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Sample records for sustained attention dots

  1. Sustained Attention Ability Affects Simple Picture Naming

    Directory of Open Access Journals (Sweden)

    Suzanne R. Jongman

    2017-07-01

    Full Text Available Sustained attention has previously been shown as a requirement for language production. However, this is mostly evident for difficult conditions, such as a dual-task situation. The current study provides corroborating evidence that this relationship holds even for simple picture naming. Sustained attention ability, indexed both by participants’ reaction times and individuals’ hit rate (the proportion of correctly detected targets on a digit discrimination task, correlated with picture naming latencies. Individuals with poor sustained attention were consistently slower and their RT distributions were more positively skewed when naming pictures compared to individuals with better sustained attention. Additionally, the need to sustain attention was manipulated by changing the speed of stimulus presentation. Research has suggested that fast event rates tax sustained attention resources to a larger degree than slow event rates. However, in this study the fast event rate did not result in increased difficulty, neither for the picture naming task nor for the sustained attention task. Instead, the results point to a speed-accuracy trade-off in the sustained attention task (lower accuracy but faster responses in the fast than in the slow event rate, and to a benefit for faster rates in the picture naming task (shorter naming latencies with no difference in accuracy. Performance on both tasks was largely comparable, supporting previous findings that sustained attention is called upon during language production.

  2. Chewing and Attention: A Positive Effect on Sustained Attention

    OpenAIRE

    Yoshiyuki Hirano; Minoru Onozuka

    2015-01-01

    Chewing is crushing food not only to aid swallowing and digestion, but also to help stress relief and regulate cognitive function, especially in attention. It is well known that chewing gum is used for sleepiness prevention during work, learning, and driving, suggesting a link between chewing and sustained attention. We hypothesized that chewing elevates attention and/or alertness, leading to improvements in cognitive performance. We carried out a systematic review of the PubMed database. We ...

  3. Chewing and Attention: A Positive Effect on Sustained Attention

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Hirano

    2015-01-01

    Full Text Available Chewing is crushing food not only to aid swallowing and digestion, but also to help stress relief and regulate cognitive function, especially in attention. It is well known that chewing gum is used for sleepiness prevention during work, learning, and driving, suggesting a link between chewing and sustained attention. We hypothesized that chewing elevates attention and/or alertness, leading to improvements in cognitive performance. We carried out a systematic review of the PubMed database. We inspected the attributes of effects on attention in studies investigating the effects of chewing on attention or alertness conducted with pre-post design in healthy subjects, except elderly. We identified 151 references, 22 of which were included: 14 (64% showed positive attributes of effects on attention, 1 (5% showed negative attributes of effects on attention, 5 (23% showed both positive and negative attributes of effects on attention, and 2 (9% showed no significant attributes of effects on attention. Thus, positive attributes of effects of chewing on attention, especially on sustained attention, were shown in over half of the reports. These effects also appeared with improvement in mood and stress relief and were influenced by time-on-task effect. Further studies are needed, but chewing could be useful for modifying cognitive function.

  4. Chewing and attention: a positive effect on sustained attention.

    Science.gov (United States)

    Hirano, Yoshiyuki; Onozuka, Minoru

    2015-01-01

    Chewing is crushing food not only to aid swallowing and digestion, but also to help stress relief and regulate cognitive function, especially in attention. It is well known that chewing gum is used for sleepiness prevention during work, learning, and driving, suggesting a link between chewing and sustained attention. We hypothesized that chewing elevates attention and/or alertness, leading to improvements in cognitive performance. We carried out a systematic review of the PubMed database. We inspected the attributes of effects on attention in studies investigating the effects of chewing on attention or alertness conducted with pre-post design in healthy subjects, except elderly. We identified 151 references, 22 of which were included: 14 (64%) showed positive attributes of effects on attention, 1 (5%) showed negative attributes of effects on attention, 5 (23%) showed both positive and negative attributes of effects on attention, and 2 (9%) showed no significant attributes of effects on attention. Thus, positive attributes of effects of chewing on attention, especially on sustained attention, were shown in over half of the reports. These effects also appeared with improvement in mood and stress relief and were influenced by time-on-task effect. Further studies are needed, but chewing could be useful for modifying cognitive function.

  5. Touchscreen Sustained Attention Task (SAT) for Rats.

    Science.gov (United States)

    Bangasser, Debra A; Wicks, Brittany; Waxler, David E; Eck, Samantha R

    2017-09-15

    Sustained attention is the ability to monitor intermittent and unpredictable events over a prolonged period of time. This attentional process subserves other aspects of cognition and is disrupted in certain neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Thus, it is clinically important to identify mechanisms that impair and improve sustained attention. Such mechanisms are often first discovered using rodent models. Therefore, several behavior procedures for testing aspects of sustained attention have been developed for rodents. One, first described by McGaughy and Sarter (1995), called the sustained attention task (SAT), trains rats to distinguish between signal (i.e., brief light presentation) and non-signal trials. The signals are short and thus require careful attention to be perceived. Attentional demands can be increased further by introducing a distractor (e.g., flashing houselight). We have modified this task for touchscreen operant chambers, which are configured with a touchscreen on one wall that can present stimuli and record responses. Here we detail our protocol for SAT in touchscreen chambers. Additionally, we present standard measures of performance in male and female Sprague-Dawley rats. Comparable performance on this task in both sexes highlights its use for attention studies, especially as more researchers are including female rodents in their experimental design. Moreover, the easy implementation of SAT for the increasingly popular touchscreen chambers increases its utility.

  6. Sustained attention in psychosis: Neuroimaging findings

    Science.gov (United States)

    Sepede, Gianna; Spano, Maria Chiara; Lorusso, Marco; De Berardis, Domenico; Salerno, Rosa Maria; Di Giannantonio, Massimo; Gambi, Francesco

    2014-01-01

    To provide a systematic review of scientific literature on functional magnetic resonance imaging (fMRI) studies on sustained attention in psychosis. We searched PubMed to identify fMRI studies pertaining sustained attention in both affective and non-affective psychosis. Only studies conducted on adult patients using a sustained attention task during fMRI scanning were included in the final review. The search was conducted on September 10th, 2013. 15 fMRI studies met our inclusion criteria: 12 studies were focused on Schizophrenia and 3 on Bipolar Disorder Type I (BDI). Only half of the Schizophrenia studies and two of the BDI studies reported behavioral abnormalities, but all of them evidenced significant functional differences in brain regions related to the sustained attention system. Altered functioning of the insula was found in both Schizophrenia and BDI, and therefore proposed as a candidate trait marker for psychosis in general. On the other hand, other brain regions were differently impaired in affective and non-affective psychosis: alterations of cingulate cortex and thalamus seemed to be more common in Schizophrenia and amygdala dysfunctions in BDI. Neural correlates of sustained attention seem to be of great interest in the study of psychosis, highlighting differences and similarities between Schizophrenia and BDI. PMID:24976929

  7. Neuropsychological correlates of sustained attention in schizophrenia.

    Science.gov (United States)

    Chen, E Y; Lam, L C; Chen, R Y; Nguyen, D G; Chan, C K; Wilkins, A J

    1997-04-11

    We employed a simple and relatively undemanding task of monotone counting for the assessment of sustained attention in schizophrenic patients. The monotone counting task has been validated neuropsychologically and is particularly sensitive to right prefrontal lesions. We compared the performance of schizophrenic patients with age- and education-matched controls. We then explored the extent to which a range of commonly employed neuropsychological tasks in schizophrenia research are related to attentional impairment as measured in this way. Monotone counting performance was found to be correlated with digit span (WAIS-R-HK), information (WAIS-R-HK), comprehension (WAIS-R-HK), logical memory (immediate recall) (Weschler Memory Scale, WMS), and visual reproduction (WMS). Multiple regression analysis also identified visual reproduction, digit span and comprehension as significant predictors of attention performance. In contrast, logical memory (delay recall) (WMS), similarity (WAIS-R-HK), semantic fluency, and Wisconsin Card Sorting Test (perseverative errors) were not correlated with attention. In addition, no significant correlation between sustained attention and symptoms was found. These findings are discussed in the context of a weakly modular cognitive system where attentional impairment may contribute selectively to a range of other cognitive deficits.

  8. Effect of attention control on sustained attention during induced anxiety.

    Science.gov (United States)

    Grillon, Christian; Robinson, Oliver J; Mathur, Ambika; Ernst, Monique

    2016-01-01

    Anxiety has wide-reaching and complex effects on cognitive performance. Although it can intrude on cognition and interfere with performance, it can also facilitate information processing and behavioural responses. In a previous study, we showed that anxiety induced by threat of shock facilitates performance on the Sustained Attention to Response Task, a vigilance test, which probes response inhibition to infrequent nogo stimuli. The present study sought to identify factors that may have contributed to such improved performance, including on- and off-task thinking (assessed with thought probes) and individual differences in attention control, as measured with the Attention Control Scale. Replicating our prior finding, we showed that shock threat significantly reduced errors of commission on the nogo trials. However, we extended this finding in demonstrating that this effect was driven by subjects with low attention control. We therefore confirm that anxiety increases inhibitory control of prepotent responses--a mechanism which is adaptive under threat--and show that this effect is greater in those who rely more upon such prepotent responding, i.e., those with low attentional control.

  9. Recent theoretical, neural, and clinical advances in sustained attention research.

    Science.gov (United States)

    Fortenbaugh, Francesca C; DeGutis, Joseph; Esterman, Michael

    2017-05-01

    Models of attention often distinguish among attention subtypes, with classic models separating orienting, switching, and sustaining functions. Compared with other forms of attention, the neurophysiological basis of sustaining attention has received far less notice, yet it is known that momentary failures of sustained attention can have far-ranging negative effects in healthy individuals, and lasting sustained attention deficits are pervasive in clinical populations. In recent years, however, there has been increased interest in characterizing moment-to-moment fluctuations in sustained attention, in addition to the overall vigilance decrement, and understanding how these neurocognitive systems change over the life span and across various clinical populations. The use of novel neuroimaging paradigms and statistical approaches has allowed for better characterization of the neural networks supporting sustained attention and has highlighted dynamic interactions within and across multiple distributed networks that predict behavioral performance. These advances have also provided potential biomarkers to identify individuals with sustained attention deficits. These findings have led to new theoretical models explaining why sustaining focused attention is a challenge for individuals and form the basis for the next generation of sustained attention research, which seeks to accurately diagnose and develop theoretically driven treatments for sustained attention deficits that affect a variety of clinical populations. © 2017 New York Academy of Sciences.

  10. Vigilance and Sustained Attention in Children and Adults with ADHD

    Science.gov (United States)

    Tucha, Lara; Tucha, Oliver; Walitza, Susanne; Sontag, Thomas A.; Laufkotter, Rainer; Linder, Martin; Lange, Klaus W.

    2009-01-01

    Objective: The present article tests the hypothesis of a sustained attention deficit in children and adults suffering from ADHD. Method: Vigilance and sustained attention of 52 children with ADHD and 38 adults with ADHD were assessed using a computerized vigilance task. Furthermore, the attentional performance of healthy children (N = 52) and…

  11. Education for Sustainable Development: Connecting the Dots for Sustainability

    Science.gov (United States)

    Gokool-Ramdoo, Sushita; Rumjaun, Anwar Bhai

    2017-01-01

    Critical pedagogy, practitioner experience and a regulatory perspective are employed to scrutinize the notion of Education for Sustainable Development (ESD) as it occurs in the literature. They promote understanding of the challenges impeding the completion of unfinished ESD businesses. In response to practitioner-expressed needs, this paper…

  12. Self-Sustaining Dynamical Nuclear Polarization Oscillations in Quantum Dots

    DEFF Research Database (Denmark)

    Rudner, Mark Spencer; Levitov, Leonid

    2013-01-01

    a minimal albeit realistic model of coupled electron and nuclear spin dynamics which supports self-sustained oscillations. Our mechanism relies on a nuclear spin analog of the tunneling magnetoresistance phenomenon (spin-dependent tunneling rates in the presence of an inhomogeneous Overhauser field......Early experiments on spin-blockaded double quantum dots revealed robust, large-amplitude current oscillations in the presence of a static (dc) source-drain bias. Despite experimental evidence implicating dynamical nuclear polarization, the mechanism has remained a mystery. Here we introduce......) and nuclear spin diffusion, which governs dynamics of the spatial profile of nuclear polarization. The proposed framework naturally explains the differences in phenomenology between vertical and lateral quantum dot structures as well as the extremely long oscillation periods....

  13. Sustained attention in language production: An individual differences investigation

    NARCIS (Netherlands)

    Jongman, S.R.; Roelofs, A.P.A.; Meyer, A.S.

    2015-01-01

    Whereas it has long been assumed that most linguistic processes underlying language production happen automatically, accumulating evidence suggests that these processes do require some form of attention. Here we investigated the contribution of sustained attention: the ability to maintain alertness

  14. [Effects of distractors on sustained attention in children with attention-deficit hyperactive disorder].

    Science.gov (United States)

    Xu, Yan; Zhou, Xiao-lin; Wang, Yu-feng

    2004-01-01

    Using an experimental design combining the sustained attention task (CPT, SART) and the flanker task, we investigated: 1) whether children with attention-deficit hyperactive disorder (ADHD) have deficits in their sustained attention; 2) whether distractors have different effects on response to targets at different sustained attention levels; 3) whether different subtypes of ADHD children show different patterns in sustained attention. Subjects were recruited from elementary school (Grade 2 - 6). Twenty seven ADHD children (23 male, 4 female) and 29 normal controls (24 male, 5 female) were matched by IQ and age. The cognitive experiment measuring reaction times and error rates was conducted on a computer using DMDX software. ADHD and normal children's performance in sustained attention and the effect of distractors were analyzed, and the results of subtypes of ADHD were compared. ADHD children and normal children did not show significant differences in error rates in their response to dominant (non-attentional) item. However, distractors impaired ADHD children's response to targets. ADHD children also showed more errors than normal children in the sustained attention task, but compared with the non-distractor condition, distractors facilitated their response. ADHD children have deficits in their sustained attention, reflecting the deficits in brain development. More importantly, this study found that the effects of distractors in sustained attention can be dissociated according to the level of demand on sustained attention: distractors interfered with responses to targets when the demand on sustained attention was low, and they facilitated responses to targets when the demand on sustained attention was high. There were no significant differences between ADHD-inattentive type and ADHD-combined type in their deficits in sustained attention.

  15. Chewing and Attention: A Positive Effect on Sustained Attention

    National Research Council Canada - National Science Library

    Hirano, Yoshiyuki; Onozuka, Minoru

    2015-01-01

    .... These findings support the concept that chewing is strongly associated with cognitive function such as learning and memory and keeping and increasing attention [5]. This relationship between chewing and cognitive functions was empirically estimated a long time ago. In 1939, Hollingworth [6] reported that chewing increased relaxation and the performance of cognitive ...

  16. ERP characterization of sustained attention effects in visual lexical categorization.

    Directory of Open Access Journals (Sweden)

    Clara D Martin

    Full Text Available As our understanding of the basic processes underlying reading is growing, the key role played by attention in this process becomes evident. Two research topics are of particular interest in this domain: (1 it is still undetermined whether sustained attention affects lexical decision tasks; (2 the influence of attention on early visual processing (i.e., before orthographic or lexico-semantic processing stages remains largely under-specified. Here we investigated early perceptual modulations by sustained attention using an ERP paradigm adapted from Thierry et al. [1]. Participants had to decide whether visual stimuli presented in pairs pertained to a pre-specified category (lexical categorization focus on word or pseudoword pairs. Depending on the lexical category of the first item of a pair, participants either needed to fully process the second item (hold condition or could release their attention and make a decision without full processing of the second item (release condition. The P1 peak was unaffected by sustained attention. The N1 was delayed and reduced after the second item of a pair when participants released their attention. Release of sustained attention also reduced a P3 wave elicited by the first item of a pair and abolished the P3 wave elicited by the second. Our results are consistent with differential effects of sustained attention on early processing stages and working memory. Sustained attention modulated early processing stages during a lexical decision task without inhibiting the process of stimulus integration. On the contrary, working memory involvement/updating was highly dependent upon the allocation of sustained attention. Moreover, the influence of sustained attention on both early and late cognitive processes was independent of lexical categorization focus.

  17. Incorporating sustainability into TxDOT's transportation decision making : summary of work performed, methods used, and results achieved.

    Science.gov (United States)

    2011-02-01

    This report summarizes the work performed in Fiscal Year (FY) 2009 and 2010 under TxDOT : Implementation Project 5-5541-01 Regional Workshops on Sustainability Enhancement : Tool. TxDOT Research Project 0-5541, Developing Sustainable Tra...

  18. Exploring the relationship between boredom and sustained attention.

    Science.gov (United States)

    Malkovsky, Ela; Merrifield, Colleen; Goldberg, Yael; Danckert, James

    2012-08-01

    Boredom is a common experience, prevalent in neurological and psychiatric populations, yet its cognitive characteristics remain poorly understood. We explored the relationship between boredom proneness, sustained attention and adult symptoms of attention deficit hyperactivity disorder (ADHD). The results showed that high boredom-prone individuals (HBP) performed poorly on measures of sustained attention and showed increased symptoms of ADHD and depression. The results also showed that HBP individuals can be characterised as either apathetic-in which the individual is unconcerned with his/her environment, or as agitated-in which the individual is motivated to engage in meaningful activities, although attempts to do so fail to satisfy. Apathetic boredom proneness was associated with attention lapses, whereas agitated boredom proneness was associated with decreased sensitivity to errors of sustained attention, and increased symptoms of adult ADHD. Our results suggest there is a complex relationship between attention and boredom proneness.

  19. European Sustainable Construction Regulation : Homogeneity and Attention

    NARCIS (Netherlands)

    Van der Heijden, J.; Van Bueren, E.M.

    2011-01-01

    Understanding the negative impact of the construction industry and the built environment on the ecological environment, the European Commission (EC) aims to harmonise and improve sustainable construction regulatory frameworks in Member States of the European Union. This paper discusses the topics of

  20. Sustained attention ability in schizophrenia: Investigation of conflict monitoring mechanisms.

    Science.gov (United States)

    Hoonakker, Marc; Doignon-Camus, Nadège; Marques-Carneiro, José Eduardo; Bonnefond, Anne

    2017-09-01

    The main goal of the current study was to assess, with a time-on-task approach, sustained attention ability in schizophrenia, and to investigate conflict monitoring underlying this ability. Behavioral and event-related potentials data (N2 and P3a amplitudes) were recorded in a long-lasting sustained attention Go/NoGo task (sustained attention to response task, SART), over a period of 30min, in 29 patients with schizophrenia and 29 pair-matched healthy subjects. Our results revealed spared sustained attention ability in patients throughout the task. Impairment of conflict detection (N2) in patients was particularly significant at the end of the task. Furthermore, both schizophrenia and healthy subjects exhibited a decline in conflict detection from the beginning to the middle of the task. Whereas controls' conflict detection recovered in the last part of the task, patients' did not, suggesting a deficit in recovery processes reflecting a lack of additional resources sustained attention Go/NoGo task. Conflict resolution (P3a) was preserved throughout the task in both groups. Conflict monitoring processes are increasingly impaired in schizophrenia during a long-lasting sustained attention Go/NoGo task. This impairment at the end of the task may rely on deficit in recovery processes, rather than a deficit in conflict detection per se in schizophrenia. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  1. Sustained and Focused Attention Deficits in Adult ADHD

    Science.gov (United States)

    Marchetta, Natalie D. J.; Hurks, Petra P. M.; De Sonneville, Leo M. J.; Krabbendam, Lydia; Jolles, Jelle

    2008-01-01

    Objective: To examine the specificity of deficits in focused attention and sustained attention in adults with ADHD and to evaluate the effect of comorbidity. Method: Twenty-eight adults with ADHD without comorbidity were compared with 28 ADHD outpatients with comorbidity. Two control groups were used: 68 adults referred for ADHD but with another…

  2. Lesion Neuroanatomy of the Sustained Attention to Response Task

    Science.gov (United States)

    Molenberghs, Pascal; Gillebert, Celine R.; Schoofs, Hanne; Dupont, Patrick; Peeters, Ronald; Vandenberghe, Rik

    2009-01-01

    The Sustained Attention to Response task is a classical neuropsychological test that has been used by many centres to characterize the attentional deficits in traumatic brain injury, ADHD, autism and other disorders. During the SART a random series of digits 1-9 is presented repeatedly and subjects have to respond to each digit (go trial) except…

  3. The effect of methylphenidate on sustained attention among adolescents with attention-deficit hyperactivity disorder.

    Science.gov (United States)

    Lufi, Dubi; Bassin-Savion, Shiry; Rubel, Lilach

    2015-01-01

    Twenty-seven adolescents diagnosed as having attention-deficit hyperactivity disorder (ADHD) were tested twice with a computerized MATH-CPT (mathematics continuous performance test). In one administration, the participants took medication (methylphenidate, MPH) 1.5 hr before being tested. In another administration, the MATH-CPT was administered without the medication. Treatment with MPH improved the "overall attention level" and in measures of "reaction time" and "impulsivity." MPH did not improve the performance in the four measures of sustained attention. Knowing that treatment with MPH does not improve sustained attention can be helpful in reaching a decision of whether or not a child should be treated with MPH.

  4. The Problem of Attention Management in Innovation for Sustainability

    OpenAIRE

    Brooks, H.

    1995-01-01

    The problem of attention management is one of the main challenges in the transition to environmentally sustainable development paths. The design principle that attention is scarce is very different from a principle of "more information is better". This paper discusses the issue of "attention management" in various contexts, including R&D and innovation management, scientific communities, and technology policy. The question arising from this analysis is whether dependence on personal contact, ...

  5. The importance of sustained attention in early Alzheimer's disease.

    Science.gov (United States)

    Huntley, Jonathan D; Hampshire, Adam; Bor, Daniel; Owen, Adrian M; Howard, Robert J

    2017-08-01

    There is conflicting evidence regarding impairment of sustained attention in early Alzheimer's disease (AD). We examine whether sustained attention is impaired and predicts deficits in other cognitive domains in early AD. Fifty-one patients with early AD (MMSE > 18) and 15 healthy elderly controls were recruited. The sustained attention to response task (SART) was used to assess sustained attention. A subset of 25 patients also performed tasks assessing general cognitive function (ADAS-Cog), episodic memory (Logical memory scale, Paired Associates Learning), executive function (verbal fluency, grammatical reasoning) and working memory (digit and spatial span). AD patients were significantly impaired on the SART compared to healthy controls (total error β = 19.75, p = 0.027). SART errors significantly correlated with MMSE score (Spearman's rho = -0.338, p = 0.015) and significantly predicted deficits in ADAS-Cog (β = 0.14, p = 0.004). Patients with early AD have significant deficits in sustained attention, as measured using the SART. This may impair performance on general cognitive testing, and therefore should be taken into account during clinical assessment, and everyday management of individuals with early AD. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Sustained attention in adult ADHD : time-on-task effects of various measures of attention

    NARCIS (Netherlands)

    Tucha, Lara; Fuermaier, Anselm B.M.; Koerts, Janneke; Buggenthin, Rieka; Aschenbrenner, Steffen; Weisbrod, Matthias; Thome, Johannes; Lange, Klaus W.; Tucha, Oliver

    Neuropsychological research on adults with ADHD showed deficits in various aspects of attention. However, the majority of studies failed to explore the change of performance over time, so-called time-on-task effects. As a consequence, little is known about sustained attention performance of adults

  7. Positive valence music restores executive control over sustained attention.

    Science.gov (United States)

    Baldwin, Carryl L; Lewis, Bridget A

    2017-01-01

    Music sometimes improves performance in sustained attention tasks. But the type of music employed in previous investigations has varied considerably, which can account for equivocal results. Progress has been hampered by lack of a systematic database of music varying in key characteristics like tempo and valence. The aims of this study were to establish a database of popular music varying along the dimensions of tempo and valence and to examine the impact of music varying along these dimensions on restoring attentional resources following performance of a sustained attention to response task (SART) vigil. Sixty-nine participants rated popular musical selections that varied in valence and tempo to establish a database of four musical types: fast tempo positive valence, fast tempo negative valence, slow tempo positive valence, and slow tempo negative valence. A second group of 89 participants performed two blocks of the SART task interspersed with either no break or a rest break consisting of 1 of the 4 types of music or silence. Presenting positive valence music (particularly of slow tempo) during an intermission between two successive blocks of the SART significantly decreased miss rates relative to negative valence music or silence. Results support an attentional restoration theory of the impact of music on sustained attention, rather than arousal theory and demonstrate a means of restoring sustained attention. Further, the results establish the validity of a music database that will facilitate further investigations of the impact of music on performance.

  8. Incorporating sustainability into TxDOT's transportation decision-making : interactive workshop

    Science.gov (United States)

    2010-01-01

    The workshop is intended for new and experienced technical staff in TxDOT headquarters, district, and area offices to better understand how sustainability performance measures can be used at the sketch-planning level of project consideration. The wor...

  9. Sustained Attention in Real Classroom Settings: An EEG Study

    Directory of Open Access Journals (Sweden)

    Li-Wei Ko

    2017-07-01

    Full Text Available Sustained attention is a process that enables the maintenance of response persistence and continuous effort over extended periods of time. Performing attention-related tasks in real life involves the need to ignore a variety of distractions and inhibit attention shifts to irrelevant activities. This study investigates electroencephalography (EEG spectral changes during a sustained attention task within a real classroom environment. Eighteen healthy students were instructed to recognize as fast as possible special visual targets that were displayed during regular university lectures. Sorting their EEG spectra with respect to response times, which indicated the level of visual alertness to randomly introduced visual stimuli, revealed significant changes in the brain oscillation patterns. The results of power-frequency analysis demonstrated a relationship between variations in the EEG spectral dynamics and impaired performance in the sustained attention task. Across subjects and sessions, prolongation of the response time was preceded by an increase in the delta and theta EEG powers over the occipital region, and decrease in the beta power over the occipital and temporal regions. Meanwhile, implementation of the complex attention task paradigm into a real-world classroom setting makes it possible to investigate specific mutual links between brain activities and factors that cause impaired behavioral performance, such as development and manifestation of classroom mental fatigue. The findings of the study set a basis for developing a system capable of estimating the level of visual attention during real classroom activities by monitoring changes in the EEG spectra.

  10. Sustained attention and frailty in the older adult population.

    Science.gov (United States)

    O'Halloran, Aisling M; Finucane, Ciaran; Savva, George M; Robertson, Ian H; Kenny, Rose Anne

    2014-03-01

    We investigated whether sustained attention performance and variability were associated with prefrailty and frailty in the older adult population. A total of 4,317 participants aged 50 years and over from the Irish Longitudinal Study on Ageing (TILDA) completed a comprehensive health assessment. Frailty was defined by low gait speed, low grip strength, unintentional weight loss, self-reported exhaustion, and low physical activity. Scores of greater than or equal to 3, 1-2, and 0 indicated that participants were frail, prefrail, and nonfrail, respectively. Multinomial logistic regression computed associations between frailty state and measures of performance and variability on the Sustained Attention to Response Task (SART). Cognitive processing speed and executive function were also measured. Mean reaction time (RT; odds ratio [OR] = 1.13, p attention (OR = 1.11, p attention performance and variability were associated with prefrailty and frailty in the older adult population and may represent a novel, objective, and modifiable cognitive marker of frailty progression.

  11. Sustained attention, selective attention and cognitive control in deaf and hearing children.

    Science.gov (United States)

    Dye, Matthew W G; Hauser, Peter C

    2014-03-01

    Deaf children have been characterized as being impulsive, distractible, and unable to sustain attention. However, past research has tested deaf children born to hearing parents who are likely to have experienced language delays. The purpose of this study was to determine whether an absence of auditory input modulates attentional problems in deaf children with no delayed exposure to language. Two versions of a continuous performance test were administered to 37 deaf children born to Deaf parents and 60 hearing children, all aged 6-13 years. A vigilance task was used to measure sustained attention over the course of several minutes, and a distractibility test provided a measure of the ability to ignore task irrelevant information - selective attention. Both tasks provided assessments of cognitive control through analysis of commission errors. The deaf and hearing children did not differ on measures of sustained attention. However, younger deaf children were more distracted by task-irrelevant information in their peripheral visual field, and deaf children produced a higher number of commission errors in the selective attention task. It is argued that this is not likely to be an effect of audition on cognitive processing, but may rather reflect difficulty in endogenous control of reallocated visual attention resources stemming from early profound deafness. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Media multitasking and behavioral measures of sustained attention.

    Science.gov (United States)

    Ralph, Brandon C W; Thomson, David R; Seli, Paul; Carriere, Jonathan S A; Smilek, Daniel

    2015-02-01

    In a series of four studies, self-reported media multitasking (using the media multitasking index; MMI) and general sustained-attention ability, through performance on three sustained-attention tasks: the metronome response task (MRT), the sustained-attention-to-response task (SART), and a vigilance task (here, a modified version of the SART). In Study 1, we found that higher reports of media multitasking were associated with increased response variability (i.e., poor performance) on the MRT. However, in Study 2, no association between reported media multitasking and performance on the SART was observed. These findings were replicated in Studies 3a and 3b, in which we again assessed the relation between media multitasking and performance on both the MRT and SART in two large online samples. Finally, in Study 4, using a large online sample, we tested whether media multitasking was associated with performance on a vigilance task. Although standard vigilance decrements were observed in both sensitivity (A') and response times, media multitasking was not associated with the size of these decrements, nor was media multitasking associated with overall performance, in terms of either sensitivity or response times. Taken together, the results of the studies reported here failed to demonstrate a relation between habitual engagement in media multitasking in everyday life and a general deficit in sustained-attention processes.

  13. The Influence of Caffeine on Sustained Attention: An ERP study

    NARCIS (Netherlands)

    Lorist, MM; Snel, J; De Ruiter, MB; Ruijter, J

    The present study investigated the effects of caffeine on sustained attention by measuring concentration and fatigue. Event-related potentials (ERPs) and behavioral measures were recorded from 12 participants who worked continuously for approximately 10 min in a self-paced reaction task under

  14. Sustained attention assessment of narcoleptic patients: Two case reports

    Directory of Open Access Journals (Sweden)

    Mirleny Moraes

    Full Text Available Abstract Narcolepsy is a sleep disorder characterized by uncontrollable REM sleep attacks which alter the patients wake state and can lead to difficulties in attention aspects, such as maintaining attention when performing activities or tasks. This study aimed to evaluate sustained attention performance of two narcoleptic patients on the d2 Test, Epworth Sleepiness Scale (ESS, Pittsburgh Sleep Quality Index (PSQI and Hamilton Rating Scale for Depression (HAM-D. Results showed that the maintenance of attention was associated with a slowing of the target symbols processing function in visual scanning with accuracy in task performance. A high degree of excessive sleepiness was observed, along with mild and moderate degrees of depressive signs and symptoms. One subject also presented with a nocturnal sleep disorder which could represent an important factor affecting attentional and affective capacity.

  15. Simultanagnosia: a defect of sustained attention yields insights on visual information processing.

    Science.gov (United States)

    Rizzo, M; Robin, D A

    1990-03-01

    Simultanagnosia, in which subjects report a piecemeal visual experience, offers an important probe of human attention. We studied 2 subjects with simultanagnosia following bilateral superior occipital strokes. Compared with controls, they could orient attention to spatial targets in visual, auditory, and mixed-modal conditions. A different task required immediate response to the appearance or disappearance at unpredictable intervals of any element in a random-dot CRT display. The subject tested could detect less than 50% of 1,600 events, and had increased "mirages" and prolonged reaction times. Undetected events occurred anywhere and formed temporal clusters. Application of signal-detection theory confirmed abnormal sensitivity and response bias (d' and beta). Yet performance improved when a valid cue introduced events in the random display. Our results suggest that simultanagnosia was related to an inability to sustain visuospatial attention across an array, corresponding to processing failure at a level of long-range (global) spatiotemporal interactions among converging inputs from early vision. The operations for orienting and sustaining attention may be dissociable at visual association cortex levels.

  16. Dot-probe evaluation of selective attentional processing of pain cues in patients with chronic headaches.

    Science.gov (United States)

    Asmundson, Gordon J G; Carleton, R Nicholas; Ekong, Jane

    2005-03-01

    Evidence supporting the notion that patients with chronic pain are characterized by attentional biases for sensory and affect pain words, and that such biases are mediated by fear of pain, is mixed. The present investigation was an attempt to replicate and extend initial findings obtained with the dot-probe task. Thirty patients with chronic headache and 19 healthy controls were tested using a dot-probe task including affect pain, sensory pain, and neutral words. Individual difference variables, including fear of pain measures, were assessed and considered in analyses. Selective attention was denoted using the bias index, congruency index, and incongruency index. There were no significant between-group differences or interactions between group and word type observed for any of the indices of selective attention. Across groups there was evidence for a significant association between anxiety sensitivity and the bias index for sensory pain words, and between affective description of current pain and the incongruency index for affect pain words. These results do not provide convincing evidence that patients with chronic headache selectively attend to affect or sensory pain cues when compared to healthy controls. The significant cross-groups associations between anxiety sensitivity and current pain description and indices of selective attention are consistent with the notion that attentional biases may be influenced by fear propensity and current concerns. Implications of the findings and future research directions are discussed.

  17. Is action video gaming related to sustained attention of adolescents?

    Science.gov (United States)

    Trisolini, Daniela Carmen; Petilli, Marco Alessandro; Daini, Roberta

    2017-03-24

    Over the past few years, an increasing number of studies have shown that playing action video games can have positive effects on tasks that involve attention and visual-spatial cognition (e.g. visual search, enumeration tasks, tracking multiple objects). Although playing action video games can improve several cognitive functions, the intensive interaction with the exciting, challenging, intrinsically-stimulating and perceptually-appealing game environments may adversely affect other functions, including the ability to maintain attention when the level of stimulation is not as intense. This study investigated whether a relationship existed between action video gaming and sustained attention performance in a sample of 45 Italian teenagers. After completing a questionnaire about their video-games habits, participants were divided into Action Video Game Player and Non Action Video Game Player groups and underwent cognitive tests. The results confirm previous findings of studies of Action Video Game Players, as they had significantly enhanced performance for instantly enumerating a set of items. Nevertheless, we found that the drop in performance over time, typical of a sustained attention task, was significantly greater in the Action Video Game Player compared with the Non Action Video Game Player group. This result is consistent with our hypothesis and demonstrates a negative effect of playing action video games.

  18. Boredom, sustained attention and the default mode network.

    Science.gov (United States)

    Danckert, James; Merrifield, Colleen

    2016-03-15

    Boredom is a ubiquitous human experience that can best be described as an inability to engage with one's environment despite the motivation to do so. Boredom is perceived as a negative experience and demonstrates strong associations with other negatively valenced states including depression and aggression. Although boredom has been shown to be elevated in neurological and psychiatric illnesses, little is known about the neural underpinnings of the state. We scanned the brains of healthy participants under four separate conditions: a resting state scan, a sustained attention task and two video-based mood inductions, one known to produce boredom and another we validated to produce a state of interest or engagement. Using independent components analyses, results showed common regions of correlated activation in posterior regions of the so-called default mode network (DMN) of the brain across all four conditions. The sustained attention and boredom induction scans were differentiated from the resting state scan by the presence of anticorrelated activity-i.e. when DMN regions were active, this region was deactivated-in the anterior insula cortex. This same region demonstrated correlated activity with both the DMN and the regions associated with attentional control during the interest mood induction. We interpret these findings to suggest that boredom represents a failure to engage executive control networks when faced with a monotonous task-in other words, when the task demands some level of engagement (watch the movie, search for infrequent targets), but is so mundane that attempts to do so fail.

  19. Psychometric properties of Persian version of the Sustained Auditory Attention Capacity Test in children with attention deficit-hyperactivity disorder.

    Science.gov (United States)

    Soltanparast, Sanaz; Jafari, Zahra; Sameni, Seyed Jalal; Salehi, Masoud

    2014-01-01

    The purpose of the present study was to evaluate the psychometric properties (validity and reliability) of the Persian version of the Sustained Auditory Attention Capacity Test in children with attention deficit hyperactivity disorder. The Persian version of the Sustained Auditory Attention Capacity Test was constructed to assess sustained auditory attention using the method provided by Feniman and colleagues (2007). In this test, comments were provided to assess the child's attentional deficit by determining inattention and impulsiveness error, the total scores of the sustained auditory attention capacity test and attention span reduction index. In the present study for determining the validity and reliability of in both Rey Auditory Verbal Learning test and the Persian version of the Sustained Auditory Attention Capacity Test (SAACT), 46 normal children and 41 children with Attention Deficit Hyperactivity (ADHD), all right-handed and aged between 7 and 11 of both genders, were evaluated. In determining convergent validity, a negative significant correlation was found between the three parts of the Rey Auditory Verbal Learning test (first, fifth, and immediate recall) and all indicators of the SAACT except attention span reduction. By comparing the test scores between the normal and ADHD groups, discriminant validity analysis showed significant differences in all indicators of the test except for attention span reduction (pCapacity test has good validity and reliability, that matches other reliable tests, and it can be used for the identification of children with attention deficits and if they suspected to have Attention Deficit Hyperactivity Disorder.

  20. Beyond time and space: The effect of a lateralized sustained attention task and brain stimulation on spatial and selective attention.

    Science.gov (United States)

    Shalev, Nir; De Wandel, Linde; Dockree, Paul; Demeyere, Nele; Chechlacz, Magdalena

    2017-10-03

    The Theory of Visual Attention (TVA) provides a mathematical formalisation of the "biased competition" account of visual attention. Applying this model to individual performance in a free recall task allows the estimation of 5 independent attentional parameters: visual short-term memory (VSTM) capacity, speed of information processing, perceptual threshold of visual detection; attentional weights representing spatial distribution of attention (spatial bias), and the top-down selectivity index. While the TVA focuses on selection in space, complementary accounts of attention describe how attention is maintained over time, and how temporal processes interact with selection. A growing body of evidence indicates that different facets of attention interact and share common neural substrates. The aim of the current study was to modulate a spatial attentional bias via transfer effects, based on a mechanistic understanding of the interplay between spatial, selective and temporal aspects of attention. Specifically, we examined here: (i) whether a single administration of a lateralized sustained attention task could prime spatial orienting and lead to transferable changes in attentional weights (assigned to the left vs right hemi-field) and/or other attentional parameters assessed within the framework of TVA (Experiment 1); (ii) whether the effects of such spatial-priming on TVA parameters could be further enhanced by bi-parietal high frequency transcranial random noise stimulation (tRNS) (Experiment 2). Our results demonstrate that spatial attentional bias, as assessed within the TVA framework, was primed by sustaining attention towards the right hemi-field, but this spatial-priming effect did not occur when sustaining attention towards the left. Furthermore, we show that bi-parietal high-frequency tRNS combined with the rightward spatial-priming resulted in an increased attentional selectivity. To conclude, we present a novel, theory-driven method for attentional modulation

  1. The Role of Sustained Attention in the Production of Conjoined Noun Phrases: An Individual Differences Study

    Science.gov (United States)

    Jongman, Suzanne R.; Meyer, Antje S.; Roelofs, Ardi

    2015-01-01

    It has previously been shown that language production, performed simultaneously with a nonlinguistic task, involves sustained attention. Sustained attention concerns the ability to maintain alertness over time. Here, we aimed to replicate the previous finding by showing that individuals call upon sustained attention when they plan single noun phrases (e.g., "the carrot") and perform a manual arrow categorization task. In addition, we investigated whether speakers also recruit sustained attention when they produce conjoined noun phrases (e.g., "the carrot and the bucket") describing two pictures, that is, when both the first and second task are linguistic. We found that sustained attention correlated with the proportion of abnormally slow phrase-production responses. Individuals with poor sustained attention displayed a greater number of very slow responses than individuals with better sustained attention. Importantly, this relationship was obtained both for the production of single phrases while performing a nonlinguistic manual task, and the production of noun phrase conjunctions in referring to two spatially separated objects. Inhibition and updating abilities were also measured. These scores did not correlate with our measure of sustained attention, suggesting that sustained attention and executive control are distinct. Overall, the results suggest that planning conjoined noun phrases involves sustained attention, and that language production happens less automatically than has often been assumed. PMID:26335441

  2. Gender Differences in Sustained Attentional Control Relate to Gender Inequality across Countries.

    Science.gov (United States)

    Riley, Elizabeth; Okabe, Hidefusa; Germine, Laura; Wilmer, Jeremy; Esterman, Michael; DeGutis, Joseph

    2016-01-01

    Sustained attentional control is critical for everyday tasks and success in school and employment. Understanding gender differences in sustained attentional control, and their potential sources, is an important goal of psychology and neuroscience and of great relevance to society. We used a large web-based sample (n = 21,484, from testmybrain.org) to examine gender differences in sustained attentional control. Our sample included participants from 41 countries, allowing us to examine how gender differences in each country relate to national indices of gender equality. We found significant gender differences in certain aspects of sustained attentional control. Using indices of gender equality, we found that overall sustained attentional control performance was lower in countries with less equality and that there were greater gender differences in performance in countries with less equality. These findings suggest that creating sociocultural conditions which value women and men equally can improve a component of sustained attention and reduce gender disparities in cognition.

  3. Endogenously- and Exogenously-Driven Selective Sustained Attention: Contributions to Learning in Kindergarten Children

    Science.gov (United States)

    Erickson, Lucy C.; Thiessen, Erik D.; Godwin, Karrie E.; Dickerson, John P.; Fisher, Anna V.

    2015-01-01

    Selective sustained attention is vital for higher order cognition. Although endogenous and exogenous factors influence selective sustained attention, assessment of the degree to which these factors influence performance and learning is often challenging. We report findings from the Track-It task, a paradigm that aims to assess the contribution of…

  4. The Role of Sustained Attention in the Production of Conjoined Noun Phrases: An Individual Differences Study

    NARCIS (Netherlands)

    Jongman, S.R.; Meyer, A.S.; Roelofs, A.P.A.

    2015-01-01

    It has previously been shown that language production, performed simultaneously with a nonlinguistic task, involves sustained attention. Sustained attention concerns the ability to maintain alertness over time. Here, we aimed to replicate the previous finding by showing that individuals call upon

  5. rTMS over bilateral inferior parietal cortex induces decrement of spatial sustained attention

    Directory of Open Access Journals (Sweden)

    Jeyeon eLee

    2013-02-01

    Full Text Available Sustained attention is an essential brain function that enables a subject to maintain attention level over the time of a task. In previous work, the right inferior parietal lobe (IPL has been reported as one of the main brain regions related to sustained attention, however, the right lateralization of vigilance/sustained attention is unclear because information about the network for sustained attention is traditionally provided by neglect patients who typically have right brain damage. Here, we investigated sustained attention by applying a virtual lesion technique, transcranial magnetic stimulation (TMS, over the left and right superior parietal lobe (SPL and IPL. We used two different types of visual sustained attention tasks: spatial (location based and non-spatial (feature based. When the participants performed the spatial task, repetitive TMS (rTMS over either the right or left IPL induced a significant decrement of sustained attention causing a progressive increment of errors and response time. In contrast, participants’ performance was not changed by rTMS on the non-spatial task. Also, omission errors (true negative gradually increased with time on right and left IPL rTMS conditions, while commission errors (false positive were relatively stable. These findings suggest that the maintenance of attention, especially in tasks regarding spatial location, is not uniquely lateralized to the right IPL, but may also involve participation of the left IPL as well.

  6. Picture naming in typically developing and language-impaired children: the role of sustained attention.

    Science.gov (United States)

    Jongman, Suzanne R; Roelofs, Ardi; Scheper, Annette R; Meyer, Antje S

    2017-05-01

    Children with specific language impairment (SLI) have problems not only with language performance but also with sustained attention, which is the ability to maintain alertness over an extended period of time. Although there is consensus that this ability is impaired with respect to processing stimuli in the auditory perceptual modality, conflicting evidence exists concerning the visual modality. To address the outstanding issue whether the impairment in sustained attention is limited to the auditory domain, or if it is domain-general. Furthermore, to test whether children's sustained attention ability relates to their word-production skills. Groups of 7-9 year olds with SLI (N = 28) and typically developing (TD) children (N = 22) performed a picture-naming task and two sustained attention tasks, namely auditory and visual continuous performance tasks (CPTs). Children with SLI performed worse than TD children on picture naming and on both the auditory and visual CPTs. Moreover, performance on both the CPTs correlated with picture-naming latencies across developmental groups. These results provide evidence for a deficit in both auditory and visual sustained attention in children with SLI. Moreover, the study indicates there is a relationship between domain-general sustained attention and picture-naming performance in both TD and language-impaired children. Future studies should establish whether this relationship is causal. If attention influences language, training of sustained attention may improve language production in children from both developmental groups. © 2016 Royal College of Speech and Language Therapists.

  7. Selective and sustained attention in children with spina bifida myelomeningocele

    DEFF Research Database (Denmark)

    Caspersen, Ida Dyhr; Habekost, Thomas

    2013-01-01

    Spina bifida myelomeningocele (SBM) is a neural tube defect that has been related to deficits in several cognitive domains including attention. Attention function in children with SBM has often been studied using tasks that are confounded by complex motor demands or tasks that do not clearly...

  8. Use of a sustained visual attention task to determine children at risk for learning problems.

    Science.gov (United States)

    Richman, J E

    1986-01-01

    Use of a sustained visual attention task to determine children "at risk" for learning problems. The purpose in the study was to compare the sustained visual attention performance of 42 first grade children on a 9.5 minute continuous performance test, as measured by error rate and off-task visual behaviors, e.g., off-task looking time and number of fixations off the task, with a measure of impulsivity and a teacher rating scale of classroom behavior designed to identify children with potential learning disabilities. The present findings suggest that the measurement of "off-task looking time" and "off-task fixations" during a sustained visual attention test are significantly related to the classroom teacher's observation of personal-social behavior and the child's decision making style. This approach for measuring sustained attention has potential use as a clinical tool in identifying and monitoring treatment methodologies for children considered "at risk" for attention and learning problems.

  9. A Persian version of the sustained auditory attention capacity test and its results in normal children

    Directory of Open Access Journals (Sweden)

    Sanaz Soltanparast

    2013-03-01

    Full Text Available Background and Aim: Sustained attention refers to the ability to maintain attention in target stimuli over a sustained period of time. This study was conducted to develop a Persian version of the sustained auditory attention capacity test and to study its results in normal children.Methods: To develop the Persian version of the sustained auditory attention capacity test, like the original version, speech stimuli were used. The speech stimuli consisted of one hundred monosyllabic words consisting of a 20 times random of and repetition of the words of a 21-word list of monosyllabic words, which were randomly grouped together. The test was carried out at comfortable hearing level using binaural, and diotic presentation modes on 46 normal children of 7 to 11 years of age of both gender.Results: There was a significant difference between age, and an average of impulsiveness error score (p=0.004 and total score of sustained auditory attention capacity test (p=0.005. No significant difference was revealed between age, and an average of inattention error score and attention reduction span index. Gender did not have a significant impact on various indicators of the test.Conclusion: The results of this test on a group of normal hearing children confirmed its ability to measure sustained auditory attention capacity through speech stimuli.

  10. Heart rate variability and sustained attention in ADHD children

    NARCIS (Netherlands)

    Börger, N.A.; Van der Meere, J.J.; Ronner, A.; Alberts, E.; Geuze, R.H.; Bogte, H

    The major goal of the current study was to investigate the association between continuous performance tests (CPTs) and the heart rate variability (HRV) of attention deficit hyperactivity disorder (ADHD) children. The HRV, specifically the 0.10-Hz component, may be considered to be a

  11. The effect of mental fatigue on sustained attention: an fNIRS study

    Science.gov (United States)

    Zhang, Zhen; Yang, Hanjun; Cao, Yong; Xu, Fenggang; Jiang, Jin; Jiao, Xuejun

    2017-01-01

    Sustained attention is the ability to keep focused and vigilance for long time in external stimulation, which was crucial in safe-critical human-machine system. While the ability of sustained attention will decline because of mental fatigue, even lead to serious accidents in fatigue state. Therefore, it is of great significance to explore the impact of fatigue on sustained attention. Functional Near-Infrared Spectroscopy (fNIRS) can measure cerebral hemoglobin in order to reflect cognitive function indirectly. In previous related fatigue studies, monotonous and long-time CPT (continuous performance test task) was often used to explore the performance change and brain activity, but the effect of time on task (TOT) was always involved. In this study, in order to avoid the TOT effect, the sustained attention task and fatigue task were separated. It was adopted in the study that the modified continuous performance test (CPT) was chosen as the sustained attention task and verbal 2-back task as the fatigue induced task. The fNIRS signals were extracted from 10 channels in the prefrontal cortex (PFC) from 20 healthy subjects. Studies found that cerebral lateralization increased significantly from alert to fatigue state in sustained attention task. Besides, Average oxyhemoglobin (HBO) of PFC increased significantly from alert to fatigue task, and the spatial pattern of activity of oxyhemoglobin also changed, which c be sensitive features to fatigue detection.

  12. Incidental Learning, Distraction, and Sustained Attention in Hyperactive and Control Subjects.

    Science.gov (United States)

    Aman, Michael G.; Turbott, Sarah H.

    1986-01-01

    Thirty-two hyperactive children (ages 5-11) and 32 controls were tested on (1) a component selection task, measuring serial memory and incidental learning and (2) a cancellation task, assessing attentional variables and distractibility. It was concluded that a deficit in sustained attention and impulsivity best described the group differences.…

  13. A resource-control account of sustained attention: evidence from mind-wandering and vigilance paradigms.

    Science.gov (United States)

    Thomson, David R; Besner, Derek; Smilek, Daniel

    2015-01-01

    Staying attentive is challenging enough when carrying out everyday tasks, such as reading or sitting through a lecture, and failures to do so can be frustrating and inconvenient. However, such lapses may even be life threatening, for example, if a pilot fails to monitor an oil-pressure gauge or if a long-haul truck driver fails to notice a car in his or her blind spot. Here, we explore two explanations of sustained-attention lapses. By one account, task monotony leads to an increasing preoccupation with internal thought (i.e., mind wandering). By another, task demands result in the depletion of information-processing resources that are needed to perform the task. A review of the sustained-attention literature suggests that neither theory, on its own, adequately explains the full range of findings. We propose a novel framework to explain why attention lapses as a function of time-on-task by combining aspects of two different theories of mind wandering: attentional resource (Smallwood & Schooler, 2006) and control failure (McVay & Kane, 2010). We then use our "resource-control" theory to explain performance decrements in sustained-attention tasks. We end by making some explicit predictions regarding mind wandering in general and sustained-attention performance in particular. © The Author(s) 2014.

  14. Associations Among Family Environment, Sustained Attention, and School Readiness for Low-Income Children

    Science.gov (United States)

    Razza, Rachel A.; Martin, Anne; Brooks-Gunn, Jeanne

    2011-01-01

    In this study, we examined the developmental pathways from children’s family environment to school readiness within a low-income sample (N = 1,046), with a specific focus on the role of sustained attention. Six distinct factors of the family environment representing maternal parenting behaviors, the physical home environment, and maternal mental health at 3 years of age were explored as independent predictors of children’s observed sustained attention as well as cognitive and behavioral outcomes at 5 years of age. Children were grouped by poverty status (poor vs. near-poor). Results suggest specificity in the associations among attention (focused attention and lack of impulsivity) and its correlates, with different patterns emerging by poverty status group. Overall, the family environment was largely unrelated to children’s sustained attention. For both groups, focused attention was associated with receptive vocabulary; however, it partially mediated the association between maternal lack of hostility and receptive vocabulary only among the near-poor. In addition, lack of impulsivity was associated with both receptive vocabulary and externalizing behaviors but only for the poor group. Findings indicate sustained attention as a potential target for efforts aimed at enhancing school readiness among predominantly poor children. PMID:20677860

  15. Reaction Times to Consecutive Automation Failures: A Function of Working Memory and Sustained Attention.

    Science.gov (United States)

    Jipp, Meike

    2016-12-01

    This study explored whether working memory and sustained attention influence cognitive lock-up, which is a delay in the response to consecutive automation failures. Previous research has demonstrated that the information that automation provides about failures and the time pressure that is associated with a task influence cognitive lock-up. Previous research has also demonstrated considerable variability in cognitive lock-up between participants. This is why individual differences might influence cognitive lock-up. The present study tested whether working memory-including flexibility in executive functioning-and sustained attention might be crucial in this regard. Eighty-five participants were asked to monitor automated aircraft functions. The experimental manipulation consisted of whether or not an initial automation failure was followed by a consecutive failure. Reaction times to the failures were recorded. Participants' working-memory and sustained-attention abilities were assessed with standardized tests. As expected, participants' reactions to consecutive failures were slower than their reactions to initial failures. In addition, working-memory and sustained-attention abilities enhanced the speed with which participants reacted to failures, more so with regard to consecutive than to initial failures. The findings highlight that operators with better working memory and sustained attention have small advantages when initial failures occur, but their advantages increase across consecutive failures. The results stress the need to consider personnel selection strategies to mitigate cognitive lock-up in general and training procedures to enhance the performance of low ability operators. © 2016, Human Factors and Ergonomics Society.

  16. Training for Vigilance on the Move: A Video Game-Based Paradigm for Sustained Attention.

    Science.gov (United States)

    Szalma, J L; Daly, T N; Teo, G W L; Hancock, G M; Hancock, P A

    2017-11-10

    The capacity for superior vigilance can be trained by using knowledge of results (KR). Ourpresent experiments demonstrate the efficacy of such training using a first-person perspective movement videogame-based platform in samples ofstudents and Soldiers.Effectiveness was assessedby manipulating KR during a training phase and withdrawing it in a subsequent transfer phase. Relative to a no KR control condition, KR systematically improved performance for both Soldiers and students. These results build upon our previous findings that demonstrated that a video game-based platform can be used to create a movement-centered sustained attention task with important elements of traditional vigilance. The results indicate that KR effects in sustained attention extend to a first person perspective movement based paradigm, and that these effects occur in professional military as well as a more general population.Such sustained attention training can save lives and the present findings demonstrate one particular avenue to achieve this goal. Practitioner Summary Sustained attention can be trained by means of knowledge of results using a videogame-based platform with samples of students and Soldiers.Four experiments demonstrate that a dynamic, first-person perspective video game environment can serve to support effective sustained attention training in professional military as well as a more general population.

  17. The relationship between sustained attention and aerobic fitness in a group of young adults

    Directory of Open Access Journals (Sweden)

    Luis F. Ciria

    2017-09-01

    Full Text Available Background A growing set of studies has shown a positive relationship between aerobic fitness and a broad array of cognitive functions. However, few studies have focused on sustained attention, which has been considered a fundamental cognitive process that underlies most everyday activities. The purpose of this study was to investigate the role of aerobic fitness as a key factor in sustained attention capacities in young adults. Methods Forty-four young adults (18–23 years were divided into two groups as a function of the level of aerobic fitness (high-fit and low-fit. Participants completed the Psychomotor Vigilance Task (PVT and an oddball task where they had to detect infrequent targets presented among frequent non-targets. Results The analysis of variance (ANOVA showed faster responses for the high-fit group than for the low-fit group in the PVT, replicating previous accounts. In the oddball task, the high-fit group maintained their accuracy (ACC rate of target detection over time, while the low-fit group suffered a significant decline of response ACC throughout the task. Discussion Importantly, the results show that the greater sustained attention capacity of high-fit young adults is not specific to a reaction time (RT sustained attention task like the PVT, but it is also evident in an ACC oddball task. In sum, the present findings point to the important role of aerobic fitness on sustained attention capacities in young adults.

  18. Sustained attention performance during sleep deprivation associates with instability in behavior and physiologic measures at baseline.

    Science.gov (United States)

    Chua, Eric Chern-Pin; Yeo, Sing-Chen; Lee, Ivan Tian-Guang; Tan, Luuan-Chin; Lau, Pauline; Cai, Shiwei; Zhang, Xiaodong; Puvanendran, Kathiravelu; Gooley, Joshua J

    2014-01-01

    To identify baseline behavioral and physiologic markers that associate with individual differences in sustained attention during sleep deprivation. In a retrospective study, ocular, electrocardiogram, and electroencephalogram (EEG) measures were compared in subjects who were characterized as resilient (n = 15) or vulnerable (n = 15) to the effects of total sleep deprivation on sustained attention. Chronobiology and Sleep Laboratory, Duke-NUS Graduate Medical School Singapore. Healthy volunteers aged 22-32 years from the general population. Subjects were kept awake for at least 26 hours under constant environmental conditions. Every 2 hours, sustained attention was assessed using a 10-minute psychomotor vigilance task (PVT). During baseline sleep and recovery sleep, EEG slow wave activity was similar in resilient versus vulnerable subjects, suggesting that individual differences in vulnerability to sleep loss were not related to differences in homeostatic sleep regulation. Rather, irrespective of time elapsed since wake, subjects who were vulnerable to sleep deprivation exhibited slower and more variable PVT response times, lower and more variable heart rate, and higher and more variable EEG spectral power in the theta frequency band (6.0-7.5 Hz). Performance decrements in sustained attention during sleep deprivation associate with instability in behavioral and physiologic measures at baseline. Small individual differences in sustained attention that are present at baseline are amplified during prolonged wakefulness, thus contributing to large between-subjects differences in performance and sleepiness.

  19. Language Proficiency and Sustained Attention in Monolingual and Bilingual Children with and without Language Impairment

    Directory of Open Access Journals (Sweden)

    Tessel Boerma

    2017-07-01

    Full Text Available Background: The language profiles of children with language impairment (LI and bilingual children can show partial, and possibly temporary, overlap. The current study examined the persistence of this overlap over time. Furthermore, we aimed to better understand why the language profiles of these two groups show resemblance, testing the hypothesis that the language difficulties of children with LI reflect a weakened ability to maintain attention to the stream of linguistic information. Consequent incomplete processing of language input may lead to delays that are similar to those originating from reductions in input frequency.Methods: Monolingual and bilingual children with and without LI (N = 128, aged 5–8 years old, participated in this study. Dutch receptive vocabulary and grammatical morphology were assessed at three waves. In addition, auditory and visual sustained attention were tested at wave 1. Mediation analyses were performed to examine relationships between LI, sustained attention, and language skills.Results: Children with LI and bilingual children were outperformed by their typically developing (TD and monolingual peers, respectively, on vocabulary and morphology at all three waves. The vocabulary difference between monolinguals and bilinguals decreased over time. In addition, children with LI had weaker auditory and visual sustained attention skills relative to TD children, while no differences between monolinguals and bilinguals emerged. Auditory sustained attention mediated the effect of LI on vocabulary and morphology in both the monolingual and bilingual groups of children. Visual sustained attention only acted as a mediator in the bilingual group.Conclusion: The findings from the present study indicate that the overlap between the language profiles of children with LI and bilingual children is particularly large for vocabulary in early (preschool years and reduces over time. Results furthermore suggest that the overlap may be

  20. Interpersonal early-life trauma alters amygdala connectivity and sustained attention performance.

    Science.gov (United States)

    Fortenbaugh, Francesca C; Corbo, Vincent; Poole, Victoria; McGlinchey, Regina; Milberg, William; Salat, David; DeGutis, Joseph; Esterman, Michael

    2017-05-01

    Interpersonal early life trauma (I-ELT) is associated with a myriad of functional impairments in adulthood, increased risk of drug addiction, and neuropsychiatric disorders. While deficits in emotional regulation and amygdala functioning are well characterized, deficits in general cognitive functioning have also been documented. However, the neural underpinnings of cognitive dysfunction in adults with a history of I-ELT and the potential relationship between amygdala-based functional connectivity and behavioral performance are currently poorly understood. This study examined how I-ELT affects the cognitive and neural mechanisms supporting sustained attention. A total of 66 Veterans (18 with and 48 without a history of I-ELT) completed a nonemotional sustained attention task during functional MRI. The individuals with I-ELT showed significant impairments in sustained attention (i.e., higher error rates, greater response variability). This cohort exhibited increased amygdala functional connectivity with the prefrontal cortex and decreased functional connectivity with the parahippocampal gyrus when compared to those without I-ELT. These connections were significantly correlated with individual differences in sustained attention performance. Notably, classification analyses revealed that the pattern of amygdala connectivity across the whole brain was able to classify I-ELT status with 70% accuracy. These results provide evidence of a lasting negative impact for those with a history of I-ELT on sustained attention ability. They also highlight a critical role for amygdala functioning in cognitive control and sustained attention for those with a history of I-ELT, which may underlie the observed attention deficits in clinical assessments and cognitive tests involving both emotional and nonemotional stimuli.

  1. Language Proficiency and Sustained Attention in Monolingual and Bilingual Children with and without Language Impairment

    Science.gov (United States)

    Boerma, Tessel; Leseman, Paul; Wijnen, Frank; Blom, Elma

    2017-01-01

    Background: The language profiles of children with language impairment (LI) and bilingual children can show partial, and possibly temporary, overlap. The current study examined the persistence of this overlap over time. Furthermore, we aimed to better understand why the language profiles of these two groups show resemblance, testing the hypothesis that the language difficulties of children with LI reflect a weakened ability to maintain attention to the stream of linguistic information. Consequent incomplete processing of language input may lead to delays that are similar to those originating from reductions in input frequency. Methods: Monolingual and bilingual children with and without LI (N = 128), aged 5–8 years old, participated in this study. Dutch receptive vocabulary and grammatical morphology were assessed at three waves. In addition, auditory and visual sustained attention were tested at wave 1. Mediation analyses were performed to examine relationships between LI, sustained attention, and language skills. Results: Children with LI and bilingual children were outperformed by their typically developing (TD) and monolingual peers, respectively, on vocabulary and morphology at all three waves. The vocabulary difference between monolinguals and bilinguals decreased over time. In addition, children with LI had weaker auditory and visual sustained attention skills relative to TD children, while no differences between monolinguals and bilinguals emerged. Auditory sustained attention mediated the effect of LI on vocabulary and morphology in both the monolingual and bilingual groups of children. Visual sustained attention only acted as a mediator in the bilingual group. Conclusion: The findings from the present study indicate that the overlap between the language profiles of children with LI and bilingual children is particularly large for vocabulary in early (pre)school years and reduces over time. Results furthermore suggest that the overlap may be explained by

  2. Falls and falls efficacy: the role of sustained attention in older adults

    Directory of Open Access Journals (Sweden)

    O'Halloran Aisling M

    2011-12-01

    Full Text Available Abstract Background Previous evidence indicates that older people allocate more of their attentional resources toward their gait and that the attention-related changes that occur during aging increase the risk of falls. The aim of this study was to investigate whether performance and variability in sustained attention is associated with falls and falls efficacy in older adults. Methods 458 community-dwelling adults aged ≥ 60 years underwent a comprehensive geriatric assessment. Mean and variability of reaction time (RT, commission errors and omission errors were recorded during a fixed version of the Sustained Attention to Response Task (SART. RT variability was decomposed using the Fast Fourier Transform (FFT procedure, to help characterise variability associated with the arousal and vigilance aspects of sustained attention. The number of self-reported falls in the previous twelve months, and falls efficacy (Modified Falls Efficacy Scale were also recorded. Results Significant increases in the mean and variability of reaction time on the SART were significantly associated with both falls (p Conclusions Greater variability in sustained attention is strongly correlated with retrospective falls and to a lesser degree with reduced falls efficacy. This cognitive measure may provide a novel and valuable biomarker for falls in older adults, potentially allowing for early detection and the implementation of preventative intervention strategies.

  3. Retro-cue benefits in working memory without sustained focal attention.

    Science.gov (United States)

    Rerko, Laura; Souza, Alessandra S; Oberauer, Klaus

    2014-07-01

    In working memory (WM) tasks, performance can be boosted by directing attention to one memory object: When a retro-cue in the retention interval indicates which object will be tested, responding is faster and more accurate (the retro-cue benefit). We tested whether the retro-cue benefit in WM depends on sustained attention to the cued object by inserting an attention-demanding interruption task between the retro-cue and the memory test. In the first experiment, the interruption task required participants to shift their visual attention away from the cued representation and to a visual classification task on colors. In the second and third experiments, the interruption task required participants to shift their focal attention within WM: Attention was directed away from the cued representation by probing another representation from the memory array prior to probing the cued object. The retro-cue benefit was not attenuated by shifts of perceptual attention or by shifts of attention within WM. We concluded that sustained attention is not needed to maintain the cued representation in a state of heightened accessibility.

  4. ERP Indications for Sustained and Transient Auditory Spatial Attention with Different Lateralization Cues

    Science.gov (United States)

    Widmann, Andreas; Schröger, Erich

    The presented study was designed to investigate ERP effects of auditory spatial attention in sustained attention condition (where the to-be-attended location is defined in a blockwise manner) and in a transient attention condition (where the to-be-attended location is defined in a trial-by-trial manner). Lateralization in the azimuth plane was manipulated (a) via monaural presentation of l- and right-ear sounds, (b) via interaural intensity differences, (c) via interaural time differences, (d) via an artificial-head recording, and (e) via free-field stimulation. Ten participants were delivered with frequent Nogo- and infrequent Go-Stimuli. In one half of the experiment participants were instructed to press a button if they detected a Go-stimulus at a predefined side (sustained attention), in the other half they were required to detect Go-stimuli following an arrow-cue at the cued side (transient attention). Results revealed negative differences (Nd) between ERPs elicited by to-be-attended and to-be-ignored sounds in all conditions. These Nd-effects were larger for the sustained than for the transient attention condition indicating that attentional selection according to spatial criteria is improved when subjects can focus to one and the same location for a series of stimuli.

  5. Falls and falls efficacy: the role of sustained attention in older adults.

    Science.gov (United States)

    O'Halloran, Aisling M; Pénard, Nils; Galli, Alessandra; Fan, Chie Wei; Robertson, Ian H; Kenny, Rose Anne

    2011-12-19

    Previous evidence indicates that older people allocate more of their attentional resources toward their gait and that the attention-related changes that occur during aging increase the risk of falls. The aim of this study was to investigate whether performance and variability in sustained attention is associated with falls and falls efficacy in older adults. 458 community-dwelling adults aged ≥ 60 years underwent a comprehensive geriatric assessment. Mean and variability of reaction time (RT), commission errors and omission errors were recorded during a fixed version of the Sustained Attention to Response Task (SART). RT variability was decomposed using the Fast Fourier Transform (FFT) procedure, to help characterise variability associated with the arousal and vigilance aspects of sustained attention.The number of self-reported falls in the previous twelve months, and falls efficacy (Modified Falls Efficacy Scale) were also recorded. Significant increases in the mean and variability of reaction time on the SART were significantly associated with both falls (p older adults. An increase in omission errors was also associated with falls (p attention was a retrospective predictor of falling (p attention is strongly correlated with retrospective falls and to a lesser degree with reduced falls efficacy. This cognitive measure may provide a novel and valuable biomarker for falls in older adults, potentially allowing for early detection and the implementation of preventative intervention strategies.

  6. Examining the Relative Contribution of Memory Updating, Attention Focus Switching, and Sustained Attention to Children’s Verbal Working Memory Span

    OpenAIRE

    Magimairaj, Beula M.; Montgomery, James W.

    2013-01-01

    Whereas considerable developmental memory research has examined the contributions of short-term memory, processing efficiency, retention duration, and scope of attention to complex memory span, little is known about the influence of controlled attention. The present study investigated the relative influence of three understudied attention mechanisms on the verbal working memory span of school-age children: memory updating; attention focus switching; and sustained attention. Results of general...

  7. Sustained Attention Performance during Sleep Deprivation Associates with Instability in Behavior and Physiologic Measures at Baseline

    Science.gov (United States)

    Chua, Eric Chern-Pin; Yeo, Sing-Chen; Lee, Ivan Tian-Guang; Tan, Luuan-Chin; Lau, Pauline; Cai, Shiwei; Zhang, Xiaodong; Puvanendran, Kathiravelu; Gooley, Joshua J.

    2014-01-01

    Study Objectives: To identify baseline behavioral and physiologic markers that associate with individual differences in sustained attention during sleep deprivation. Design: In a retrospective study, ocular, electrocardiogram, and electroencephalogram (EEG) measures were compared in subjects who were characterized as resilient (n = 15) or vulnerable (n = 15) to the effects of total sleep deprivation on sustained attention. Setting: Chronobiology and Sleep Laboratory, Duke-NUS Graduate Medical School Singapore. Participants: Healthy volunteers aged 22-32 years from the general population. Interventions: Subjects were kept awake for at least 26 hours under constant environmental conditions. Every 2 hours, sustained attention was assessed using a 10-minute psychomotor vigilance task (PVT). Measurements and Results: During baseline sleep and recovery sleep, EEG slow wave activity was similar in resilient versus vulnerable subjects, suggesting that individual differences in vulnerability to sleep loss were not related to differences in homeostatic sleep regulation. Rather, irrespective of time elapsed since wake, subjects who were vulnerable to sleep deprivation exhibited slower and more variable PVT response times, lower and more variable heart rate, and higher and more variable EEG spectral power in the theta frequency band (6.0-7.5 Hz). Conclusions: Performance decrements in sustained attention during sleep deprivation associate with instability in behavioral and physiologic measures at baseline. Small individual differences in sustained attention that are present at baseline are amplified during prolonged wakefulness, thus contributing to large between-subjects differences in performance and sleepiness. Citation: Chua EC; Yeo SC; Lee IT; Tan LC; Lau P; Cai S; Zhang X; Puvanendran K; Gooley JJ. Sustained attention performance during sleep deprivation associates with instability in behavior and physiologic measures at baseline. SLEEP 2014;37(1):27-39. PMID:24470693

  8. Falls and falls efficacy: the role of sustained attention in older adults

    LENUS (Irish Health Repository)

    O'Halloran, Aisling M

    2011-12-19

    Abstract Background Previous evidence indicates that older people allocate more of their attentional resources toward their gait and that the attention-related changes that occur during aging increase the risk of falls. The aim of this study was to investigate whether performance and variability in sustained attention is associated with falls and falls efficacy in older adults. Methods 458 community-dwelling adults aged ≥ 60 years underwent a comprehensive geriatric assessment. Mean and variability of reaction time (RT), commission errors and omission errors were recorded during a fixed version of the Sustained Attention to Response Task (SART). RT variability was decomposed using the Fast Fourier Transform (FFT) procedure, to help characterise variability associated with the arousal and vigilance aspects of sustained attention. The number of self-reported falls in the previous twelve months, and falls efficacy (Modified Falls Efficacy Scale) were also recorded. Results Significant increases in the mean and variability of reaction time on the SART were significantly associated with both falls (p < 0.01) and reduced falls efficacy (p < 0.05) in older adults. An increase in omission errors was also associated with falls (p < 0.01) and reduced falls efficacy (p < 0.05). Upon controlling for age and gender affects, logistic regression modelling revealed that increasing variability associated with the vigilance (top-down) aspect of sustained attention was a retrospective predictor of falling (p < 0.01, OR = 1.14, 95% CI: 1.03 - 1.26) in the previous year and was weakly correlated with reduced falls efficacy in non-fallers (p = 0.07). Conclusions Greater variability in sustained attention is strongly correlated with retrospective falls and to a lesser degree with reduced falls efficacy. This cognitive measure may provide a novel and valuable biomarker for falls in older adults, potentially allowing for early detection and the implementation of preventative intervention

  9. Rewards boost sustained attention through higher effort: A value-based decision making approach.

    Science.gov (United States)

    Massar, Stijn A A; Lim, Julian; Sasmita, Karen; Chee, Michael W L

    2016-10-01

    Maintaining sustained attention over time is an effortful process limited by finite cognitive resources. Recent theories describe the role of motivation in the allocation of such resources as a decision process: the costs of effortful performance are weighed against its gains. We examined this hypothesis by combining methods from attention research and decision neuroscience. Participants first performed a sustained attention task at different levels of reward. They then performed a reward-discounting task, measuring the subjective costs of performance. Results demonstrated that higher rewards led to improved performance (Exp 1-3), and enhanced attentional effort (i.e. pupil diameter; Exp 2 & 3). Moreover, discounting curves constructed from the choice task indicated that subjects devalued rewards that came at the cost of staying vigilant for a longer duration (Exp 1 & 2). Motivation can thus boost sustained attention through increased effort, while sustained performance is regarded as a cost against which rewards are discounted. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Auditory and visual sustained attention in children with speech sound disorder.

    Science.gov (United States)

    Murphy, Cristina F B; Pagan-Neves, Luciana O; Wertzner, Haydée F; Schochat, Eliane

    2014-01-01

    Although research has demonstrated that children with specific language impairment (SLI) and reading disorder (RD) exhibit sustained attention deficits, no study has investigated sustained attention in children with speech sound disorder (SSD). Given the overlap of symptoms, such as phonological memory deficits, between these different language disorders (i.e., SLI, SSD and RD) and the relationships between working memory, attention and language processing, it is worthwhile to investigate whether deficits in sustained attention also occur in children with SSD. A total of 55 children (18 diagnosed with SSD (8.11 ± 1.231) and 37 typically developing children (8.76 ± 1.461)) were invited to participate in this study. Auditory and visual sustained-attention tasks were applied. Children with SSD performed worse on these tasks; they committed a greater number of auditory false alarms and exhibited a significant decline in performance over the course of the auditory detection task. The extent to which performance is related to auditory perceptual difficulties and probable working memory deficits is discussed. Further studies are needed to better understand the specific nature of these deficits and their clinical implications.

  11. Auditory and visual sustained attention in children with speech sound disorder.

    Directory of Open Access Journals (Sweden)

    Cristina F B Murphy

    Full Text Available Although research has demonstrated that children with specific language impairment (SLI and reading disorder (RD exhibit sustained attention deficits, no study has investigated sustained attention in children with speech sound disorder (SSD. Given the overlap of symptoms, such as phonological memory deficits, between these different language disorders (i.e., SLI, SSD and RD and the relationships between working memory, attention and language processing, it is worthwhile to investigate whether deficits in sustained attention also occur in children with SSD. A total of 55 children (18 diagnosed with SSD (8.11 ± 1.231 and 37 typically developing children (8.76 ± 1.461 were invited to participate in this study. Auditory and visual sustained-attention tasks were applied. Children with SSD performed worse on these tasks; they committed a greater number of auditory false alarms and exhibited a significant decline in performance over the course of the auditory detection task. The extent to which performance is related to auditory perceptual difficulties and probable working memory deficits is discussed. Further studies are needed to better understand the specific nature of these deficits and their clinical implications.

  12. Effects of an 8-week yoga program on sustained attention and discrimination function in children with attention deficit hyperactivity disorder

    Directory of Open Access Journals (Sweden)

    Chien-Chih Chou

    2017-01-01

    Full Text Available This study investigated whether a yoga exercise intervention influenced the sustained attention and discrimination function in children with ADHD. Forty-nine participants (mean age = 10.50 years were assigned to either a yoga exercise or a control group. Participants were given the Visual Pursuit Test and Determination Test prior to and after an eight-week exercise intervention (twice per week, 40 min per session or a control intervention. Significant improvements in accuracy rate and reaction time of the two tests were observed over time in the exercise group compared with the control group. These findings suggest that alternative therapies such as yoga exercises can be complementary to behavioral interventions for children with attention and inhibition problems. Schools and parents of children with ADHD should consider alternatives for maximizing the opportunities that children with ADHD can engage in structured yoga  exercises.

  13. Оrganizational attention deficit as sustainability indicator: assessment and management

    Directory of Open Access Journals (Sweden)

    Silvana Markovska-Simoska

    2013-12-01

    Full Text Available The aim of this paper is to contribute towards dealing with the attention indicator in a standard Pressure-State-Response (PSR framework of sustainable development. Hence, the daily information overflow is identified as a pressure variable adversely affecting the attention. This is manifested by an increased likelihood of missing key information when making decisions, diminished time for attentive reflection, difficulty in holding others’ attention, as well as by decreased ability to focus when necessary, which are symptoms of the so-called organizational attention deficit disorder - OADD. As to the state variable there were combined techniques from cognitive neuroscience and applied sciences in order to objectively measure the incidence of OADD. In particular, the use of neuropsychological procedures for objective assessment of OADD will be summarized. Namely, few attention diagnostic tests of the Amsterdam Neuropsychological Tasks Program (ANT will be considered for determining the focused, shifted and sustained attention. As intervention measure attention strengthening techniques is applied. In particular, in research were proposed the neurofeedback technique as response variable and have shown its effectiveness in coping with the OADD. This approach represents a new perspective in social psychophysiology and expands the potential applications of ANT and neurofeedback methodology. 

  14. Sustained attention and heart rate variability in children and adolescents with ADHD.

    Science.gov (United States)

    Griffiths, Kristi R; Quintana, Daniel S; Hermens, Daniel F; Spooner, Chris; Tsang, Tracey W; Clarke, Simon; Kohn, Michael R

    2017-03-01

    The autonomic nervous system (ANS) plays an important role in attention and self-regulation by modulating physiological arousal to meet environmental demands. Core symptoms of ADHD such as inattention and behavioral disinhibition may be related to dysregulation of the ANS, however previous findings have been equivocal. We examined autonomic activity and reactivity by assessing heart rate variability (HRV) in a large sample of un-medicated children and adolescents (6-19 years) with ADHD (n=229) compared to typically-developing controls (n=244) during rest and sustained attention. Four heart rate variability measures were extracted: Root mean square of successive differences between inter-beat-intervals (rMSSD), absolute high frequency (HFA) power, absolute low frequency (LFA) power and ratio of low frequency power to high frequency power (LF/HF). There were no group differences in HFA or rMSSD, even when assessing across child and adolescent groups separately, by gender or ADHD subtype. LF/HF however was higher in ADHD during both rest and sustained attention conditions, particularly in male children. Sustained attention was impaired in ADHD relative to controls, and a higher LF/HF ratio during sustained attention was associated with poorer performance in both groups. Lower rMSSD and HFA were associated with higher anxiety, oppositional behaviors and social problems, supporting prevailing theories that these measures index emotion regulation and adaptive social behavior. Different measures of heart rate variability provide important insights into the sustained attention and emotional and behavioral regulation impairments observed in ADHD and may aid in delineating ADHD pathophysiology. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. The Neural Basis of Sustained and Transient Attentional Control in Young Adults with ADHD

    Science.gov (United States)

    Banich, Marie T.; Burgess, Gregory C.; Depue, Brendan E.; Ruzic, Luka; Bidwell, L. Cinnamon; Hitt-Laustsen, Sena; Du, Yiping P.; Willcutt, Erik G.

    2009-01-01

    Differences in neural activation during performance on an attentionally demanding Stroop task were examined between 23 young adults with ADHD carefully selected to not be co-morbid for other psychiatric disorders and 23 matched controls. A hybrid blocked/single-trial design allowed for examination of more sustained vs. more transient aspects of…

  16. Reaction time, processing speed and sustained attention in schizophrenia: impact on social functioning.

    Science.gov (United States)

    Lahera, Guillermo; Ruiz, Alicia; Brañas, Antía; Vicens, María; Orozco, Arantxa

    Previous studies have linked processing speed with social cognition and functioning of patients with schizophrenia. A discriminant analysis is needed to determine the different components of this neuropsychological construct. This paper analyzes the impact of processing speed, reaction time and sustained attention on social functioning. 98 outpatients between 18 and 65 with DSM-5 diagnosis of schizophrenia, with a period of 3 months of clinical stability, were recruited. Sociodemographic and clinical data were collected, and the following variables were measured: processing speed (Trail Making Test [TMT], symbol coding [BACS], verbal fluency), simple and elective reaction time, sustained attention, recognition of facial emotions and global functioning. Processing speed (measured only through the BACS), sustained attention (CPT) and elective reaction time (but not simple) were associated with functioning. Recognizing facial emotions (FEIT) correlated significantly with scores on measures of processing speed (BACS, Animals, TMT), sustained attention (CPT) and reaction time. The linear regression model showed a significant relationship between functioning, emotion recognition (P=.015) and processing speed (P=.029). A deficit in processing speed and facial emotion recognition are associated with worse global functioning in patients with schizophrenia. Copyright © 2017 SEP y SEPB. Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Picture Naming in Typically Developing and Language-Impaired Children: The Role of Sustained Attention

    Science.gov (United States)

    Jongman, Suzanne R.; Roelofs, Ardi; Scheper, Annette R.; Meyer, Antje S.

    2017-01-01

    Background: Children with specific language impairment (SLI) have problems not only with language performance but also with sustained attention, which is the ability to maintain alertness over an extended period of time. Although there is consensus that this ability is impaired with respect to processing stimuli in the auditory perceptual…

  18. Sustained Attention during Learning Activities: An Observational Study with Pre-School Children

    Science.gov (United States)

    Lopez, Florente; Menez, Marina; Hernandez-Guzman, Laura

    2005-01-01

    The purpose of the present study was to analyse possible developmental trends in sustained attention through the pre-school period, as well as the influence of social and physical distractions. Three samples of children, one per each pre-school grade, were observed during learning activities required by the teacher. Children's behaviour was coded…

  19. Picture naming in typically developing and language-impaired children: The role of sustained attention

    NARCIS (Netherlands)

    Jongman, S.R.; Roelofs, A.P.A.; Scheper, A.R.; Meyer, A.S.

    2017-01-01

    Background: Children with specific language impairment (SLI) have problems not only with language performance but also with sustained attention, which is the ability to maintain alertness over an extended period of time. Although there is consensus that this ability is impaired with respect to

  20. A Functional Near-Infrared Spectroscopy Study of Sustained Attention to Local and Global Target Features

    Science.gov (United States)

    De Joux, Neil; Russell, Paul N.; Helton, William S.

    2013-01-01

    Despite a long history of vigilance research, the role of global and local feature discrimination in vigilance tasks has been relatively neglected. In this experiment participants performed a sustained attention task requiring either global or local shape stimuli discrimination. Reaction time to local feature discriminations was characterized by a…

  1. The effects of priming in a cued dot-probe task on appearance-related attentional biases in women.

    Science.gov (United States)

    Lane, Ben R; Mulgrew, Kate E; Mahar, Doug; White, Melanie J; Loughnan, Siobhan A

    2017-07-01

    The dot-probe task (DPT) is a reaction time measure of attentional bias. Research using this task has found inconsistent patterns of appearance-related attentional biases in women. This study examined the effects of a novel priming variation of the DPT, which incorporated additional cues into each trial of the task, on measurement of such biases. The study also examined associations between these biases and body image, a component of eating disorder symptomatology. A convenience sample of women from the general community (N = 103) completed body image measures online and attended a laboratory session to complete one of four DPTs: (1) an appearance-cued DPT containing images of thin-ideal models between each trial; (2) neutral-cued DPT containing images of forests; (3) time-delayed DPT controlling for time in place of an image; or (4) typical DPT containing only word stimuli. Women who completed the appearance-cued DPT demonstrated a stronger attentional bias for positive, but not negative, appearance words than women who completed the other DPT versions. Furthermore, for the appearance-cued and time-delayed DPTs, this bias correlated with poorer body image across several indicators (appearance evaluation, body dissatisfaction, self-evaluative salience of appearance, and state body satisfaction). Although it was unexpected that no attentional bias for negative-appearance words was found, the attentional bias for positive-appearance words may suggest that effects were driven by the ego-threat of positive-appearance words. Further research is warranted to determine whether such biases contribute to and maintain body image disturbance and disordered eating. © 2017 Wiley Periodicals, Inc.

  2. Reduced functional connectivity of fronto-parietal sustained attention networks in severe childhood abuse.

    Directory of Open Access Journals (Sweden)

    Heledd Hart

    Full Text Available Childhood maltreatment is associated with attention deficits. We examined the effect of childhood abuse and abuse-by-gene (5-HTTLPR, MAOA, FKBP5 interaction on functional brain connectivity during sustained attention in medication/drug-free adolescents. Functional connectivity was compared, using generalised psychophysiological interaction (gPPI analysis of functional magnetic resonance imaging (fMRI data, between 21 age-and gender-matched adolescents exposed to severe childhood abuse and 27 healthy controls, while they performed a parametrically modulated vigilance task requiring target detection with a progressively increasing load of sustained attention. Behaviourally, participants exposed to childhood abuse had increased omission errors compared to healthy controls. During the most challenging attention condition abused participants relative to controls exhibited reduced connectivity, with a left-hemispheric bias, in typical fronto-parietal attention networks, including dorsolateral, rostromedial and inferior prefrontal and inferior parietal regions. Abuse-related connectivity abnormalities were exacerbated in individuals homozygous for the risky C-allele of the single nucleotide polymorphism rs3800373 of the FK506 Binding Protein 5 (FKBP5 gene. Findings suggest that childhood abuse is associated with decreased functional connectivity in fronto-parietal attention networks and that the FKBP5 genotype moderates neurobiological vulnerability to abuse. These findings represent a first step towards the delineation of abuse-related neurofunctional connectivity abnormalities, which hopefully will facilitate the development of specific treatment strategies for victims of childhood maltreatment.

  3. Sustained Spatial Attention to Vibrotactile Stimulation in the Flutter Range: Relevant Brain Regions and Their Interaction

    Science.gov (United States)

    Goltz, Dominique; Pleger, Burkhard; Thiel, Sabrina; Villringer, Arno; Müller, Matthias M.

    2013-01-01

    The present functional magnetic resonance imaging (fMRI) study was designed to get a better understanding of the brain regions involved in sustained spatial attention to tactile events and to ascertain to what extent their activation was correlated. We presented continuous 20 Hz vibrotactile stimuli (range of flutter) concurrently to the left and right index fingers of healthy human volunteers. An arrow cue instructed subjects in a trial-by-trial fashion to attend to the left or right index finger and to detect rare target events that were embedded in the vibrotactile stimulation streams. We found blood oxygen level-dependent (BOLD) attentional modulation in primary somatosensory cortex (SI), mainly covering Brodmann area 1, 2, and 3b, as well as in secondary somatosensory cortex (SII), contralateral to the to-be-attended hand. Furthermore, attention to the right (dominant) hand resulted in additional BOLD modulation in left posterior insula. All of the effects were caused by an increased activation when attention was paid to the contralateral hand, except for the effects in left SI and insula. In left SI, the effect was related to a mixture of both a slight increase in activation when attention was paid to the contralateral hand as well as a slight decrease in activation when attention was paid to the ipsilateral hand (i.e., the tactile distraction condition). In contrast, the effect in left posterior insula was exclusively driven by a relative decrease in activation in the tactile distraction condition, which points to an active inhibition when tactile information is irrelevant. Finally, correlation analyses indicate a linear relationship between attention effects in intrahemispheric somatosensory cortices, since attentional modulation in SI and SII were interrelated within one hemisphere but not across hemispheres. All in all, our results provide a basis for future research on sustained attention to continuous vibrotactile stimulation in the range of flutter

  4. Combined effects of attention and motivation on visual task performance: transient and sustained motivational effects.

    Science.gov (United States)

    Engelmann, Jan B; Damaraju, Eswar; Padmala, Srikanth; Pessoa, Luiz

    2009-01-01

    We investigated how the brain integrates motivational and attentional signals by using a neuroimaging paradigm that provided separate estimates for transient cue- and target-related signals, in addition to sustained block-related responses. Participants performed a Posner-type task in which an endogenous cue predicted target location on 70% of trials, while motivation was manipulated by varying magnitude and valence of a cash incentive linked to task performance. Our findings revealed increased detection performance (d') as a function of incentive value. In parallel, brain signals revealed that increases in absolute incentive magnitude led to cue- and target-specific response modulations that were independent of sustained state effects across visual cortex, fronto-parietal regions, and subcortical regions. Interestingly, state-like effects of incentive were observed in several of these brain regions, too, suggesting that both transient and sustained fMRI signals may contribute to task performance. For both cue and block periods, the effects of administering incentives were correlated with individual trait measures of reward sensitivity. Taken together, our findings support the notion that motivation improves behavioral performance in a demanding attention task by enhancing evoked responses across a distributed set of anatomical sites, many of which have been previously implicated in attentional processing. However, the effect of motivation was not simply additive as the impact of absolute incentive was greater during invalid than valid trials in several brain regions, possibly because motivation had a larger effect on reorienting than orienting attentional mechanisms at these sites.

  5. Combined effects of attention and motivation on visual task performance: transient and sustained motivational effects

    Directory of Open Access Journals (Sweden)

    Jan B Engelmann

    2009-03-01

    Full Text Available We investigated how the brain integrates motivational and attentional signals by using a neuroimaging paradigm that provided separate estimates for transient cue- and target-related signals, in addition to sustained block-related responses. Participants performed a Posner-type task in which an endogenous cue predicted target location on 70% of trials, while motivation was manipulated by varying magnitude and valence of a cash incentive linked to task performance. Our findings revealed increased detection performance (d’ as a function of incentive value. In parallel, brain signals revealed that increases in absolute incentive magnitude led to cue- and target-specific response modulations that were independent of sustained state effects across visual cortex, fronto-parietal regions, and subcortical regions. Interestingly, state-like effects of incentive were observed in several of these brain regions, too, suggesting that both transient and sustained fMRI signals may contribute to task performance. For both cue and block periods, the effects of administering incentives were correlated with individual trait measures of reward sensitivity. Taken together, our findings support the notion that motivation improves behavioral performance in a demanding attention task by enhancing evoked responses across a distributed set of anatomical sites, many of which have been previously implicated in attentional processing. However, the effect of motivation was not simply additive as the impact of absolute incentive was greater during invalid than valid trials in several brain regions, possibly because motivation had a larger effect on reorienting than orienting attentional mechanisms at these sites.

  6. Glucose and caffeine effects on sustained attention: an exploratory fMRI study.

    Science.gov (United States)

    Serra-Grabulosa, Josep M; Adan, Ana; Falcón, Carles; Bargalló, Núria

    2010-11-01

    Caffeine and glucose can have beneficial effects on cognitive performance. However, neural basis of these effects remain unknown. Our objective was to evaluate the effects of caffeine and glucose on sustained attention, using functional magnetic resonance imaging (fMRI). Forty young right-handed, healthy, low caffeine-consuming subjects participated in the study. In a double-blind, randomised design, subjects received one of the following beverages: vehicle (water, 150 ml); vehicle plus 75 g of glucose; vehicle plus 75 mg of caffeine; vehicle plus 75 g of glucose and 75 mg of caffeine. Participants underwent two scanning fMRI sessions (before and 30 min after of the administration of the beverage). A continuous performance test was used to assess sustained attention. Participants who received combined caffeine and glucose had similar performance to the others but had a decrease in activation in the bilateral parietal and left prefrontal cortex. Since these areas have been related to the sustained attention and working memory processes, results would suggest that combined caffeine and glucose could increase the efficiency of the attentional system. However, more studies using larger samples and different levels of caffeine and glucose are necessary to better understand the combined effects of both substances. Copyright © 2010 John Wiley & Sons, Ltd.

  7. Separable sustained and selective attention factors are apparent in 5-year-old children

    DEFF Research Database (Denmark)

    Underbjerg, Mette; George, Melanie S; Thorsen, Poul

    2013-01-01

    In adults and older children, evidence consistent with relative separation between selective and sustained attention, superimposed upon generally positive inter-test correlations, has been reported. Here we examine whether this pattern is detectable in 5-year-old children from the healthy...... of attention at the age of 5 with the results reflecting a similar factor structure to that obtained in older children and adults. The results are discussed in light of contemporary models of attention function. Given the potential advantages of early intervention for attention difficulties, the findings...... population. A new test battery (TEA-Ch(J)) was adapted from measures previously used with adults and older children and administered to 172 5-year-olds. Test-retest reliability was assessed in 60 children. Ninety-eight percent of the children managed to complete all measures. Discrimination of visual...

  8. Poor sleep quality is associated with a negative cognitive bias and decreased sustained attention.

    Science.gov (United States)

    Gobin, Christina M; Banks, Jonathan B; Fins, Ana I; Tartar, Jaime L

    2015-10-01

    Poor sleep quality has been demonstrated to diminish cognitive performance, impair psychosocial functioning and alter the perception of stress. At present, however, there is little understanding of how sleep quality affects emotion processing. The aim of the present study was to determine the extent to which sleep quality, measured through the Pittsburg Sleep Quality Index, influences affective symptoms as well as the interaction between stress and performance on an emotional memory test and sustained attention task. To that end, 154 undergraduate students (mean age: 21.27 years, standard deviation = 4.03) completed a series of measures, including the Pittsburg Sleep Quality Index, the Sustained Attention to Response Task, an emotion picture recognition task and affective symptom questionnaires following either a control or physical stress manipulation, the cold pressor test. As sleep quality and psychosocial functioning differ among chronotypes, we also included chronotype and time of day as variables of interest to ensure that the effects of sleep quality on the emotional and non-emotional tasks were not attributed to these related factors. We found that poor sleep quality is related to greater depressive symptoms, anxiety and mood disturbances. While an overall relationship between global Pittsburg Sleep Quality Index score and emotion and attention measures was not supported, poor sleep quality, as an independent component, was associated with better memory for negative stimuli and a deficit in sustained attention to non-emotional stimuli. Importantly, these effects were not sensitive to stress, chronotype or time of day. Combined, these results suggest that individuals with poor sleep quality show an increase in affective symptomatology as well as a negative cognitive bias with a concomitant decrease in sustained attention to non-emotional stimuli. © 2015 European Sleep Research Society.

  9. Neurophysiological Signals of Ignoring and Attending Are Separable and Related to Performance during Sustained Intersensory Attention

    Science.gov (United States)

    Lenartowicz, Agatha; Simpson, Gregory V.; Haber, Catherine M.; Cohen, Mark S.

    2017-01-01

    The ability to attend to an input selectively while ignoring distracting sensations is thought to depend on the coordination of two processes: enhancement of target signals and attenuation of distractor signals. This implies that attending and ignoring may be dissociable neural processes and that they make separable contributions to behavioral outcomes of attention. In this study, we tested these hypotheses in the context of sustained attention by measuring neurophysiological responses to attended and ignored stimuli in a noncued, continuous, audiovisual selective attention task. We compared these against responses during a passive control to quantify effects of attending and ignoring separately. In both sensory modalities, responses to ignored stimuli were attenuated relative to a passive control, whereas responses to attended stimuli were enhanced. The scalp topographies and brain activations of these modulatory effects were consistent with the sensory regions that process each modality. They also included parietal and prefrontal activations that suggest these effects arise from interactions between top–down and sensory cortices. Most importantly, we found that both attending and ignoring processes contributed to task accuracy and that these effects were not correlated—suggesting unique neural trajectories. This conclusion was supported by the novel observation that attending and ignoring differed in timing and in active cortical regions. The data provide direct evidence for the separable contributions of attending and ignoring to behavioral outcomes of attention control during sustained intersensory attention. PMID:24666167

  10. Visual memory and sustained attention impairment in youths with autism spectrum disorders.

    Science.gov (United States)

    Chien, Y-L; Gau, S S-F; Shang, C-Y; Chiu, Y-N; Tsai, W-C; Wu, Y-Y

    2015-08-01

    An uneven neurocognitive profile is a hallmark of autism spectrum disorder (ASD). Studies focusing on the visual memory performance in ASD have shown controversial results. We investigated visual memory and sustained attention in youths with ASD and typically developing (TD) youths. We recruited 143 pairs of youths with ASD (males 93.7%; mean age 13.1, s.d. 3.5 years) and age- and sex-matched TD youths. The ASD group consisted of 67 youths with autistic disorder (autism) and 76 with Asperger's disorder (AS) based on the DSM-IV criteria. They were assessed using the Cambridge Neuropsychological Test Automated Battery involving the visual memory [spatial recognition memory (SRM), delayed matching to sample (DMS), paired associates learning (PAL)] and sustained attention (rapid visual information processing; RVP). Youths with ASD performed significantly worse than TD youths on most of the tasks; the significance disappeared in the superior intelligence quotient (IQ) subgroup. The response latency on the tasks did not differ between the ASD and TD groups. Age had significant main effects on SRM, DMS, RVP and part of PAL tasks and had an interaction with diagnosis in DMS and RVP performance. There was no significant difference between autism and AS on visual tasks. Our findings implied that youths with ASD had a wide range of visual memory and sustained attention impairment that was moderated by age and IQ, which supports temporal and frontal lobe dysfunction in ASD. The lack of difference between autism and AS implies that visual memory and sustained attention cannot distinguish these two ASD subtypes, which supports DSM-5 ASD criteria.

  11. Dissociable Decoding of Spatial Attention and Working Memory from EEG Oscillations and Sustained Potentials.

    Science.gov (United States)

    Bae, Gi-Yeul; Luck, Steven J

    2017-11-22

    In human scalp EEG recordings, both sustained potentials and alpha-band oscillations are present during the delay period of working memory tasks and may therefore reflect the representation of information in working memory. However, these signals may instead reflect support mechanisms rather than the actual contents of memory. In particular, alpha-band oscillations have been tightly tied to spatial attention and may not reflect location-independent memory representations per se. To determine how sustained and oscillating EEG signals are related to attention and working memory, we attempted to decode which of 16 orientations was being held in working memory by human observers (both women and men). We found that sustained EEG activity could be used to decode the remembered orientation of a stimulus, even when the orientation of the stimulus varied independently of its location. Alpha-band oscillations also carried clear information about the location of the stimulus, but they provided little or no information about orientation independently of location. Thus, sustained potentials contain information about the object properties being maintained in working memory, consistent with previous evidence of a tight link between these potentials and working memory capacity. In contrast, alpha-band oscillations primarily carry location information, consistent with their link to spatial attention.Significance StatementWorking memory plays a key role in cognition, and working memory is impaired in several neurological and psychiatric disorders. Previous research has suggested that human scalp EEG recordings contain signals that reflect the neural representation of information in working memory. However, to conclude that a neural signal actually represents the object being remembered, it is necessary to show that the signal contains fine-grained information about that object. Here, we show that sustained voltages in human EEG recordings contain fine-grained information about the

  12. Some participants may be better than others: sustained attention and motivation are higher early in semester.

    Science.gov (United States)

    Nicholls, Michael E R; Loveless, Kellie M; Thomas, Nicole A; Loetscher, Tobias; Churches, Owen

    2015-01-01

    Many studies use multiexperiment designs where experiments are carried out at different times of semester. When comparing between experiments, the data may be confounded by between-participants effects related to motivation. Research indicates that course-credit participants who engage in research early in semester have different personality and performance characteristics compared to those tested late in semester. This study examined whether the semester effect is caused by internal (inherent motivation of the participant) or external (looming exams, essays) factors. To do this, sustained attention and intrinsic/extrinsic motivation was measured in groups of course-credit (n = 40) and paid (n = 40) participants early and late in semester. While there was no difference in sustained attention between the groups early in semester, the course-credit group performed significantly worse late in semester. The course-credit group also showed a significant decrease in intrinsic motivation with time whereas the paid participants showed no change. Because changes were not seen for both groups, the semester difference cannot be due to external factors. Instead, the data demonstrate that course-credit participants who engage early have high sustained attention and intrinsic motivation compared to their late counterparts, who leave their participation to the last minute. Researchers who use multiexperimental designs across semester need to control for these effects--perhaps by using paid participants who do not vary across semester.

  13. Sustained attentional states require distinct temporal involvement of the dorsal and ventral medial prefrontal cortex

    Directory of Open Access Journals (Sweden)

    Antonio Luchicchi

    2016-08-01

    Full Text Available Attending the sensory environment for cue detection is a cognitive operation that occurs on a time scale of seconds. The dorsal and ventral medial prefrontal cortex (mPFC contribute to separate aspects of attentional processing. Pyramidal neurons in different parts of the mPFC are active during cognitive behavior, yet whether this activity is causally underlying attentional processing is not known. We aimed to determine the precise temporal requirements for activation of the mPFC subregions during the seconds prior to cue detection. To test this, we used optogenetic silencing of dorsal or ventral mPFC pyramidal neurons at defined time windows during a sustained attentional state. We find that the requirement of ventral mPFC pyramidal neuron activity is strictly time-locked to stimulus detection. Inhibiting the ventral mPFC two seconds before or during cue presentation reduces response accuracy and hampers behavioral inhibition. The requirement for dorsal mPFC activity on the other hand is temporally more loosely related to a preparatory attentional state, and short lapses in pyramidal neuron activity in dorsal mPFC do not affect performance. This only occurs when the dorsal mPFC is inhibited during the entire preparatory period. Together, our results reveal that a dissociable temporal recruitment of ventral and dorsal mPFC is required during attentional processing.

  14. Sustained Attentional States Require Distinct Temporal Involvement of the Dorsal and Ventral Medial Prefrontal Cortex.

    Science.gov (United States)

    Luchicchi, Antonio; Mnie-Filali, Ouissame; Terra, Huub; Bruinsma, Bastiaan; de Kloet, Sybren F; Obermayer, Joshua; Heistek, Tim S; de Haan, Roel; de Kock, Christiaan P J; Deisseroth, Karl; Pattij, Tommy; Mansvelder, Huibert D

    2016-01-01

    Attending the sensory environment for cue detection is a cognitive operation that occurs on a time scale of seconds. The dorsal and ventral medial prefrontal cortex (mPFC) contribute to separate aspects of attentional processing. Pyramidal neurons in different parts of the mPFC are active during cognitive behavior, yet whether this activity is causally underlying attentional processing is not known. We aimed to determine the precise temporal requirements for activation of the mPFC subregions during the seconds prior to cue detection. To test this, we used optogenetic silencing of dorsal or ventral mPFC pyramidal neurons at defined time windows during a sustained attentional state. We find that the requirement of ventral mPFC pyramidal neuron activity is strictly time-locked to stimulus detection. Inhibiting the ventral mPFC 2 s before or during cue presentation reduces response accuracy and hampers behavioral inhibition. The requirement for dorsal mPFC activity on the other hand is temporally more loosely related to a preparatory attentional state, and short lapses in pyramidal neuron activity in dorsal mPFC do not affect performance. This only occurs when the dorsal mPFC is inhibited during the entire preparatory period. Together, our results reveal that a dissociable temporal recruitment of ventral and dorsal mPFC is required during attentional processing.

  15. Shared and disorder-specific task-positive and default mode network dysfunctions during sustained attention in paediatric Attention-Deficit/Hyperactivity Disorder and obsessive/compulsive disorder

    Directory of Open Access Journals (Sweden)

    Luke J. Norman

    2017-01-01

    Full Text Available Patients with Attention-Deficit/Hyperactivity Disorder (ADHD and obsessive/compulsive disorder (OCD share problems with sustained attention, and are proposed to share deficits in switching between default mode and task positive networks. The aim of this study was to investigate shared and disorder-specific brain activation abnormalities during sustained attention in the two disorders. Twenty boys with ADHD, 20 boys with OCD and 20 age-matched healthy controls aged between 12 and 18 years completed a functional magnetic resonance imaging (fMRI version of a parametrically modulated sustained attention task with a progressively increasing sustained attention load. Performance and brain activation were compared between groups. Only ADHD patients were impaired in performance. Group by sustained attention load interaction effects showed that OCD patients had disorder-specific middle anterior cingulate underactivation relative to controls and ADHD patients, while ADHD patients showed disorder-specific underactivation in left dorsolateral prefrontal cortex/dorsal inferior frontal gyrus (IFG. ADHD and OCD patients shared left insula/ventral IFG underactivation and increased activation in posterior default mode network relative to controls, but had disorder-specific overactivation in anterior default mode regions, in dorsal anterior cingulate for ADHD and in anterior ventromedial prefrontal cortex for OCD. In sum, ADHD and OCD patients showed mostly disorder-specific patterns of brain abnormalities in both task positive salience/ventral attention networks with lateral frontal deficits in ADHD and middle ACC deficits in OCD, as well as in their deactivation patterns in medial frontal DMN regions. The findings suggest that attention performance in the two disorders is underpinned by disorder-specific activation patterns.

  16. The sleep, subjective fatigue, and sustained attention of commercial airline pilots during an international pattern.

    Science.gov (United States)

    Petrilli, Renée M; Roach, Gregory D; Dawson, Drew; Lamond, Nicole

    2006-01-01

    International commercial airline pilots may experience heightened fatigue due to irregular sleep schedules, long duty days, night flying, and multiple time zone changes. Importantly, current commercial airline flight and duty time regulations are based on work/rest factors and not sleep/wake factors. Consequently, the primary aim of the current study was to investigate pilots' amount of sleep, subjective fatigue, and sustained attention before and after international flights. A secondary aim was to determine whether prior sleep and/or duty history predicted pilots' subjective fatigue and sustained attention during the international flights. Nineteen pilots (ten captains, nine first officers; mean age: 47.42+/-7.52 years) participated. Pilots wore wrist activity monitors and completed sleep and duty diaries during a return pattern from Australia to Europe via Asia. The pattern included four flights: Australia-Asia, Asia-Europe, Europe-Asia, and Asia-Australia. Before and after each flight, pilots completed a 5 min PalmPilot-based psychomotor vigilance task (PVT) and self-rated their level of fatigue using the Samn-Perelli Fatigue Checklist. Separate repeated-measures ANOVAs were used to determine the impact of stage of flight and flight sector on the pilots' sleep in the prior 24 h, self-rated fatigue, and PVT mean response speed. Linear mixed model regression analyses were conducted to examine the impact of sleep in the prior 24 h, prior wake, duty length, and flight sector on pilots' self-rated fatigue and sustained attention before and after the international flights. A significant main effect of stage of flight was found for sleep in the prior 24 h, self-rated fatigue, and mean response speed (all p pilots should be taken into account in the development of flight and duty time regulations.

  17. Mathematical Physics Framework SustainingNatural Anticipation and Selection of Attention

    Directory of Open Access Journals (Sweden)

    Alfons Salden

    2005-04-01

    Full Text Available An ambient intelligent environment is definitely a prerequisite for anticipating the needs and catching the attention of systems. But how to endow such an environment with natural anticipatory and attentive features is still a hardly ever properly addressed question. Before providing a roadmap towards such an ambient intelligent environment we first give cognitive-ergonomic accounts for how natural anticipation and selection of attention (NASA emerge in living organisms. In particular, we describe why, when and how exploratory and goal-directed acts by living organisms are controlled while optimizing their changing and limited structural and functional capabilities of multimodal sensor, cognitive and actuator systems. Next, we describe how NASA can be embedded and embodied in sustainable intelligent multimodal systems (SIMS. Such systems allow an ambient intelligent environment to (self- interact taking its contexts into account. In addition, collective intelligent agents (CIA distribute, store, extend, maintain, optimize, diversify and sustain the NASA embedded and embodied in the ambient intelligent environment. Finally, we present the basic ingredients of a mathematical-physical framework for empirically modeling and sustaining NASA within SIMS by CIA in an ambient intelligent environment. An environment which is modeled this way, robustly and reliably over time aligns multi-sensor detection and fusion; multimodal fusion, dialogue planning and fission; multi actuator fission, rendering and presentation schemes. NASA residing in such an environment are then active within every phase of perception-decision-action cycles, and are gauged and renormalized to its physics. After determining and assessing across several evolutionary dynamic scales appropriate fitness, utility and measures, NASA can be realized by reinforcement learning and self-organization.

  18. Sustained attention is associated with error processing impairment: evidence from mental fatigue study in four-choice reaction time task

    National Research Council Canada - National Science Library

    Xiao, Yi; Ma, Feng; Lv, Yixuan; Cai, Gui; Teng, Peng; Xu, FengGang; Chen, Shanguang

    2015-01-01

    .... In this study, we examined how error-related negativity (ERN) of a four-choice reaction time task was reduced in the mental fatigue condition and investigated the role of sustained attention in error processing...

  19. Human performance under sustained operations and acute sleep deprivation conditions: toward a model of controlled attention.

    Science.gov (United States)

    Pilcher, June J; Band, David; Odle-Dusseau, Heather N; Muth, Eric R

    2007-05-01

    Although a number of studies have examined the effects of sleep deprivation on performance, the results are not easily explained. The purpose of the current study was to examine the effects of sustained operations and acute sleep deprivation on tasks that require a wide range of information processing. The current study also provided preliminary data on the use of the controlled attention model to better understand the effects of sleep deprivation. There were 24 college students who were paid to remain awake for one night and complete a variety of cognitive and vigilance tasks. Each task was administered four times during the night, once in each testing session (17:30-21:30, 21:45-01:45, 02:30-06:30, and 06:45-10:45). All tasks were counterbalanced across the testing sessions. The data were converted to z-scores and repeated-measures ANOVAs were completed. Performance did not significantly decrease on the more complex cognitive tasks over the night of sleep deprivation. Performance on the vigilance tasks decreased significantly across the night. Examining the characteristics of the cognitive tasks indicated that although they required different types of processing, they encouraged the participants to remain attentive to and engaged in the task. In contrast, the vigilance tasks were less intrinsically interesting and engaging. Thus, it seems likely that the participants were less capable of maintaining attention on the vigilance tasks than the cognitive tasks. These results indicate that a controlled attention model may be useful in better understanding the effects of sustained operations and sleep deprivation on performance.

  20. EEG indices correlate with sustained attention performance in patients affected by diffuse axonal injury.

    Science.gov (United States)

    Coelli, Stefania; Barbieri, Riccardo; Reni, Gianluigi; Zucca, Claudio; Bianchi, Anna Maria

    2017-11-09

    The aim of this study is to assess the ability of EEG-based indices in providing relevant information about cognitive engagement level during the execution of a clinical sustained attention (SA) test in healthy volunteers and DAI (diffused axonal injury)-affected patients. We computed three continuous power-based engagement indices (P β /P α , 1/P α , and P β / (P α + P θ )) from EEG recordings in a control group (n = 7) and seven DAI-affected patients executing a 10-min Conners' "not-X" continuous performance test (CPT). A correlation analysis was performed in order to investigate the existence of relations between the EEG metrics and behavioral parameters in both the populations. P β /P α and 1/P α indices were found to be correlated with reaction times in both groups while P β / (P α + P θ ) and P β /P α also correlated with the errors rate for DAI patients. In line with previous studies, time course fluctuations revealed a first strong decrease of attention after 2 min from the beginning of the test and a final fading at the end. Our results provide evidence that EEG-derived indices extraction and evaluation during SA tasks are helpful in the assessment of attention level in healthy subjects and DAI patients, offering motivations for including EEG monitoring in cognitive rehabilitation practice. Graphical abstract Three EEG-derived indices were computed from four electrodes montages in a population of seven healthy volunteers and a group of seven DAI-affected patients. Results show a significant correlation between the time course of the indices and behavioral parameters, thus demonstrating their usefulness in monitoring mental engagement level during a sustained attention task.

  1. Impaired Limbic Cortico-Striatal Structure and Sustained Visual Attention in a Rodent Model of Schizophrenia

    Science.gov (United States)

    Barnes, Samuel A.; Sawiak, Stephen J.; Caprioli, Daniele; Jupp, Bianca; Buonincontri, Guido; Mar, Adam C.; Harte, Michael K.; Fletcher, Paul C.; Robbins, Trevor W.; Neill, Jo C.

    2015-01-01

    Background: N-methyl-d-aspartate receptor (NMDAR) dysfunction is thought to contribute to the pathophysiology of schizophrenia. Accordingly, NMDAR antagonists such as phencyclidine (PCP) are used widely in experimental animals to model cognitive impairment associated with this disorder. However, it is unclear whether PCP disrupts the structural integrity of brain areas relevant to the profile of cognitive impairment in schizophrenia. Methods: Here we used high-resolution magnetic resonance imaging and voxel-based morphometry to investigate structural alterations associated with sub-chronic PCP treatment in rats. Results: Sub-chronic exposure of rats to PCP (5mg/kg twice daily for 7 days) impaired sustained visual attention on a 5-choice serial reaction time task, notably when the attentional load was increased. In contrast, sub-chronic PCP had no significant effect on the attentional filtering of a pre-pulse auditory stimulus in an acoustic startle paradigm. Voxel-based morphometry revealed significantly reduced grey matter density bilaterally in the hippocampus, anterior cingulate cortex, ventral striatum, and amygdala. PCP-treated rats also exhibited reduced cortical thickness in the insular cortex. Conclusions: These findings demonstrate that sub-chronic NMDA receptor antagonism is sufficient to produce highly-localized morphological abnormalities in brain areas implicated in the pathogenesis of schizophrenia. Furthermore, PCP exposure resulted in dissociable impairments in attentional function. PMID:25552430

  2. The role of sustained attention and display medium in reading comprehension among adolescents with ADHD and without it.

    Science.gov (United States)

    Stern, Pnina; Shalev, Lilach

    2013-01-01

    Difficulties in reading comprehension are common in children and adolescents with Attention Deficit/Hyperactivity Disorder (ADHD). The current study aimed at investigating the relation between sustained attention and reading comprehension among adolescents with and without ADHD. Another goal was to examine the impact of two manipulations of the text on the efficiency of reading comprehension: Spacing (standard- vs. double-spacing) and Type of presentation (computer screen vs. hard copy). Reading comprehension of two groups of adolescents (participants with ADHD and normal controls) was assessed and compared in four different conditions (standard printed, spaced printed, standard on computer screen, spaced on computer screen). In addition, participants completed a visual sustained attention task. Significant differences in reading comprehension and in sustained attention were obtained between the two groups. Also, a significant correlation was obtained between sustained attention and reading comprehension. Moreover, a significant interaction was revealed between presentation-type, spacing and level of sustained attention on reading comprehension. Implications for reading intervention and the importance of early assessment of attention functioning are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Text-speak processing and the sustained attention to response task.

    Science.gov (United States)

    Head, James; Russell, Paul N; Dorahy, Martin J; Neumann, Ewald; Helton, William S

    2012-01-01

    We examined performance in a sustained attention to response task (SART) (Experiment 1) and a more traditionally formatted vigilance task (Experiment 2) using novel word stimuli (text-speak) and normally spelt words. This enabled us to address whether the SART is a better measure of sustained attention or of response strategy, and to investigate the cognitive demands of text-speak processing. In Experiment 1, 72 participants completed a subset (text-speak) and a word SART, as well as a self-reported text experience questionnaire. Those who reported more proficiency and experience with text-speak made more errors on the subset SART, but this appeared to be due to their increase in response speed. This did not occur in the word SART. In Experiment 2, 14 participants completed high No-Go, low-Go (more traditional response format) versions of these tasks to further investigate the cognitive demands of text-speak processing. Response latency increased over periods of watch only for the text-speak task, not for the word task. The results of Experiment 1 support the perspective that the SART is highly sensitive to response strategy, and the results of both experiments together indicate target detection tasks may be a novel way of investigating the cognitive demands of text-speak processing.

  4. Effect of orthostatic hypotension on sustained attention in patients with autonomic failure.

    Science.gov (United States)

    van Vliet, P; Hilt, A D; Thijs, R D; van Dijk, J G

    2016-02-01

    Orthostatic hypotension has been associated with impaired cognitive function, but cognitive function during orthostatic hypotension has hardly been studied. We studied the effect of orthostatic hypotension, induced by head-up tilt (HUT), on sustained attention in patients with autonomic failure. We studied the sustained attention to response task (SART) in the supine position and during HUT in 10 patients with autonomic failure and 10 age-matched and sex-matched controls. To avoid syncope, the tilting angle was tailored to patients to reach a stable systolic blood pressure below 100 mm Hg. Controls were all tilted at an angle of 60°. Cerebral blood flow velocity, blood pressure and heart rate were measured continuously. In patients, systolic blood pressure was 61.4 mm Hg lower during HUT than in the supine position (pattention. This might partly be explained by the observation that SART performance led to a blood pressure increase. Moreover, the upright position was associated with better performance in controls and, to a lesser extent, also in patients. 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/

  5. Impact of combined intermittent preventive treatment of malaria and helminths on anaemia, sustained attention, and recall in Northern Ghanaian schoolchildren

    DEFF Research Database (Denmark)

    Opoku, Ernest Cudjoe; Olsen, Annette; Browne, Edmund

    2016-01-01

    to measure haemoglobin (Hb), while the code transmission test (CTT), adapted from the Test of Everyday Attention for Children (TEA-Ch), was used to measure sustained attention and recall before-and-after interventions in June 2011 and June 2012. RESULTS: We observed significant malaria parasite prevalence...

  6. The power of competition: Effects of social motivation on attention, sustained physical effort, and learning.

    Science.gov (United States)

    DiMenichi, Brynne C; Tricomi, Elizabeth

    2015-01-01

    Competition has often been implicated as a means to improve effort-based learning and attention. Two experiments examined the effects of competition on effort and memory. In Experiment 1, participants completed a physical effort task in which they were rewarded for winning an overall percentage, or for winning a competition they believed was against another player. In Experiment 2, participants completed a memory task in which they were rewarded for remembering an overall percentage of shapes, or more shapes than a "competitor." We found that, in the physical effort task, participants demonstrated faster reaction times (RTs)-a previous indicator of increased attention-in the competitive environment. Moreover, individual differences predicted the salience of competition's effect. Furthermore, male participants showed faster RTs and greater sustained effort as a result of a competitive environment, suggesting that males may be more affected by competition in physical effort tasks. However, in Experiment 2, participants remembered fewer shapes when competing, and later recalled less of these shapes during a post-test, suggesting that competition was harmful in our memory task. The different results from these two experiments suggest that competition can improve attention in a physical effort task, yet caution the use of competition in memory tasks.

  7. Sustainable microalgae for the simultaneous synthesis of carbon quantum dots for cellular imaging and porous carbon for CO2capture.

    Science.gov (United States)

    Guo, Li-Ping; Zhang, Yan; Li, Wen-Cui

    2017-05-01

    Microalgae biomass is a sustainable source with the potential to produce a range of products. However, there is currently a lack of practical and functional processes to enable the high-efficiency utilization of the microalgae. We report here a hydrothermal process to maximize the utilizability of microalgae biomass. Specifically, our concept involves the simultaneous conversion of microalgae to (i) hydrophilic and stable carbon quantum dots and (ii) porous carbon. The synthesis is easily scalable and eco-friendly. The microalgae-derived carbon quantum dots possess a strong two-photon fluorescence property, have a low cytotoxicity and an efficient cellular uptake, and show potential for high contrast bioimaging. The microalgae-based porous carbons show excellent CO 2 capture capacities of 6.9 and 4.2mmolg -1 at 0 and 25°C respectively, primarily due to the high micropore volume (0.59cm 3 g -1 ) and large specific surface area (1396m 2 g -1 ). Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Examining the Relative Contribution of Memory Updating, Attention Focus Switching, and Sustained Attention to Children’s Verbal Working Memory Span

    Directory of Open Access Journals (Sweden)

    Beula M. Magimairaj

    2013-01-01

    Full Text Available Whereas considerable developmental memory research has examined the contributions of short-term memory, processing efficiency, retention duration, and scope of attention to complex memory span, little is known about the influence of controlled attention. The present study investigated the relative influence of three understudied attention mechanisms on the verbal working memory span of school-age children: memory updating; attention focus switching; and sustained attention. Results of general linear modeling revealed that, after controlling for age, only updating accuracy emerged as a significant predictor of verbal working memory span. Memory updating speed (that subsumed attention focus switching speed also contributed but was mediated by age. The results extend the developmental memory literature by implicating the mechanism of memory updating and developmental improvement in speed of attention focus switching and updating as critical contributors to children’s verbal working memory. Theoretically, the results provide substantively new information about the role of domain-general executive attention in children’s verbal working memory.

  9. Abnormalities of resting state functional connectivity are related to sustained attention deficits in MS.

    Directory of Open Access Journals (Sweden)

    Marisa Loitfelder

    Full Text Available OBJECTIVES: Resting state (RS functional MRI recently identified default network abnormalities related to cognitive impairment in MS. fMRI can also be used to map functional connectivity (FC while the brain is at rest and not adhered to a specific task. Given the importance of the anterior cingulate cortex (ACC for higher executive functioning in MS, we here used the ACC as seed-point to test for differences and similarities in RS-FC related to sustained attention between MS patients and controls. DESIGN: Block-design rest phases of 3 Tesla fMRI data were analyzed to assess RS-FC in 31 patients (10 clinically isolated syndromes, 16 relapsing-remitting, 5 secondary progressive MS and 31 age- and gender matched healthy controls (HC. Participants underwent extensive cognitive testing. OBSERVATIONS: In both groups, signal changes in several brain areas demonstrated significant correlation with RS-activity in the ACC. These comprised the posterior cingulate cortex (PCC, insular cortices, the right caudate, right middle temporal gyrus, angular gyri, the right hippocampus, and the cerebellum. Compared to HC, patients showed increased FC between the ACC and the left angular gyrus, left PCC, and right postcentral gyrus. Better cognitive performance in the patients was associated with increased FC to the cerebellum, middle temporal gyrus, occipital pole, and the angular gyrus. CONCLUSION: We provide evidence for adaptive changes in RS-FC in MS patients compared to HC in a sustained attention network. These results extend and partly mirror findings of task-related fMRI, suggesting FC may increase our understanding of cognitive dysfunction in MS.

  10. Rehabilitative training of preterm children’s attention: a study on sustainability

    Directory of Open Access Journals (Sweden)

    Giovanna Perricone

    2012-10-01

    Full Text Available This article is concerned with the description of rehabilitative training aimed at severely and moderately preterm children at preschool age who display impairments of processes of selective attention, self-control and problem solving and who are at risk of Attention Deficit Hyperactivity Disorders. In line with a perspective of field study suggested by pediatric psychology, the treatment calls for the involvement of parents, teachers, neonatologists and children’s reference pediatricians. To be more precise, it is a study aimed at investigating the sustainability of the training path in terms of impact and transformative valence of the focalised processes. Involved in the study was a group of 55 healthy preterm children (35 moderately preterm children and 20 severely preterm children at mean age of 5.2 years attending the third year of infancy school; a group of 55 mothers; a group of 15 pediatricians; a group of 5 neonatologists and one of 10 teachers. Specific questionnaires (the IPDAG and IPDDAI were administered to parents and teachers before and after the training sessions to detect the transformation of the focalised processes. According to a modality of continuous observation during the activities, the trainer used techniques of narrative (the critical incident technique and descriptive (encoding scheme observation. A checklist to detect the participation of adults was used. It was structured as follows: presence, production and aftermath of the effects of the personal intervention with child. A telephone follow-up was performed three months after the end of training to detect the involved adults’ considerations about the stability of promoted changes. Data show good levels of sustainability of the proposed training.

  11. Embodied niche construction in the hominin lineage: semiotic structure and sustained attention in human embodied cognition.

    Science.gov (United States)

    Stutz, Aaron J

    2014-01-01

    Human evolution unfolded through a rather distinctive, dynamically constructed ecological niche. The human niche is not only generally terrestrial in habitat, while being flexibly and extensively heterotrophic in food-web connections. It is also defined by semiotically structured and structuring embodied cognitive interfaces, connecting the individual organism with the wider environment. The embodied dimensions of niche-population co-evolution have long involved semiotic system construction, which I hypothesize to be an evolutionarily primitive aspect of learning and higher-level cognitive integration and attention in the great apes and humans alike. A clearly pre-linguistic form of semiotic cognitive structuration is suggested to involve recursively learned and constructed object icons. Higher-level cognitive iconic representation of visually, auditorily, or haptically perceived extrasomatic objects would be learned and evoked through indexical connections to proprioceptive and affective somatic states. Thus, private cognitive signs would be defined, not only by their learned and perceived extrasomatic referents, but also by their associations to iconically represented somatic states. This evolutionary modification of animal associative learning is suggested to be adaptive in ecological niches occupied by long-lived, large-bodied ape species, facilitating memory construction and recall in highly varied foraging and social contexts, while sustaining selective attention during goal-directed behavioral sequences. The embodied niche construction (ENC) hypothesis of human evolution posits that in the early hominin lineage, natural selection further modified the ancestral ape semiotic adaptations, favoring the recursive structuration of concise iconic narratives of embodied interaction with the environment.

  12. The power of competition: Effects of social motivation on attention, sustained physical effort, and learning

    Science.gov (United States)

    DiMenichi, Brynne C.; Tricomi, Elizabeth

    2015-01-01

    Competition has often been implicated as a means to improve effort-based learning and attention. Two experiments examined the effects of competition on effort and memory. In Experiment 1, participants completed a physical effort task in which they were rewarded for winning an overall percentage, or for winning a competition they believed was against another player. In Experiment 2, participants completed a memory task in which they were rewarded for remembering an overall percentage of shapes, or more shapes than a “competitor.” We found that, in the physical effort task, participants demonstrated faster reaction times (RTs)—a previous indicator of increased attention—in the competitive environment. Moreover, individual differences predicted the salience of competition’s effect. Furthermore, male participants showed faster RTs and greater sustained effort as a result of a competitive environment, suggesting that males may be more affected by competition in physical effort tasks. However, in Experiment 2, participants remembered fewer shapes when competing, and later recalled less of these shapes during a post-test, suggesting that competition was harmful in our memory task. The different results from these two experiments suggest that competition can improve attention in a physical effort task, yet caution the use of competition in memory tasks. PMID:26388801

  13. Impulsiveness, overactivity, and poorer sustained attention improve by chronic treatment with low doses of l-amphetamine in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD).

    Science.gov (United States)

    Sagvolden, Terje

    2011-03-30

    ADHD is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Overactivity, impulsiveness, and inattentiveness are presently regarded as the main clinical symptoms. There is no biological marker, but there is considerable evidence to suggest that ADHD behavior is associated with poor dopaminergic and noradrenergic modulation of neuronal circuits that involve the frontal lobes. The best validated animal model of ADHD, the Spontaneously Hypertensive Rat (SHR), shows pronounced overactivity, impulsiveness, and deficient sustained attention. The primary objective of the present research was to investigate behavioral effects of a range of doses of chronic l-amphetamine on ADHD-like symptoms in the SHR. The present study tested the behavioral effects of 0.75 and 2.2 mg l-amphetamine base/kg i.p. in male SHRs and their controls, the Wistar Kyoto rat (WKY). ADHD-like behavior was tested with a visual discrimination task measuring overactivity, impulsiveness and inattentiveness. The striking impulsiveness, overactivity, and poorer sustained attention seen during baseline conditions in the SHR were improved by chronic treatment with l-amphetamine. The dose-response curves were, however, different for the different behaviors. Most significantly, the 0.75 mg/kg dose of l-amphetamine improved sustained attention without reducing overactivity and impulsiveness. The 2.2 mg/kg dose improved sustained attention as well as reduced SHR overactivity and impulsiveness. The effects of l-amphetamine to reduce the behavioral symptoms of ADHD in the SHR were maintained over the 14 days of daily dosing with no evidence of tolerance developing.

  14. A comparison between effectiveness of three types of music on memory activity and sustained attention in schizophrenic patients

    OpenAIRE

    Narges bahmany; Karamatollah Zandi ghashghaee; Sadrollah Khosravi

    2014-01-01

    Background: schizophrenia is a psychiatric disorder in which a lot of cognitive functions including memory, attention, motor skills, executive functions and intelligence are compromised. Numerous empirical studies showed that schizophrenic patients have problem in sustain retention and memory activity. The objective of this study was a comparison between effectiveness of three types of music on memory activity and sustain retention in schizophrenic patients. Material and Methods: A total of 6...

  15. Effects of one night of induced night-wakings versus sleep restriction on sustained attention and mood: a pilot study.

    Science.gov (United States)

    Kahn, Michal; Fridenson, Shimrit; Lerer, Reut; Bar-Haim, Yair; Sadeh, Avi

    2014-07-01

    Despite their high prevalence in daily life, repeated night-wakings and their cognitive and emotional consequences have received less research attention compared to other types of sleep disturbances. Our aim was to experimentally compare the effects of one night of induced infrequent night-wakings (of ∼15 min, each requiring a purposeful response) and sleep restriction on sustained attention and mood in young adults. In a within-between subjects counterbalanced design, 61 healthy adults (40 females; aged 20-29 years) underwent home assessments of sustained attention and self-reported mood at two times: after a normal (control) sleep night, and after a night of either sleep restriction (4h in bed) or induced night-wakings (four prolonged awakenings across 8h in bed). Sleep was monitored using actigraphy and sleep diaries. Sustained attention was assessed using an online continuous performance test (OCPT), and mood was reported online using the Profile of Mood States (POMS). Actigraphic data revealed good compliance with experimental sleep requirements. Induced night-wakings and sleep restriction both resulted in more OCPT omission and commission errors, and in increased depression, fatigue and confusion levels and reduced vigor compared to the normal sleep night. Moreover, there were no significant differences between the consequences of induced awakenings and sleep restriction. Our pilot study indicates that, similar to sleep restriction, one night of life-like repeated night-wakings negatively affects mood and sustained attention. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. No sustained attention differences in a longitudinal randomized trial comparing mindfulness based stress reduction versus active control.

    Directory of Open Access Journals (Sweden)

    Donal G MacCoon

    Full Text Available Mindfulness Based Stress Reduction (MBSR is a secular form of meditation training. The vast majority of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. Previous studies have found that meditation training over several months is associated with improvements in cognitive control and attention.We used a visual continuous performance task (CPT to test the effects of eight weeks of mindfulness training on sustained attention by comparing MBSR to the Health Enhancement Program (HEP, a structurally equivalent, active control condition in a randomized, longitudinal design (ClinicalTrials.gov, NCT01301105 focusing on a non-clinical population typical of MBSR participants. Researchers were blind to group assignment. 63 community participants were randomized to either MBSR (n = 31 or HEP (n = 32. CPT analyses were conducted on 29 MBSR participants and 25 HEP participants. We predicted that MBSR would improve visual discrimination ability and sustained attention over time on the CPT compared to HEP, with more home practice associated with greater improvements. Our hypotheses were not confirmed but we did find some evidence for improved visual discrimination similar to effects in partial replication of other research. Our study had sufficient power to demonstrate that intervention groups do not differ in their improvement over time in sustained attention performance. One of our primary predictions concerning the effects of intervention on attentional fatigue was significant but not interpretable.Attentional sensitivity is not affected by mindfulness practice as taught in MBSR, but it is unclear whether mindfulness might positively affect another aspect of attention, vigilance. These results also highlight the relevant procedural modifications required by future research to correctly investigate the role of sustained attention in similar samples.ClinicalTrials.gov, NCT

  17. Effective connectivity of ascending and descending frontal-thalamic pathways during sustained attention: Complex brain network interactions in adolescence

    OpenAIRE

    Jagtap, Pranav; Diwadkar, Vaibhav A.

    2016-01-01

    Frontal-thalamic interactions are crucial for bottom-up gating and top-down control, yet have not been well studied from brain network perspectives. We applied network modeling of fMRI signals (Dynamic Causal Modeling; DCM) to investigate frontal-thalamic interactions during an attention task with parametrically varying levels of demand. fMRI was collected while subjects participated in a sustained continuous performance task with low and high attention demands. 162 competing model architectu...

  18. Unfazed or Dazed and Confused: Does Early Adolescent Marijuana Use Cause Sustained Impairments in Attention and Academic Functioning?

    OpenAIRE

    Pardini, Dustin; White, Helene; Xiong, Shuangyan; Bechtold, Jordan; Chung, Tammy; Loeber, Rolf; Hipwell, Alison

    2015-01-01

    There is some suggestion that heavy marijuana use during early adolescence (prior to age 17) may cause significant impairments in attention and academic functioning that remain following sustained periods of abstinence. However, no longitudinal studies have examined whether both male and female adolescents who engage in low (less than once a month) to moderate (at least once a monthly) marijuana use experience increased problems with attention and academic performance, and whether these probl...

  19. Effects of methylphenidate and behavioral contingencies on sustained attention in attention-deficit hyperactivity disorder: a test of the reward dysfunction hypothesis.

    Science.gov (United States)

    Solanto, M V; Wender, E H; Bartell, S S

    1997-01-01

    Psychostimulants and behavior therapy have been postulated to be effective in treating attention-deficit hyperactivity disorder (ADHD) by compensating for a pathologically elevated reward threshold, but no studies have compared reinforcement to psychostimulants in maintaining task performance. The separate and combined effects of methylphenidate (MPH, 0.6 mg/kg) and a behavioral intervention (reward plus response cost) were assessed on a continuous performance test (CPT, a measure of sustained attention) modified to deliver auditory feedback contingent upon the subject's responses. Each of 22 children (6-10 years old) with ADHD were tested under four treatment conditions: placebo + feedback, placebo + behavioral contingencies, MPH + feedback, and MPH + contingencies. CPT performance, indexed by d' (ability to discriminate between target and false targets), was significantly better with MPH than with placebo, showing reduced deterioration over time. Contingency treatment improved mean d' compared to placebo + feedback but, in contrast, had no effect on the slope of performance deterioration. Addition of contingencies to MPH did not yield further improvement. The results indicate that MPH improved sustained attention on a laboratory task (and reduced task-irrelevant and other disinhibited behaviors), whereas behavioral contingencies did not. These findings suggest that, although both interventions improved stimulus discrimination processes, only MPH enhanced processes that mediate the regulation of effort over time. In addition, the disjunction between the effects of reward and of MPH provides evidence that psychostimulant effects on attention are only partially explained by the stimulation of brain centers associated with reward.

  20. The Resource Buffer Theory: Connecting the Dots from Conservation to Sustainability

    Science.gov (United States)

    Peter E. Black

    2006-01-01

    Review of conservation history and scientific developments helps us understand relationships between humans, environment, and sustainability. Applying “conservation” to natural resources and practical resource management occurred early in the Twentieth Century; practical economic definitions of conservation and natural resource followed. Resource surpluses underpin the...

  1. Embodied Niche Construction in the Hominin Lineage: Semiotic Structure and Sustained Attention in Human Embodied Cognition

    Directory of Open Access Journals (Sweden)

    Aaron Jonas Stutz

    2014-08-01

    Full Text Available Human evolution unfolded through a rather distinctive, dynamically constructed ecological niche. The human niche is not only generally terrestrial in habitat, while being flexibly and extensively heterotrophic in food-web connections. It is also defined by semiotically structured and structuring embodied cognitive interfaces, connecting the individual organism with the wider environment. The embodied dimensions of niche-population co-evolution have long involved semiotic system construction, which I hypothesize to be an evolutionarily primitive aspect of learning and higher-level cognitive integration and attention in the great apes and humans alike. A clearly pre-linguistic form of semiotic cognitive structuration is suggested to involve recursively learned and constructed object icons. Higher-level cognitive iconic representation of visually, auditorily, or haptically perceived extrasomatic objects would be learned and evoked through indexical connections to proprioceptive and affective somatic states. Thus, private cognitive signs would be defined, not only by their learned and perceived extrasomatic referents, but also by their associations to iconically represented somatic states. This evolutionary modification of animal associative learning is suggested to be adaptive in ecological niches occupied by long-lived, large-bodied ape species, facilitating memory construction and recall in highly varied foraging and social contexts, while sustaining selective attention during goal-directed behavioral sequences. The embodied niche construction (ENC hypothesis of human evolution posits that in the early hominin lineage, natural selection further modified the ancestral ape semiotic adaptations, favoring the recursive structuration of concise iconic narratives of embodied interaction with the environment.

  2. Bupropion sustained release in adolescents with comorbid attention-deficit/hyperactivity disorder and depression.

    Science.gov (United States)

    Daviss, W B; Bentivoglio, P; Racusin, R; Brown, K M; Bostic, J Q; Wiley, L

    2001-03-01

    To determine whether bupropion sustained release (SR) is effective and well-tolerated in adolescents with comorbid attention-deficit/hyperactivity disorder (ADHD) and depression. Subjects were 24 adolescents (aged 11-16 years old) with ADHD and either major depressive disorder or dysthymic disorder. After a 2-week, single-blind placebo lead-in, subjects were treated for 8+ weeks with bupropion SR at doses flexibly titrated up to 3 mg/kg b.i.d. (mean final doses: 2.2 mg/kg q A.M. and 1.7 mg/kg q P.M.). Outcomes were global improvement in ADHD and depression (clinician-rated), along with changes in depressive symptomatology (parent- and child-rated), ADHD symptomatology (parent- and teacher-rated), and functional impairment (parent-rated). Clinicians rated 14 subjects (58%) responders in both depression and ADHD, 7 (29%) responders in depression only, and 1 (4%) a responder in ADHD only. Compared with post-placebo ratings, final parents' (p depressive symptomatology improved significantly, as did parents' (p depressive disorders. However, randomized, placebo-controlled studies are needed.

  3. Comparing the effects of sustained and transient spatial attention on the orienting towards and the processing of electrical nociceptive stimuli

    NARCIS (Netherlands)

    van der Lubbe, Robert Henricus Johannes; Blom, J.H.G.; de Kleine, Elian; Bohlmeijer, Ernst Thomas

    2017-01-01

    We examined whether sustained vs. transient spatial attention differentially affect the processing of electrical nociceptive stimuli. Cued nociceptive stimuli of a relevant intensity (low or high) on the left or right forearm required a foot pedal press. The cued side varied trial wise in the

  4. The influences of task repetition, napping, time of day, and instruction on the Sustained Attention to Response Task

    NARCIS (Netherlands)

    Schie, M.K.M. van; Alblas, E.E.; Thijs, R.D.; Fronczek, R.; Lammers, G.J.; Dijk, J.G. van

    2014-01-01

    Introduction: The Sustained Attention to Response Task (SART) helps to quantify vigilance impairments. Previous studies, in which five SART sessions on one day were administered, demonstrated worse performance during the first session than during the others. The present study comprises two

  5. Sustained Attention Development during the Toddlerhood to Preschool Period: Associations with Toddlers' Emotion Regulation Strategies and Maternal Behaviour

    Science.gov (United States)

    Graziano, Paulo A.; Calkins, Susan D.; Keane, Susan P.

    2011-01-01

    The current study examined the role of maternal behaviour and toddlers' emotion regulation strategies in the development of children's sustained attention abilities. Participants for this study included 447 children (232 girls) obtained from three different cohorts participating in a larger ongoing longitudinal study. When the children were 2…

  6. Sustained Attention Across the Life Span in a Sample of 10,000: Dissociating Ability and Strategy.

    Science.gov (United States)

    Fortenbaugh, Francesca C; DeGutis, Joseph; Germine, Laura; Wilmer, Jeremy B; Grosso, Mallory; Russo, Kathryn; Esterman, Michael

    2015-09-01

    Normal and abnormal differences in sustained visual attention have long been of interest to scientists, educators, and clinicians. Still lacking, however, is a clear understanding of how sustained visual attention varies across the broad sweep of the human life span. In the present study, we filled this gap in two ways. First, using an unprecedentedly large 10,430-person sample, we modeled age-related differences with substantially greater precision than have prior efforts. Second, using the recently developed gradual-onset continuous performance test (gradCPT), we parsed sustained-attention performance over the life span into its ability and strategy components. We found that after the age of 15 years, the strategy and ability trajectories saliently diverge. Strategy becomes monotonically more conservative with age, whereas ability peaks in the early 40s and is followed by a gradual decline in older adults. These observed life-span trajectories for sustained attention are distinct from results of other life-span studies focusing on fluid and crystallized intelligence. © The Author(s) 2015.

  7. Rethinking College Students' Self-Regulation and Sustained Attention: Does Text Messaging during Class Influence Cognitive Learning?

    Science.gov (United States)

    Wei, Fang-Yi Flora; Wang, Y. Ken; Klausner, Michael

    2012-01-01

    This study investigated whether texting during class influences students' cognitive learning. A theoretical model was proposed to study the relationships among college students' self-regulation, texting during class, sustained attention to classroom learning, and cognitive learning (i.e., grade-oriented academic performance and experience-oriented…

  8. Effective connectivity of ascending and descending frontalthalamic pathways during sustained attention: Complex brain network interactions in adolescence.

    Science.gov (United States)

    Jagtap, Pranav; Diwadkar, Vaibhav A

    2016-07-01

    Frontal-thalamic interactions are crucial for bottom-up gating and top-down control, yet have not been well studied from brain network perspectives. We applied network modeling of fMRI signals [dynamic causal modeling (DCM)] to investigate frontal-thalamic interactions during an attention task with parametrically varying levels of demand. fMRI was collected while subjects participated in a sustained continuous performance task with low and high attention demands. 162 competing model architectures were employed in DCM to evaluate hypotheses on bilateral frontal-thalamic connections and their modulation by attention demand, selected at a second level using Bayesian model selection. The model architecture evinced significant contextual modulation by attention of ascending (thalamus → dPFC) and descending (dPFC → thalamus) pathways. However, modulation of these pathways was asymmetric: while positive modulation of the ascending pathway was comparable across attention demand, modulation of the descending pathway was significantly greater when attention demands were increased. Increased modulation of the (dPFC → thalamus) pathway in response to increased attention demand constitutes novel evidence of attention-related gain in the connectivity of the descending attention pathway. By comparison demand-independent modulation of the ascending (thalamus → dPFC) pathway suggests unbiased thalamic inputs to the cortex in the context of the paradigm. Hum Brain Mapp 37:2557-2570, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  9. Effective connectivity of ascending and descending frontal-thalamic pathways during sustained attention: Complex brain network interactions in adolescence

    Science.gov (United States)

    Jagtap, Pranav; Diwadkar, Vaibhav A.

    2016-01-01

    Frontal-thalamic interactions are crucial for bottom-up gating and top-down control, yet have not been well studied from brain network perspectives. We applied network modeling of fMRI signals (Dynamic Causal Modeling; DCM) to investigate frontal-thalamic interactions during an attention task with parametrically varying levels of demand. fMRI was collected while subjects participated in a sustained continuous performance task with low and high attention demands. 162 competing model architectures were employed in DCM to evaluate hypotheses on bilateral frontal-thalamic connections and their modulation by attention demand, selected at a second level using Bayesian Model Selection. The model architecture evinced significant contextual modulation by attention of ascending (thalamus → dPFC) and descending (dPFC → thalamus) pathways. However, modulation of these pathways was asymmetric: While positive modulation of the ascending pathway was comparable across attention demand, modulation of the descending pathway was significantly greater when attention demands were increased. Increased modulation of the (dPFC → thalamus) pathway in response to increased attention demand constitutes novel evidence of attention-related gain in the connectivity of the descending attention pathway. By comparison demand-independent modulation of the ascending (thalamus → dPFC) pathway suggests unbiased thalamic inputs to the cortex in the context of the paradigm. PMID:27145923

  10. Water Sciences - Connecting the dots to achieve the 2030 Agenda for Sustainable Development

    Science.gov (United States)

    Uhlenbrook, Stefan; Ortigara, Angela; Minelli, Lucilla

    2017-04-01

    Land use change, urbanisation, climate change, demographic development and migration, conflicts and peace, change of diets, industry 4.0, globalisation etc. are among the challenges that water sciences need to address to serve societal needs. Water availability per capita is decreasing, water quality is deteriorating at many places, but water demand is continuously escalating. Business as usual in water science is not up to the related challenges. In fact, business as usual cannot be the answer in all aspects, i.e. also current policy making processes will need to improve and take stock of evidences provided by science in order to better address societal challenges. However, exciting developments have been taking place. The global community agreed on a new and ambitious agenda for development, which aims to be comprehensive and include the participation of all stakeholders in one integrated framework. The 2030 Agenda for Sustainable Development provides a stimulating new era, with unique opportunities to reconcile science, society and policy making. Hydrology and water management - in all its facets including wastewater - play a central role in the Agenda 2030, as it is not only central in Sustainable Development Goal (SDG) 6, but it is fundamental for the realization of other SDGs related to, for instance, poverty reduction, sustainable growth, health, food security, climate change, ecosystems (land and sea), gender equality, etc. Despite the recognition of the critical importance of water in this agenda, the implementation of related policies and use of scientific developments represent a difficult task. Two main challenges remain: (i) the utilization of the knowledge and developments already available, and (ii) the need to overcome current and future knowledge gaps ensuring that scientific results support sustainable development effectively. The UN system will produce a Synthesis Report for SDG 6, which is currently being prepared by a UN-Water Task Force that

  11. The pedunculopontine tegmental nucleus and the nucleus basalis magnocellularis: Do both have a role in sustained attention?

    Directory of Open Access Journals (Sweden)

    Latimer Mary P

    2008-01-01

    Full Text Available Abstract Background It is well established that nucleus basalis magnocellularis (NbM lesions impair performance on tests of sustained attention. Previous work from this laboratory has also demonstrated that pedunculopontine tegmental nucleus (PPTg lesioned rats make more omissions on a test of sustained attention, suggesting that it might also play a role in mediating this function. However, the results of the PPTg study were open to alternative interpretation. We aimed to resolve this by conducting a detailed analysis of the effects of damage to each brain region in the same sustained attention task used in our previous work. Rats were trained in the task before surgery and post-surgical testing examined performance in response to unpredictable light signals of 1500 ms and 4000 ms duration. Data for PPTg lesioned rats were compared to control rats, and rats with 192 IgG saporin infusions centred on the NbM. In addition to operant data, video data of rats' performance during the task were also analysed. Results Both lesion groups omitted trials relative to controls but the effect was milder and transient in NbM rats. The number of omitted trials decreased in all groups when tested using the 4000 ms signal compared to the 1500 ms signal. This confirmed previous findings for PPTg lesioned rats. Detailed analysis revealed that the increase in omissions in PPTg rats was not a consequence of motor impairment. The video data (taken on selected days showed reduced lever orientation in PPTg lesioned rats, coupled with an increase in unconditioned behaviours such as rearing and sniffing. In contrast NbM rats showed evidence of inadequate lever pressing. Conclusion The question addressed here is whether the PPTg and NbM both have a role in sustained attention. Rats bearing lesions of either structure showed deficits in the test used. However, we conclude that the most parsimonious explanation for the deficit observed in PPTg rats is inadequate response

  12. Unfazed or Dazed and Confused: Does Early Adolescent Marijuana Use Cause Sustained Impairments in Attention and Academic Functioning?

    Science.gov (United States)

    Pardini, Dustin; White, Helene R; Xiong, Shuangyan; Bechtold, Jordan; Chung, Tammy; Loeber, Rolf; Hipwell, Alison

    2015-10-01

    There is some suggestion that heavy marijuana use during early adolescence (prior to age 17) may cause significant impairments in attention and academic functioning that remain despite sustained periods of abstinence. However, no longitudinal studies have examined whether both male and female adolescents who engage in low (less than once a month) to moderate (at least once a monthly) marijuana use experience increased problems with attention and academic performance, and whether these problems remain following sustained abstinence. The current study used within-individual change models to control for all potential pre-existing and time-stable confounds when examining this potential causal association in two gender-specific longitudinal samples assessed annually from ages 11 to 16 (Pittsburgh Youth Study N = 479; Pittsburgh Girls Study N = 2296). Analyses also controlled for the potential influence of several pertinent time-varying factors (e.g., other substance use, peer delinquency). Prior to controlling for time-varying confounds, analyses indicated that adolescents tended to experience an increase in parent-reported attention and academic problems, relative to their pre-onset levels, during years when they used marijuana. After controlling for several time-varying confounds, only the association between marijuana use and attention problems in the sample of girls remained statistically significant. There was no evidence indicating that adolescents who used marijuana experienced lingering attention and academic problems, relative to their pre-onset levels, after abstaining from use for at least a year. These results suggest that adolescents who engage in low to moderate marijuana use experience an increase in observable attention and academic problems, but these problems appear to be minimal and are eliminated following sustained abstinence.

  13. Revisiting the co-existence of Attention-Deficit/Hyperactivity Disorder and Chronic Tic Disorder in childhood-The case of colour discrimination, sustained attention and interference control.

    Science.gov (United States)

    Uebel-von Sandersleben, Henrik; Albrecht, Björn; Rothenberger, Aribert; Fillmer-Heise, Anke; Roessner, Veit; Sergeant, Joseph; Tannock, Rosemary; Banaschewski, Tobias

    2017-01-01

    Attention Deficit / Hyperactivity Disorder (ADHD) and Chronic Tic Disorder (CTD) are two common and frequently co-existing disorders, probably following an additive model. But this is not yet clear for the basic sensory function of colour processing sensitive to dopaminergic functioning in the retina and higher cognitive functions like attention and interference control. The latter two reflect important aspects for psychoeducation and behavioural treatment approaches. Colour discrimination using the Farnsworth-Munsell 100-hue Test, sustained attention during the Frankfurt Attention Inventory (FAIR), and interference liability during Colour- and Counting-Stroop-Tests were assessed to further clarify the cognitive profile of the co-existence of ADHD and CTD. Altogether 69 children were classified into four groups: ADHD (N = 14), CTD (N = 20), ADHD+CTD (N = 20) and healthy Controls (N = 15) and compared in cognitive functioning in a 2×2-factorial statistical model. Difficulties with colour discrimination were associated with both ADHD and CTD factors following an additive model, but in ADHD these difficulties tended to be more pronounced on the blue-yellow axis. Attention problems were characteristic for ADHD but not CTD. Interference load was significant in both Colour- and Counting-Stroop-Tests and unrelated to colour discrimination. Compared to Controls, interference load in the Colour-Stroop was higher in pure ADHD and in pure CTD, but not in ADHD+CTD, following a sub-additive model. In contrast, interference load in the Counting-Stroop did not reveal ADHD or CTD effects. The co-existence of ADHD and CTD is characterized by additive as well as sub-additive performance impairments, suggesting that their co-existence may show simple additive characteristics of both disorders or a more complex interaction, depending on demand. The equivocal findings on interference control may indicate limited validity of the Stroop-Paradigm for clinical assessments.

  14. Revisiting the co-existence of Attention-Deficit/Hyperactivity Disorder and Chronic Tic Disorder in childhood—The case of colour discrimination, sustained attention and interference control

    Science.gov (United States)

    Rothenberger, Aribert; Fillmer-Heise, Anke; Roessner, Veit; Sergeant, Joseph; Tannock, Rosemary; Banaschewski, Tobias

    2017-01-01

    Objective Attention Deficit / Hyperactivity Disorder (ADHD) and Chronic Tic Disorder (CTD) are two common and frequently co-existing disorders, probably following an additive model. But this is not yet clear for the basic sensory function of colour processing sensitive to dopaminergic functioning in the retina and higher cognitive functions like attention and interference control. The latter two reflect important aspects for psychoeducation and behavioural treatment approaches. Methods Colour discrimination using the Farnsworth-Munsell 100-hue Test, sustained attention during the Frankfurt Attention Inventory (FAIR), and interference liability during Colour- and Counting-Stroop-Tests were assessed to further clarify the cognitive profile of the co-existence of ADHD and CTD. Altogether 69 children were classified into four groups: ADHD (N = 14), CTD (N = 20), ADHD+CTD (N = 20) and healthy Controls (N = 15) and compared in cognitive functioning in a 2×2-factorial statistical model. Results Difficulties with colour discrimination were associated with both ADHD and CTD factors following an additive model, but in ADHD these difficulties tended to be more pronounced on the blue-yellow axis. Attention problems were characteristic for ADHD but not CTD. Interference load was significant in both Colour- and Counting-Stroop-Tests and unrelated to colour discrimination. Compared to Controls, interference load in the Colour-Stroop was higher in pure ADHD and in pure CTD, but not in ADHD+CTD, following a sub-additive model. In contrast, interference load in the Counting-Stroop did not reveal ADHD or CTD effects. Conclusion The co-existence of ADHD and CTD is characterized by additive as well as sub-additive performance impairments, suggesting that their co-existence may show simple additive characteristics of both disorders or a more complex interaction, depending on demand. The equivocal findings on interference control may indicate limited validity of the Stroop-Paradigm for

  15. Re-examining sustained attention deficits as vulnerability indicators for schizophrenia: stability in the long term course.

    Science.gov (United States)

    Liu, Shi K; Hsieh, Ming-Hsien; Hwang, Tzung J; Hwu, Hai-Gwo; Liao, Shih-Cheng; Lin, Sheng-Hsiang; Chen, Wei J

    2006-10-01

    This study examined the longitudinal patterns in the sustained attention deficits detected by the Continuous Performance Test (CPT) and the factors influencing such changes in consecutively admitted schizophrenia patients (n=224) followed up for 4-7 year. Exploratory growth mixture modeling analyses of subjects' CPT performances over successive follow-ups revealed that three major (accounting for 92.8%) plus one minor subgroups could be delineated. Subgrouping was then performed on a subsample of 104 subjects who had at least 3 times of CPT data. Based on subjects' adjusted z score of the test sensitivity index d' derived from comparing with a community sample, patients were divided into three subgroups: no impairment (-1), moderate impairment (-2.5 to -1), and severe impairment (factors did not. We concluded that there is substantial heterogeneity in schizophrenia patients' long term pattern in sustained attention deficits and those with severe impairment might represent a subgroup with stable vulnerability to schizophrenia.

  16. Sustained attention is associated with right superior longitudinal fasciculus and superior parietal white matter microstructure in children.

    Science.gov (United States)

    Klarborg, Brith; Skak Madsen, Kathrine; Vestergaard, Martin; Skimminge, Arnold; Jernigan, Terry L; Baaré, William F C

    2013-12-01

    Sustained attention develops during childhood and has been linked to the right fronto-parietal cortices in functional imaging studies; however, less is known about its relation to white matter (WM) characteristics. Here we investigated whether the microstructure of the WM underlying and connecting the right fronto-parietal cortices was associated with sustained attention performance in a group of 76 typically developing children aged 7-13 years. Sustained attention was assessed using a rapid visual information processing paradigm. The two behavioral measures of interest were the sensitivity index d' and the coefficient of variation in reaction times (RTCV ). Diffusion-weighted imaging was performed. Mean fractional anisotropy (FA) was extracted from the WM underlying right dorsolateral prefrontal (DLPFC) and parietal cortex (PC), and the right superior longitudinal fasciculus (SLF), as well as equivalent anatomical regions-of-interest (ROIs) in the left hemisphere and mean global WM FA. When analyzed collectively, right hemisphere ROIs FA was significantly associated with d' independently of age. Follow-up analyses revealed that only FA of right SLF and the superior part of the right PC contributed significantly to this association. RTCV was significantly associated with right superior PC FA, but not with right SLF FA. Observed associations remained significant after controlling for FA of equivalent left hemisphere ROIs or global mean FA. In conclusion, better sustained attention performance was associated with higher FA of WM in regions connecting right frontal and parietal cortices. Further studies are needed to clarify to which extent these associations are driven by maturational processes, stable characteristics and/or experience. Copyright © 2012 Wiley Periodicals, Inc.

  17. Low-frequency fluctuation in continuous real-time feedback of finger force: a new paradigm for sustained attention.

    Science.gov (United States)

    Dong, Zhang-Ye; Liu, Dong-Qiang; Wang, Jue; Qing, Zhao; Zang, Zhen-Xiang; Yan, Chao-Gan; Zang, Yu-Feng

    2012-08-01

    Behavioral studies have suggested a low-frequency (0.05 Hz) fluctuation of sustained attention on the basis of the intra-individual variability of reaction-time. Conventional task designs for functional magnetic resonance imaging (fMRI) studies are not appropriate for frequency analysis. The present study aimed to propose a new paradigm, real-time finger force feedback (RT-FFF), to study the brain mechanisms of sustained attention and neurofeedback. We compared the low-frequency fluctuations in both behavioral and fMRI data from 38 healthy adults (19 males; mean age, 22.3 years). Two fMRI sessions, in RT-FFF and sham finger force feedback (S-FFF) states, were acquired (TR 2 s, Siemens Trio 3-Tesla scanner, 8 min each, counter-balanced). Behavioral data of finger force were obtained simultaneously at a sampling rate of 250 Hz. Frequency analysis of the behavioral data showed lower amplitude in the low-frequency band (0.004-0.104 Hz) but higher amplitude in the high-frequency band (27.02-125 Hz) in the RT-FFF than the S-FFF states. The mean finger force was not significantly different between the two states. fMRI data analysis showed higher fractional amplitude of low-frequency fluctuation (fALFF) in the S-FFF than in the RT-FFF state in the visual cortex, but higher fALFF in RT-FFF than S-FFF in the middle frontal gyrus, the superior frontal gyrus, and the default mode network. The behavioral results suggest that the proposed paradigm may provide a new approach to studies of sustained attention. The fMRI results suggest that a distributed network including visual, motor, attentional, and default mode networks may be involved in sustained attention and/or real-time feedback. This paradigm may be helpful for future studies on deficits of attention, such as attention deficit hyperactivity disorder and mild traumatic brain injury.

  18. Sustained attention in skilled and novice martial arts athletes: a study of event-related potentials and current sources.

    Science.gov (United States)

    Sanchez-Lopez, Javier; Silva-Pereyra, Juan; Fernandez, Thalia

    2016-01-01

    Background. Research on sports has revealed that behavioral responses and event-related brain potentials (ERP) are better in expert than in novice athletes for sport-related tasks. Focused attention is essential for optimal athletic performance across different sports but mainly in combat disciplines. During combat, long periods of focused attention (i.e., sustained attention) are required for a good performance. Few investigations have reported effects of expertise on brain electrical activity and its neural generators during sport-unrelated attention tasks. The aim of the present study was to assess the effect of expertise (i.e., skilled and novice martial arts athletes) analyzing the ERP during a sustained attention task (Continuous Performance Task; CPT) and the cortical three-dimensional distribution of current density, using the sLORETA technique. Methods. CPT consisted in an oddball-type paradigm presentation of five stimuli (different pointing arrows) where only one of them (an arrow pointing up right) required a motor response (i.e., target). CPT was administered to skilled and novice martial arts athletes while EEG were recorded. Amplitude ERP data from target and non-target stimuli were compared between groups. Subsequently, current source analysis for each ERP component was performed on each subject. sLORETA images were compared by condition and group using Statistical Non-Parametric Mapping analysis. Results. Skilled athletes showed significant amplitude differences between target and non-target conditions in early ERP components (P100 and P200) as opposed to the novice group; however, skilled athletes showed no significant effect of condition in N200 but novices did show a significant effect. Current source analysis showed greater differences in activations in skilled compared with novice athletes between conditions in the frontal (mainly in the Superior Frontal Gyrus and Medial Frontal Gyrus) and limbic (mainly in the Anterior Cingulate Gyrus) lobes

  19. Sustained attention in skilled and novice martial arts athletes: a study of event-related potentials and current sources

    Directory of Open Access Journals (Sweden)

    Javier Sanchez-Lopez

    2016-01-01

    Full Text Available Background. Research on sports has revealed that behavioral responses and event-related brain potentials (ERP are better in expert than in novice athletes for sport-related tasks. Focused attention is essential for optimal athletic performance across different sports but mainly in combat disciplines. During combat, long periods of focused attention (i.e., sustained attention are required for a good performance. Few investigations have reported effects of expertise on brain electrical activity and its neural generators during sport-unrelated attention tasks. The aim of the present study was to assess the effect of expertise (i.e., skilled and novice martial arts athletes analyzing the ERP during a sustained attention task (Continuous Performance Task; CPT and the cortical three-dimensional distribution of current density, using the sLORETA technique. Methods. CPT consisted in an oddball-type paradigm presentation of five stimuli (different pointing arrows where only one of them (an arrow pointing up right required a motor response (i.e., target. CPT was administered to skilled and novice martial arts athletes while EEG were recorded. Amplitude ERP data from target and non-target stimuli were compared between groups. Subsequently, current source analysis for each ERP component was performed on each subject. sLORETA images were compared by condition and group using Statistical Non-Parametric Mapping analysis. Results. Skilled athletes showed significant amplitude differences between target and non-target conditions in early ERP components (P100 and P200 as opposed to the novice group; however, skilled athletes showed no significant effect of condition in N200 but novices did show a significant effect. Current source analysis showed greater differences in activations in skilled compared with novice athletes between conditions in the frontal (mainly in the Superior Frontal Gyrus and Medial Frontal Gyrus and limbic (mainly in the Anterior Cingulate

  20. Medial prefrontal lesions in mice impair sustained attention but spare maintenance of information in working memory

    Science.gov (United States)

    Kahn, Julia B.; Ward, Ryan D.; Kahn, Lora W.; Rudy, Nicole M.; Kandel, Eric R.; Balsam, Peter D.; Simpson, Eleanor H.

    2012-01-01

    Working memory and attention are complex cognitive functions that are disrupted in several neuropsychiatric disorders. Mouse models of such human diseases are commonly subjected to maze-based tests that can neither distinguish between these cognitive functions nor isolate specific aspects of either function. Here, we have adapted a simple visual discrimination task, and by varying only the timing of events within the same task construct, we are able to measure independently the behavioral response to increasing attentional demand and increasing length of time that information must be maintained in working memory. We determined that mPFC lesions in mice impair attention but not working memory maintenance. PMID:23073640

  1. The alpha-2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD

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    Sagvolden Terje

    2006-12-01

    Full Text Available Abstract Background ADHD is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Overactivity, impulsiveness, and inattentiveness are presently regarded as the main clinical symptoms. There is no biological marker, but there is considerable evidence to suggest that ADHD behavior is associated with poor dopaminergic and noradrenergic modulation of neuronal circuits that involve the frontal lobes. The best validated animal model of ADHD, the Spontaneously Hypertensive Rat (SHR, shows pronounced overactivity, impulsiveness, and deficient sustained attention. While dopamine release is decreased in SHR prefrontal cortex, norepinephrine concentrations are elevated. The noradrenergic system appears to be hyperactive as a result of impaired alpha-2A adrenoceptor regulation. Thus, the present study tested behavioral effects of the centrally acting alpha-2A adrenoceptor agonist guanfacine on SHR behavior. Methods The present study tested behavioral effects of guanfacine at doses of 0.075, 0.15, 0.30 and 0.60 mg base/kg i.p. in both male SHRs and their controls, the Wistar Kyoto rat (WKY. ADHD-like behavior was tested with a visual discrimination task measuring overactivity, impulsiveness and inattentiveness. Results The striking impulsiveness, overactivity, and reduced sustained attention during baseline conditions in the SHR improved by treatment with guanfacine. The most pronounced improvement in SHR behavior was seen following the two highest doses (0.3 and 0.6 mg/kg of guanfacine when SHR behaviors virtually normalized. The positive effects of the drug were most marked towards the end of the session. Conclusion The results indicate that guanfacine improved poor noradrenergic modulation of neuronal circuits that involve the frontal lobes in an animal model of ADHD. The present results support the beneficial effects of guanfacine on ADHD behavior reported clinically and experimentally in primate

  2. Improvements in concentration, working memory and sustained attention following consumption of a natural citicoline-caffeine beverage.

    Science.gov (United States)

    Bruce, Steven E; Werner, Kimberly B; Preston, Brittany F; Baker, Laurie M

    2014-12-01

    This study examined the neurocognitive and electrophysiological effects of a citicoline-caffeine-based beverage in 60 healthy adult participants enrolled in a randomized, double-blind, placebo-controlled trial. Measures of electrical brain activity using electroencephalogram (EEG) and neuropsychological measures examining attention, concentration and reaction time were administered. Compared to placebo, participants receiving the citicoline-caffeine beverage exhibited significantly faster maze learning times and reaction times on a continuous performance test, fewer errors in a go/no-go task and better accuracy on a measure of information processing speed. EEG results examining P450 event-related potentials revealed that participants receiving the citicoline-caffeine beverage exhibited higher P450 amplitudes than controls, suggesting an increase in sustained attention. Overall, these findings suggest that the beverage significantly improved sustained attention, cognitive effort and reaction times in healthy adults. Evidence of improved P450 amplitude indicates a general improvement in the ability to accommodate new and relevant information within working memory and overall enhanced brain activation.

  3. Competitive interactions of attentional resources in early visual cortex during sustained visuospatial attention within or between visual hemifields: evidence for the different-hemifield advantage.

    Science.gov (United States)

    Walter, Sabrina; Quigley, Cliodhna; Mueller, Matthias M

    2014-05-01

    Performing a task across the left and right visual hemifields results in better performance than in a within-hemifield version of the task, termed the different-hemifield advantage. Although recent studies used transient stimuli that were presented with long ISIs, here we used a continuous objective electrophysiological (EEG) measure of competitive interactions for attentional processing resources in early visual cortex, the steady-state visual evoked potential (SSVEP). We frequency-tagged locations in each visual quadrant and at central fixation by flickering light-emitting diodes (LEDs) at different frequencies to elicit distinguishable SSVEPs. Stimuli were presented for several seconds, and participants were cued to attend to two LEDs either in one (Within) or distributed across left and right visual hemifields (Across). In addition, we introduced two reference measures: one for suppressive interactions between the peripheral LEDs by using a task at fixation where attention was withdrawn from the periphery and another estimating the upper bound of SSVEP amplitude by cueing participants to attend to only one of the peripheral LEDs. We found significantly greater SSVEP amplitude modulations in Across compared with Within hemifield conditions. No differences were found between SSVEP amplitudes elicited by the peripheral LEDs when participants attended to the centrally located LEDs compared with when peripheral LEDs had to be ignored in Across and Within trials. Attending to only one LED elicited the same SSVEP amplitude as Across conditions. Although behavioral data displayed a more complex pattern, SSVEP amplitudes were well in line with the predictions of the different-hemifield advantage account during sustained visuospatial attention.

  4. Advances in Graduate Marketing Curriculum: Paying Attention to Ethical, Social, and Sustainability Issues

    Science.gov (United States)

    Weber, James

    2013-01-01

    This research explores the impact of coercive, mimetic, and normative isomorphic pressures on the coverage and offering of courses addressing ethical, social, and sustainability issues (ESSI) in business schools' graduate marketing curricula. Data from the Aspen Institute's Beyond Grey Pinstripes program are analyzed to detect if significant…

  5. Resting-state connectivity of the sustained attention network correlates with disease duration in idiopathic generalized epilepsy.

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    Mona Maneshi

    Full Text Available INTRODUCTION: In idiopathic generalized epilepsy (IGE, a normal electroencephalogram between generalized spike and wave (GSW discharges is believed to reflect normal brain function. However, some studies indicate that even excluding GSW-related errors, IGE patients perform poorly on sustained attention task, the deficit being worse as a function of disease duration. We hypothesized that at least in a subset of structures which are normally involved in sustained attention, resting-state functional connectivity (FC is different in IGE patients compared to controls and that some of the changes are related to disease duration. METHOD: Seeds were selected based on a sustained attention study in controls. Resting-state functional magnetic resonance imaging (fMRI data was obtained from 14 IGE patients and 14 matched controls. After physiological noise removal, the mean time-series of each seed was used as a regressor in a general linear model to detect regions that showed correlation with the seed. In patients, duration factor was defined based on epilepsy duration. Between-group differences weighted by the duration factor were evaluated with mixed-effects model. Correlation was then evaluated in IGE patients between the FC, averaged over each significant cluster, and the duration factor. RESULTS: Eight of 18 seeds showed significant difference in FC across groups. However, only for seeds in the medial superior frontal and precentral gyri and in the medial prefrontal area, average FC taken over significant clusters showed high correlation with the duration factor. These 3 seeds showed changes in FC respectively with the premotor and superior frontal gyrus, the dorsal premotor, and the supplementary motor area plus precentral gyrus. CONCLUSION: Alterations of FC in IGE patients are not limited to the frontal areas. However, as indicated by specificity analysis, patients with long history of disease show changes in FC mainly within the frontal areas.

  6. Impact of layover length on sleep, subjective fatigue levels, and sustained attention of long-haul airline pilots.

    Science.gov (United States)

    Roach, Gregory D; Petrilli, Renée M A; Dawson, Drew; Lamond, Nicole

    2012-06-01

    Long-haul airline pilots often experience elevated levels of fatigue due to extended work hours and circadian misalignment of sleep and wake periods. During long-haul trips, pilots are typically given 1-3 d off between flights (i.e., layover) to recover from, and prepare for, duty. Anecdotally, some pilots prefer long layovers because it maximizes the time available for recovery and preparation, but others prefer short layovers because it minimizes both the length of the trip, and the degree to which the body clock changes from "home time" to the layover time zone. The aim of this study was to examine the impact of layover length on the sleep, subjective fatigue levels, and capacity to sustain attention of long-haul pilots. Participants were 19 male pilots (10 Captains, 9 First Officers) working for an international airline. Data were collected during an 11- or 12-d international trip. The trips involved (i) 4 d at home prior to the trip; (ii) an eastward flight of 13.5 h across seven time zones; (iii) a layover of either 39 h (i.e., short, n = 9) or 62 h (i.e., long, n = 10); (iv) a return westward flight of 14.3 h across seven time zones; and (v) 4 d off at home after the trip. Sleep was recorded using a self-report sleep diary and wrist activity monitor; subjective fatigue level was measured using the Samn-Perelli Fatigue Checklist; and sustained attention was assessed using the psychomotor vigilance task for a personal digital assistant (PalmPVT). Mixed-model regression analyses were used to determine the effects of layover length (short, long) on the amount of sleep that pilots obtained during the trip, and on the pilots' subjective fatigue levels and capacity to sustain attention. There was no main effect of layover length on ground-based sleep or in-flight sleep, but pilots who had a short layover at the midpoint of their trip had higher subjective fatigue levels and poorer sustained attention than pilots who had a long layover. The results of this study

  7. The effect of contralesional limb activation training and sustained attention training for self-care programmes in unilateral spatial neglect.

    Science.gov (United States)

    Wilson, F. Colin; Manly, Tom; Coyle, Donna; Robertson, Ian H.

    2000-01-01

    PURPOSE: To evaluate the effectiveness of two rehabilitation techniques for unilateral spatial neglect, contra-lesional limb activation and sustained attention training, on impaired activities of daily living. METHODS: Two single case, time-series designs incorporating baseline, intervention and post-intervention phases. RESULTS: Significant improvements were observed in both neuropsychological measures and in the independent performance of everyday activities coincident with the start of training. The benefits were well maintained during the post-training period. CONCLUSIONS: The results support the use of the two techniques in achieving functional goals for unilateral neglect patients.

  8. Medial Prefrontal Lesions in Mice Impair Sustained Attention but Spare Maintenance of Information in Working Memory

    Science.gov (United States)

    Kahn, Julia B.; Ward, Ryan D.; Kahn, Lora W.; Rudy, Nicole M.; Kandel, Eric R.; Balsam, Peter D.; Simpson, Eleanor H.

    2012-01-01

    Working memory and attention are complex cognitive functions that are disrupted in several neuropsychiatric disorders. Mouse models of such human diseases are commonly subjected to maze-based tests that can neither distinguish between these cognitive functions nor isolate specific aspects of either function. Here, we have adapted a simple visual…

  9. The power of competition: Effects of social motivation on attention, sustained physical effort, and learning

    OpenAIRE

    Brynne Catherine DiMenichi; Tricomi, Elizabeth M

    2015-01-01

    Competition has often been implicated as a means to improve effort-based learning and attention. Two experiments examined the effects of competition on effort and memory. In Experiment 1, participants completed a physical effort task in which they were rewarded for winning an overall percentage, or for winning a competition they believed was against another player. In Experiment 2, participants completed a memory task in which they were rewarded for remembering an overall percentage of shapes...

  10. Computerized assessment of sustained attention: interactive effects of task demand, noise, and anxiety.

    Science.gov (United States)

    Ballard, J C

    1996-12-01

    In a sample of 163 college undergraduates, the effects of task demand, noise, and anxiety on Continuous Performance Test (CPT) errors were evaluated with multiple regression and multivariate analysis of variance. Results indicated significantly more omission errors on the difficult task. Complex interaction effects of noise and self-reported anxiety yielded more omissions in quiet intermittent white noise, particularly for high-anxious subjects performing the difficult task. Anxiety levels tended to increase from pretest to posttest, particularly for low-anxious subjects in the quiet, difficult-task condition, while a decrease was seen for high-anxious subjects in the loud, easy-task condition. Commission errors were unrelated to any predictor variables, suggesting that "attention" cannot be considered a unitary phenomenon. The variety of direct and interactive effects on vigilance performance underscore the need for clinicians to use a variety of measures to assess attentional skills, to avoid diagnosis of attention deficits on the basis of a single computerized task performance, and to rule out anxiety and other contributors to poor vigilance task performance.

  11. Applicability of the free field Sustained Auditory Attention Ability Test (SAAAT

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    Feniman, Mariza Ribeiro

    2012-01-01

    Full Text Available Introduction: The attention is an underlying neuropsychology function to all the cognitive processes. The auditory deficiency compromises the normal development of the child, modifying diverse auditory abilities, including the attention. Objective: to compare the performance of children in the Test of the Ability of Auditory Attention Support, as for the different forms of application (auricular phones and free field, sort and, application order. Method: 40 children (7 years old voluntary with typical development had participated, divided in two groups: G1 and G2, composites of 20 children each. The application of the THAAS in the G1 if gave first with auricular phones and after that in free field and the G2 the process was inverse. The evaluation consisted in: specific questionnaire, auditory tests and application of the THAAS. Results: It did not have significant difference how much to the sort. For the THAAS with phones, the G1 presented greater amount of errors of carelessness and total punctuation. For the THAAS in field it had a significant difference of the G2 for the monitoring decrease. How much to the application form, the G1 demonstrated a bigger number of errors when it was used phones. The G2 did not demonstrate difference. Conclusion: It had viability in the application of the THAAS in Free Field, being able to be adopted the same used normative values for the conventional way of evaluation.

  12. A comparison between effectiveness of three types of music on memory activity and sustained attention in schizophrenic patients

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    Narges bahmany

    2014-10-01

    Full Text Available Background: schizophrenia is a psychiatric disorder in which a lot of cognitive functions including memory, attention, motor skills, executive functions and intelligence are compromised. Numerous empirical studies showed that schizophrenic patients have problem in sustain retention and memory activity. The objective of this study was a comparison between effectiveness of three types of music on memory activity and sustain retention in schizophrenic patients. Material and Methods: A total of 60 schizophrenic patients (30 males , 30 females 18-48 years old were selected from available sampling frame. Participants were otherwise healthy except for schizophrenia. Wechsler Memory Scale and cognitive diagnostic battery Kay test were taken from all subjects. Then patients were randomly divided into three experimental groups (Iranian classic, western classic and pop music and three control groups. There were 10 participants (5 male, 5 female in each group. After taking these tests, music therapy course was performed on experimental groups. After music therapy sessions were completed, tests were taken again from groups. Results: Covariance analysis results indicated that music therapy is overall effective on memory activity. But type of music had no effect in improving memory activity. There wasn’t significant difference between groups considering type of music. Furthermore, covariance analysis showed that music therapy is totally effective on sustain retention and type of music is effective in this intervention. Pop music had the most effectiveness on schizophrenic patients in improving sustain retention. Conclusion: Performing music therapy improves memory and retention. More over, using pop music particularly has the most effect in improving sustain retention in schizophrenic patients.

  13. Comparing Treatment Effect Measurements in Narcolepsy: The Sustained Attention to Response Task, Epworth Sleepiness Scale and Maintenance of Wakefulness Test.

    Science.gov (United States)

    van der Heide, Astrid; van Schie, Mojca K M; Lammers, Gert Jan; Dauvilliers, Yves; Arnulf, Isabelle; Mayer, Geert; Bassetti, Claudio L; Ding, Claire-Li; Lehert, Philippe; van Dijk, J Gert

    2015-07-01

    To validate the Sustained Attention to Response Task (SART) as a treatment effect measure in narcolepsy, and to compare the SART with the Maintenance of Wakefulness Test (MWT) and the Epworth Sleepiness Scale (ESS). Validation of treatment effect measurements within a randomized controlled trial (RCT). Ninety-five patients with narcolepsy with or without cataplexy. The RCT comprised a double-blind, parallel-group, multicenter trial comparing the effects of 8-w treatments with pitolisant (BF2.649), modafinil, or placebo (NCT01067222). MWT, ESS, and SART were administered at baseline and after an 8-w treatment period. The severity of excessive daytime sleepiness and cataplexy was also assessed using the Clinical Global Impression scale (CGI-C). The SART, MWT, and ESS all had good reliability, obtained for the SART and MWT using two to three sessions in 1 day. The ability to distinguish responders from nonresponders, classified using the CGI-C score, was high for all measures, with a high performance for the SART (r = 0.61) and the ESS (r = 0.54). The Sustained Attention to Response Task is a valid and easy-to-administer measure to assess treatment effects in narcolepsy, enhanced by combining it with the Epworth Sleepiness Scale. © 2015 Associated Professional Sleep Societies, LLC.

  14. Effect of Alpinia galanga on Mental Alertness and Sustained Attention With or Without Caffeine: A Randomized Placebo-Controlled Study.

    Science.gov (United States)

    Srivastava, Shalini; Mennemeier, Mark; Pimple, Surekha

    2017-09-14

    Although Alpinia galanga has been reported to improve cognitive performance in animals, it has not been thoroughly studied for its potential psychostimulant effect in humans. A randomized, double-dummy, double-blind, placebo-controlled cross-over study was conducted to determine the effect of A galanga on mental alertness and sustained attention in comparison with caffeine and placebo in participants with a habitual caffeine intake. Fifty-nine participants (18-40 years and body mass index of ≥18.5 and safety and tolerability, were analyzed by validated methods. In the E-AG-01 group, the alertness score was increased by 11.65 ± 23.94, 12.50 ± 19.73, and 12.62 ± 0.68 ms from baseline at 1, 3 (p = 0.042), and 5 hours, respectively, indicating its efficacy to enhance mental alertness and the increase in alertness score as compared to placebo. In the composite group (E-AG-01 with caffeine), mean response time was significantly reduced, by 15.55 ms (p = 0.026) at 3 hours. A galanga (E-AG-01) induces a beneficial effect in mental alertness and the combination of A galanga with caffeine impedes the caffeine crash and improves sustained attention at 3 hours. Thus, these stimulant effects might yield a new usage for A galanga as a key ingredient in energy drinks or similar products.

  15. The effects of self-control on cognitive resource allocation during sustained attention: a transcranial Doppler investigation.

    Science.gov (United States)

    Becker, Alexandra; Mandell, Arielle R; Tangney, June P; Chrosniak, Linda D; Shaw, Tyler H

    2015-07-01

    Vigilance, or sustained attention, is a required ability in many operational professions. While past research has consistently indicated that vigilance performance declines over time, referred to as the vigilance decrement, the theoretical mechanisms underlying the decrement continue to be explored. In the current study, trait self-control was examined to determine how this individual differences measure may contribute to the theoretical explanation of vigilance decrement. Transcranial Doppler sonography (TCD) was used as a measure of cerebral blood flow velocity (CBFV), as previous research has indicated that CBFV may index attentional resource allocation during vigilance (e.g., Shaw et al. in Hum Factors Ergon Soc 50:1619-1623, 2009). Participants performed a demanding 12-min computer-based vigilance task. Prior to the task, a validated self-report measure was used to determine trait-level self-control, and subjective workload was measured after the task was completed. Participants were divided, based upon survey responses, as either low- or high-trait self-control. Performance results showed a significant decrement across participants, but no significant main effect or interaction relating to the self-control measure was observed. Results relating to the TCD measure showed a significant decline in CBFV in the low self-control group, but no CBFV decrement was observed in the high self-control group. The subjective workload results revealed a nonsignificant trend of the low self-control group becoming more frustrated after the task. These results suggest that there are differences in the resource allocation strategies between low and high self-control participants. How trait self-control can add to an understanding of the theoretical underpinnings of sustained attention performance is discussed.

  16. Sustained engagement of attention is associated with increased negative self-referent processing in major depressive disorder.

    Science.gov (United States)

    Dainer-Best, Justin; Trujillo, Logan T; Schnyer, David M; Beevers, Christopher G

    2017-10-01

    This study investigated the link between self-reference and attentional engagement in adults with (n=22) and without (HC; n=24) Major Depressive Disorder (MDD). Event-related potentials (ERPs) were recorded while participants completed the Self-Referent Encoding Task (SRET). MDD participants endorsed significantly fewer positive words and more negative words as self-descriptive than HC participants. A whole-scalp data analysis technique revealed that the MDD participants had larger difference wave (negative words minus positive words) ERP amplitudes from 380 to 1000ms across posterior sites, which positively correlated with number of negative words endorsed. No group differences were observed for earlier attentional components (P1, P2). The results suggest that among adults with MDD, negative stimuli capture attention during later information processing; this engagement is associated with greater self-referent endorsement of negative adjectives. Sustained cognitive engagement for self-referent negative stimuli may be an important target for neurocognitive depression interventions. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. A Novel Feed-Forward Modeling System Leads to Sustained Improvements in Attention and Academic Performance.

    Science.gov (United States)

    McDermott, Ashley F; Rose, Maya; Norris, Troy; Gordon, Eric

    2016-01-28

    This study tested a novel feed-forward modeling (FFM) system as a nonpharmacological intervention for the treatment of ADHD children and the training of cognitive skills that improve academic performance. This study implemented a randomized, controlled, parallel design comparing this FFM with a nonpharmacological community care intervention. Improvements were measured on parent- and clinician-rated scales of ADHD symptomatology and on academic performance tests completed by the participant. Participants were followed for 3 months after training. Participants in the FFM training group showed significant improvements in ADHD symptomatology and academic performance, while the control group did not. Improvements from FFM were sustained 3 months later. The FFM appeared to be an effective intervention for the treatment of ADHD and improving academic performance. This FFM training intervention shows promise as a first-line treatment for ADHD while improving academic performance. © The Author(s) 2016.

  18. Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task.

    Science.gov (United States)

    Foxe, John J; Morie, Kristen P; Laud, Peter J; Rowson, Matthew J; de Bruin, Eveline A; Kelly, Simon P

    2012-06-01

    Caffeine and L-theanine, both naturally occurring in tea, affect the ability to make rapid phasic deployments of attention to locations in space as reflected in behavioural performance and alpha-band oscillatory brain activity (8-14 Hz). However, surprisingly little is known about how these compounds affect an aspect of attention that has been more popularly associated with tea, namely vigilant attention: the ability to maintain focus on monotonous tasks over protracted time-periods. Twenty-seven participants performed the Sustained Attention to Response Task (SART) over a two-hour session on each of four days, on which they were administered caffeine (50 mg), theanine (100 mg), the combination, or placebo in a double-blind, randomized, cross-over fashion. Concurrently, we recorded oscillatory brain activity through high-density electroencephalography (EEG). We asked whether either compound alone, or both in combination, would affect performance of the task in terms of reduced error rates over time, and whether changes in alpha-band activity would show a relationship to such changes in performance. When treated with placebo, participants showed a rise in error rates, a pattern that is commonly observed with increasing time-on-task, whereas after caffeine and theanine ingestion, error rates were significantly reduced. The combined treatment did not confer any additional benefits over either compound alone, suggesting that the individual compounds may confer maximal benefits at the dosages employed. Alpha-band oscillatory activity was significantly reduced on ingestion of caffeine, particularly in the first hour. This effect was not changed by addition of theanine in the combined treatment. Theanine alone did not affect alpha-band activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Sustained attention is associated with right superior longitudinal fasciculus and superior parietal white matter microstructure in children

    DEFF Research Database (Denmark)

    Klarborg, Brith; Skak Madsen, Kathrine; Vestergaard, Martin

    2013-01-01

    ' and the coefficient of variation in reaction times (RT(CV) ). Diffusion-weighted imaging was performed. Mean fractional anisotropy (FA) was extracted from the WM underlying right dorsolateral prefrontal (DLPFC) and parietal cortex (PC), and the right superior longitudinal fasciculus (SLF), as well as equivalent...... anatomical regions-of-interest (ROIs) in the left hemisphere and mean global WM FA. When analyzed collectively, right hemisphere ROIs FA was significantly associated with d' independently of age. Follow-up analyses revealed that only FA of right SLF and the superior part of the right PC contributed...... significantly to this association. RT(CV) was significantly associated with right superior PC FA, but not with right SLF FA. Observed associations remained significant after controlling for FA of equivalent left hemisphere ROIs or global mean FA. In conclusion, better sustained attention performance...

  20. Sustained attention in mice: expanding the translational utility of the SAT by incorporating the Michigan Controlled Access Response Port (MICARP).

    Science.gov (United States)

    St Peters, Megan; Cherian, Ajeesh Koshy; Bradshaw, Marc; Sarter, Martin

    2011-12-01

    Advances in mouse genetic technology have spurred increasing interest in the development of cognitive tasks for mice. Here, we describe and discuss the modifications necessary to adapt a task for the assessment of sustained attention performance for use in mice, including for taxing the top-down control of such performance. The validity of the Sustained Attention Task (SAT), including the distractor version (dSAT), has previously been demonstrated in rats and humans. This task requires moveable or retractable operanda; insertion of operanda into the operant chambers cues animals to respond to a prior signal or non-signal event, reporting either a hit or a miss, or a correct rejection or false alarm, respectively. Retractable levers did not support sufficiently high and stable levels of performance in mice. Given the widespread use of static nose-poke devices for testing operant performance in mice, we therefore designed and fabricated a retractable nose-poke device. As this device extends into chambers, a hole for nose-poking is slowly opened and closed again as the device retracts (termed the "Michigan Controlled Access Response Port", MICARP). Results describe the effects of variation of signal duration and event rate, trial outcome and trial type probability, effects of mice deprivation levels, and the reliability of SAT and dSAT performance. Mice perform the SAT and dSAT at levels comparable to those observed in rats. This task will be of assistance in expanding the translational usefulness of the SAT and dSAT. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Benefits of Sleep Extension on Sustained Attention and Sleep Pressure Before and During Total Sleep Deprivation and Recovery.

    Science.gov (United States)

    Arnal, Pierrick J; Sauvet, Fabien; Leger, Damien; van Beers, Pascal; Bayon, Virginie; Bougard, Clément; Rabat, Arnaud; Millet, Guillaume Y; Chennaoui, Mounir

    2015-12-01

    To investigate the effects of 6 nights of sleep extension on sustained attention and sleep pressure before and during total sleep deprivation and after a subsequent recovery sleep. Subjects participated in two experimental conditions (randomized cross-over design): extended sleep (EXT, 9.8 ± 0.1 h (mean ± SE) time in bed) and habitual sleep (HAB, 8.2 ± 0.1 h time in bed). In each condition, subjects performed two consecutive phases: (1) 6 nights of either EXT or HAB (2) three days in-laboratory: baseline, total sleep deprivation and after 10 h of recovery sleep. Residential sleep extension and sleep performance laboratory (continuous polysomnographic recording). 14 healthy men (age range: 26-37 years). EXT vs. HAB sleep durations prior to total sleep deprivation. Total sleep time and duration of all sleep stages during the 6 nights were significantly higher in EXT than HAB. EXT improved psychomotor vigilance task performance (PVT, both fewer lapses and faster speed) and reduced sleep pressure as evidenced by longer multiple sleep latencies (MSLT) at baseline compared to HAB. EXT limited PVT lapses and the number of involuntary microsleeps during total sleep deprivation. Differences in PVT lapses and speed and MSLT at baseline were maintained after one night of recovery sleep. Six nights of extended sleep improve sustained attention and reduce sleep pressure. Sleep extension also protects against psychomotor vigilance task lapses and microsleep degradation during total sleep deprivation. These beneficial effects persist after one night of recovery sleep. © 2015 Associated Professional Sleep Societies, LLC.

  2. Executive functions and sustained attention:Comparison between age groups of 19-39 and 40-59 years old

    Directory of Open Access Journals (Sweden)

    Camila Rosa de Oliveira

    Full Text Available ABSTRACT Few studies involving the cognition of middle-aged adults are available in the international literature, particularly investigating the process of cognitive aging, executive components and attention. Objectives: The aim of this study was to investigate whether there are differences in performance on neuropsychological tasks of executive functions and sustained attention between two age groups. Methods: The sample consisted of 87 adults aged from 19 to 59 years old, divided into two groups according to the age variable (younger adults and middle-aged adults. All participants were Brazilian and had no sensory, psychiatric or neurological disorders; subjects also had no history of alcohol abuse, and no self-reported use of illicit drugs or antipsychotics. The neuropsychological instruments administered were the Hayling Test, Trail Making Test, Bells Test and verbal fluency tasks. Results: Groups showed no significant differences in relation to sociodemographic variables, educational level or frequency of reading and writing habits. The younger adult group performed better than the middle-aged group on tasks that involved mainly processing speed, cognitive flexibility and lexical search. Conclusions: These findings serve as a valuable reference for cognitive processing in middle-aged adults, since a large number of comparative studies focus only on the younger and later phases of adulthood. Additional studies are needed to investigate possible interaction between different factors such as age and education.

  3. Deficits in Sustained Attention and Changes in Dopaminergic Protein Levels following Exposure to Proton Radiation Are Related to Basal Dopaminergic Function.

    Directory of Open Access Journals (Sweden)

    Catherine M Davis

    Full Text Available The current report assessed the effects of low-level proton irradiation in inbred adult male Fischer 344 and Lewis rats performing an analog of the human Psychomotor Vigilance Test (PVT, commonly utilized as an object risk assessment tool to quantify fatigue and sustained attention in laboratory, clinical, and operational settings. These strains were used to determine if genetic differences in dopaminergic function would impact radiation-induced deficits in sustained attention. Exposure to head-only proton irradiation (25 or 100 cGy disrupted rPVT performance in a strain-specific manner, with 25 cGy-exposed Fischer 344 rats displaying the most severe deficits in sustained attention (i.e., decreased accuracy and increased premature responding; Lewis rats did not display behavioral deficits following radiation. Fischer 344 rats displayed greater tyrosine hydroxylase and dopamine transporter levels in the frontal cortex compared to the Lewis rats, even though radiation exposure increased both of these proteins in the Lewis rats only. Tyrosine hydroxylase was decreased in the parietal cortex of both rat strains following radiation exposure, regardless of proton dose. Strain-specific cytokine changes were also found in the frontal cortex, with the Lewis rats displaying increased levels of putative neurotrophic cytokines (e.g., CNTF. These data support the hypothesis that basal dopaminergic function impacts the severity of radiation-induced deficits in sustained attention.

  4. Mothers' Depressive Symptoms in Infancy and Children's Adjustment in Grade School: The Role of Children's Sustained Attention and Executive Function

    Science.gov (United States)

    Wang, Yiji; Dix, Theodore

    2017-01-01

    On the basis of longitudinal data across 9 years, this study examined the contribution of sustained attention and executive function to the poor cognitive and socioemotional adjustment of school-age children whose mothers had depressive symptoms during the child's infancy. Mothers (N = 1,364) reported depressive symptoms across their child's…

  5. Aggregated effects of combining daily milk consumption and aerobic exercise on short-term memory and sustained attention among female students.

    Science.gov (United States)

    Leong, In-Tyng; Moghadam, Sedigheh; Hashim, Hairul A

    2015-02-01

    Regular aerobic exercise and milk consumption have been found to have positive effects on certain cognitive functions such as short-term memory and sustained attention. However, aggregated effects of combining these modalities have not been explored. This study examined the combined effects of milk supplementation and aerobic exercise on the short-term memory and sustained attention of female students aged 16 yr. (N = 81). The intervention involved serving of 250 ml of regular milk during school days and/or a 1-hr. aerobic exercise period twice per week for 6 weeks. The Digit Span Test and Digit Vigilance Test were used to measure short-term memory and sustained attention, respectively. The combination group (milk and exercise) and exercise group performed significantly better than did the milk and control groups in terms of short-term memory. No significant interaction or group differences were found for sustained attention. The results suggest benefits of regular exercise for students' short-term memory.

  6. The influences of task repetition, napping, time of day, and instruction on the Sustained Attention to Response Task.

    Science.gov (United States)

    van Schie, Mojca K M; Alblas, Eva E; Thijs, Roland D; Fronczek, Rolf; Lammers, Gert Jan; van Dijk, J Gert

    2014-01-01

    The Sustained Attention to Response Task (SART) helps to quantify vigilance impairments.Previous studies, in which five SART sessions on one day were administered, demonstrated worse performance during the first session than during the others. The present study comprises two experiments to identify a cause of this phenomenon. Experiment 1, counting eighty healthy participants, assessed effects of repetition,napping, and time of day on SART performance through a between-groups design. The SART was performed twice in the morning or twice in the afternoon; half of the participants took a 20-minute nap before the second SART. A strong correlation between error count and reaction time (RT) suggested effects of test instruction. Participants gave equal weight to speed and accuracy in Experiment 1; therefore, results of 20 participants were compared to those of 20 additional participants who were told to prefer accuracy (Experiment 2). The average SART error count in Experiment 1 was 10.1; the median RT was 280 ms. Neither repetition nor napping influenced error count or RT. Time of day did not influence error count, but RT was significantly longer for morning than for afternoon SARTs. The additional participants in Experiment 2 had a 49% lower error count and a 14% higher RT than the participants in Experiment 1. Error counts reduced by 50% from the first to the second session of Experiment 2, irrespective of napping or time of day. Preferring accuracy over speed was associated with a significantly lower error count. The data suggest that a worse performance in the first SART session only occurs when instructing participants to prefer accuracy, which is caused by repetition, not by napping or time of day. We advise that participants are instructed to prefer accuracy over speed when performing the SART and that a full practice session is included.

  7. 'Sustainability does not quite get the attention it deserves': synergies and tensions in the sustainability frames of Australian food policy actors.

    Science.gov (United States)

    Trevena, Helen; Kaldor, Jenny Claire; Downs, Shauna M

    2015-09-01

    The development of food policy is strongly influenced by the understanding and position actors adopt in their 'framing' of sustainability. The Australian Government developed a National Food Plan (2010-2013). In public consultations on the National Food Plan Green Paper, the government sought stakeholders' views on sustainability. The present study examined the way in which the food industry and civil society organizations framed sustainability in their submissions to the Green Paper. Submissions by food industry actors and civil society organizations were analysed using a framing matrix that examined positioning, drivers, underlying principles and policy solutions related to sustainability. Submissions were open coded and subsequently organized based on themes within the framing matrix. Australia. One hundred and twenty-four written submissions (1420 pages). While submissions from industry and civil society organizations often framed sustainability similarly, there were also major differences. Civil society organizations were more likely to make the link between the food supply and population health, while industry was more likely to focus on economic sustainability. Both viewed consumer demand as a driver of sustainability, welcomed the idea of a whole-of-government approach and stressed the need for investment in research and development to improve productivity and sustainable farming practices. The meaning of sustainability shifted throughout the policy process. There are opportunities for creating shared value in food policy, where the health, environment and economic dimensions of sustainability can be compatible. However, despite pockets of optimism there is a need for a shared vision of sustainability if Australia is to have a food policy integrating these dimensions.

  8. The impact of 10-minute activity breaks outside the classroom on male students' on-task behaviour and sustained attention: a randomised crossover design.

    Science.gov (United States)

    Wilson, Andrew N; Olds, Timothy; Lushington, Kurt; Petkov, John; Dollman, James

    2016-04-01

    The aim was to evaluate the impact of a brief activity bout outside the classroom on boys' attention and on-task behaviour in the classroom setting. Fifty-eight boys (mean age 11.2 ± 0.6 years) were recruited from a boys' elementary school in Adelaide, South Australia. Two year 5 and, similarly, two year 6 classes were assigned using a crossover design to either four weeks of a 10 minute Active Lesson Break followed by four weeks of a 10 minute Passive Lesson Break (reading) or visa versa. Attention was quantified using a computerised psychomotor vigilance task, and on-task behaviour by direct observation. Neither the Active Lesson nor the Passive Lesson condition significantly affected sustained attention or on-task behaviour, and there were no significant differences between conditions. There was no impact on participants' sustained attention or on-task behaviour after a short activity break between lessons. Brief activity breaks outside the classroom do not compromise participants' on-task behaviour or attention levels upon returning to the classroom, although improvement in these variables is not seen either. However, the results suggest that active breaks are effective for accruing moderate-to-vigorous physical activity without compromising classroom behaviours. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  9. The Effects of Low to Moderate Alcohol Consumption and Binge Drinking in Early Pregnancy on Selective and Sustained Attention in Five-Year-Old Children

    DEFF Research Database (Denmark)

    Underbjerg, Mette; Kesmodel, Ulrik Schiøler; Landrø, Nils Inge

    2012-01-01

    consumption, age, body mass index (BMI), parity, home environment, postnatal smoking in the home, child's health status, and indicators for hearing and vision impairments. Main outcome measures  TEACh-5 attention scores. Results  There were no significant effects on test performance in children of mothers......Please cite this paper as: Underbjerg M, Kesmodel U, Landrø N, Bakketeig L, Grove J, Wimberley T, Kilburn T, Svaerke C, Thorsen P, Mortensen E. The effects of low to moderate alcohol consumption and binge drinking in early pregnancy on selective and sustained attention in 5-year-old children. BJOG...... 2012;119:1211-1221. Objective  The aim was to examine the effects of low to moderate maternal alcohol consumption and binge drinking in early pregnancy on children's attention at 5 years of age. Design  Prospective follow-up study. Setting  Neuropsychological testing in four Danish cities 2003...

  10. Is the emotional Stroop task a special case of mood induction? Evidence from sustained effects of attention under emotion

    National Research Council Canada - National Science Library

    Ben-Haim, Moshe Shay; Mama, Yaniv; Icht, Michal; Algom, Daniel

    Sustained effects of emotion are well known in everyday experience. Surprisingly, such effects are seldom recorded in laboratory studies of the emotional Stroop task, in which participants name the color of emotion and neutral words...

  11. Sustained Auditory Attention Ability Test (SAAAT) in seven-year-old children with cleft lip and palate

    National Research Council Canada - National Science Library

    Lemos, Isabel Cristina Cavalcanti; Feniman, Mariza Ribeiro

    2010-01-01

    Cleft lip and palate (CLP) is a risk indicator to middle ear alterations, which may damage the development of auditory abilities such as attention that is essential to learn new skills, oral and written communication...

  12. Between-session intra-individual variability in sustained, selective, and integrational non-linguistic attention in aphasia.

    Science.gov (United States)

    Villard, Sarah; Kiran, Swathi

    2015-01-01

    A number of studies have identified impairments in one or more types/aspects of attention processing in patients with aphasia (PWA) relative to healthy controls; person-to-person variability in performance on attention tasks within the PWA group has also been noted. Studies using non-linguistic stimuli have found evidence that attention is impaired in this population even in the absence of language processing demands. An underlying impairment in non-linguistic, or domain-general, attention processing could have implications for the ability of PWA to attend during therapy sessions, which in turn could impact long-term treatment outcomes. With this in mind, this study aimed to systematically examine the effect of task complexity on reaction time (RT) during a non-linguistic attention task, in both PWA and controls. Additional goals were to assess the effect of task complexity on between-session intra-individual variability (BS-IIV) in RT and to examine inter-individual differences in BS-IIV. Eighteen PWA and five age-matched neurologically healthy controls each completed a novel computerized non-linguistic attention task measuring five types of attention on each of four different non-consecutive days. A significant effect of task complexity on both RT and BS-IIV in RT was found for the PWA group, whereas the control group showed a significant effect of task complexity on RT but not on BS-IIV in RT. Finally, in addition to these group-level findings, it was noted that different patients exhibited different patterns of BS-IIV, indicating the existence of inter-individual variability in BS-IIV within the PWA group. Results may have implications for session-to-session fluctuations in attention during language testing and therapy for PWA. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Sustained attention in school-age children with congenital hypothyroidism: Influence of episodes of overtreatment in the first three years of life.

    Science.gov (United States)

    García Morales, L; Rodríguez Arnao, M D; Rodríguez Sánchez, A; Dulín Íñiguez, E; Álvarez González, M A

    2017-11-20

    Children with congenital hypothyroidism (CH) are at risk of developing mild cognitive impairment despite normal overall intellectual performance. These deficits may be caused by disease-related and treatment-related factors. This study explores the impact of abnormal thyroid function during the first 3 years of life on attention performance at school age. We included 49 children diagnosed with CH and receiving treatment for the condition: 14 boys (mean age 9.5±2.8 years) and 35 girls (9.6±2.6 years). The number of episodes of normal, under-, and overtreatment were estimated based on TSH levels during their first 3 years of life (at 12, 18, 24, 30, and 36 months). Children were assessed using a computerised version of a Sustained attention test. General linear models were calculated with the attention index as the dependent variable and sex, aetiology, and number of episodes of normal, under-, and overtreatment as independent variables. Higher numbers of episodes of overtreatment (low TSH level) were associated with poorer attention performance at school age (P=.005, r=-0.45). Children with CH should be monitored closely during the first 3 years of life in order to prevent not only hypothyroidism but also any adverse effects of overtreatment that may affect attentional function at school age. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. Introduction of a retention interval in a sustained attention task in rats: effects of a visual distracter and increasing the inter-trial interval.

    Science.gov (United States)

    Burk, Joshua A

    2004-11-30

    The impact of manipulating explicit attentional demands on working memory has not been well studied in rodents. The present experiment was designed to test the effects of incorporating a retention interval in a two-lever sustained attention task that requires discrimination of visual signals and non-signals and that has previously been shown to yield valid measures of attention in the rat. Upon establishing baseline performance, additional manipulations, including presentation of a visual distracter and increasing the length and variability of the inter-trial interval were conducted. During baseline conditions, accurate detection of signals, but not non-signals, decreased as the retention interval was increased. Presentation of a flashing houselight throughout the session eliminated delay-dependent detection of signals. Increasing the inter-trial interval improved detection of signals and decreased detection of non-signals at the longest retention interval. Finally, increasing the variability of the inter-trial interval did not have significant effects on performance above and beyond the effects of increasing the inter-trial interval. The present experiment demonstrates that manipulation of explicit attentional demands can alter working memory performance in the rat. This task may be employed to understand the neuropharmacological and neuroanatomical substrates mediating memory while attentional load is systematically varied.

  15. Differences in Visuo-Motor Control in Skilled vs. Novice Martial Arts Athletes during Sustained and Transient Attention Tasks: A Motor-Related Cortical Potential Study

    Science.gov (United States)

    Sanchez-Lopez, Javier; Fernandez, Thalia; Silva-Pereyra, Juan; Martinez Mesa, Juan A.; Di Russo, Francesco

    2014-01-01

    Cognitive and motor processes are essential for optimal athletic performance. Individuals trained in different skills and sports may have specialized cognitive abilities and motor strategies related to the characteristics of the activity and the effects of training and expertise. Most studies have investigated differences in motor-related cortical potential (MRCP) during self-paced tasks in athletes but not in stimulus-related tasks. The aim of the present study was to identify the differences in performance and MRCP between skilled and novice martial arts athletes during two different types of tasks: a sustained attention task and a transient attention task. Behavioral and electrophysiological data from twenty-two martial arts athletes were obtained while they performed a continuous performance task (CPT) to measure sustained attention and a cued continuous performance task (c-CPT) to measure transient attention. MRCP components were analyzed and compared between groups. Electrophysiological data in the CPT task indicated larger prefrontal positive activity and greater posterior negativity distribution prior to a motor response in the skilled athletes, while novices showed a significantly larger response-related P3 after a motor response in centro-parietal areas. A different effect occurred in the c-CPT task in which the novice athletes showed strong prefrontal positive activity before a motor response and a large response-related P3, while in skilled athletes, the prefrontal activity was absent. We propose that during the CPT, skilled athletes were able to allocate two different but related processes simultaneously according to CPT demand, which requires controlled attention and controlled motor responses. On the other hand, in the c-CPT, skilled athletes showed better cue facilitation, which permitted a major economy of resources and “automatic” or less controlled responses to relevant stimuli. In conclusion, the present data suggest that motor expertise

  16. Differences in visuo-motor control in skilled vs. novice martial arts athletes during sustained and transient attention tasks: a motor-related cortical potential study.

    Directory of Open Access Journals (Sweden)

    Javier Sanchez-Lopez

    Full Text Available Cognitive and motor processes are essential for optimal athletic performance. Individuals trained in different skills and sports may have specialized cognitive abilities and motor strategies related to the characteristics of the activity and the effects of training and expertise. Most studies have investigated differences in motor-related cortical potential (MRCP during self-paced tasks in athletes but not in stimulus-related tasks. The aim of the present study was to identify the differences in performance and MRCP between skilled and novice martial arts athletes during two different types of tasks: a sustained attention task and a transient attention task. Behavioral and electrophysiological data from twenty-two martial arts athletes were obtained while they performed a continuous performance task (CPT to measure sustained attention and a cued continuous performance task (c-CPT to measure transient attention. MRCP components were analyzed and compared between groups. Electrophysiological data in the CPT task indicated larger prefrontal positive activity and greater posterior negativity distribution prior to a motor response in the skilled athletes, while novices showed a significantly larger response-related P3 after a motor response in centro-parietal areas. A different effect occurred in the c-CPT task in which the novice athletes showed strong prefrontal positive activity before a motor response and a large response-related P3, while in skilled athletes, the prefrontal activity was absent. We propose that during the CPT, skilled athletes were able to allocate two different but related processes simultaneously according to CPT demand, which requires controlled attention and controlled motor responses. On the other hand, in the c-CPT, skilled athletes showed better cue facilitation, which permitted a major economy of resources and "automatic" or less controlled responses to relevant stimuli. In conclusion, the present data suggest that motor

  17. Differences in visuo-motor control in skilled vs. novice martial arts athletes during sustained and transient attention tasks: a motor-related cortical potential study.

    Science.gov (United States)

    Sanchez-Lopez, Javier; Fernandez, Thalia; Silva-Pereyra, Juan; Martinez Mesa, Juan A; Di Russo, Francesco

    2014-01-01

    Cognitive and motor processes are essential for optimal athletic performance. Individuals trained in different skills and sports may have specialized cognitive abilities and motor strategies related to the characteristics of the activity and the effects of training and expertise. Most studies have investigated differences in motor-related cortical potential (MRCP) during self-paced tasks in athletes but not in stimulus-related tasks. The aim of the present study was to identify the differences in performance and MRCP between skilled and novice martial arts athletes during two different types of tasks: a sustained attention task and a transient attention task. Behavioral and electrophysiological data from twenty-two martial arts athletes were obtained while they performed a continuous performance task (CPT) to measure sustained attention and a cued continuous performance task (c-CPT) to measure transient attention. MRCP components were analyzed and compared between groups. Electrophysiological data in the CPT task indicated larger prefrontal positive activity and greater posterior negativity distribution prior to a motor response in the skilled athletes, while novices showed a significantly larger response-related P3 after a motor response in centro-parietal areas. A different effect occurred in the c-CPT task in which the novice athletes showed strong prefrontal positive activity before a motor response and a large response-related P3, while in skilled athletes, the prefrontal activity was absent. We propose that during the CPT, skilled athletes were able to allocate two different but related processes simultaneously according to CPT demand, which requires controlled attention and controlled motor responses. On the other hand, in the c-CPT, skilled athletes showed better cue facilitation, which permitted a major economy of resources and "automatic" or less controlled responses to relevant stimuli. In conclusion, the present data suggest that motor expertise

  18. Is the emotional Stroop task a special case of mood induction? Evidence from sustained effects of attention under emotion.

    Science.gov (United States)

    Ben-Haim, Moshe Shay; Mama, Yaniv; Icht, Michal; Algom, Daniel

    2014-01-01

    Sustained effects of emotion are well known in everyday experience. Surprisingly, such effects are seldom recorded in laboratory studies of the emotional Stroop task, in which participants name the color of emotion and neutral words. Color performance is more sluggish with emotion words than with neutral words, the emotional Stroop effect (ESE). The ESE is not sensitive to the order in which the two groups of words are presented, so the effect of exposure to emotion words does not extend to disrupting performance in a subsequent block with neutral words. We attribute this absence of a sustained effect to habituation engendered by excessive repetition of the experimental stimuli. In a series of four experiments, we showed that sustained effects do occur when habituation is removed, and we also showed that the massive exposure to negative stimuli within the ESE paradigm induces a commensurately negative mood. A novel perspective is offered, in which the ESE is considered a special case of mood induction.

  19. Improvements in Concentration, Working Memory, and Sustained Attention Following Consumption of a Natural Citicoline-Caffeine Beverage

    OpenAIRE

    Bruce, Steven E.; Werner, Kimberly B.; Preston, Brittany F.; Baker, Laurie M.

    2014-01-01

    The present study examined the neurocognitive and electrophysiological effects of a citicoline-caffeine-based beverage in 60 healthy adult participants enrolled in a randomized, double-blind, placebo-controlled trial. Measures of electrical brain activity using electroencephalogram (EEG) and neuropsychological measures examining attention, concentration, and reaction time were administered. Compared to placebo, participants receiving the citicoline-caffeine beverage exhibited significantly fa...

  20. Depression-related difficulties disengaging from negative faces are associated with sustained attention to negative feedback during social evaluation and predict stress recovery.

    Science.gov (United States)

    Sanchez, Alvaro; Romero, Nuria; De Raedt, Rudi

    2017-01-01

    The present study aimed to clarify: 1) the presence of depression-related attention bias related to a social stressor, 2) its association with depression-related attention biases as measured under standard conditions, and 3) their association with impaired stress recovery in depression. A sample of 39 participants reporting a broad range of depression levels completed a standard eye-tracking paradigm in which they had to engage/disengage their gaze with/from emotional faces. Participants then underwent a stress induction (i.e., giving a speech), in which their eye movements to false emotional feedback were measured, and stress reactivity and recovery were assessed. Depression level was associated with longer times to engage/disengage attention with/from negative faces under standard conditions and with sustained attention to negative feedback during the speech. These depression-related biases were associated and mediated the association between depression level and self-reported stress recovery, predicting lower recovery from stress after giving the speech.

  1. Dysfunction and dysconnection in cortical-striatal networks during sustained attention: Genetic risk for schizophrenia or bipolar disorder and its impact on brain network function

    Directory of Open Access Journals (Sweden)

    Vaibhav A. Diwadkar

    2014-05-01

    Full Text Available Abnormalities in the brain’s attention network may represent early identifiable neurobiological impairments in individuals at increased risk for schizophrenia or bipolar disorder. Here we provide evidence of dysfunctional regional and network function in adolescents at higher genetic risk for schizophrenia or bipolar disorder (henceforth HGR. During fMRI, participants engaged in a sustained attention task with variable demands. The task alternated between attention (120 s, visual control (passive viewing; 120 s and rest (20 s epochs. Low and high demand attention conditions were created using the rapid presentation of 2- or 3-digit numbers. Subjects were required to detect repeated presentation of numbers. We demonstrate that the recruitment of cortical and striatal regions are disordered in HGR: Relative to typical controls (TC, HGR showed lower recruitment of the dorsal prefrontal cortex, but higher recruitment of the superior parietal cortex. This imbalance was more dramatic in the basal ganglia. There, a group by task demand interaction was observed, such that increased attention demand led to increased engagement in TC, but disengagement in HGR. These activation studies were complemented by network analyses using Dynamic Causal Modeling. Competing model architectures were assessed across a network of cortical-striatal regions, distinguished at a second level using random effects Bayesian model selection. In the winning architecture, HGR were characterized by significant reductions in coupling across both frontal-striatal and frontal-parietal pathways. The effective connectivity analyses indicate emergent network dysconnection, consistent with findings in patients with schizophrenia. Emergent patterns of regional dysfunction and disconnection in cortical-striatal pathways may provide functional biological signatures in the adolescent risk state for psychiatric illness.

  2. Attention processes in autism

    National Research Council Canada - National Science Library

    Martos-Pérez, J

    2008-01-01

    ... findings that have been obtained so far are also reported. Some attentional processes, such as selective or sustained attention, are not altered in autism or not enough evidence has been found to support such a hypothesis...

  3. Mind-wandering in younger and older adults: converging evidence from the Sustained Attention to Response Task and reading for comprehension.

    Science.gov (United States)

    Jackson, Jonathan D; Balota, David A

    2012-03-01

    One mechanism that has been hypothesized to contribute to older adults' changes in cognitive performance is goal neglect or impairment in maintaining task set across time. Mind-wandering and task-unrelated thought may underlie these potential age-related changes. The present study investigated age-related changes in mind-wandering in three different versions of the Sustained Attention to Response Task (SART), along with self-reported mind-wandering during a reading for comprehension task. In the SART, both younger and older adults produced similar levels of faster reaction times before No-Go errors of commission, whereas, older adults produced disproportionate post-error slowing. Subjective self-reports of mind-wandering recorded during the SART and the reading task indicated that older adults were less likely to report mind-wandering than younger adults. Discussion focuses on cognitive and motivational mechanisms that may account for older adults' relatively low levels of reported mind-wandering.

  4. Dot probe performance in two specific phobias.

    Science.gov (United States)

    Wenzel, A; Holt, C S

    1999-11-01

    The present study applied MacLeod, Mathews & Tata's (1986) dot probe attentional deployment methodology to individuals with specific phobias. Attentional deployment towards spider-related, blood-related, positive, negative, and neutral words was examined. Individuals with either spider phobia (N = 13) or blood/injury phobia (N = 14) and non-anxious controls (N = 14) completed the dot probe attentional deployment task. Individuals with specific phobias did not demonstrate an attentional bias towards phobia-related stimuli relevant to their particular fears. Semantic-based information processing paradigms may not be sufficiently potent to demonstrate biased performance towards threatening stimuli in individuals with mild specific phobias who are otherwise healthy.

  5. Partnership for Sustainable Communities - Grants Map -

    Data.gov (United States)

    Department of Transportation — The Partnership for Sustainable Communities is comprised of the Department of Housing and Urban Development (HUD), the US Department of Transportation (DOT), and the...

  6. DOT's CAFE rulemaking analysis.

    Science.gov (United States)

    2013-02-13

    Presentation discusses what DOT needs to consider in setting CAFE standards. How DOT's use of the CAFE Compliance and Effects Modeling System helps to analyze potential CAFE Standards. How DOT might approach the next round of CAFE standards for model...

  7. Mind-wandering in Younger and Older Adults: Converging Evidence from the Sustained Attention to Response Task and Reading for Comprehension

    Science.gov (United States)

    Jackson, Jonathan D.; Balota, David A.

    2011-01-01

    One mechanism that has been hypothesized to contribute to older adults’ changes in cognitive performance is goal neglect or impairment in maintaining task set across time. Mind-wandering and task-unrelated thought may underlie these potential age-related changes. The present study investigated age-related changes in mind-wandering in three different versions of the Sustained Attention to Response task (SART), along with self-reported mind-wandering during a reading for comprehension task. In the SART, both younger and older adults produced similar levels of faster reaction times before No-Go errors of commission, whereas, older adults produced disproportionate post-error slowing. Subjective self-reports of mind-wandering recorded during the SART and the reading task indicated that older adults were less likely to report mind-wandering than younger adults. Discussion focuses on cognitive and motivational mechanisms that may account for older adults’ relatively low levels of reported mind-wandering. PMID:21707183

  8. The use of music with young children to improve sustained attention during a vigilance task in the presence of auditory distractions.

    Science.gov (United States)

    Wolfe, David E; Noguchi, Laura K

    2009-01-01

    The purpose of this study was to examine the use of music to sustain attention of young children during conditions of auditory distractions. Kindergarten students (N=76) were randomly assigned to one of four conditions/groups: (a) spoken story with no distraction, (b) spoken story with distraction, (c) musical story with no distraction, musical story with distraction. Participants were asked to listen to the story and to identify specific "actions" and "animals" that were presented (i.e., spoken or sung) within the story. A tally of correct responses (child pointed to correct actions/animals at appropriate times) was recorded during the listening task. Observations of participants' behaviors while listening were also made by the experimenter using narrative recording procedures. A one-way ANOVA was computed to assess the difference in mean scores across the four experimental conditions. Significant results were found. Further analysis employing a Tukey post hoc/multiple comparisons test revealed significant differences between the spoken story with distraction condition and the musical story with distraction condition. These statistical results, along with the observations of listening behaviors, were discussed in terms of providing suggestions for future research and in lending support to the use of music with young children to improve vigilance within educational and clinical settings.

  9. No-Onset Looming Motion Guides Spatial Attention

    Science.gov (United States)

    von Muhlenen, Adrian; Lleras, Alejandro

    2007-01-01

    These 6 experiments explored the ability of moving random dot patterns to attract attention, as measured by a simple probe-detection task. Each trial began with random motion (i.e., dots linearly moved in random directions). After 1 s motion in 1 hemifield became gradually coherent (i.e., all dots moved up-, down-, left-, or rightwards, or either…

  10. Dot gain compensation in the blue noise mask

    Science.gov (United States)

    Yao, Meng; Parker, Kevin J.

    1995-04-01

    Frequency modulated (FM) halftoning or 'stochastic screening,' has attracted a great deal of attention in the printing industry in recent years. It has several advantages over conventional halftoning. But one serious problem that arises in FM halftoning is dot gain. One approach to stochastic screening uses a specially constructed halftone screen, the blue noise mask (BNM), to produce an unstructured and visually appealing pattern of halftone dots at any gray level. In this paper, we will present methods to correct dot gain with the BNM. Dot gain is related to the area-to-perimeter ration of printed spots. We can exploit this feature in different ways. At a medium level, a B>NM pattern will have 'connected' as well as 'isolated' dots. Normally, as we build down BNM patterns to lower levels, a specific number of white dots will be replace by black dots. Since connected white dots are more likely to be picked than isolated white dots, this will results in substantial dot gain because of the increasing number of isolated white dots. We show that it is possible to constrain the process of constructing a BNM such that isolated dots are preferentially removes, thus significantly reducing dot gain in a BNM.

  11. Attention to Attention

    DEFF Research Database (Denmark)

    Tække, Jesper; Paulsen, Michael Eric

    In these years digital media and wireless networks are introduced in upper secondary schools in Denmark. This implies new “attentional objects” like updates on Facebook or tweets on Twitter within instant reach of the pupils and teachers. Also it implies new kinds of attention (awareness) like when...... this interpretation theoretically through systems theory and medium theory. Further we present initial results from the action research project Socio Media Education (SME) in which we work with how teachers and pupils can handle the new attention-demanding situation, so the new media do not mean spoiled teaching...

  12. Training attentional control in infancy

    National Research Council Canada - National Science Library

    Wass, Sam; Porayska-Pomsta, Kaska; Johnson, Mark H

    2011-01-01

    .... Relative to an active control group, and following only a relatively short training period, posttraining assessments revealed improvements in cognitive control and sustained attention, reduced...

  13. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    1999-01-01

    Semiconductor quantum dots ("solid state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra.Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dots states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  14. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    Semiconductor quantum dots ("solid-state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra. Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dot states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  15. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    and Middleton, 1995). A reminiscence conversation is a dynamic talk-in-interaction, which can produce valuable learning experience for the participants involved. Reminiscence talk contains rich, personal, historic data that can reveal and inform family members of an unknown past. In this seminar/chapter, we......Reminiscence is a self-reflecting process on past events and experiences. Not only does it enable past experiences to be brought to light through talk, but it also creates an affective environment, which allows participants to explore and construct a representation of the self (Buchanan...... of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...

  16. Atención sostenida en niños en edad escolar con hipotiroidismo congénito Sustained attention in school aged children with congenital hypothyroidism

    Directory of Open Access Journals (Sweden)

    Ana Olivares Torres

    2004-08-01

    .0 computerized battery (system for evaluation and follow-up of hypothyroid patients for the detection of disorders in children with congenital hypothyropidism (CH. Three groups of children were studied: learning disorders (LD, congenital hypothyroidism (CG and sound controls (SC. The results show that the values of the children from group CH are at an intermediate level between the SC and the LD, which is interpreted as the existance of a subclinical deficit in sustained attention. The discriminatory capacity of the software used allows its inmediate incorporation to the clinical practice of the national CH early diagnosis program as a very useful complementary tool.

  17. Synthesis of Cesium Lead Halide Perovskite Quantum Dots

    Science.gov (United States)

    Shekhirev, Mikhail; Goza, John; Teeter, Jacob D.; Lipatov, Alexey; Sinitskii, Alexander

    2017-01-01

    Synthesis of quantum dots is a valuable experiment for demonstration and discussion of quantum phenomena in undergraduate chemistry curricula. Recently, a new class of all-inorganic perovskite quantum dots (QDs) with a formula of CsPbX[subscript 3] (X = Cl, Br, I) was presented and attracted tremendous attention. Here we adapt the synthesis of…

  18. Room-temperature dephasing in InAs/GaAs quantum dots

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Hvam, Jørn Märcher

    1999-01-01

    Summary form only given. Semiconductor quantum dots (QDs) are receiving increasing attention for fundamental studies on zero-dimensional confinement and for device applications. Quantum-dot lasers are expected to show superior performances, like high material gain, low and temperature...... stacked layers of InAs-InGaAs-GaAs quantum dots....

  19. Glowing graphene quantum dots and carbon dots: properties, syntheses, and biological applications.

    Science.gov (United States)

    Zheng, Xin Ting; Ananthanarayanan, Arundithi; Luo, Kathy Qian; Chen, Peng

    2015-04-08

    The emerging graphene quantum dots (GQDs) and carbon dots (C-dots) have gained tremendous attention for their enormous potentials for biomedical applications, owing to their unique and tunable photoluminescence properties, exceptional physicochemical properties, high photostability, biocompatibility, and small size. This article aims to update the latest results in this rapidly evolving field and to provide critical insights to inspire more exciting developments. We comparatively review the properties and synthesis methods of these carbon nanodots and place emphasis on their biological (both fundamental and theranostic) applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A habilidade de atenção auditiva sustentada em crianças com fissura labiopalatina e transtorno fonológico Sustained auditory attention ability in children with cleft lip and palate and phonological disorders

    Directory of Open Access Journals (Sweden)

    Tâmyne Ferreira Duarte de Moraes

    2011-12-01

    Full Text Available OBJETIVO: Verificar a habilidade de atenção auditiva sustentada em crianças com fissura labiopalatina e transtorno fonológico, comparando o desempenho com crianças com fissura labiopalatina e ausência de transtorno fonológico. MÉTODOS: Dezessete crianças com idade entre 6 e 11 anos, com fissura labiopalatina transforame unilateral operada e ausência de queixa e/ou alteração auditiva, separadas em dois grupos: GI (com transtorno fonológico e GII (com auŝencia de transtorno fonológico. Para detecção de alteração auditiva foram realizadas audiometria e timpanometria. Para avaliação fonológica foram utilizados os seguintes instrumentos: Teste de Linguagem Infantil e Consciência Fonológica: Instrumento de Avaliação Sequencial. Para avaliar a habilidade de atenção auditiva foi aplicado o Teste da Habilidade de Atenção Auditiva Sustentada. RESULTADOS: Das sete crianças com transtorno fonológico (41%, duas (29% apresentaram alteração nos resultados do Teste da Habilidade de Atenção Auditiva Sustentada. Não houve diferença entre as crianças com fissura labiopalatina e transtorno fonológico e as crianças com fissura labiopalatina e ausência de transtorno fonológico quanto aos resultados do Teste de Habilidade de Atenção Auditiva Sustentada. CONCLUSÃO: A habilidade de atenção auditiva sustentada nas crianças com fissura labiopalatina e transtorno fonológico não difere da habilidade de atenção auditiva sustentada de crianças com fissura labiopalatina sem transtorno fonológico.PURPOSE: To verify the ability of sustained auditory attention in children with cleft lip and palate and phonological disorder, in comparison with the performance of children with cleft lip and palate and absence of phonological disorder. METHODS: Seventeen children with ages between 6 and 11 years, with repaired unilateral complete cleft lip and palate and absence of auditory complaints or hearing problems, were divided into two

  1. Predicting N2pc from anticipatory HbO activity during sustained visuospatial attention: a concurrent fNIRS-ERP study.

    Science.gov (United States)

    Huang, Jing; Wang, Fang; Ding, Yulong; Niu, Haijing; Tian, Fenghua; Liu, Hanli; Song, Yan

    2015-06-01

    Understanding the properties of attentional control, along with the neural mechanisms subserving them, has long invited intense scrutiny in research groups. However, it has not been demonstrated how the top-down anticipatory hemodynamic activation influences the subsequent attentional processing of targets and distractors. Here, with concurrent fNIRS-ERP recording, we explored the potential contribution of anticipatory oxygenated hemoglobin (HbO) based brain activity to attentional control by examining how HbO influences the subsequent ERP N2pc components assumed to reflect attentional selection. We found that expecting a target led to a larger increase of preparatory HbO response over the visual cortex contralateral to the upcoming target, which was positively correlated with the subsequent target-evoked N2pc amplitude. Further, anticipation concerning the presence of a competing distractor resulted in large and prolonged preparatory HbO signals in the visual cortex contralateral to the distractor, indicating that the salient distractor might be actively suppressed by preparatory top-down attentional control. However, the pre-suppressed distractor still captured part of the attention in the subsequent visual search as revealed by a decrease in the N2pc amplitude, and such a distraction effect on N2pc was negatively correlated with preparatory HbO enhancement contralateral to the anticipated distractor. Overall, each individuals attentional shift to the target and resistance to the distractor measured by ERP is predictable in advance via anticipatory hemodynamic activity in the visual cortex measured by fNIRS. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. The effects of low to moderate alcohol consumption and binge drinking in early pregnancy on selective and sustained attention in 5-year-old children.

    Science.gov (United States)

    Underbjerg, M; Kesmodel, U S; Landrø, N I; Bakketeig, L; Grove, J; Wimberley, T; Kilburn, T R; Sværke, C; Thorsen, P; Mortensen, E L

    2012-09-01

    The aim was to examine the effects of low to moderate maternal alcohol consumption and binge drinking in early pregnancy on children's attention at 5 years of age. Prospective follow-up study. Neuropsychological testing in four Danish cities 2003-2008. A cohort of 1628 women and their children sampled from the Danish National Birth Cohort. Participants were sampled based on maternal alcohol consumption during pregnancy. At 5 years of age, the children were tested with the recently developed Test of Everyday Attention for Children at Five (TEACh-5). Parental education, maternal IQ, maternal smoking in pregnancy, the child's age at testing, gender, and tester were considered core confounding factors, whereas the full model also controlled the following potential confounding factors: maternal binge drinking or low to moderate alcohol consumption, age, body mass index (BMI), parity, home environment, postnatal smoking in the home, child's health status, and indicators for hearing and vision impairments. TEACh-5 attention scores. There were no significant effects on test performance in children of mothers drinking up to 8 drinks per week compared with children of mothers who abstained, but there was a significant association between maternal consumption of 9 or more drinks per week and risk of a low overall attention score (OR 3.50, 95% CI 1.15-10.68). No consistent or significant associations were observed between binge drinking and attention test scores. The findings suggest an effect of maternal consumption of 9 or more drinks per week on attention functions in children, but the study detected no effects of lower levels of maternal consumption and no consistent effects of maternal binge drinking. © 2012 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2012 RCOG.

  3. Short-term effects of black pepper (Piper nigrum) and rosemary (Rosmarinus officinalis and Rosmarinus eriocalyx) on sustained attention and on energy and fatigue mood states in young adults with low energy.

    Science.gov (United States)

    Lindheimer, Jacob B; Loy, Bryan D; O'Connor, Patrick J

    2013-08-01

    The purpose was to test whether a single dose of black pepper or rosemary produced short-term enhancements in sustained attention, motivation to perform cognitive tasks, or feelings of mental energy and fatigue. Outcomes were measured in 40 young adults with below average feelings of energy before and twice after they orally consumed capsules containing either black pepper (2.0 g), rosemary (1.7 g), or a placebo (3.1 g rice flour). Sustained attention was measured using a 16-min dual task, in which, single-digit numbers were presented every second on a screen and the participant performed both a primary task [detection of three successive, different odd digits] and a secondary task [detection of the number 6]. Feelings of energy and fatigue were measured using the vigor and fatigue subscales of the Profile of Mood States and visual analog scales (VAS). Analysis of variance showed nonsignificant condition (spice versus placebo)×time (T1, T2, & T3) effects for motivation, measured with a VAS, and the intensity of energy and fatigue feelings. Unadjusted effect sizes revealed that rosemary induced small, transient reductions in false alarm errors (d=0.21) and mental fatigue (d=0.40) at isolated time periods. Time-varying analysis of covariance, controlling for motivation to perform cognitive tasks, showed no significant effects on the primary or secondary task outcomes of correct responses (hits), errors (false alarms, misses), speed of response (reaction time), and signal detection sensitivity. It is concluded that black pepper and rosemary, consumed in a capsule form, in the doses used and while wearing a nose clip to block olfactory effects, do not induce consistent short-term improvements in sustained attention, motivation to perform cognitive tasks, or feelings of mental energy and fatigue in young adults with low energy.

  4. One-step, green, and economic synthesis of water-soluble photoluminescent carbon dots by hydrothermal treatment of wheat straw, and their bio-applications in labeling, imaging, and sensing

    Science.gov (United States)

    Yuan, Ming; Zhong, Ruibo; Gao, Haiyang; Li, Wanrong; Yun, Xiaoling; Liu, Jingran; Zhao, Xinmin; Zhao, Guofen; Zhang, Feng

    2015-11-01

    The use of biomass as renewable and sustainable energy source has attracted the attention of politics and research and development (R&D) facilities around the world. Agricultural straw acts as a typical biowaste, which still needs highly effective recycling to save the biomass urgently at present. Photoluminescent carbon dots (C-dots) are novel biocompatible nanomaterials that have been proved to be produced from many carbon-abundant materials and hold great promise for the modern nanobiomedicine. In order to realize a ;one-stone-two-birds; strategy, we report a green, economic, one-pot method in this article for synthesizing photoluminescent C-dots by hydrothermal treatment of wheat straw. Using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), we show that the as-prepared C-dots are amorphous in structure and are mainly composed of carbon. Their tiny size (<2 nm), combined with the characteristic excitation-dependent relatively bright emission, and robust photostability made the C-dots a potential biocompatible nanomaterial for bio-applications. We have experimentally demonstrated their potential applications in biomedical labeling, imaging, and sensing/detecting. The high yield (∼20%) of C-dots from wheat straw may suggest a new economic strategy for recycling biowaste.

  5. EEG predictors of covert vigilant attention

    Science.gov (United States)

    Martel, Adrien; Dähne, Sven; Blankertz, Benjamin

    2014-06-01

    Objective. The present study addressed the question whether neurophysiological signals exhibit characteristic modulations preceding a miss in a covert vigilant attention task which mimics a natural environment in which critical stimuli may appear in the periphery of the visual field. Approach. Subjective, behavioural and encephalographic (EEG) data of 12 participants performing a modified Mackworth Clock task were obtained and analysed offline. The stimulus consisted of a pointer performing regular ticks in a clockwise sequence across 42 dots arranged in a circle. Participants were requested to covertly attend to the pointer and press a response button as quickly as possible in the event of a jump, a rare and random event. Main results. Significant increases in response latencies and decreases in the detection rates were found as a function of time-on-task, a characteristic effect of sustained attention tasks known as the vigilance decrement. Subjective sleepiness showed a significant increase over the duration of the experiment. Increased activity in the α-frequency range (8-14 Hz) was observed emerging and gradually accumulating 10 s before a missed target. Additionally, a significant gradual attenuation of the P3 event-related component was found to antecede misses by 5 s. Significance. The results corroborate recent findings that behavioural errors are presaged by specific neurophysiological activity and demonstrate that lapses of attention can be predicted in a covert setting up to 10 s in advance reinforcing the prospective use of brain-computer interface (BCI) technology for the detection of waning vigilance in real-world scenarios. Combining these findings with real-time single-trial analysis from BCI may pave the way for cognitive states monitoring systems able to determine the current, and predict the near-future development of the brain's attentional processes.

  6. A study of the lunisolar secular resonance $2dot{omega}+dot{Omega}=0$

    Directory of Open Access Journals (Sweden)

    Alessandra eCelletti

    2016-03-01

    Full Text Available The dynamics of small bodies around the Earth has gained a renewed interest,since the awareness of the problems that space debris can cause in thenearby future. A relevant role in space debris is played by lunisolarsecular resonances, which might contribute to an increase of the orbitalelements, typically of the eccentricity. We concentrate our attention onthe lunisolar secular resonance described by the relation$2dot{omega}+dot{Omega}=0$, where $omega$ and $Omega$ denotethe argument of perigee and the longitude of the ascending node of the space debris.We introduce three different models with increasing complexity. We show that the growth in eccentricity, as observed in space debris located in the MEO region at the inclination about equal to $56^circ$, can be explained as a natural effect of the secular resonance $2dot{omega}+dot{Omega}=0$, while the chaotic variations of the orbital parameters are the result of interaction and overlapping of nearby resonances.

  7. Early life cognitive abilities and body weight: cross-sectional study of the association of inhibitory control, cognitive flexibility, and sustained attention with BMI percentiles in primary school children.

    Science.gov (United States)

    Wirt, Tamara; Schreiber, Anja; Kesztyüs, Dorothea; Steinacker, Jürgen M

    2015-01-01

    The objective of this study was to investigate the association of different cognitive abilities with children's body weight adjusted for further weight influencing sociodemographic, family, and lifestyle factors. Cross-sectional data of 498 primary school children (7.0 ± 0.6 years; 49.8% boys) participating in a health promotion programme in southwest Germany were used. Children performed a computer-based test battery (KiTAP) including an inhibitory control task (Go-Nogo paradigm), a cognitive flexibility task, and a sustained attention task. Height and weight were measured in a standardized manner and converted to BMI percentiles based on national standards. Sociodemographic features (migration background and parental education), family characteristics (parental body weight), and children's lifestyle (TV consumption, physical activity, consumption of sugar-sweetened beverages and breakfast habits) were assessed via parental questionnaire. A hierarchical regression analysis revealed inhibitory control and cognitive flexibility to be significant cognitive predictors for children's body weight. There was no association concerning sustained attention. The findings suggest that especially cognitive abilities known as executive functions (inhibitory control and cognitive flexibility) are associated with children's body weight. Future longitudinal and intervention studies are necessary to investigate the directionality of the association and the potential of integrating cognitive training in obesity prevention strategies. This trial is registered with ClinicalTrials.gov DRKS00000494.

  8. Reward devaluation: Dot-probe meta-analytic evidence of avoidance of positive information in depressed persons.

    Science.gov (United States)

    Winer, E Samuel; Salem, Taban

    2016-01-01

    Cognitive theories of depression and anxiety have traditionally emphasized the role of attentional biases in the processing of negative information. The dot-probe task has been widely used to study this phenomenon. Recent findings suggest that biased processing of positive information might also be an important aspect of developing psychopathological symptoms. However, despite some evidence suggesting persons with symptoms of depression and anxiety may avoid positive information, many dot-probe studies have produced null findings. The present review used conventional and novel meta-analytic methods to evaluate dot-probe attentional biases away from positive information and, for comparison, toward negative information, in depressed and anxious individuals. Results indicated that avoidance of positive information is a real effect exhibiting substantial evidential value among persons experiencing psychopathology, with individuals evidencing primary symptoms of depression clearly demonstrating this effect. Different theoretical explanations for these findings are evaluated, including those positing threat-processing structures, even-handedness, self-regulation, and reward devaluation, with the novel theory of reward devaluation emphasized and expanded. These novel findings and theory suggest that avoidance of prospective reward helps to explain the cause and sustainability of depressed states. Suggestions for future research and methodological advances are discussed. (c) 2015 APA, all rights reserved).

  9. Attention, Predation, Counterintuition

    DEFF Research Database (Denmark)

    Clasen, Mathias

    2012-01-01

    of Dracula to account for the novel’s impact and resilience. Dracula connected squarely with late-Victorian anxieties, but the novel also appeals to trans-historical adaptive dispositions. I analyze Stoker’s use of narrative strategies to grab and sustain attention, and Count Dracula as a supercharged...

  10. From DOT to Dotty

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    - Module types are interfaces, which can be abstracted. In this talk Martin will present DOT, a particularly simple calculus that can express systems following these principles. DOT has been developed as the foundation of the next version of Scala. He will also report on dotty, a new Scala compiler that implements the constructs of DOT in its core data structures and that uses the lessons learned to drive Scala’s evolution.

  11. Sustained Satellite Missions for Climate Data Records

    Science.gov (United States)

    Halpern, David

    2012-01-01

    Satellite CDRs possess the accuracy, longevity, and stability for sustained moni toring of critical variables to enhance understanding of the global integrated Earth system and predict future conditions. center dot Satellite CDRs are a critical element of a global climate observing system. center dot Satellite CDRs are a difficult challenge and require high - level managerial commitment, extensive intellectual capital, and adequate funding.

  12. The attentional modulation of the flash-lag effect

    Directory of Open Access Journals (Sweden)

    M.V.C. Baldo

    2002-08-01

    Full Text Available If a dot is flashed in perfect alignment with a pair of dots rotating around the visual fixation point, most observers perceive the rotating dots as being ahead of the flashing dot (flash-lag effect. This perceptual effect has been interpreted to result from the perceptual extrapolation of the moving dots, the differential visual latencies between flashing and moving stimuli, as well as the modulation of attentional mechanisms. Here we attempted to uncouple the attentional effects brought about by the spatial predictability of the flashing dot from the sensory effects dependent on its visual eccentricity. The stimulus was a pair of dots rotating clockwise around the fixation point. Another dot was flashed at either the upper right or the lower left of the visual field according to three separate blocked situations: fixed, alternate and random positions. Twenty-four participants had to judge, in all three situations, the location of the rotating dots in relation to the imaginary line connecting the flashing dot and the fixation point at the moment the dot was flashed. The flash-lag effect was observed in all three situations, and a clear influence of the spatial predictability of the flashing dot on the magnitude of the perceptual phenomenon was revealed, independently of sensory effects related to the eccentricity of the stimulus in the visual field. These findings are consistent with our proposal that, in addition to sensory factors, the attentional set modulates the magnitude of the differential latencies that give rise to the flash-lag phenomenon.

  13. Lean maturity, lean sustainability

    DEFF Research Database (Denmark)

    Jørgensen, Frances; Matthiesen, Rikke; Nielsen, Jacob

    2007-01-01

    Although lean is rapidly growing in popularity, its implementation is far from problem free and companies may experience difficulties sustaining long term success. In this paper, it is suggested that sustainable lean requires attention to both performance improvement and capability development...... that support lean capability development and consequently, lean sustainability....

  14. Quantum Dots: Theory

    Energy Technology Data Exchange (ETDEWEB)

    Vukmirovic, Nenad; Wang, Lin-Wang

    2009-11-10

    This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.

  15. Hybrid Double Quantum Dots

    DEFF Research Database (Denmark)

    Sherman, D.; Yodh, J. S.; Albrecht, S. M.

    2016-01-01

    Epitaxial semiconductor-superconductor hybrid materials are an excellent basis for studying mesoscopic and topological superconductivity, as the semiconductor inherits a hard superconducting gap while retaining tunable carrier density. Here, we investigate double-quantum-dot devices made from InA...... that the individual dots host weakly hybridized Majorana modes....

  16. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    the linear-conductance regime. The second work deals with the ratio of coherent processes in transport through quantum dots. To this end, a quantum dot is embedded in one of the arms of an Aharonov-Bohm interferometer. In former theoretical as well as experimental works it has been observed that an important source of decoherence are cotunneling processes that flip the dot's spin. In order to elucidate the role of spin in more detail, we assume one of the leads to be ferromagnetic and the other one to be normal. The main motivations of our work are the two questions: (1) What fraction of the total current through a single-level quantum dot weakly coupled to the electrodes is coherent? (2) How and under which circumstances can this fraction be extracted from a current measurement in an Aharonov-Bohm setup? The measurable quantity in such an experiment is the magnetic-flux dependent ratio of the total current. It turns out that the answers of the two questions strongly depend on the dot level position, the polarization of the ferromagnet, and the transport direction. Especially the flux-dependent and the coherent ratios are not necessarily the same. The main motivation of the third work is to identify crossed Andreev reflection in quantum dots, that is, a Cooper pair splits into two single electrons, which are transferred into different quantum dots in one coherent process. We consider a setup, where two quantum dots are tunnel coupled to the same superconductor and each dot is additionally coupled to a normal conductor. In previous works a bias voltage has been applied between the superconductor and the normal conductors. Then, three processes sustain transport. Beside crossed Andreev reflection also local Andreev reflection, where both electrons of the Cooper pair tunnel into the same dot, and single-particle tunneling occur. This complicates the identification of crossed Andreev reflection. Therefore, we propose the transport mechanism of adiabatic pumping in

  17. Synthesis of quantum dots

    Science.gov (United States)

    McDaniel, Hunter

    2017-10-17

    Common approaches to synthesizing alloyed quantum dots employ high-cost, air-sensitive phosphine complexes as the selenium precursor. Disclosed quantum dot synthesis embodiments avoid these hazardous and air-sensitive selenium precursors. Certain embodiments utilize a combination comprising a thiol and an amine that together reduce and complex the elemental selenium to form a highly reactive selenium precursor at room temperature. The same combination of thiol and amine acts as the reaction solvent, stabilizing ligand, and sulfur source in the synthesis of quantum dot cores. A non-injection approach may also be used. The optical properties of the quantum dots synthesized by this new approach can be finely tuned for a variety of applications by controlling size and/or composition of size and composition. Further, using the same approach, a shell can be grown around a quantum dot core that improves stability, luminescence efficiency, and may reduce toxicity.

  18. Are You Paying Attention?

    DEFF Research Database (Denmark)

    2016-01-01

    and sustained. To study such attention practices, 16 semi-structured interviews with adult Danes are carried out. Through a thematic analysis of these interviews, the chapter explores how ways of attending relate to individual media and how patterns of daily life enable some practices and constrain others......A still understudied area in media research is how people pay attention to news in daily life. To do so, the chapter develops a theoretical framework grounded in news audience research and practice theory. This framework conceptualizes practices as different ways in which attention is directed....... In the concluding discussion, the chapter relates the findings to further perspectives on attention to news specifically and media content more generally. Accordingly, this chapter contributes to cross-media news research by analyzing ways in which people attend to news and how these ways of attending vary across...

  19. One-step, green, and economic synthesis of water-soluble photoluminescent carbon dots by hydrothermal treatment of wheat straw, and their bio-applications in labeling, imaging, and sensing

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Ming; Zhong, Ruibo; Gao, Haiyang; Li, Wanrong; Yun, Xiaoling; Liu, Jingran; Zhao, Xinmin; Zhao, Guofen; Zhang, Feng, E-mail: fengzhang1978@hotmail.com

    2015-11-15

    Graphical abstract: Water-soluble photoluminescent carbon dots can be synthesized simply by a green, economic and one-pot hydrothermal treatment of wheat straw with ∼20% yield, in addition to the compact size and robust photostability they are experimentally demonstrated for multiplexed applications such as sensing ions and labeling and imaging for inorganic nanostructures, cells and even nematodes. The converting biomass wastes to promising biocompatible nanomaterials could be a “one-stone-two-birds” strategy to other carbon-containing biomass waste for a highly effectively carbon recycling use and sustainable energy and environment future. - Highlights: • Photoluminescent carbon dots can be synthesized by wheat straw with about 20% yield. • Carbon dots can be used for both nonliving and living labeling, imaging, and sensing. • Carbon dots can be used as a fluorescent ink. - Abstract: The use of biomass as renewable and sustainable energy source has attracted the attention of politics and research and development (R&D) facilities around the world. Agricultural straw acts as a typical biowaste, which still needs highly effective recycling to save the biomass urgently at present. Photoluminescent carbon dots (C-dots) are novel biocompatible nanomaterials that have been proved to be produced from many carbon-abundant materials and hold great promise for the modern nanobiomedicine. In order to realize a “one-stone-two-birds” strategy, we report a green, economic, one-pot method in this article for synthesizing photoluminescent C-dots by hydrothermal treatment of wheat straw. Using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), we show that the as-prepared C-dots are amorphous in structure and are mainly composed of carbon. Their tiny size (<2 nm), combined with the characteristic excitation-dependent relatively bright emission, and robust photostability made the C-dots a potential biocompatible nanomaterial for bio-applications. We

  20. Visual attention: a rhythmic process?

    Science.gov (United States)

    VanRullen, Rufin

    2013-12-16

    Vision involves constant exploration of the environment by eye movements. Recent evidence suggests that a rhythmic form of exploration also occurs under covert attention, in the absence of eye movements. Sustained attention naturally fluctuates, with a periodicity in the theta (4-8 Hz) frequency range. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Changes in emotional distress, short term memory, and sustained attention following 6 and 12 sessions of progressive muscle relaxation training in 10-11 years old primary school children.

    Science.gov (United States)

    Hashim, Hairul Anuar; Zainol, Nurul Ain

    2015-01-01

    This study compared the effects of 6 and 12 sessions of relaxation training on emotional distress, short-term memory, and sustained attention in primary school children. Participants (N = 132) aged 10 and 11 years old participated in this study. All participants and their parents provided written informed consent. Participants completed the measurement instruments before and after the completion of relaxation training. Nearly half (49%) of all respondents reported moderate to extremely severe stress, and 80 and 61% reported moderate to extremely severe anxiety and depression, respectively. The results of a one-way analysis of variance revealed a significant difference among the groups in mean changes in short-term memory. A greater memory increase was observed in the 12-session than in the six-session and no-training group. It can be conceived that 12-session of training should be considered when prescribing relaxation regimens as a nonspecific clinical treatment (i.e. for healthy students).

  2. Visual attention in the first years: typical development and developmental disorders

    National Research Council Canada - National Science Library

    ATKINSON, JANETTE; BRADDICK, OLIVER

    2012-01-01

    ...: selective attention, sustained attention, and attentional (executive) control. These systems overlap with dorsal cortical visual streams and their disorders are related to the general hypothesis...

  3. A low-cost cognitive rehabilitation with a commercial video game improves sustained attention and executive functions in multiple sclerosis: a pilot study.

    Science.gov (United States)

    De Giglio, Laura; De Luca, Francesca; Prosperini, Luca; Borriello, Giovanna; Bianchi, Valentina; Pantano, Patrizia; Pozzilli, Carlo

    2015-06-01

    To evaluate the effectiveness of a home-based cognitive rehabilitation (CR) program based on the video game Dr Kawashima's Brain Training (DKBT; Nintendo, Japan), in improving attention, processing speed, and working memory of patients with multiple sclerosis (MS). This was a randomized, wait-list control study. Patients with MS and failure in at least one between Stroop Test (ST), Paced Auditory Serial Addition Test (PASAT), and Symbol Digit Modalities Test (SDMT) were submitted to an 8-week home-based CR program playing DKBT. Patients were evaluated at baseline and after DKBT by the aforementioned tests, by the Modified Fatigue Impact Scale (MFIS) and by the MS Quality of Life-54 questionnaire (MSQoL-54). Fifty-two 52 patients were screened for eligibility; 35 (mean [standard deviation] age of 43.9 [8.4] years, median Expanded Disability Status Scale score of 2.0 (range = 2.0-6.0) were randomly assigned to the intervention group (n = 18) or wait-list control group (n = 17). ANCOVA analysis showed a significant effect of DKBT on ST (F = 5.027; P = .034; F(2) = 0.210), SDMT (F = 4.240; P = .049; F(2) = 0.177), and on some subscales of MSQoL-54. The PASAT and cognitive subscale of MFIS also showed an improvement, but this was just not significant (F = 4.104, P = .054, F(2) = 0.171, and F = 4.226, P = .054, F(2) = 0.237, respectively). We suggest that a home-based DKBT program may improve cognitive functions, some aspects of QoL, and cognitive fatigue in patients with MS. © The Author(s) 2014.

  4. Pharmaceutical and biomedical applications of quantum dots.

    Science.gov (United States)

    Bajwa, Neha; Mehra, Neelesh K; Jain, Keerti; Jain, Narendra K

    2016-05-01

    Quantum dots (QDs) have captured the fascination and attention of scientists due to their simultaneous targeting and imaging potential in drug delivery, in pharmaceutical and biomedical applications. In the present study, we have exhaustively reviewed various aspects of QDs, highlighting their pharmaceutical and biomedical applications, pharmacology, interactions, and toxicological manifestations. The eventual use of QDs is to dramatically improve clinical diagnostic tests for early detection of cancer. In recent years, QDs were introduced to cell biology as an alternative fluorescent probe.

  5. Quantum dot molecules

    CERN Document Server

    Wu, Jiang

    2014-01-01

    This book reviews recent advances in the exciting and rapidly growing field of quantum dot molecules (QDMs). It offers state-of-the-art coverage of novel techniques and connects fundamental physical properties with device design.

  6. Carbon dots based FRET for the detection of DNA damage.

    Science.gov (United States)

    Kudr, Jiri; Richtera, Lukas; Xhaxhiu, Kledi; Hynek, David; Heger, Zbynek; Zitka, Ondrej; Adam, Vojtech

    2017-06-15

    Here, we aimed our attention at the synthesis of carbon dots (C-dots) with the ability to interact with DNA to suggest an approach for the detection of DNA damage. Primarily, C-dots modified with amine moieties were synthesized using the one-step microwave pyrolysis of citric acid in the presence of diethylenetriamine. The C-dots showed strong photoluminescence with a quantum yield of 4%. In addition, the C-dots (2.8±0.8nm) possessed a good colloidal stability and exhibited a positive surface charge (ζ=36mV) at a neutral pH. An interaction study of the C-dots and the DNA fragment of λ bacteriophage was performed, and the DNA binding resulted in changes to the photoluminescent and absorption properties of the C-dots. A binding of the C-dots to DNA was also observed as a change to DNA electrophoretic mobility and a decreased ability to intercalate ethidium bromide (EtBr). Moreover, the Förster (or fluorescence) resonance energy transfer (FRET) between the C-dots and EtBr was studied, in which the C-dots serve as an excitation energy donor and the EtBr serves as an acceptor. When DNA was damaged using ultraviolet (UV) radiation (λ=254nm) and hydroxyl radicals, the intensity of the emitted photoluminescence at 612nm significantly decreased. The concept was proved on analysis of the genomic DNA from PC-3 cells and DNA isolated from melanoma tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Graphene quantum dots

    CERN Document Server

    Güçlü, Alev Devrim; Korkusinski, Marek; Hawrylak, Pawel

    2014-01-01

    This book reflects the current status of theoretical and experimental research of graphene based nanostructures, in particular quantum dots, at a level accessible to young researchers, graduate students, experimentalists and theorists. It presents the current state of research of graphene quantum dots, a single or few monolayer thick islands of graphene. It introduces the reader to the electronic and optical properties of graphite, intercalated graphite and graphene, including Dirac fermions, Berry's phase associated with sublattices and valley degeneracy, covers single particle properties of

  8. Stimuli responsive polymer/quantum dot hybrid platforms modified at the nanoscale

    NARCIS (Netherlands)

    Tagit, O.

    2010-01-01

    Quantum dots, QDs, receive growing attention from many research disciplines owing to their advantages as fluorescent probes including their nanoscale size (similar to biomolecules), high quantum yield and molar extinction coefficients, versatility in surface modification, broad excitation spectra

  9. Attention visuelle

    OpenAIRE

    Rousserie, Marie

    2015-01-01

    William James, philosophe et psychologue américain, est le premier à parler de l’attention en 1890 dans son livre The Principles of Psychology : il dit que c’est un concept connu mais dont personne ne saurait en donner une définition précise. Il la définit alors ainsi : « L'attention est la prise de possession par l'esprit, sous une forme claire et vive, d'un objet ou d'une suite de pensées parmi plusieurs qui semblent possibles […] Elle implique le retrait de certains objets afin de traiter ...

  10. Dynamic Multitasking Countermeasures to Improve Sustained Attention

    Science.gov (United States)

    2013-07-12

    PROGRAM ELEMENT NUMBER 5b. GRANT NUMBER 5a. CONTRACT NUMBER Form Approved OMB NO. 0704-0188 3. DATES COVERED (From - To) - UU UU UU UU 06-07-2015 1...Subsequently a series of MLMs were fit with the following characteristics: The model was run allowing for the following predictors: -Drive Condition...power.  This  produced  a  distribution  of  estimates  that  was  more   liky  to  match  the  assumptions  of   MLM

  11. Attention Sensor

    NARCIS (Netherlands)

    Börner, Dirk; Kalz, Marco; Specht, Marcus

    2014-01-01

    This software sketch was used in the context of an experiment for the PhD project “Ambient Learning Displays”. The sketch comprises a custom-built attention sensor. The sensor measured (during the experiment) whether a participant looked at and thus attended a public display. The sensor was built

  12. Electrophysiological evidence of attentional biases in social anxiety disorder

    NARCIS (Netherlands)

    Müller, E.M.; Hofmann, S.G.; Santesso, D.L.; Meuret, A.E.; Bitran, S.; Pizzagalli, D.A.

    2009-01-01

    Background. Previous studies investigating attentional biases in social anxiety disorder (SAD) have yielded mixed results. Recent event-related potential (ERP) studies using the dot-probe paradigm in non-anxious participants have shown that the P1 component is sensitive to visuospatial attention

  13. Attentional Patterns Involved in Coping Strategies in a Sport Context

    Science.gov (United States)

    Bardel, Marie-Heloise; Woodman, Tim; Colombel, Fabienne; Le Scanff, Christine

    2012-01-01

    We investigated the relationship between coping strategies and attentional bias after a sport competition. We administered the Ways of Coping Checklist (Paulhan, Nuissier, Quintard, Cousson, & Bourgeois, 1994) to 145 athletes immediately after they had participated in a sport competition. We also assessed attentional bias using a dot probe…

  14. Sustainability in Software Engineering

    NARCIS (Netherlands)

    Wolfram, N.J.E.; Lago, P.; Osborne, Francesco

    2017-01-01

    The intersection between software engineering research and issues related to sustainability and green IT has been the subject of increasing attention. In spite of that, we observe that sustainability is still not clearly defined, or understood, in the field of software engineering. This lack of

  15. Double quantum dot memristor

    Science.gov (United States)

    Li, Ying; Holloway, Gregory W.; Benjamin, Simon C.; Briggs, G. Andrew D.; Baugh, Jonathan; Mol, Jan A.

    2017-08-01

    Memristive systems are generalizations of memristors, which are resistors with memory. In this paper, we present a quantum description of quantum dot memristive systems. Using this model we propose and experimentally demonstrate a simple and practical scheme for realizing memristive systems with quantum dots. The approach harnesses a phenomenon that is commonly seen as a bane of nanoelectronics, i.e., switching of a trapped charge in the vicinity of the device. We show that quantum dot memristive systems have hysteresis current-voltage characteristics and quantum jump-induced stochastic behavior. While our experiment requires low temperatures, the same setup could, in principle, be realized with a suitable single-molecule transistor and operated at or near room temperature.

  16. Assessment of Attention in Preschoolers

    Science.gov (United States)

    Mahone, E.M.; Schneider, H.E.

    2012-01-01

    In the past two decades, there has been an increased interest in the assessment and treatment of preschool children presenting with concerns about attention problems. This article reviews the research and clinical literature involving assessment of attention and related skills in the preschool years. While inattention among preschoolers is common, symptoms alone do not necessarily indicate a disorder, and most often represent a normal variation in typical preschool child development. Thus, accurate identification of “disordered” attention in preschoolers can be challenging, and development of appropriate, norm-referenced tests of attention for preschoolers is also difficult. The current review suggests that comprehensive assessment of attention and related functions in the preschool child should include thorough review of the child’s history, planned observations, and formal psychometric testing. The three primary methods of psychometric assessment that have been used to characterize attentional functioning in preschool children include performance-based tests, structured caregiver interviews, and rating scales (parent, teacher, and clinician). Among performance-based methods for measurement of attention in the preschool years, tests have been developed to assess sustained attention, selective (focused) attention, span of attention (encoding/manipulation), and (top-down) controlled attention—including freedom from distractibility and set shifting. Many of these tests remain experimental in nature, and review of published methods yields relatively few commercially available, nationally normed tests of attention for preschoolers, and an overall dearth of reliability and validity studies on the available measures. PMID:23090646

  17. Hexagonal graphene quantum dots

    KAUST Repository

    Ghosh, Sumit

    2016-12-05

    We study hexagonal graphene quantum dots, using density functional theory, to obtain a quantitative description of the electronic properties and their size dependence, considering disk and ring geometries with both armchair and zigzag edges. We show that the electronic properties of quantum dots with armchair edges are more sensitive to structural details than those with zigzag edges. As functions of the inner and outer radii, we find in the case of armchair edges that the size of the band gap follows distinct branches, while in the case of zigzag edges it changes monotonically. This behaviour is further analyzed by studying the ground state wave function and explained in terms of its localisation.

  18. Quantum dot solar cells

    CERN Document Server

    Wu, Jiang

    2013-01-01

    The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of variou

  19. Teste de Habilidade de Atenção Auditiva Sustentada (THAAS em crianças de sete anos com fissura labiopalatina Sustained Auditory Attention Ability Test (SAAAT in seven-year-old children with cleft lip and palate

    Directory of Open Access Journals (Sweden)

    Isabel Cristina Cavalcanti Lemos

    2010-04-01

    Full Text Available A fissura labiopalatina é um indicador de risco para alterações de orelha média, o que pode prejudicar o desenvolvimento de habilidades auditivas tais como a atenção, que é essencial para o aprendizado de novas habilidades, comunicação oral e escrita. O estudo do processo atencional na população com fissura labiopalatina é algo recente e pouco explorado na literatura específica consultada, assim, este trabalho poderá contribuir com novos subsídios na área, uma vez que tem como objetivo verificar o desempenho de crianças com fissura labiopalatina no Teste de Habilidade de Atenção Auditiva Sustentada (THAAS. MATERIAL E MÉTODO: Comparação do desempenho no THAAS de crianças com e sem fissura labiopalatina. Estudo Prospectivo. RESULTADOS: Para estudar a associação entre os resultados do THAAS e as variáveis grupo e gênero foi utilizado um modelo de análise de variância (ANOVA com dois fatores, com o qual foi possível observar que o grupo com fissura labiopalatina apresentou média 2,5 unidades maior que o grupo controle, esta diferença encontra-se entre 0,7 e 4,4 com 95% de confiança. CONCLUSÃO: As crianças com fissura labiopalatina apresentaram desempenho no THAAS inferior àquelas sem essa anomalia craniofacial apenas para o decréscimo da vigilância.Cleft lip and palate (CLP is a risk indicator to middle ear alterations, which may damage the development of auditory abilities such as attention that is essential to learn new skills, oral and written communication. Studies on attention process with CLP population are recent and poorly explored in the specific literature. Thus, this study aims to contribute with new subsidies in the field as it investigates the performance of children with CLP in Sustained Auditory Attention Ability Test (SAAAT. MATERIAL AND METHOD: Comparison of SAAAT performance between children with CLP and children without it. Prospective study. RESULTS: ANOVA was used as variance analysis model

  20. From sustainable buildings to sustainable business

    OpenAIRE

    Mia Andelin

    2012-01-01

    The United Nations Environment Program (UNEP) Sustainable Buildings & Climate Initiative reports that buildings are responsible for more than 40 percent of global energy use and over one third of global greenhouse gas (GHG) emissions. The construction and real estate sector has the potential to play a significant role in the response to climate change. During the latest years the increase in attention to sustainability and green building by planners, developers, and investors has been remarka...

  1. RedDots Replayed

    DEFF Research Database (Denmark)

    Kinnunen, Tomi; Sahidullah, Md; Falcone, Mauro

    2017-01-01

    the protection of text-dependent ASV systems from replay attacks in the face of variable recording and playback conditions. Derived from the re-recording of the original RedDots database, the effort is aligned with that in text-dependent ASV and thus well positioned for future assessments of replay spoofing...

  2. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.

    2006-01-01

    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small

  3. White dots do matter

    DEFF Research Database (Denmark)

    Soeken, Mathias; Thomsen, Michael Kirkedal

    2013-01-01

    Toffoli circuits. We also show how to use these rules to derive more complex formulas. The major difference compared to existing approaches is the use of negative controls (white dots), which significantly increases the algebraic strength. We show how existing optimisation approaches can be adapted...

  4. Assessing sustainable remediation frameworks using sustainability principles.

    Science.gov (United States)

    Ridsdale, D Reanne; Noble, Bram F

    2016-12-15

    The remediation industry has grown exponentially in recent decades. International organizations of practitioners and remediation experts have developed several frameworks for integrating sustainability into remediation projects; however, there has been limited attention to how sustainability is approached and operationalized in sustainable remediation frameworks and practices - or whether sustainability plays any meaningful role at all in sustainable remediation. This paper examines how sustainability is represented in remediation frameworks and the guidance provided for practical application. Seven broad sustainability principles and review criteria are proposed and applied to a sample of six international remediation frameworks. Not all review criteria were equally satisfied and none of the frameworks fully met all criteria; however, the best performing frameworks were those identified as sustainability remediation frameworks. Intra-generational equity was addressed by all frameworks. Integrating social, economic and biophysical components beyond triple-bottom-line indicators was explicitly addressed only by the sustainable remediation frameworks. No frameworks provided principle- or rule-based guidance for dealing with trade-offs in sustainability decisions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Enhanced photoluminescence and characterization of multicolor carbon dots using plant soot as a carbon source.

    Science.gov (United States)

    Tan, Mingqian; Zhang, Lingxin; Tang, Rong; Song, Xiaojie; Li, Yimin; Wu, Hao; Wang, Yanfang; Lv, Guojun; Liu, Wanfa; Ma, Xiaojun

    2013-10-15

    Carbon dots (C-dots) are a class of novel fluorescent nanomaterials, which have drawn great attention for their potential applications in bio-nanotechnology. Multicolor C-dots have been synthesized by chemical nitric acid oxidation using the reproducible plant soot as raw material. TEM analysis reveals that the prepared C-dots have an average size of 3.1 nm. The C-dots are well dispersed in aqueous solution and are strongly fluorescent under the irradiation of ultra-violet light. X-ray photoelectron spectroscopy characterization demonstrates that the O/C atomic ratio for C-dots change to from 0.207 to 0.436 due to the chemical oxidation process. The photo bleaching experiment reveals that the C-dots show excellent photostability as compared with the conventional organic dyes, fluorescein and rhodamine B. The fluorescence intensity of the C-dots did not change significantly in the pH range of 3-10. To further enhance the fluorescence quantum yield, the C-dots were surface modified with four types of passivation ligands, 4,7,10-trioxa-1,13-tridecanediamine (TTDDA), poly-L-lysine (PLL), cysteine and chitosan and the fluorescence quantum yields of the TTDDA, PLL, cysteine and chitosan passivated C-dots were improved 1.53-, 5.94-, 2.00- and 3.68-fold, respectively. Fourier-transform infrared (FTIR) spectra were employed to characterize the surface groups of the C-dots. The bio-application of the C-dots as fluorescent bio-probes was evaluated in cell imaging and ex vivo fish imaging, which suggests that the C-dots may have potential applications in biolabeling and bioimaging. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Differential Long-Term Effects of Haloperidol and Risperidone on the Acquisition and Performance of Tasks of Spatial Working and Short-Term Memory and Sustained Attention in Rats

    Science.gov (United States)

    Hutchings, Elizabeth J.; Waller, Jennifer L.

    2013-01-01

    A common feature of the neuropsychiatric disorders for which antipsychotic drugs are prescribed is cognitive dysfunction, yet the effects of long-term antipsychotic treatment on cognition are largely unknown. In the current study, we evaluated the effects of long-term oral treatment with the first-generation antipsychotic haloperidol (1.0 and 2.0 mg/kg daily) and the second-generation antipsychotic risperidone (1.25 and 2.5 mg/kg daily) on the acquisition and performance of two radial-arm maze (RAM) tasks and a five-choice serial reaction-time task (5C-SRTT) in rats during days 15–60 and 84–320 days of treatment, respectively. In the RAM, neither antipsychotic significantly affected the acquisition or performance of a spatial win shift or a delayed non–match-to-position task. Conversely, in the rats administered 5C-SRTT, haloperidol was associated with profound deficits in performance, and the subjects were not able to progress through all stages of task acquisition. Depending on the dose, risperidone was associated with a greater number of trials to meet specific performance criteria during task acquisition compared with vehicle-treated controls; however, most subjects were eventually able to achieve all levels of task acquisition. Both haloperidol and risperidone also increased the number of perseverative and time-out responses during certain stages of task acquisition, and the response and reward latencies were slightly higher than controls during several stages of the study. These results in rats suggest that while long-term treatment with haloperidol or risperidone may not significantly affect spatial working or short-term memory, both antipsychotics can (depending on dose) impair sustained attention, decrease psychomotor speed, increase compulsive-type behaviors, and impair cognitive flexibility. PMID:24042161

  7. Dissociations between developmental dyslexias and attention deficits

    Science.gov (United States)

    Lukov, Limor; Friedmann, Naama; Shalev, Lilach; Khentov-Kraus, Lilach; Shalev, Nir; Lorber, Rakefet; Guggenheim, Revital

    2014-01-01

    We examine whether attention deficits underlie developmental dyslexia, or certain types of dyslexia, by presenting double dissociations between the two. We took into account the existence of distinct types of dyslexia and of attention deficits, and focused on dyslexias that may be thought to have an attentional basis: letter position dyslexia (LPD), in which letters migrate within words, attentional dyslexia (AD), in which letters migrate between words, neglect dyslexia, in which letters on one side of the word are omitted or substituted, and surface dyslexia, in which words are read via the sublexical route. We tested 110 children and adults with developmental dyslexia and/or attention deficits, using extensive batteries of reading and attention. For each participant, the existence of dyslexia and the dyslexia type were tested using reading tests that included stimuli sensitive to the various dyslexia types. Attention deficit and its type was established through attention tasks assessing sustained, selective, orienting, and executive attention functioning. Using this procedure, we identified 55 participants who showed a double dissociation between reading and attention: 28 had dyslexia with normal attention and 27 had attention deficits with normal reading. Importantly, each dyslexia with suspected attentional basis dissociated from attention: we found 21 individuals with LPD, 13 AD, 2 neglect dyslexia, and 12 surface dyslexia without attention deficits. Other dyslexia types (vowel dyslexia, phonological dyslexia, visual dyslexia) also dissociated from attention deficits. Examination of 55 additional individuals with both a specific dyslexia and a certain attention deficit found no attention function that was consistently linked with any dyslexia type. Specifically, LPD and AD dissociated from selective attention, neglect dyslexia dissociated from orienting, and surface dyslexia dissociated from sustained and executive attention. These results indicate that

  8. Sustainability curricula in design education

    NARCIS (Netherlands)

    Casais, M.; Christiaans, H.H.C.M.; Almendra, R.

    2012-01-01

    While sustainability in Design finds much attention in the literature, the education of sustainability in Design courses lacks discussion regarding curricula and importance. In an attempt to map the way sustainability is taught in Design Bachelor and Master Courses in the European Union, we began

  9. Attention Retention

    DEFF Research Database (Denmark)

    Kravchenko, Mariia; Cass, Andrew Knox

    2017-01-01

    , using the findings, introduce video for flipped classes, or online teaching. Taking 5 iterations of an action research approach the authors present the techniques and principles for making an interactive video and clear examples of lesson design. The research was conducted at a Danish higher education...... educational outcomes and student engagement. The researchers’ goal was to create and sustain smart, rich and active learning environments in both online and in classroom environments, and utilize existing content across both platforms.......As teachers look for ways to improve practice and enhance student engagement, referral to the literature leads to a dichotomy between specific activity and heavy academic research on metadata and learning analytics. This paper is intended to tread the pathway between the two so that teachers can...

  10. The effect of oxytocin on attention to angry and happy faces in chronic depression.

    Science.gov (United States)

    Domes, Gregor; Normann, Claus; Heinrichs, Markus

    2016-04-06

    Chronic depression is characterized by a high degree of early life trauma, psychosocial impairment, and deficits in social cognition. Undisturbed recognition and processing of facial emotions are basic prerequisites for smooth social interactions. Intranasal application of the neuropeptide oxytocin has been reported to enhance emotion recognition in neuropsychiatric disorders and healthy individuals. We therefore investigated whether oxytocin modulates attention to emotional faces in patients with chronic depression. In this double-blind, randomized, controlled study, 43 patients received a single dose of oxytocin or placebo nasal spray and were tested while fulfilling a facial dot probe task. We assessed reaction times to neutral probes presented at the location of one of two faces depicting happy, angry, or neutral expressions as a prime. When comparing reaction times to the congruent (prime and probe at the same location) with incongruent presentation of facial emotions, neither the placebo nor oxytocin group showed an attentional preference for emotional facial expressions in terms of a threat bias. However, oxytocin treatment did reveal two specific effects: it generally reduced the allocation of attention towards angry facial expressions, and it increased sustained attention towards happy faces, specifically under conditions of heightened awareness, i.e. trials with longer primes. We investigated a heterogeneous group of medicated male and female patients. We conclude that oxytocin does modulate basic factors of facial emotion processing in chronic depression. Our findings encourage further investigations assessing the therapeutic potential of oxytocin in chronic depression. EUDRA-CT 2010-020956-69 . Date registered: 23 February 2011.

  11. Dissociations between developmental dyslexias and attention deficits

    Directory of Open Access Journals (Sweden)

    Limor eLukov

    2015-01-01

    Full Text Available We examine whether attention deficits underlie developmental dyslexia, or certain types of dyslexia, by presenting double dissociations between the two. We took into account the existence of distinct types of dyslexia and of attention deficits, and focused on dyslexias that may be thought to have an attentional basis: letter position dyslexia (LPD, in which letters migrate within words, attentional dyslexia (AD, in which letters migrate between words, neglect dyslexia, in which letters on one side of the word are omitted or substituted, and surface dyslexia, in which words are read via the sublexical route.We tested 110 children and adults with developmental dyslexia and/or attention deficits, using extensive batteries of reading and attention.For each participant, the existence of dyslexia and the dyslexia type were tested using reading tests that included stimuli sensitive to the various dyslexia types. Attention deficit and its type was established through attention tasks assessing sustained, selective, orienting, and executive attention functioning. Using this procedure,we identified 55 participants who showed a double dissociation between reading and attention: 28 had dyslexia with normal attention and 27 had attention deficits with normal reading.Each dyslexia with suspected attentional basis dissociated from attention:21 individuals with LPD,13 AD,2 neglect dyslexia,and 12 surface dyslexia. Other dyslexia types(vowel dyslexia, phonological dyslexia, visual dyslexia also dissociated from attention deficits.Examination of 55 additional individuals with both a specific dyslexia and a certain attention deficit found no attention function that was consistently linked with any dyslexia type.Specifically, LPD and AD dissociated from selective attention, neglect dyslexia dissociated from orienting, and surface dyslexia dissociated from sustained and executive attention. These results indicate that visuospatial attention deficits do not underlie

  12. Nanocrystal quantum dots

    CERN Document Server

    Klimov, Victor I

    2010-01-01

    ""Soft"" Chemical Synthesis and Manipulation of Semiconductor Nanocrystals, J.A. Hollingsworth and V.I. Klimov Electronic Structure in Semiconductor Nanocrystals: Optical Experiment, D.J. NorrisFine Structure and Polarization Properties of Band-Edge Excitons in Semiconductor Nanocrystals, A.L. EfrosIntraband Spectroscopy and Dynamics of Colloidal Semiconductor Quantum Dots, P. Guyot-Sionnest, M. Shim, and C. WangMultiexciton Phenomena in Semiconductor Nanocrystals, V.I. KlimovOptical Dynamics in Single Semiconductor Quantum Do

  13. A tunable colloidal quantum dot photo field-effect transistor

    KAUST Repository

    Ghosh, Subir

    2011-01-01

    We fabricate and investigate field-effect transistors in which a light-absorbing photogate modulates the flow of current along the channel. The photogate consists of colloidal quantum dots that efficiently transfer photoelectrons to the channel across a charge-separating (type-II) heterointerface, producing a primary and sustained secondary flow that is terminated via electron back-recombination across the interface. We explore colloidal quantum dot sizes corresponding to bandgaps ranging from 730 to 1475 nm and also investigate various stoichiometries of aluminum-doped ZnO (AZO) channel materials. We investigate the role of trap state energies in both the colloidal quantum dot energy film and the AZO channel. © 2011 American Institute of Physics.

  14. Far-infrared edge modes in quantum dots

    Science.gov (United States)

    Lipparini, E.; Barberán, N.; Barranco, M.; Pi, M.; Serra, Ll.

    1997-11-01

    We have investigated edge modes of different multipolarity sustained by quantum dots submitted to external magnetic fields. We present a microscopic description based on a variational solution of the equation of motion for any axially symmetric confining potential and multipole mode. Numerical results for dots with different numbers of electrons, whose ground state is described within a local current density-functional theory, are discussed. Two sum rules, which are exact within this theory, are derived. In the limit of a large neutral dot at B=0, we show that the classical hydrodynamic dispersion law for edge waves ω(q) ~q ln (q0/q) holds when quantum and finite-size effects are taken into account.

  15. Attentional Bias in Math Anxiety

    Directory of Open Access Journals (Sweden)

    Orly eRubinsten

    2015-10-01

    Full Text Available Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety as well (i.e., a persistent negative reaction to math. Twenty seven participants (14 with high levels of math anxiety and 13 with low levels of math anxiety were presented with a novel computerized numerical version of the well established dot probe task. One of 6 types of prime stimuli, either math related or typically neutral, were presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks. Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in math anxiety. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words. These findings suggest that attentional bias is linked to unduly intense math anxiety symptoms.

  16. A Componential Analysis of Visual Attention in Children With ADHD.

    Science.gov (United States)

    McAvinue, Laura P; Vangkilde, Signe; Johnson, Katherine A; Habekost, Thomas; Kyllingsbæk, Søren; Bundesen, Claus; Robertson, Ian H

    2015-10-01

    Inattentive behaviour is a defining characteristic of ADHD. Researchers have wondered about the nature of the attentional deficit underlying these symptoms. The primary purpose of the current study was to examine this attentional deficit using a novel paradigm based upon the Theory of Visual Attention (TVA). The TVA paradigm enabled a componential analysis of visual attention through the use of a mathematical model to estimate parameters relating to attentional selectivity and capacity. Children's ability to sustain attention was also assessed using the Sustained Attention to Response Task. The sample included a comparison between 25 children with ADHD and 25 control children aged 9-13. Children with ADHD had significantly impaired sustained attention and visual processing speed but intact attentional selectivity, perceptual threshold and visual short-term memory capacity. The results of this study lend support to the notion of differential impairment of attentional functions in children with ADHD. © 2012 SAGE Publications.

  17. Latent Factors in Attention Emerge from 9 Years of Age among Elementary School Children

    OpenAIRE

    Ting Tao; Ligang Wang; Chunlei Fan; Wenbin Gao; Jiannong Shi

    2017-01-01

    We explored the development of attention among elementary school children. Three hundred and sixty-five primary school children aged 7–12 years completed seven attention tests (alertness, focused attention, divided attention, attentional switching, sustained attention, spatial attention, and supervisory attention). A factor analysis indicated that there was no stable construct of attention among 7- to 8-year-old children. However, from 9 years on, children’s attention could be separated into ...

  18. Stochastic clustered-dot dithering

    Science.gov (United States)

    Ostromoukhov, Victor; Hersch, Roger D.

    1999-10-01

    A new technique for building stochastic clustered-dot screens is being proposed. A large dither matrix comprising thousands of stochastically laid out screen dots is constructed by first laying out the screen dot centers. Screen dot centers are obtained by placing discrete disks of a chosen radius at free cell locations when traversing the dither array cells according to either a discretely rotated Hilbert space-filling curve or a random space-filling curve. After Delauney triangulation of the screen dot centers, the maximal surface of each screen dot is computed and isointensity regions are created. This isointensity map is converted into an antialiased gray scale image, i.e., into an array of preliminary threshold values. These threshold values are renumbered to obtain the threshold values of the final dither threshold array. By changing the disk radius, the screen dot size can be adapted to the characteristics of particular printing devices. Larger screen dots may improve the one reproduction of printers having important dot gain.

  19. Sustainability; Sustentabilidade

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-10-15

    This chapter analyses the production chain of ethanol, considering the impacts on the quality of the air, water supplies, soil occupation and biodiversity, and the efforts for the soil preservation. It is pointed out the activities of the production cycle and use of bio ethanol due to great uncertainties as far the environmental impacts is concerning and that will deserve more attention in future evaluations. At same time, the chapter highlights another activities where the present acknowledge is sufficient to assure the control and/or prediction of consequences of the desired intervention on the environment media to accommodate the sugar and ethanol production expansion. The consideration is not conservative but to promote the sustainable development.

  20. Modeling and simulation of InGaN/GaN quantum dots solar cell

    Science.gov (United States)

    Aissat, A.; Benyettou, F.; Vilcot, J. P.

    2016-07-01

    Currently, quantum dots have attracted attention in the field of optoelectronics, and are used to overcome the limits of a conventional solar cell. Here, an In0.25Ga0.75N/GaN Quantum Dots Solar Cell has been modeled and simulated using Silvaco Atlas. Our results show that the short circuit current increases with the insertion of the InGaN quantum dots inside the intrinsic region of a GaN pin solar cell. In contrary, the open circuit voltage decreases. A relative optimization of the conversion efficiency of 54.77% was achieved comparing a 5-layers In0.25Ga0.75N/GaN quantum dots with pin solar cell. The conversion efficiency begins to decline beyond 5-layers quantum dots introduced. Indium composition of 10 % improves relatively the efficiency about 42.58% and a temperature of 285 K gives better conversion efficiency of 13.14%.

  1. Trajectories of sustainability reporting by MNCs

    NARCIS (Netherlands)

    Kolk, A.

    2010-01-01

    With increasing attention to sustainable business, reporting by Multinational Corporations (MNCs) about the social and environmental dimensions of their activities - alongside their economic impacts - has become rather common. While research has documented sustainability reporting and looked at

  2. Red Dot Basal Cell Carcinoma

    Science.gov (United States)

    2017-01-01

    Red dot basal cell carcinoma, a distinctive morphologic variant of basal cell carcinoma that presents as a small red macule (dot) or papule, is described on a woman’s thigh. A high index of suspicion is necessary to consider the diagnosis since the tumor mimics a telangiectasia or an angioma. PMID:28670359

  3. Functional surface engineering of C-dots for fluorescent biosensing and in vivo bioimaging.

    Science.gov (United States)

    Ding, Changqin; Zhu, Anwei; Tian, Yang

    2014-01-21

    Nanoparticles are promising scaffolds for applications such as imaging, chemical sensors and biosensors, diagnostics, drug delivery, catalysis, energy, photonics, medicine, and more. Surface functionalization of nanoparticles introduces an additional dimension in controlling nanoparticle interfacial properties and provides an effective bridge to connect nanoparticles to biological systems. With fascinating photoluminescence properties, carbon dots (C-dots), carbon-containing nanoparticles that are attracting considerable attention as a new type of quantum dot, are becoming both an important class of imaging probes and a versatile platform for engineering multifunctional nanosensors. In order to transfer C-dots from proof-of-concept studies toward real world applications such as in vivo bioimaging and biosensing, careful design and engineering of C-dot probes is becoming increasingly important. A comprehensive knowledge of how C-dot surfaces with various properties behave is essential for engineering C-dots with useful imaging properties such as high quantum yield, stability, and low toxicity, and with desirable biosensing properties such as high selectivity, sensitivity, and accuracy. Several reviews in recent years have reported preparation methods and properties of C-dots and described their application in biosensors, catalysis, photovoltatic cells, and more. However, no one has yet systematically summarized the surface engineering of C-dots, nor the use of C-dots as fluorescent nanosensors or probes for in vivo imaging in cells, tissues, and living organisms. In this Account, we discuss the major design principles and criteria for engineering the surface functionality of C-dots for biological applications. These criteria include brightness, long-term stability, and good biocompatibility. We review recent developments in designing C-dot surfaces with various functionalities for use as nanosensors or as fluorescent probes with fascinating analytical performance

  4. Attention in schizophrenia and in epileptic psychosis

    Directory of Open Access Journals (Sweden)

    I.C.J Kairalla

    2008-01-01

    Full Text Available The adaptive behavior of human beings is usually supported by rapid monitoring of outstanding events in the environment. Some investigators have suggested that a primary attention deficit might trigger symptoms of schizophrenia. In addition, researchers have long discussed the relationship between schizophrenia and the schizophrenia-like psychosis of epilepsy (SLPE. On the basis of these considerations, the objective of the present study was to investigate attention performance of patients with both disorders. Patient age was 18 to 60 years, and all patients had received formal schooling for at least four years. Patients were excluded if they had any systemic disease with neurologic or psychiatric comorbidity, or a history of brain surgery. The computer-assisted TAVIS-2R test was applied to all patients and to a control group to evaluate and discriminate between selective, alternating and sustained attention. The TAVIS-2R test is divided into three parts: one for selective attention (5 min, the second for alternating attention (5 min, and the third for the evaluation of vigilance or sustained attention (10 min. The same computer software was used for statistical analysis of reaction time, omission errors, and commission errors. The sample consisted of 36 patients with schizophrenia, 28 with interictal SLPE, and 47 healthy controls. The results of the selective attention tests for both patient groups were significantly lower than that for controls. The patients with schizophrenia and SLPE performed differently in the alternating and sustained attention tests: patients with SLPE had alternating attention deficits, whereas patients with schizophrenia showed deficits in sustained attention. These quantitative results confirmed the qualitative clinical observations for both patient groups, that is, that patients with schizophrenia had difficulties in focusing attention, whereas those with epilepsy showed perseveration in attention focus.

  5. Extended attention span training system

    Science.gov (United States)

    Pope, Alan T.; Bogart, Edward H.

    1991-01-01

    Attention Deficit Disorder (ADD) is a behavioral disorder characterized by the inability to sustain attention long enough to perform activities such as schoolwork or organized play. Treatments for this disorder include medication and brainwave biofeedback training. Brainwave biofeedback training systems feed back information to the trainee showing him how well he is producing the brainwave pattern that indicates attention. The Extended Attention Span Training (EAST) system takes the concept a step further by making a video game more difficult as the player's brainwaves indicate that attention is waning. The trainee can succeed at the game only by maintaining an adequate level of attention. The EAST system is a modification of a biocybernetic system that is currently being used to assess the extent to which automated flight management systems maintain pilot engagement. This biocybernetic system is a product of a program aimed at developing methods to evaluate automated flight deck designs for compatibility with human capabilities. The EAST technology can make a contribution in the fields of medical neuropsychology and neurology, where the emphasis is on cautious, conservative treatment of youngsters with attention disorders.

  6. Facilitated preparation of bioconjugatable zwitterionic quantum dots using dual-lipid encapsulation.

    Science.gov (United States)

    Shrake, Robert; Demillo, Violeta G; Ahmadiantehrani, Mojtaba; Zhu, Xiaoshan; Publicover, Nelson G; Hunter, Kenneth W

    2015-01-01

    Zwitterionic quantum dots prepared through incorporated zwitterionic ligands on quantum dot surfaces, are being paid significant attention in biomedical applications because of their excellent colloidal stability across a wide pH and ionic strength range, antifouling surface, good biocompatibility, etc. In this work, we report a dual-lipid encapsulation approach to prepare bioconjugatable zwitterionic quantum dots using amidosulfobetaine-16 lipids, dipalmitoyl-sn-glycero-3-phosphoethanolamine lipids with functional head groups, and CuInS2/ZnS quantum dots in a tetrahydrofuran/methanol/water solvent system with sonication. Amidosulfobetaine-16 is a zwitterionic lipid and dipalmitoyl-sn-glycero-3-phosphoethanolamine, with its functional head, provides bioconjugation capability. Under sonication, tetrahydrofuran/methanol containing amidosulfobetaine-16, dipalmitoyl-sn-glycero-3-phosphoethanolamine, and hydrophobic quantum dots are dispersed in water to form droplets. Highly water-soluble tetrahydrofuran/methanol in droplets is further displaced by water, which induces the lipid self-assembling on hydrophobic surface of quantum dots and thus forms water soluble zwitterionic quantum dots. The prepared zwitterionic quantum dots maintain colloidal stability in aqueous solutions with high salinity and over a wide pH range. They are also able to be conjugated with biomolecules for bioassay with minimal nonspecific binding. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Sustainable nuclear energy dilemma

    Directory of Open Access Journals (Sweden)

    Afgan Naim H.

    2013-01-01

    Full Text Available Sustainable energy development implies the need for the emerging potential energy sources which are not producing adverse effect to the environment. In this respect nuclear energy has gained the complimentary favor to be considered as the potential energy source without degradation of the environment. The sustainability evaluation of the nuclear energy systems has required the special attention to the criteria for the assessment of nuclear energy system before we can make firm justification of the sustainability of nuclear energy systems. In order to demonstrate the sustainability assessment of nuclear energy system this exercise has been devoted to the potential options of nuclear energy development, namely: short term option, medium term option, long term option and classical thermal system option. Criteria with following indicators are introduced in this analysis: nuclear indicator, economic indicator, environment indicator, social indicator... The Sustainability Index is used as the merit for the priority assessment among options under consideration.

  8. Multi-million atom electronic structure calculations for quantum dots

    Science.gov (United States)

    Usman, Muhammad

    Quantum dots grown by self-assembly process are typically constructed by 50,000 to 5,000,000 structural atoms which confine a small, countable number of extra electrons or holes in a space that is comparable in size to the electron wavelength. Under such conditions quantum dots can be interpreted as artificial atoms with the potential to be custom tailored to new functionality. In the past decade or so, these nanostructures have attracted significant experimental and theoretical attention in the field of nanoscience. The new and tunable optical and electrical properties of these artificial atoms have been proposed in a variety of different fields, for example in communication and computing systems, medical and quantum computing applications. Predictive and quantitative modeling and simulation of these structures can help to narrow down the vast design space to a range that is experimentally affordable and move this part of nanoscience to nano-Technology. Modeling of such quantum dots pose a formidable challenge to theoretical physicists because: (1) Strain originating from the lattice mismatch of the materials penetrates deep inside the buffer surrounding the quantum dots and require large scale (multi-million atom) simulations to correctly capture its effect on the electronic structure, (2) The interface roughness, the alloy randomness, and the atomistic granularity require the calculation of electronic structure at the atomistic scale. Most of the current or past theoretical calculations are based on continuum approach such as effective mass approximation or k.p modeling capturing either no or one of the above mentioned effects, thus missing some of the essential physics. The Objectives of this thesis are: (1) to model and simulate the experimental quantum dot topologies at the atomistic scale; (2) to theoretically explore the essential physics i.e. long range strain, linear and quadratic piezoelectricity, interband optical transition strengths, quantum confined

  9. Reappraisal modulates attentional bias to angry faces

    Directory of Open Access Journals (Sweden)

    Shin Ah Kim

    2016-11-01

    Full Text Available Heightened attentional bias to emotional information is one of the main characteristics of disorders related to emotion dysregulation such as anxiety, depression, and substance abuse. Although reappraisal, an emotion regulation strategy, is known to effectively modulate subjective experience of emotions, it remains unknown whether reappraisal can alter attentional biases to emotional information. In the current research, we investigated the influence of instruction-induced state reappraisal (Study 1 and trait reappraisal (Study 2 on attentional biases to happy and angry faces. In Study 1, healthy young women were recruited and randomly assigned to one of the three groups: up-, down-, and no-regulation. Participants were instructed to reappraise their emotions to increase and decrease emotional experience while viewing an emotionally negative film clip. Attentional bias was assessed with a dot-probe task with pictures of angry and happy facial expressions. In Study 2, a separate group of healthy young men and women participated. Participants’ trait reappraisal and suppression as well as state and trait anxiety were assessed. A dot-probe task was completed by all participants. Statistical tests in Study 1 revealed that participants who reappraised to decrease negative emotions while viewing an emotionally negative film clip had reduced attentional bias to subsequently presented angry faces compared to participants who reappraised to increase negative emotions. Multiple regression analyses in Study 2 revealed that trait reappraisal predicted slower orienting toward angry faces, whereas state anxiety predicted slower disengagement from angry faces. Interestingly, trait suppression predicted slower disengagement from happy faces. Taken together, these results suggest that both instruction-induced state reappraisal and trait reappraisal are linked to reduced attentional bias to negative information and contribute to better understanding of how

  10. Investigation of Sustainable Housing Criteria

    OpenAIRE

    roshanfekr Somayeh; Tawil N.M.; Goh N.A.

    2016-01-01

    Recently, much attention has been paid to sustainable development in cities. The quality of human life is directly related to environmental quality. Because many people live in cities as a place of social, economic and cultural relationships, certain issues such as environmental crises, energy, air and noise pollution and traffic jams are some of the factors that can alter the quality of human life. Therefore, in order to improve the quality of human life, attention to sustainable development...

  11. Attentional capture by the onset and offset of motion signals outside the spatial focus of attention.

    Science.gov (United States)

    Kawahara, Jun; Yanase, Kaori; Kitazaki, Michiteru

    2012-11-16

    The present study examined whether participants were able to ignore a task-irrelevant commencement or cessation of optic flow while they were engaging in a letter-identification task, as claimed by adherents of the view that attentional set determines deployment of attention, or whether irrelevant events would capture attention regardless of observers' attentional set, as claimed by adherents of a broad range of views emphasizing the behavioral urgency of stimulus motion. Observers identified a green letter in a central rapid stream of heterogeneously colored nontargets. A completely task-irrelevant optic flow occurred in the periphery. If attentional deployment were governed by a top-down attentional set, the letter identification would be unaffected by the temporal change in the optic flow. The results reflected attentional capture by commencement or cessation of optic flow, which is inconsistent with the top-down view. When the peripheral dots expanded at various speeds before onset of the target, identification was impaired relative to when no motion occurred. Mere commencement or cessation of motion was sufficient to produce the capture effect. Qualitative (commencement or cessation) rather than quantitative changes (acceleration or deceleration) of the motion display were critical for the occurrence of attentional capture. We conclude that salient discontinuities in optic flow induce attentional capture when observers search for a feature in a different stimulus domain, an idea implying a unique role for of expanding global motion in the deployment of visual attention.

  12. Effects of a structured 20-session slow-cortical-potential-based neurofeedback program on attentional performance in children and adolescents with attention-deficit hyperactivity disorder: retrospective analysis of an open-label pilot-approach and 6-month follow-up.

    Science.gov (United States)

    Albrecht, Johanna S; Bubenzer-Busch, Sarah; Gallien, Anne; Knospe, Eva Lotte; Gaber, Tilman J; Zepf, Florian D

    2017-01-01

    The aim of this approach was to conduct a structured electroencephalography-based neurofeedback training program for children and adolescents with attention-deficit hyperactivity disorder (ADHD) using slow cortical potentials with an intensive first (almost daily sessions) and second phase of training (two sessions per week) and to assess aspects of attentional performance. A total of 24 young patients with ADHD participated in the 20-session training program. During phase I of training (2 weeks, 10 sessions), participants were trained on weekdays. During phase II, neurofeedback training occurred twice per week (5 weeks). The patients' inattention problems were measured at three assessment time points before (pre, T0) and after (post, T1) the training and at a 6-month follow-up (T2); the assessments included neuropsychological tests (Alertness and Divided Attention subtests of the Test for Attentional Performance; Sustained Attention Dots and Shifting Attentional Set subtests of the Amsterdam Neuropsychological Test) and questionnaire data (inattention subscales of the so-called Fremdbeurteilungsbogen für Hyperkinetische Störungen and Child Behavior Checklist/4-18 [CBCL/4-18]). All data were analyzed retrospectively. The mean auditive reaction time in a Divided Attention task decreased significantly from T0 to T1 (medium effect), which was persistent over time and also found for a T0-T2 comparison (larger effects). In the Sustained Attention Dots task, the mean reaction time was reduced from T0-T1 and T1-T2 (small effects), whereas in the Shifting Attentional Set task, patients were able to increase the number of trials from T1-T2 and significantly diminished the number of errors (T1-T2 & T0-T2, large effects). First positive but very small effects and preliminary results regarding different parameters of attentional performance were detected in young individuals with ADHD. The limitations of the obtained preliminary data are the rather small sample size, the

  13. Attentional Processing and Teacher Ratings in Hyperactive, Learning Disabled and Normal Boys.

    Science.gov (United States)

    Brown, Ronald T.; Wynne, Martha Ellen

    Sustained attention and inhibitory control of 15 nonhyperactive, learning disabled (LD) boys, 15 hyperactive but not LD boys, and 15 normal boys (11-12 years old) were studied, on teacher ratings of impulse control in the classroom and testing results. Coming to attention, decision making, sustained attention, and attention-concentration were…

  14. Inflexible Minds : Impaired Attention Switching in Recent-Onset Schizophrenia

    NARCIS (Netherlands)

    Smid, Henderikus G. O. M.; Martens, Sander; de Witte, Marc R.; Bruggeman, Richard

    2013-01-01

    Impairment of sustained attention is assumed to be a core cognitive abnormality in schizophrenia. However, this seems inconsistent with a recent hypothesis that in schizophrenia the implementation of selection (i.e., sustained attention) is intact but the control of selection (i.e., switching the

  15. Sustainable Food & Sustainable Economics

    OpenAIRE

    Alvarez, Mavis Dora

    2012-01-01

    Cuba today is immersed in a very intense process of perfecting its agricultural production structures with the goal of making them more efficient and sustainable in their economic administration and in their social and environmental management. Agricultural cooperatives in Cuba have the responsibility of producing on 73% of the country's farmland. Their contributions are decisive to developing agricultural production and to ensuring more and better food for the population, in addition to redu...

  16. The Attention Cascade Model and Attentional Blink

    Science.gov (United States)

    Shih, Shui-I

    2008-01-01

    An attention cascade model is proposed to account for attentional blinks in rapid serial visual presentation (RSVP) of stimuli. Data were collected using single characters in a single RSVP stream at 10 Hz [Shih, S., & Reeves, A. (2007). "Attentional capture in rapid serial visual presentation." "Spatial Vision", 20(4), 301-315], and single words,…

  17. DOT Official County Highway Map

    Data.gov (United States)

    Minnesota Department of Natural Resources — The County Highway Map theme is a scanned and rectified version of the original MnDOT County Highway Map Series. The cultural features on some of these maps may be...

  18. Marvelous applications of quantum dots.

    Science.gov (United States)

    Cheki, M; Moslehi, M; Assadi, M

    2013-05-01

    Nanotechnology is developed to convert research, prevention, and treatment of cancer through the novel diagnostic imaging techniques and therapies. In particular, the imaging nanotechnology has gained substantial momentum in recent years. The main progress in nanotechnology has led to the production of novel fluorescent probes named quantum dots (QDs). Quantum dots develop a revolution in the molecular tagging processes within research, in vivo and in vitro studies. Due to unique physical and chemical features of QD probes, new possible techniques of early cancer detection and therapeutic management are being surveyed. Quantum dots have also dissolved many of the restrictions of organic fluorophores and are a talented option as a research tool. This review addresses on the present status of research, preclinical applications and also future visions of quantum dots.  

  19. PennDOT : fact book

    Science.gov (United States)

    2008-06-01

    PennDOT was created in 1970 when the former : Department of Highways was merged with transportation related : functions from the Departments of Revenue, : Commerce, Community Affairs and Military Affairs. With : an annual budget of about $5.4 billion...

  20. Implementace hry Dots and Boxes

    OpenAIRE

    Balko, Martin

    2010-01-01

    Title: Dots and Boxes implementation Author: Martin Balko Department: Department of Applied Mathematics Supervisor: RNDr. Ondřej Pangrác, Ph.D. Supervisor's email address: Abstract: The presented thesis deals with the analysis of a popular logical game Dots and Boxes and its generalized versions. It focuses on the different methods and algorithms of opponent's artificial intelligence. The result of the work is implementation of the generalized version of this game in w...

  1. Quantum dots in cell biology.

    Science.gov (United States)

    Barroso, Margarida M

    2011-03-01

    Quantum dots are semiconductor nanocrystals that have broad excitation spectra, narrow emission spectra, tunable emission peaks, long fluorescence lifetimes, negligible photobleaching, and ability to be conjugated to proteins, making them excellent probes for bioimaging applications. Here the author reviews the advantages and disadvantages of using quantum dots in bioimaging applications, such as single-particle tracking and fluorescence resonance energy transfer, to study receptor-mediated transport.

  2. Semiconductor quantum dot-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Jianjun Tian

    2013-10-01

    Full Text Available Semiconductor quantum dots (QDs have been drawing great attention recently as a material for solar energy conversion due to their versatile optical and electrical properties. The QD-sensitized solar cell (QDSC is one of the burgeoning semiconductor QD solar cells that shows promising developments for the next generation of solar cells. This article focuses on recent developments in QDSCs, including 1 the effect of quantum confinement on QDSCs, 2 the multiple exciton generation (MEG of QDs, 3 fabrication methods of QDs, and 4 nanocrystalline photoelectrodes for solar cells. We also make suggestions for future research on QDSCs. Although the efficiency of QDSCs is still low, we think there will be major breakthroughs in developing QDSCs in the future.

  3. Solar-Driven Hydrogen Peroxide Production Using Polymer-Supported Carbon Dots as Heterogeneous Catalyst

    Science.gov (United States)

    Gogoi, Satyabrat; Karak, Niranjan

    2017-10-01

    Safe, sustainable, and green production of hydrogen peroxide is an exciting proposition due to the role of hydrogen peroxide as a green oxidant and energy carrier for fuel cells. The current work reports the development of carbon dot-impregnated waterborne hyperbranched polyurethane as a heterogeneous photo-catalyst for solar-driven production of hydrogen peroxide. The results reveal that the carbon dots possess a suitable band-gap of 2.98 eV, which facilitates effective splitting of both water and ethanol under solar irradiation. Inclusion of the carbon dots within the eco-friendly polymeric material ensures their catalytic activity and also provides a facile route for easy catalyst separation, especially from a solubilizing medium. The overall process was performed in accordance with the principles of green chemistry using bio-based precursors and aqueous medium. This work highlights the potential of carbon dots as an effective photo-catalyst.

  4. Stability of quantum dots in live cells

    Science.gov (United States)

    Zhu, Zheng-Jiang; Yeh, Yi-Cheun; Tang, Rui; Yan, Bo; Tamayo, Joshua; Vachet, Richard W.; Rotello, Vincent M.

    2011-12-01

    Quantum dots are highly fluorescent and photostable, making them excellent tools for imaging. When using these quantum dots in cells and animals, however, intracellular biothiols (such as glutathione and cysteine) can degrade the quantum dot monolayer, compromising function. Here, we describe a label-free method to quantify the intracellular stability of monolayers on quantum dot surfaces that couples laser desorption/ionization mass spectrometry with inductively coupled plasma mass spectrometry. Using this new approach we have demonstrated that quantum dot monolayer stability is correlated with both quantum dot particle size and monolayer structure, with appropriate choice of both particle size and ligand structure required for intracellular stability.

  5. Attention bias modification in specific fears: Spiders versus snakes.

    Science.gov (United States)

    Luo, Xijia; Ikani, Nessa; Barth, Anja; Rengers, Lea; Becker, Eni; Rinck, Mike

    2015-12-01

    Attention Bias Modification (ABM) is used to manipulate attention biases in anxiety disorders. It has been successful in reducing attention biases and anxious symptoms in social anxiety and generalized anxiety, but not yet in specific fears and phobias. We designed a new version of the dot-probe training task, aiming to train fearful participants' attention away from or towards pictures of threatening stimuli. Moreover, we studied whether the training also affected participants' avoidance behavior and their physical arousal upon being confronted with a real threat object. In Experiment 1, students with fear of spiders were trained. We found that the attention manipulation was successful, but the training failed to affect behavior or arousal. In Experiment 2, the same procedure was used on snake-fearful students. Again, attention was trained in the expected directions. Moreover, participants whose attention had been trained away from snakes showed lower physiological arousal upon being confronted with a real snake. The study involved healthy students with normal distribution of the fear of spider/snake. Future research with clinical sample could help with determining the generalizability of the current findings. The effect of ABM on specific phobia is still in question. The finding in the present study suggested the possibility to alter attentional bias with a dot-probe task with general positive stimuli and this training could even affect the behavior while encountering a real threat. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. An Eye Tracking Investigation of Attentional Biases towards Affect in Young Children

    Science.gov (United States)

    Burris, Jessica L.; Barry-Anwar, Ryan A.; Rivera, Susan M.

    2017-01-01

    This study examines attentional biases in the presence of angry, happy and neutral faces using a modified eye tracking version of the dot probe task (DPT). Participants were 111 young children between 9 and 48 months. Children passively viewed an affective attention bias task that consisted of a face pairing (neutral paired with either neutral,…

  7. Imaging and Manipulating Energy Transfer Among Quantum Dots at Individual Dot Resolution.

    Science.gov (United States)

    Nguyen, Duc; Nguyen, Huy A; Lyding, Joseph W; Gruebele, Martin

    2017-06-27

    Many processes of interest in quantum dots involve charge or energy transfer from one dot to another. Energy transfer in films of quantum dots as well as between linked quantum dots has been demonstrated by luminescence shift, and the ultrafast time-dependence of energy transfer processes has been resolved. Bandgap variation among dots (energy disorder) and dot separation are known to play an important role in how energy diffuses. Thus, it would be very useful if energy transfer could be visualized directly on a dot-by-dot basis among small clusters or within films of quantum dots. To that effect, we report single molecule optical absorption detected by scanning tunneling microscopy (SMA-STM) to image energy pooling from donor into acceptor dots on a dot-by-dot basis. We show that we can manipulate groups of quantum dots by pruning away the dominant acceptor dot, and switching the energy transfer path to a different acceptor dot. Our experimental data agrees well with a simple Monte Carlo lattice model of energy transfer, similar to models in the literature, in which excitation energy is transferred preferentially from dots with a larger bandgap to dots with a smaller bandgap.

  8. Harnessing Sun’s Energy with Quantum Dots Based Next Generation Solar Cell

    Science.gov (United States)

    Halim, Mohammad A.

    2012-01-01

    Our energy consumption relies heavily on the three components of fossil fuels (oil, natural gas and coal) and nearly 83% of our current energy is consumed from those sources. The use of fossil fuels, however, has been viewed as a major environmental threat because of their substantial contribution to greenhouse gases which are responsible for increasing the global average temperature. Last four decades, scientists have been searching for alternative sources of energy which need to be environmentally clean, efficient, cost-effective, renewable, and sustainable. One of the promising sustainable sources of energy can be achieved by harnessing sun energy through silicon wafer, organic polymer, inorganic dye, and quantum dots based solar cells. Among them, quantum dots have an exceptional property in that they can excite multiple electrons using only one photon. These dots can easily be synthesized, processed in solution, and incorporated into solar cell application. Interestingly, the quantum dots solar cells can exceed the Shockley-Queisser limit; however, it is a great challenge for other solar cell materials to exceed the limit. Theoretically, the quantum dots solar cell can boost the power conversion efficiency up to 66% and even higher to 80%. Moreover, in changing the size of the quantum dots one can utilize the Sun’s broad spectrum of visible and infrared ranges. This review briefly overviews the present performance of different materials-based solar cells including silicon wafer, dye-sensitized, and organic solar cells. In addition, recent advances of the quantum dots based solar cells which utilize cadmium sulfide/selenide, lead sulfide/selenide, and new carbon dots as light harvesting materials has been reviewed. A future outlook is sketched as to how one could improve the efficiency up to 10% from the current highest efficiency of 6.6%. PMID:28348320

  9. Harnessing Sun's Energy with Quantum Dots Based Next Generation Solar Cell.

    Science.gov (United States)

    Halim, Mohammad A

    2012-12-27

    Our energy consumption relies heavily on the three components of fossil fuels (oil, natural gas and coal) and nearly 83% of our current energy is consumed from those sources. The use of fossil fuels, however, has been viewed as a major environmental threat because of their substantial contribution to greenhouse gases which are responsible for increasing the global average temperature. Last four decades, scientists have been searching for alternative sources of energy which need to be environmentally clean, efficient, cost-effective, renewable, and sustainable. One of the promising sustainable sources of energy can be achieved by harnessing sun energy through silicon wafer, organic polymer, inorganic dye, and quantum dots based solar cells. Among them, quantum dots have an exceptional property in that they can excite multiple electrons using only one photon. These dots can easily be synthesized, processed in solution, and incorporated into solar cell application. Interestingly, the quantum dots solar cells can exceed the Shockley-Queisser limit; however, it is a great challenge for other solar cell materials to exceed the limit. Theoretically, the quantum dots solar cell can boost the power conversion efficiency up to 66% and even higher to 80%. Moreover, in changing the size of the quantum dots one can utilize the Sun's broad spectrum of visible and infrared ranges. This review briefly overviews the present performance of different materials-based solar cells including silicon wafer, dye-sensitized, and organic solar cells. In addition, recent advances of the quantum dots based solar cells which utilize cadmium sulfide/selenide, lead sulfide/selenide, and new carbon dots as light harvesting materials has been reviewed. A future outlook is sketched as to how one could improve the efficiency up to 10% from the current highest efficiency of 6.6%.

  10. Harnessing Sun’s Energy with Quantum Dots Based Next Generation Solar Cell

    Directory of Open Access Journals (Sweden)

    Mohammad A. Halim

    2012-12-01

    Full Text Available Our energy consumption relies heavily on the three components of fossil fuels (oil, natural gas and coal and nearly 83% of our current energy is consumed from those sources. The use of fossil fuels, however, has been viewed as a major environmental threat because of their substantial contribution to greenhouse gases which are responsible for increasing the global average temperature. Last four decades, scientists have been searching for alternative sources of energy which need to be environmentally clean, efficient, cost-effective, renewable, and sustainable. One of the promising sustainable sources of energy can be achieved by harnessing sun energy through silicon wafer, organic polymer, inorganic dye, and quantum dots based solar cells. Among them, quantum dots have an exceptional property in that they can excite multiple electrons using only one photon. These dots can easily be synthesized, processed in solution, and incorporated into solar cell application. Interestingly, the quantum dots solar cells can exceed the Shockley-Queisser limit; however, it is a great challenge for other solar cell materials to exceed the limit. Theoretically, the quantum dots solar cell can boost the power conversion efficiency up to 66% and even higher to 80%. Moreover, in changing the size of the quantum dots one can utilize the Sun’s broad spectrum of visible and infrared ranges. This review briefly overviews the present performance of different materials-based solar cells including silicon wafer, dye-sensitized, and organic solar cells. In addition, recent advances of the quantum dots based solar cells which utilize cadmium sulfide/selenide, lead sulfide/selenide, and new carbon dots as light harvesting materials has been reviewed. A future outlook is sketched as to how one could improve the efficiency up to 10% from the current highest efficiency of 6.6%.

  11. Mental training enhances attentional stability: neural and behavioral evidence

    NARCIS (Netherlands)

    Lutz, A.; Slagter, H.A.; Rawlings, N.B.; Francis, A.D.; Greischar, L.L.; Davidson, R.J.

    2009-01-01

    The capacity to stabilize the content of attention over time varies among individuals, and its impairment is a hallmark of several mental illnesses. Impairments in sustained attention in patients with attention disorders have been associated with increased trial-to-trial variability in reaction time

  12. Understanding and Working with Attention Deficit Disorder Students

    Science.gov (United States)

    Buttery, Thomas J.

    2009-01-01

    From a holistic perspective the term attention refers to a student's capacity to focus, direct and sustain their attention on a particular stimulus within their environment for a significant period of time. The development of students' attention spans develops progressively from the time they enter school. From the beginning some students have…

  13. Attentional retraining can reduce chocolate consumption.

    Science.gov (United States)

    Kemps, Eva; Tiggemann, Marika; Orr, Jenna; Grear, Justine

    2014-03-01

    There is emerging evidence that attentional biases are related to the consumption of substances such as alcohol and tobacco, and that attentional bias modification can reduce unwanted consumption of these substances. We present evidence for the first time to our knowledge that the same logical argument applies in the food and eating domain. We conducted two experiments that used a modified dot probe paradigm to train undergraduate women to direct their attention toward ("attend") or away from ("avoid") food cues (i.e., pictures of chocolate). In Experiment 1, attentional bias for chocolate cues increased in the "attend" group, and decreased in the "avoid" group. Experiment 2 showed that these training effects generalized to novel, previously unseen chocolate pictures. Importantly, attentional retraining affected chocolate consumption and craving. In both experiments, participants in the "avoid" group ate less chocolate in a so-called taste test than did those in the "attend" group. In addition, in Experiment 2, but not in Experiment 1, the "attend" group reported stronger chocolate cravings following training, whereas the "avoid" group reported less intense cravings. The results support predictions of cognitive-motivational models of craving and consumption that attentional biases play a causal role in consumption behavior. Furthermore, they present a promising avenue for tackling unwanted food cravings and (over)eating. © 2013 American Psychological Association

  14. Partnership for Sustainable Communities: Five Years of Learning from Communities and Coordinating Federal Investments

    Science.gov (United States)

    This report commemorating the fifth anniversary of the HUD-DOT-EPA Partnership for Sustainable Communities shows how the three agencies are changing their policies and removing barriers to help communities.

  15. Backward Masked Snakes and Guns Modulate Spatial Attention

    Directory of Open Access Journals (Sweden)

    Joshua M. Carlson

    2009-10-01

    Full Text Available Fearful faces are important social cues that alert others of potential threat. Even backward masked fearful faces facilitate spatial attention. However, visual stimuli other than fearful faces can signal potential threat. Indeed, unmasked snakes and spiders modulate spatial attention. Yet, it is unclear if the rapid threat-related facilitation of spatial attention to backward masked stimuli is elicited by non-face threat cues. Evolutionary theories claim that phylogenetic threats (i.e. snakes and spiders should preferentially elicit an automatic fear response, but it is untested as to whether this response extends to enhancements in spatial attention under restricted processing conditions. Thirty individuals completed a backward masking dot-probe task with both evolutionary relevant and irrelevant threat cues. The results suggest that backward masked visual fear stimuli modulate spatial attention. Both evolutionary relevant (snake and irrelevant (gun threat cues facilitated spatial attention.

  16. Inter-dot coupling effects on transport through correlated parallel ...

    Indian Academy of Sciences (India)

    The effect of inter-dot tunnelling on transport properties has been explored. Results, in intermediate inter-dot coupling regime show signatures of merger of two dots to form a single composite dot and in strong coupling regime the behaviour of the system resembles the two decoupled dots. Keywords. Coupled quantum dots ...

  17. Transport through graphene quantum dots

    Science.gov (United States)

    Güttinger, J.; Molitor, F.; Stampfer, C.; Schnez, S.; Jacobsen, A.; Dröscher, S.; Ihn, T.; Ensslin, K.

    2012-12-01

    We review transport experiments on graphene quantum dots and narrow graphene constrictions. In a quantum dot, electrons are confined in all lateral dimensions, offering the possibility for detailed investigation and controlled manipulation of individual quantum systems. The recently isolated two-dimensional carbon allotrope graphene is an interesting host to study quantum phenomena, due to its novel electronic properties and the expected weak interaction of the electron spin with the material. Graphene quantum dots are fabricated by etching mono-layer flakes into small islands (diameter 60-350 nm) with narrow connections to contacts (width 20-75 nm), serving as tunneling barriers for transport spectroscopy. Electron confinement in graphene quantum dots is observed by measuring Coulomb blockade and transport through excited states, a manifestation of quantum confinement. Measurements in a magnetic field perpendicular to the sample plane allowed to identify the regime with only a few charge carriers in the dot (electron-hole transition), and the crossover to the formation of the graphene specific zero-energy Landau level at high fields. After rotation of the sample into parallel magnetic field orientation, Zeeman spin splitting with a g-factor of g ≈ 2 is measured. The filling sequence of subsequent spin states is similar to what was found in GaAs and related to the non-negligible influence of exchange interactions among the electrons.

  18. Sustainable agriculture

    National Research Council Canada - National Science Library

    Lichtfouse, Eric

    2009-01-01

    ... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 9 Part I CLIMATE CHANGE Soils and Sustainable Agriculture: A Review : : : : : : : : : : : : : : : : : : : : : : : : : : Rattan Lal 15 Soils and Food Sufficiency...

  19. Effect of Attention Training on Attention Bias Variability and PTSD Symptoms: Randomized Controlled Trials in Israeli and U.S. Combat Veterans.

    Science.gov (United States)

    Badura-Brack, Amy S; Naim, Reut; Ryan, Tara J; Levy, Ofir; Abend, Rany; Khanna, Maya M; McDermott, Timothy J; Pine, Daniel S; Bar-Haim, Yair

    2015-12-01

    Attention allocation to threat is perturbed in patients with posttraumatic stress disorder (PTSD), with some studies indicating excess attention to threat and others indicating fluctuations between threat vigilance and threat avoidance. The authors tested the efficacy of two alternative computerized protocols, attention bias modification and attention control training, for rectifying threat attendance patterns and reducing PTSD symptoms. Two randomized controlled trials compared the efficacy of attention bias modification and attention control training for PTSD: one in Israel Defense Forces veterans and one in U.S. military veterans. Both utilized variants of the dot-probe task, with attention bias modification designed to shift attention away from threat and attention control training balancing attention allocation between threat and neutral stimuli. PTSD symptoms, attention bias, and attention bias variability were measured before and after treatment. Both studies indicated significant symptom improvement after treatment, favoring attention control training. Additionally, both studies found that attention control training, but not attention bias modification, significantly reduced attention bias variability. Finally, a combined analysis of the two samples suggested that reductions in attention bias variability partially mediated improvement in PTSD symptoms. Attention control training may address aberrant fluctuations in attention allocation in PTSD, thereby reducing PTSD symptoms. Further study of treatment efficacy and its underlying neurocognitive mechanisms is warranted.

  20. Sustainable Marketing

    NARCIS (Netherlands)

    Dam, van Y.K.

    2017-01-01

    In this article, three different conceptions of sustainable marketing are discussed and compared. These different conceptions are referred to as social, green, and critical sustainable marketing. Social sustainable marketing follows the logic of demand-driven marketing management and places the

  1. Applications of quantum dots with upconverting luminescence in bioimaging.

    Science.gov (United States)

    Chen, Yunyun; Liang, Hong

    2014-06-05

    Quantum dots (QDs) have attracted great attention in recent years due to their promising applications in bioimaging. Compared with traditional ultraviolet excitation of QDs, near-infrared laser (NIR) excitation has many advantages, such as being less harmful, little blinking effects, zero autofluorescence and deep penetration in tissue. Composing QDs with upconverting properties is promising to enable NIR excitation. This article provides a review of QDs with upconverting luminescence and their applications in bioimaging. Based on the mechanisms of luminescence, discussion will be divided into four groups: nanoheterostructures/mixtures of QDs and upconverting nanoparticles, graphene quantum dots, lanthanide-doped QDs, and double QDs. The content includes synthetic routes, upconverting luminescence properties, and their applications in bioimaging. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Attentional bias training in girls at risk for depression.

    Science.gov (United States)

    LeMoult, Joelle; Joormann, Jutta; Kircanski, Katharina; Gotlib, Ian H

    2016-11-01

    This study examined, for the first time, whether attentional biases can be modified in adolescents at risk for depression. The final sample consisted of 41 girls at familial risk for depression, who were randomly assigned to receive six sessions (864 trials) of real or sham attention bias training [Real attentional bias training (ABT) vs. Sham ABT]. Participants who received Real ABT completed a modified dot-probe task designed to train attention toward positive and away from negative facial expressions; in contrast, girls who received Sham ABT completed the standard dot-probe task. Attentional biases, self-reported mood, and psychophysiological responses to stress were measured at pre- and post-training assessments. As expected, girls who received Real ABT, but not those who received Sham ABT, exhibited significant increases from pre- to post-training in their attention toward happy faces and away from sad faces. Moreover, adolescents who received Real ABT were buffered against the negative outcomes experienced by adolescents who received Sham ABT. Specifically, only adolescents who received Sham ABT experienced an increase in negative mood and a pre- to post-training increase in heart rate in anticipation of the stressor. The current findings provide the first experimental evidence that attentional biases can be modified in youth at risk for depression and further suggest that ABT modulates the heightened response to stress that is otherwise experienced by high-risk adolescents. © 2016 Association for Child and Adolescent Mental Health.

  3. Decoding covert shifts of attention induced by ambiguous visuospatial cues

    Directory of Open Access Journals (Sweden)

    Romain eTrachel

    2015-06-01

    Full Text Available Simple and unambiguous visual cues (e.g. an arrow can be used to trigger covert shifts of visual attention away from the center of gaze. The processing of visual stimuli is enhanced at the attended location. Covert shifts of attention modulate the power of cerebral oscillations in the alpha band over parietal and occipital regions. These modulations are sufficiently robust to be decoded on a single trial basis from electro-encephalography (EEG signals. It is often assumed that covert attention shifts are under voluntary control, and also occur in more natural and complex environments, but there is no direct evidence to support this assumption. We address this important issue by using random-dot stimuli to cue one of two opposite locations, where a visual target is presented. We contrast two conditions in which the random-dot motion is either predictive of the target location or contains ambiguous information. Behavioral results show attention shifts in anticipation of the visual target, in both conditions. In addition, these attention shifts involve similar neural sources, and the EEG can be decoded on a single trial basis. These results shed a new light on the behavioral and neural correlates of visuospatial attention, with implications for Brain-Computer Interfaces (BCI based on covert attention shifts.

  4. Ultrafast spectroscopy of quantum dots

    CERN Document Server

    Foo, E

    2001-01-01

    exchange-correlation interactions among the confined carriers inside the dots are suggested to be responsible. A density functional calculation for BGR of the ground state transition shows good agreement with our experimental results, especially in the high dot occupancy regime. Many-particle state scattering gives rise to large homogeneous spectral broadening of the PL peaks, from which an intradot relaxation time approx 300 fs is estimated. This observation supports the results obtained by direct excitation of carriers within the QDs. Femtosecond time-resolved photoluminescence measured by frequency up-conversion has been used to investigate carrier dynamics in InAs/GaAs self-assembled quantum dots (QDs). Our results reveal ultrafast carrier relaxation and sequential state filling. Carrier relaxation is proposed to occur by Auger-type processes, and the sequential state filling suggests that intradot relaxation is much faster than carrier capture from the InAs wetting layer. Measurements obtained by direct ...

  5. Quantum-dot emitters in photonic nanostructures

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Stobbe, Søren; Lodahl, Peter

    2010-01-01

    The spontaneous emission from self-assembled semiconductor quantum dots is strongly influenced by the environment in which they are placed. This can be used to determine fundamental optical properties of the quantum dots as well as to manipulate and control the quantum-dot emission itself....

  6. Mood, eating behaviour and attention.

    Science.gov (United States)

    Williams, J M G; Healy, H; Eade, J; Windle, G; Cowen, P J; Green, M W; Durlach, P

    2002-04-01

    Obesity is a growing health problem, but most people find dieting unsuccessful. Three studies examine possible reasons for the difficulty and the extent to which dieting-related reductions in cognitive function are associated with mood and well-being. In Study One, 49 female dieters were compared with a control group of 31 matched non-dieters on measures of well-being, mood, eating behaviour (Dutch Eating Behaviour Questionnaire), and attention. Study Two examined two measures of restraint to examine why previous studies find high restrainers are prone to react to emotion. Study Three experimentally manipulated mood using music and the standard Velten Induction Procedure to examine attention in restrainers and emotional eaters. Dieting was found to be associated with deficits in sustained attention. This finding was further supported by the demonstration of a significant impairment in performance following a negative mood induction in high emotional eaters whereas high restrainers were relatively unaffected by the mood challenge. We suggest that different aspects of eating behaviour have dissociable effects on cognitive-affective function. Trait tendencies to restrained eating are associated with attentional deficits, but are not further affected by mood disruption. It is the long-term tendency to eat when emotional that combines with current emotional state to trigger cognitive deficits.

  7. Photo-stability of CsPbBr3 perovskite quantum dots for optoelectronic application

    NARCIS (Netherlands)

    Chen, Junsheng; Liu, Dongzhou; Al-Marri, Mohammed J.; Nuuttila, Lauri; Lehtivuori, Heli; Zheng, Kaibo

    Due to their superior photoluminescence (PL) quantum yield (QY) and tunable optical band gap, all-inorganic CsPbBr3 perovskite quantum dots (QDs) have attracted intensive attention for the application in solar cells, light emitting diodes (LED), photodetectors and laser devices. In this scenario,

  8. Solid-phase synthesis of highly fluorescent nitrogen-doped carbon dots for sensitive and selective probing ferric ions in living cells.

    Science.gov (United States)

    Zhang, Haijuan; Chen, Yonglei; Liang, Meijuan; Xu, Laifang; Qi, Shengda; Chen, Hongli; Chen, Xingguo

    2014-10-07

    Carbon quantum dots (C-Dots) have drawn extensive attention in recent years due to their stable physicochemical and photochemical properties. However, the development of nitrogen-doped carbon quantum dots (N-doped C-Dots) is still on its early stage. In this paper, a facile and high-output solid-phase synthesis approach was proposed for the fabrication of N-doped, highly fluorescent carbon quantum dots. The obtained N-doped C-Dots exhibited a strong blue emission with an absolute quantum yield (QY) of up to 31%, owing to fluorescence enhancement effect of introduced N atoms into carbon dots. The strong coordination of oxygen-rich groups on N-doped C-Dots to Fe(3+) caused fluorescence quenching via nonradiative electron-transfer, leading to the quantitative detection of Fe(3+). The probe exhibited a wide linear response concentration range (0.01-500 μM) to Fe(3+) with a detection limit of 2.5 nM. Significantly, the N-doped C-Dots possess negligible cytotoxicity, excellent biocompatibility, and high photostability. All these features are favorable for label-free monitoring of Fe(3+) in complex biological samples. It was then successfully applied for the fluorescence imaging of intracellular Fe(3+). As an efficient chemosensor, the N-doped C-Dots hold great promise to broaden applications in biological systems.

  9. Spin storage in quantum dot ensembles and single quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Dominik

    2009-10-15

    This thesis deals with the investigation of spin relaxation of electrons and holes in small ensembles of self-assembled quantum dots using optical techniques. Furthermore, a method to detect the spin orientation in a single quantum dot was developed in the framework of this thesis. A spin storage device was used to optically generate oriented electron spins in small frequency selected quantum dot ensembles using circularly polarized optical excitation. The spin orientation can be determined by the polarization of the time delayed electroluminescence signal generated by the device after a continuously variable storage time. The degree of spin polarized initialization was found to be limited to 0.6 at high magnetic fields, where anisotropic effects are compensated. The spin relaxation was directly measured as a function of magnetic field, lattice temperature and s-shell transition energy of the quantum dot by varying the spin storage time up to 30 ms. Very long spin lifetimes are obtained with a lower limit of T{sub 1}=20 ms at B=4 T and T=1 K. A strong magnetic field dependence T{sub 1}{proportional_to}B{sup -5} has been observed for low temperatures of T=1 K which weakens as the temperature is increased. In addition, the temperature dependence has been determined with T{sub 1}{proportional_to}T{sup -1}. The characteristic dependencies on magnetic field and temperature lead to the identification of the spin relaxation mechanism, which is governed by spin-orbit coupling and mediated by single phonon scattering. This finding is qualitatively supported by the energy dependent measurements. The investigations were extended to a modified device design that enabled studying the spin relaxation dynamics of heavy holes in self-assembled quantum dots. The measurements show a polarization memory effect for holes with up to 0.1 degree of polarization. Furthermore, investigations of the time dynamics of the hole spin relaxation reveal surprisingly long lifetimes T{sub 1}{sup h

  10. One-step synthesis of photoluminescent carbon dots with excitation-independent emission for selective bioimaging and gene delivery.

    Science.gov (United States)

    Yang, Xudong; Wang, Yang; Shen, Xiran; Su, Chunyan; Yang, Jinghua; Piao, Mingjun; Jia, Fei; Gao, Guanghui; Zhang, Long; Lin, Quan

    2017-04-15

    Photoluminescent carbon dots (C-dots), as new members of the quantum sized carbon analogues have attracted significant attention due to their unique size, less toxicity, good compatibility and relatively easy surface modification. In this work, we report a simple, low-cost and one-step hydrothermal carbonization approach to synthesize the positively charged C-dots using PEI and FA. From the photoluminescence (PL) measurements, the as-prepared C-dots exhibit good stability and intense PL with the high quantum yield (QY) at Ca. 42%. Significantly, The as-prepared C-dots integrate the advantages of C-dots and PEI: the presence of C-dots can effectively decrease the cytotoxicity of PEI, the C-dots can be applied in biological system for selective imaging of folate receptor (FR)-positive cancerous cells from normal cells, while the cationic PEI with positive charges can make them link to plasmid DNA and efficiently transfect the therapeutic plasmid into cells. Therefore, the as-prepared with the facile synthesis method can be a promising photoluminescent probe for cancer diagnosis and gene therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Education for Sustainability through a Photography Competition

    OpenAIRE

    Rowena Scott

    2014-01-01

    This article describes the development and history of a sustainability photography competition. From its simple beginnings as an environmental officer’s idea, an environmental sustainability photography competition began in just one university. Now hosted by Australasian Campuses Towards Sustainability (ACTS), finalist entries are viewed on a public website gaining international attention. A purpose of this article is to demonstrate the diversity of views of sustainability by displaying the w...

  12. Effects of Methylphenidate on Attention in ADHD

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-02-01

    Full Text Available In a randomized, double-blind, placebo-controlled study of 60 children aged 8-12 years with ADHD treated with two doses of methylphenidate (MPH, 0.25 and 0.5 mg/kg, and placebo, a linear improvement was obtained at both doses in alertness and focused and sustained attention.

  13. Hyperdense dots mimicking microcalcifications : Mammographic findings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam Hyeon; Park, Jeong Mi; Goo, Hyun Woo; Bang, Sun Woo [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    1996-12-01

    To differentiate fine hyperdense dots mimicking microcalcifications from true microcalcifications on mammography. Mammograms showing hyperdense dots in ten patients (mean age, 59 years) were evaluated. Two radiologists were asked to differentiate with the naked eye the hyperdense dots seen on ten mammograms and proven microcalcifications seen on ten mammograms. Densitometry was also performed for all lesions and the contrast index was calculated. The shape and distribution of the hyperdense dots were evaluated and enquires were made regarding any history of breast disease and corresponding treatment. Biopsies were performed for two patients with hyperdense dots. Two radiologists made correct diagnoses in 19/20 cases(95%). The contrast index was 0.10-0.88 (mean 0.58) for hyperdense dots and 0.02-0.45 (mean 0.17) for true microcalcifications. The hyperdense dots were finer and homogeneously rounder than the microcalcifications. Distribution of the hyperdense dots was more superficial in subcutaneous fat (seven cases) and subareolar area (six cases). All ten patients with hyperdense dots had history of mastitis and abscesses and had been treated by open drainage (six cases) and/or folk remedy (four cases). In eight patients, herb patches had been attached. Biopsies of hyperdense dots did not show any microcalcification or evidence of malignancy. These hyperdense dots were seen mainly in older patients. Their characteristic density, shape, distribution and clinical history makes differential diagnosis from true microcalcifications easy and could reduce unnecessary diagnostic procedures such as surgical biopsy.

  14. Optophononics with Coupled Quantum Dots

    Science.gov (United States)

    2014-02-18

    single InAs/GaAs quantum dots. Phys. Rev. B 68, 233301 (2003). 9. Bennemann, K.-H. & Ketterson, J. B. (eds), Superconductivity : Conventional and...superlattices. Science 338, 935–939 (2012). 17. Kim, J.-H. et al. Coherent phonons in carbon nanotubes and graphene . Chem. Phys. 413, 55–80 (2013). 18

  15. DOT strategies versus orbiter strategies

    NARCIS (Netherlands)

    Rutten, R.J.

    2001-01-01

    The Dutch Open Telescope is a high-resolution solar imager coming on-line at La Palma. The definition of the DOT science niche, strategies, and requirements resemble Solar Orbiter considerations and deliberations. I discuss the latter in the light of the former, and claim that multi-line observation

  16. Luminescent Surface Quaternized Carbon Dots

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-10

    Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.

  17. Polymer-coated quantum dots

    NARCIS (Netherlands)

    Tomczak, N.; Liu, Rongrong; Vancso, Gyula J.

    2013-01-01

    Quantum Dots (QDs) are semiconductor nanocrystals with distinct photophysical properties finding applications in biology, biosensing, and optoelectronics. Polymeric coatings of QDs are used primarily to provide long-term colloidal stability to QDs dispersed in solutions and also as a source of

  18. Nuclear Spins in Quantum Dots

    NARCIS (Netherlands)

    Erlingsson, S.I.

    2003-01-01

    The main theme of this thesis is the hyperfine interaction between the many lattice nuclear spins and electron spins localized in GaAs quantum dots. This interaction is an intrinsic property of the material. Despite the fact that this interaction is rather weak, it can, as shown in this thesis,

  19. Silicon quantum dots: surface matters

    NARCIS (Netherlands)

    Dohnalová, K.; Gregorkiewicz, T.; Kůsová, K.

    2014-01-01

    Silicon quantum dots (SiQDs) hold great promise for many future technologies. Silicon is already at the core of photovoltaics and microelectronics, and SiQDs are capable of efficient light emission and amplification. This is crucial for the development of the next technological frontiers—silicon

  20. Attention Mosaics: Studies of Organizational Attention

    OpenAIRE

    Carvalho de Mesquita Ferreira, Luciana

    2010-01-01

    textabstractOrganizational studies emphasizing the role of attention in organizational behavior depart from the idea that organizations, like individuals, have limited capacity to attend to environmental stimuli. The bounded capacity of the organizations to respond to stimuli is conditioned by the limited cognitions of individuals and by the limited capability of organizations to distribute, coordinate and integrate those cognitions. The cross-level nature of organizational attention, its dua...

  1. Attending to Threat: Race-based Patterns of Selective Attention.

    Science.gov (United States)

    Trawalter, Sophie; Todd, Andrew R; Baird, Abigail A; Richeson, Jennifer A

    2008-09-01

    The present research investigated the extent to which the stereotype that young Black men are threatening and dangerous has become so robust and ingrained in the collective American unconscious that Black men now capture attention, much like evolved threats such as spiders and snakes. Specifically, using a dot-probe detection paradigm, White participants revealed biased attention toward Black faces relative to White faces (Study 1). Because the faces were presented only briefly (30-ms), the bias is thought to reflect the early engagement of attention. The attentional bias was eliminated, however, when the faces displayed averted eye-gaze (Study 2). That is, when the threat communicated by the Black faces was attenuated by a relevant, competing socio-emotional cue- in this case, averted eye-gaze-they no longer captured perceivers' attention. Broader implications for social cognition, as well as public policies that reify these prevailing perceptions of young Black men are discussed.

  2. Working memory load moderates late attentional bias in social anxiety.

    Science.gov (United States)

    Judah, Matt R; Grant, DeMond M; Lechner, William V; Mills, Adam C

    2013-01-01

    The vigilance-avoidance hypothesis suggests that socially anxious individuals attempt to detect signs that they are being evaluated (vigilance) and subsequently direct attention away from such stimuli (avoidance). Although extensive evidence supports vigilance, data concerning subsequent avoidance is equivocal. Drawing from models of attention, the current study hypothesised that working memory load moderates late attentional bias in social anxiety such that avoidance occurs if working memory load is low, and difficulty disengaging attention occurs if working memory load is high. Forty-one undergraduates (19 socially anxious; 22 non-anxious controls) completed a dot-probe task with emotional (happy and disgust) and neutral facial expressions and a concurrent n-back task. Results supported the hypothesis such that socially anxious subjects demonstrated avoidance of disgust faces when working memory load was absent, but had difficulty disengaging attention during high working memory load. Theoretical implications and directions for future research are discussed.

  3. Mechanisms of Perceptual Attention

    National Research Council Canada - National Science Library

    Dosher, Barbara

    2000-01-01

    .... Attention may affect the perceived clarity of visual displays and improve performance. In this project, a powerful external noise method was developed to identify and characterize the effect of attention on perceptual performance in visual tasks...

  4. Mechanism of Perceptual Attention

    National Research Council Canada - National Science Library

    Lu, Zhong-Lin

    2000-01-01

    .... Attention may affect the perceived clarity of visual displays and improve performance. In this project, a powerful external noise method was developed to identify and characterize the effect of attention on perceptual performance in visual tasks...

  5. Sustainable Disruptions

    DEFF Research Database (Denmark)

    Friis, Silje Alberthe Kamille; Kjær, Lykke Bloch

    2016-01-01

    Since 2012 the Sustainable Disruptions (SD) project at the Laboratory for Sustainability at Design School Kolding (DK) has developed and tested a set of design thinking tools, specifically targeting the barriers to economically, socially, and environmentally sustainable business development....... The tools have been applied in practice in collaboration with 11 small and medium sized companies (SMEs). The study investigates these approaches to further understand how design thinking can contribute to sustainable transition in a business context. The study and the findings are relevant to organizations...... invested in the issue of sustainable business development, in particular the leaders and employees of SMEs, but also to design education seeking new ways to consciously handle and teach the complexity inherent in sustainable transformation. Findings indicate that the SD design thinking approach contributes...

  6. Current thinking on contemporary careers: the key roles of sustainable HRM and sustainability of careers

    NARCIS (Netherlands)

    Vos, A. de; Heijden, B.I.J.M. van der

    2017-01-01

    This paper approaches the sustainability of careers, departing from contemporary views on sustainable Human Resource Management (HRM) and key concepts in the current career literature. Recently, the notion of sustainable careers has gained attention as a key perspective on contemporary careers and

  7. Attention Competition with Advertisement

    OpenAIRE

    Cetin, Uzay; Bingol, Haluk O.

    2012-01-01

    In the new digital age, information is available in large quantities. Since information consumes primarily the attention of its recipients, the scarcity of attention is becoming the main limiting factor. In this study, we investigate the impact of advertisement pressure on a cultural market where consumers have a limited attention capacity. A model of competition for attention is developed and investigated analytically and by simulation. Advertisement is found to be much more effective when a...

  8. Computational sustainability

    CERN Document Server

    Kersting, Kristian; Morik, Katharina

    2016-01-01

    The book at hand gives an overview of the state of the art research in Computational Sustainability as well as case studies of different application scenarios. This covers topics such as renewable energy supply, energy storage and e-mobility, efficiency in data centers and networks, sustainable food and water supply, sustainable health, industrial production and quality, etc. The book describes computational methods and possible application scenarios.

  9. Sustainable transformation

    DEFF Research Database (Denmark)

    Andersen, Nicolai Bo

    This paper is about sustainable transformation with a particular focus on listed buildings. It is based on the notion that sustainability is not just a question of energy conditions, but also about the building being robust. Robust architecture means that the building can be maintained and rebuilt...... theoretical lenses. It is proposed that three parameters concerning the ꞌtransformabilityꞌ of the building can contribute to a more nuanced understanding of sustainable transformation: technical aspects, programmatic requirements and narrative value. It is proposed that the concept of ꞌsustainable...

  10. The effect of different stimulus attributes on the attentional performance of children with attention deficit/hyperactivity disorder and dyslexia.

    Science.gov (United States)

    Wang, Li-Chih; Tsai, Huang-Ju; Yang, Hsien-Ming

    2013-11-01

    While teachers have traditionally used the interesting objects to increase student attention in the classroom, evidence supporting the effectiveness of this method is lacking. The present study investigated the influence of different stimulus attributes for typical developing students and for students with attention deficit/hyperactivity disorder (ADHD) and dyslexia. Thirty children with ADHD, 30 children with dyslexia, and 30 typical developing students were tested using a measuring tool that was constructed by the authors to assess their sustained attention and selective attention on the geometric-figure assessment and the interesting-figure assessment. The geometric-figure assessment included a square, circle, trapezium, and triangle; and the interesting-figure assessment included a house, cat, hand, and tree. While the typical developing group showed better selective attention on the geometric-figure assessment, there was no difference between the dyslexic group and the ADHD group with respect to selective attention. Furthermore, the typical developing and dyslexic groups did not differ in the geometric-figure assessment in sustained attention and were both better in this area than the ADHD group. In the interesting-figure assessment, the typical developing and dyslexic groups performed similarly in sustained attention, but selective attention of the dyslexic group improved more than the ADHD group, similar to the typical developing group. Both selective attention of the dyslexic group and sustained attention of the ADHD group showed positive significant differences in the interesting-figure assessment, but sustained attention of the dyslexic group and selective attention of the ADHD group showed little difference in the interesting-figure assessment. Surprisingly, the typical developing group did not show any significant difference in the interesting-figure assessment, possibly because they had previously demonstrated a ceiling effect in the geometric

  11. New development in carbon quantum dots technical applications.

    Science.gov (United States)

    Shen, Li-Ming; Liu, Jing

    2016-08-15

    As a newly emerged member in carbon nanomaterials family, carbon quantum dots (CQDs) attracted everincreasing attention owing to their ultracompact size, excellent photoluminescence, favorable biocompatibility, versatile surface and superior electron transfer ability. The past decade has witnessed continuous advancements in the production of CQDs with high photoluminescence quantum yields for various applications. Herein, we track the newest development of CQDs with advanced physicochemical properties and their applications in sensing, bioimaging, nanomedicine and catalysis, and propose the challenges and perspectives in this exciting and promising field. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Attention competition with advertisement.

    Science.gov (United States)

    Cetin, Uzay; Bingol, Haluk O

    2014-09-01

    In the new digital age, information is available in large quantities. Since information consumes primarily the attention of its recipients, the scarcity of attention is becoming the main limiting factor. In this study, we investigate the impact of advertisement pressure on a cultural market where consumers have a limited attention capacity. A model of competition for attention is developed and investigated analytically and by simulation. Advertisement is found to be much more effective when the attention capacity of agents is extremely scarce. We have observed that the market share of the advertised item improves if dummy items are introduced to the market while the strength of the advertisement is kept constant.

  13. Attention competition with advertisement

    Science.gov (United States)

    Cetin, Uzay; Bingol, Haluk O.

    2014-09-01

    In the new digital age, information is available in large quantities. Since information consumes primarily the attention of its recipients, the scarcity of attention is becoming the main limiting factor. In this study, we investigate the impact of advertisement pressure on a cultural market where consumers have a limited attention capacity. A model of competition for attention is developed and investigated analytically and by simulation. Advertisement is found to be much more effective when the attention capacity of agents is extremely scarce. We have observed that the market share of the advertised item improves if dummy items are introduced to the market while the strength of the advertisement is kept constant.

  14. Probing silicon quantum dots by single-dot techniques

    Science.gov (United States)

    Sychugov, Ilya; Valenta, Jan; Linnros, Jan

    2017-02-01

    Silicon nanocrystals represent an important class of non-toxic, heavy-metal free quantum dots, where the high natural abundance of silicon is an additional advantage. Successful development in mass-fabrication, starting from porous silicon to recent advances in chemical and plasma synthesis, opens up new possibilities for applications in optoelectronics, bio-imaging, photovoltaics, and sensitizing areas. In this review basic physical properties of silicon nanocrystals revealed by photoluminescence spectroscopy, lifetime, intensity trace and electrical measurements on individual nanoparticles are summarized. The fabrication methods developed for accessing single Si nanocrystals are also reviewed. It is concluded that silicon nanocrystals share many of the properties of direct bandgap nanocrystals exhibiting sharp emission lines at low temperatures, on/off blinking, spectral diffusion etc. An analysis of reported results is provided in comparison with theory and with direct bandgap material quantum dots. In addition, the role of passivation and inherent interface/matrix defects is discussed.

  15. 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...

  16. Sustainable Transportation

    DEFF Research Database (Denmark)

    Hall, Ralph P.; Gudmundsson, Henrik; Marsden, Greg

    2014-01-01

    that relate to the construction and maintenance of transportation infrastructure and the operation or use of the different transportation modes. The concept of sustainable transportation emerged in response to these concerns as part of the broader notion of sustainable development. Given the transportation...

  17. Sustaining dairy

    NARCIS (Netherlands)

    Villarreal Herrera, Georgina

    2017-01-01

    Dairy in Europe has undergone many changes in the last few years—the abolition of milk production quotas being a fundamental one. This study explores these changes in relation to the sustained social and environmental viability of the sector and how dairy processors' sustainability

  18. Sustainable Universities

    DEFF Research Database (Denmark)

    Grindsted, Thomas Skou

    2011-01-01

    . Declarations tend to have impact on three trends. Firstly, there is emerging international consensus on the university’s role and function in relation to sustainable development; secondly, the emergence of national legislation, and thirdly, an emerging international competition to be leader in sustainable...... campus performance....

  19. Sustainable Transition

    DEFF Research Database (Denmark)

    Hansen, Ole Erik; Søndergård, Bent

    2014-01-01

    of agendas/vision, technologies, actors and institutions in the emergent design of an urban mobility system based on an electric car sharing system. Why. Designing for sustainability is a fundamental challenge for future design practices; designers have to obtain an ability to contribute to sustainable...

  20. Sustainable Learning

    Science.gov (United States)

    Cadwell, Louise; Dillon, Robert

    2011-01-01

    Green schools have moved into a new era that focuses on building a culture of sustainability in every aspect of learning in schools. In the early stages of sustainability education, the focus was on recycling and turning off the lights. Now, students and adults together are moving into the areas of advocacy and action that are based on a deep…

  1. Synthesis, properties and biomedical applications of carbon-based quantum dots: An updated review.

    Science.gov (United States)

    Namdari, Pooria; Negahdari, Babak; Eatemadi, Ali

    2017-03-01

    Carbon-based quantum dots (CQDs) are a newly developed class of carbon nano-materials that have attracted much interest and attention as promising competitors to already available semiconductor quantum dots owing to their un-comparable and unique properties. In addition, controllability of CQDs unique physiochemical properties is as a result of their surface passivation and functionalization. This is an update article (between 2013 and 2016) on the recent progress, characteristics and synthesis methods of CQDs and different advantages in varieties of applications. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  2. Cu2ZnSnS4 nanocrystals and graphene quantum dots for photovoltaics

    Science.gov (United States)

    Wang, Jun; Xin, Xukai; Lin, Zhiqun

    2011-08-01

    Semiconductor quantum dots exhibit great potential for applications in next generation high efficiency, low cost solar cells because of their unique optoelectronic properties. Cu2ZnSnS4 (CZTS) nanocrystals and graphene quantum dots (GQDs) have recently received much attention as building blocks for use in solar energy conversion due to their outstanding properties and advantageous characteristics, including high optical absorptivity, tunable bandgap, and earth abundant chemical composition. In this Feature Article, recent advances in the synthesis and utilization of CZTS nanocrystals and colloidal GQDs for photovoltaics are highlighted, followed by an outlook on the future research efforts in these areas.

  3. Global perception in simultanagnosia is not as simple as a game of connect-the-dots.

    Science.gov (United States)

    Dalrymple, Kirsten A; Bischof, Walter F; Cameron, David; Barton, Jason J S; Kingstone, Alan

    2009-07-01

    Simultanagnosia is a neuropsychological disorder characterized by a restriction of visuospatial attention. In addition, patients are able to identify local elements of a scene, but not the global whole. This may be due to a failure to scan and assemble local elements into a global whole (i.e. connect-the-dots). We monitored the eye movements of a simultanagnosic patient while she identified local and global elements of hierarchical letters. Scanning each local element was not necessary, nor sufficient, for successful global level identification. Our results argue against a connect-the-dots strategy of global identification and suggest that residual global processing may be occurring.

  4. Effects of external fields, dimension and polarization on the resonance fluorescence of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Vaseghi, B., E-mail: vaseghi@mail.yu.ac.ir; Razavi, S.M.

    2017-02-01

    In this paper simultaneous effects of external electric and magnetic fields, dimension and polarization on the resonance fluorescence spectrum and photon statistics of a spherical quantum dot with parabolic confinement are investigated. With special attention to the optical scattering processes resonance fluorescence spectrum and second-order correlation function are calculated and plotted for different external parameters. Our results show the occurrence of resonance fluorescence similar to atomic systems and considerable effects of external fields, quantum confinement and light polarization on the resonance fluorescence spectrum and second-order correlation function in the quantum dot systems. The existence of Mollow triplets and photon antibunching are strongly depend on these external agents.

  5. Biased attentional engagement with, and disengagement from, negative information: independent cognitive pathways to anxiety vulnerability?

    Science.gov (United States)

    Rudaizky, Daniel; Basanovic, Julian; MacLeod, Colin

    2014-01-01

    Cognitive models of anxiety propose that selective attention to negative information plays a causal role in heightened anxiety vulnerability and dysfunction. However, there has been theoretical disagreement concerning whether anxiety-linked attentional biases reflect enhanced attentional engagement with, or impaired attentional disengagement from, negative information. We contend that previous methodologies have not been optimal in terms of their capacity to differentiate both types of bias. The present study introduces a refined methodology, in which the conventional dot-probe task is modified in a novel manner to enable the independent assessment of these components of attention. The findings demonstrate that facilitated attentional engagement and impaired attentional disengagement are both characteristic of elevated levels of anxiety vulnerability. Moreover, these prove to be unrelated facets of attentional selectivity that independently contribute to variation in anxiety vulnerability. We discuss the possibility that these two types of attentional bias may represent independent pathways to anxiety vulnerability.

  6. Impairments of Attention and Effort Among Patients With Major Affective Disorders

    National Research Council Canada - National Science Library

    Cohen, Ronald; Lohr, Ilan; Paul, Robert; Boland, Robert

    2001-01-01

    .... There were low-effort and high-effort versions of each task. Significant group differences were consistently observed on tasks demanding sustained and focused attention, but not on tasks requiring visual selective attention...

  7. Dot-in-Well Quantum-Dot Infrared Photodetectors

    Science.gov (United States)

    Gunapala, Sarath; Bandara, Sumith; Ting, David; Hill, cory; Liu, John; Mumolo, Jason; Chang, Yia Chung

    2008-01-01

    Dot-in-well (DWELL) quantum-dot infrared photodetectors (QDIPs) [DWELL-QDIPs] are subjects of research as potentially superior alternatives to prior QDIPs. Heretofore, there has not existed a reliable method for fabricating quantum dots (QDs) having precise, repeatable dimensions. This lack has constituted an obstacle to the development of uniform, high-performance, wavelength-tailorable QDIPs and of focal-plane arrays (FPAs) of such QDIPs. However, techniques for fabricating quantum-well infrared photodetectors (QWIPs) having multiple-quantum- well (MQW) structures are now well established. In the present research on DWELL-QDIPs, the arts of fabrication of QDs and QWIPs are combined with a view toward overcoming the deficiencies of prior QDIPs. The longer-term goal is to develop focal-plane arrays of radiationhard, highly uniform arrays of QDIPs that would exhibit high performance at wavelengths from 8 to 15 m when operated at temperatures between 150 and 200 K. Increasing quantum efficiency is the key to the development of competitive QDIP-based FPAs. Quantum efficiency can be increased by increasing the density of QDs and by enhancing infrared absorption in QD-containing material. QDIPs demonstrated thus far have consisted, variously, of InAs islands on GaAs or InAs islands in InGaAs/GaAs wells. These QDIPs have exhibited low quantum efficiencies because the numbers of QD layers (and, hence, the areal densities of QDs) have been small typically five layers in each QDIP. The number of QD layers in such a device must be thus limited to prevent the aggregation of strain in the InAs/InGaAs/GaAs non-lattice- matched material system. The approach being followed in the DWELL-QDIP research is to embed In- GaAs QDs in GaAs/AlGaAs multi-quantum- well (MQW) structures (see figure). This material system can accommodate a large number of QD layers without excessive lattice-mismatch strain and the associated degradation of photodetection properties. Hence, this material

  8. AD/HD and the Capture of Attention by Briefly Exposed Delay-Related Cues: Evidence from a Conditioning Paradigm

    Science.gov (United States)

    Sonuga-Barke, Edmund J. S.; De Houwer, Jan; De Ruiter, Karen; Ajzenstzen, Michal; Holland, Sarah

    2004-01-01

    Background: The selective attention of children with attention deficit/hyperactivity disorder (AD/HD) to briefly exposed delay-related cues was examined in two experiments using a dot-probe conditioning paradigm. Method: Colour cues were paired with negatively (i.e., imposition of delay) and positively valenced cues (i.e., escape from or avoidance…

  9. Quantum Dot Light Emitting Diode

    Energy Technology Data Exchange (ETDEWEB)

    Keith Kahen

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  10. Quantum Dot Light Emitting Diode

    Energy Technology Data Exchange (ETDEWEB)

    Kahen, Keith

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  11. Analysis of Success Factors to Implement Sustainable Supply Chain Management Using Interpretive Structural Modeling Technique: A Real Case Perspective

    National Research Council Canada - National Science Library

    2017-01-01

    Sustainability draws increased supply chain management (SCM) attention. This article analyzes critical success to the assessment, evaluation, and attainment of sustainable supply chain management (SSCM...

  12. Attention Mosaics: Studies of Organizational Attention

    NARCIS (Netherlands)

    L. Carvalho de Mesquita Ferreira (Luciana)

    2010-01-01

    textabstractOrganizational studies emphasizing the role of attention in organizational behavior depart from the idea that organizations, like individuals, have limited capacity to attend to environmental stimuli. The bounded capacity of the organizations to respond to stimuli is conditioned by the

  13. Sustainability transition dynamics: Towards overcoming policy resistance

    NARCIS (Netherlands)

    Gooyert, V. de; Rouwette, E.A.J.A.; Kranenburg, H.L. van; Freeman, R.E.; Breen, H.J. van

    2016-01-01

    Sustainability transitions receive major scholarly attention, often explicitly with the intention to develop policy recommendations aimed towards progressing such transitions. Despite these efforts, many implemented transition policies have not been able to meet expectations. This tendency of

  14. Managing sustainability in management education

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    Environmental issues are increasingly becoming a key business concern at local, national, international and global levels. Consequently, environmental issues and sustainability have found their way into management education in terms of business ethics, corporate social or sustainability responsib......Environmental issues are increasingly becoming a key business concern at local, national, international and global levels. Consequently, environmental issues and sustainability have found their way into management education in terms of business ethics, corporate social or sustainability...... practical and theoretical problems. Among others, problems concerning trade-offs and complexity. This paper proposes an approach to sustainability in management education which help to initiate such critical reflection and discussion concerning trade-offs and complexity by drawing attention to the complex...... network of relations in which a given business or industry is embedded....

  15. Effects of Psychiatric Symptoms on Attention in North Korean Refugees

    Science.gov (United States)

    Lee, Yu Jin; Jun, Jin Yong; Park, Juhyun; Kim, Soohyun; Gwak, Ah Reum; Lee, So Hee; Yoo, So Young

    2016-01-01

    Objective We investigated the performance of North Korean refugees on attention tasks, and the relationship between that performance and psychiatric symptoms. Methods Sustained and divided attention was assessed using the computerized Comprehensive Attention Test in North Korean refugees and in South Koreans. All participants also completed the Beck Depression Inventory, the Beck Anxiety Inventory, the Impact of Event Scale-Revised and the Dissociative Experiences Scale-II (DES-II). Results The North Korean refugees showed slower reaction times (RTs) on the visual sustained attention task compared to the South Koreans after controlling for age and sex. North Korean refugees had a greater number of omission errors (OEs) on the divided attention task and a higher standard deviation (SD) of RT. Total DES-II scores of the North Korean refugees were associated with the number of OEs and the SD of RT on the sustained attention task, and with the number of OEs on the divided attention task. Conclusion North Korean refugees showed poorer performance on computerized attention tasks. In addition, attention deficit among North Korean refugees was associated with their dissociative experiences. Our results suggest that refugees may have attention deficits, which may be related to their psychiatric symptoms, particularly dissociation. PMID:27757125

  16. Sustainable Tourism in Practice: Promoting or Perverting the Quest for a Sustainable Development?

    OpenAIRE

    Carlo Aall

    2014-01-01

    Sustainable tourism has achieved the status of being the superior goal in Norwegian government tourism policy, and is attaining much attention in the international scientific and political discourse on tourism. However, have policies on sustainable tourism and related concepts actually managed to make tourism more sustainable? This article seeks to address this question by first presenting the history of sustainable tourism and related concepts, and specifically analyzing how the triple botto...

  17. Quantum dots: lasers and amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Bimberg, Dieter; Ledentsov, Nikolai [Institut fuer Festkoerperphysik, PN5-2, Technische Universitaet Berlin, Hardenbergstrasse 36, 10623 (Germany)

    2003-06-25

    Continuous wave room-temperature output power of {approx} 3 W for edge emitters and of 1.2 mW for vertical-cavity surface-emitting lasers is realized for GaAs-based devices using InAs quantum dots (QDs) operating at 1.3 {mu}m. Characteristic temperatures up to 170 K below 330 K are realized. Simultaneously, differential efficiency exceeds 80% for these devices. Lasers emitting up to 12 W at 1140-1160 nm are useful as pump sources for Tm{sup 3+}-doped fibres for frequency up-conversion to 470 nm. Both types of lasers show transparency current densities of 6 A cm{sup -2} per dot layer, {eta}{sub int} = 98% and {alpha}{sub i} around 1.5 cm{sup -1}. Long operation lifetimes (above 3000 h at 50 deg C heatsink temperature at 1.5 W CW) and improved radiation hardness as compared to quantum well (QW) devices are manifested. Cut-off frequencies of about 10 GHz at 1100 nm and 6 GHz at 1300 nm and low {alpha} factors resulting in reduced filamentation and improved M{sup 2} values in single-mode operation are realized. Quantum dot semiconductor optical amplifiers (QD SOAs) demonstrate gain recovery times of 120-140 fs, 4-7 times faster than bulk/QW SOAs. The breakthrough became possible due to the development of self-organized growth in QD technology. (topical review)

  18. Moving to Capture Children's Attention: Developing a Methodology for Measuring Visuomotor Attention.

    Directory of Open Access Journals (Sweden)

    Liam J B Hill

    Full Text Available Attention underpins many activities integral to a child's development. However, methodological limitations currently make large-scale assessment of children's attentional skill impractical, costly and lacking in ecological validity. Consequently we developed a measure of 'Visual Motor Attention' (VMA-a construct defined as the ability to sustain and adapt visuomotor behaviour in response to task-relevant visual information. In a series of experiments, we evaluated the capability of our method to measure attentional processes and their contributions in guiding visuomotor behaviour. Experiment 1 established the method's core features (ability to track stimuli moving on a tablet-computer screen with a hand-held stylus and demonstrated its sensitivity to principled manipulations in adults' attentional load. Experiment 2 standardised a format suitable for use with children and showed construct validity by capturing developmental changes in executive attention processes. Experiment 3 tested the hypothesis that children with and without coordination difficulties would show qualitatively different response patterns, finding an interaction between the cognitive and motor factors underpinning responses. Experiment 4 identified associations between VMA performance and existing standardised attention assessments and thereby confirmed convergent validity. These results establish a novel approach to measuring childhood attention that can produce meaningful functional assessments that capture how attention operates in an ecologically valid context (i.e. attention's specific contribution to visuomanual action.

  19. Barrier Engineered Quantum Dot Infrared Photodetectors

    Science.gov (United States)

    2015-06-01

    AFRL-RV-PS- AFRL-RV-PS- TR-2015-0111 TR-2015-0111 BARRIER ENGINEERED QUANTUM DOT INFRARED PHOTODETECTORS Sanjay Krishna Center for High Technology...2011 – 22 May 2012 4. TITLE AND SUBTITLE Barrier Engineered Quantum Dot Infrared Photodetectors 5a. CONTRACT NUMBER FA9453-12-1-0336 5b. GRANT...is Unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT To investigate barrier engineered designs to reduce the dark current in quantum dot infrared

  20. Attention to Advertising

    OpenAIRE

    Nilsson, Carl Patrik

    2006-01-01

    Attention to Advertising Carl Patrik Nilsson, Umeå School of Business, Umeå University SE-901 87 Umeå, Sweden Abstract In advertising, capturing consumers’ attention is imperative. Yet, how attention to advertising works in a World Wide Web context has not been researched extensively. This area is the main focus of this research. The World Wide Web is an interactive medium which has characteristics that deviate from traditional media channels. Considering the unique properties of the World Wi...

  1. Objective assessment of attention in delirium: a narrative review.

    Science.gov (United States)

    Tieges, Zoë; Brown, Laura J E; MacLullich, Alasdair M J

    2014-12-01

    Inattention is a core feature of delirium, and valid assessment of attention is central to diagnosis. Methods of measuring attention in delirium can be divided into two broad categories: (i) objective neuropsychological testing; and (ii) subjective grading of behaviour during interview and clinical examination. Here, we review and critically evaluate studies of objective neuropsychological testing of attention in delirium. We examine the implications of these studies for delirium detection and monitoring in clinical practice and research, and how these studies inform understanding of the nature of attentional deficits in delirium. Searches of MEDLINE and ISI Web of Knowledge databases were performed to identify studies in which objective tests of attention had been administered to patients with delirium, who had been diagnosed using DSM or ICD criteria. Sixteen publications were identified. The attention tests administered in these studies were grouped into the following categories: measures of attention span, vigilance tests, other pen-and-paper tests (e.g. Trail Making Test) and computerised tests of speeded reaction, vigilance and sustained attention. Patients with delirium showed deficits on all tasks, although most tasks were not considered pure measures of attention. Five papers provided data on differential diagnosis from dementia. Cancellation tests, spatial span tests and computerised tests of sustained attention discriminated delirium from dementia. Five studies presented reliability or validity statistics. The existing evidence base on objective assessment of attention in delirium is small. Objective testing of attention is underdeveloped but shows considerable promise in clinical practice and research. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Today's DOT and the quest for more accountable organizational structures.

    Science.gov (United States)

    2005-12-01

    This study investigates the impact of DOT organizational structures on effective transportation planning and performance. A review of the 50 state DOT authorizing statutes and DOT organizational charts found minimal differences in organizational stru...

  3. Announcements to Attentive Agents

    DEFF Research Database (Denmark)

    Bolander, Thomas; van Ditmarsch, Hans; Herzig, Andreas

    2016-01-01

    In public announcement logic it is assumed that all agents pay attention to the announcement. Weaker observational conditions can be modelled in action model logic. In this work, we propose a version of public announcement logic wherein it is encoded in the states of the epistemic model which...... agents pay attention to the announcement. This logic is called attention-based announcement logic. We give an axiomatization of the logic and prove that complexity of satisfiability is the same as that of public announcement logic, and therefore lower than that of action model logic. An attention...

  4. The effects of age on attentional disengagement and inhibitory control

    Directory of Open Access Journals (Sweden)

    2015-09-01

    Full Text Available Aims: Previous research on the Oculomotor Capture Task (OCT found that older adults make a greater percentage of reflexive saccades to a distractor than younger adults. This finding may be due to a decrease in ability to disengage attention. This study is aimed at determining whether performance on a Posner attentional disengagement task, and a Flanker interference task can predict error rates on the OCT in older adults. It is hypothesised that participants' performance on the Posner and Flanker tasks will positively correlate with their performance on the OCT.   Method: Participants (n = 27 completed three tasks. The OCT involved participants looking at six grey dots on a computer. After 1000ms the colour of the five dots changed to red. Simultaneously, an extra dot (distractor appeared. Participants had to look at the remaining grey dot. The Flanker task required participants to respond to the identity of a letter, H or E, flanked by either congruent or incongruent letters. The Posner task comprised a red cue, followed by a square that had a gap on the top or bottom of it. Participants had to indicate which it was. Results: Results showed that there was a moderate correlation between percentage captures and the difference in RT on the Posner task, r = .35, p = .067. There was a significant correlation between age and percentage capture on the OCT, r = .53, p = .004.                         Conclusions: The results showed that percentage captures increased with age, supporting previous research.  The moderate correlation between percentage captures and performance on the Posner task suggests that time taken to disengage attention from a distractor may predict performance on the OCT.

  5. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  6. Quantum dots for quantum information technologies

    CERN Document Server

    2017-01-01

    This book highlights the most recent developments in quantum dot spin physics and the generation of deterministic superior non-classical light states with quantum dots. In particular, it addresses single quantum dot spin manipulation, spin-photon entanglement and the generation of single-photon and entangled photon pair states with nearly ideal properties. The role of semiconductor microcavities, nanophotonic interfaces as well as quantum photonic integrated circuits is emphasized. The latest theoretical and experimental studies of phonon-dressed light matter interaction, single-dot lasing and resonance fluorescence in QD cavity systems are also provided. The book is written by the leading experts in the field.

  7. Preparation of tin oxide quantum dots

    Science.gov (United States)

    Fauzi, N. F. S. M.; Kamarulzaman, N.; Kasim, M. F.; Chayed, N. F.; Aziz, N. D. A.

    2017-09-01

    Quantum dots are interesting nanostructures with have novel physical and chemical characteristics. It is not an easy task to obtain quantum dots because materials tend to agglomerate. In this work, SnO2 quantum dots have been successfully synthesized via a simple and low cost method which is the sol-gel method. Thermal analysis of the precursors were carried out using a Simultaneous Thermogravimetric Analyzer (STA). The annealed samples were characterized using X-Ray Diffraction (XRD) for phase studies. Finally, the crystallite size and morphology of tin oxide quantum dots were determined using Field Emission Scanning Electron Microscopy (FESEM).

  8. POLARON IN CYLINDRICAL AND SPHERICAL QUANTUM DOTS

    Directory of Open Access Journals (Sweden)

    L.C.Fai

    2004-01-01

    Full Text Available Polaron states in cylindrical and spherical quantum dots with parabolic confinement potentials are investigated applying the Feynman variational principle. It is observed that for both kinds of quantum dots the polaron energy and mass increase with the increase of Frohlich electron-phonon coupling constant and confinement frequency. In the case of a spherical quantum dot, the polaron energy for the strong coupling is found to be greater than that of a cylindrical quantum dot. The energy and mass are found to be monotonically increasing functions of the coupling constant and the confinement frequency.

  9. Transmission and scarring in graphene quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Huang Liang; Lai Yingcheng; Ferry, David K; Akis, Richard; Goodnick, Stephen M [Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287 (United States)

    2009-08-26

    We study electronic transport in quantum-dot structures made of graphene. Focusing on the rectangular dot geometry and utilizing the non-equilibrium Green's function to calculate the transmission in the tight-binding framework, we find significant fluctuations in the transmission as a function of the electron energy. The fluctuations are correlated with the formation of quantum scarring states, or pointer states in the dot. Both enhancement and suppression of transmission have been observed. As the size of the quantum dot is increased, more scarring states can be formed, leading to stronger transmission or conductance fluctuations.

  10. Mixed-quantum-dot solar cells.

    Science.gov (United States)

    Yang, Zhenyu; Fan, James Z; Proppe, Andrew H; Arquer, F Pelayo García de; Rossouw, David; Voznyy, Oleksandr; Lan, Xinzheng; Liu, Min; Walters, Grant; Quintero-Bermudez, Rafael; Sun, Bin; Hoogland, Sjoerd; Botton, Gianluigi A; Kelley, Shana O; Sargent, Edward H

    2017-11-06

    Colloidal quantum dots are emerging solution-processed materials for large-scale and low-cost photovoltaics. The recent advent of quantum dot inks has overcome the prior need for solid-state exchanges that previously added cost, complexity, and morphological disruption to the quantum dot solid. Unfortunately, these inks remain limited by the photocarrier diffusion length. Here we devise a strategy based on n- and p-type ligands that judiciously shifts the quantum dot band alignment. It leads to ink-based materials that retain the independent surface functionalization of quantum dots, and it creates distinguishable donor and acceptor domains for bulk heterojunctions. Interdot carrier transfer and exciton dissociation studies confirm efficient charge separation at the nanoscale interfaces between the two classes of quantum dots. We fabricate the first mixed-quantum-dot solar cells and achieve a power conversion of 10.4%, which surpasses the performance of previously reported bulk heterojunction quantum dot devices fully two-fold, indicating the potential of the mixed-quantum-dot approach.

  11. Sustainable consumption

    DEFF Research Database (Denmark)

    Prothero, Andrea; Dobscha, Susan; Freund, Jim

    2011-01-01

    This essay explores sustainable consumption and considers possible roles for marketing and consumer researchers and public policy makers in addressing the many sustainability challenges that pervade our planet. Future research approaches to this interdisciplinary topic need to be comprehensive...... and systematic and will benefit from a variety of different perspectives. There are a number of opportunities for future research, and three areas are explored in detail. First, the essay considers the inconsistency between the attitudes and behaviors of consumers with respect to sustainability; next, the agenda...... is broadened to explore the role of individual citizens in society; and finally, a macro institutional approach to fostering sustainability is explored. Each of these areas is examined in detail and possible research avenues and public policy initiatives are considered within each of these separate...

  12. Stabilizing Sustainability

    DEFF Research Database (Denmark)

    Reitan Andersen, Kirsti

    The publication of the Brundtland Report in 1987 put the topic of sustainable development on the political and corporate agenda. Defining sustainable development as “a development that meets the needs of the future without compromising the ability of future generations to meet their own needs......” (WCED, 1987, p. 43), the Report also put a positive spin on the issue of sustainability by upholding capitalist beliefs in the possibility of infinite growth in a world of finite resources. While growth has delivered benefits, however, it has done so unequally and unsustainably. This thesis focuses...... on the textile and fashion industry, one of the world’s most polluting industries and an industry to some degree notorious for leading the ‘race to the bottom’ in global labour standards. Despite being faced with increasing demands to practise sustainability, most textile and fashion companies continue to fail...

  13. Sustainability reporting

    NARCIS (Netherlands)

    Kolk, A.

    2005-01-01

    This article gives an overview of developments in sustainability (also sometimes labelled corporate social responsibility) reporting. The article will first briefly indicate how accountability on social and environmental issues started, already in the 1970s when social reports were published.

  14. Sustainable Cities

    DEFF Research Database (Denmark)

    Georg, Susse; Garza de Linde, Gabriela Lucía

    Judging from the number of communities and cities striving or claiming to be sustainable and how often eco-development is invoked as the means for urban regeneration, it appears that sustainable and eco-development have become “the leading paradigm within urban development” (Whitehead 2003......), urban design competitions are understudied mechanisms for bringing about field level changes. Drawing on actor network theory, this paper examines how urban design competitions may bring about changes within the professional field through the use of intermediaries such as a sustainable planning....../assessment tool. The context for our study is urban regeneration in one Danish city, which had been suffering from industrial decline and which is currently investing in establishing a “sustainable city”. Based on this case study we explore how the insights and inspiration evoked in working with the tool...

  15. Sustainable responsibilities?

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    2015-01-01

    This working paper analyzes the conceptions of corporate responsibility for sustainable development in EU policies on CSR. The notion of corporate responsibility has until recently been limited to economical and legal responsibilities. Based on this narrow conception of corporate responsibility.......e. a combination of destruction and construction, this chapter will deconstruct conceptions of responsibility for sustainable development in these EU documents on CSR. A deconstructive conceptual analysis involves destructing dominant interpretations of a text and allowing for constructions of alternative...... such as sustainability actually means, but on what the concept says and does not say. A deconstructive analysis of EU policies on CSR, then, pinpoints that such policies are sites of conceptual struggles. This kind of analysis is suitable for studying conceptions of corporate responsibility for sustainable development...

  16. Agriculture: Sustainability

    Science.gov (United States)

    Sustainability creates and maintains the conditions under which humans and nature can exist in productive harmony, that permit fulfilling the food, feed, and fiber needs of our country and the social, economic and other requirements.

  17. The Synthesis of Amphiphilic Luminescent Graphene Quantum Dot and Its Application in Miniemulsion Polymerization

    Directory of Open Access Journals (Sweden)

    Minxiang Zeng

    2016-01-01

    Full Text Available Although emulsion applications of microscale graphene sheets have attracted much attention recently, nanoscale graphene platelets, namely, graphene quantum dots (GQDs, have been rarely explored in interface science. In this work, we study the interfacial behaviors and emulsion phase diagrams of hydrophobic-functionalized graphene quantum dots (C18-GQDs. Distinctive from pristine graphene quantum dots (p-GQDs, C18-GQDs show several interesting surface-active properties including high emulsification efficiency in stabilizing dodecane-in-water emulsions. We then utilize the C18-GQDs as surfactants in miniemulsion polymerization of styrene, achieving uniform and relatively small polystyrene nanospheres. The high emulsification efficiency, low production cost, uniform morphology, intriguing photoluminescence, and extraordinary stability render C18-GQDs an attractive alternative in surfactant applications.

  18. Decolonising sustainability: Subverting and appropriating ...

    African Journals Online (AJOL)

    This essay explores some possibilities for decolonising the concept of sustainability in southern African discourses of environmental education by drawing attention to examples of the ways in which imperialist interests appear to be privileged in local expressions of selected transnational mythologies of social change.

  19. Language Education for Sustainable Development

    Science.gov (United States)

    Zygmunt, Tomasz

    2016-01-01

    Nowadays, education for sustainable development starts covering wider and wider spheres of interest and human activity. Out of the three main spheres of interest, such as environmental, economic, and socio-cultural, the first two mentioned here seem to be given more attention than the sphere of socio-cultural activity. In this respect, the aim of…

  20. Sustainable finance

    OpenAIRE

    Boersma-de Jong, Margreet F.

    2012-01-01

    Presentation for Springschool of Strategy, University of Groningen, 10 October 2012. The role of CSR is to stimulate ethical behaviour, and as a result, mutual trust in society. Advantage of CSR for the company and the evolution of CSR. From CSR to Sustainable Finance: how does CSR influence Sustainable Business Administration & Management Accounting, Financial Leadership and what is the importance of CSR in the financial sector

  1. SUSTAINABLE TRANSPORTATION

    Directory of Open Access Journals (Sweden)

    Linda STEG

    2007-01-01

    Full Text Available This paper discusses possible contributions of psychologists to sustainable transportation. It is argued that in order to reach sustainable transportation, among others, behaviour changes of individual car users are needed. As transport policies will be more effective if they target important antecedents of travel behaviour, first, factors influencing such behaviour are discussed. It is argued that car use is very attractive and sometimes even necessary for many different reasons. This implies that a combination of policies is called for, each targeting different factors that support car use and hinder the use of more sustainable modes of transport. Next, the paper elaborates on policy strategies that may be employed to achieve sustainable transportation by changing car use. Increasing the attractiveness of sustainable transport modes by means of pull measures seems not sufficient to reduce the level of car use. Besides, car use should be made less attractive by means of push measures to force drivers to reconsider their travel behaviour. The acceptability of such policies may be increased by clearly communicating the aim of these policies, and the expected positive consequences (e.g., less congestion, improved environmental quality. Moreover, possible negative effects for individual freedom may be compensated by implementing additional policies aimed at facilitating the use of sustainable transport modes.

  2. Sustainable markets for sustainable energy

    Energy Technology Data Exchange (ETDEWEB)

    Millan, J.; Smyser, C.

    1997-12-01

    The author discusses how the Inter-American Development Bank (IDB) is involved in sustainable energy development. It presently has 50 loans and grants for non conventional renewable energy projects and ten grants for efficiency programs for $600 and $17 million respectively, representing 100 MW of power. The IDB is concerned with how to create a sustainable market for sustainable energy projects. The IDB is trying to work with government, private sector, NGOs, trading allies, credit sources, and regulators to find proper roles for such projects. He discusses how the IDB is working to expand its vision and objectives in renewable energy projects in Central and South America.

  3. Quantum Dot Spectrum Converters for Enhanced High Efficiency Photovoltaics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This research proposes to enhance solar cell efficiency, radiation resistance and affordability. The Quantum Dot Spectrum Converter (QDSC) disperses quantum dots...

  4. Laughter catches attention!

    NARCIS (Netherlands)

    Pinheiro, Ana P; Barros, Carla; Dias, Marcelo; Kotz, Sonja A

    2017-01-01

    In social interactions, emotionally salient and sudden changes in vocal expressions attract attention. However, only a few studies examined how emotion and attention interact in voice processing. We investigated neutral, happy (laughs) and angry (growls) vocalizations in a modified oddball task.

  5. Unmasking the attentional blink

    NARCIS (Netherlands)

    Nieuwenstein, Mark R.; Potter, Mary C.; Theeuwes, Jan

    2009-01-01

    When asked to identify 2 visual targets (T I and T2 for the 1st and 2nd targets. respectively) embedded in a sequence of distractors, observers will often fail to identify T2 when it appears within 200-500 Ins of T1-an effect called the attentional blink. Recent work shows that attention does not

  6. Neural Mechanisms of Attention

    Science.gov (United States)

    1993-05-21

    attention deficit hyperactivity disorder ( ADHD ). These disorders may encompass a number of other cognitive deficits, but many theories focus on the...trial of methylphenidate in black adolescents. Attentional, behavioral, and physiological effects. CLINICAL.PEDIATRICS., 27,74-81. Bruto, V...Nakamura, K., Nishijo, H., & Fukuda, M. (1986). Hypothalamic neuron involvement in integration of reward , aversion, and cue signals. Journal of

  7. Fluorescence resonance energy transfer measured by spatial photon migration in CdSe-ZnS quantum dots colloidal systems as a function of concentration

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, G.; Monte, A. F. G.; Reis, A. F.; Messias, D. N. [Laboratório de Espectroscopia Óptica, Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, MG 38400-902 (Brazil)

    2014-11-17

    The study of the spatial photon migration as a function of the concentration brings into attention the problem of the energy transfer in quantum dot embedded systems. By measuring the photon propagation and its spatial dependence, it is possible to understand the whole dynamics in a quantum dot system, and also improve their concentration dependence to maximize energy propagation due to radiative and non-radiative processes. In this work, a confocal microscope was adapted to scan the spatial distribution of photoluminescence from CdSe-ZnS core-shell quantum dots in colloidal solutions. The energy migration between the quantum dots was monitored by the direct measurement of the photon diffusion length, according to the diffusion theory. We observed that the photon migration length decreases by increasing the quantum dot concentration, this kind of behavior has been regarded as a signature of Förster resonance energy transfer in the system.

  8. Attention and choice

    DEFF Research Database (Denmark)

    Orquin, Jacob Lund; Mueller Loose, Simone

    2013-01-01

    This paper reviews studies on eye movements in decision making, and compares their observations to theoretical predictions concerning the role of attention in decision making. Four decision theories are examined: rational models, bounded rationality, evidence accumulation, and parallel constraint...... satisfaction models. Although most theories were confirmed with regard to certain predictions, none of the theories adequately accounted for the role of attention during decision making. Several observations emerged concerning the drivers and down-stream effects of attention on choice, suggesting...... that attention processes plays an active role in constructing decisions. So far, decision theories have largely ignored the constructive role of attention by assuming that it is entirely determined by heuristics, or that it consists of stochastic information sampling. The empirical observations reveal...

  9. Mathematics for Life: Sustainable Mathematics Education

    Science.gov (United States)

    Renert, Moshe

    2011-01-01

    Ecological sustainability has not been a major focus of mathematics education research, even though it has attracted considerable attention in other areas of educational research in the past decade. The connections between mathematics education and ecological sustainability are not readily apparent. This paper explores how mathematics educators…

  10. Cyclic Variations in Sustained Human Performance

    Science.gov (United States)

    Aue, William R.; Arruda, James E.; Kass, Steven J.; Stanny, Claudia J.

    2009-01-01

    Biological rhythms play a prominent role in the modulation of human physiology and behavior. [Smith, K., Valentino, D., & Arruda, J. (2003). "Rhythmic oscillations in the performance of a sustained attention task." "Journal of Clinical and Experimental Neuropsychology," 25, 561-570] suggested that sustained human performance may systematically…

  11. Hospitableness and sustainable development: New responsibilities ...

    African Journals Online (AJOL)

    [CC BY 4.0] (http://creativecommons.org/licenses/by/4.0). Introduction. Within the hospitality industry, as in other industries, attention is given to environmental sustainability. Unfortunately, however, most hospitality companies are lagging behind in the process of becoming more sustainable (van Rheede & Blomme, 2012a).

  12. Education for Sustainable Development: Knowledge and ...

    African Journals Online (AJOL)

    The United Nations' launch of the Decade of Education for Sustainable Development in 2005 has focused international attention on the concept of education for sustainable development (ESD). This paper covers the emergence of ESD in relation to environmental education in South Africa. It critiques the core concept, ...

  13. Sustainable Design: The Next Industrial Revolution?

    Science.gov (United States)

    Baird, Stephen L.

    2008-01-01

    An insatiable appetite for energy, a burgeoning world population, and a heightened awareness of climate change are focusing global attention on sustainability, an issue that may very well determine the future course of civilization. The pursuit of a sustainable lifestyle today is of paramount importance for future generations. Achieving…

  14. Metrics for Green and Sustainable Software.

    NARCIS (Netherlands)

    Condori-Fernandez, O.N.; Procaccianti, G.; Ali, N.; Daneva, M.

    2014-01-01

    Several initiatives have been proposed in recent years with the purpose of investigating how to tackle sustainability issues within software systems and software engineering. However, there is a lack of attention from the research community in exploring sustainability as an emergent quality property

  15. Partitioning ecosystems for sustainability.

    Science.gov (United States)

    Murray, Martyn G

    2016-03-01

    Decline in the abundance of renewable natural resources (RNRs) coupled with increasing demands of an expanding human population will greatly intensify competition for Earth's natural resources during this century, yet curiously, analytical approaches to the management of productive ecosystems (ecological theory of wildlife harvesting, tragedy of the commons, green economics, and bioeconomics) give only peripheral attention to the driving influence of competition on resource exploitation. Here, I apply resource competition theory (RCT) to the exploitation of RNRs and derive four general policies in support of their sustainable and equitable use: (1) regulate resource extraction technology to avoid damage to the resource base; (2) increase efficiency of resource use and reduce waste at every step in the resource supply chain and distribution network; (3) partition ecosystems with the harvesting niche as the basic organizing principle for sustainable management of natural resources by multiple users; and (4) increase negative feedback between consumer and resource to bring about long-term sustainable use. A simple policy framework demonstrates how RCT integrates with other elements of sustainability science to better manage productive ecosystems. Several problem areas of RNR management are discussed in the light of RCT, including tragedy of the commons, overharvesting, resource collapse, bycatch, single species quotas, and simplification of ecosystems.

  16. Framing sustainability in a telecoupled world

    OpenAIRE

    Jianguo Liu; Vanessa Hull; Mateus Batistella; Ruth DeFries; Thomas Dietz; Feng Fu; Hertel, Thomas W.; R. Cesar Izaurralde; Eric F. Lambin; Shuxin Li; Luiz A. MARTINELLI; McConnell, William J.; MORAN,EMILIO F.; Rosamond Naylor; Zhiyun Ouyang

    2013-01-01

    Interactions between distant places are increasingly widespread and influential, often leading to unexpected outcomes with profound implications for sustainability. Numerous sustainability studies have been conducted within a particular place with little attention to the impacts of distant interactions on sustainability in multiple places. Although distant forces have been studied, they are usually treated as exogenous variables and feedbacks have rarely been considered. To understand and int...

  17. Implementing Sustainable Supply Chain in PLM

    OpenAIRE

    Rosich, Maria,; Le Duigou, Julien; BOSCH-MAUCHAND, Magali

    2012-01-01

    Part V: Product and Asset Lifecycle Management; International audience; Sustainable supply chain has received growing attention in recent years. Due to the lack of relevant data to permit a credible analysis of sustainable supply chain, it is quite hard to propose an analytic method to guide sustainable supply chain strategies. Product Lifecycle Management (PLM) has provided companies with useful software to manage information using product as a central element. It consolidates all the inform...

  18. Mindfulness Meditation Improves Mood, Quality of Life, and Attention in Adults with Attention Deficit Hyperactivity Disorder

    Directory of Open Access Journals (Sweden)

    Viviane Freire Bueno

    2015-01-01

    Full Text Available Objective. Adults with attention deficit hyperactivity disorder (ADHD display affective problems and impaired attention. Mood in ADHD can be improved by mindful awareness practices (MAP, but results are mixed regarding the enhancement of attentional performance. Here we evaluated MAP-induced changes in quality of life (QoL, mood, and attention in adult ADHD patients and controls using more measures of attention than prior studies. Methods. Twenty-one ADHD patients and 8 healthy controls underwent 8 weekly MAP sessions; 22 similar patients and 9 controls did not undergo the intervention. Mood and QoL were assessed using validated questionnaires, and attention was evaluated using the Attentional Network Test (ANT and the Conners Continuous Performance Test (CPT II, before and after intervention. Results. MAP enhanced sustained attention (ANT and detectability (CPT II and improved mood and QoL of patients and controls. Conclusion. MAP is a complementary intervention that improves affect and attention of adults with ADHD and controls.

  19. Modeling and simulation of InGaN/GaN quantum dots solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Aissat, A., E-mail: sakre23@yahoo.fr [LATSI Laboratory, Faculty of Technology, University of Blida 1 (Algeria); LASICOMLaboratory, Faculty of Sciences, University of Blida 1 (Algeria); Benyettou, F. [LASICOMLaboratory, Faculty of Sciences, University of Blida 1 (Algeria); Vilcot, J. P. [Institute of Electronics, Micro-Electronics and Nanotechnologies,UMR CNRS 8520, Université des Sciences et Technologies de Lille1, Avenue Poincaré, CS 60069, 59652 Villeneuve d’Ascq (France)

    2016-07-25

    Currently, quantum dots have attracted attention in the field of optoelectronics, and are used to overcome the limits of a conventional solar cell. Here, an In{sub 0.25}Ga{sub 0.75}N/GaN Quantum Dots Solar Cell has been modeled and simulated using Silvaco Atlas. Our results show that the short circuit current increases with the insertion of the InGaN quantum dots inside the intrinsic region of a GaN pin solar cell. In contrary, the open circuit voltage decreases. A relative optimization of the conversion efficiency of 54.77% was achieved comparing a 5-layers In{sub 0.25}Ga{sub 0.75}N/GaN quantum dots with pin solar cell. The conversion efficiency begins to decline beyond 5-layers quantum dots introduced. Indium composition of 10 % improves relatively the efficiency about 42.58% and a temperature of 285 K gives better conversion efficiency of 13.14%.

  20. Nitrogen-Doped Carbon Dots for "green" Quantum Dot Solar Cells.

    Science.gov (United States)

    Wang, Hao; Sun, Pengfei; Cong, Shan; Wu, Jiang; Gao, Lijun; Wang, Yun; Dai, Xiao; Yi, Qinghua; Zou, Guifu

    2016-12-01

    Considering the environment protection, "green" materials are increasingly explored for photovoltaics. Here, we developed a kind of quantum dots solar cell based on nitrogen-doped carbon dots. The nitrogen-doped carbon dots were prepared by direct pyrolysis of citric acid and ammonia. The nitrogen-doped carbon dots' excitonic absorption depends on the N-doping content in the carbon dots. The N-doping can be readily modified by the mass ratio of reactants. The constructed "green" nitrogen-doped carbon dots solar cell achieves the best power conversion efficiency of 0.79 % under AM 1.5 G one full sun illumination, which is the highest efficiency for carbon dot-based solar cells.

  1. Attentional bias in snus users: an experimental study.

    Directory of Open Access Journals (Sweden)

    Rune Aune Mentzoni

    Full Text Available The use of nicotine in the form of "snus" is substantial and increasing in some geographic areas, in particular among young people. It has previously been suggested that addictions may operate through a mechanism of attentional bias, in which stimuli representative of the dependent substance increase in salience, thus increasing the addictive behavior. However, this hypothesis has not been tested for the case of snus. The current experiment used a modified Stroop task and a dot-probe task to investigate whether 40 snus users show an attentional bias towards snus-relevant stimuli, compared to 40 non-snus users. There were no significant differences between the two groups on reaction times or accuracy on either Stroop or dot-probe task, thus failing to show an attentional bias towards snus-relevant stimuli for snus users. This could imply that other mechanisms may contribute to maintenance of snus use than for other addictions. However, this is the first experimental study investigating attentional bias in snus users, and more research is warranted.

  2. Threat Related Selective Attention Predicts Treatment Success in Childhood Anxiety Disorders

    Science.gov (United States)

    Legerstee, Jeroen S.; Tulen, Joke H. M.; Kallen, Victor L.; Dieleman, Gwen C.; Treffers, Philip D. A.; Verhulst, Frank C.; Utens, Elisabeth M. W. J.

    2009-01-01

    Threat-related selective attention was found to predict the success of the treatment of childhood anxiety disorders through administering a pictorial dot-probe task to 131 children with anxiety disorders prior to cognitive behavioral therapy. The diagnostic status of the subjects was evaluated with a semistructured clinical interview at both pre-…

  3. Adiabatic pumping through interacting quantum dots

    OpenAIRE

    Splettstoesser, Janine; Governale, Michele; König, Jürgen; Fazio, Rosario

    2005-01-01

    We present a general formalism to study adiabatic pumping through interacting quantum dots. We derive a formula that relates the pumped charge to the local, instantaneous Green function of the dot. This formula is then applied to the infinite-U Anderson model both for weak and strong tunnel-coupling strengths.

  4. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.

    2002-01-01

    We have produced GaAs-based quantum-dot edge-emitting lasers operating at 1.16 mu m with record-low transparency current, high output power, and high internal quantum efficiencies. We have also realized GaAs-based quantum-dot lasers emitting at 1.3 mu m, both high-power edge emitters and low...

  5. Thick-shell nanocrystal quantum dots

    Science.gov (United States)

    Hollingsworth, Jennifer A [Los Alamos, NM; Chen, Yongfen [Eugene, OR; Klimov, Victor I [Los Alamos, NM; Htoon, Han [Los Alamos, NM; Vela, Javier [Los Alamos, NM

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  6. Optical Properties of Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Perinetti, U.

    2011-01-01

    This thesis presents different optical experiments performed on semiconductor quantum dots. These structures allow to confine a small number of electrons and holes to a tiny region of space, some nm across. The aim of this work was to study the basic properties of different types of quantum dots

  7. Quantum Dots Coupled to a Superconductor

    DEFF Research Database (Denmark)

    Jellinggaard, Anders Robert

    are tuned electrostatically. This includes tuning the odd occupation of the dot through a quantum phase transition, where it forms a singlet with excitations in the superconductor. We detail the fabrication of these bottom gated devices, which additionally feature ancillary sensor dots connected...

  8. Effect of temperature on quantum dots

    Indian Academy of Sciences (India)

    MAHDI AHMADI BORJI

    2017-07-12

    Jul 12, 2017 ... applications. Quantum dot semiconductor lasers, due to the discrete density of states, low threshold current and temperature dependence, high optical gain and quan- tum efficiency and high modulation speed, ... elastic properties of neighbour materials, lattice mis- match, and geometry of the quantum dot ...

  9. Surround-gated vertical nanowire quantum dots

    NARCIS (Netherlands)

    Van Weert, M.H.M.; Den Heijer, M.; Van Kouwen, M.P.; Algra, R.E.; Bakkers, E.P.A.M.; Kouwenhoven, L.P.; Zwiller, V.

    2010-01-01

    We report voltage dependent photoluminescence experiments on single indium arsenide phosphide (InAsP) quantum dots embedded in vertical surround-gated indium phosphide (InP) nanowires. We show that by tuning the gate voltage, we can access different quantum dot charge states. We study the

  10. Optical studies of capped quantum dots

    NARCIS (Netherlands)

    Wuister, S.F.

    2005-01-01

    This thesis describes the synthesis and spectroscopy of CdSe and CdTe semiconductor quantum dots (QDs). The first chapter gives an introduction into the unique size dependent properties of semiconductor quantum dots. Highly luminescent QDs of CdSe and CdTe were prepared via a high temperature method

  11. Many electron effects in semiconductor quantum dots

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 26; Issue 1. Many electron effects in ... Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as 'artificial atoms' by some, ... Our calculations have been performed in a three-dimensional quantum dot. We have carried out a study of ...

  12. Coherent control of quantum dots

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Lodahl, Peter; Hvam, Jørn Märcher

    In recent years much effort has been devoted to the use of semiconductor quantum dotsystems as building blocks for solid-state-based quantum logic devices. One importantparameter for such devices is the coherence time, which determines the number ofpossible quantum operations. From earlier...... measurements the coherence time of the selfassembledquantum dots (QDs) has been reported to be limited by the spontaneousemission rate at cryogenic temperatures1.In this project we propose to alter the coherence time of QDs by taking advantage of arecent technique on modifying spontaneous emission rates...

  13. Exciton in closed and opened quantum dot

    Directory of Open Access Journals (Sweden)

    M.V.Tkach

    2007-01-01

    Full Text Available The theory of exciton spectrum in spherically symmetric states for the three- shell closed spherical quantum dot is proposed. The evolution of the exciton spectrum while varying the outer well thickness from zero (stationary spectrum of single closed spherical quantum dot to infinity (quasistationary spectrum of a single open spherical quantum dot is investigated. The mechanism of damping (semiwidth of quasistationary states due to the redistribution over the energy levels of probability of exciton location in the space of two inner shells of nanosystem is studied. It is shown that the three shell closed spherical quantum dot of a rather big thickness of the outer well quite sufficiently and exactly reflects the basic properties of the quasistationary exciton spectrum in a single open spherical quantum dot.

  14. Biocompatible Quantum Dots for Biological Applications

    Science.gov (United States)

    Rosenthal, Sandra J.; Chang, Jerry C.; Kovtun, Oleg; McBride, James R.; Tomlinson, Ian D.

    2011-01-01

    Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, sizetunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots. PMID:21276935

  15. Biocompatible quantum dots for biological applications.

    Science.gov (United States)

    Rosenthal, Sandra J; Chang, Jerry C; Kovtun, Oleg; McBride, James R; Tomlinson, Ian D

    2011-01-28

    Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-tunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Hole spin relaxation in quantum dots

    Science.gov (United States)

    Woods, L. M.; Reinecke, T. L.; Kotlyar, R.

    2004-03-01

    We present results for relaxation of the spin of a hole in a cylindrical quantum dot due to acoustic phonon assisted spin flips at low temperatures with an applied magnetic field. The hole dispersion is calculated by numerical diagonalization of the Luttinger Hamiltonian and applying perturbation theory with respect to the magnetic field, and the hole-phonon coupling is described by the Bir-Pikus Hamiltonian. We find that the decoherence time for hole spins for dots ≲20 nm is on the order of 10-8 s. This is several orders smaller than the decoherence time due to phonon assisted processes for electron spins in similar dots and is comparable to the total decoherence time of an electron spin in a quantum dot, which is controlled by the hyperfine interaction with nuclei. We obtain the dependence of the relaxation rate of the hole spin on dot size and hole mass.

  17. Roundtabling Sustainability

    DEFF Research Database (Denmark)

    Ponte, Stefano

    2014-01-01

    The willingness of public authority to delegate social and environmental regulation to the private sector has varied from sector to sector, but has often led to the establishment of ‘voluntary’ standards and certifications on sustainability. Many of these have taken the form of ‘stewardship...... councils’ and ‘sustainability roundtables’ and have been designed around a set of institutional features seeking to establish legitimacy, fend off possible criticism, and ‘sell’ certifications to potential users. The concept of ‘roundtabling’ emphasizes the fitting a variety of commodity......-specific sustainability situations into a form that not only ‘hears more voices’ (as in ‘multi-stakeholder’), but also portrays to give them equal standing at the table of negotiations (roundtable), thus raising higher expectations on accountability, transparency and inclusiveness. In this article, I examine to what...

  18. Attentional Bias for Threat in Older Adults: Moderation of the Positivity Bias by Trait Anxiety and Stimulus Modality

    OpenAIRE

    Lee, Lewina O.; Knight, Bob G.

    2009-01-01

    Socioemotional selectivity theory suggests that emotion regulation goals motivate older adults to preferentially allocate attention to positive stimuli and away from negative stimuli. This study examined whether anxiety moderates the effect of the positivity bias on attention for threat. We employed the dot probe task to compare subliminal and supraliminal attention for threat in 103 young and 44 older adults. Regardless of anxiety, older but not younger adults demonstrated a vigilant-avoidan...

  19. Sustainability Evaluation.

    Science.gov (United States)

    Stichnothe, Heinz

    2017-03-17

    The long-term substitution of fossil resources can only be achieved through a bio-based economy, with biorefineries and bio-based products playing a major role. However, it is important to assess the implications of the transition to a bio-based economy. Life cycle-based sustainability assessment is probably the most suitable approach to quantify impacts and to identify trade-offs at multiple levels. The extended utilisation of biomass can cause land use change and affect food security of the most vulnerable people throughout the world. Although this is mainly a political issue and governments should be responsible, the responsibility is shifted to companies producing biofuels and other bio-based products. Organic wastes and lignocellulosic biomass are considered to be the preferred feedstock for the production of bio-based products. However, it is unlikely that a bio-based economy can rely only on organic wastes and lignocellulosic biomass.It is crucial to identify potential problems related to socio-economic and environmental issues. Currently there are many approaches to the sustainability of bio-based products, both quantitative and qualitative. However, results of different calculation methods are not necessarily comparable and can cause confusion among decision-makers, stakeholders and the public.Hence, a harmonised, globally agreed approach would be the best solution to secure sustainable biomass/biofuels/bio-based chemicals production and trade, and to avoid indirect effects (e.g. indirect land use change). However, there is still a long way to go.Generally, the selection of suitable indicators that serve the purpose of sustainability assessment is very context-specific. Therefore, it is recommended to use a flexible and modular approach that can be adapted to various purposes. A conceptual model for the selection of sustainability indicators is provided that facilitates identifying suitable sustainability indicators based on relevance and significance in a

  20. Ultrathin (<1??m) Substrate-Free Flexible Photodetector on Quantum Dot-Nanocellulose Paper

    OpenAIRE

    Jingda Wu; Lin, Lih Y.

    2017-01-01

    Conventional approaches to flexible optoelectronic devices typically require depositing the active materials on external substrates. This is mostly due to the weak bonding between individual molecules or nanocrystals in the active materials, which prevents sustaining a freestanding thin film. Herein we demonstrate an ultrathin freestanding ZnO quantum dot (QD) active layer with nanocellulose structuring, and its corresponding device fabrication method to achieve substrate-free flexible optoel...

  1. Cognitive bias measurement and social anxiety disorder: Correlating self-report data and attentional bias

    Directory of Open Access Journals (Sweden)

    Alexander Miloff

    2015-09-01

    Full Text Available Social anxiety disorder (SAD and attentional bias are theoretically connected in cognitive behavioral therapeutic models. In fact, there is an emerging field focusing on modifying attentional bias as a stand-alone treatment. However, it is unclear to what degree these attentional biases are present before commencing treatment. The purpose of this study was to measure pre-treatment attentional bias in 153 participants diagnosed with SAD using a home-based Internet version of the dot-probe paradigm. Results showed no significant correlation for attentional bias (towards or away from negative words or faces and the self-rated version of the Liebowitz Social Anxiety Scale (LSAS-SR. However, two positive correlations were found for the secondary measures Generalized Anxiety Disorder 7 (GAD-7 and Patient Health Questionnaire 9 (PHQ-9. These indicated that those with elevated levels of anxiety and depression had a higher bias towards negative faces in neutral–negative and positive–negative valence combinations, respectively. The unreliability of the dot-probe paradigm and home-based Internet delivery are discussed to explain the lack of correlations between LSAS-SR and attentional bias. Changes to the dot-probe task are suggested that could improve reliability.

  2. Unmasking the Attentional Blink

    Science.gov (United States)

    Nieuwenstein, Mark R.; Potter, Mary C.; Theeuwes, Jan

    2009-01-01

    When asked to identify 2 visual targets (T1 and T2 for the 1st and 2nd targets, respectively) embedded in a sequence of distractors, observers will often fail to identify T2 when it appears within 200-500 ms of T1--an effect called the "attentional blink". Recent work shows that attention does not blink when the task is to encode a…

  3. Managing Sustainability in Management Education

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    2014-01-01

    concerning trade-offs and complexity. Thus, the paper proposes an approach to sustainability in management education which help to initiate such critical reflection and discussion by drawing attention to the complex network of relations in which a given business or industry is embedded.......Sustainability has until relatively recently been seen as irrelevant to business practice and, hence, has been largely missing from management education. But, environmental issues are increasingly becoming a key business concern at local, national, international and global levels. This conceptual...... paper addresses the question: How can sustainability be addresses within management education? It engages in a critical discussion of traditional models for teaching sustainability and Corporate Social Responsibility (CSR) in order to develop an advanced framework that addresses the limitations...

  4. The social sustainability of entrepreneurship

    DEFF Research Database (Denmark)

    Bjerregaard, Toke; Lauring, Jakob

    2012-01-01

    Sustainable entrepreneurship is attracting increasing attention in entrepreneurship literature. Social sustainable entrepreneurship is often conceived as entrepreneurial processes that generate social value. In this chapter we illuminate how small business entrepreneurs in a developing country...... engage in activities of importance for social sustainability and development as they undertake entrepreneurial ventures. We present the findings from an ethnographic field study that examines the strategies used by small entrepreneurs in an area of extreme resource scarcity to navigate co-existing social...... and market logics. The cases elucidate how the entrepreneurs cope with and exploit such co-existing logics through their sphere-straddling ventures to ensure sustainability during changes from an economy based on traditional exchange relationships to a situation with an emerging market economy. The chapter...

  5. Cognition, emotion, and attention.

    Science.gov (United States)

    Müller-Oehring, Eva M; Schulte, Tilman

    2014-01-01

    Deficits of attention, emotion, and cognition occur in individuals with alcohol abuse and addiction. This review elucidates the concepts of attention, emotion, and cognition and references research on the underlying neural networks and their compromise in alcohol use disorder. Neuroimaging research on adolescents with family history of alcoholism contributes to the understanding of pre-existing brain structural conditions and characterization of cognition and attention processes in high-risk individuals. Attention and cognition interact with other brain functions, including perceptual selection, salience, emotion, reward, and memory, through interconnected neural networks. Recent research reports compromised microstructural and functional network connectivity in alcoholism, which can have an effect on the dynamic tuning between brain systems, e.g., the frontally based executive control system, the limbic emotion system, and the midbrain-striatal reward system, thereby impeding cognitive flexibility and behavioral adaptation to changing environments. Finally, we introduce concepts of functional compensation, the capacity to generate attentional resources for performance enhancement, and brain structure recovery with abstinence. An understanding of the neural mechanisms of attention, emotion, and cognition will likely provide the basis for better treatment strategies for developing skills that enhance alcoholism therapy adherence and quality of life, and reduce the propensity for relapse. © 2014 Elsevier B.V. All rights reserved.

  6. Attention deficits and divorce.

    Science.gov (United States)

    Bouchard, Geneviève; Saint-Aubin, Jean

    2014-09-01

    Building on previous work on the role of attention deficits associated with the regulation of executive control in psychiatric disorders, we examine whether these attention deficits are related to an interpersonal disturbance, the experience of divorce. Attentional capacities of 95 randomly selected couples from the general population were measured with a well-established task, the Attentional Network Task, which assesses the efficiency of 3 attention networks (that is, alerting, orienting, and executive control). Among the 190 participants, 32 had experienced a divorce in the past. ANCOVAs were used to compare divorced people in marital or cohabiting unions with people in first unions in their performance on this purely cognitive task. Our findings indicate that divorced people who are currently living in a cohabiting relationship show significantly lower executive control than other adults living as couples, after controlling for sex, age, income, and education. This subgroup of divorced people not only exhibit greater difficulty in responding to some stimuli while ignoring irrelevant ones but also manifest cognitive deficits in conflict resolution. This study highlights the links between attention and the long-term maintenance of intimate relationships. Our results may have important implications for the identification of people at risk for divorce.

  7. Electron transport in quantum dots

    CERN Document Server

    2003-01-01

    When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the...

  8. Chiral quantum dot based materials

    Science.gov (United States)

    Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii

    2014-05-01

    Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.

  9. Quantum dots: lasers and amplifiers

    CERN Document Server

    Bimberg, D

    2003-01-01

    Continuous wave room-temperature output power of approx 3 W for edge emitters and of 1.2 mW for vertical-cavity surface-emitting lasers is realized for GaAs-based devices using InAs quantum dots (QDs) operating at 1.3 mu m. Characteristic temperatures up to 170 K below 330 K are realized. Simultaneously, differential efficiency exceeds 80% for these devices. Lasers emitting up to 12 W at 1140-1160 nm are useful as pump sources for Tm sup 3 sup + -doped fibres for frequency up-conversion to 470 nm. Both types of lasers show transparency current densities of 6 A cm sup - sup 2 per dot layer, eta sub i sub n sub t = 98% and alpha sub i around 1.5 cm sup - sup 1. Long operation lifetimes (above 3000 h at 50 deg C heatsink temperature at 1.5 W CW) and improved radiation hardness as compared to quantum well (QW) devices are manifested. Cut-off frequencies of about 10 GHz at 1100 nm and 6 GHz at 1300 nm and low alpha factors resulting in reduced filamentation and improved M sup 2 values in single-mode operation are ...

  10. Sustainable Land Use Requires Attention to Ecological Signals

    Science.gov (United States)

    Halvorson, W.L.; Castellanos, A.E.; Murrieta-Saldivar, J.

    2003-01-01

    This case study details the difficulties of landscape management, highlighting the challenges inherent in managing natural resources when multiple agencies are involved, when the land users have no incentive for conservation, and when government agencies have too few resources for effective management. Pumping of groundwater from the aquifer of La Costa de Hermosillo in the state of Sonora, Mexico, began in 1945 and developed so quickly that by the late 1950s salinity intrusion from the Gulf of California was occurring in the wells. In the 1970s, the irrigatable land in La Costa peaked at 132,516 ha and the extracted volume of water from the aquifer peaked at around 1.14 billion cubic meters annually. By the 1980s, 105 wells of the total of 498 were contaminated with seawater and, therefore, identified for closure. At present La Costa de Hermosillo still represents 15% of the total harvested land, 16% of the total annual production, and 23% of the gross agricultural production of the state of Sonora. However, there are approximately 80,000 ha of abandoned fields due to salt water intension, lack of water and/or lack of credit available to individual farmers. This unstable situation resulted from the interplay of water management policies and practices, and farm-land policies and practices. While government agencies have been able to enforce better water use for agricultural production, there remains a significant area that requires restoration from its degraded state. For this piece of the ecosystem management puzzle, government agencies have thus far been unable to affect a solution.

  11. Sustainability and Risk Disclosure: An Exploratory Study on Sustainability Reports

    Directory of Open Access Journals (Sweden)

    Elisa Truant

    2017-04-01

    Full Text Available Recent policy changes in sustainability reporting, such as the ones related to the new European Directive on non-financial disclosure (2014/95/EU, the standards issued by the American Sustainability Accounting Standard Board (SASB, the G4 guidelines issued by the Global Sustainability Standard Board (GSSB, and the framework of the International Integrated Reporting Council (IIRC stress the importance of extending the disclosure of ethical, social, and environmental risks within financial and social-environmental reporting. Institutional pressure has notably increased among organizations, in setting up risk management tools to understand sustainability risks within managerial and reporting practices. Given such institutional pressure, the corporate reaction in providing additional sustainability risk disclosure calls for attention and scrutiny. Therefore, this study aims at addressing such issues from an exploratory perspective. We based our analysis on a sample of large Italian organizations that issued sustainability disclosure in accordance with the Global Reporting Initiative (GRI, G4 guidelines, and we tested the relationship between their level of risk disclosure and other relevant variables. Consistently with the literature, we found that “experienced” sustainable reporters provide a significant volume of disclosure, and that disclosure quality on risk is positively influenced by their international presence and reporting experience. However, when accounting for specific risk-related areas of disclosure, only a few of them seem to adopt a managerial perspective linking strategy, risk metrics, and disclosure.

  12. Peptide dot immunoassay and immunoblotting: electroblotting from aluminum thin-layer chromatography plates and isoelectric focusing gels to activated nitrocellulose

    DEFF Research Database (Denmark)

    Bjerrum, O.J.; Holm, A.; Lauritzen, Edgar

    1993-01-01

    Peptide dot immunoassay, electroblotting, activated nitrocellulose, dot blot, membranes, peptides and proteins......Peptide dot immunoassay, electroblotting, activated nitrocellulose, dot blot, membranes, peptides and proteins...

  13. Sustainable Soesterkwartier

    NARCIS (Netherlands)

    Abrahams, H.; Goosen, H.; Jong, de F.; Sickmann, J.; Prins, D.

    2010-01-01

    The municipality of Amersfoort wants to construct an endurable and sustainable eco-town in the Soesterkwartier neighbourhood, by taking future climate change into account. The impact of climate change at the location of the proposed eco-town was studied by a literature review.

  14. Sustainable agriculture

    International Development Research Centre (IDRC) Digital Library (Canada)

    New farming techniques, better food security. Since 1970, IDRC-supported research has introduced sustainable agricultural practices to farmers and communities across the devel- oping world. The result: higher productivity, less poverty, greater food security, and a healthier environment. Opportunities grow on trees in ...

  15. Sustainable Development

    African Journals Online (AJOL)

    Tsegai Berhane Ghebretekle

    Abstract. This article examines the concept of sustainable development after the Post-. 2015 Paris Climate Change Agreement with particular emphasis on Ethiopia. Various African countries are vulnerable to climate change, as is evidenced by recent droughts. Ethiopia is selected as a case study in light of its pace in.

  16. Sustainable machining

    CERN Document Server

    2017-01-01

    This book provides an overview on current sustainable machining. Its chapters cover the concept in economic, social and environmental dimensions. It provides the reader with proper ways to handle several pollutants produced during the machining process. The book is useful on both undergraduate and postgraduate levels and it is of interest to all those working with manufacturing and machining technology.

  17. Architecture Sustainability

    NARCIS (Netherlands)

    Avgeriou, Paris; Stal, Michael; Hilliard, Rich

    2013-01-01

    Software architecture is the foundation of software system development, encompassing a system's architects' and stakeholders' strategic decisions. A special issue of IEEE Software is intended to raise awareness of architecture sustainability issues and increase interest and work in the area. The

  18. Sustainability reporting

    NARCIS (Netherlands)

    Kolk, A.

    2005-01-01

    This article gives an overview of developments in sustainability (also sometimes labelled corporate social responsibility) reporting. It The article will first briefly indicate how accountability on social and environmental issues started, already in the 1970s when social reports were published.

  19. Exergy sustainability.

    Energy Technology Data Exchange (ETDEWEB)

    Robinett, Rush D. III (.; ); Wilson, David Gerald; Reed, Alfred W.

    2006-05-01

    Exergy is the elixir of life. Exergy is that portion of energy available to do work. Elixir is defined as a substance held capable of prolonging life indefinitely, which implies sustainability of life. In terms of mathematics and engineering, exergy sustainability is defined as the continuous compensation of irreversible entropy production in an open system with an impedance and capacity-matched persistent exergy source. Irreversible and nonequilibrium thermodynamic concepts are combined with self-organizing systems theories as well as nonlinear control and stability analyses to explain this definition. In particular, this paper provides a missing link in the analysis of self-organizing systems: a tie between irreversible thermodynamics and Hamiltonian systems. As a result of this work, the concept of ''on the edge of chaos'' is formulated as a set of necessary and sufficient conditions for stability and performance of sustainable systems. This interplay between exergy rate and irreversible entropy production rate can be described as Yin and Yang control: the dialectic synthesis of opposing power flows. In addition, exergy is shown to be a fundamental driver and necessary input for sustainable systems, since exergy input in the form of power is a single point of failure for self-organizing, adaptable systems.

  20. Sustainable processing

    DEFF Research Database (Denmark)

    Kristensen, Niels Heine

    2004-01-01

    Kristensen_NH and_Beck A: Sustainable processing. In Otto Schmid, Alexander Beck and Ursula Kretzschmar (Editors) (2004): Underlying Principles in Organic and "Low-Input Food" Processing - Literature Survey. Research Institute of Organic Agriculture FiBL, CH-5070 Frick, Switzerland. ISBN 3-906081-58-3...

  1. Sustainable finance

    NARCIS (Netherlands)

    dr. Margreet F. Boersma-de Jong

    2012-01-01

    Presentation for Springschool of Strategy, University of Groningen, 10 October 2012. The role of CSR is to stimulate ethical behaviour, and as a result, mutual trust in society. Advantage of CSR for the company and the evolution of CSR. From CSR to Sustainable Finance: how does CSR influence

  2. Kennedy Space Center Five Year Sustainability Plan

    Science.gov (United States)

    Williams, Ann T.

    2016-01-01

    The Federal Government is committed to following sustainable principles. At its heart, sustainability integrates environmental, societal and economic solutions for present needs without compromising the ability of future generations to meet their needs. Building upon its pledge towards environmental stewardship, the Administration generated a vision of sustainability spanning ten goals mandated within Executive Order (EO) 13693, Planning for Federal Sustainability in the Next Decade. In November 2015, the National Aeronautics and Space Administration (NASA) responded to this EO by incorporating it into a new release of the NASA Strategic Sustainability Performance Plan (SSPP). The SSPP recognizes the importance of aligning environmental practices in a manner that preserves, enhances and strengthens NASA's ability to perform its mission indefinitely. The Kennedy Space Center (KSC) is following suit with KSC's Sustainability Plan (SP) by promoting, maintaining and pioneering green practices in all aspects of our mission. KSC's SP recognizes that the best sustainable solutions use an interdisciplinary, collaborative approach spanning civil servant and contractor personnel from across the Center. This approach relies on the participation of all employees to develop and implement sustainability endeavors connected with the following ten goals: Reduce greenhouse gas (GHG) emissions. Design, build and maintain sustainable buildings, facilities and infrastructure. Leverage clean and renewable energy. Increase water conservation. Improve fleet and vehicle efficiency and management. Purchase sustainable products and services. Minimize waste and prevent pollution. Implement performance contracts for Federal buildings. Manage electronic equipment and data centers responsibly. Pursue climate change resilience. The KSC SP details the strategies and actions that address the following objectives: Reduce Center costs. center dot Increase energy and water efficiencies. Promote smart

  3. Inter-dot coupling effects on transport through correlated parallel ...

    Indian Academy of Sciences (India)

    Transport through symmetric parallel coupled quantum dot system has been studied, using non-equilibrium Green function formalism. The inter-dot tunnelling with on-dot and inter-dot Coulomb repulsion is included. The transmission coefficient and Landaur–Buttiker like current formula are shown in terms of internal states ...

  4. A pattern of test findings predicting attention problems at school.

    Science.gov (United States)

    Korkman, M; Peltomaa, K

    1991-08-01

    The aim of this study was to identify different types of neuropsychological test profiles that would predict attention problems at school. Forty-six children with mild developmental disorders, among whom a high frequency of attention deficit disorder (ADD) was expected, were examined just before they started school. The tests were mainly drawn from a new assessment, called NEPSY, and corresponded to the various components of attention. The test profiles were grouped with the aid of a Q-type factor analysis into five subgroups. The test profiles of two of the subgroups were suggestive of attention deficits. The predictions were based on difficulties in tests aimed to evaluate impulse control, sustained attention, and selective attention. As such findings were found in both of the subgroups they were collapsed into one. Half a year later the collapsed subgroups were found to have a higher frequency of attention problems at school than the other three subgroups.

  5. How motivation and reward learning modulate selective attention.

    Science.gov (United States)

    Bourgeois, A; Chelazzi, L; Vuilleumier, P

    2016-01-01

    Motivational stimuli such as rewards elicit adaptive responses and influence various cognitive functions. Notably, increasing evidence suggests that stimuli with particular motivational values can strongly shape perception and attention. These effects resemble both selective top-down and stimulus-driven attentional orienting, as they depend on internal states but arise without conscious will, yet they seem to reflect attentional systems that are functionally and anatomically distinct from those classically associated with frontoparietal cortical networks in the brain. Recent research in human and nonhuman primates has begun to reveal how reward can bias attentional selection, and where within the cognitive system the signals providing attentional priority are generated. This review aims at describing the different mechanisms sustaining motivational attention, their impact on different behavioral tasks, and current knowledge concerning the neural networks governing the integration of motivational influences on attentional behavior. © 2016 Elsevier B.V. All rights reserved.

  6. Connectivity supporting attention in children with attention deficit hyperactivity disorder

    Directory of Open Access Journals (Sweden)

    Anita D. Barber

    2015-01-01

    While CON–DMN anti-correlation is associated with improved attention in ADHD, other circuitry supports improved attention in TD children. Greater CON–DMN anti-correlation supported better attentional control in children with ADHD, but worse attentional control in TD children. On the other hand, greater DMN–occipital anti-correlation supported better attentional control in TD children.

  7. Effects of a structured 20-session slow-cortical-potential-based neurofeedback program on attentional performance in children and adolescents with attention-deficit hyperactivity disorder: retrospective analysis of an open-label pilot-approach and 6-month follow-up

    Directory of Open Access Journals (Sweden)

    Albrecht JS

    2017-03-01

    Full Text Available Johanna S Albrecht,1–3 Sarah Bubenzer-Busch,1,2 Anne Gallien,1,4 Eva Lotte Knospe,1,2 Tilman J Gaber,1,2,5 Florian D Zepf1,2,6,7 1Clinic for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, Aachen, 2JARA Translational Brain Medicine, Aachen & Jülich, 3Center for Pediatrics and Adolescent Medicine Elisabeth Hospital Rheydt, Mönchengladbach, 4Clinic for Neurology, Medical Center City Region Aachen, Würselen, 5NeuroCare Group, Munich, Germany; 6Centre and Discipline of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, School of Paediatrics and Child Health & School of Psychiatry and Clinical Neurosciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia, 7Department of Health in Western Australia, Specialised Child and Adolescent Mental Health Services, Perth, WA, Australia Objective: The aim of this approach was to conduct a structured electroencephalography-based neurofeedback training program for children and adolescents with attention-deficit hyperactivity disorder (ADHD using slow cortical potentials with an intensive first (almost daily sessions and second phase of training (two sessions per week and to assess aspects of attentional performance. Patients and methods: A total of 24 young patients with ADHD participated in the 20-session training program. During phase I of training (2 weeks, 10 sessions, participants were trained on weekdays. During phase II, neurofeedback training occurred twice per week (5 weeks. The patients’ inattention problems were measured at three assessment time points before (pre, T0 and after (post, T1 the training and at a 6-month follow-up (T2; the assessments included neuropsychological tests (Alertness and Divided Attention subtests of the Test for Attentional Performance; Sustained Attention Dots and Shifting Attentional Set subtests of the Amsterdam Neuropsychological Test and questionnaire data

  8. Attention and reading skills.

    Science.gov (United States)

    Commodari, Elena; Guarnera, Maria

    2005-04-01

    Attention plays a critical role in information processing. Its adequate functioning is required for correct development of complex cognitive abilities and regular scholastic progress. Children with attention deficits often have difficulties in reading, writing, and arithmetic. The present study investigated interactions among reading skills, overall scholastic performance as rated by teachers, and components of attention: visual reaction time, simple immediate span of attention, and selectivity. The sample was 98 students in the first and second years of public junior high school (age range 11-14 years, M = 12.6, SD = 1.2), i.e., with expected already well-established reading. Reading was evaluated using Comprehension, Accuracy, and Speed tests. Overall scholastic performance was obtained by means of teachers' ratings. Simple Reaction Time, Digit Span, and Color-Word Interference, included in a multitask computerized test, assessed attention. Analysis confirmed the hypothesis that the reading skills are strongly predictive of the Scholastic Assessment rated by the teachers. High scholastic ratings were correlated with Reading Speed and Accuracy rather than Reading Comprehension. Poor readers showed worse performances on the Digit Span test which measures simple immediate span of attention. Good and poor readers obtained a similar score on the Color-Word Interference task. This observation seems to contrast with the more common interpretation of this effect, suggesting that reading is an automatic process and, therefore, the semantic dimension overcomes the controlled perceptual one. According to other studies, an alternative explanation is suggested. In conclusion, present results confirm the hypothesis of a strong link among reading speed and accuracy, scholastic assessment as rated by teachers, simple immediate span of attention, and visual reaction time.

  9. Empirical Recommendations for Improving the Stability of the Dot-Probe Task in Clinical Research

    Science.gov (United States)

    Price, Rebecca B.; Kuckertz, Jennie M.; Siegle, Greg J.; Ladouceur, Cecile D.; Silk, Jennifer S.; Ryan, Neal D.; Dahl, Ronald E.; Amir, Nader

    2014-01-01

    The dot-probe task has been widely used in research to produce an index of biased attention based on reaction times (RTs). Despite its popularity, very few published studies have examined psychometric properties of the task, including test-retest reliability, and no previous study has examined reliability in clinically anxious samples or systematically explored the effects of task design and analysis decisions on reliability. In the current analysis, we utilized dot-probe data from three studies where attention bias towards threat-related faces was assessed at multiple (≥5) timepoints. Two of the studies were similar (adults with Social Anxiety Disorder, similar design features) while one was much more disparate (pediatric healthy volunteers, distinct task design). We explored the effects of analysis choices (e.g., bias score calculation formula, methods for outlier handling) on reliability and searched for convergence of findings across the three studies. We found that, when considering the three studies concurrently, the most reliable RT bias index utilized data from dot-bottom trials, comparing congruent to incongruent trials, with rescaled outliers, particularly after averaging across more than one assessment point. Although reliability of RT bias indices was moderate to low under most circumstances, within-session variability in bias (attention bias variability; ABV), a recently proposed RT index, was more reliable across sessions. Several eyetracking-based indices of attention bias (available in the pediatric healthy sample only) showed reliability that matched the optimal RT index (ABV). On the basis of these findings, we make specific recommendations to researchers using the dot probe, particularly those wishing to investigate individual differences and/or single-patient applications. PMID:25419646

  10. Quantum dots with single-atom precision.

    Science.gov (United States)

    Fölsch, Stefan; Martínez-Blanco, Jesús; Yang, Jianshu; Kanisawa, Kiyoshi; Erwin, Steven C

    2014-07-01

    Quantum dots are often called artificial atoms because, like real atoms, they confine electrons to quantized states with discrete energies. However, although real atoms are identical, most quantum dots comprise hundreds or thousands of atoms, with inevitable variations in size and shape and, consequently, unavoidable variability in their wavefunctions and energies. Electrostatic gates can be used to mitigate these variations by adjusting the electron energy levels, but the more ambitious goal of creating quantum dots with intrinsically digital fidelity by eliminating statistical variations in their size, shape and arrangement remains elusive. We used a scanning tunnelling microscope to create quantum dots with identical, deterministic sizes. By using the lattice of a reconstructed semiconductor surface to fix the position of each atom, we controlled the shape and location of the dots with effectively zero error. This allowed us to construct quantum dot molecules whose coupling has no intrinsic variation but could nonetheless be tuned with arbitrary precision over a wide range. Digital fidelity opens the door to quantum dot architectures free of intrinsic broadening-an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies of confined electrons.

  11. Modelling auditory attention.

    Science.gov (United States)

    Kaya, Emine Merve; Elhilali, Mounya

    2017-02-19

    Sounds in everyday life seldom appear in isolation. Both humans and machines are constantly flooded with a cacophony of sounds that need to be sorted through and scoured for relevant information-a phenomenon referred to as the 'cocktail party problem'. A key component in parsing acoustic scenes is the role of attention, which mediates perception and behaviour by focusing both sensory and cognitive resources on pertinent information in the stimulus space. The current article provides a review of modelling studies of auditory attention. The review highlights how the term attention refers to a multitude of behavioural and cognitive processes that can shape sensory processing. Attention can be modulated by 'bottom-up' sensory-driven factors, as well as 'top-down' task-specific goals, expectations and learned schemas. Essentially, it acts as a selection process or processes that focus both sensory and cognitive resources on the most relevant events in the soundscape; with relevance being dictated by the stimulus itself (e.g. a loud explosion) or by a task at hand (e.g. listen to announcements in a busy airport). Recent computational models of auditory attention provide key insights into its role in facilitating perception in cluttered auditory scenes.This article is part of the themed issue 'Auditory and visual scene analysis'. © 2017 The Authors.

  12. Investigation on DOT guided FMT: Whether the FMT image quality is robust to the priori DOT information?

    Science.gov (United States)

    Wang, Daifa; Bai, Jing

    2009-01-01

    The fluorescence molecular tomography (FMT) image quality could be improved significantly with reconstructed optical properties using diffuse optical tomography (DOT). However, different DOT algorithms and different constraint parameters usually lead to DOT images of obvious different image quality. In this paper, simulation experiment results demonstrate that the FMT image quality is robust to the great variation in DOT image quality.

  13. X-H{center_dot}{center_dot}{center_dot}{pi} and X-H{center_dot}{center_dot}{center_dot}N hydrogen bonds - Acetylene and hydrogen cyanide as proton acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Domagala, Malgorzata, E-mail: mdomagala@uni.lodz.pl [Department of Chemistry, University of Lodz, ul.Pomorska 149/153, 90-236 Lodz (Poland); Grabowski, Slawomir J., E-mail: slagra@uni.lodz.pl [Department of Chemistry, University of Lodz, ul.Pomorska 149/153, 90-236 Lodz (Poland)

    2009-09-18

    The hydrogen-bonded systems were considered where acetylene or hydrogen cyanide acts as a proton acceptor and different proton donating molecules are taken into account. The B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) calculations were performed for the systems considered; for HCN{center_dot}{center_dot}{center_dot}HF and C{sub 2}H{sub 2}{center_dot}{center_dot}{center_dot}HF complexes various levels of approximation were applied up to CCSD(T)/6-311++G(3df,3pd)//CCSD/6-311++G(3df,3pd). The Quantum Theory of 'Atoms in Molecules' (QTAIM) was also applied. It was found that {pi}-electrons of acetylene might act as the proton accepting centers and the found complex conformations are T-shaped ones. For hydrogen cyanide molecule the nitrogen atom acts as the proton acceptor center but not {pi}-electrons. The characteristics of the bond critical points were also considered for the analyzed interactions and numerous correlations were found between geometrical, energetic and QTAIM parameters. The decomposition of the interaction energy for the systems analyzed was also applied.

  14. SUSTAINABLE CORPORATE AND SUSTAINABLE DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    DORU CÎRNU

    2017-06-01

    Full Text Available In recent decades, the image of the international business environment has changed significantly. Studies conducted by UNCTAD shows that corporate phenomenon developments in the world economy is growing. Without claiming to present an exhaustive topic so vast we tried to capture some "facets" of sustainable development from the perspective of multinational corporations, given the expansion of these economic entities and strengthening their power in the global economy. We present more negative aspects of the actions of multinational corporations in terms of sustainable development, it is very important to know both sides of the coin, which will not only help transnational giants including release. Based on issues such as corporate social responsibility, environmental pollution and workers' rights, we sought to counter official statements. The conclusion is that these economic entities are real forces that can not be ignored in today's world and the obvious problem of sustainable development can not be addressed independently of the phenomenon, context we also identified some possible solutions to conflict of corporations and essence of the concept of sustainable development.

  15. Moment of inertia in elliptical quantum dots

    Science.gov (United States)

    Serra, Llorenç; Puente, Antonio; Lipparini, Enrico

    The moment of inertia of deformed quantum dots and its experimental relevance in relation to the dot spectroscopic features is theoretically investigated. A strong link to the low-energy orbital current mode that manifests in the magnetic dipole (M1) spectrum is stressed. The moment of inertia is obtained by solving the cranked Kohn-Sham equations within the local-spin-density approximation and the results discussed in comparison with the predictions of an analytical non-interacting model. The results as a function of deformation and size indicate that the existence of spin transitions in the dot ground state has an important effect on the moment of inertia.

  16. Odd triplet superconductivity in ultrasmall quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Stephan; Koenig, Juergen [Theoretische Physik, Universitaet Duisburg-Essen and CENIDE (Germany); Sothmann, Bjoern [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany)

    2016-07-01

    We report on the possibility to create odd frequency Cooper pairs in proximized interacting quantum dots attached to ferromagnetic leads. Spin blockade effects together with induced superconductivity allow electron pairs with same spin at different times to carry superconducting correlations. Besides the conventional finite singlet pairing amplitude on the dot, only odd frequency triplet pairing is possible here. This is in contrast to the double dot case. We demonstrate how the order parameter for odd-frequency triplet pairing as well as the differential Andreev conductance are influenced when tuning gate and/or bias voltages, the angle of magnetizations of the leads and the coupling to the nearby superconductor.

  17. Excitonic quasimolecules in nanosystems of quantum dots

    Science.gov (United States)

    Pokutnyi, Sergey I.

    2017-09-01

    The theory of excitonic quasimolecules (biexcitons) (formed of spatially separated electrons and holes) in a nanosystem that consists of semiconductor quantum dots synthesized in a borosilicate glass matrix is presented. It is shown that exciton quasimolecule formation is of a threshold character and is possible in nanosystem, if the spacing between the quantum dots surfaces is larger than a certain critical spacing. It was found that the binding energy of the singlet ground state of an exciton quasimolecule, consisting of two semiconductor quantum dots is a significant large values, larger than the binding energy of the biexciton in a semiconductor single crystal by almost two orders of magnitude.

  18. Fluorescent Quantum Dots for Biological Labeling

    Science.gov (United States)

    McDonald, Gene; Nadeau, Jay; Nealson, Kenneth; Storrie-Lomardi, Michael; Bhartia, Rohit

    2003-01-01

    Fluorescent semiconductor quantum dots that can serve as "on/off" labels for bacteria and other living cells are undergoing development. The "on/off" characterization of these quantum dots refers to the fact that, when properly designed and manufactured, they do not fluoresce until and unless they come into contact with viable cells of biological species that one seeks to detect. In comparison with prior fluorescence-based means of detecting biological species, fluorescent quantum dots show promise for greater speed, less complexity, greater sensitivity, and greater selectivity for species of interest. There are numerous potential applications in medicine, environmental monitoring, and detection of bioterrorism.

  19. Analysis list: DOT1L [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DOT1L Pluripotent stem cell + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/DOT1...L.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/DOT1L.5.tsv http://dbarchive.biosc...iencedbc.jp/kyushu-u/hg19/target/DOT1L.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/DOT1L.Plu

  20. Parallel carbon nanotube quantum dots and their interactions

    OpenAIRE

    Goss K.; Leijnse M.; Smerat S.; Wegewijs M.R.; Schneider C.M.; Meyer C

    2012-01-01

    We present quantum transport measurements of interacting parallel quantum dots formed in the strands of a carbon nanotube rope. In this molecular quantum dot system, transport is dominated by one quantum dot, while additional resonances from parallel side dots appear, which exhibit a weak gate coupling. This differential gating effect provides a tunability of the quantum dot system with only one gate electrode and provides control over the carbon nanotube strand that carries the current. By t...

  1. Scanning gate microscopy of ultra clean carbon nanotube quantum dots

    OpenAIRE

    Xue, Jiamin; Dhall, Rohan; Cronin, Stephen B.; LeRoy, Brian J.

    2015-01-01

    We perform scanning gate microscopy on individual suspended carbon nanotube quantum dots. The size and position of the quantum dots can be visually identified from the concentric high conductance rings. For the ultra clean devices used in this study, two new effects are clearly identified. Electrostatic screening creates non-overlapping multiple sets of Coulomb rings from a single quantum dot. In double quantum dots, by changing the tip voltage, the interactions between the quantum dots can b...

  2. Cognitive Penetration and Attention

    Science.gov (United States)

    Gross, Steven

    2017-01-01

    Zenon Pylyshyn argues that cognitively driven attentional effects do not amount to cognitive penetration of early vision because such effects occur either before or after early vision. Critics object that in fact such effects occur at all levels of perceptual processing. We argue that Pylyshyn’s claim is correct—but not for the reason he emphasizes. Even if his critics are correct that attentional effects are not external to early vision, these effects do not satisfy Pylyshyn’s requirements that the effects be direct and exhibit semantic coherence. In addition, we distinguish our defense from those found in recent work by Raftopoulos and by Firestone and Scholl, argue that attention should not be assimilated to expectation, and discuss alternative characterizations of cognitive penetrability, advocating a kind of pluralism. PMID:28275358

  3. Attention in Urban Foraging

    Directory of Open Access Journals (Sweden)

    Malcolm McCullough

    2013-05-01

    Full Text Available This position paper argues how there has to be much more to smart city learning than just wayshowing, and something better as augmented reality than covering the world with instructions. Attention has become something for many people to know better in an age of information superabundance. Embodied cognition explains how the work-ings of attention are not solely a foreground task, as if attention is something to pay. As digital media appear in ever more formats and contexts, their hybrids with physical form increasing influence how habitual engagement with persistent situations creates learning. Ambient information can just add to the distraction by multitasking, or it can support more favorable processes of shifting among different kinds of information with a particular intent. As one word for this latter process, foraging deserves more consideration in smart city learning

  4. Attention: an evolving construct.

    Science.gov (United States)

    Joyce, Arthur; Hrin, Skip

    2015-01-01

    We review the implications of large-scale brain systems on the construct of attention by first focusing on significant theories and discoveries during the previous 150 years and then considering how the comparatively recent discovery of large-scale brain systems may render previous conceptualizations of attention outdated. Seven functional brain networks are briefly reviewed and the implications of emerging principles of brain functioning for test construction and neuropsychological evaluation are considered. To remain a relevant discipline moving into the 21st century, the field of neuropsychology needs to apply the principles that have been discovered about brain networks to better inform our understanding of attention as well as our ever-refining evaluation of this construct.

  5. Formations of magnetic vortices in a chain array of triangle Py dots and an isosceles triangle Py dot

    Science.gov (United States)

    Miyata, M.; Kiseki, K.; Yakata, S.; Wada, H.; Kimura, T.

    2012-04-01

    We have studied the magnetic domain structures in a magneto-statically-coupled chain array of the triangle dots and an isosceles triangle dot by means of magnetic force microscopy (MFM). Despite the strong magneto-static interaction in the chain array of the dots, each triangle dot takes a single vortex structure. The chirality of each dot is found to behave similarly to that for the isolated triangle dot. We also demonstrated that single-vortex and double-vortex structures with the desired chiralities can be stabilized in an isosceles triangle dot.

  6. Education for Sustainability through a Photography Competition

    Directory of Open Access Journals (Sweden)

    Rowena Scott

    2014-01-01

    Full Text Available This article describes the development and history of a sustainability photography competition. From its simple beginnings as an environmental officer’s idea, an environmental sustainability photography competition began in just one university. Now hosted by Australasian Campuses Towards Sustainability (ACTS, finalist entries are viewed on a public website gaining international attention. A purpose of this article is to demonstrate the diversity of views of sustainability by displaying the winning entries from 2013 and 2012. It is anticipated that readers may replicate these ideas in creative arts and across disciplines throughout primary, secondary and other higher education institutions, community groups and diverse organizations.

  7. Sustainable Tourism in Practice: Promoting or Perverting the Quest for a Sustainable Development?

    Directory of Open Access Journals (Sweden)

    Carlo Aall

    2014-04-01

    Full Text Available Sustainable tourism has achieved the status of being the superior goal in Norwegian government tourism policy, and is attaining much attention in the international scientific and political discourse on tourism. However, have policies on sustainable tourism and related concepts actually managed to make tourism more sustainable? This article seeks to address this question by first presenting the history of sustainable tourism and related concepts, and specifically analyzing how the triple bottom line approach has influenced the prevailing understanding of the concept of sustainable tourism. The article concludes by claiming that prevailing EU as well as Norwegian national policies aiming to make tourism more sustainable most likely will result in “sustaining tourism” more than actually making tourism more sustainable. The article uses Norway—the “home of the Brundtland report”—as an illustrative case for the discussion.

  8. Sustainable Consumption

    DEFF Research Database (Denmark)

    Røpke, Inge

    2015-01-01

    in wider social, economic and technological frameworks is emphasised. In particular, the chapter is inspired by practice theory and transition theory. First, various trends in consumption are outlined to highlight some of the challenges for sustainability transitions. Then, it is discussed how consumption...... patterns are shaped over time and what should be considered in sustainability strategies. While discussions on consumption often take their point of departure in the perspective of the individual and then zoom to the wider context, the present approach is the opposite. The outline starts with the basic...... biophysical, distributional and economic conditions for high consumption in rich countries and then zooms in on the coevolution of provision systems and consumption, and how consumption is shaped by practices and projects in everyday life. Furthermore, the paper discusses whether and how transition...

  9. Sustainable Buildings

    DEFF Research Database (Denmark)

    Tommerup, Henrik M.; Elle, Morten

    The scientific community agrees that: all countries must drastically and rapidly reduce their CO2 emissions and that energy efficient houses play a decisive role in this. The general attitude at the workshop on Sustainable Buildings was that we face large and serious climate change problems that ...... that need urgent action. The built environment is an obvious area to put effort into because of the large and cost-effective energy saving potential and potential for Renewable Energy-based supply systems for buildings.......The scientific community agrees that: all countries must drastically and rapidly reduce their CO2 emissions and that energy efficient houses play a decisive role in this. The general attitude at the workshop on Sustainable Buildings was that we face large and serious climate change problems...

  10. Interventions targeting attention in young children with autism.

    Science.gov (United States)

    Patten, Elena; Watson, Linda R

    2011-02-01

    The ability to focus and sustain one's attention is critical for learning. Children with autism demonstrate unusual characteristics of attention from infancy. It is reasonable to assume that early anomalies in attention influence a child's developmental trajectories. Therapeutic interventions for autism often focus on core features of autism such as communication and socialization, while very few interventions specifically address attention. The purpose of this article is to provide clinicians a description of attention characteristics in children with autism and discuss interventions thought to improve attention. Characteristics of attention in children with autism are presented. Intervention studies featuring measures of attention as an outcome variable for young children with autism are reviewed to present interventions that have empirical evidence for improvements in attention. Results are synthesized by strategy, specific feature of attention targeted, and results for both habilitative goals and accommodations for attention. Although research is not extensive, several strategies to support attention in young children with autism have been investigated. The empirical findings regarding these strategies can inform evidence-based practice.

  11. Thermoelectric transport through quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Merker, Lukas Heinrich

    2016-06-30

    In this thesis the thermoelectric properties (electrical conductance, Seebeck coefficient and thermal conductance)of quantum dots described by the Anderson impurity model have been investigated by using the numerical renormalization group (NRG) method. In order to make accurate calculations for thermoelectric properties of quantum impurity systems, a number of recent developments and refinements of the NRG have been implemented. These include the z-averaging and Campo discretization scheme, which enable the evaluation of physical quantities on an arbitrary temperature grid and at large discretization parameter Λ and the full density matrix (FDM) approach, which allows a more accurate calculation of spectral functions and transport coefficients. The implementation of the z-averaging and Campo discretization scheme has been tested within a new method for specific heats of quantum impurities. The accuracy of this new method was established by comparison with the numerical solution of the Bethe-ansatz equations for the Anderson model. The FDM approach was implemented and tested within a new approach to the calculation of impurity contributions to the uniform susceptibilities. Within this method a non-negligible contribution from the ''environmental'' degrees of freedom needs to be taken into account to recover the correct susceptibility, as shown by comparison with the Bethe-ansatz approach. An accurate method to calculate the conductance of a quantum dot is implemented, enabling the extraction of the Fermi liquid scaling coefficients c{sub T} and c{sub B} to high accuracy, being able to verify the results of the renormalized super perturbation theory approach (within its regime of validity). The method was generalized to higher order moments of the local level spectral function. This, as well as reduction of the SU(2) code to the U(1) symmetry, enabled the investigation of the effect of a magnetic field on the thermoelectric properties of quantum

  12. Visual attention capacity

    DEFF Research Database (Denmark)

    Habekost, Thomas; Starrfelt, Randi

    2009-01-01

    Psychophysical studies have identified two distinct limitations of visual attention capacity: processing speed and apprehension span. Using a simple test, these cognitive factors can be analyzed by Bundesen's Theory of Visual Attention (TVA). The method has strong specificity and sensitivity...... to patient testing, and review existing TVA-based patient studies organized by lesion anatomy. Lesions in three anatomical regions affect visual capacity: The parietal lobes, frontal cortex and basal ganglia, and extrastriate cortex. Visual capacity thus depends on large, bilaterally distributed anatomical...... networks that include several regions outside the visual system. The two visual capacity parameters are functionally separable, but seem to rely on largely overlapping brain areas....

  13. Phonon impact on optical control schemes of quantum dots: Role of quantum dot geometry and symmetry

    Science.gov (United States)

    Lüker, S.; Kuhn, T.; Reiter, D. E.

    2017-12-01

    Phonons strongly influence the optical control of semiconductor quantum dots. When modeling the electron-phonon interaction in several theoretical approaches, the quantum dot geometry is approximated by a spherical structure, though typical self-assembled quantum dots are strongly lens-shaped. By explicitly comparing simulations of a spherical and a lens-shaped dot using a well-established correlation expansion approach, we show that, indeed, lens-shaped dots can be exactly mapped to a spherical geometry when studying the phonon influence on the electronic system. We also give a recipe to reproduce spectral densities from more involved dots by rather simple spherical models. On the other hand, breaking the spherical symmetry has a pronounced impact on the spatiotemporal properties of the phonon dynamics. As an example we show that for a lens-shaped quantum dot, the phonon emission is strongly concentrated along the direction of the smallest axis of the dot, which is important for the use of phonons for the communication between different dots.

  14. A computational model of focused attention meditation and its transfer to a sustained attention task

    NARCIS (Netherlands)

    Moye, Amir Sep; van Vugt, Marieke; van Vugt, Marieke K; Banks, Adrian P; Kennedy, William G

    2017-01-01

    Although meditation and mindfulness practices are widely discussed and studied more and more in the scientific literature, there is little theory about the cognitive mechanisms that comprise it. Here we begin to develop such a theory by creating a computational cognitive model of a particular type

  15. Self-assembly of heterojunction quantum dots(HeQuaDs)

    Science.gov (United States)

    Eyink, K. G.; Tomich, D. H.; Grazulis, L.; Pitz, J. J.; Mahalingam, K.; Shank, J.; Munshi, S.; Ulrich, B.

    2006-02-01

    Quantum dots (QDs) have been receiving considerable attention due to the unique properties, which arise due to the confinement of the electron and holes in a lower band gap material. The InAs on GaAs material system is one of the most studied combinations in which quantum dots form during epitaxy. These QDs form in a Stranski Krastanov manner via a self-assembly process in which the dots nucleate at a critical adatom coverage on a wetting layer of InAs. QDs may be vertically aligned by using the residual strain above a buried dot layer to enhance the nucleation of the second layer of dots. In this work, we show the formation of QDs, which are composed of multiple materials, can be formed through a marriage of these two concepts. In this particular demonstration, we formed InAs dots on GaAs andcrowned the QDs with GaSb and encapsulated the entire structure with GaAs. Atomic Force Microscopy shows additional nucleation between the InAs layers has been minimized and cross-sectional transmission electron microscopy shows the formation the composite structure. Transmission electron microscopy indicated a clear boundary between the GaSb and InAs regions. AFM analysis of the HeQuaD structure shows that GaSb material grows mainly on the two (1 1 0) inclined facets. Thus, the HeQuaD is elongated along the (1 1 0) direction. We have also obtained preliminary photoluminescence (PL) from a 3 layer GaS/InAs HeQuaD structure with a peak around 1.3 microns.

  16. Combination of attentional and spatial working memory deficits in Bálint-Holmes syndrome.

    Science.gov (United States)

    Pisella, Laure; Biotti, Damien; Vighetto, Alain

    2015-03-01

    This study aims to investigate whether attention and spatiotemporal integration deficits are dissociated in patients with bilateral posterior cortical atrophy (PCA), and whether it is their combination that leads to a severe clinical handicap. We recorded performance and ocular behavior of four PCA patients and four age-matched controls in visual search and counting tasks. We measured the percentage of targets detected and the mean detection time in a "pop-out" search. We also compared counting ability when a set of dots is presented briefly (in healthy individuals, the automatic deployment of attention over space allows a fast estimation of quantity) or for unlimited duration (favoring sequential counting, hence spatiotemporal integration). All patients showed reduced deployment of attention over space (simultanagnosia), resulting in increased visual search times and underestimations of the number of briefly presented dots. Only two patients showed ocular revisiting behavior that caused frequent omissions in visual search and overestimations of the number of dots presented for unlimited duration. The impairment to deploy attention is considered here as a bilateral covert attention deficit. Disorganized ocular exploration appears to be independent and is hypothesized to result from processes maintaining a salience map over time (spatial working memory) and especially across saccades. © 2015 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals Inc. on behalf of The New York Academy of Sciences.

  17. Combination of attentional and spatial working memory deficits in Bálint–Holmes syndrome

    Science.gov (United States)

    Pisella, Laure; Biotti, Damien; Vighetto, Alain

    2015-01-01

    This study aims to investigate whether attention and spatiotemporal integration deficits are dissociated in patients with bilateral posterior cortical atrophy (PCA), and whether it is their combination that leads to a severe clinical handicap. We recorded performance and ocular behavior of four PCA patients and four age-matched controls in visual search and counting tasks. We measured the percentage of targets detected and the mean detection time in a “pop-out” search. We also compared counting ability when a set of dots is presented briefly (in healthy individuals, the automatic deployment of attention over space allows a fast estimation of quantity) or for unlimited duration (favoring sequential counting, hence spatiotemporal integration). All patients showed reduced deployment of attention over space (simultanagnosia), resulting in increased visual search times and underestimations of the number of briefly presented dots. Only two patients showed ocular revisiting behavior that caused frequent omissions in visual search and overestimations of the number of dots presented for unlimited duration. The impairment to deploy attention is considered here as a bilateral covert attention deficit. Disorganized ocular exploration appears to be independent and is hypothesized to result from processes maintaining a salience map over time (spatial working memory) and especially across saccades. PMID:25708555

  18. Closed-loop training of attention with real-time brain imaging.

    Science.gov (United States)

    deBettencourt, Megan T; Cohen, Jonathan D; Lee, Ray F; Norman, Kenneth A; Turk-Browne, Nicholas B

    2015-03-01

    Lapses of attention can have negative consequences, including accidents and lost productivity. Here we used closed-loop neurofeedback to improve sustained attention abilities and reduce the frequency of lapses. During a sustained attention task, the focus of attention was monitored in real time with multivariate pattern analysis of whole-brain neuroimaging data. When indicators of an attentional lapse were detected in the brain, we gave human participants feedback by making the task more difficult. Behavioral performance improved after one training session, relative to control participants who received feedback from other participants' brains. This improvement was largest when feedback carried information from a frontoparietal attention network. A neural consequence of training was that the basal ganglia and ventral temporal cortex came to represent attentional states more distinctively. These findings suggest that attentional failures do not reflect an upper limit on cognitive potential and that attention can be trained with appropriate feedback about neural signals.

  19. Managerial Attention in International SMEs

    NARCIS (Netherlands)

    Fan, Jiasi

    2017-01-01

    Managerial attention affects organizational strategies and the resulting consequences. In the international business context, it is noted that how much attention managers give to the international marketplace, i.e., international attention, has profound implications for large global companies’

  20. The impact of acute psychosocial stress on magnetoencephalographic correlates of emotional attention and exogenous visual attention.

    Directory of Open Access Journals (Sweden)

    Ludger Elling

    Full Text Available Stress-induced acute activation of the cerebral catecholaminergic systems has often been found in rodents. However, little is known regarding the consequences of this activation on higher cognitive functions in humans. Theoretical inferences would suggest increased distractibility in the sense of increased exogenous attention and emotional attention. The present study investigated the influence of acute stress responses on magnetoencephalographic (MEG correlates of visual attention. Healthy male subjects were presented emotional and neutral pictures in three subsequent MEG recording sessions after being exposed to a TSST-like social stressor, intended to trigger a HPA-response. The subjects anticipation of another follow-up stressor was designed to sustain the short-lived central catecholaminergic stress reactions throughout the ongoing MEG recordings. The heart rate indicates a stable level of anticipatory stress during this time span, subsequent cortisol concentrations and self-report measures of stress were increased. With regard to the MEG correlates of attentional functions, we found that the N1m amplitude remained constantly elevated during stressor anticipation. The magnetic early posterior negativity (EPNm was present but, surprisingly, was not at all modulated during stressor anticipation. This suggests that a general increase of the influence of exogenous attention but no specific effect regarding emotional attention in this time interval. Regarding the time course of the effects, an influence of the HPA on these MEG correlates of attention seems less likely. An influence of cerebral catecholaminergic systems is plausible, but not definite.

  1. Phenomenology of Joint Attention

    African Journals Online (AJOL)

    denise

    of phenomenology by offering a phenomenology of joint attention. The first section reviews elementary. Husserlian phenomenology and introduces a system for symbolically representing the structure of intentional mental states. The second section summarizes Edith Stein's phenomenological description of empathy, the ...

  2. The Attention Economy

    Directory of Open Access Journals (Sweden)

    Süreyya Çankırı

    2013-11-01

    Full Text Available Understanding the New Currency of Business (originally published by Harvard Business School Press stands out as a new and significant work. The book analyses the psychological dimensions of attention while presenting its key applications in advertising, e­commerce, information management and strategy.

  3. Quantum Phase Transitions in Quantum Dots

    OpenAIRE

    Rau, I. G.; Amasha, S.; Oreg, Y.; Goldhaber-Gordon, D.

    2013-01-01

    This review article describes theoretical and experimental advances in using quantum dots as a system for studying impurity quantum phase transitions and the non-Fermi liquid behavior at the quantum critical point.

  4. Double quantum dots defined in bilayer graphene

    Science.gov (United States)

    Żebrowski, D. P.; Peeters, F. M.; Szafran, B.

    2017-07-01

    Artificial molecular states of double quantum dots defined in bilayer graphene are studied with the atomistic tight-binding method and its low-energy continuum approximation. We indicate that the extended electron wave functions have opposite parities on sublattices of the layers and that the ground-state wave-function components change from bonding to antibonding with the interdot distance. In the weak-coupling limit, the one most relevant for quantum dots defined electrostatically, the signatures of the interdot coupling include, for the two-electron ground state, formation of states with symmetric or antisymmetric spatial wave functions split by the exchange energy. In the high-energy part of the spectrum the states with both electrons in the same dot are found with the splitting of energy levels corresponding to simultaneous tunneling of the electron pair from one dot to the other.

  5. Large quantum dots with small oscillator strength

    DEFF Research Database (Denmark)

    Stobbe, Søren; Schlereth, T.W.; Höfling, S.

    2010-01-01

    We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots...... is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy...

  6. Ge Quantum Dot Infrared Imaging Camera Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna Innovations Incorporated proposes to develop a high performance Ge quantum dots-based infrared (IR) imaging camera on Si substrate. The high sensitivity, large...

  7. Carbon Quantum Dots for Zebrafish Fluorescence Imaging

    National Research Council Canada - National Science Library

    Kang, Yan-Fei; Li, Yu-Hao; Fang, Yang-Wu; Xu, Yang; Wei, Xiao-Mi; Yin, Xue-Bo

    2015-01-01

    Carbon quantum dots (C-QDs) are becoming a desirable alternative to metal-based QDs and dye probes owing to their high biocompatibility, low toxicity, ease of preparation, and unique photophysical properties...

  8. Preparation and Application of Fluorescent Carbon Dots

    National Research Council Canada - National Science Library

    Zuo, Jun; Jiang, Tao; Zhao, Xiaojing; Xiong, Xiaohong; Xiao, Saijin; Zhu, Zhiqiang

    2015-01-01

      Fluorescent carbon dots (CDs) are a novel type of fluorescent nanomaterials, which not only possess the specific quantum confinement effects of nanomaterials due to the small size of nanomaterials, but also have good...

  9. Nanomaterials: Earthworms lit with quantum dots

    Science.gov (United States)

    Tilley, Richard D.; Cheong, Soshan

    2013-01-01

    Yeast, bacteria and fungi have been used to synthesize a variety of nanocrystals. Now, the metal detoxification process in the gut of an earthworm is exploited to produce biocompatible cadmium telluride quantum dots.

  10. The Contribution of Attentional Control and Working Memory to Reading Comprehension and Decoding

    Science.gov (United States)

    Arrington, C. Nikki; Kulesz, Paulina A.; Francis, David J.; Fletcher, Jack M.; Barnes, Marcia A.

    2014-01-01

    Little is known about how specific components of working memory, namely, attentional processes including response inhibition, sustained attention, and cognitive inhibition, are related to reading decoding and comprehension. The current study evaluated the relations of reading comprehension, decoding, working memory, and attentional control in…

  11. Attention Training for School-Aged Children with ADHD: Results of an Open Trial

    Science.gov (United States)

    Tamm, Leanne; Hughes, Carroll; Ames, Laure; Pickering, Joyce; Silver, Cheryl H.; Stavinoha, Peter; Castillo, Christine L.; Rintelmann, Jeanne; Moore, Jarrette; Foxwell, Aleksandra; Bolanos, S. Gina; Hines, Tabatha; Nakonezny, Paul A.; Emslie, Graham

    2010-01-01

    Objective: The article discusses a feasibility study conducted to examine whether Pay Attention!, an intervention training sustained, selective, alternating, and divided attention, could be utilized in a clinical setting with children diagnosed with ADHD, and whether children who received the intervention made attention and executive functioning…

  12. Psychological Factors, Beliefs About Medication, and Adherence of Youth with HIV-1 in a Multisite Directly Observed Therapy (DOT) Pilot Study

    Science.gov (United States)

    Garvie, Patricia A.; Flynn, Patricia M.; Belzer, Marvin; Britto, Paula; Hu, Chengcheng; Graham, Bobbie; Neely, Michael; McSherry, George D.; Spector, Stephen A.; Gaur, Aditya H.

    2010-01-01

    Introduction Examine psychological functioning and beliefs about medicine in adolescents with HIV-1 on HAART in a community-based directly observed therapy (DOT) pilot feasibility study. Methods Youth with behaviorally-acquired HIV (n=20; 65% female; median age 21 years) with adherence problems, received once-daily DOT. Youth were assessed at baseline, week 12 (post-DOT) and week 24 (follow-up). Results Baseline to week 12 comparisons: 55% of youth reported clinical depressive symptoms compared to 27% at week 12 with sustained improvements at week 24. Substance use: Borderline clinical range (Tscore=68), with clinical but statistically non-significant improvement (Tscore=61). Hopelessness scores reflected optimism for the future. Coping strategies showed significantly decreased Cognitive Avoidance (p=0.02), Emotional Discharge (p=0.004), and Acceptance/Resignation (“nothing I can do,” p=0.004); Positive Reappraisal and Seeking Support emerged. Aside from depressive symptoms, week 12 improvements were not sustained at week 24. DOT adherence was predicted by higher baseline depression (p=0.05), Beliefs About Medicine (p=0.006) and Perceived Threat of illness scores (p=0.03). Discussion Youth with behaviorally-acquired HIV and adherence problems who participated in a community-based DOT intervention reported clinically improved depressive symptoms, and temporarily reduced substance use and negative coping strategies. Depressive symptoms, Beliefs About Medicine and viewing HIV as a threat predicted better DOT adherence. PMID:21575827

  13. Micromagnetic Simulations of Submicron Cobalt Dots

    Energy Technology Data Exchange (ETDEWEB)

    Parker, G.J.; Cerjan, C.

    1999-08-30

    Numerical simulations of submicron Co extruded elliptical dots were performed to illustrate the relative importance of different physical parameters on the switching behavior in the easy direction. Shape, size, magnetic moment magnitude and crystalline anisotropy, both magnitude and distribution, were varied. The simulation includes calculation of the magnetostatic, exchange and crystalline anisotropy fields on a structured mesh using finite difference techniques. The smooth boundary of the dots are accurately represented by use of the Embedded Curve Boundary method.

  14. SUSTAINABLE CHEMISTRY FOR SUSTAINABLE INDUSTRY

    Directory of Open Access Journals (Sweden)

    G. Rizzuto

    2015-01-01

    Full Text Available Foundry Alfe Chem is an industrial reality working in the field of lubrication and chemical auxiliaries for industrial processes, which falls within the framework of the emerging and increasingly important «green chemistry». The goal of the company is to develop products that are more environmentally friendly by using raw materials from renewable sources; specifically, Foundry Alfe Chem has a program of self-sustainability that contemplates, for the foreseeable future, the direct production of renewable raw materials. The company has developed a new dedicated product line, Olitema, whose purpose is to offer highly technological solutions with complete environmental sustainability. In this context, Foundry Alfe CHEM has created a new product which represents a breakthrough in the class of HFC hydraulic fluids: Ecosafe Plus is a biodegradable fire-resistant hydraulic fluid with high engineering and technological performances, high environmental sustainability and the best security guarantees in workplaces. Its formulation is glycols-free, and it allows for easier disposal of the exhausted fluid, compared to a traditional water/ glycol-based HFC hydraulic fluid. For what concern the technological properties, Ecosafe Plus has been tested by accredited laboratories with tribological trials (4 Ball wear test ASTM D 4172, Ball on disc test ASTM 6425, Brugger test DIN 51347, Vickers test ASTM D 2882, with elastomer compatibility test (ASTM D 471 and biodegradability test (OECD 310 F.

  15. Attention training through gaze-contingent feedback: Effects on reappraisal and negative emotions.

    Science.gov (United States)

    Sanchez, Alvaro; Everaert, Jonas; Koster, Ernst H W

    2016-10-01

    Reappraisal is central to emotion regulation but its mechanisms are unclear. This study tested the theoretical prediction that emotional attention bias is linked to reappraisal of negative emotion-eliciting stimuli and subsequent emotional responding using a novel attentional control training. Thirty-six undergraduates were randomly assigned to either the control or the attention training condition and were provided with different task instructions while they performed an interpretation task. Whereas control participants freely created interpretations, participants in the training condition were instructed to allocate attention toward positive words to efficiently create positive interpretations (i.e., recruiting attentional control) while they were provided with gaze-contingent feedback on their viewing behavior. Transfer to attention bias and reappraisal success was evaluated using a dot-probe task and an emotion regulation task which were administered before and after the training. The training condition was effective at increasing attentional control and resulted in beneficial effects on the transfer tasks. Analyses supported a serial indirect effect with larger attentional control acquisition in the training condition leading to negative attention bias reduction, in turn predicting greater reappraisal success which reduced negative emotions. Our results indicate that attentional mechanisms influence the use of reappraisal strategies and its impact on negative emotions. The novel attention training highlights the importance of tailored feedback to train attentional control. The findings provide an important step toward personalized delivery of attention training. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  16. Bonobos (Pan paniscus) show an attentional bias toward conspecifics’ emotions

    Science.gov (United States)

    Kret, Mariska E.; Jaasma, Linda; Bionda, Thomas; Wijnen, Jasper G.

    2016-01-01

    In social animals, the fast detection of group members’ emotional expressions promotes swift and adequate responses, which is crucial for the maintenance of social bonds and ultimately for group survival. The dot-probe task is a well-established paradigm in psychology, measuring emotional attention through reaction times. Humans tend to be biased toward emotional images, especially when the emotion is of a threatening nature. Bonobos have rich, social emotional lives and are known for their soft and friendly character. In the present study, we investigated (i) whether bonobos, similar to humans, have an attentional bias toward emotional scenes compared with conspecifics showing a neutral expression, and (ii) which emotional behaviors attract their attention the most. As predicted, results consistently showed that bonobos’ attention was biased toward the location of the emotional versus neutral scene. Interestingly, their attention was grabbed most by images showing conspecifics such as sexual behavior, yawning, or grooming, and not as much—as is often observed in humans—by signs of distress or aggression. The results suggest that protective and affiliative behaviors are pivotal in bonobo society and therefore attract immediate attention in this species. PMID:26976586

  17. Bonobos (Pan paniscus) show an attentional bias toward conspecifics' emotions.

    Science.gov (United States)

    Kret, Mariska E; Jaasma, Linda; Bionda, Thomas; Wijnen, Jasper G

    2016-04-05

    In social animals, the fast detection of group members' emotional expressions promotes swift and adequate responses, which is crucial for the maintenance of social bonds and ultimately for group survival. The dot-probe task is a well-established paradigm in psychology, measuring emotional attention through reaction times. Humans tend to be biased toward emotional images, especially when the emotion is of a threatening nature. Bonobos have rich, social emotional lives and are known for their soft and friendly character. In the present study, we investigated (i) whether bonobos, similar to humans, have an attentional bias toward emotional scenes compared with conspecifics showing a neutral expression, and (ii) which emotional behaviors attract their attention the most. As predicted, results consistently showed that bonobos' attention was biased toward the location of the emotional versus neutral scene. Interestingly, their attention was grabbed most by images showing conspecifics such as sexual behavior, yawning, or grooming, and not as much-as is often observed in humans-by signs of distress or aggression. The results suggest that protective and affiliative behaviors are pivotal in bonobo society and therefore attract immediate attention in this species.

  18. Quantum Dot-Based Nanoprobes for In Vivo Targeted Imaging

    Science.gov (United States)

    Zhu, Yian; Hong, Hao; Xu, Zhi Ping; Li, Zhen; Cai, Weibo

    2013-01-01

    Fluorescent semiconductor quantum dots (QDs) have attracted tremendous attention over the last decade. The superior optical properties of QDs over conventional organic dyes make them attractive labels for a wide variety of biomedical applications, whereas their potential toxicity and instability in biological environment has puzzled scientific researchers. Much research effort has been devoted to surface modification and functionalization of QDs to make them versatile probes for biomedical applications, and significant progress has been made over the last several years. This review article aims to describe the current state-of-the-art of the synthesis, modification, bioconjugation, and applications of QDs for in vivo targeted imaging. In addition, QD-based multifunctional nanoprobes are also summarized. PMID:24206136

  19. Quantum-dot-in-perovskite solids

    KAUST Repository

    Ning, Zhijun

    2015-07-15

    © 2015 Macmillan Publishers Limited. All rights reserved. Heteroepitaxy - atomically aligned growth of a crystalline film atop a different crystalline substrate - is the basis of electrically driven lasers, multijunction solar cells, and blue-light-emitting diodes. Crystalline coherence is preserved even when atomic identity is modulated, a fact that is the critical enabler of quantum wells, wires, and dots. The interfacial quality achieved as a result of heteroepitaxial growth allows new combinations of materials with complementary properties, which enables the design and realization of functionalities that are not available in the single-phase constituents. Here we show that organohalide perovskites and preformed colloidal quantum dots, combined in the solution phase, produce epitaxially aligned \\'dots-in-a-matrix\\' crystals. Using transmission electron microscopy and electron diffraction, we reveal heterocrystals as large as about 60 nanometres and containing at least 20 mutually aligned dots that inherit the crystalline orientation of the perovskite matrix. The heterocrystals exhibit remarkable optoelectronic properties that are traceable to their atom-scale crystalline coherence: photoelectrons and holes generated in the larger-bandgap perovskites are transferred with 80% efficiency to become excitons in the quantum dot nanocrystals, which exploit the excellent photocarrier diffusion of perovskites to produce bright-light emission from infrared-bandgap quantum-tuned materials. By combining the electrical transport properties of the perovskite matrix with the high radiative efficiency of the quantum dots, we engineer a new platform to advance solution-processed infrared optoelectronics.

  20. Quantum dots and spin qubits in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Recher, Patrik; Trauzettel, Bjoern, E-mail: precher@physik.uni-wuerzburg.de, E-mail: trauzettel@physik.uni-wuerzburg.de [Institut fuer Theoretische Physik und Astrophysik, University of Wuerzburg, 97074 Wuerzburg (Germany)

    2010-07-30

    This is a review on graphene quantum dots and their use as a host for spin qubits. We discuss the advantages but also the challenges to use graphene quantum dots for spin qubits as compared to the more standard materials like GaAs. We start with an overview of this young and fascinating field and then discuss gate-tunable quantum dots in detail. We calculate the bound states for three different quantum dot architectures where a bulk gap allows for confinement via electrostatic fields: (i) graphene nanoribbons with armchair boundaries, (ii) a disc in single-layer graphene, and (iii) a disc in bilayer graphene. In order for graphene quantum dots to be useful in the context of spin qubits, one needs to find reliable ways to break the valley degeneracy. This is achieved here, either by a specific termination of graphene in (i) or in (ii) and (iii) by a magnetic field, without the need of a specific boundary. We further discuss how to manipulate spin in these quantum dots and explain the mechanism of spin decoherence and relaxation caused by spin-orbit interaction in combination with electron-phonon coupling, and by hyperfine interaction with the nuclear-spin system. (topical review)