nearest neighbor query scheme based on the proxy server architecture, which is constructed by protocols of secure two-party computation and secure Voronoi diagram algorithm. It not only preserves the data confidentiality and query privacy but also effectively resists the collusion between the cloud server and the data owners or users. Finally, extensive theoretical and experimental evaluations are presented to show that our proposed scheme achieves a superior balance between the security and query performance compared to other schemes.

  2. Secure Nearest Neighbor Query on Crowd-Sensing Data.

    Science.gov (United States)

    Cheng, Ke; Wang, Liangmin; Zhong, Hong

    2016-09-22

    Nearest neighbor queries are fundamental in location-based services, and secure nearest neighbor queries mainly focus on how to securely and quickly retrieve the nearest neighbor in the outsourced cloud server. However, the previous big data system structure has changed because of the crowd-sensing data. On the one hand, sensing data terminals as the data owner are numerous and mistrustful, while, on the other hand, in most cases, the terminals find it difficult to finish many safety operation due to computation and storage capability constraints. In light of they Multi Owners and Multi Users (MOMU) situation in the crowd-sensing data cloud environment, this paper presents a secure nearest neighbor query scheme based on the proxy server architecture, which is constructed by protocols of secure two-party computation and secure Voronoi diagram algorithm. It not only preserves the data confidentiality and query privacy but also effectively resists the collusion between the cloud server and the data owners or users. Finally, extensive theoretical and experimental evaluations are presented to show that our proposed scheme achieves a superior balance between the security and query performance compared to other schemes.

  3. LESSONS LEARNED ABOUT PUBLIC HEALTH FROM ONLINE CROWD SURVEILLANCE.

    Science.gov (United States)

    Hill, Shawndra; Merchant, Raina; Ungar, Lyle

    2013-09-10

    The Internet has forever changed the way people access information and make decisions about their healthcare needs. Patients now share information about their health at unprecedented rates on social networking sites such as Twitter and Facebook and on medical discussion boards. In addition to explicitly shared information about health conditions through posts, patients reveal data on their inner fears and desires about health when searching for health-related keywords on search engines. Data are also generated by the use of mobile phone applications that track users' health behaviors (e.g., eating and exercise habits) as well as give medical advice. The data generated through these applications are mined and repackaged by surveillance systems developed by academics, companies, and governments alike to provide insight to patients and healthcare providers for medical decisions. Until recently, most Internet research in public health has been surveillance focused or monitoring health behaviors. Only recently have researchers used and interacted with the crowd to ask questions and collect health-related data. In the future, we expect to move from this surveillance focus to the "ideal" of Internet-based patient-level interventions where healthcare providers help patients change their health behaviors. In this article, we highlight the results of our prior research on crowd surveillance and make suggestions for the future.

  4. A Perturbed Compressed Sensing Protocol for Crowd Sensing

    Directory of Open Access Journals (Sweden)

    Zijian Zhang

    2016-01-01

    Full Text Available Crowd sensing network is a data-centric network consisting of many participants uploading environmental data by smart mobile devices or predeployed sensors; however, concerns about communication complexity and data confidentiality arise in real application. Recently, Compressed Sensing (CS is a booming theory which employs nonadaptive linear projections to reduce data quantity and then reconstructs the original signal. Unfortunately, privacy issues induced by untrusted network still remain to be unsettled practically. In this paper, we consider crowd sensing using CS in wireless sensor network (WSN as the application scenario and propose a data collection protocol called perturbed compressed sensing protocol (PCSP to preserve data confidentiality as well as its practicality. At first, we briefly introduce the CS theory and three factors correlated with reconstruction effect. Secondly, a secure CS-based framework using a secret disturbance is developed to protect raw data in WSN, in which each node collects, encrypts, measures, and transmits the sampled data in our protocol. Formally, we prove that our protocol is CPA-secure on the basis of a theorem. Finally, evaluation on real and simulative datasets shows that our protocol could not only achieve higher efficiency than related algorithms but also protect signal’s confidentiality.

  5. Effect of pattern complexity on the visual span for Chinese and alphabet characters.

    Science.gov (United States)

    Wang, Hui; He, Xuanzi; Legge, Gordon E

    2014-07-03

    The visual span for reading is the number of letters that can be recognized without moving the eyes and is hypothesized to impose a sensory limitation on reading speed. Factors affecting the size of the visual span have been studied using alphabet letters. There may be common constraints applying to recognition of other scripts. The aim of this study was to extend the concept of the visual span to Chinese characters and to examine the effect of the greater complexity of these characters. We measured visual spans for Chinese characters and alphabet letters in the central vision of bilingual subjects. Perimetric complexity was used as a metric to quantify the pattern complexity of binary character images. The visual span tests were conducted with four sets of stimuli differing in complexity--lowercase alphabet letters and three groups of Chinese characters. We found that the size of visual spans decreased with increasing complexity, ranging from 10.5 characters for alphabet letters to 4.5 characters for the most complex Chinese characters studied. A decomposition analysis revealed that crowding was the dominant factor limiting the size of the visual span, and the amount of crowding increased with complexity. Errors in the spatial arrangement of characters (mislocations) had a secondary effect. We conclude that pattern complexity has a major effect on the size of the visual span, mediated in large part by crowding. Measuring the visual span for Chinese characters is likely to have high relevance to understanding visual constraints on Chinese reading performance. © 2014 ARVO.

  6. A research agenda to assure equity during periods of emergency department crowding.

    Science.gov (United States)

    Hwang, Ula; Weber, Ellen J; Richardson, Lynne D; Sweet, Vicki; Todd, Knox; Abraham, Gallane; Ankel, Felix

    2011-12-01

    The effect of emergency department (ED) crowding on equitable care is the least studied of the domains of quality as defined by the Institute of Medicine (IOM). Inequities in access and treatment throughout the health care system are well documented in all fields of medicine. While there is little evidence demonstrating that inequity is worsened by crowding, theory and evidence from social science disciplines, as well as known barriers to care for vulnerable populations, would suggest that crowding will worsen inequities. To design successful interventions, however, it is important to first understand how crowding can result in disparities and base interventions on these mechanisms. A research agenda is proposed to understand mechanisms that may threaten equity during periods of crowding and design and test potential interventions that may ensure the equitable aspect of quality of care. © 2011 by the Society for Academic Emergency Medicine.

  7. Biochemical reactions in crowded environments: Revisiting the effects of volume exclusion with simulations

    Directory of Open Access Journals (Sweden)

    David eGomez

    2015-06-01

    Full Text Available Molecular crowding is ubiquitous within cells and affects many biological processes including protein-protein binding, enzyme activities and gene regulation. Here we revisit some generic effects of crowding using a combination of lattice simulations and reaction-diffusion simulations with the program ReaDDy. Specifically, we implement three reactions, simple binding, a diffusion-limited reaction and a reaction with Michaelis-Menten kinetics. Histograms of binding and unbinding times provide a detailed picture how crowding affects these reactions and how the separate effects of crowding on binding equilibrium and on diffusion act together. In addition, we discuss how crowding affects processes related to gene expression such as RNA polymerase-promoter binding and translation elongation.

  8. Research on the Behavior Characteristics of Pedestrian Crowd Weaving Flow in Transport Terminal

    Directory of Open Access Journals (Sweden)

    Liya Yao

    2012-01-01

    Full Text Available Due to the poor transfer organization in urban public transport terminal, pedestrian crowd are often forced to weaving in their transfer flow lines. Frequent weaving behaviors not only decrease passengers’ transfer comfort, but may also trigger serious crowd disaster such as trampling. In order to get accurate understanding of the weaving features of pedestrian crowd and analyze the relevant evolution law, researches have been conducted on the basis of field investigation. First, the typical weaving phenomenon were defined and classified, and a microscopic parameters system of pedestrian crowd weaving flow was constructed. The detection and quantification methods of multiple indicator parameters were also given. Then, correlation between different behavioral parameters was analyzed based on the survey data of weaving pedestrian crowd on the stairs of DongZhiMen (DZM hub. The basic characteristics and evolution law of the weaving behaviors were then discussed, and conclusions were drawn.

  9. Investigating frequency of front teeth crowding at elementary school children ages 7-14 from Niš and surroundings

    Directory of Open Access Journals (Sweden)

    Aničić-Ristić Bojana

    2013-01-01

    Full Text Available Dental crowding can be defined as a lack of space in dental arch for the proper placement of all teeth. The aim of this study was to determine prevalence of maxillary and mandibular anterior crowding at school children from Niš and surroundings. Material and methods: The study sample comprised 2027 elementary school children (1025girls, 1002 boys. We have analyzed the presence and extent of maxillary and mandibular anterior crowding (mild, moderate and severe . Results: The percentage of maxillary anterior crowding for girls (73,55% was greater than that for boys (65,65%. The most common was a mild crowding (37,58% girls, 42,35% boys, then moderate crowding (35,28% girls, 35,22% boys and the lowest percentage had severe crowding (27,14% girls, 22,43% boys.The percentage of mandibular anterior crowding for girls (78,54% was greater than that for boys (76,55%. The most common was a mild crowding (40,37% girls, 39,95% boys, then moderate crowding (33,78% girls, 36,25% boys and the lowest percentage had severe crowding (25,84% girls, 23,85% boys. Conclusion: It is important to have knowledge about the incidence of dental crowding in school children, that we can start with treatment on time.

  10. Finding The Most Important Actor in Online Crowd by Social Network Analysis

    Science.gov (United States)

    Yuliana, I.; Santosa, P. I.; Setiawan, N. A.; Sukirman

    2017-02-01

    Billion of people create trillions of connections through social media every single day. The increasing use of social media has led to dramatic changes in the of way science, government, healthcare, entertainment and enterprise operate. Large-scale participation in Technology-Mediated Social Participation (TMSP) system has opened up incredible new opportunities to deploy online crowd. This descriptive-correlational research used social network analysis (SNA) on data gathered from Fanpage Facebook of Greenpeace Indonesia related to important critical issues, the bushfires in 2015. SNA identifies relations on each member by sociometrics parameter such as three centrality (degree, closeness and betweenesse) for measuring and finding the most important actor in the online community. This paper use Fruchterman Rein-gold algorithm to visualize the online community in a graph, while Clauset-Newman-Moore is a technique to identify groups in community. As the result found 3735 vertices related to actors, 6927 edges as relation, 14 main actors in size order and 22 groups in Greenpeace Indonesia online community. This research contributes to organize some information for Greenpeace Indonesia managing their potency in online community to identify human behaviour.

  11. Dynamic detection of abnormalities in video analysis of crowd behavior with DBSCAN and neural networks

    Directory of Open Access Journals (Sweden)

    Hocine Chebi

    2016-10-01

    Full Text Available Visual analysis of human behavior is a broad field within computer vision. In this field of work, we are interested in dynamic methods in the analysis of crowd behavior which consist in detecting the abnormal entities in a group in a dense scene. These scenes are characterized by the presence of a great number of people in the camera’s field of vision. The major problem is the development of an autonomous approach for the management of a great number of anomalies which is almost impossible to carry out by human operators. We present in this paper a new approach for the detection of dynamic anomalies of very dense scenes measuring the speed of both the individuals and the whole group. The various anomalies are detected by dynamically switching between two approaches: An artificial neural network (ANN for the management of group anomalies of people, and a Density-Based Spatial Clustering of Application with Noise (DBSCAN in the case of entities. For greater robustness and effectiveness, we introduced two routines that serve to eliminate the shades and the management of occlusions. The two latter phases have proven that the results of the simulation are comparable to existing work.

  12. Visual Impairment

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Visual Impairment KidsHealth / For Teens / Visual Impairment What's in ... with the brain, making vision impossible. What Is Visual Impairment? Many people have some type of visual ...

  13. Visual field

    Science.gov (United States)

    Perimetry; Tangent screen exam; Automated perimetry exam; Goldmann visual field exam; Humphrey visual field exam ... Confrontation visual field exam. This is a quick and basic check of the visual field. The health care provider ...

  14. Fluorescence Dynamics of a FRET Probe Designed for Crowding Studies.

    Science.gov (United States)

    Currie, Megan; Leopold, Hannah; Schwarz, Jacob; Boersma, Arnold J; Sheets, Erin D; Heikal, Ahmed A

    2017-06-15

    Living cells are crowded with macromolecules and organelles. As a result, there is an urgent need for molecular sensors for quantitative, site-specific assessment of the macromolecular crowding effects on a myriad of biochemical processes toward quantitative cell biology and biophysics. Here we investigate the excited-state dynamics and translational diffusion of a novel FRET sensor (mCerulean-linker-mCitrine) in a buffer (PBS, pH 7.4) at room temperature. Complementary experiments were carried out on free CFP, YFP, and the cleaved FRET probe as controls. The wavelength-dependent fluorescence lifetime measurements of the donor and acceptor in the FRET probe, using the time-correlated single-photon counting technique, indicate an energy transfer efficiency of 6.8 ± 0.9% in PBS, with distinct excited-state dynamics from the recombinant CFP and YFP. The estimated mCerulean-mCitrine distance in this FRET probe is 7.7 ± 0.2 nm. The energy transfer efficiency increases (11.5 ± 0.9%) as the concentration of Ficoll-70 increases over the range of 0-300 g/L with an estimated mCerulean-mCitrine distance of 6.1 ± 0.2 nm. Complementary time-resolved anisotropy measurements suggest that the rotational diffusion of hetero-FRET in PBS is sensitive to the energy transfer from the donor to the acceptor. The results also suggest that the linker, -(GSG)6A(EAAAK)6A(GSG)6A(EAAAK)6A(GSG)6-, is rather flexible, and the observed rotational dynamics is likely to be due to a segmental mobility of the FRET pairs rather than an overall tumbling motion of a rigid probe. Comparative studies on a new construct of a FRET probe with a shorter, more flexible linker, mCerulean-(GSG)18-mCitrine, reveal enhanced energy transfer efficiency. On the millisecond time scale, fluorescence fluctuation analyses of the acceptor (excited at 488 nm) provide a means to examine the translational diffusion coefficient of the FRET probe. The results also suggest that the linker is flexible in this FRET probe, and

  15. Macromolecular crowding for tailoring tissue-derived fibrillated matrices.

    Science.gov (United States)

    Magno, Valentina; Friedrichs, Jens; Weber, Heather M; Prewitz, Marina C; Tsurkan, Mikhail V; Werner, Carsten

    2017-06-01

    Tissue-derived fibrillated matrices can be instrumental for the in vitro reconstitution of multiphasic extracellular microenvironments. However, despite of several advantages, the obtained scaffolds so far offer a rather narrow range of materials characteristics only. In this work, we demonstrate how macromolecular crowding (MMC) - the supplementation of matrix reconstitution media with synthetic or natural macromolecules in ways to create excluded volume effects (EVE) - can be employed for tailoring important structural and biophysical characteristics of kidney-derived fibrillated matrices. Porcine kidneys were decellularized, ground and the obtained extracellular matrix (ECM) preparations were reconstituted under varied MMC conditions. We show that MMC strongly influences the fibrillogenesis kinetics and impacts the architecture and the elastic modulus of the reconstituted matrices, with diameters and relative alignment of fibrils increasing at elevated concentrations of the crowding agent Ficoll400, a nonionic synthetic polymer of sucrose. Furthermore, we demonstrate how MMC modulates the distribution of key ECM molecules within the reconstituted matrix scaffolds. As a proof of concept, we compared different variants of kidney-derived fibrillated matrices in cell culture experiments referring to specific requirements of kidney tissue engineering approaches. The results revealed that MMC-tailored matrices support the morphogenesis of human umbilical vein endothelial cells (HUVECs) into capillary networks and of murine kidney stem cells (KSCs) into highly branched aggregates. The established methodology is concluded to provide generally applicable new options for tailoring tissue-specific multiphasic matrices in vitro. Tissue-derived fibrillated matrices can be instrumental for the in vitro reconstitution of multiphasic extracellular microenvironments. However, despite of several advantages, the obtained scaffolds so far offer a rather narrow range of materials

  16. The curious anomaly of skewed judgment distributions and systematic error in the wisdom of crowds.

    Directory of Open Access Journals (Sweden)

    Ulrik W Nash

    Full Text Available Judgment distributions are often skewed and we know little about why. This paper explains the phenomenon of skewed judgment distributions by introducing the augmented quincunx (AQ model of sequential and probabilistic cue categorization by neurons of judges. In the process of developing inferences about true values, when neurons categorize cues better than chance, and when the particular true value is extreme compared to what is typical and anchored upon, then populations of judges form skewed judgment distributions with high probability. Moreover, the collective error made by these people can be inferred from how skewed their judgment distributions are, and in what direction they tilt. This implies not just that judgment distributions are shaped by cues, but that judgment distributions are cues themselves for the wisdom of crowds. The AQ model also predicts that judgment variance correlates positively with collective error, thereby challenging what is commonly believed about how diversity and collective intelligence relate. Data from 3053 judgment surveys about US macroeconomic variables obtained from the Federal Reserve Bank of Philadelphia and the Wall Street Journal provide strong support, and implications are discussed with reference to three central ideas on collective intelligence, these being Galton's conjecture on the distribution of judgments, Muth's rational expectations hypothesis, and Page's diversity prediction theorem.

  17. The curious anomaly of skewed judgment distributions and systematic error in the wisdom of crowds.

    Science.gov (United States)

    Nash, Ulrik W

    2014-01-01

    Judgment distributions are often skewed and we know little about why. This paper explains the phenomenon of skewed judgment distributions by introducing the augmented quincunx (AQ) model of sequential and probabilistic cue categorization by neurons of judges. In the process of developing inferences about true values, when neurons categorize cues better than chance, and when the particular true value is extreme compared to what is typical and anchored upon, then populations of judges form skewed judgment distributions with high probability. Moreover, the collective error made by these people can be inferred from how skewed their judgment distributions are, and in what direction they tilt. This implies not just that judgment distributions are shaped by cues, but that judgment distributions are cues themselves for the wisdom of crowds. The AQ model also predicts that judgment variance correlates positively with collective error, thereby challenging what is commonly believed about how diversity and collective intelligence relate. Data from 3053 judgment surveys about US macroeconomic variables obtained from the Federal Reserve Bank of Philadelphia and the Wall Street Journal provide strong support, and implications are discussed with reference to three central ideas on collective intelligence, these being Galton's conjecture on the distribution of judgments, Muth's rational expectations hypothesis, and Page's diversity prediction theorem.

  18. WoCE: A framework for Clustering Ensemble by Exploiting the Wisdom of Crowds Theory.

    Science.gov (United States)

    Yousefnezhad, Muhammad; Huang, Sheng-Jun; Zhang, Daoqiang

    2017-01-04

    The wisdom of crowds (WOCs), as a theory in the social science, gets a new paradigm in computer science. The WOC theory explains that the aggregate decision made by a group is often better than those of its individual members if specific conditions are satisfied. This paper presents a novel framework for unsupervised and semisupervised cluster ensemble by exploiting the WOC theory. We employ four conditions in the WOC theory, i.e., diversity, independency, decentralization, and aggregation, to guide both constructing of individual clustering results and final combination for clustering ensemble. First, independency criterion, as a novel mapping system on the raw data set, removes the correlation between features on our proposed method. Then, decentralization as a novel mechanism generates high quality individual clustering results. Next, uniformity as a new diversity metric evaluates the generated clustering results. Further, weighted evidence accumulation clustering method is proposed for the final aggregation without using thresholding procedure. Experimental study on varied data sets demonstrates that the proposed approach achieves superior performance to state-of-the-art methods.

  19. The walking behaviour of pedestrian social groups and its impact on crowd dynamics.

    Directory of Open Access Journals (Sweden)

    Mehdi Moussaïd

    Full Text Available Human crowd motion is mainly driven by self-organized processes based on local interactions among pedestrians. While most studies of crowd behaviour consider only interactions among isolated individuals, it turns out that up to 70% of people in a crowd are actually moving in groups, such as friends, couples, or families walking together. These groups constitute medium-scale aggregated structures and their impact on crowd dynamics is still largely unknown. In this work, we analyze the motion of approximately 1500 pedestrian groups under natural condition, and show that social interactions among group members generate typical group walking patterns that influence crowd dynamics. At low density, group members tend to walk side by side, forming a line perpendicular to the walking direction. As the density increases, however, the linear walking formation is bent forward, turning it into a V-like pattern. These spatial patterns can be well described by a model based on social communication between group members. We show that the V-like walking pattern facilitates social interactions within the group, but reduces the flow because of its "non-aerodynamic" shape. Therefore, when crowd density increases, the group organization results from a trade-off between walking faster and facilitating social exchange. These insights demonstrate that crowd dynamics is not only determined by physical constraints induced by other pedestrians and the environment, but also significantly by communicative, social interactions among individuals.

  20. An entropy model to measure heterogeneity of pedestrian crowds using self-propelled agents

    Science.gov (United States)

    Rangel-Huerta, A.; Ballinas-Hernández, A. L.; Muñoz-Meléndez, A.

    2017-05-01

    An entropy model to characterize the heterogeneity of a pedestrian crowd in a counter-flow corridor is presented. Pedestrians are modeled as self-propelled autonomous agents that are able to perform maneuvers to avoid collisions based on a set of simple rules of perception and action. An observer can determine a probability distribution function of the displayed behavior of pedestrians based only on external information. Three types of pedestrian are modeled, relaxed, standard and hurried pedestrians depending on their preferences of turn and non-turn when walking. Thus, using these types of pedestrians two crowds can be simulated: homogeneous and heterogeneous crowds. Heterogeneity is measured in this research based on the entropy in function of time. For that, the entropy of a homogeneous crowd comprising standard pedestrians is used as reference. A number of simulations to measure entropy of pedestrian crowds were conducted by varying different combinations of types of pedestrians, initial simulation conditions of macroscopic flow, as well as density of the crowd. Results from these simulations show that our entropy model is sensitive enough to capture the effect of both the initial simulation conditions about the spatial distribution of pedestrians in a corridor, and the composition of a crowd. Also, a relevant finding is that entropy in function of density presents a phase transition in the critical region.

  1. Routing in Dense Human Crowds Using Smartphone Movement Data and Optical Aerial Imagery

    Directory of Open Access Journals (Sweden)

    Florian Hillen

    2015-06-01

    Full Text Available In this paper, we propose a navigation approach for smartphones that enables visitors of major events to avoid crowded areas or narrow streets and to navigate out of dense crowds quickly. Two types of sensor data are integrated. Real-time optical images acquired and transmitted by an airborne camera system are used to compute an estimation of a crowd density map. For this purpose, a patch-based approach with a Gabor filter bank for texture classification in combination with an interest point detector and a smoothing function is applied. Furthermore, the crowd density is estimated based on location and movement speed of in situ smartphone measurements. This information allows for the enhancement of the overall crowd density layer. The composed density information is input to a least-cost routing workflow. Two possible use cases are presented, namely (i an emergency application and (ii a basic routing application. A prototypical implementation of the system is conducted as proof of concept. Our approach is capable of increasing the security level for major events. Visitors are able to avoid dense crowds by routing around them, while security and rescue forces are able to find the fastest way into the crowd.

  2. The influence of crowd density on the sound environment of commercial pedestrian streets.

    Science.gov (United States)

    Meng, Qi; Kang, Jian

    2015-04-01

    Commercial pedestrian streets are very common in China and Europe, with many situated in historic or cultural centres. The environments of these streets are important, including their sound environments. The objective of this study is to explore the relationships between the crowd density and the sound environments of commercial pedestrian streets. On-site measurements were performed at the case study site in Harbin, China, and a questionnaire was administered. The sound pressure measurements showed that the crowd density has an insignificant effect on sound pressure below 0.05 persons/m2, whereas when the crowd density is greater than 0.05 persons/m2, the sound pressure increases with crowd density. The sound sources were analysed, showing that several typical sound sources, such as traffic noise, can be masked by the sounds resulting from dense crowds. The acoustic analysis showed that crowd densities outside the range of 0.10 to 0.25 persons/m2 exhibited lower acoustic comfort evaluation scores. In terms of audiovisual characteristics, the subjective loudness increases with greater crowd density, while the acoustic comfort decreases. The results for an indoor underground shopping street are also presented for comparison. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Experimental study on small group behavior and crowd dynamics in a tall office building evacuation

    Science.gov (United States)

    Ma, Yaping; Li, Lihua; Zhang, Hui; Chen, Tao

    2017-05-01

    It is well known that a large percentage of occupants in a building are evacuated together with their friends, families, and officemates, especially in China. Small group behaviors are therefore critical for crowd movement. This paper aims to study the crowd dynamic considering different social relations and the impacts of small groups on crowd dynamics in emergency evacuation. Three experiments are conducted in an 11-storey office building. In the first two experiments, all participants are classmates and know each other well. They are evacuated as individuals or pairs. In the third experiment, social relations among the participants are complex. Participants consist of 8 families, 6 lovers and several individuals. Space-time features, speed characteristics and density-speed relations for each experiment are analyzed and compared. Results conclude that small group behaviors can make positive impacts on crowd dynamics when evacuees know each other and are cooperative. This conclusion is also testified by four verified experiments. In the third experiment, speeds of evacuees are lowest. Small groups form automatically with the presence of intimate social relations. Small groups in this experiment slow down the average speed of the crowd and make disturbance on the crowd flow. Small groups in this case make negative impacts on the movement of the crowd. It is because that evacuees do not know each other and they are competitive to each other. Characteristics of different types of small groups are also investigated. Experimental data can provide foundational parameters for evacuation model development and are helpful for building designers.

  4. The Walking Behaviour of Pedestrian Social Groups and Its Impact on Crowd Dynamics

    Science.gov (United States)

    Moussaïd, Mehdi; Perozo, Niriaska; Garnier, Simon; Helbing, Dirk; Theraulaz, Guy

    2010-01-01

    Human crowd motion is mainly driven by self-organized processes based on local interactions among pedestrians. While most studies of crowd behaviour consider only interactions among isolated individuals, it turns out that up to 70% of people in a crowd are actually moving in groups, such as friends, couples, or families walking together. These groups constitute medium-scale aggregated structures and their impact on crowd dynamics is still largely unknown. In this work, we analyze the motion of approximately 1500 pedestrian groups under natural condition, and show that social interactions among group members generate typical group walking patterns that influence crowd dynamics. At low density, group members tend to walk side by side, forming a line perpendicular to the walking direction. As the density increases, however, the linear walking formation is bent forward, turning it into a V-like pattern. These spatial patterns can be well described by a model based on social communication between group members. We show that the V-like walking pattern facilitates social interactions within the group, but reduces the flow because of its “non-aerodynamic” shape. Therefore, when crowd density increases, the group organization results from a trade-off between walking faster and facilitating social exchange. These insights demonstrate that crowd dynamics is not only determined by physical constraints induced by other pedestrians and the environment, but also significantly by communicative, social interactions among individuals. PMID:20383280

  5. Foule et public Crowd and audience. Reflections about the French theory of reception studies in the silent period

    Directory of Open Access Journals (Sweden)

    Emmanuel Plasseraud

    2012-04-01

    th century. It had many interpretations, which we can find again in cinema writtings. For those who fight against cinema, crowd can be seen as Gustave Le Bon describes it in its popularization of crowd psychology. Therefore, movie theaters are places where crowds relieve or excite their instincts. On the contrary, for film enthusiasts, cinema proposes a modern communal refoundation where crowds find back their lost spirituality. For them, theaters are places where an hypnotic phenomenon occurs, leading crowds. This conception is the foundation of the idea of « seventh art » invented by Canudo and used also, with diverses meanings, by Delluc, Gance, Epstein or L’Herbier. Is this conception suitable to the reality of the spectators practice at that time? Is it possible to consider the cinema audience as a whole, as it seems if we use the idea of crowd? We can answer no, and we can think that the gap between theory and reality of the film reception is one of the reasons explaining the problems of French cinema facing American cinema. The theorical deadlock of the French conception of film reception, due to the use of the notion of crowd, appears clearly in Germaine Dulac’s writtings. She was the first among French theoricians to doubt about the ability of cinema to get the crowds receiving Holy Communion. She understood that the audience, in its diversity, would dictate its tastes to the film-makers, expressing an idea that Hollywood producers had already assimilated.

  6. Learning Supervised Topic Models for Classification and Regression from Crowds.

    Science.gov (United States)

    Rodrigues, Filipe; Lourenco, Mariana; Ribeiro, Bernardete; Pereira, Francisco C

    2017-12-01

    The growing need to analyze large collections of documents has led to great developments in topic modeling. Since documents are frequently associated with other related variables, such as labels or ratings, much interest has been placed on supervised topic models. However, the nature of most annotation tasks, prone to ambiguity and noise, often with high volumes of documents, deem learning under a single-annotator assumption unrealistic or unpractical for most real-world applications. In this article, we propose two supervised topic models, one for classification and another for regression problems, which account for the heterogeneity and biases among different annotators that are encountered in practice when learning from crowds. We develop an efficient stochastic variational inference algorithm that is able to scale to very large datasets, and we empirically demonstrate the advantages of the proposed model over state-of-the-art approaches.

  7. Using Crowd Sensed Data as Input to Congestion Model

    DEFF Research Database (Denmark)

    Lehmann, Anders; Gross, Allan

    2016-01-01

    Emission of airborne pollutants and climate gasses from the transport sector is a growing problem, both in indus- trialised and developing countries. Planning of urban transport system is essential to minimise the environmental, health and economic impact of congestion in the transport system. To...... traffic systems, in less than an hour. The model is implemented in an open source database system, for easy interface with GIS resources and crowd sensed transportation data........ To get accurate and timely information on traffic congestion, and by extension information on air pollution, near real time traffic models are needed. We present in this paper an implementation of the Restricted Stochastic User equilibrium model, that is capable to model congestions for very large Urban...

  8. Mobile Crowd Sensing for Traffic Prediction in Internet of Vehicles.

    Science.gov (United States)

    Wan, Jiafu; Liu, Jianqi; Shao, Zehui; Vasilakos, Athanasios V; Imran, Muhammad; Zhou, Keliang

    2016-01-11

    The advances in wireless communication techniques, mobile cloud computing, automotive and intelligent terminal technology are driving the evolution of vehicle ad hoc networks into the Internet of Vehicles (IoV) paradigm. This leads to a change in the vehicle routing problem from a calculation based on static data towards real-time traffic prediction. In this paper, we first address the taxonomy of cloud-assisted IoV from the viewpoint of the service relationship between cloud computing and IoV. Then, we review the traditional traffic prediction approached used by both Vehicle to Infrastructure (V2I) and Vehicle to Vehicle (V2V) communications. On this basis, we propose a mobile crowd sensing technology to support the creation of dynamic route choices for drivers wishing to avoid congestion. Experiments were carried out to verify the proposed approaches. Finally, we discuss the outlook of reliable traffic prediction.

  9. THE OCCURRENCE OF SYNCHRONIZED JUMPING CROWD AT SPORTS STADIUMS

    Directory of Open Access Journals (Sweden)

    Martin Verner

    2017-11-01

    Full Text Available Since the age of the Rome Empire, people have been going for fun at the stadiums. Today, important reasons for visiting the stadium are sport games or cultural performances. The text is about occurrence of specific types of behaviour during sport games. The experiment was realized at four different sports stadiums and during three kinds of sports. The worst case of loads for the grandstand is the synchronized jumping of a crowd. This is type of behaviour, which can cause over limit vibration, visitors discomfort on the tribune, in the extreme case collapse of the grandstand. In any country today, the standards or references or math models are not for application of dynamic load to grandstand. Only the British standards are making recommendation how the designer should work with dynamic loads.

  10. Response Surface Analysis of Crowd Dynamics during Tawaf

    Science.gov (United States)

    Zarita, Zainuddin; Lim Eng, Aik

    2012-07-01

    A refined cellular automata model is applied to simulate the crowd movement of Muslim pilgrims performing the Tawaf ritual within the Al-Haram Mosque in Mecca. The results from the simulation are obtained and the influence of the predictor variables of the evacuation process (pedestrian flow and Tawaf duration) on the responses (pedestrian density, average walking speed, and cumulative evacuee) is investigated using response surface methodology (RSM). The average results from the experiments with an rms error less than 0.5 are obtained from the RSM. Its performance indicates that the RSM possesses excellent predictive ability for the model evacuation study, because both the experimental and the predicted values agree well with the results obtained in this study.

  11. Fast simulation of Brownian dynamics in a crowded environment.

    Science.gov (United States)

    Smith, Stephen; Grima, Ramon

    2017-01-14

    Brownian dynamics simulations are an increasingly popular tool for understanding spatially extended biochemical reaction systems. Recent improvements in our understanding of the cellular environment show that volume exclusion effects are fundamental to reaction networks inside cells. These systems are frequently studied by incorporating inert hard spheres (crowders) into three-dimensional Brownian dynamics (BD) simulations; however these methods are extremely slow owing to the sheer number of possible collisions between particles. Here we propose a rigorous "crowder-free" method to dramatically increase the simulation speed for crowded biochemical reaction systems by eliminating the need to explicitly simulate the crowders. We consider both the cases where the reactive particles are point particles, and where they themselves occupy a volume. Using simulations of simple chemical reaction networks, we show that the "crowder-free" method is up to three orders of magnitude faster than conventional BD and yet leads to nearly indistinguishable results from the latter.

  12. Principles of visual attention

    DEFF Research Database (Denmark)

    Bundesen, Claus; Habekost, Thomas

    The nature of attention is one of the oldest and most central problems in psychology. A huge amount of research has been produced on this subject in the last half century, especially on attention in the visual modality, but a general explanation has remained elusive. Many still view attention...... research as a field that is fundamentally fragmented. This book takes a different perspective and presents a unified theory of visual attention: the TVA model. The TVA model explains the many aspects of visual attention by just two mechanisms for selection of information: filtering and pigeonholing....... These mechanisms are described in a set of simple equations, which allow TVA to mathematically model a large number of classical results in the attention literature. The theory explains psychological and neuroscientific findings by the same equations; TVA is a complete theory of visual attention, linking mind...

  13. Crowded Field Galaxy Photometry: Precision Colors in the CLASH Clusters

    Science.gov (United States)

    Connor, Thomas; Donahue, Megan; Kelson, Daniel D.; Moustakas, John; Coe, Dan; Postman, Marc; Bradley, Larry D.; Koekemoer, Anton M.; Melchior, Peter; Umetsu, Keiichi; Voit, G. Mark

    2017-10-01

    We present a new method for photometering objects in galaxy clusters. We introduce a mode-filtering technique for removing spatially variable backgrounds, improving both detection and photometric accuracy (roughly halving the scatter in the red sequence compared to previous catalogs of the same clusters). This method is based on robustly determining the distribution of background pixel values and should provide comparable improvement in photometric analysis of any crowded fields. We produce new multiwavelength catalogs for the 25 CLASH cluster fields in all 16 bandpasses from the UV through the near-IR, as well as rest-frame magnitudes. A comparison with spectroscopic values from the literature finds a ˜ 30 % decrease in the redshift deviation from previously released CLASH photometry. This improvement in redshift precision, in combination with a detection scheme designed to maximize purity, yields a substantial upgrade in cluster member identification over the previous CLASH galaxy catalog. We construct luminosity functions for each cluster, reliably reaching depths of at least 4.5 mag below M* in every case, and deeper still in several clusters. We measure M* , α, and their redshift evolution, assuming the cluster populations are coeval, and find little to no evolution of α ,-0.9≲ ≲ -0.8, and M* values consistent with passive evolution. We present a catalog of galaxy photometry, photometric and spectroscopic redshifts, and rest-frame photometry for the full fields of view of all 25 CLASH clusters. Not only will our new photometric catalogs enable new studies of the properties of CLASH clusters, but mode-filtering techniques, such as those presented here, should greatly enhance the data quality of future photometric surveys of crowded fields.

  14. Cellular automaton model of crowd evacuation inspired by slime mould

    Science.gov (United States)

    Kalogeiton, V. S.; Papadopoulos, D. P.; Georgilas, I. P.; Sirakoulis, G. Ch.; Adamatzky, A. I.

    2015-04-01

    In all the living organisms, the self-preservation behaviour is almost universal. Even the most simple of living organisms, like slime mould, is typically under intense selective pressure to evolve a response to ensure their evolution and safety in the best possible way. On the other hand, evacuation of a place can be easily characterized as one of the most stressful situations for the individuals taking part on it. Taking inspiration from the slime mould behaviour, we are introducing a computational bio-inspired model crowd evacuation model. Cellular Automata (CA) were selected as a fully parallel advanced computation tool able to mimic the Physarum's behaviour. In particular, the proposed CA model takes into account while mimicking the Physarum foraging process, the food diffusion, the organism's growth, the creation of tubes for each organism, the selection of optimum tube for each human in correspondence to the crowd evacuation under study and finally, the movement of all humans at each time step towards near exit. To test the model's efficiency and robustness, several simulation scenarios were proposed both in virtual and real-life indoor environments (namely, the first floor of office building B of the Department of Electrical and Computer Engineering of Democritus University of Thrace). The proposed model is further evaluated in a purely quantitative way by comparing the simulation results with the corresponding ones from the bibliography taken by real data. The examined fundamental diagrams of velocity-density and flow-density are found in full agreement with many of the already published corresponding results proving the adequacy, the fitness and the resulting dynamics of the model. Finally, several real Physarum experiments were conducted in an archetype of the aforementioned real-life environment proving at last that the proposed model succeeded in reproducing sufficiently the Physarum's recorded behaviour derived from observation of the aforementioned

  15. Cloud-Enhanced Robotic System for Smart City Crowd Control

    Directory of Open Access Journals (Sweden)

    Akhlaqur Rahman

    2016-12-01

    Full Text Available Cloud robotics in smart cities is an emerging paradigm that enables autonomous robotic agents to communicate and collaborate with a cloud computing infrastructure. It complements the Internet of Things (IoT by creating an expanded network where robots offload data-intensive computation to the ubiquitous cloud to ensure quality of service (QoS. However, offloading for robots is significantly complex due to their unique characteristics of mobility, skill-learning, data collection, and decision-making capabilities. In this paper, a generic cloud robotics framework is proposed to realize smart city vision while taking into consideration its various complexities. Specifically, we present an integrated framework for a crowd control system where cloud-enhanced robots are deployed to perform necessary tasks. The task offloading is formulated as a constrained optimization problem capable of handling any task flow that can be characterized by a Direct Acyclic Graph (DAG. We consider two scenarios of minimizing energy and time, respectively, and develop a genetic algorithm (GA-based approach to identify the optimal task offloading decisions. The performance comparison with two benchmarks shows that our GA scheme achieves desired energy and time performance. We also show the adaptability of our algorithm by varying the values for bandwidth and movement. The results suggest their impact on offloading. Finally, we present a multi-task flow optimal path sequence problem that highlights how the robot can plan its task completion via movements that expend the minimum energy. This integrates path planning with offloading for robotics. To the best of our knowledge, this is the first attempt to evaluate cloud-based task offloading for a smart city crowd control system.

  16. Understanding crowd-powered search groups: a social network perspective.

    Science.gov (United States)

    Zhang, Qingpeng; Wang, Fei-Yue; Zeng, Daniel; Wang, Tao

    2012-01-01

    Crowd-powered search is a new form of search and problem solving scheme that involves collaboration among a potentially large number of voluntary Web users. Human flesh search (HFS), a particular form of crowd-powered search originated in China, has seen tremendous growth since its inception in 2001. HFS presents a valuable test-bed for scientists to validate existing and new theories in social computing, sociology, behavioral sciences, and so forth. In this research, we construct an aggregated HFS group, consisting of the participants and their relationships in a comprehensive set of identified HFS episodes. We study the topological properties and the evolution of the aggregated network and different sub-groups in the network. We also identify the key HFS participants according to a variety of measures. We found that, as compared with other online social networks, HFS participant network shares the power-law degree distribution and small-world property, but with a looser and more distributed organizational structure, leading to the diversity, decentralization, and independence of HFS participants. In addition, the HFS group has been becoming increasingly decentralized. The comparisons of different HFS sub-groups reveal that HFS participants collaborated more often when they conducted the searches in local platforms or the searches requiring a certain level of professional knowledge background. On the contrary, HFS participants did not collaborate much when they performed the search task in national platforms or the searches with general topics that did not require specific information and learning. We also observed that the key HFS information contributors, carriers, and transmitters came from different groups of HFS participants.

  17. Understanding crowd-powered search groups: a social network perspective.

    Directory of Open Access Journals (Sweden)

    Qingpeng Zhang

    Full Text Available BACKGROUND: Crowd-powered search is a new form of search and problem solving scheme that involves collaboration among a potentially large number of voluntary Web users. Human flesh search (HFS, a particular form of crowd-powered search originated in China, has seen tremendous growth since its inception in 2001. HFS presents a valuable test-bed for scientists to validate existing and new theories in social computing, sociology, behavioral sciences, and so forth. METHODOLOGY: In this research, we construct an aggregated HFS group, consisting of the participants and their relationships in a comprehensive set of identified HFS episodes. We study the topological properties and the evolution of the aggregated network and different sub-groups in the network. We also identify the key HFS participants according to a variety of measures. CONCLUSIONS: We found that, as compared with other online social networks, HFS participant network shares the power-law degree distribution and small-world property, but with a looser and more distributed organizational structure, leading to the diversity, decentralization, and independence of HFS participants. In addition, the HFS group has been becoming increasingly decentralized. The comparisons of different HFS sub-groups reveal that HFS participants collaborated more often when they conducted the searches in local platforms or the searches requiring a certain level of professional knowledge background. On the contrary, HFS participants did not collaborate much when they performed the search task in national platforms or the searches with general topics that did not require specific information and learning. We also observed that the key HFS information contributors, carriers, and transmitters came from different groups of HFS participants.

  18. Agent Based Modeling and Simulation of Pedestrian Crowds In Panic Situations

    KAUST Repository

    Alrashed, Mohammed

    2016-11-01

    The increasing occurrence of panic stampedes during mass events has motivated studying the impact of panic on crowd dynamics and the simulation of pedestrian flows in panic situations. The lack of understanding of panic stampedes still causes hundreds of fatalities each year, not to mention the scarce methodical studies of panic behavior capable of envisaging such crowd dynamics. Under those circumstances, there are thousands of fatalities and twice that many of injuries every year caused be crowd stampede worldwide, despite the tremendous efforts of crowd control and massive numbers of safekeeping forces. Pedestrian crowd dynamics are generally predictable in high-density crowds where pedestrians cannot move freely and thus gives rise to self-propelling interactions between pedestrians. Although every pedestrian has personal preferences, the motion dynamics can be modeled as a social force in such crowds. These forces are representations of internal preferences and objectives to perform certain actions or movements. The corresponding forces can be controlled for each individual to represent a different variety of behaviors that can be associated with panic situations such as escaping danger, clustering, and pushing. In this thesis, we use an agent-based model of pedestrian behavior in panic situations to predict the collective human behavior in such crowd dynamics. The proposed simulations suggests a practical way to alleviate fatalities and minimize the evacuation time in panic situations. Moreover, we introduce contagious panic and pushing behavior, resulting in a more realistic crowd dynamics model. The proposed methodology describes the intensity and spread of panic for each individual as a function of distances between pedestrians.

  19. Value-in-context in Crowd-funding ecosystems: how context frames value co-creation

    OpenAIRE

    Quero, María José; Kelleher, Carol; Ventura, Rafael

    2014-01-01

    The aim of the present paper is to analyse if the phenomenon of crowd funding can be considered a service ecosystem, where all of the actors generate resources and co-create value for and within the system. A qualitative, multiple case base approach is used to analyze six crowd-funding initiatives in the Spanish arts sector. The findings reveal seven types of value co-creation and six actors that interact on three levels: micro–meso–macro, illustrating that crowd-funding can be considered a ...

  20. Visual dependence and BPPV.

    Science.gov (United States)

    Agarwal, K; Bronstein, A M; Faldon, M E; Mandalà, M; Murray, K; Silove, Y

    2012-06-01

    The increased visual dependence noted in some vestibular patients may be secondary to their vertigo. We examine whether a single, brief vertigo attack, such as in benign paroxysmal positional vertigo (BPPV), modifies visual dependency. Visual dependency was measured before and after the Hallpike manoeuvre with (a) the Rod and Frame and the Rod and Disc techniques whilst seated and (b) the postural sway induced by visual roll-motion stimulation. Three subject groups were studied: 20 patients with BPPV (history and positive Hallpike manoeuvre; PosH group), 20 control patients (history of BPPV but negative Hallpike manoeuvre; NegH group) and 20 normal controls. Our findings show that while both patient groups showed enhanced visual dependency, the PosH and the normal control group decreased visual dependency on repetition of the visual tasks after the Hallpike manoeuvre. NegH patients differed from PosH patients in that their high visual dependency did not diminish on repetition of the visual stimuli; they scored higher on the situational characteristic questionnaire ('visual vertigo' symptoms) and showed higher incidence of migraine. We conclude that long term vestibular symptoms increase visual dependence but a single BPPV attack does not increase it further. Repetitive visual motion stimulation induces adaptation in visual dependence in peripheral vestibular disorders such as BPPV. A positional form of vestibular migraine may underlie the symptoms of some patients with a history of BPPV but negative Hallpike manoeuvre. The finding that they have non adaptable increased visual dependency may explain visuo-vestibular symptoms in this group and, perhaps more widely, in patients with migraine.

  1. Category selectivity in human visual cortex: Beyond visual object recognition

    NARCIS (Netherlands)

    Peelen, M.V.; Downing, P.E.

    2017-01-01

    Human ventral temporal cortex shows a categorical organization, with regions responding selectively to faces, bodies, tools, scenes, words, and other categories. Why is this? Traditional accounts explain category selectivity as arising within a hierarchical system dedicated to visual object

  2. The development of a quick-running prediction tool for the assessment of human injury owing to terrorist attack within crowded metropolitan environments

    Science.gov (United States)

    Pope, Daniel J.

    2011-01-01

    In the aftermath of the London ‘7/7’ attacks in 2005, UK government agencies required the development of a quick-running tool to predict the weapon and injury effects caused by the initiation of a person borne improvised explosive device (PBIED) within crowded metropolitan environments. This prediction tool, termed the HIP (human injury predictor) code, was intended to: — assist the security services to encourage favourable crowd distributions and densities within scenarios of ‘sensitivity’;— provide guidance to security engineers concerning the most effective location for protection systems;— inform rescue services as to where, in the case of such an event, individuals with particular injuries will be located;— assist in training medical personnel concerning the scope and types of injuries that would be sustained as a consequence of a particular attack;— assist response planners in determining the types of medical specialists (burns, traumatic amputations, lungs, etc.) required and thus identify the appropriate hospitals to receive the various casualty types.This document describes the algorithms used in the development of this tool, together with the pertinent underpinning physical processes. From its rudimentary beginnings as a simple spreadsheet, the HIP code now has a graphical user interface (GUI) that allows three-dimensional visualization of results and intuitive scenario set-up. The code is underpinned by algorithms that predict the pressure and momentum outputs produced by PBIEDs within open and confined environments, as well as the trajectories of shrapnel deliberately placed within the device to increase injurious effects. Further logic has been implemented to transpose these weapon effects into forms of human injury depending on where individuals are located relative to the PBIED. Each crowd member is subdivided into representative body parts, each of which is assigned an abbreviated injury score after a particular

  3. Macromolecular crowding induced elongation and compaction of single DNA molecules confined in a nanochannel.

    Science.gov (United States)

    Zhang, Ce; Shao, Pei Ge; van Kan, Jeroen A; van der Maarel, Johan R C

    2009-09-29

    The effect of dextran nanoparticles on the conformation and compaction of single DNA molecules confined in a nanochannel was investigated with fluorescence microscopy. It was observed that the DNA molecules elongate and eventually condense into a compact form with increasing volume fraction of the crowding agent. Under crowded conditions, the channel diameter is effectively reduced, which is interpreted in terms of depletion in DNA segment density in the interfacial region next to the channel wall. Confinement in a nanochannel also facilitates compaction with a neutral crowding agent at low ionic strength. The threshold volume fraction for condensation is proportional to the size of the nanoparticle, due to depletion induced attraction between DNA segments. We found that the effect of crowding is not only related to the colligative properties of the agent and that confinement is also important. It is the interplay between anisotropic confinement and osmotic pressure which gives the elongated conformation and the possibility for condensation at low ionic strength.

  4. Parallel Motion Simulation of Large-Scale Real-Time Crowd in a Hierarchical Environmental Model

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2012-01-01

    Full Text Available This paper presents a parallel real-time crowd simulation method based on a hierarchical environmental model. A dynamical model of the complex environment should be constructed to simulate the state transition and propagation of individual motions. By modeling of a virtual environment where virtual crowds reside, we employ different parallel methods on a topological layer, a path layer and a perceptual layer. We propose a parallel motion path matching method based on the path layer and a parallel crowd simulation method based on the perceptual layer. The large-scale real-time crowd simulation becomes possible with these methods. Numerical experiments are carried out to demonstrate the methods and results.

  5. Crowd modeling framework using fast head detection and shape-aware matching

    Science.gov (United States)

    Zhou, Tao; Yang, Jie; Loza, Artur; Bhaskar, Harish; Al-Mualla, Mohammed

    2015-03-01

    A framework for crowd modeling using a combination of multiple kernel learning (MKL)-based fast head detection and shape-aware matching is proposed. First, the MKL technique is used to train a classifier for head detection using a combination of the histogram of oriented gradient and local binary patterns feature sets. Further, the head detection process is accelerated by implementing the classification procedure only at those spatial locations in the image where the gradient points overlap with moving objects. Such moving objects are determined using an adaptive background subtraction technique. Finally, the crowd is modeled as a deformable shape through connected boundary points (head detection) and matched with the subsequent detection from the next frame in a shape-aware manner. Experimental results obtained from crowded videos show that the proposed framework, while being characterized by a low computation load, performs better than other state-of-art techniques and results in reliable crowd modeling.

  6. Molecular Crowding Enhances Native Structure and Stability of α/β Protein Flavodoxin

    National Research Council Canada - National Science Library

    Loren Stagg; Shao-Qing Zhang; Margaret S. Cheung; Pernilla Wittung-Stafshede

    2007-01-01

    To investigate the consequences of macromolecular crowding on the behavior of a globular protein, we performed a combined experimental and computational study on the 148-residue single-domain α/β...

  7. Molecular crowding enhances native structure and stability of  / protein flavodoxin

    National Research Council Canada - National Science Library

    Stagg, L; Zhang, S.-Q; Cheung, M. S; Wittung-Stafshede, P

    2007-01-01

    To investigate the consequences of macromolecular crowding on the behavior of a globular protein, we performed a combined experimental and computational study on the 148-residue single-domain [alpha]/[beta...

  8. Effects of Macromolecular Crowding on Alcohol Dehydrogenase Activity Are Substrate-Dependent.

    Science.gov (United States)

    Wilcox, A E; LoConte, Micaela A; Slade, Kristin M

    2016-06-28

    Enzymes operate in a densely packed cellular environment that rarely matches the dilute conditions under which they are studied. To better understand the ramifications of this crowding, the Michaelis-Menten kinetics of yeast alcohol dehydrogenase (YADH) were monitored spectrophotometrically in the presence of high concentrations of dextran. Crowding decreased the maximal rate of the reaction by 40% for assays with ethanol, the primary substrate of YADH. This observation was attributed to slowed release of the reduced β-nicotinamide adenine dinucleotide product, which is rate-limiting. In contrast, when larger alcohols were used as the YADH substrate, the rate-limiting step becomes hydride transfer and crowding instead increased the maximal rate of the reaction by 20-40%. This work reveals the importance of considering enzyme mechanism when evaluating the ways in which crowding can alter kinetics.

  9. Protein Crowding within the Postsynaptic Density Can Impede the Escape of Membrane Proteins

    NARCIS (Netherlands)

    Li, TP; Song, Y; Mac Gillavry, H.D.; Blanpied, TA; Raghavachari, S

    2016-01-01

    Mechanisms regulating lateral diffusion and positioning of glutamate receptors within the postsynaptic density (PSD) determine excitatory synaptic strength. Scaffold proteins in the PSD are abundant receptor binding partners, yet electron microscopy suggests that the PSD is highly crowded,

  10. Crowding versus molecular seeding: NMR studies of protein aggregation in hen egg white

    Science.gov (United States)

    Sanfelice, D.; Adrover, M.; Martorell, G.; Pastore, A.; Temussi, P. A.

    2012-06-01

    In living systems, proteins are surrounded by many other macromolecules of different nature, at high total concentrations. In the last few years, there has been an increasing effort to study biological macromolecules directly in natural crowded environments, such as in intact bacterial cells or by mimicking natural crowding by adding proteins, polysaccharides or even synthetic polymers. We have recently proposed hen egg white (HEW) as a suitable, natural medium to study macromolecules in crowding conditions. Here, we show that HEW can increase dramatically the aggregation kinetics of proteins with an in-built tendency to associate. By dissecting the mechanism we demonstrate that only part of this effect is due to crowding, while another factor playing an important role is the interaction with proteins from the milieu. High molecular weight glycoproteins present in HEW act as efficient molecular seeds for aggregation. Our results bear important consequences for in-cell NMR studies and suggest a role of glycosylated proteins in aggregation.

  11. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound Radiology and You Sponsored by Image/Video Gallery Your ... Explains CT Colonography (Virtual colonoscopy) Transcript Welcome to Radiology Info dot org! Hi, I’m Dr. Elliot ...

  12. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome to Radiology Info dot org Hello! I’m Dr. Ramji ...

  13. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual colonoscopy) Transcript Welcome to Radiology Info dot org! ... colonography or, as it is more commonly known, virtual colonoscopy. Virtual colonoscopy is a diagnostic imaging test ...

  14. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome to Radiology Info dot org Hello! ... d like to talk to you about nuclear medicine. Nuclear medicine offers the potential to identify disease ...

  15. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... and You Take our survey Sponsored by Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual colonoscopy) ... Carotid Intima-Media Thickness Test Medical Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound Radiology and You ...

  16. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... and You Take our survey Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome ... Carotid Intima-Media Thickness Test Medical Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound Radiology and You ...

  17. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... Video: Pelvic Ultrasound Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript ... by a special camera and computer to create images of the inside of your body. If you’ ...

  18. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... Video: Pelvic Ultrasound Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual ... to allow for inflation with air while CT images are being taken. If you’re scheduled for ...

  19. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... of Radiology (IDoR) Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript ... by a special camera and computer to create images of the inside of your body. If you’ ...

  20. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... Pelvic Ultrasound Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual colonoscopy) ... asked to wear a gown. After the CT scan you can return to your normal diet and ...

  1. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome to Radiology Info dot org ... I’d like to talk to you about nuclear medicine. Nuclear medicine offers the potential to identify ...

  2. Interrelationship of steric stabilization and self-crowding of a glycosylated protein

    DEFF Research Database (Denmark)

    Høiberg-Nielsen, Rasmus; Westh, Peter; Skov, L.K.

    2009-01-01

    In the eukaryotic cell, protein glycosylation takes place in the crowded environment of the endoplasmatic reticulum. With the purpose of elucidating the impact of high concentration on the interactions of glycoproteins, we have conducted a series of small-angle x-ray scattering experiments on the...... from the glycans contribute to steric stabilization of the protein, and that glycosylation helps to sustain repulsive electrostatic interactions under crowded conditions. In combination, this aids in stabilizing high concentrations of glycosylated proteins....

  3. Public Spending and Private Investment: Test of Crowding-out Effects through Re-sampling

    OpenAIRE

    Ghassan, Hassan B.

    2002-01-01

    The purpose of this research is to test and evaluate the crowding-out effect of the investment expenditure in public sector on the investment effort by private sector by using data from Moroccan Economy. After the theoretical background of crowding-out effects in many domains of investment, we introduce the interests variables which express the budget policy of a government and monetary policy of the central bank, and shows the global effective demand addressed to economy. This requires the i...

  4. Multiscale diffusion of a molecular probe in a crowded environment: a concept

    Science.gov (United States)

    Currie, Megan; Thao, Chang; Timerman, Randi; Welty, Robb; Berry, Brenden; Sheets, Erin D.; Heikal, Ahmed A.

    2015-08-01

    Living cells are crowded with macromolecules and organelles. Yet, it is not fully understood how macromolecular crowding affects the myriad of biochemical reactions, transport and the structural stability of biomolecules that are essential to cellular function and survival. These molecular processes, with or without electrostatic interactions, in living cells are therefore expected to be distinct from those carried out in test tube in dilute solutions where excluded volumes are absent. Thus there is an urgent need to understand the macromolecular crowding effects on cellular and molecular biophysics towards quantitative cell biology. In this report, we investigated how biomimetic crowding affects both the rotational and translation diffusion of a small probe (rhodamine green, RhG). For biomimetic crowding agents, we used Ficoll-70 (synthetic polymer), bovine serum albumin and ovalbumin (proteins) at various concentrations in a buffer at room temperature. As a control, we carried out similar measurements on glycerolenriched buffer as an environment with homogeneous viscosity as a function of glycerol concentration. The corresponding bulk viscosity was measured independently to test the validity of the Stokes-Einstein model of a diffusing species undergoing a random walk. For rotational diffusion (ps-ns time scale), we used time-resolved anisotropy measurements to examine potential binding of RhG as a function of the crowding agents (surface structure and size). For translational diffusion (μs-s time scale), we used fluorescence correlation spectroscopy for single-molecule fluctuation analysis. Our results allow us to examine the diffusion model of a molecular probe in crowded environments as a function of concentration, length scale, homogeneous versus heterogeneous viscosity, size and surface structures. These biomimetic crowding studies, using non-invasive fluorescence spectroscopy methods, represent an important step towards understanding cellular biophysics and

  5. Skierarchy: Extending the Power of Crowdsourcing Using a Hierarchy of Domain Experts, Crowd and Machine Learning

    Science.gov (United States)

    2012-11-01

    art to art- lovers . 5 www.lexmachina.com creates a structured knowledge base from unstructured legal dockets. 6 www.esparklearning.com recommends...For IRAT, we used the same crowd that we used for TRAT, but significantly enhanced the workflow and UI to adapt to the requirements of IRAT. In...quality. In addition to micro tasking and qualification, skill enhancement of crowd through training, expert coaching/feedback and appropriate

  6. Crowd-Sourced Assessment of Technical Skill: A Valid Method for Discriminating Basic Robotic Surgery Skills.

    Science.gov (United States)

    White, Lee W; Kowalewski, Timothy M; Dockter, Rodney Lee; Comstock, Bryan; Hannaford, Blake; Lendvay, Thomas S

    2015-11-01

    A surgeon's skill in the operating room has been shown to correlate with a patient's clinical outcome. The prompt accurate assessment of surgical skill remains a challenge, in part, because expert faculty reviewers are often unavailable. By harnessing the power of large readily available crowds through the Internet, rapid, accurate, and low-cost assessments may be achieved. We hypothesized that assessments provided by crowd workers highly correlate with expert surgeons' assessments. A group of 49 surgeons from two hospitals performed two dry-laboratory robotic surgical skill assessment tasks. The performance of these tasks was video recorded and posted online for evaluation using Amazon Mechanical Turk. The surgical tasks in each video were graded by (n=30) varying crowd workers and (n=3) experts using a modified global evaluative assessment of Robotic Skills (GEARS) grading tool, and the mean scores were compared using Cronbach's alpha statistic. GEARS evaluations from the crowd were obtained for each video and task and compared with the GEARS ratings from the expert surgeons. The crowd-based performance scores agreed with the performance assessments by experts with a Cronbach's alpha of 0.84 and 0.92 for the two tasks, respectively. The assessment of surgical skill by crowd workers resulted in a high degree of agreement with the scores provided by expert surgeons in the evaluation of basic robotic surgical dry-laboratory tasks. Crowd responses cost less and were much faster to acquire. This study provides evidence that crowds may provide an adjunctive method for rapidly providing feedback of skills to training and practicing surgeons.

  7. Effect of larval crowding on mating competitiveness of Anopheles gambiae mosquitoes

    Directory of Open Access Journals (Sweden)

    Knols Bart GJ

    2005-09-01

    Full Text Available Abstract Background The success of sterile or transgenic Anopheles for malaria control depends on their mating competitiveness within wild populations. Current evidence suggests that transgenic mosquitoes have reduced fitness. One means of compensating for this fitness deficit would be to identify environmental conditions that increase their mating competitiveness, and incorporate them into laboratory rearing regimes. Methods Anopheles gambiae larvae were allocated to three crowding treatments with the same food input per larva. Emerged males were competed against one another for access to females, and their corresponding longevity and energetic reserves measured. Results Males from the low-crowding treatment were much more likely to acquire the first mating. They won the first female approximately 11 times more often than those from the high-crowding treatment (Odds ratio = 11.17 and four times more often than those from the medium-crowding treatment (Odds ratio = 3.51. However, there was no overall difference in the total number of matings acquired by males from different treatments (p = 0.08. The survival of males from the low crowding treatment was lower than those from other treatments. The body size and teneral reserves of adult males did not differ between crowding treatments, but larger males were more likely to acquire mates than small individuals. Conclusion Larval crowding and body size have strong, independent effects on the mating competitiveness of adult male An. gambiae. Thus manipulation of larval crowding during mass rearing could provide a simple technique for boosting the competitiveness of sterile or transgenic male mosquitoes prior to release.

  8. Investigating the In-Vehicle Crowding Cost Functions for Public Transit Modes

    OpenAIRE

    Qin, Feifei

    2014-01-01

    In the densely populated metropolitan area, empirical studies have found that overcrowding inside transit vehicles has become substantially worse and worse over recent years. Chronic in-vehicle crowding is not only caused by a lack of physical infrastructure, but also triggered by inadequate service provisions. Given the prevalence of overcrowded transit vehicles, this paper conducts both quantitative and qualitative studies, especially focusing on remodeling the in-vehicle crowding cost func...

  9. Negative feedback in ants: crowding results in less trail pheromone deposition.

    Science.gov (United States)

    Czaczkes, Tomer J; Grüter, Christoph; Ratnieks, Francis L W

    2013-04-06

    Crowding in human transport networks reduces efficiency. Efficiency can be increased by appropriate control mechanisms, which are often imposed externally. Ant colonies also have distribution networks to feeding sites outside the nest and can experience crowding. However, ants do not have external controllers or leaders. Here, we report a self-organized negative feedback mechanism, based on local information, which downregulates the production of recruitment signals in crowded parts of a network by Lasius niger ants. We controlled crowding by manipulating trail width and the number of ants on a trail, and observed a 5.6-fold reduction in the number of ants depositing trail pheromone from least to most crowded conditions. We also simulated crowding by placing glass beads covered in nest-mate cuticular hydrocarbons on the trail. After 10 bead encounters over 20 cm, forager ants were 45 per cent less likely to deposit pheromone. The mechanism of negative feedback reported here is unusual in that it acts by downregulating the production of a positive feedback signal, rather than by direct inhibition or the production of an inhibitory signal.

  10. Modelling of Joint Crowd-Structure System Using Equivalent Reduced-DOF System

    Directory of Open Access Journals (Sweden)

    Jackie Sim

    2007-01-01

    Full Text Available For human assembly structures in which the mass of the crowd is significant compared to that of the structure, it is necessary to model the passive crowd as a dynamic system added to the main structural system. Earlier work by the authors has analysed the frequency response of a joint crowd-structure system in which the structure is treated as a single degree-of-freedom (SDOF system and the seated and standing crowds are each modelled as a two degree-of-freedom (2DOF system. It was found that the occupied structure has dynamic properties different to the empty structure. This paper investigates representing the joint crowd-structure system as an equivalent reduced-DOF system that would have the advantage of simplifying the analysis. The modal properties of the equivalent reduced-DOF system, if known, can give a useful indication of how the passive crowd affects the modal properties of the occupied structure. Two equivalent reduced-DOF systems are investigated – SDOF and 3DOF systems. The errors between the responses of the equivalent systems and the full model are calculated and presented in the paper. The results show that the full model exhibits the behaviour of a SDOF system for structures with natural frequencies less than 4 Hz (when empty, whereas for structures with natural frequencies above 4 Hz the equivalent 3DOF system gives a better fit to the full model.

  11. Household crowding associated with childhood otitis media hospitalisations in New Zealand.

    Science.gov (United States)

    Bowie, Christopher; Pearson, Amber L; Campbell, Malcolm; Barnett, Ross

    2014-06-01

    To examine the association between hospitalisations for otitis media and area-level measures of household crowding among children in New Zealand. Counts of hospital admissions for otitis media by census area unit were offset against population data from the 2006 national census. Area-level household crowding, exposure to tobacco smoke in the home, equivalised income and individual-level characteristics age and sex were adjusted for. To examine effect modification by ethnicity, three separate poisson models were examined for the total, Māori and non-Māori populations. Household crowding was significantly associated with hospital admissions for otitis media after adjustment in all three models. Neighbourhoods with the highest compared to the lowest proportion of crowded homes exhibited incidence rate ratios of 1.25 (95%CI 1.12-1.37) in the total population, 1.59 (95%CI 1.21-2.04) in the Māori restricted model and 1.17 (95%CI 1.06-1.32) in the non-Māori restricted model. Otitis media hospitalisations are associated with area-level measures of household crowding and other risk factors in this ecological study. The largest increase in otitis media incidence relative to neighbourhood rates of household crowding was exhibited among Māori cases of otitis media. This study adds weight to the growing body of literature linking infectious disease risk to overcrowding in the home. © 2014 The Authors. ANZJPH © 2014 Public Health Association of Australia.

  12. Periventricular leukomalacia: an important cause of visual and ocular motility dysfunction in children.

    Science.gov (United States)

    Jacobson, L K; Dutton, G N

    2000-01-01

    The immature visual system in infants born preterm is vulnerable to adverse events during the perinatal period. Periventricular leukomalacia affecting the optic radiation has now become the principal cause of visual impairment and dysfunction in children born prematurely. Visual dysfunction is characterized by delayed visual maturation, subnormal visual acuity, crowding, visual field defects, and visual perceptual-cognitive problems. Magnetic resonance imaging is the method of choice for diagnosing this brain lesion, which is associated with optic disk abnormalities, strabismus, nystagmus, and deficient visually guided eye movements. Children with periventricular leukomalacia may present to the ophthalmologist within a clinical spectrum from severe cerebral visual impairment in combination with cerebral palsy and mental retardation to only early-onset esotropia, normal intellectual level, and no cerebral palsy. Optimal educational and habilitational strategies need to be developed to meet the needs of this group of visually impaired children.

  13. Visual and perceptual characteristics, ocular motility and strabismus in children with periventricular leukomalacia.

    Science.gov (United States)

    Jacobson, L; Ygge, J; Flodmark, O; Ek, U

    2002-06-01

    The immature visual system is vulnerable to adverse events. Periventricular leukomalacia (PVL), an end-stage lesion after hypoxia-ischemia at gestational age 24-34 weeks affecting the visual radiation, has become a principal cause of visual impairment in children. Cerebral visual dysfunction caused by PVL is characterized by delayed visual maturation, subnormal visual acuity, crowding, visual field defects, and visual perceptual-cognitive problems. Magnetic resonance imaging is the method of choice for diagnosing this brain lesion, which is associated with optic disk abnormalities, strabismus, nystagmus, and deficient visually guided eye movements. Children with PVL may present to the ophthalmologist within a clinical spectrum from severe visual impairment in combination with cerebral palsy to only early-onset esotropia, normal intellectual level and no cerebral palsy. Optimal educational and habilitational strategies need to be developed to meet the needs for this group of children.

  14. The efficient use of movies in a crowded curriculum.

    Science.gov (United States)

    Gallagher, Peter; Wilson, Nick; Jaine, Richard

    2014-04-01

    The undergraduate medical curriculum has earned a reputation for being overcrowded. The dilemma for educationalists is to determine what, if anything, can be jettisoned from a congested curriculum to accommodate new ideas or material. We report on a small study that demonstrated that when movies are used innovatively, they enhance students' understanding of medicine and also have a minimal impact on the 'crowded' curriculum. During a 5-week-long Public Health module students could borrow from the medical school library, free of charge, one or more movies, each with a public health message. In the final week of the module a 1.5-hour-long class was allocated when each student offered a brief synopsis of a movie that they had watched, and then identified key public health issues discussed in the movie. Our study supports the view that the creative use of classroom time not only allows for better use of the timetable, but also proves to be an integrative, stimulating, and fun way for medical students to learn. © 2014 John Wiley & Sons Ltd.

  15. Learning From the Crowd in Terminology Mapping: The LOINC Experience.

    Science.gov (United States)

    Dixon, Brian E; Hook, John; Vreeman, Daniel J

    2015-01-01

    National policies in the United States require the use of standard terminology for data exchange between clinical information systems. However, most electronic health record systems continue to use local and idiosyncratic ways of representing clinical observations. To improve mappings between local terms and standard vocabularies, we sought to make existing mappings (wisdom) from healt care organizations (the Crowd) available to individuals engaged in mapping processes. We developed new functionality to display counts of local terms and organizations that had previously mapped to a given Logical Observation Identifiers Names and Codes (LOINC) code. Further, we enabled users to view the details of those mappings, including local term names and the organizations that create the mappings. Users also would have the capacity to contribute their local mappings to a shared mapping repository. In this article, we describe the new functionality and its availability to implementers who desire resources to make mapping more efficient and effective. Copyright© by the American Society for Clinical Pathology (ASCP).

  16. Detecting animals in African Savanna with UAVs and the crowds

    Science.gov (United States)

    Rey, Nicolas; Volpi, Michele; Joost, Stéphane; Tuia, Devis

    2017-10-01

    Unmanned aerial vehicles (UAVs) offer new opportunities for wildlife monitoring, with several advantages over traditional field-based methods. They have readily been used to count birds, marine mammals and large herbivores in different environments, tasks which are routinely performed through manual counting in large collections of images. In this paper, we propose a semi-automatic system able to detect large mammals in semi-arid Savanna. It relies on an animal-detection system based on machine learning, trained with crowd-sourced annotations provided by volunteers who manually interpreted sub-decimeter resolution color images. The system achieves a high recall rate and a human operator can then eliminate false detections with limited effort. Our system provides good perspectives for the development of data-driven management practices in wildlife conservation. It shows that the detection of large mammals in semi-arid Savanna can be approached by processing data provided by standard RGB cameras mounted on affordable fixed wings UAVs.

  17. Investigating molecular crowding within nuclear pores using polarization-PALM

    Science.gov (United States)

    Fu, Guo; Tu, Li-Chun; Zilman, Anton

    2017-01-01

    The key component of the nuclear pore complex (NPC) controlling permeability, selectivity, and the speed of nucleocytoplasmic transport is an assembly of natively unfolded polypeptides, which contain phenylalanine-glycine (FG) binding sites for nuclear transport receptors. The architecture and dynamics of the FG-network have been refractory to characterization due to the paucity of experimental methods able to probe the mobility and density of the FG-polypeptides and embedded macromolecules within intact NPCs. Combining fluorescence polarization, super-resolution microscopy, and mathematical analyses, we examined the rotational mobility of fluorescent probes at various locations within the FG-network under different conditions. We demonstrate that polarization PALM (p-PALM) provides a rich source of information about low rotational mobilities that are inaccessible with bulk fluorescence anisotropy approaches, and anticipate that p-PALM is well-suited to explore numerous crowded cellular environments. In total, our findings indicate that the NPC’s internal organization consists of multiple dynamic environments with different local properties. PMID:28949296

  18. Measuring and Modelling Crowd Flows - Fusing Stationary and Tracking Data

    CERN Document Server

    Treiber, Martin

    2016-01-01

    The two main data categories of vehicular traffic flow, stationary detector data and floating-car data, are also available for many Marathons and other mass-sports events: Loop detectors and other stationary data sources find their counterpart in the RFID tags of the athletes recording the split times at several stations during the race. Additionally, more and more athletes use smart-phone apps generating track data points that are the equivalent of floating-car data. We present a methodology to detect congestions and estimate the location of jam-fronts, the delay times, and the spatio-temporal speed and density distribution of the athlete's crowd flow by fusing these two data sources based on a first-order macroscopic model with triangular fundamental diagram. The method can be used in real-time or for analyzing past events. Using synthetic "ground truth" data generated by simulations with the Intelligent-Driver Model, we show that, in a real-time application, the proposed algorithm is robust and effective w...

  19. Library on Crowd Behavior for Agents Treatment on Videogames

    Directory of Open Access Journals (Sweden)

    M. Proenza

    2013-01-01

    Full Text Available Abstract This paper covers the investigation process and further design and implementation of a library on crowd behaviors for videogames. Three methods were studied in order to pick up one of them, resulting to be Steering Behaviors method the one selected to be adopted. The library supports simulations with a large number of moving agents. It also copes with polygonal obstacles avoidance. Additionally, simulations can be adapted to many contexts by tuning some parameters. The library consists of an original design mostly based on Command Pattern that allows it to be easily usable and extendable.   Resumen Este documento cubre el proceso de investigación y el diseño e implementación de una biblioteca en los comportamientos de multitud de videojuegos. Tres métodos fueron estudiados con el fin de recoger a uno de ellos, el resultado es el método de dirección Comportamientos que se ha seleccionado para su adopción. La biblioteca admite simulaciones con un gran número de agentes móviles. También hace frente a la evitación obstáculos poligonales. Además, las simulaciones se pueden adaptar a diferentes contextos mediante la regulación de algunos parámetros. La biblioteca consta de un diseño original basado principalmente en modelo de comandos que permite que sea fácilmente utilizable y extensible.

  20. States leverage telepsychiatry solutions to ease ED crowding, accelerate care.

    Science.gov (United States)

    2015-02-01

    Many states are having success turning to telepsychiatry-based solutions to connect mental health patients with needed care while also decompressing crowded EDs. Just one year into a statewide telepsychiatry initiative in North Carolina (NC-STeP), administrators say the approach has saved as much as $7 million, and hospital demand for the service is higher than anticipated. In Texas, mental health emergency centers (MHEC) that use telepsychiatry to connect patients in rural areas with needed psychiatric care are freeing up EDs to focus on medical care. In just 11 months, 91 North Carolina hospitals have at least started the process to engage in NC-STeP. Much of the savings from NC-STeP come from involuntary commitment orders being overturned as a result of the telepsychiatry consults, reducing the need for expensive inpatient care. Implementing NC-STeP has involved multiple hurdles including credentialing difficulties and technical/firewall challenges. The Texas model provides 24/7 availability of psychiatrists via telemedicine through a network of MHECs. In-person staff at the MHECs perform basic screening tests and blood draws so that medical clearance can be achieved without the need for an ED visit in most cases. Funding for the MHECs comes from the state, hospitals in the region, and local governmental authorities that reap savings or benefits from the initiative.

  1. Visual Literacy and Message Design

    Science.gov (United States)

    Pettersson, Rune

    2009-01-01

    Many researchers from different disciplines have explained their views and interpretations and written about visual literacy from their various perspectives. Visual literacy may be applied in almost all areas such as advertising, anatomy, art, biology, business presentations, communication, education, engineering, etc. (Pettersson, 2002a). Despite…

  2. Monte Carlo simulations of enzymatic reactions in crowded media. Effect of the enzyme-obstacle relative size.

    Science.gov (United States)

    Pitulice, Laura; Vilaseca, Eudald; Pastor, Isabel; Madurga, Sergio; Garcés, Josep Lluís; Isvoran, Adriana; Mas, Francesc

    2014-05-01

    We perform Monte Carlo simulations in three-dimensional (3D) lattice in order to study diffusion-controlled and mixed activation-diffusion reactions following an irreversible Michaelis-Menten scheme in crowded media. The simulation data reveal the rate coefficient dependence on time for diffusion-controlled bimolecular reactions developing in three-dimensional media with obstacles, as predicted by fractal kinetics approach. For the cases of mixed activation-diffusion reactions, the fractality of the reaction decreases as the activation control increases. We propose a modified form of the Zipf-Mandelbrot equation to describe the time dependence of the rate coefficient, k(t)=k0(1+t/τ)(-)(h). This equation provides a good description of the fractal regime and it may be split into two terms: one that corresponds to the initial rate constant (k0) and the other one correlated with the kinetics fractality. Additionally, the proposed equation contains and links two limit expressions corresponding to short and large periods of time: k1=k0 (for t≪τ) that relates to classical kinetics and the well-known Kopelman's equation k∼t(-)(h) (for t≫τ) associated to fractal kinetics. The τ parameter has the meaning of a crossover time between these two limiting behaviours. The value of k0 is mainly dependent on the excluded volume and the enzyme-obstacle relative size. This dependence can be explained in terms of the radius of an average confined volume that every enzyme molecule feels, and correlates very well with the crossover length obtained in previous studies of enzyme diffusion in crowding media. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Social dynamics in emergency evacuations: Disentangling crowd's attraction and repulsion effects

    Science.gov (United States)

    Haghani, Milad; Sarvi, Majid

    2017-06-01

    The social dynamics of crowds in emergency escape scenarios have been conventionally modelled as the net effect of virtual forces exerted by the crowd on each individual (as self-driven particles), with the magnitude of the influence formulated as decreasing functions of inter-individual distances and the direction of effect assumed to be transitioning from repulsion to attraction by distance. Here, we revisit this conventional assumption using laboratory experimental data. We show based on robust econometric hypothesis-testing methods that individuals' perception of other escapees differs based on whether those individuals are jamming around exit destinations or are on the move towards the destinations. Also, for moving crowds, it differs based on whether the escape destination chosen by the moving flow is visible or invisible to the individual. The presence of crowd jams around a destination, also the movement of crowd flows towards visible destinations are both perceived on average as repulsion (or disutility) effects (with the former showing significantly larger magnitude than the latter). The movement of crowd flows towards an invisible destination, however, is on average perceived as attraction (or utility) effect. Yet, further hypothesis testing showed that neither of those effects in isolation determines adequately whether an individual would merge with or diverge from the crowd. Rather, the social interaction factors act (at significant levels) in conjunction with the physical factors of the environments (including spatial distances to exit destinations and destinations' visibility). In brief, our finding disentangles the conditions under which individuals are more likely to show mass behaviour from the situations where they are more likely to break from the herd. It identifies two factors that moderate the perception of social interactions, ;crowds' jam/movement status; and ;environmental setup;. Our results particularly challenge the taxonomy of

  4. Consensus-based Recommendations for Research Priorities Related to Interventions to Safeguard Patient Safety in the Crowded Emergency Department

    OpenAIRE

    Fee, Christopher; Hall, Kendall; Morrison, J. Bradley; Stephens, Robert; Cosby, Karen; Fairbanks, Rollin J; Youngberg, Barbara; Lenehan, Gail; Abualenain, Jameel; O’Connor, Kevin; Wears, Robert

    2011-01-01

    This article describes the results of the Interventions to Safeguard Safety breakout session of the 2011 Academic Emergency Medicine (AEM) consensus conference entitled “Interventions to Assure Quality in the Crowded Emergency Department.” Using a multistep nominal group technique, experts in emergency department (ED) crowding, patient safety, and systems engineering defined knowledge gaps and priority research questions related to the maintenance of safety in the crowded ED. Consensus was re...

  5. Explaining Errors in Children's Questions

    Science.gov (United States)

    Rowland, Caroline F.

    2007-01-01

    The ability to explain the occurrence of errors in children's speech is an essential component of successful theories of language acquisition. The present study tested some generativist and constructivist predictions about error on the questions produced by ten English-learning children between 2 and 5 years of age. The analyses demonstrated that,…

  6. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions ... Radiologist Explains Nuclear Medicine Transcript Welcome to Radiology Info dot org Hello! I’m Dr. Ramji Rajendran, ...

  7. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... of Radiology (IDoR) Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual ... to allow for inflation with air while CT images are being taken. If you’re scheduled for ...

  8. Your Radiologist Explains Nuclear Medicine

    Medline Plus

    Full Text Available ... Radiology (IDoR) Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Nuclear Medicine Transcript Welcome ... Carotid Intima-Media Thickness Test Medical Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound November 8 is ...

  9. Your Radiologist Explains CT Colonography

    Medline Plus

    Full Text Available ... Radiology (IDoR) Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains CT Colonography (Virtual colonoscopy) ... Carotid Intima-Media Thickness Test Medical Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound November 8 is ...

  10. A simple quantitative model of macromolecular crowding effects on protein folding: Application to the murine prion protein(121-231)

    Science.gov (United States)

    Bergasa-Caceres, Fernando; Rabitz, Herschel A.

    2013-06-01

    A model of protein folding kinetics is applied to study the effects of macromolecular crowding on protein folding rate and stability. Macromolecular crowding is found to promote a decrease of the entropic cost of folding of proteins that produces an increase of both the stability and the folding rate. The acceleration of the folding rate due to macromolecular crowding is shown to be a topology-dependent effect. The model is applied to the folding dynamics of the murine prion protein (121-231). The differential effect of macromolecular crowding as a function of protein topology suffices to make non-native configurations relatively more accessible.

  11. PREFACE: Complex dynamics of fluids in disordered and crowded environments Complex dynamics of fluids in disordered and crowded environments

    Science.gov (United States)

    Coslovich, Daniele; Kahl, Gerhard; Krakoviack, Vincent

    2011-06-01

    Over the past two decades, the dynamics of fluids under nanoscale confinement has attracted much attention. Motivation for this rapidly increasing interest is based on both practical and fundamental reasons. On the practical and rather applied side, problems in a wide range of scientific topics, such as polymer and colloidal sciences, rheology, geology, or biophysics, benefit from a profound understanding of the dynamical behaviour of confined fluids. Further, effects similar to those observed in confinement are expected in fluids whose constituents have strong size or mass asymmetry, and in biological systems where crowding and obstruction phenomena in the cytosol are responsible for clear separations of time scales for macromolecular transport in the cell. In fundamental research, on the other hand, the interest focuses on the complex interplay between confinement and structural relaxation, which is responsible for the emergence of new phenomena in the dynamics of the system: in confinement, geometric constraints associated with the pore shape are imposed to the adsorbed fluids and an additional characteristic length scale, i.e. the pore size, comes into play. For many years, the topic has been mostly experimentally driven. Indeed, a broad spectrum of systems has been investigated by sophisticated experimental techniques, while theoretical and simulation studies were rather scarce due to conceptual and computational issues. In the past few years, however, theory and simulations could largely catch up with experiments. On one side, new theories have been put forward that duly take into account the porosity, the connectivity, and the randomness of the confinement. On the other side, the ever increasing available computational power now allows investigations that were far out of reach a few years ago. Nowadays, instead of isolated state points, systematic investigations on the dynamics of confined fluids, covering a wide range of system parameters, can be realized

  12. Visual art and visual perception

    NARCIS (Netherlands)

    Koenderink, Jan J.

    2015-01-01

    Visual art and visual perception ‘Visual art’ has become a minor cul-de-sac orthogonal to THE ART of the museum directors and billionaire collectors. THE ART is conceptual, instead of visual. Among its cherished items are the tins of artist’s shit (Piero Manzoni, 1961, Merda d’Artista) “worth their

  13. Improvement of healthcare quality in pediatric neurology by crowd technologies

    Directory of Open Access Journals (Sweden)

    O. V. Guzeva

    2016-01-01

    , the solution of which requires that the government should invest a great deal of assets and may be rational only when crowd technologies are applied.

  14. Online collective action dynamics of the crowd in social media

    CERN Document Server

    Agarwal, Nitin; Wigand, Rolf T

    2014-01-01

    This book explores and explains collective action in the new generation of Information and Communication Technologies (ICT) enabled by Web 2.0, also referred to as social media, and its capacity to help critical decision and policy making.

  15. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  16. Abnormal event detection in crowded scenes using two sparse dictionaries with saliency

    Science.gov (United States)

    Yu, Yaping; Shen, Wei; Huang, He; Zhang, Zhijiang

    2017-05-01

    Abnormal event detection in crowded scenes is a challenging problem due to the high density of the crowds and the occlusions between individuals. We propose a method using two sparse dictionaries with saliency to detect abnormal events in crowded scenes. By combining a multiscale histogram of optical flow (MHOF) and a multiscale histogram of oriented gradient (MHOG) into a multiscale histogram of optical flow and gradient, we are able to represent the feature of a spatial-temporal cuboid without separating the individuals in the crowd. While MHOF captures the temporal information, MHOG encodes both spatial and temporal information. The combination of these two features is able to represent the cuboid's appearance and motion characteristics even when the density of the crowds becomes high. An abnormal dictionary is added to the traditional sparse model with only a normal dictionary included. In addition, the saliency of the testing sample is combined with two sparse reconstruction costs on the normal and abnormal dictionary to measure the normalness of the testing sample. The experiment results show the effectiveness of our method.

  17. Optimal Acceleration-Velocity-Bounded Trajectory Planning in Dynamic Crowd Simulation

    Directory of Open Access Journals (Sweden)

    Fu Yue-wen

    2014-01-01

    Full Text Available Creating complex and realistic crowd behaviors, such as pedestrian navigation behavior with dynamic obstacles, is a difficult and time consuming task. In this paper, we study one special type of crowd which is composed of urgent individuals, normal individuals, and normal groups. We use three steps to construct the crowd simulation in dynamic environment. The first one is that the urgent individuals move forward along a given path around dynamic obstacles and other crowd members. An optimal acceleration-velocity-bounded trajectory planning method is utilized to model their behaviors, which ensures that the durations of the generated trajectories are minimal and the urgent individuals are collision-free with dynamic obstacles (e.g., dynamic vehicles. In the second step, a pushing model is adopted to simulate the interactions between urgent members and normal ones, which ensures that the computational cost of the optimal trajectory planning is acceptable. The third step is obligated to imitate the interactions among normal members using collision avoidance behavior and flocking behavior. Various simulation results demonstrate that these three steps give realistic crowd phenomenon just like the real world.

  18. A Crowd Avoidance Method Using Circular Avoidance Path for Robust Person Following

    Directory of Open Access Journals (Sweden)

    Kohei Morishita

    2017-01-01

    Full Text Available A life-support service robot must avoid both static and dynamic obstacles for working in a real environment. Here, a static obstacle means an obstacle that does not move, and a dynamic obstacle is the one that moves. Assuming the robot is following a target person, we discuss how the robot avoids a crowd through which the target person passes and arrives at the target position. The purpose of this paper is to propose a crowd avoidance method that makes a robot to be able to avoid both static and dynamic obstacles. The method uses the surface points of the obstacles to form an avoidance region, and the robot moves along the edge of the region. We conducted experiments assuming various situations such that the robot was blocked, there was a wide gap in the crowd, or a person in the crowd yielded for the robot to pass through. As an experimental result, it was confirmed the robot could avoid the crowd even when the obstacles were aligned in an “inverted wedge” shape.

  19. Crowding and delivery of healthcare in emergency departments: the European perspective.

    LENUS (Irish Health Repository)

    Jayaprakash, Namita

    2009-11-01

    Emergency department (ED) crowding is a multifactorial problem, resulting in increased ED waiting times, decreased patient satisfaction and deleterious domino effects on the entire hospital. Although difficult to define and once limited to anecdotal evidence, crowding is receiving more attention as attempts are made to quantify the problem objectively. It is a worldwide phenomenon with regional influences, as exemplified when analyzing the problem in Europe compared to that of the United States. In both regions, an aging population, limited hospital resources, staff shortages and delayed ancillary services are key contributors; however, because the structure of healthcare differs from country to country, varying influences affect the issue of crowding. The approach to healthcare delivery as a right of all people, as opposed to a free market commodity, depends on governmental organization and appropriation of funds. Thus, public funding directly influences potential crowding factors, such as number of hospital beds, community care facilities, and staffing. Ultimately ED crowding is a universal problem with distinctly regional root causes; thus, any approach to address the problem must be tailored to regional influences.

  20. A natural and readily available crowding agent: NMR studies of proteins in hen egg white.

    Science.gov (United States)

    Martorell, Gabriel; Adrover, Miquel; Kelly, Geoff; Temussi, Piero Andrea; Pastore, Annalisa

    2011-05-01

    In vitro studies of biological macromolecules are usually performed in dilute, buffered solutions containing one or just a few different biological macromolecules. Under these conditions, the interactions among molecules are diffusion limited. On the contrary, in living systems, macromolecules of a given type are surrounded by many others, at very high total concentrations. In the last few years, there has been an increasing effort to study biological macromolecules directly in natural crowded environments, as in intact bacterial cells or by mimicking natural crowding by adding proteins, polysaccharides, or even synthetic polymers. Here, we propose the use of hen egg white (HEW) as a simple natural medium, with all features of the media of crowded cells, that could be used by any researcher without difficulty and inexpensively. We present a study of the stability and dynamics behavior of model proteins in HEW, chosen as a prototypical, readily accessible natural medium that can mimic cytosol. We show that two typical globular proteins, dissolved in HEW, give NMR spectra very similar to those obtained in dilute buffers, although dynamic parameters are clearly affected by the crowded medium. The thermal stability of one of these proteins, measured in a range comprising both heat and cold denaturation, is also similar to that in buffer. Our data open new possibilities to the study of proteins in natural crowded media. Copyright © 2010 Wiley-Liss, Inc.

  1. Explaining mirror-touch synesthesia.

    Science.gov (United States)

    Ward, Jamie; Banissy, Michael J

    2015-01-01

    Mirror-touch synesthesia (MTS) is the conscious experience of tactile sensations induced by seeing someone else touched. This paper considers two different, although not mutually exclusive, theoretical explanations and, in the final section, considers the relation between MTS and other forms of synesthesia and also other kinds of vicarious perception (e.g., contagious yawning). The Threshold Theory explains MTS in terms of hyper-activity within a mirror system for touch and/or pain. This offers a good account for some of the evidence (e.g., from fMRI) but fails to explain the whole pattern (e.g., structural brain differences outside of this system; performance on some tests of social cognition). The Self-Other Theory explains MTS in terms of disturbances in the ability to distinguish the self from others. This can be construed in terms of over-extension of the bodily self in to others, or as difficulties in the control of body-based self-other representations. In this account, MTS is a symptom of a broader cognitive profile. We suggest this meets the criteria for synesthesia, despite the proximal causal mechanisms remaining largely unknown, and that the tendency to localize vicarious sensory experiences distinguishes it from other kinds of seemingly related phenomena (e.g., non-localized affective responses to observing pain).

  2. Explaining the gender wealth gap.

    Science.gov (United States)

    Ruel, Erin; Hauser, Robert M

    2013-08-01

    To assess and explain the United States' gender wealth gap, we use the Wisconsin Longitudinal Study to examine wealth accumulated by a single cohort over 50 years by gender, by marital status, and limited to the respondents who are their family's best financial reporters. We find large gender wealth gaps between currently married men and women, and between never-married men and women. The never-married accumulate less wealth than the currently married, and there is a marital disruption cost to wealth accumulation. The status-attainment model shows the most power in explaining gender wealth gaps between these groups explaining about one-third to one-half of the gap, followed by the human-capital explanation. In other words, a lifetime of lower earnings for women translates into greatly reduced wealth accumulation. After controlling for the full model, we find that a gender wealth gap remains between married men and women that we speculate may be related to gender differences in investment strategies and selection effects.

  3. Interactive data visualization foundations, techniques, and applications

    CERN Document Server

    Ward, Matthew; Keim, Daniel

    2015-01-01

    Interactive Data Visualization: Foundations, Techniques, and Applications, Second Edition provides all the theory, details, and tools necessary to build visualizations and systems involving the visualization of data. In color throughout, it explains basic terminology and concepts, algorithmic and software engineering issues, and commonly used techniques and high-level algorithms. Full source code is provided for completing implementations.

  4. Visual Electricity Demonstrator

    Science.gov (United States)

    Lincoln, James

    2017-09-01

    The Visual Electricity Demonstrator (VED) is a linear diode array that serves as a dynamic alternative to an ammeter. A string of 48 red light-emitting diodes (LEDs) blink one after another to create the illusion of a moving current. Having the current represented visually builds an intuitive and qualitative understanding about what is happening in a circuit. In this article, I describe several activities for this device and explain how using this technology in the classroom can enhance the understanding and appreciation of physics.

  5. Ameliorating the emergency department workflow by involving the observation unit: effects on crowding

    Directory of Open Access Journals (Sweden)

    Primiano Iannone

    2015-06-01

    Full Text Available Crowding adversely affects the performance of emergency departments (EDs by worsening efficiency, timeliness of care, clinical outcomes and patients’ satisfaction. We describe in this study our attempt at improving crowding by modifying the roles and workflow of the ED physicians. The observation unit physician was given the additional duty of prioritizing admissions and managing unclear, complex cases, which were previously under the responsibility of front line emergency physicians. We analyzed two corresponding periods, both before the intervention (9897 ED attendances in 2012 and after the intervention (10,297 attendances in 2013. Most of the crowding indices improved significantly, including timeliness of triage, of first medical contact, access to resus area, and overall length of stay in ED. Also, emergency hospital admissions, average specialist consultations and imaging studies per patient decreased significantly. The observation unit workload increased. There was no significant excess of adverse events.

  6. Dynamics-Based Stranded-Crowd Model for Evacuation in Building Bottlenecks

    Directory of Open Access Journals (Sweden)

    Lidi Huang

    2013-01-01

    Full Text Available In high-density public buildings, it is difficult to evacuate. So in this paper, we propose a novel quantitative evacuation model to insure people’s safety and reduce the risk of crowding. We analyze the mechanism of arch-like clogging phenomena during evacuation and the influencing factors in emergency situations at bottleneck passages; then we design a model based on crowd dynamics and apply the model to a stadium example. The example is used to compare evacuation results of crowd density with different egress widths in stranded zones. The results show this model proposed can guide the safe and dangerous egress widths in performance design and can help evacuation routes to be selected and optimized.

  7. Modeling the capability of penetrating a jammed crowd to eliminate freezing transition

    Science.gov (United States)

    Mohammed Mahmod, Shuaib

    2016-05-01

    Frozen state from jammed state is one of the most interesting aspects produced when simulating the multidirectional pedestrian flow of high density crowds. Cases of real life situations for such a phenomenon are not exhaustively treated. Our observations in the Hajj crowd show that freezing transition does not occur very often. On the contrary, penetrating a jammed crowd is a common aspect. We believe the kindness of pedestrians facing others whose walking is blocked is a main factor in eliminating the frozen state as well as in relieving the jammed state. We refine the social force model by incorporating a new social force to enable the simulated pedestrians to mimic the real behavior observed in the Hajj area. Simulations are performed to validate the work qualitatively.

  8. Household behaviour crowds out support for climate change policy when sufficient progress is perceived

    Science.gov (United States)

    Werfel, Seth H.

    2017-07-01

    Household actions and government policies are both necessary to mitigate the effects of climate change. However, household behaviour may crowd out public support for government action by creating the perception of sufficient progress. Here we demonstrate this crowding-out effect in public opinion using survey experiments with more than 14,000 participants in Japan. Subjects who were randomly assigned to report their energy-saving actions following the shutdown of the Fukushima power plant were less likely to support a tax increase on carbon emissions. Treatment effects were larger for subjects who had completed more actions. Further evidence suggests that the crowding-out effect may have been driven by an increase in the perceived importance of individual actions relative to government regulation and a decrease in the perceived issue importance of energy and environmental sustainability.

  9. Average interradicular sites for miniscrew insertion: should dental crowding be considered?

    DEFF Research Database (Denmark)

    Tepedino, Michele; Cattaneo, Paolo; Masedu, Francesco

    2017-01-01

    OBJECTIVE: To define a map of interradicular spaces where miniscrew can be likely placed at a level covered by attached gingiva, and to assess if a correlation between crowding and availability of space exists. METHODS: Panoramic radiographs and digital models of 40 patients were selected according...... to the inclusion criteria. Interradicular spaces were measured on panoramic radiographs, while tooth size-arch length discrepancy was assessed on digital models. Statistical analysis was performed to evaluate if interradicular spaces are influenced by the presence of crowding. RESULTS: In the mandible, the most...... canines and lateral incisors, and between mandibular first and second premolars revealed to be influenced by the presence of dental crowding. CONCLUSIONS: The average interradicular sites map hereby proposed can be used as a general guide for miniscrew insertion at the very beginning of orthodontic...

  10. Effect on Perceived Stimulation dan Perceived Crowding on the Decision of the Unplanned Purchase (Impulse Buying

    Directory of Open Access Journals (Sweden)

    Enggal Sriwardiningsih

    2011-11-01

    Full Text Available Purchase decisions aren’t made necessarily planned, because impulsive buying is such a result of environmental stimuli shopping. Things affecting unplanned purchasing decisions are perceived by stimulation and crowding. The purpose of this study is to determine whether there are influences between perceived crowding and stimulation of impulse buying simultaneously or partial. The object used is one of the largest retailers in Cilegon. This research design is quantitative analysis of the consumer unit. The collecting data technique includes using questionnaires, interviews, and literature from previous research. Data processed using the SPSS 16.0 program through the validity and reliability, normality test, and regression analysis. The study states that there is significant influence between perceived crowding and perceived stimulation both simultaneous and partial response to impulse buying. 

  11. A Distance Measure Comparison to Improve Crowding in Multi-Modal Problems.

    Energy Technology Data Exchange (ETDEWEB)

    D. Todd VOllmer; Terence Soule; Milos Manic

    2010-08-01

    Solving multi-modal optimization problems are of interest to researchers solving real world problems in areas such as control systems and power engineering tasks. Extensions of simple Genetic Algorithms, particularly types of crowding, have been developed to help solve these types of problems. This paper examines the performance of two distance measures, Mahalanobis and Euclidean, exercised in the processing of two different crowding type implementations against five minimization functions. Within the context of the experiments, empirical evidence shows that the statistical based Mahalanobis distance measure when used in Deterministic Crowding produces equivalent results to a Euclidean measure. In the case of Restricted Tournament selection, use of Mahalanobis found on average 40% more of the global optimum, maintained a 35% higher peak count and produced an average final best fitness value that is 3 times better.

  12. Visual Scripting.

    Science.gov (United States)

    Halas, John

    Visual scripting is the coordination of words with pictures in sequence. This book presents the methods and viewpoints on visual scripting of fourteen film makers, from nine countries, who are involved in animated cinema; it contains concise examples of how a storybook and preproduction script can be prepared in visual terms; and it includes a…

  13. Explaining the Evolution of Poverty

    DEFF Research Database (Denmark)

    Arndt, Channing; Hussain, Azhar; Jones, Edward Samuel

    2012-01-01

    We provide a comprehensive approach for analyzing the evolution of poverty using Mozambique as a case study. Bringing together data from disparate sources, we develop a novel “back-casting” framework that links a dynamic computable general equilibrium model to a micro-simulation poverty module....... This framework provides a new approach to explaining and decomposing the evolution of poverty, as well as to examining rigorously the coherence between poverty, economic growth, and inequality outcomes. Finally, various simple but useful and rarely-applied approaches to considering regional changes in poverty...

  14. Explaining (Missing) Regulator Paradigm Shifts

    DEFF Research Database (Denmark)

    Wigger, Angela; Buch-Hansen, Hubert

    2014-01-01

    of competition regulation is heaving into sight. It sets out to explain this from the vantage point of a critical political economy perspective, which identifies the circumstances under which a crisis can result in a regulatory paradigm shift. Contrasting the current situation with the shift in EC/EU competition...... capitalism; the social power configuration underpinning the neoliberal order remains unaltered; no clear counter-project has surfaced; the European Commission has been (and remains) in a position to oppose radical changes; and finally, there are no signs of a wider paradigm shift in the EU's regulatory...

  15. Explaining the Gender Wealth Gap

    OpenAIRE

    Ruel, Erin; Hauser, Robert M.

    2013-01-01

    To assess and explain the United States’ gender wealth gap, we use the Wisconsin Longitudinal Study to examine wealth accumulated by a single cohort over 50 years by gender, by marital status, and limited to the respondents who are their family’s best financial reporters. We find large gender wealth gaps between currently married men and women, and never-married men and women. The never-married accumulate less wealth than the currently married, and there is a marital disruption cost to wealth...

  16. The CrowdMag App - turning your smartphone into a travelling magnetic observatory

    Science.gov (United States)

    Saltus, Richard; Nair, Manoj

    2017-04-01

    In 2014, we started the "CrowdMag" Project to collect vector magnetic data from digital magnetometers in smartphones. In October 2014, we released our first-generation Android and iOS apps. Currently, the CrowdMag Project has more than 15,000 enthusiastic users contributing more than 12 million magnetic data points from around the world. NOAA's National Centers for Environmental Information (NCEI), in partnership with the University of Colorado's Cooperative Institute for Research in the Environmental Sciences (CIRES) develops magnetic field models to aid navigation, resource exploration and scientific research. We use observatories, satellites and ship/airborne surveys to measure the magnetic data. However, the measurements leave gaps in coverage, particularly for short-wavelength urban noise. Our ultimate goal is to use data from the CrowdMag Project to improve global magnetic data coverage. Here we present some early results from the analysis of the crowdsourced magnetic data. A global magnetic model derived solely based on CrowdMag data is generally consistent with satellite-derived models such as World Magnetic Model. A unique contribution of the CrowdMag Project is the collection of ground level magnetic data in densely populated regions with an unprecedented spatial resolution. For example, we show a magnetic map (by binning the data collected into 100x100m cells) of central Boulder using 170,000 data points collected by about 60 devices over the duration October 2014- January 2016. The median magnetic field value is consistent with the expected magnitude of the Earth's background magnetic field. The standard deviation of the CrowdMag total field (F) values is much higher than the expected natural (i.e., diurnal and geologic) magnetic field variation. However, the phone's magnetometer is sensitive enough to capture the larger magnitude magnetic signature from the urban magnetic sources. We discuss the reliability of crowdsourced magnetic maps and their

  17. Three-dimensional stochastic off-lattice model of binding chemistry in crowded environments.

    Directory of Open Access Journals (Sweden)

    Byoungkoo Lee

    Full Text Available Molecular crowding is one of the characteristic features of the intracellular environment, defined by a dense mixture of varying kinds of proteins and other molecules. Interaction with these molecules significantly alters the rates and equilibria of chemical reactions in the crowded environment. Numerous fundamental activities of a living cell are strongly influenced by the crowding effect, such as protein folding, protein assembly and disassembly, enzyme activity, and signal transduction. Quantitatively predicting how crowding will affect any particular process is, however, a very challenging problem because many physical and chemical parameters act synergistically in ways that defy easy analysis. To build a more realistic model for this problem, we extend a prior stochastic off-lattice model from two-dimensional (2D to three-dimensional (3D space and examine how the 3D results compare to those found in 2D. We show that both models exhibit qualitatively similar crowding effects and similar parameter dependence, particularly with respect to a set of parameters previously shown to act linearly on total reaction equilibrium. There are quantitative differences between 2D and 3D models, although with a generally gradual nonlinear interpolation as a system is extended from 2D to 3D. However, the additional freedom of movement allowed to particles as thickness of the simulation box increases can produce significant quantitative change as a system moves from 2D to 3D. Simulation results over broader parameter ranges further show that the impact of molecular crowding is highly dependent on the specific reaction system examined.

  18. Folding dynamics of Trp-cage in the presence of chemical interference and macromolecular crowding. I.

    Science.gov (United States)

    Samiotakis, Antonios; Cheung, Margaret S

    2011-11-07

    Proteins fold and function in the crowded environment of the cell's interior. In the recent years it has been well established that the so-called "macromolecular crowding" effect enhances the folding stability of proteins by destabilizing their unfolded states for selected proteins. On the other hand, chemical and thermal denaturation is often used in experiments as a tool to destabilize a protein by populating the unfolded states when probing its folding landscape and thermodynamic properties. However, little is known about the complicated effects of these synergistic perturbations acting on the kinetic properties of proteins, particularly when large structural fluctuations, such as protein folding, have been involved. In this study, we have first investigated the folding mechanism of Trp-cage dependent on urea concentration by coarse-grained molecular simulations where the impact of urea is implemented into an energy function of the side chain and/or backbone interactions derived from the all-atomistic molecular dynamics simulations with urea through a Boltzmann inversion method. In urea solution, the folding rates of a model miniprotein Trp-cage decrease and the folded state slightly swells due to a lack of contact formation between side chains at the terminal regions. In addition, the equilibrium m-values of Trp-cage from the computer simulations are in agreement with experimental measurements. We have further investigated the combined effects of urea denaturation and macromolecular crowding on Trp-cage's folding mechanism where crowding agents are modeled as hard-spheres. The enhancement of folding rates of Trp-cage is most pronounced by macromolecular crowding effect when the extended conformations of Trp-cast dominate at high urea concentration. Our study makes quantitatively testable predictions on protein folding dynamics in a complex environment involving both chemical denaturation and macromolecular crowding effects.

  19. The future of protected areas in a crowded world.

    Science.gov (United States)

    Harmon, D; Brechin, S R

    1994-01-01

    Population-environment interactions date back to Malthus and even Confucius who viewed humans as a threat to the planet. In contrast, pronatalists regard the human mind the ultimate resource and think that there is no limit to the number of people the earth can support. There are a few countries whose population is projected to be lower in 2025 than it was in 1990: Belgium, Bulgaria, Denmark, Greece, Hungary, and Italy. The highest population growth rates (3% and above) are in Africa, the Gulf states, and some other Islamic countries. Rates of 1-3% are common everywhere outside Europe. Almost all of the wealthiest countries are growing at the rate of less than 1%, while the poorest countries, except for China and Sri Lanka, are growing at rates of 2% or more. The world's continuing population growth rides on the fact that in developing countries 40% of the population is under the age of 15. Relentless urbanization will eradicate 1.4 billion acres of arable land from 1980 to 2000. In 1950, 13 of the 25 most populous cities were in less developed countries; by 2000, 20 out of 25 will be. Migration, especially rural-urban migration, has an impact. "Economic refugees" from impoverished rural areas, "environmental refugees" from overworked lands or disaster-stricken areas, and political refugees from wars or persecution crowd around protected areas. Some examples of the population-protected area interactions include Kenya (the 3.56% growth rate threatens the world-renowned national parks), Tanzania (its 3.28% rate of growth causes encroachment into protected areas), Congo (natural rainforests are disturbed), Gabon (the rate of growth is 4.01%), and Zaire (an annual increment of over 1 million people). The threat to unexploited wildlife in the Ivory Coast, direct pressure on forested protected areas in Malaysia, deforestation in the Philippines, in-migration into the Pelen in Guatemala, the situation of the Shenandoah National Park in the United States, and pressures

  20. A fuzzy-theory-based method for studying the effect of information transmission on nonlinear crowd dispersion dynamics

    Science.gov (United States)

    Fu, Libi; Song, Weiguo; Lo, Siuming

    2017-01-01

    Emergencies involved in mass events are related to a variety of factors and processes. An important factor is the transmission of information on danger that has an influence on nonlinear crowd dynamics during the process of crowd dispersion. Due to much uncertainty in this process, there is an urgent need to propose a method to investigate the influence. In this paper, a novel fuzzy-theory-based method is presented to study crowd dynamics under the influence of information transmission. Fuzzy functions and rules are designed for the ambiguous description of human states. Reasonable inference is employed to decide the output values of decision making such as pedestrian movement speed and directions. Through simulation under four-way pedestrian situations, good crowd dispersion phenomena are achieved. Simulation results under different conditions demonstrate that information transmission cannot always induce successful crowd dispersion in all situations. This depends on whether decision strategies in response to information on danger are unified and effective, especially in dense crowds. Results also suggest that an increase in drift strength at low density and the percentage of pedestrians, who choose one of the furthest unoccupied Von Neumann neighbors from the dangerous source as the drift direction at high density, is helpful in crowd dispersion. Compared with previous work, our comprehensive study improves an in-depth understanding of nonlinear crowd dynamics under the effect of information on danger.

  1. Protein crowding in lipid bilayers gives rise to non-Gaussian anomalous lateral diffusion of phospholipids and proteins

    DEFF Research Database (Denmark)

    Jeon, Jae Hyung; Javanainen, Matti; Martinez-Seara, Hector

    2016-01-01

    Biomembranes are exceptionally crowded with proteins with typical protein-to-lipid ratios being around 1:50-1:100. Protein crowding has a decisive role in lateral membrane dynamics as shown by recent experimental and computational studies that have reported anomalous lateral diffusion of phosphol...

  2. About implementing a Monte Carlo simulation algorithm for enzymatic reactions in crowded media

    Directory of Open Access Journals (Sweden)

    ADRIANA ISVORAN

    2006-01-01

    Full Text Available In this paper, several aspects of implementing a Monte Carlo simulation algorithm for studying the Michaelis–Menten mechanism of enzymatic reactions in crowded media are presented. Using a two dimensional lattice with obstacles, it is shown how the initial distribution of the reactants and obstacles on the lattice affects the values of the rate coefficients and the concentration of the reactants. The influence of the number of considered nearest neighbours and of the obstacle concentration on the values of the rate coefficients is also demonstrated. The results strongly suggest fractal kinetics for enzyme reactions in crowded media.

  3. Working Performance Analysis of Rolling Bearings Used in Mining Electric Excavator Crowd Reducer

    Science.gov (United States)

    Zhang, Y. H.; Hou, G.; Chen, G.; Liang, J. F.; Zheng, Y. M.

    2017-12-01

    Refer to the statistical load data of digging process, on the basis of simulation analysis of crowd reducer system dynamics, the working performance simulation analysis of rolling bearings used in crowd reducer of large mining electric excavator is completed. The contents of simulation analysis include analysis of internal load distribution, rolling elements contact stresses and rolling bearing fatigue life. The internal load characteristics of rolling elements in cylindrical roller bearings are obtained. The results of this study identified that all rolling bearings satisfy the requirements of contact strength and fatigue life. The rationality of bearings selection and arrangement is also verified.

  4. Treating dental crowding with mandibular incisor extraction in an Angle Class I patient

    Directory of Open Access Journals (Sweden)

    Gislana Braga Machado

    2015-06-01

    Full Text Available Mandibular dental crowding often encourages patients to seek orthodontic treatment. The orthodontist should decide between protrusion of incisors or decrease in dental volume so as to achieve proper alignment and leveling. The present study reports the treatment of an Angle Class I malocclusion adolescent female brachyfacial patient with severe mandibular dental crowding, increased curve of Spee and deep overbite. The patient was treated with extraction of a mandibular incisor. This case was presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO as a requirement for the title of certified by the BBO.

  5. Dialogue Police, Decision Making, and the Management of Public Order During Protest Crowd Events

    DEFF Research Database (Denmark)

    Gorringe, Hugo; Stott, Clifford; Rosie, Michael

    2012-01-01

    to facilitate peaceful protest through dialogue and communication. This paper reports upon a critical ‘test case’ for this ‘new approach’ by analysing the policing of a series of protests against Government policy across 3 days that surrounded a Government party conference in Sheffield, a large city...... making and enhanced police proportionality. The subsequent impact upon crowd dynamics allowed for an improved capacity for proactive public order management, encouraged ‘self-regulation’ in the crowd, and avoided the unnecessary police use of force at moments of tension. The implications of the analysis...... for theory and practice are discussed....

  6. Keeping the Peace: Social identity, procedural justice and the policing of football crowds

    OpenAIRE

    Stott, Clifford; Hoggett, James; Pearson, Geoff

    2012-01-01

    This paper explores the relevance of the Elaborated Social Identity Model of Crowd Behaviour and Procedural Justice Theory to an understanding of both the presence and absence of collective conflict during football (soccer) crowd events. It provides an analysis of data gathered during longitudinal ethnographic study of fans of Cardiff City Football Club—a group of supporters with a notorious history of involvement in ‘hooliganism’ within the English domestic Football Leagues. The analys...

  7. Value co-creation as determinat of succcess in crowd-funding experiencesin the cultural sector

    OpenAIRE

    Quero, María José; Ventura, Rafael; Santoja, Antonio

    2014-01-01

    The aim of the present study is to analyse the role of value co-creation on success crowd-funding experiences in the cultural sector. The relationships developed between actors can be considered as a type of collaborative behaviour model, which makes use of the potential offered by new technologies in actors who get order to benefit everyone. The analysis of the structure of the relationships between actors who get involved in crowd-funding is approached with the primary objective of finding ...

  8. Esthetic and functional rehabilitation of crowded mandibular anterior teeth using ceramic veneers: a case report.

    Science.gov (United States)

    de Andrade, Oswaldo Scopin; Ferreira, Luiz Alves; Hirata, Ronaldo; Rodrigues, Flavia Pires; D'Alpino, Paulo Henrique Perlatti; Di Hipolito, Vinicius

    2012-09-01

    The use of ceramic veneers to restore crowded teeth in the maxilla has been widely discussed in the literature. However, the use of this technique in the mandible has received little attention. Therefore, this case report describes the treatment of crowded mandibular anterior teeth using ceramic veneers. The primary treatment challenge in this region is the reduced tooth structure available for rehabilitation. Proper communication between the clinician and dental technician is required to achieve clinical success. This article presents a straightforward treatment plan and restorative technique that includes both the clinical and laboratory sequences necessary for predictable and stable postoperative outcomes.

  9. An Application of Graphics Processing Units to Geosimulation of Collective Crowd Behaviour

    Directory of Open Access Journals (Sweden)

    Cjoskāns Jānis

    2017-12-01

    Full Text Available The goal of the paper is to assess the ways for computational performance and efficiency improvement of collective crowd behaviour simulation by using parallel computing methods implemented on graphics processing unit (GPU. To perform an experimental evaluation of benefits of parallel computing, a new GPU-based simulator prototype is proposed and the runtime performance is analysed. Based on practical examples of pedestrian dynamics geosimulation, the obtained performance measurements are compared to several other available multiagent simulation tools to determine the efficiency of the proposed simulator, as well as to provide generic guidelines for the efficiency improvements of the parallel simulation of collective crowd behaviour.

  10. Treating dental crowding with mandibular incisor extraction in an Angle Class I patient.

    Science.gov (United States)

    Machado, Gislana Braga

    2015-01-01

    Mandibular dental crowding often encourages patients to seek orthodontic treatment. The orthodontist should decide between protrusion of incisors or decrease in dental volume so as to achieve proper alignment and leveling. The present study reports the treatment of an Angle Class I malocclusion adolescent female brachyfacial patient with severe mandibular dental crowding, increased curve of Spee and deep overbite. The patient was treated with extraction of a mandibular incisor. This case was presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO) as a requirement for the title of certified by the BBO.

  11. Data visualization

    CERN Document Server

    Azzam, Tarek

    2013-01-01

    Do you communicate data and information to stakeholders? In Part 1, we introduce recent developments in the quantitative and qualitative data visualization field and provide a historical perspective on data visualization, its potential role in evaluation practice, and future directions. Part 2 delivers concrete suggestions for optimally using data visualization in evaluation, as well as suggestions for best practices in data visualization design. It focuses on specific quantitative and qualitative data visualization approaches that include data dashboards, graphic recording, and geographic information systems (GIS). Readers will get a step-by-step process for designing an effective data dashboard system for programs and organizations, and various suggestions to improve their utility.

  12. Fractal-like kinetics of intracellular enzymatic reactions: a chemical framework of endotoxin tolerance and a possible non-specific contribution of macromolecular crowding to cross-tolerance.

    Science.gov (United States)

    Vasilescu, Catalin; Olteanu, Mircea; Flondor, Paul; Calin, George A

    2013-09-14

    The response to endotoxin (LPS), and subsequent signal transduction lead to the production of cytokines such as tumor necrosis factor-α (TNF-α) by innate immune cells. Cells or organisms pretreated with endotoxin enter into a transient state of hyporesponsiveness, referred to as endotoxin tolerance (ET) which represents a particular case of negative preconditioning. Despite recent progress in understanding the molecular basis of ET, there is no consensus yet on the primary mechanism responsible for ET and for the more complex cases of cross tolerance. In this study, we examined the consequences of the macromolecular crowding (MMC) and of fractal-like kinetics (FLK) of intracellular enzymatic reactions on the LPS signaling machinery. We hypothesized that this particular type of enzyme kinetics may explain the development of ET phenomenon. Our aim in the present study was to characterize the chemical kinetics framework in ET and determine whether fractal-like kinetics explains, at least in part, ET. We developed an ordinary differential equations (ODE) mathematical model that took into account the links between the MMC and the LPS signaling machinery leading to ET. We proposed that the intracellular fractal environment (MMC) contributes to ET and developed two mathematical models of enzyme kinetics: one based on Kopelman's fractal-like kinetics framework and the other based on Savageau's power law model. Kopelman's model provides a good image of the potential influence of a fractal intracellular environment (MMC) on ET. The Savageau power law model also partially explains ET. The computer simulations supported the hypothesis that MMC and FLK may play a role in ET. The model highlights the links between the organization of the intracellular environment, MMC and the LPS signaling machinery leading to ET. Our FLK-based model does not minimize the role of the numerous negative regulatory factors. It simply draws attention to the fact that macromolecular crowding can

  13. Hyperbolic scaling and computing in social crowds: Comment on "Human behaviours in evacuation crowd dynamics: From modelling to "big data" toward crisis management" by Nicola Bellomo et al.

    Science.gov (United States)

    Outada, Nisrine

    2016-09-01

    I have read with great interest the paper [5] where the authors present an overview and critical analysis of the literature on the modeling of the crowd dynamics with special attention to evacuation dynamics. The approach developed is based on suitable development of methods of the kinetic theory. Interactions, which lead to the decision choice, are modeled by theoretical tools of stochastic evolutionary game theory [11,12]. However, the paper [5] provides not only a survey focused on topics of great interest for our society, but also it looks ahead to a variety of interesting and challenging mathematical problems. Specifically, I am interested in the derivation of macroscopic (hydrodynamic) models from the underlying description given from the kinetic theory approach, more specifically by the kinetic theory for active particles [8]. A general reference on crowd modeling is the recently published book [10].

  14. Does Prison Crowding Predict Higher Rates of Substance Use Related Parole Violations? A Recurrent Events Multi-Level Survival Analysis.

    Science.gov (United States)

    Ruderman, Michael A; Wilson, Deirdra F; Reid, Savanna

    2015-01-01

    This administrative data-linkage cohort study examines the association between prison crowding and the rate of post-release parole violations in a random sample of prisoners released with parole conditions in California, for an observation period of two years (January 2003 through December 2004). Crowding overextends prison resources needed to adequately protect inmates and provide drug rehabilitation services. Violence and lack of access to treatment are known risk factors for drug use and substance use disorders. These and other psychosocial effects of crowding may lead to higher rates of recidivism in California parolees. Rates of parole violation for parolees exposed to high and medium levels of prison crowding were compared to parolees with low prison crowding exposure. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using a Cox model for recurrent events. Our dataset included 13070 parolees in California, combining individual level parolee data with aggregate level crowding data for multilevel analysis. Comparing parolees exposed to high crowding with those exposed to low crowding, the effect sizes from greatest to least were absconding violations (HR 3.56 95% CI: 3.05-4.17), drug violations (HR 2.44 95% CI: 2.00-2.98), non-violent violations (HR 2.14 95% CI: 1.73-2.64), violent and serious violations (HR 1.88 95% CI: 1.45-2.43), and technical violations (HR 1.86 95% CI: 1.37-2.53). Prison crowding predicted higher rates of parole violations after release from prison. The effect was magnitude-dependent and particularly strong for drug charges. Further research into whether adverse prison experiences, such as crowding, are associated with recidivism and drug use in particular may be warranted.

  15. What explains consciousness? Or…What consciousness explains?

    Science.gov (United States)

    Dulany, Donelson E

    2014-01-01

    In this invited commentary I focus on the topic addressed in three papers: De Sousa's (2013[1617]) Toward an Integrative Theory of Consciousness, a monograph with Parts 1 & 2, as well as commentaries by Pereira (2013a[59]) and Hirstein (2013[42]). All three are impressively scholarly and can stand-and shout-on their own. But theory of consciousness? My aim is to slice that topic into the two fundamentally different kinds of theories of consciousness, say what appears to be an ideology, out of behaviourism into cognitivism, now also influencing the quest for an "explanation of consciousness" in cognitive neuroscience. I will then say what can be expected given what we know of the complexity of brain structure, the richness of a conscious "vocabulary", and current technological limits of brain imaging. This will then turn to the strategy for examining "what consciousness explains"-metatheory, theories, mappings, and a methodology of competitive support, a methodology especially important where there are competing commitments. There are also increasingly common identifications of methodological bias in, along with failures to replicate, studies reporting unconscious controls in decision, social priming-as there have been in perception, learning, problem solving, etc. The literature critique has provided evidence taken as reducing, and in some cases eliminating, a role for conscious controls-a position consistent with that ideology out of behaviourism into cognitivism. It is an ideological position that fails to recognize the fundamental distinction between theoretical and metaphysical assertions.

  16. YouTube as a crowd-generated water level archive.

    Science.gov (United States)

    Michelsen, N; Dirks, H; Schulz, S; Kempe, S; Al-Saud, M; Schüth, C

    2016-10-15

    In view of the substantial costs associated with classic monitoring networks, participatory data collection methods can be deemed a promising option to obtain complementary data. An emerging trend in this field is social media mining, i.e., harvesting of pre-existing, crowd-generated data from social media. Although this approach is participatory in a broader sense, the users are mostly not aware of their participation in research. Inspired by this novel development, we demonstrate in this study that it is possible to derive a water level time series from the analysis of multiple YouTube videos. As an example, we studied the recent water level rise in Dahl Hith, a Saudi Arabian cave. To do so, we screened 16 YouTube videos of the cave for suitable reference points (e.g., cave graffiti). Then, we visually estimated the distances between these points and the water level and traced their changes over time. To bridge YouTube hiatuses, we considered own photos taken during two site visits. For the time period 2013-2014, we estimate a rise of 9.5m. The fact that this rise occurred at a somewhat constant rate of roughly 0.4m per month points towards a new and permanent water source, possibly two nearby lakes formed from treated sewage effluent. An anomaly in the rising rate is noted for autumn 2013 (1.3m per month). As this increased pace coincides with a cluster of rain events, we deem rapid groundwater recharge along preferential flow paths a likely cause. Despite the sacrifice in precision, we believe that YouTube harvesting may represent a viable option to gather historical water levels in data-scarce settings and that it could be adapted to other environments (e.g., flood extents). In certain areas, it might provide an additional tool for the monitoring toolbox, thereby possibly delivering hydrological data for water resources management. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Visual attention in posterior stroke

    DEFF Research Database (Denmark)

    Fabricius, Charlotte; Petersen, Anders; Iversen, Helle K

    Objective: Impaired visual attention is common following strokes in the territory of the middle cerebral artery, particularly in the right hemisphere. However, attentional effects of more posterior lesions are less clear. The aim of this study was to characterize visual processing speed...... and apprehension span following posterior cerebral artery (PCA) stroke. We also relate these attentional parameters to visual word recognition, as previous studies have suggested that reduced visual speed and span may explain pure alexia. Methods: Nine patients with MR-verified focal lesions in the PCA......-territory (four left PCA; four right PCA; one bilateral, all >1 year post stroke) were compared to 25 controls using single case statistics. Visual attention was characterized by a whole report paradigm allowing for hemifield-specific speed and span measurements. We also characterized visual field defects...

  18. Visual handicap in children.

    Science.gov (United States)

    Bull, M; Evans, P J; Maclean, H

    1982-05-01

    Vision is the primary mode of learning and if it is absent or impaired, other pathways must be stimulated. The range of appropriate services available to visually handicapped children is explained in relation to the school run by the Royal Victorian Institution for the Blind in Melbourne. A period of residential education may be needed for children with multiple impairment. Those whose handicap is primarily visual can usually live at home and have their education integrated with that of their normal peers. Home-based services and parent support systems for preschool and kindergarten age children are outlined. To be successful, they require sharing confidential medical and education information. The school provides a major input to a discussion group of all professionals dealing with such children. Information from the group includes the causes, and educational implications of visual handicap in Victorian children. The commonest pathologies are macular problems and congenital cataract.

  19. Characterizing Crowd Participation and Productivity of Foldit Through Web Scraping

    Science.gov (United States)

    2016-03-01

    emphasis toward creating a small but highly trained player subset provide a strong argument for a more productive CSSG over a more entertainment-focused...Foldit’s game design and emphasis toward creating a small but highly trained player subset provide a strong argument for a more productive CSSG over a...the score for a given puzzle. Aside from aesthetics , these visual changes also reinforce the game restraints to the player. The game also takes

  20. Visual Sedimentation

    OpenAIRE

    Huron, Samuel; Vuillemot, Romain; Fekete, Jean-Daniel

    2013-01-01

    International audience; We introduce Visual Sedimentation, a novel design metaphor for visualizing data streams directly inspired by the physical process of sedimentation. Visualizing data streams (e. g., Tweets, RSS, Emails) is challenging as incoming data arrive at unpredictable rates and have to remain readable. For data streams, clearly expressing chronological order while avoiding clutter, and keeping aging data visible, are important. The metaphor is drawn from the real-world sedimentat...

  1. Crowding and Cognitive Development: The Mediating Role of Maternal Responsiveness among 36-Month-Old Children

    Science.gov (United States)

    Evans, Gary W.; Ricciuti, Henry N.; Hope, Steven; Schoon, Ingrid; Bradley, Robert H.; Corwyn, Robert F.; Hazan, Cindy

    2010-01-01

    Residential crowding in both U.S. and U.K. samples of 36-month-old children is related concurrently to the Bracken scale, a standard index of early cognitive development skills including letter and color identification, shape recognition, and elementary numeric comprehension. In the U.S. sample, these effects also replicate prospectively.…

  2. How to Move in a Jostling Crowd The Art of Harnessing Random ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 10. How to Move in a Jostling Crowd The Art of Harnessing Random Motions. G S Ranganath. Research News Volume 1 Issue 10 October 1996 pp 84-86. Fulltext. Click here to view fulltext PDF. Permanent link:

  3. Geographic information system based noise study in crowded areas of Isfahan city in 2010-2011

    Directory of Open Access Journals (Sweden)

    Negar Jafari

    2015-01-01

    Conclusion: It can be concluded that as in the most cases the noise levels of Isfahan exceeded from the guideline values. This city is categorized in the noisy/crowded cities in Iran. Thus, noise pollution of Isfahan can be a serious problem and investigating its reasons is recommended.

  4. Paying out and Crowding out? The Globalisation of Higher Education. CEP Discussion Paper No. 1299

    Science.gov (United States)

    Machin, Stephen; Murphy, Richard

    2014-01-01

    We investigate the rapid influx of overseas students into UK higher education and the impact on the number of domestic students. Using administrative data since 1994/5, we find no evidence of crowd out of domestic undergraduate students and indications of increases in the domestic numbers of postgraduate students as overseas enrolments have grown.…

  5. Do monetary rewards crowd out intrinsic motivations of volunteers? Some empirical evidence for Italian volunteers

    OpenAIRE

    Damiano Fiorillo

    2009-01-01

    The paper studies the determinants of regular volunteering departing from previous literature on extrinsic and intrinsic motivations. It contributes to the literature investigating the role of monetary rewards to influence intrinsic motivation. Using a simple framework that allows me to study the effect of monetary rewards on intrinsic motivation, the paper shows, controlling for endogenous bias, that monetary rewards crowd-out intrinsic motivation.

  6. Effects of Crowding Combined with Mood on Working Memory Performance among College Students

    Science.gov (United States)

    Daniel, Lisa

    2012-01-01

    This study investigated the effects of crowding combined with mood on working memory performance among college students. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web…

  7. Average interradicular sites for miniscrew insertion: should dental crowding be considered?

    Directory of Open Access Journals (Sweden)

    Michele Tepedino

    Full Text Available ABSTRACT Objective: To define a map of interradicular spaces where miniscrew can be likely placed at a level covered by attached gingiva, and to assess if a correlation between crowding and availability of space exists. Methods: Panoramic radiographs and digital models of 40 patients were selected according to the inclusion criteria. Interradicular spaces were measured on panoramic radiographs, while tooth size-arch length discrepancy was assessed on digital models. Statistical analysis was performed to evaluate if interradicular spaces are influenced by the presence of crowding. Results: In the mandible, the most convenient sites for miniscrew insertion were in the spaces comprised between second molars and first premolars; in the maxilla, between first molars and second premolars as well as between canines and lateral incisors and between the two central incisors. The interradicular spaces between the maxillary canines and lateral incisors, and between mandibular first and second premolars revealed to be influenced by the presence of dental crowding. Conclusions: The average interradicular sites map hereby proposed can be used as a general guide for miniscrew insertion at the very beginning of orthodontic treatment planning. Then, the clinician should consider the amount of crowding: if this is large, the actual interradicular space in some areas might be significantly different from what reported on average. Individualized radiographs for every patient are still recommended.

  8. Extracting foreground ensemble features to detect abnormal crowd behavior in intelligent video-surveillance systems

    Science.gov (United States)

    Chan, Yi-Tung; Wang, Shuenn-Jyi; Tsai, Chung-Hsien

    2017-09-01

    Public safety is a matter of national security and people's livelihoods. In recent years, intelligent video-surveillance systems have become important active-protection systems. A surveillance system that provides early detection and threat assessment could protect people from crowd-related disasters and ensure public safety. Image processing is commonly used to extract features, e.g., people, from a surveillance video. However, little research has been conducted on the relationship between foreground detection and feature extraction. Most current video-surveillance research has been developed for restricted environments, in which the extracted features are limited by having information from a single foreground; they do not effectively represent the diversity of crowd behavior. This paper presents a general framework based on extracting ensemble features from the foreground of a surveillance video to analyze a crowd. The proposed method can flexibly integrate different foreground-detection technologies to adapt to various monitored environments. Furthermore, the extractable representative features depend on the heterogeneous foreground data. Finally, a classification algorithm is applied to these features to automatically model crowd behavior and distinguish an abnormal event from normal patterns. The experimental results demonstrate that the proposed method's performance is both comparable to that of state-of-the-art methods and satisfies the requirements of real-time applications.

  9. A Comparative Study of k-Nearest Neighbour Techniques in Crowd Simulation

    NARCIS (Netherlands)

    Vermeulen, J.; Hillebrand, A.; Geraerts, R.J.

    2017-01-01

    The k-nearest neighbour (kNN) problem appears in many different fields of computer science, such as computer animation and robotics. In crowd simulation, kNN queries are typically used by a collision-avoidance method to prevent unnecessary computations. Many different methods for finding these

  10. Motion Planning for Human Crowds: from Individuals to Groups of Virtual Characters

    NARCIS (Netherlands)

    Karamouzas, I.|info:eu-repo/dai/nl/304841269

    2012-01-01

    Virtual worlds, to become more lively and appealing, are typically populated by large crowds of virtual characters. One of the fundamental tasks that these characters have to perform is, on one hand, to plan their paths between different locations in the world and, on the other hand, to move toward

  11. Tenth Annual Interfaith Ramadan Iftar Draws Large Crowd to Sacramento Capitol

    National Research Council Canada - National Science Library

    Elaine Pasquini

    2013-01-01

    ... message to the rest of the world. Religion must be a unifier, not a divider. During his turn at the microphone, Assembly member Steve Fox tickled the crowd when he stated that he's Jewish and he was endorsed by the Los Angeles CAIR group and he won his election because of them.

  12. Macromolecular Crowding Studies of Amino Acids Using NMR Diffusion Measurements and Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Amninder S Virk

    2015-02-01

    Full Text Available Molecular crowding occurs when the total concentration of macromolecular species in a solution is so high that a considerable proportion of the volume is physically occupied and therefore not accessible to other molecules. This results in significant changes in the solution properties of the molecules in such systems. Macromolecular crowding is ubiquitous in biological systems due to the generally high intracellular protein concentrations. The major hindrance to understanding crowding is the lack of direct comparison of experimental data with theoretical or simulated data. Self-diffusion is sensitive to changes in the molecular weight and shape of the diffusing species, and the available diffusion space (i.e., diffusive obstruction. Consequently, diffusion measurements are a direct means for probing crowded systems including the self-association of molecules. In this work, nuclear magnetic resonance measurements of the self-diffusion of four amino acids (glycine, alanine, valine and phenylalanine up to their solubility limit in water were compared directly with molecular dynamics simulations. The experimental data were then analyzed using various models of aggregation and obstruction. Both experimental and simulated data revealed that the diffusion of both water and the amino acids were sensitive to the amino acid concentration. The direct comparison of the simulated and experimental data afforded greater insights into the aggregation and obstruction properties of each amino acid.

  13. Share the Crowdsensing Data with Local Crowd by V2V Communications

    Directory of Open Access Journals (Sweden)

    Chao Song

    2016-01-01

    Full Text Available With an increase in the number of mobile applications, the development of mobile crowdsensing systems has recently attracted significant attention from both academic researchers and industries. In mobile crowdsensing system, the remote cloud (or back-end server harvests all the crowdsensing data from the mobile devices, and the crowdsensing data can be uploaded immediately via 3G/4G. To reduce the cost and energy consumption, many academic researchers and industries investigate the way of mobile data offloading. Due to the sparse distribution of the WiFi APs, offloading the crowdsensing data is often delayed. In this paper, compared with offloading data via WiFi APs, we investigate the communication and sharing of crowdsensing data by vehicles near the event (such as a pothole on the road, termed as a local crowd. In such crowd, a vehicle can transmit the data to each other by vehicle-to-vehicle (V2V communication. The crowd-based approach has a lower delay than the offloading-based approach, by considering the quality of truth discovery. We define a utility function related to the crowdsensing data shared by the local crowd in order to quantify the trade-off between the quality of the truth discovery and the user satisfaction. Our extensional simulations verify the effectiveness of our proposed schemes.

  14. Crowd-induced vibrations of a steel footbridge in Reykjavík

    DEFF Research Database (Denmark)

    Ingólfsson, Einar Thór; Gudmundsson, G. V.; Živanović, S.

    2012-01-01

    in relation to the results obtained from a controlled crowd test on a steel footbridge in Reykjavik, Iceland. A systematic quantification of the measured vibration response is carried out and the results are presented statistically through their probability distributions. Finally, testimonies from...

  15. Continuum modelling of pedestrian flows - Part 2: Sensitivity analysis featuring crowd movement phenomena

    Science.gov (United States)

    Duives, Dorine C.; Daamen, Winnie; Hoogendoorn, Serge P.

    2016-04-01

    In recent years numerous pedestrian simulation tools have been developed that can support crowd managers and government officials in their tasks. New technologies to monitor pedestrian flows are in dire need of models that allow for rapid state-estimation. Many contemporary pedestrian simulation tools model the movements of pedestrians at a microscopic level, which does not provide an exact solution. Macroscopic models capture the fundamental characteristics of the traffic state at a more aggregate level, and generally have a closed form solution which is necessary for rapid state estimation for traffic management purposes. This contribution presents a next step in the calibration and validation of the macroscopic continuum model detailed in Hoogendoorn et al. (2014). The influence of global and local route choice on the development of crowd movement phenomena, such as dissipation, lane-formation and stripe-formation, is studied. This study shows that most self-organization phenomena and behavioural trends only develop under very specific conditions, and as such can only be simulated using specific parameter sets. Moreover, all crowd movement phenomena can be reproduced by means of the continuum model using one parameter set. This study concludes that the incorporation of local route choice behaviour and the balancing of the aptitude of pedestrians with respect to their own class and other classes are both essential in the correct prediction of crowd movement dynamics.

  16. Tracking individuals in surveillance video of a high-density crowd

    NARCIS (Netherlands)

    Hu, N.; Bouma, H.; Worring, M.

    2012-01-01

    Video cameras are widely used for monitoring public areas, such as train stations, airports and shopping centers. When crowds are dense, automatically tracking individuals becomes a challenging task. We propose a new tracker which employs a particle filter tracking framework, where the state

  17. Interactive Modeling, Simulation and Control of Large-Scale Crowds and Traffic

    Science.gov (United States)

    Lin, Ming C.; Guy, Stephen; Narain, Rahul; Sewall, Jason; Patil, Sachin; Chhugani, Jatin; Golas, Abhinav; van den Berg, Jur; Curtis, Sean; Wilkie, David; Merrell, Paul; Kim, Changkyu; Satish, Nadathur; Dubey, Pradeep; Manocha, Dinesh

    We survey some of our recent work on interactive modeling, simulation, and control of large-scale crowds and traffic for urban scenes. The driving applications of our work include real-time simulation for computer games, virtual environments, and avatar-based online 3D social networks. We also present some preliminary results and proof-of-concept demonstrations.

  18. Soft Regulation with Crowd Recommendation: Coordinating Self-Interested Agents in Sociotechnical Systems under Imperfect Information.

    Science.gov (United States)

    Luo, Yu; Iyengar, Garud; Venkatasubramanian, Venkat

    2016-01-01

    Regulating emerging industries is challenging, even controversial at times. Under-regulation can result in safety threats to plant personnel, surrounding communities, and the environment. Over-regulation may hinder innovation, progress, and economic growth. Since one typically has limited understanding of, and experience with, the novel technology in practice, it is difficult to accomplish a properly balanced regulation. In this work, we propose a control and coordination policy called soft regulation that attempts to strike the right balance and create a collective learning environment. In soft regulation mechanism, individual agents can accept, reject, or partially accept the regulator's recommendation. This non-intrusive coordination does not interrupt normal operations. The extent to which an agent accepts the recommendation is mediated by a confidence level (from 0 to 100%). Among all possible recommendation methods, we investigate two in particular: the best recommendation wherein the regulator is completely informed and the crowd recommendation wherein the regulator collects the crowd's average and recommends that value. We show by analysis and simulations that soft regulation with crowd recommendation performs well. It converges to optimum, and is as good as the best recommendation for a wide range of confidence levels. This work sheds a new theoretical perspective on the concept of the wisdom of crowds.

  19. Analytical Modelling of the Spread of Disease in Confined and Crowded Spaces

    Science.gov (United States)

    Goscé, Lara; Barton, David A. W.; Johansson, Anders

    2014-05-01

    Since 1927 and until recently, most models describing the spread of disease have been of compartmental type, based on the assumption that populations are homogeneous and well-mixed. Recent models have utilised agent-based models and complex networks to explicitly study heterogeneous interaction patterns, but this leads to an increasing computational complexity. Compartmental models are appealing because of their simplicity, but their parameters, especially the transmission rate, are complex and depend on a number of factors, which makes it hard to predict how a change of a single environmental, demographic, or epidemiological factor will affect the population. Therefore, in this contribution we propose a middle ground, utilising crowd-behaviour research to improve compartmental models in crowded situations. We show how both the rate of infection as well as the walking speed depend on the local crowd density around an infected individual. The combined effect is that the rate of infection at a population scale has an analytically tractable non-linear dependency on crowd density. We model the spread of a hypothetical disease in a corridor and compare our new model with a typical compartmental model, which highlights the regime in which current models may not produce credible results.

  20. Mindless thugs running riot? Mainstream, alternative and online media representations of football crowd violence

    NARCIS (Netherlands)

    Spaaij, R.

    2011-01-01

    This article examines the nature of media coverage of football (soccer) crowd violence in three European countries (England, The Netherlands and Spain). It presents an analytic framework that draws on etic (outsider) and emic (insider) perspectives, and illustrates how each perspective is