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Sample records for controlled pupil size

  1. Luminance controlled pupil size affects Landolt C task performance. Revision

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    Berman, S.M. [Lawrence Berkeley Lab., CA (United States); Fein, G. [Neurobehavioral Lab. Software, San Rafael, CA (United States); Jewett, D.L.; Ashford, F. [ABRATech Corp., Mill Valley, CA (United States)

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m{sup 2} and 73 cd/m{sup 2}. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  2. Luminance controlled pupil size affects Landolt C task performance

    Energy Technology Data Exchange (ETDEWEB)

    Berman, S.M. (Lawrence Berkeley Lab., CA (United States)); Fein, G. (Neurobehavioral Lab. Software, San Rafael, CA (United States)); Jewett, D.L.; Ashford, F. (ABRATech Corp., Mill Valley, CA (United States))

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m[sup 2] and 73 cd/m[sup 2]. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  3. Pupil size tracks perceptual content and surprise.

    Science.gov (United States)

    Kloosterman, Niels A; Meindertsma, Thomas; van Loon, Anouk M; Lamme, Victor A F; Bonneh, Yoram S; Donner, Tobias H

    2015-04-01

    Changes in pupil size at constant light levels reflect the activity of neuromodulatory brainstem centers that control global brain state. These endogenously driven pupil dynamics can be synchronized with cognitive acts. For example, the pupil dilates during the spontaneous switches of perception of a constant sensory input in bistable perceptual illusions. It is unknown whether this pupil dilation only indicates the occurrence of perceptual switches, or also their content. Here, we measured pupil diameter in human subjects reporting the subjective disappearance and re-appearance of a physically constant visual target surrounded by a moving pattern ('motion-induced blindness' illusion). We show that the pupil dilates during the perceptual switches in the illusion and a stimulus-evoked 'replay' of that illusion. Critically, the switch-related pupil dilation encodes perceptual content, with larger amplitude for disappearance than re-appearance. This difference in pupil response amplitude enables prediction of the type of report (disappearance vs. re-appearance) on individual switches (receiver-operating characteristic: 61%). The amplitude difference is independent of the relative durations of target-visible and target-invisible intervals and subjects' overt behavioral report of the perceptual switches. Further, we show that pupil dilation during the replay also scales with the level of surprise about the timing of switches, but there is no evidence for an interaction between the effects of surprise and perceptual content on the pupil response. Taken together, our results suggest that pupil-linked brain systems track both the content of, and surprise about, perceptual events.

  4. A circuit for pupil orienting responses: implications for cognitive modulation of pupil size.

    Science.gov (United States)

    Wang, Chin-An; Munoz, Douglas P

    2015-08-01

    Pupil size, as a component of orienting, changes rapidly in response to local salient events in the environment, in addition to its well-known illumination-dependent modulation. Recent research has shown that visual, auditory, or audiovisual stimuli can elicit transient pupil dilation, and the timing and size of the evoked responses are systematically modulated by stimulus salience. Moreover, weak microstimulation of the superior colliculus (SC), a midbrain structure involved in eye movements and attention, evokes similar transient pupil dilation, suggesting that the SC coordinates the orienting response which includes transient pupil dilation. Projections from the SC to the pupil control circuitry provide a novel neural substrate underlying pupil modulation by various cognitive processes.

  5. Personality and Pupil Control Behavior.

    Science.gov (United States)

    Helsel, A. Ray

    Pupil control behavior is conceptualized as a continuum ranging from custodialism, which views students as irresponsible and undisciplined and needing strictness and punishment, to humanism, which emphasizes a democratic atmosphere in which students are capable of self-discipline and are treated accordingly. The theoretical framework for this…

  6. Personality and Pupil Control Behavior.

    Science.gov (United States)

    Helsel, A. Ray

    Pupil control behavior is conceptualized as a continuum ranging from custodialism, which views students as irresponsible and undisciplined and needing strictness and punishment, to humanism, which emphasizes a democratic atmosphere in which students are capable of self-discipline and are treated accordingly. The theoretical framework for this…

  7. Effect of Pupil Size on Wavefront Refraction during Orthokeratology.

    Science.gov (United States)

    Faria-Ribeiro, Miguel; Navarro, Rafael; González-Méijome, José Manuel

    2016-11-01

    It has been hypothesized that central and peripheral refraction, in eyes treated with myopic overnight orthokeratology, might vary with changes in pupil diameter. The aim of this work was to evaluate the axial and peripheral refraction and optical quality after orthokeratology, using ray tracing software for different pupil sizes. Zemax-EE was used to generate a series of 29 semi-customized model eyes based on the corneal topography changes from 29 patients who had undergone myopic orthokeratology. Wavefront refraction in the central 80 degrees of the visual field was calculated using three different quality metrics criteria: Paraxial curvature matching, minimum root mean square error (minRMS), and the Through Focus Visual Strehl of the Modulation Transfer Function (VSMTF), for 3- and 6-mm pupil diameters. The three metrics predicted significantly different values for foveal and peripheral refractions. Compared with the Paraxial criteria, the other two metrics predicted more myopic refractions on- and off-axis. Interestingly, the VSMTF predicts only a marginal myopic shift in the axial refraction as the pupil changes from 3 to 6 mm. For peripheral refraction, minRMS and VSMTF metric criteria predicted a higher exposure to peripheral defocus as the pupil increases from 3 to 6 mm. The results suggest that the supposed effect of myopic control produced by ortho-k treatments might be dependent on pupil size. Although the foveal refractive error does not seem to change appreciably with the increase in pupil diameter (VSMTF criteria), the high levels of positive spherical aberration will lead to a degradation of lower spatial frequencies, that is more significant under low illumination levels.

  8. Relationships among Teacher Personality, Pupil Control Attidues, and Pupil Control Behavior.

    Science.gov (United States)

    Bush, Doris W.

    This research examined the relationships among three variables--teacher personality, teacher pupil control attitudes, and teacher pupil control behavior--to determine whether teacher personality or pupil control attitudes were the better predictor of pupil control behavior. Subjects were 102 junior high school teachers. The major finding of the…

  9. Pupil size behavior during online processing of sentences.

    Science.gov (United States)

    Fernández, G; Biondi, J; Castro, S; Agamenonni, O

    2016-12-01

    In the present work we analyzed the pupil size behavior of 40 subjects while they read well-defined sentences with different contextual predictability (i.e., regular sentences and proverbs). In general, pupil size increased when reading regular sentences, but when readers realized that they were reading proverbs their pupils strongly increase until finishing proverbs' reading. Our results suggest that an increased pupil size is not limited to cognitive load (i.e., relative difficulty in processing) because when participants accurately recognized words during reading proverbs, theirs pupil size increased too. Our results show that pupil size dynamics may be a reliable measure to investigate the cognitive processes involved in sentence processing and memory functioning.

  10. Can pupil size and pupil responses during visual scanning contribute to the diagnosis of autism spectrum disorder in children?

    Science.gov (United States)

    Martineau, Joëlle; Hernandez, Nadia; Hiebel, Lorraine; Roché, Laetitia; Metzger, Aude; Bonnet-Brilhault, Frédérique

    2011-08-01

    The purpose of this study was to determine whether baseline pupil size and pupil responses during visual scanning with eye-tracking technology could discriminate children with autism spectrum disorder (ASD) from mental age-matched and chronological age-matched controls. To this end, we used stimuli consisting in still color photographs presented centrally to the participant's midline on a stimulus monitor. Each child was presented with a series of neutral faces, virtual faces (avatars) and different objects, separated by black slides. We recorded the mean pupil size and pupil size changes over time in each of the three categories of stimuli and during exposure to the black slides. Fifty-seven children participated in study (19 ASD, mean age 118 months; 19 mental age-matched controls, mean age 87 months; and 19 chronological age-matched controls, mean age 118 months). We compared the baseline pupil size and pupil responses during visual scanning among the three diagnostic groups. During the presentation of slides, the mean pupil size in the ASD group was clearly smaller than in the MA-matched and CA-matched groups. Discriminate analysis of pupil size during the presentation of black slides and slides with visual stimuli successfully predicted group membership in 72% of the participants. Group membership was correctly classified in 89% of the participants in the ASD group, in 63% in the MA-matched group and in 63% in the CA-matched group. These potential biomarkers may contribute to our understanding of the differences in neurological development in the brain in autism and could prove useful as indicators of ASD.

  11. Disruption of pupil size modulation correlates with voluntary motor preparation deficits in Parkinson's disease.

    Science.gov (United States)

    Wang, Chin-An; McInnis, Hailey; Brien, Donald C; Pari, Giovanna; Munoz, Douglas P

    2016-01-08

    Pupil size is an easy-to-measure, non-invasive method to index various cognitive processes. Although a growing number of studies have incorporated measures of pupil size into clinical investigation, there have only been limited studies in Parkinson's disease (PD). Convergent evidence has suggested PD patients exhibit cognitive impairment at or soon after diagnosis. Here, we used an interleaved pro- and anti-saccade paradigm while monitoring pupil size with saccadic eye movements to examine the relationship between executive function deficits and pupil size in PD patients. Subjects initially fixated a central cue, the color of which instructed them to either look at a peripheral stimulus automatically (pro-saccade) or suppress the automatic response and voluntarily look in the opposite direction of the stimulus (anti-saccade). We hypothesized that deficits of voluntary control should be revealed not only on saccadic but also on pupil responses because of the recently suggested link between the saccade and pupil control circuits. In elderly controls, pupil size was modulated by task preparation, showing larger dilation prior to stimulus appearance in preparation for correct anti-saccades, compared to correct pro-saccades, or erroneous pro-saccades made in the anti-saccade condition. Moreover, the size of pupil dilation correlated negatively with anti-saccade reaction times. However, this profile of pupil size modulation was significantly blunted in PD patients, reflecting dysfunctional circuits for anti-saccade preparation. Our results demonstrate disruptions of modulated pupil responses by voluntary movement preparation in PD patients, highlighting the potential of using low-cost pupil size measurement to examine executive function deficits in early PD.

  12. Computerized mouse pupil size measurement for pupillary light reflex analysis.

    Science.gov (United States)

    Lu, Wei; Tan, Jinglu; Zhang, Keqing; Lei, Bo

    2008-06-01

    Accurate measurement of pupil size is essential for pupillary light reflex (PLR) analysis in clinical diagnosis and vision research. Low pupil-iris contrast, corneal reflection, artifacts and noises in infrared eye imaging pose challenges for automated pupil detection and measurement. This paper describes a computerized method for pupil detection or identification. After segmentation by a region-growing algorithm, pupils are detected by an iterative randomized Hough transform (IRHT) with an elliptical model. The IRHT iteratively suppresses the effects of extraneous structures and noise, yielding reliable measurements. Experimental results with 72 images showed a mean absolute difference of 3.84% between computerized and manual measurements. The inter-run variation for the computerized method (1.24%) was much smaller than the inter-observer variation for the manual method (7.45%), suggesting a higher level of consistency of the former. The computerized method could facilitate PLR analysis and other non-invasive functional tests that require pupil size measurements.

  13. Principals' Pupil Control Behavior and School Robustness.

    Science.gov (United States)

    Smedley, Stanley R.; Willower, Donald J.

    1981-01-01

    A survey of 3,100 students, teachers, and principals in 47 elementary and secondary schools in the Middle Atlantic region, using the Pupil Control Behavior Form, revealed a positive association between principals' humanistic pupil control behavior and schools'"robustness" (the degree of meaning and excitement students find in school).…

  14. Organizational Pressure, Personal Ideology and Teacher Pupil Control Behaviour.

    Science.gov (United States)

    Blust, Ross S.; Willower, Donald J.

    1979-01-01

    It was found that teachers' own views on pupil control predicted their pupil control behavior, while organizational pressures, represented by teacher perceptions of the pupil control views of colleagues and the principal, failed to do so. (Author/IRT)

  15. Toward Definition and Measurement of Pupil Control Behaviour

    Science.gov (United States)

    Helsel, A. Ray; Willower, Donald J.

    1974-01-01

    Pupil control is regarded as an integrative theme to explain the collection of extensive observations made in schools. This report attempts to define and measure pupil control behavior, a companion concept to pupil control ideology. (Author/WM)

  16. Pupil Control Ideology in Predicting Teacher Discipline Referrals.

    Science.gov (United States)

    Foley, Walter J.; Brooks, Robert

    1978-01-01

    Concludes that humanism in teachers is related to reporting fewer unresolvable conflicts with pupils and that pupil control ideology and subsequent teacher control behavior (the referring of pupils to the administration for disciplinary action) are related. (Author/IRT)

  17. Chimpanzees and humans mimic pupil-size of conspecifics.

    Science.gov (United States)

    Kret, Mariska E; Tomonaga, Masaki; Matsuzawa, Tetsuro

    2014-01-01

    Group-living typically provides benefits to individual group members but also confers costs. To avoid incredulity and betrayal and allow trust and cooperation, individuals must understand the intentions and emotions of their group members. Humans attend to other's eyes and from gaze and pupil-size cues, infer information about the state of mind of the observed. In humans, pupil-size tends to mimic that of the observed. Here we tested whether pupil-mimicry exists in our closest relative, the chimpanzee (P. troglodytes). We conjectured that if pupil-mimicry has adaptive value, e.g. to promote swift communication of inner states and facilitate shared understanding and coordination, pupil-mimicry should emerge within but not across species. Pupillometry data was collected from human and chimpanzee subjects while they observed images of the eyes of both species with dilating/constricting pupils. Both species showed enhanced pupil-mimicry with members of their own species, with effects being strongest in humans and chimpanzee mothers. Pupil-mimicry may be deeply-rooted, but probably gained importance from the point in human evolution where the morphology of our eyes became more prominent. Humans' white sclera surrounding the iris, and the fine muscles around their eyes facilitate non-verbal communication via eye signals.

  18. Chimpanzees and humans mimic pupil-size of conspecifics.

    Directory of Open Access Journals (Sweden)

    Mariska E Kret

    Full Text Available Group-living typically provides benefits to individual group members but also confers costs. To avoid incredulity and betrayal and allow trust and cooperation, individuals must understand the intentions and emotions of their group members. Humans attend to other's eyes and from gaze and pupil-size cues, infer information about the state of mind of the observed. In humans, pupil-size tends to mimic that of the observed. Here we tested whether pupil-mimicry exists in our closest relative, the chimpanzee (P. troglodytes. We conjectured that if pupil-mimicry has adaptive value, e.g. to promote swift communication of inner states and facilitate shared understanding and coordination, pupil-mimicry should emerge within but not across species. Pupillometry data was collected from human and chimpanzee subjects while they observed images of the eyes of both species with dilating/constricting pupils. Both species showed enhanced pupil-mimicry with members of their own species, with effects being strongest in humans and chimpanzee mothers. Pupil-mimicry may be deeply-rooted, but probably gained importance from the point in human evolution where the morphology of our eyes became more prominent. Humans' white sclera surrounding the iris, and the fine muscles around their eyes facilitate non-verbal communication via eye signals.

  19. Pupil size influences the eye-tracker signal during saccades.

    Science.gov (United States)

    Nyström, Marcus; Hooge, Ignace; Andersson, Richard

    2016-04-01

    While it is known that scleral search coils-measuring the rotation of the eye globe--and modern, video based eye trackers-tracking the center of the pupil and the corneal reflection (CR)--produce signals with different properties, the mechanisms behind the differences are less investigated. We measure how the size of the pupil affects the eye-tracker signal recorded during saccades with a common pupil-CR eye-tracker. Eye movements were collected from four healthy participants and one person with an aphakic eye while performing self-paced, horizontal saccades at different levels of screen luminance and hence pupil size. Results show that pupil-, and gaze-signals, but not the CR-signal, are affected by the size of the pupil; changes in saccade peak velocities in the gaze signal of more than 30% were found. It is important to be aware of this pupil size dependent change when comparing fine grained oculomotor behavior across participants and conditions.

  20. Pupil size reflects the focus of feature-based attention.

    Science.gov (United States)

    Binda, Paola; Pereverzeva, Maria; Murray, Scott O

    2014-12-15

    We measured pupil size in adult human subjects while they selectively attended to one of two surfaces, bright and dark, defined by coherently moving dots. The two surfaces were presented at the same location; therefore, subjects could select the cued surface only on the basis of its features. With no luminance change in the stimulus, we find that pupil size was smaller when the bright surface was attended and larger when the dark surface was attended: an effect of feature-based (or surface-based) attention. With the same surfaces at nonoverlapping locations, we find a similar effect of spatial attention. The pupil size modulation cannot be accounted for by differences in eye position and by other variables known to affect pupil size such as task difficulty, accommodation, or the mere anticipation (imagery) of bright/dark stimuli. We conclude that pupil size reflects not just luminance or cognitive state, but the interaction between the two: it reflects which luminance level in the visual scene is relevant for the task at hand.

  1. Eye movement and pupil size constriction under discomfort glare.

    Science.gov (United States)

    Lin, Yandan; Fotios, Steve; Wei, Minchen; Liu, Yihong; Guo, Weihong; Sun, Yaojie

    2015-01-29

    Involuntary physiological responses offer an alternative means to psychophysical procedures for objectively evaluating discomfort glare. This study examined eye movement and pupil size responses to glare discomfort using new approaches to analysis: relative pupil size and speed of eye movement. Participants evaluated glare discomfort using the standard de Boer rating scale under various conditions manipulated to influence glare discomfort. Eye movement was recorded using an electro-oculogram (EOG), and pupil size was recorded using Tobii glasses. Ten young (mean age: 24.5 years old) and 10 senior (mean age: 61 years old) participants were recruited for this experiment. Subjective evaluation of glare discomfort was highly correlated with eye movement (multiple correlation coefficient [R(2)] of >0.94, P < 0.001) and pupil constriction (R(2) = 0.38, P < 0.001). Severe glare discomfort increased the speed of eye movement and caused larger pupil constriction. Larger variations of eye movement were found among seniors. The two physiological responses studied here to characterize discomfort glare under various lighting conditions had significant correlation with the subjective evaluation. The correlation between discomfort glare and physiological responses suggests an objective way to characterize and evaluate discomfort glare that may overcome the problems of conventional subjective evaluation. It also offers an explanation as to why long-term exposure to discomfort glare leads to visual fatigue and eyestrain. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

  2. Permanent alterations in muscarinic receptors and pupil size produced by chronic atropinization in kittens

    Energy Technology Data Exchange (ETDEWEB)

    Smith, E.L.; Redburn, D.A.; Harwerth, R.S.; Maguire, G.W.

    1984-02-01

    Chronic mydriasis was induced in six kittens (four monocular, two binocular) and two adult cats (both monocular) by the daily topical application of atropine. Both the kittens and the adult cats were atropinized for a 13-week period with the treatment regimen beginning at the time of eye opening for the kittens. Pupil size measurements, obtained 1 year after the atropinization were discontinued, revealed that, although the pupils of the adult cats were normal, the pupils of the kittens' treated eyes were consistently smaller than pupils in control eyes. The status of the muscarinic receptors in the kittens' irides was investigated using /sup 3/H-QNB binding assays. In comparison with iris muscle homogenates from the control eyes, those from the treated eyes demonstrated an eightfold increase in the number of receptor binding sites. The results indicate that pupil size can be altered permanently by chronic mydriasis initiated early in the life of a kitten and that the permanent change in pupil size may result, in part, from a type of permanent supersensitivity response in the muscle following chronic blockade of muscarinic transmission by atropine.

  3. Chimpanzees and humans mimic pupil-size of conspecifics

    NARCIS (Netherlands)

    Kret, M.E.; Tomonaga, M.; Matsuzawa, T.

    2014-01-01

    Group-living typically provides benefits to individual group members but also confers costs. To avoid incredulity and betrayal and allow trust and cooperation, individuals must understand the intentions and emotions of their group members. Humans attend to other's eyes and from gaze and pupil-size c

  4. Some Comments on Inquiries on Schools and Pupil Control.

    Science.gov (United States)

    Willower, Donald J.

    This speech, by the co-author of a bibliography of studies of pupil control, reviews literature on that subject, differentiating between studies on Pupil Control Ideology (PCI) and Pupil Control Behavior (PCB), describing instances of their interrelationship, and weighing the various merits of PCI and PCB instruments. The author concludes that…

  5. Teacher Pupil Control Ideology--Behavior Congruence and Job Satisfaction.

    Science.gov (United States)

    Willower, Donald J.; Heckert, J. Wayne

    The hypothesis that teacher pupil control ideology-behavior congruence would be positively related to teacher job satisfaction was tested. The rationale for the hypothesis was that teachers whose beliefs and behaviors concerning pupil control were consistent would be likely to be contented with their work. Pupil control was seen as a central…

  6. Toward Definition and Measurement of Pupil Control Behavior.

    Science.gov (United States)

    Helsel, A. Ray; Willower, Donald J.

    An attempt is made to define and measure pupil control "behavior." In order to measure pupil control behavior, an instrument called the Pupil Control Behavior (PCB) Form was developed and tested. The 31 custodial and 34 humanistic items were randomized, and the initial version of the PCB Form was administered in 20 schools in Illinois…

  7. Pupil size reveals preparatory processes in the generation of pro-saccades and anti-saccades.

    Science.gov (United States)

    Wang, Chin-An; Brien, Donald C; Munoz, Douglas P

    2015-04-01

    The ability to generate flexible behaviors to accommodate changing goals in response to identical sensory stimuli is a signature that is inherited in humans and higher-level animals. In the oculomotor system, this function has often been examined with the anti-saccade task, in which subjects are instructed, prior to stimulus appearance, to either automatically look at the peripheral stimulus (pro-saccade) or to suppress the automatic response and voluntarily look in the opposite direction from the stimulus (anti-saccade). Distinct neural preparatory activity between the pro-saccade and anti-saccade conditions has been well documented, particularly in the superior colliculus (SC) and the frontal eye field (FEF), and this has shown higher inhibition-related fixation activity in preparation for anti-saccades than in preparation for pro-saccades. Moreover, the level of preparatory activity related to motor preparation is negatively correlated with reaction times. We hypothesised that preparatory signals may be reflected in pupil size through a link between the SC and the pupil control circuitry. Here, we examined human pupil dynamics during saccade preparation prior to the execution of pro-saccades and anti-saccades. Pupil size was larger in preparation for correct anti-saccades than in preparation for correct pro-saccades and erroneous pro-saccades made in the anti-saccade condition. Furthermore, larger pupil dilation prior to stimulus appearance accompanied saccades with faster reaction times, with a trial-by-trial correlation between dilation size and anti-saccade reaction times. Overall, our results demonstrate that pupil size is modulated by saccade preparation, and neural activity in the SC, together with the FEF, supports these findings, providing unique insights into the neural substrate coordinating cognitive processing and pupil diameter.

  8. Orienting of attention, pupil size, and the norepinephrine system.

    Science.gov (United States)

    Gabay, Shai; Pertzov, Yoni; Henik, Avishai

    2011-01-01

    This research examined a novel suggestion regarding the involvement of the locus coeruleus-norepinephrine (LC-NE) system in orienting reflexive (exogenous) attention. A common procedure for studying exogenous orienting of attention is Posner's cuing task. Importantly, one can manipulate the required level of target processing by changing task requirements, which, in turn, can elicit a different time course of inhibition of return (IOR). An easy task (responding to target location) produces earlier onset IOR, whereas a demanding task (responding to target identity) produces later onset IOR. Aston-Jones and Cohen (Annual Review of Neuroscience, 28, 403-450, 2005) presented a theory suggesting two different modes of LC activity: tonic and phasic. Accordingly, we suggest that in the more demanding task, the LC-NE system is activated in phasic mode, and in the easier task, it is activated in tonic mode. This, in turn, influences the appearance of IOR. We examined this suggestion by measuring participants' pupil size, which has been demonstrated to correlate with the LC-NE system, while they performed cuing tasks. We found a response-locked phasic dilation of the pupil in the discrimination task, as compared with the localization task, which may reflect different firing modes of the LC-NE system during the two tasks. We also demonstrated a correlation between pupil size at the time of cue presentation and magnitude of IOR.

  9. Effect of the observed pupil size on the amygdala of the beholders

    OpenAIRE

    Amemiya, Shiori; Ohtomo, Kuni

    2011-01-01

    Among a range of cognitive functions of the amygdala, recent studies suggest its involvement in identification of the pupil size. To further address its role, we investigated the response of the amygdala to human and cat faces with varied pupil size, taking into account the effect of the gender and subjective attractiveness ratings. Twenty-seven subjects underwent functional magnetic resonance imaging while viewing faces with large and small pupils. Large pupil faces induced increased activat...

  10. Examining the Effect of Class Size on Classroom Engagement and Teacher-Pupil Interaction: Differences in Relation to Pupil Prior Attainment and Primary vs. Secondary Schools

    Science.gov (United States)

    Blatchford, Peter; Bassett, Paul; Brown, Penelope

    2011-01-01

    It is widely recognized that we need to know more about effects of class size on classroom interactions and pupil behavior. This paper extends research by comparing effects on pupil classroom engagement and teacher-pupil interaction, and examining if effects vary by pupil attainment level and between primary and secondary schools. Systematic…

  11. Examining the Effect of Class Size on Classroom Engagement and Teacher-Pupil Interaction: Differences in Relation to Pupil Prior Attainment and Primary vs. Secondary Schools

    Science.gov (United States)

    Blatchford, Peter; Bassett, Paul; Brown, Penelope

    2011-01-01

    It is widely recognized that we need to know more about effects of class size on classroom interactions and pupil behavior. This paper extends research by comparing effects on pupil classroom engagement and teacher-pupil interaction, and examining if effects vary by pupil attainment level and between primary and secondary schools. Systematic…

  12. Pupil Control Ideology, Pupil Control Behavior and the Quality of School Life.

    Science.gov (United States)

    Lunenburg, Fred C.; Schmidt, Linda J.

    1989-01-01

    This article defines two approaches to pupil control--custodial and humanistic--and reports results of an investigation of the relationship between teacher control ideology and behavior and their influence on quality of life for students. Subjects were 239 elementary and secondary teachers and their students from 5 school districts. (IAH)

  13. ERP-pupil size correlations reveal how bilingualism enhances cognitive flexibility.

    Science.gov (United States)

    Kuipers, Jan-Rouke; Thierry, Guillaume

    2013-01-01

    A bilingual upbringing has been shown to enhance executive control, but the neural mechanisms underpinning such effect are essentially unknown. Here, we investigated whether monolingual and bilingual toddlers differ in semantic processing efficiency and their allocation of attention to expected and unexpected visual stimuli. We simultaneously recorded event-related brain potentials (ERPs) and pupil size in monolingual and bilingual toddlers presented with (spoken) word-picture pairs. Although ERP effects elicited by semantic relatedness were indistinguishable between the two children groups, pictures unrelated to the preceding word evoked greater pupil dilation than related pictures in bilinguals, but not in monolinguals. Furthermore, increasing pupil dilation to unrelated pictures was associated with decreasing N400 amplitude in bilinguals, whereas the monolingual toddlers showed the opposite association. Hence, attention to unexpected stimuli seems to hamper semantic integration in monolinguals, but to facilitate semantic integration in bilinguals, suggesting that bilingual toddlers are more tolerant to variation in word-referent mappings. Given the link between pupil dilation and norepinephrine-driven cognitive efficiency, correlations between ERP amplitude and concurrent pupil dilation provide new insights into the neural bases of the bilingual cognitive advantage. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Pupil size dynamics during fixation impact the accuracy and precision of video-based gaze estimation.

    Science.gov (United States)

    Choe, Kyoung Whan; Blake, Randolph; Lee, Sang-Hun

    2016-01-01

    Video-based eye tracking relies on locating pupil center to measure gaze positions. Although widely used, the technique is known to generate spurious gaze position shifts up to several degrees in visual angle because pupil centration can change without eye movement during pupil constriction or dilation. Since pupil size can fluctuate markedly from moment to moment, reflecting arousal state and cognitive processing during human behavioral and neuroimaging experiments, the pupil size artifact is prevalent and thus weakens the quality of the video-based eye tracking measurements reliant on small fixational eye movements. Moreover, the artifact may lead to erroneous conclusions if the spurious signal is taken as an actual eye movement. Here, we measured pupil size and gaze position from 23 human observers performing a fixation task and examined the relationship between these two measures. Results disclosed that the pupils contracted as fixation was prolonged, at both small (pupil contractions were accompanied by systematic errors in gaze position estimation, in both the ellipse and the centroid methods of pupil tracking. When pupil size was regressed out, the accuracy and reliability of gaze position measurements were substantially improved, enabling differentiation of 0.1° difference in eye position. We confirmed the presence of systematic changes in pupil size, again at both small and large scales, and its tight relationship with gaze position estimates when observers were engaged in a demanding visual discrimination task.

  15. Infra-slow oscillation (ISO of the pupil size of urethane-anaesthetised rats.

    Directory of Open Access Journals (Sweden)

    Tomasz Blasiak

    Full Text Available Multiplicity of oscillatory phenomena in a range of infra-slow frequencies (<0.01 Hz has been described in mammalian brains at different levels of organisation. The significance and manifestation in physiology and/or behaviour of many brain infra-slow oscillations (ISO remain unknown. Examples of this phenomenon are two types of ISO observed in the brains of urethane-anaesthetised rats: infra-slow, rhythmic changes in the rate of action potential firing in a few nuclei of the subcortical visual system and a sleep-like cycle of activation/deactivation visible in the EEG signal. Because both of these rhythmic phenomena involve brain networks that can influence autonomic nervous system activity, we hypothesised that these two brain ISOs can be reflected by rhythmic changes of pupil size. Thus, in the present study, we used simultaneous pupillography and ECoG recording to verify the hypothesised existence of infra-slow oscillations in the pupil size of urethane-anaesthetised rats. The obtained results showed rhythmic changes in the size of the pupils and rhythmic eyeball movements in urethane-anaesthetised rats. The observed rhythms were characterised by two different dominant components in a range of infra-slow frequencies. First, the long component had a period of ≈ 29 minutes and was present in both the irises and the eyeball movements. Second, the short component had a period of ≈ 2 minutes and was observed only in the rhythmic constrictions and dilations of the pupils. Both ISOs were simultaneously present in both eyes, and they were synchronised between the left and right eye. The long ISO component was synchronised with the cyclic alternations of the brain state, as revealed by rhythmic changes in the pattern of the ECoG signal. Based on the obtained results, we propose a model of interference of ISO present in different brain systems involved in the control of pupil size.

  16. Effect of the observed pupil size on the amygdala of the beholders.

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    Amemiya, Shiori; Ohtomo, Kuni

    2012-03-01

    Among a range of cognitive functions of the amygdala, recent studies suggest its involvement in identification of the pupil size. To further address its role, we investigated the response of the amygdala to human and cat faces with varied pupil size, taking into account the effect of the gender and subjective attractiveness ratings. Twenty-seven subjects underwent functional magnetic resonance imaging while viewing faces with large and small pupils. Large pupil faces induced increased activation in the amygdala, without interactions with either subject or stimuli gender, although no equivalent activation differences were seen for cat face stimuli. The activation differences were irrespective of the perceived attractiveness, and without explicit knowledge about the manipulation of the pupil size. These data support the idea that the amygdala is responsive not only to explicit or implicit fear, abhorrence or preference, but also to other elements that might suggest heightened vigilance of biologically relevant stimuli, which does not necessarily require subjective awareness.

  17. Pupil size directly modulates the feedforward response in human primary visual cortex independently of attention.

    Science.gov (United States)

    Bombeke, Klaas; Duthoo, Wout; Mueller, Sven C; Hopf, Jens-Max; Boehler, C Nico

    2016-02-15

    Controversy revolves around the question of whether psychological factors like attention and emotion can influence the initial feedforward response in primary visual cortex (V1). Although traditionally, the electrophysiological correlate of this response in humans (the C1 component) has been found to be unaltered by psychological influences, a number of recent studies have described attentional and emotional modulations. Yet, research into psychological effects on the feedforward V1 response has neglected possible direct contributions of concomitant pupil-size modulations, which are known to also occur under various conditions of attentional load and emotional state. Here we tested the hypothesis that such pupil-size differences themselves directly affect the feedforward V1 response. We report data from two complementary experiments, in which we used procedures that modulate pupil size without differences in attentional load or emotion while simultaneously recording pupil-size and EEG data. Our results confirm that pupil size indeed directly influences the feedforward V1 response, showing an inverse relationship between pupil size and early V1 activity. While it is unclear in how far this effect represents a functionally-relevant adaptation, it identifies pupil-size differences as an important modulating factor of the feedforward response of V1 and could hence represent a confounding variable in research investigating the neural influence of psychological factors on early visual processing.

  18. Effect of pupil size on multifocal pattern visual evoked potentials.

    Science.gov (United States)

    Martins, Alessandra; Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L; Billson, Francis A

    2003-08-01

    The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal.

  19. Pupil size signals novelty and predicts later retrieval success for declarative memories of natural scenes.

    Science.gov (United States)

    Naber, Marnix; Frässle, Stefan; Rutishauser, Ueli; Einhäuser, Wolfgang

    2013-02-08

    Declarative memories of personal experiences are a key factor in defining oneself as an individual, which becomes particularly evident when this capability is impaired. Assessing the physiological mechanisms of human declarative memory is typically restricted to patients with specific lesions and requires invasive brain access or functional imaging. We investigated whether the pupil, an accessible physiological measure, can be utilized to probe memories for complex natural visual scenes. During memory encoding, scenes that were later remembered elicited a stronger pupil constriction compared to scenes that were later forgotten. Thus, pupil size predicts success or failure of memory formation. In contrast, novel scenes elicited stronger pupil constriction than familiar scenes during retrieval. When viewing previously memorized scenes, those that were forgotten (misjudged as novel) still elicited stronger pupil constrictions than those correctly judged as familiar. Furthermore, pupil constriction was influenced more strongly if images were judged with high confidence. Thus, we propose that pupil constriction can serve as a marker of novelty. Since stimulus novelty modulates the efficacy of memory formation, our pupil measurements during learning indicate that the later forgotten images were perceived as less novel than the later remembered pictures. Taken together, our data provide evidence that pupil constriction is a physiological correlate of a neural novelty signal during formation and retrieval of declarative memories for complex, natural scenes.

  20. Pupil size influences the eye-tracker signal during saccades

    NARCIS (Netherlands)

    Nyström, M.; Hooge, I.T.C.; Anderson, R.

    2016-01-01

    While it is known that scleral search coils—measuring the rotation of the eye globe—and modern, video based eye trackers—tracking the center of the pupil and the corneal reflection (CR)—produce signals with different properties, the mechanisms behind the differences are less investigated. We measure

  1. Are Small Classes Better? Understanding Relationships between Class Size, Classroom Processes and Pupils' Learning

    Science.gov (United States)

    Pedder, David

    2006-01-01

    Twelve years ago Blatchford and Mortimore's authoritative review of class size research appeared in this journal. They concluded that a major problem with class size research was the lack of detailed studies of complex classroom processes that might mediate class size effects on pupils' learning. This article reviews two UK class size reviews and…

  2. Fixation duration surpasses pupil size as a measure of memory load in free viewing.

    Science.gov (United States)

    Meghanathan, Radha Nila; van Leeuwen, Cees; Nikolaev, Andrey R

    2014-01-01

    Oculomotor behavior reveals, not only the acquisition of visual information at fixation, but also the accumulation of information in memory across subsequent fixations. Two candidate measures were considered as indicators of such dynamic visual memory load: fixation duration and pupil size. While recording these measures, we displayed an arrangement of 3, 4 or 5 targets among distractors. Both occurred in various orientations. Participants searched for targets and reported whether in a subsequent display one of them had changed orientation. We determined to what extent fixation duration and pupil size indicate dynamic memory load, as a function of the number of targets fixated during the search. We found that fixation duration reflects the number of targets, both when this number is within and above the limit of working memory capacity. Pupil size reflects the number of targets only when it exceeds the capacity limit. Moreover, the duration of fixations on successive targets but not on distractors increases whereas pupil size does not. The increase in fixation duration with number of targets both within and above working memory capacity suggests that in free viewing fixation duration is sensitive to actual memory load as well as to processing load, whereas pupil size is indicative of processing load only. Two alternative models relating visual attention and working memory are considered relevant to these results. We discuss the results as supportive of a model which involves a temporary buffer in the interaction of attention and working memory.

  3. Corneal aberrations in keratoconic eyes: influence of pupil size and centering

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    Comastri, S A; Perez, G D; Martin, G; Bianchetti, A [Grupo de Optica y Vision, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, P. Colon 850 (C1063ACV) Buenos Aires (Argentina); Perez, L I, E-mail: comastri@fi.uba.ar [Consejo Nacional de Investigaciones CientIficas y Tecnicas, (C1033AAJ) Buenos Aires (Argentina)

    2011-01-01

    Ocular aberrations vary among subjects and under different conditions and are commonly analyzed expanding the wavefront aberration function in Zernike polynomials. In previous articles, explicit analytical formulas to transform Zernike coefficients of up to 7th order corresponding to an original pupil into those related to a contracted displaced new pupil are obtained. In the present paper these formulas are applied to 20 keratoconic corneas of varying severity. Employing the SN CT1000 topographer, aberrations of the anterior corneal surface for a pupil of semi-diameter 3 mm centered on the keratometric axis are evaluated, the relation between the higher-order root mean square wavefront error and the index KISA% characterizing keratoconus is studied and the size and centering of the ocular photopic natural pupil are determined. Using these data and the transformation formulas, new coefficients associated to the photopic pupil size are computed and their variation when coordinates origin is shifted from the keratometric axis to the ocular pupil centre is analyzed.

  4. Pupil Control Behavior, Classroom Robustness, and Self-Control: Public and Military High Schools Compared.

    Science.gov (United States)

    Sartori, Mary Ann; Bauske, Terri; Lunenburg, Fred C.

    This study investigates students' perceptions of teachers' pupil control behavior, classroom robustness, and student self-control. Results reveal an association between humanistic pupil control behavior of teachers and high levels of classroom robustness, high levels of classroom robustness and high student self-control, and teacher humanism in…

  5. Smaller pupil size and better proofreading performance with positive than with negative polarity displays.

    Science.gov (United States)

    Piepenbrock, Cosima; Mayr, Susanne; Buchner, Axel

    2014-01-01

    The 'positive polarity advantage' describes the fact that reading performance is better for dark text on light background (positive polarity) than for light text on dark background (negative polarity). We investigated the underlying mechanism by assessing pupil size and proofreading performance when reading positive and negative polarity texts. In particular, we tested the display luminance hypothesis which postulates that the typically greater brightness of positive compared to negative polarity displays leads to smaller pupil sizes and, hence, a sharper retinal image and better perception of detail. Indeed, pupil sizes were smaller and proofreading performance was better with positive than with negative polarity displays. The results are compatible with the hypothesis that the positive polarity advantage is an effect of display luminance. Limitations of the study are being discussed.

  6. School Socioeconomic Status and Teacher Pupil Control Behavior

    Science.gov (United States)

    Brown, Lorraine Hayes; And Others

    1974-01-01

    Despite contrary evidence in the literature, this experimental investigation found that race and the interaction of race and socioeconomic status of students do not have a significant effect on teacher "pupil control behavior." Alternative explanations for these findings are discussed. (EH)

  7. Pupil Control Behavior, Student Brinkmanship and Environmental Robustness.

    Science.gov (United States)

    Brown, Ralph E.; Licata, Joseph W.

    1978-01-01

    From the perspective of the student audience, the general results of the study suggest that, as teacher custodialism increases, the more robust are acts of student brinksmanship, the less robust is the teacher's pupil control behavior, and the less the teacher is liked by students. (Author)

  8. The Relationship between Pupil Control Ideology and Academic Optimism

    Science.gov (United States)

    Gilbert, Michael J.

    2012-01-01

    This study investigates the relationship between pupil control ideology and academic optimism. Information was generated through responses to a questionnaire emailed to teachers in two school districts in Central New Jersey. The districts were categorized GH, as determined by the State's district factor grouping. The research concludes that there…

  9. A Comparison of Middle School Teachers' Pupil Control Ideology

    Science.gov (United States)

    Jones, Paul; Garner, Arthur E.

    1978-01-01

    Compares pupil control ideology--discipline policy--of middle school classroom teachers with the intent of finding what attributes are needed for middle school teachers and the particular type classroom environment that facilitates optimum learning conditions for middle school children. (Author/RK)

  10. School Democratic Meetings: Pupil Control Discourse in Disguise

    Science.gov (United States)

    Thornberg, Robert

    2010-01-01

    The aim of this qualitative case study is to investigate how learning in "democratic participation" is constituted by the social interaction and conversation pattern in school democratic meetings in a Swedish primary school. According to the findings, a pupil control discourse and the Initiation-Response-Evaluation pattern dominates the…

  11. Pupil Control Ideology and Behavior as Predictors of Environmental Robustness: Public and Private Schools Compared.

    Science.gov (United States)

    Lunenburg, Fred C.

    1991-01-01

    Questionnaires examined differences between public and private schools regarding teachers' pupil control ideology and behavior. Teachers and students completed three survey instruments. Only pupil control ideology differed significantly between public and private schools. Pupil control behavior was the best predictor of environmental robustness.…

  12. A neural network method for detection of obstructive sleep apnea and narcolepsy based on pupil size and EEG.

    Science.gov (United States)

    Liu, D; Pang, Z; Lloyd, S R

    2008-02-01

    Electroencephalogram (EEG) is able to indicate states of mental activity ranging from concentrated cognitive efforts to sleepiness. Such mental activity can be reflected by EEG energy. In particular, intrusion of EEG theta wave activity into the beta activity of active wakefulness has been interpreted as ensuing sleepiness. Pupil behavior can also provide information regarding alertness. This paper develops an innovative signal classification method that is capable of differentiating subjects with sleep disorders which cause excessive daytime sleepiness (EDS) from normal control subjects who do not have a sleep disorder based on EEG and pupil size. Subjects with sleep disorders include persons with untreated obstructive sleep apnea (OSA) and narcolepsy. The Yoss pupil staging rule is used to scale levels of wakefulness and at the same time theta energy ratios are calculated from the same 2-s sliding windows by Fourier or wavelet transforms. Then, an artificial neural network (NN) of modified adaptive resonance theory (ART2) is utilized to identify the two groups within a combined group of subjects including those with OSA and healthy controls. This grouping from the NN is then compared with the actual diagnostic classification of subjects as OSA or controls and is found to be 91% accurate in differentiating between the two groups. The same algorithm results in 90% correct differentiation between narcoleptic and control subjects.

  13. Cognitive effort and pupil dilation in controlled and automatic processes

    Science.gov (United States)

    Querino, Emanuel; dos Santos, Lafaiete; Ginani, Giuliano; Nicolau, Eduardo; Miranda, Débora; Romano-Silva, Marco; Malloy-Diniz, Leandro

    2015-01-01

    The Five Digits Test (FDT) is a Stroop paradigm test that aims to evaluate executive functions. It is composed of four parts, two of which are related to automatic and two of which are related to controlled processes. It is known that pupillary diameter increases as the task’s cognitive demand increases. In the present study, we evaluated whether the pupillary diameter could distinguish cognitive effort between automated and controlled cognitive processing during the FDT as the task progressed. As a control task, we used a simple reading paradigm with a similar visual aspect as the FDT. We then divided each of the four parts into two blocks in order to evaluate the differences between the first and second half of the task. Results indicated that, compared to a control task, the FDT required higher cognitive effort for each consecutive part. Moreover, the first half of every part of the FDT induced dilation more than the second. The differences in pupil dilation during the first half of the four FDT parts were statistically significant between the parts 2 and 4 (p=0.023), and between the parts 3 and 4 (p=0.006). These results provide further evidence that cognitive effort and pupil diameter can distinguish controlled from automatic processes.

  14. Cognitive effort and pupil dilation in controlled and automatic processes.

    Science.gov (United States)

    Querino, Emanuel; Dos Santos, Lafaiete; Ginani, Giuliano; Nicolau, Eduardo; Miranda, Débora; Romano-Silva, Marco; Malloy-Diniz, Leandro

    2015-01-01

    The Five Digits Test (FDT) is a Stroop paradigm test that aims to evaluate executive functions. It is composed of four parts, two of which are related to automatic and two of which are related to controlled processes. It is known that pupillary diameter increases as the task's cognitive demand increases. In the present study, we evaluated whether the pupillary diameter could distinguish cognitive effort between automated and controlled cognitive processing during the FDT as the task progressed. As a control task, we used a simple reading paradigm with a similar visual aspect as the FDT. We then divided each of the four parts into two blocks in order to evaluate the differences between the first and second half of the task. Results indicated that, compared to a control task, the FDT required higher cognitive effort for each consecutive part. Moreover, the first half of every part of the FDT induced dilation more than the second. The differences in pupil dilation during the first half of the four FDT parts were statistically significant between the parts 2 and 4 (p=0.023), and between the parts 3 and 4 (p=0.006). These results provide further evidence that cognitive effort and pupil diameter can distinguish controlled from automatic processes.

  15. Vision correction for computer users based on image pre-compensation with changing pupil size.

    Science.gov (United States)

    Huang, Jian; Barreto, Armando; Alonso, Miguel; Adjouadi, Malek

    2011-01-01

    Many computer users suffer varying degrees of visual impairment, which hinder their interaction with computers. In contrast with available methods of vision correction (spectacles, contact lenses, LASIK, etc.), this paper proposes a vision correction method for computer users based on image pre-compensation. The blurring caused by visual aberration is counteracted through the pre-compensation performed on images displayed on the computer screen. The pre-compensation model used is based on the visual aberration of the user's eye, which can be measured by a wavefront analyzer. However, the aberration measured is associated with one specific pupil size. If the pupil has a different size during viewing of the pre-compensated images, the pre-compensation model should also be modified to sustain appropriate performance. In order to solve this problem, an adjustment of the wavefront function used for pre-compensation is implemented to match the viewing pupil size. The efficiency of these adjustments is evaluated with an "artificial eye" (high resolution camera). Results indicate that the adjustment used is successful and significantly improves the images perceived and recorded by the artificial eye.

  16. Teacher Pupil-Control Ideology and Behavior and Classroom Environmental Robustness.

    Science.gov (United States)

    Multhauf, Arleen P.; And Others

    1978-01-01

    Examines teacher's beliefs and behavior regarding pupil control and their impact on fourth, fifth, and sixth grade students' perceptions of classroom life. Research indicates that humanistic teacher pupil-control behavior is associated with students' reports of high classroom robustness. Inconsistencies between male ideology and behavior are…

  17. Pupil Control Ideology and Behavior and the Quality of School Life.

    Science.gov (United States)

    Lunenburg, Frederick C.; Schmidt, Linda J.

    More information is needed about the quality of school life, especially as it affects students' attitudes toward school. This paper contrasts pupil control ideologies and the types of school climates they engender in order to determine their effects on the quality of school life. Pupil control ideology and teacher behavior are conceptualized along…

  18. A Study of Pupil Control Ideology: A Person-Oriented Approach to Data Analysis

    Science.gov (United States)

    Adwere-Boamah, Joseph

    2010-01-01

    Responses of urban school teachers to the Pupil Control Ideology questionnaire were studied using Latent Class Analysis. The results of the analysis suggest that the best fitting model to the data is a two-cluster solution. In particular, the pupil control ideology of the sample delineates into two clusters of teachers, those with humanistic and…

  19. Effects of aniseikonia, anisometropia, accommodation, retinal illuminance, and pupil size on stereopsis.

    Science.gov (United States)

    Lovasik, J V; Szymkiw, M

    1985-05-01

    The sensitivity of clinical measures of stereoacuity in the detection of interocular differences in retinal images was examined in 50 adults with normal binocularity. Interocular differences in retinal image size (aniseikonia), clarity (anisometropia) and brightness, as well as differences in absolute and relative pupil size (anisocoria) were created in small steps over a large range to determine their effect on threshold levels of stereopsis. Their effect on stereoacuity was measured in both contour (Titmus test) and random dot (Randot test) stereograms. Stereoacuity measured by both types of stereograms decreased in a curvilinear manner for aniseikonic and anisometropic test conditions. Monocular blur caused a more rapid decrease in stereoacuity than induced aniseikonia. Stereoacuity measured by the contour stereogram decreased about 1.8 times faster than that measured by the random dot stereogram during induced aniseikonia and anisometropia. This differential sensitivity suggests that the Titmus test would detect small interocular differences in retinal images more effectively than the Randot test in clinical screening procedures for vision abnormalities. However, both tests can miss clinically significant amounts of aniseikonia and anisometropia, and fail to differentiate the cause of reduced stereopsis. Interocular differences in retinal image brightness and pupil size within a normal physiologic range did not reduce stereopsis to clinically unacceptable levels.

  20. The Relationship Between Student Alienation and Extent of Faculty Agreement on Pupil Control Ideology.

    Science.gov (United States)

    Shearin, Wiley H., Jr.

    1982-01-01

    Results supported hypothesis that schools with high agreement among staff on pupil control ideology would have less student alienation than those schools with low agreement. A 20-item, multiple-choice instrument was used to measure humanistic or custodial teacher orienation and the Kolesar's Pupil Attitude Questionnaire (PAQ) to measure student…

  1. Eyes wide open: Pupil size as a proxy for inhibition in the masked-priming paradigm.

    Science.gov (United States)

    Geller, Jason; Still, Mary L; Morris, Alison L

    2016-05-01

    A core assumption underlying competitive-network models of word recognition is that in order for a word to be recognized, the representations of competing orthographically similar words must be inhibited. This inhibitory mechanism is revealed in the masked-priming lexical-decision task (LDT) when responses to orthographically similar word prime-target pairs are slower than orthographically different word prime-target pairs (i.e., inhibitory priming). In English, however, behavioral evidence for inhibitory priming has been mixed. In the present study, we utilized a physiological correlate of cognitive effort never before used in the masked-priming LDT, pupil size, to replicate and extend behavioral demonstrations of inhibitory effects (i.e., Nakayama, Sears, & Lupker, Journal of Experimental Psychology: Human Perception and Performance, 34, 1236-1260, 2008, Exp. 1). Previous research had suggested that pupil size is a reliable indicator of cognitive load, making it a promising index of lexical inhibition. Our pupillometric data replicated and extended previous behavioral findings, in that inhibition was obtained for orthographically similar word prime-target pairs. However, our response time data provided only a partial replication of Nakayama et al. Journal of Experimental Psychology: Human Perception and Performance, 34, 1236-1260, 2008. These results provide converging lines of evidence that inhibition operates in word recognition and that pupillometry is a useful addition to word recognition researchers' toolbox.

  2. Teacher Pupil-Control Ideology and Behavior as Predictors of Classroom Environment: Public and Catholic Schools Compared. Draft.

    Science.gov (United States)

    Lunenburg, Fred C.

    This study examined differences between public and Catholic schools concerning teachers' pupil control ideology, teachers' pupil control behavior, and students' perceptions of their classroom environments. The concepts of humanistic and custodial pupil control ideologies were used to contrast types of individual orientations and the types of…

  3. Pupil Control Behavior, Classroom Robustness, and Self-Control: Public and Military Secondary Schools.

    Science.gov (United States)

    Sartori, Mary Ann; Bauske, Terri; Lunenburg, Fred C.

    2000-01-01

    Investigated students' perceptions of teachers pupil-control behavior, classroom robustness, and student self-control, highlighting possible differences between public and military secondary schools. Humanistic approaches had more positive, interrelated effects among these variables. Military (custodial) classrooms were perceived as less robust,…

  4. Effect of the hypomagnetic field on the size of the eye pupil

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    Binhi, Vladimir N

    2013-01-01

    Previously, we reported that the hypomagnetic field obtained by the 100-fold deprivation of the geomagnetic field affected human cognitive processes as estimated in several computer tests. The exposure to the hypomagnetic field caused a statistically significant increase both in the task processing time and in the number of errors. The magnitude of this magnetic effect, averaged over 40 healthy subjects and more than 10^5 separate trials, was about 1.7%. In the present work, the results of a simultaneous study are described, in which the right eye of each subject was video recorded, while the subject performed the tasks. It has appeared that the pupil size grows in the hypomagnetic field. This effect has been calculated based on the treatment of a large data set of about 6.10^6 video frames. Averaged all over the frames, the magnetic effect on the pupil area was about 1.6%, with high statistical confidence. This is the first laboratory study in which the number of separate trials has been large enough to obta...

  5. Emotional signals from faces, bodies and scenes influence observers' face expressions, fixations and pupil-size.

    Science.gov (United States)

    Kret, Mariska E; Roelofs, Karin; Stekelenburg, Jeroen J; de Gelder, Beatrice

    2013-01-01

    We receive emotional signals from different sources, including the face, the whole body, and the natural scene. Previous research has shown the importance of context provided by the whole body and the scene on the recognition of facial expressions. This study measured physiological responses to face-body-scene combinations. Participants freely viewed emotionally congruent and incongruent face-body and body-scene pairs whilst eye fixations, pupil-size, and electromyography (EMG) responses were recorded. Participants attended more to angry and fearful vs. happy or neutral cues, independent of the source and relatively independent from whether the face body and body scene combinations were emotionally congruent or not. Moreover, angry faces combined with angry bodies and angry bodies viewed in aggressive social scenes elicited greatest pupil dilation. Participants' face expressions matched the valence of the stimuli but when face-body compounds were shown, the observed facial expression influenced EMG responses more than the posture. Together, our results show that the perception of emotional signals from faces, bodies and scenes depends on the natural context, but when threatening cues are presented, these threats attract attention, induce arousal, and evoke congruent facial reactions.

  6. Salient cues from faces, bodies and scenes influence observers’ face expressions, fixations and pupil size

    Directory of Open Access Journals (Sweden)

    Mariska Esther Kret

    2013-12-01

    Full Text Available We receive emotional signals from different sources, including the face, the whole body and the natural scene. Previous research has shown the importance of context provided by the whole body and the scene context on the recognition of facial expressions. This study measured physiological responses to face-body-scene combinations. Participants viewed emotionally (incongruent face-body and body-scene pairs whilst eye fixations, pupil-size and electromyography (EMG responses were recorded. Participants focused more on angry and fearful vs. happy or neutral cues, independent of the source and relatively independent from emotional incongruence. Moreover, angry faces combined with angry bodies and angry bodies viewed in an aggressive social scene context elicited greatest pupil dilation. Participants' face expressions matched the valence of the stimuli but when face-body compounds were shown, the observed facial expression influenced EMG responses more than the postures. Our results show that threatening signals from faces, bodies and scenes attract attention, induce arousal, and evoke congruent facial reactions.

  7. Time Course of Pupil Center Location after Ocular Drug Application.

    Science.gov (United States)

    Hoang, Tony A; Macdonnell, Jacqueline E; Mangan, Michelle C; Monsour, Cindy S; Polwattage, Buddhika L; Wilson, Sarah F; Suheimat, Marwan; Atchison, David A

    2016-06-01

    To investigate the time course of pupil centration after application of common topical ocular drugs. Single drops of 2.5% phenylephrine hydrochloride, 1% tropicamide, and 2% pilocarpine hydrochloride were applied on different days to the right eyes of 12 participants. Anterior eye images were captured, at 5-min intervals for an hour, using an infrared-sensitive camera. The images were analyzed to determine pupil diameter and pupil center, the latter with respect to the limbal center. As a control, natural pupil size and pupil center were determined under different illuminances. Pupil centers of natural pupils shifted temporally as pupils dilated. At common pupil sizes, drug-induced pupil centers were different from natural pupil centers. Phenylephrine produced a center shift in the nasal and inferior directions that peaked after a mean of 30 min, whereas dilation was continuing up to 60 min. Tropicamide produced transient center shifts in the nasal and inferior directions that peaked at about 10 min before reducing toward baseline values, whereas dilation reached a peak at about 25 min. Pilocarpine produced a small sustained superior shift that, like constriction, reached a peak after about 25 min. Application of topical ophthalmic drugs cause shifts in pupil center that do not match those produced by natural changes in pupil size and that, in the cases of phenylephrine and tropicamide, follow a different time course than the pupil size changes.

  8. Summary of an Analysis of Pupil-Teacher Ratio and Class Size: Differences That Make a Difference and Its Implications on Staffing for Class-Size Reduction.

    Science.gov (United States)

    Sharp, Mark A.

    The purpose of this paper was to share findings from an earlier study and to provide a framework for administrators to use in the implementation of class-size reduction (CSR) in their buildings. The study examined actual and average class size (CS), pupil-teacher ratios (PTR), and their differences. A primary goal was to clarify the ramifications…

  9. Students' Perceptions of Ideal and Actual Teacher Pupil Control Behavior and Reading Achievement.

    Science.gov (United States)

    Forlenza, Vito A.; Willower, Donald J.

    1980-01-01

    Tests the hypothesis that student reading achievement will be a function of the congruence of student's perception of actual and ideal teacher pupil-control behavior. Subjects were 231 students in nine sixth-grade classrooms. (MP)

  10. Pupils' Self-Perceptions: The Role of Teachers' Judgment Controlling for Big-Fish-Little-Pond Effect

    Science.gov (United States)

    Bressoux, Pascal; Pansu, Pascal

    2016-01-01

    This article aims to study the relationship between teachers' judgment and pupils' self-perceptions controlling for the big-fish-little-pond effect (BFLPE). Three studies were conducted among third-grade pupils. Study 1 (n = 585) focused on pupils' perceptions of their scholastic competence. Teachers' judgment and BFLPE were found to have an…

  11. The Effects of Multimedia Learning on Thai Primary Pupils' Achievement in Size and Depth of Vocabulary Knowledge

    Science.gov (United States)

    Jingjit, Mathukorn

    2015-01-01

    This study aims to obtain more insight regarding the effect of multimedia learning on third grade of Thai primary pupils' achievement in Size and Depth Vocabulary of English. A quasi-experiment is applied using "one group pretest-posttest design" combined with "time series design," as well as data triangulation. The sample…

  12. Effects of pirenzepine on pupil size and accommodation in rhesus monkeys.

    Science.gov (United States)

    Ostrin, Lisa A; Frishman, Laura J; Glasser, Adrian

    2004-10-01

    Pirenzepine is suggested to be a relatively selective muscarinic (M(1)) antagonist and is currently under investigation for the treatment of myopia. Atropine, a nonselective M-type antagonist, is used in the treatment of myopia, but has undesired ocular and systemic side effects. An M(1)-specific antagonist may decrease side effects and remain effective at reducing the progression of myopia. In the current study, the effects of pirenzepine on pupil diameter, resting refraction, and accommodation were studied in rhesus monkeys. The time course and extent of mydriasis from subconjunctival injection of 2% pirenzepine were determined in five normal rhesus monkeys, and the effects on static and dynamic accommodation were determined in four rhesus monkeys with permanent indwelling electrodes in the Edinger-Westphal (EW) nucleus of the midbrain. Subconjunctival injections of 0.0002% to 0.2% pirenzepine in log unit dilutions were tested in three monkeys to determine the effects on static EW-stimulated accommodation. At 40 to 50 minutes after pirenzepine injection, accommodation was stimulated pharmacologically in both eyes, and the response was measured for 30 minutes. After 2% pirenzepine injection, pupil size increased 2.02 +/- 0.41 mm, there was a hyperopic shift in resting refraction of 1.07 +/- 0.23 D, and nearly complete cycloplegia occurred. Maximum EW-stimulated accommodation was significantly decreased 20 to 40 minutes after 0.02% or greater pirenzepine. Carbachol-stimulated accommodation was significantly decreased after 0.2% or greater pirenzepine. Subconjunctival injections of 0.02% or greater pirenzepine result in a significant decrease in accommodation and are probably acting through nonselective muscarinic antagonism. Subconjunctival injections of 0.002% or less pirenzepine do not decrease EW-stimulated accommodation.

  13. Primary school teachers’ views about pupil control ideologies and classroom management styles

    Directory of Open Access Journals (Sweden)

    Kürşad Yılmaz

    2009-12-01

    Full Text Available Classroom management is a critical competency area for all teachers because classroom management skills are directly relatedto pupil achievement. In the present study, the four-category (authoritarian, authoritative, laissez-faire, indifferentclassification of Kris (1997a is used. Pupil control ideologies, conceptualized by Willover, Eidell and Hoy (1967, were developedto define teachers’ views about pupil control. Pupil control ideologies conceptualized as two poles ranging from custodialcontrol ideology to humanistic control ideology. The purpose of the present study is to determine the correlation betweenprimary school teachers’ views about pupil control ideologies and classroom management styles. The survey model studyattempts to answer the research questions. 200 primary school teachers from Kütahya province are included in the sample ofthe research. The data is collected using “Classroom Management Profile Scale” and the “Pupil Control Ideology Scale”.Descriptive statistics and Pearson correlation analysis were used in data analysis. According to the findings obtained from thestudy, primary school teachers mostly presented authoritarian classroom management style, which was respectively followedby authoritative classroom management style, laissez-faire classroom management style and indifferent classroommanagement style. The findings of the study show that primary school teachers are closer to custodial control ideology. Acustodial control ideology has certain qualities such as strict control, enforcement of orders, one way downwardcommunication, and distrust towards pupils, cruel punishments and taking undisciplined behavior as personal offences. There isa moderate, positive and significant correlation between the participants’ views about custodial control ideologies andauthoritarian classroom management styles. It could be said from the findings of the study that the more the custodial controlideology of the participants

  14. Effect of Single Administration of Coffee on Pupil Size and Ocular Wavefront Aberration Measurements in Healthy Subjects

    Directory of Open Access Journals (Sweden)

    Handan Bardak

    2016-01-01

    Full Text Available No study has so far evaluated the impact of coffee drinking on ocular wavefront aberration (OWA measurements. This study presents novel findings regarding the OWA of the eye following coffee intake. We aimed to evaluate the acute changes in pupil size and OWA of the eye after single administration of coffee. A total of 30 otherwise healthy participants were included in this prospective study. All subjects drank a cup of coffee containing 57 mg caffeine. Measurements of pupil size, total coma (TC, total trefoil (TF, total spherical aberration (TSA, and total higher order aberration (HOA were performed before and at 5 minutes, at 30 minutes, and at 4 hours after coffee drinking using a wavefront aberrometer device (Irx3, Imagine Eyes, Orsay, France. The mean age of the study population was 20.30 ± 2.74 years. Pupil size did not show a significant change during the measurements (p>0.05. A significant increase was observed in TF and HOA measurements following coffee intake (p=0.029 and p=0.009, resp.. Single administration of coffee results in significant increase in TF and total HOAs in healthy subjects without any effect on pupil diameter. Ultrastructural changes in the cornea following coffee intake might be of relevance to the alterations in ocular aberrations in healthy subjects.

  15. Pupil size signals mental effort deployed during multiple object tracking and predicts brain activity in the dorsal attention network and the locus coeruleus.

    Science.gov (United States)

    Alnæs, Dag; Sneve, Markus Handal; Espeseth, Thomas; Endestad, Tor; van de Pavert, Steven Harry Pieter; Laeng, Bruno

    2014-04-01

    Attentional effort relates to the allocation of limited-capacity attentional resources to meet current task demands and involves the activation of top-down attentional systems in the brain. Pupillometry is a sensitive measure of this intensity aspect of top-down attentional control. Studies relate pupillary changes in response to cognitive processing to activity in the locus coeruleus (LC), which is the main hub of the brain's noradrenergic system and it is thought to modulate the operations of the brain's attentional systems. In the present study, participants performed a visual divided attention task known as multiple object tracking (MOT) while their pupil sizes were recorded by use of an infrared eye tracker and then were tested again with the same paradigm while brain activity was recorded using fMRI. We hypothesized that the individual pupil dilations, as an index of individual differences in mental effort, as originally proposed by Kahneman (1973), would be a better predictor of LC activity than the number of tracked objects during MOT. The current results support our hypothesis, since we observed pupil-related activity in the LC. Moreover, the changes in the pupil correlated with activity in the superior colliculus and the right thalamus, as well as cortical activity in the dorsal attention network, which previous studies have shown to be strongly activated during visual tracking of multiple targets. Follow-up pupillometric analyses of the MOT task in the same individuals also revealed that individual differences to cognitive load can be remarkably stable over a lag of several years. To our knowledge this is the first study using pupil dilations as an index of attentional effort in the MOT task and also relating these to functional changes in the brain that directly implicate the LC-NE system in the allocation of processing resources.

  16. Analysis of illumination pupil filling ellipticity for critical dimensions control in photolithography

    Institute of Scientific and Technical Information of China (English)

    Liping Guo; Xiangzhao Wang; Huijie Huang

    2006-01-01

    @@ Shrinking of critical dimensions (CDs) in semiconductor circuits has been pushing optical lithography to print features smaller than the wavelength of light source. The demand for CD control is ever-increasing.In this paper, the study is conducted to reveal the impact of illumination pupil filling ellipticity on CD uniformity. As main parameters of CD uniformity, horizontal-vertical feature bias (H-V bias) and isolateddense feature bias (I-D bias) caused by pupil filling ellipticity are calculated using the PROLITH softwaxe under four different illumination settings. Simulation shows that H-V bias and I-D bias are proportional to the pupil filling ellipticity. The slopes of the fitting lines of the H-V bias versus pupil filling ellipticity axe calculated.

  17. Pupil-size asymmetry is a physiologic trait related to gender, attentional function, and personality.

    Science.gov (United States)

    Poynter, William D

    2016-12-14

    A small difference in the size of the two pupils is common in healthy individuals, a condition termed benign or physiologic anisocoria (BA). Past research indicates that BA is probably caused by asymmetry in sympathetic nervous system (SNS) function [e.g., Rosenberg (2008). Physiologic anisocoria: A manifestation of a physiologic sympathetic asymmetry. Neuro-Ophthalmology, 32, 147-149]. This study is the first to show that BA varies with psychological factors linked to brain asymmetry and autonomic arousal, including gender, attention, and personality. Males exhibited a more directional BA than females, consistent with greater hemispheric lateralization in males. BA also varied with a self-report measure of attentional function, consistent with evidence of hemispheric asymmetry in visuospatial attention networks. Finally, BA varied with personality traits linked to autonomic arousal. Individuals exhibiting higher Meanness and Boldness, and lower Empathy scores tended to show more directional BA. This link between personality traits and BA may be related to brain asymmetries in autonomic arousal and emotion-related processing. If future studies employing direct measures of lateralized brain activity confirm the link between BA and SNS asymmetries, this new metric may prove useful in discovering new relationships between brain organization and psychological function, and how these relationships vary across individuals.

  18. An attempt to understand flicker vertigo: changes in pupil size and choroidal blood flow under flickering conditions

    Science.gov (United States)

    Masi, Maria Gabriella; Peretto, Lorenzo; Rovati, Luigi; Ansari, Rafat R.

    2010-02-01

    Light flickering at a rate of 4- 20 cycles per second can produce unpleasant reactions such as nausea and vertigo. In this paper, the possibility of achieving an objective evaluation/prediction of the physiological effects induced by flicker is investigated using a new imaging method based on the pupil size determination. This method is also compared with the blood flow analysis in the choroid.

  19. Influence of ocular chromatic aberration and pupil size on transverse resolution in ophthalmic adaptive optics optical coherence tomography.

    Science.gov (United States)

    Fernández, Enrique; Drexler, Wolfgang

    2005-10-03

    Optical coherence tomography (OCT) enables visualization of the living human retina with unprecedented high axial resolution. The transverse resolution of existing OCT approaches is relatively modest as compared to other retinal imaging techniques. In this context, the use of adaptive optics (AO) to correct for ocular aberrations in combination with OCT has recently been demonstrated to notably increase the transverse resolution of the retinal OCT tomograms. AO is required when imaging is performed through moderate and large pupil sizes. A fundamental difference of OCT as compared to other imaging techniques is the demand of polychromatic light to accomplish high axial resolution. In ophthalmic OCT applications, the performance is therefore also limited by ocular chromatic aberrations. In the current work, the effects of chromatic and monochromatic ocular aberrations on the quality of retinal OCT tomograms, especially concerning transverse resolution, sensitivity and contrast, are theoretically studied and characterized. The repercussion of the chosen spectral bandwidth and pupil size on the final transverse resolution of OCT tomograms is quantitatively examined. It is found that losses in the intensity of OCT images obtained with monochromatic aberration correction can be up to 80 %, using a pupil size of 8 mm diameter in combination with a spectral bandwidth of 120 nm full width at half maximum for AO ultrahigh resolution OCT. The limits to the performance of AO for correction of monochromatic aberrations in OCT are established. The reduction of the detected signal and the resulting transverse resolution caused by chromatic aberration of the human eye is found to be strongly dependent on the employed bandwidth and pupil size. Comparison of theoretical results with experimental findings obtained in living human eyes is also provided.

  20. Ocular accommodation and cognitive demand: An additional indicator besides pupil size and cardiovascular measures?

    Directory of Open Access Journals (Sweden)

    Jaschinski Wolfgang

    2008-08-01

    Full Text Available Abstract Background The aim of the present study was to assess accommodation as a possible indicator of changes in the autonomic balance caused by altered cognitive demand. Accounting for accommodative responses from a human factors perspective may be motivated by the interest of designing virtual image displays or by establishing an autonomic indicator that allows for remote measurement at the human eye. Heart period, pulse transit time, and the pupillary response were considered as reference for possible closed-loop accommodative effects. Cognitive demand was varied by presenting monocularly numbers at a viewing distance of 5 D (20 cm which had to be read, added or multiplied; further, letters were presented in a "n-back" task. Results Cardiovascular parameters and pupil size indicated a change in autonomic balance, while error rates and reaction time confirmed the increased cognitive demand during task processing. An observed decrease in accommodation could not be attributed to the cognitive demand itself for two reasons: (1 the cognitive demand induced a shift in gaze direction which, for methodological reasons, accounted for a substantial part of the observed accommodative changes. (2 Remaining effects disappeared when the correctness of task processing was taken into account. Conclusion Although the expectation of accommodation as possible autonomic indicator of cognitive demand was not confirmed, the present results are informative for the field of applied psychophysiology noting that it seems not to be worthwhile to include closed-loop accommodation in future studies. From a human factors perspective, expected changes of accommodation due to cognitive demand are of minor importance for design specifications – of, for example, complex visual displays.

  1. Threat but not arousal narrows attention: Evidence from pupil dilation and saccade control

    Directory of Open Access Journals (Sweden)

    Henk eVan Steenbergen

    2011-10-01

    Full Text Available It has been shown that negative affect causes attentional narrowing. According to Easterbrook’s (1959 influential hypothesis this effect is driven by the withdrawal motivation inherent to negative emotions and might be related to increases in arousal. We investigated whether valence-unspecific increases in physiological arousal, as measured by pupil dilation, could account for attentional narrowing effects in a cognitive control task. Following the presentation of a negative, positive, or neutral picture, participants performed a saccade task with a prosaccade versus an antisaccade instruction. The reaction time difference between pro- and antisaccades was used to index attentional selectivity, and while pupil diameter was used as an index of physiological arousal. Pupil dilation was observed for both negative and positive pictures, which indicates increased physiological arousal. However, increased attentional selectivity was only observed following negative pictures. Our data show that motivational intensity effects on attentional narrowing can occur independently of physiological arousal effects.

  2. Pupil Center as a Function of Pupil Diameter

    DEFF Research Database (Denmark)

    Ahmed, Zaheer; Mardanbegi, Diako; Hansen, Dan Witzner

    2016-01-01

    We investigate the gaze estimation error induced by pupil size changes using simulated data. We investigate the influence of pupil diameter changes on estimated gaze point error obtained by two gaze estimation models. Simulation data show that at wider viewing angles and at small eye......-camera distances, error increases with increasing pupil sizes. The maximum error recorded for refracted pupil images is 2.4° of visual angle and 1.5° for non-refracted pupil projections....

  3. Cell-Size Control

    Science.gov (United States)

    Amodeo, Amanda A.; Skotheim, Jan M.

    2015-01-01

    Cells of a given type maintain a characteristic cell size to function efficiently in their ecological or organismal context. They achieve this through the regulation of growth rates or by actively sensing size and coupling this signal to cell division. We focus this review on potential size-sensing mechanisms, including geometric, external cue, and titration mechanisms. Mechanisms that titrate proteins against DNA are of particular interest because they are consistent with the robust correlation of DNA content and cell size. We review the literature, which suggests that titration mechanisms may underlie cell-size sensing in Xenopus embryos, budding yeast, and Escherichia coli, whereas alternative mechanisms may function in fission yeast. PMID:26254313

  4. Bureaucracy and Pupil Control Orientation and Behavior in Urban Secondary Schools.

    Science.gov (United States)

    Lunenburg, Fred C.; Mankowsky, Scarlett A.

    Data collected from 297 teachers and 7,376 students in 20 urban high schools were used to examine relationships between dimensions of bureaucratic structure and pupil control orientation and behavior. Results of the analyses revealed two distinct patterns of rational organization. Hierarchy, rules, impersonality, and centralization comprised the…

  5. Teacher's Sense of Power and the Consistency of Their Pupil Control Ideology and Behavior.

    Science.gov (United States)

    Rose, Keith R.; Willower, Donald J.

    1981-01-01

    Responses from a sample of 71 secondary teachers and 1,272 students were consistent with the hypothesis that teachers' sense of power would be directly associated with the consistency of their beliefs and behavior concerning pupil control. Some speculations were advanced concerning additional influences on teacher belief-behavior consistency. (NEC)

  6. Personality Characteristics and Self-Concept of Preservice Teachers Related to Their Pupil Control Orientation.

    Science.gov (United States)

    Halpin, Glennelle; And Others

    1982-01-01

    In a study of teacher trainees' personality characteristics related to pupil control, humanistically oriented educators tended to be emotionally stable, expedient, positive, imaginative, venturesome, relaxed and had high self-concepts. Authoritarian educators were more affected by feelings, conscientious, sober, practical, shy, reserved, tense and…

  7. CSCL for Intellectually Disabled Pupils: Stimulating Interaction by Using a Floor Control Mechanism

    Science.gov (United States)

    Cress, Ulrike; Wodzicki, Katrin; Bientzle, Martina; Lingnau, Andreas

    2011-01-01

    Computer-supported collaborative learning has an unexploited potential of becoming an effective learning method for pupils with intellectual disabilities. This paper aims at showing how some specific requirements of this target group may be met by structuring a learning situation with the help of "floor control," which restricts the opportunities…

  8. The effect of pupil size on stimulation of the melanopsin containing retinal ganglion cells, as evaluated by monochromatic pupillometry

    DEFF Research Database (Denmark)

    Nissen, Claus Jeppe; Sander, Birgit; Lund-Andersen, Henrik

    2012-01-01

    Purpose: To evaluate the influence of the size of the light exposed pupil in one eye on the pupillary light reflex of the other eye. Method: Using a monochromatic pupillometer, the left eye in each of 10 healthy subjects was exposed to 20¿s of monochromatic light of luminance 300¿cd/m(2), first red...... (660¿nm) and in a following session, blue (470¿nm) light. The consensual pupillary diameter in the right eye was continuously measured before, during, and after light exposure. Subsequently, Tropicamide 1% or Pilocarpine 2% was instilled into the left eye and when the pupil was either maximally dilated...... or contracted, the entire sequence of red and blue light exposure repeated. After at least 3¿days, when the effect of the eye drop had subsided, the entire experiment was repeated, this time employing the other substance. Results: Prior dilatation of the left pupil augmented the post light contraction to blue...

  9. Effective pupil dilatation with a mixture of 0.75% tropicamide and 2.5% phenylephrine: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Trinavarat Adisak

    2009-01-01

    Full Text Available Purpose: To compare the efficacy in pupil dilatation between a mixture containing 0.75% tropicamide and 2.5% phenylephrine and the alternate application of 1% tropicamide and 10% phenylephrine eye drops. Material and Methods : Patients requiring pupil dilatation were randomized to receive one drop of the mixture every 10 min for four times or our standard application of one drop of 1% tropicamide alternating with one drop of 10% phenylephrine every 10 min for two cycles. Pupil size was measured under bright light with the pupil gauge before, and every 5 min after initial application for 40 min. Application of the drops was discontinued once the pupil diameter reached 7 mm. Blood pressure and pulse rate were monitored every 15 min. Results: Of 40 patients (age 57.3±10.9 years, range 35-70 years, 22 were randomized into the mixture group and 18 into the alternate drug group. Baseline pupil sizes were 1.7±0.5 mm in the mixture group and 1.8±0.4 mm in the alternate drug group. The pupils were successfully dilated to 7 mm within 40 min in 17 patients of the mixture group compared to seven patients in the alternate drug group ( P =0.004, Log Rank test. The mean pupil sizes at 40 min were 6.6±0.8 and 6.0±0.9 mm in the mixture and alternate drug groups respectively ( P =0.050, t-test. Blood pressure and pulse rate were stable and similar in both groups. Conclusions: The mixture of 0.75% tropicamide and 2.5% phenylephrine is superior to our standard application of 1% tropicamide alternating with 10% phenylephrine. It provides faster and more successful pupil dilatation within 40 min.

  10. Tourette Syndrome: Complementary Insights from Measures of Cognitive Control, Eyeblink Rate, and Pupil Diameter

    Science.gov (United States)

    Tharp, Jordan A.; Wendelken, Carter; Mathews, Carol A.; Marco, Elysa J.; Schreier, Herbert; Bunge, Silvia A.

    2015-01-01

    Some individuals with Tourette syndrome (TS) have severe motoric and vocal tics that interfere with all aspects of their lives, while others have mild tics that pose few problems. We hypothesize that observed tic severity reflects a combination of factors, including the degree to which dopaminergic (DA) and/or noradrenergic (NE) neurotransmitter systems have been affected by the disorder, and the degree to which the child can exert cognitive control to suppress unwanted tics. To explore these hypotheses, we collected behavioral and eyetracking data from 26 patients with TS and 26 controls between ages 7 and 14, both at rest and while they performed a test of cognitive control. To our knowledge, this is the first study to use eyetracking measures in patients with TS. We measured spontaneous eyeblink rate as well as pupil diameter, which have been linked, respectively, to DA and NE levels in the central nervous system. Here, we report a number of key findings that held when we restricted analyses to unmedicated patients. First, patients’ accuracy on our test of cognitive control accounted for fully 50% of the variance in parentally reported tic severity. Second, patients exhibited elevated spontaneous eyeblink rates compared to controls, both during task performance and at rest, consistent with heightened DA transmission. Third, although neither task-evoked pupil dilation nor resting pupil diameter differed between TS patients and controls, pupil diameter was positively related to parentally reported anxiety levels in patients, suggesting heightened NE transmission in patients with comorbid anxiety. Thus, with the behavioral and eyetracking data gathered from a single task, we can gather objective data that are related both to tic severity and anxiety levels in pediatric patients with TS, and that likely reflect patients’ underlying neurochemical disturbances. PMID:26175694

  11. Teacher Pupil Control Ideology and Behavior and Classroom Environmental Robustness.

    Science.gov (United States)

    Willower, Donald J.; And Others

    Two hypotheses were tested investigating the relationship between beliefs and behaviors of teachers in controlling students and student perceptions of classroom excitement. It was hypothesized that direct relationships would exist between teacher strictness in beliefs and behaviors toward student control and the students' opinions concerning the…

  12. Human place and response learning: navigation strategy selection, pupil size and gaze behavior.

    Science.gov (United States)

    de Condappa, Olivier; Wiener, Jan M

    2016-01-01

    In this study, we examined the cognitive processes and ocular behavior associated with on-going navigation strategy choice using a route learning paradigm that distinguishes between three different wayfinding strategies: an allocentric place strategy, and the egocentric associative cue and beacon response strategies. Participants approached intersections of a known route from a variety of directions, and were asked to indicate the direction in which the original route continued. Their responses in a subset of these test trials allowed the assessment of strategy choice over the course of six experimental blocks. The behavioral data revealed an initial maladaptive bias for a beacon response strategy, with shifts in favor of the optimal configuration place strategy occurring over the course of the experiment. Response time analysis suggests that the configuration strategy relied on spatial transformations applied to a viewpoint-dependent spatial representation, rather than direct access to an allocentric representation. Furthermore, pupillary measures reflected the employment of place and response strategies throughout the experiment, with increasing use of the more cognitively demanding configuration strategy associated with increases in pupil dilation. During test trials in which known intersections were approached from different directions, visual attention was directed to the landmark encoded during learning as well as the intended movement direction. Interestingly, the encoded landmark did not differ between the three navigation strategies, which is discussed in the context of initial strategy choice and the parallel acquisition of place and response knowledge.

  13. Phase and Pupil Amplitude Recovery for JWST Space-Optics Control

    Science.gov (United States)

    Dean, B. H.; Zielinski, T. P.; Smith, J. S.; Bolcar, M. R.; Aronstein, D. L.; Fienup, J. R.

    2010-01-01

    This slide presentation reviews the phase and pupil amplitude recovery for the James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam). It includes views of the Integrated Science Instrument Module (ISIM), the NIRCam, examples of Phase Retrieval Data, Ghost Irradiance, Pupil Amplitude Estimation, Amplitude Retrieval, Initial Plate Scale Estimation using the Modulation Transfer Function (MTF), Pupil Amplitude Estimation vs lambda, Pupil Amplitude Estimation vs. number of Images, Pupil Amplitude Estimation vs Rotation (clocking), and Typical Phase Retrieval Results Also included is information about the phase retrieval approach, Non-Linear Optimization (NLO) Optimized Diversity Functions, and Least Square Error vs. Starting Pupil Amplitude.

  14. How Class Size Reduction Mediates Secondary Students' Learning: Hearing the Pupil Voice

    Science.gov (United States)

    Harfitt, Gary James

    2012-01-01

    This paper discusses the question of why and how class size can make a difference to teaching and learning from the students' perspective. Secondary school contexts and, in particular, the students' own voice on the issue of class size represent an under-researched area for class size studies. This paper draws on data from three case studies that…

  15. Optimal timing of retinal scanning during dark adaptation, in the presence of fixation on a target: the role of pupil size dynamics

    Science.gov (United States)

    Gramatikov, Boris I.; Irsch, Kristina; Guyton, David

    2014-10-01

    While validating our newly developed vision screener based on a double-pass retinal scanning system, we noticed that in all patients the signals from the retina were significantly higher when measurements were performed within a certain time interval referenced to the initial moment when the lights were dimmed and the test subject was asked to fixate on a target. This appeared to be most likely attributable to pupil size dynamics and triggered the present study, whose aim was to assess the pupillary "lights-off" response while fixating on a target in the presence of an accommodative effort. We found that pupil size increases in the first 60 to 70 s after turning off the room lights, and then it decreases toward the baseline in an exponential decay. Our results suggest that there is an optimal time window during which pupil size is expected to be maximal, that is during the second minute after dimming the room lights. During this time, window retinal diagnostic instruments based on double-pass measurement technology should deliver an optimal signal-to-noise ratio. We also propose a mathematical model that can be used to approximate the behavior of the normalized pupil size.

  16. Nevada's Class-Size Reduction Program. Nevada Revised Statutes 388.700-388.730: "Program To Reduce the Pupil-Teacher Ratio." Background Paper 97-7.

    Science.gov (United States)

    Sturm, H. Pepper

    In 1989, the Nevada Legislature enacted the Class-Size Reduction (CSR) Act. The measure was designed to reduce the pupil-teacher ratio in the public schools, particularly in the earliest grades. The program was scheduled to proceed in several phases. The first step reduced the student-teacher ratio in selected kindergartens and first grade classes…

  17. Optimal timing of retinal scanning during dark adaptation, in the presence of fixation on a target: the role of pupil size dynamics.

    Science.gov (United States)

    Gramatikov, Boris I; Irsch, Kristina; Guyton, David

    2014-01-01

    While validating our newly developed vision screener based on a double-pass retinal scanning system, we noticed that in all patients the signals from the retina were significantly higher when measurements were performed within a certain time interval referenced to the initial moment when the lights were dimmed and the test subject was asked to fixate on a target. This appeared to be most likely attributable to pupil size dynamics and triggered the present study, whose aim was to assess the pupillary “lights-off” response while fixating on a target in the presence of an accommodative effort. We found that pupil size increases in the first 60 to 70 s after turning off the room lights, and then it decreases toward the baseline in an exponential decay. Our results suggest that there is an optimal time window during which pupil size is expected to be maximal, that is during the second minute after dimming the room lights. During this time, window retinal diagnostic instruments based on double-pass measurement technology should deliver an optimal signal-to-noise ratio. We also propose a mathematical model that can be used to approximate the behavior of the normalized pupil size.

  18. Beam control for LINC-NIRVANA: from the binocular entrance pupil to the combined focal plane

    Science.gov (United States)

    Bertram, T.; Trowitzsch, J.; Herbst, T. M.; Ragazzoni, R.

    2012-07-01

    LINC-NIRVANA is the near-infrared interferometric imaging camera for the Large Binocular Telescope. Once operational, it will provide an unprecedented combination of angular resolution, sensitivity and field of view. To meet the tight requirements that result from long exposure interferometric imaging over a large field of view, active control beyond fringe tracking and adaptive optics has to be in place in the telescope and in the instrument domain. The incoming beams of the binocular telescope have to be controlled along the entire optical path, from the entrance pupil to the combined focal plane. The beams have to coincide in the focal plane of the science detector, their pointing origins, offsets, orientations, plate scales, and distortions have to match each other and must not change during the observation. Non-common path effects between AO and science channel, flexure and thermal effects have to be compensated and offioading requests from the adaptive optics and fringe tracking systems have to be arbitrated without introducing unwanted optical path length differences or changes in the geometry of the binocular entrance pupil. Beam Control aspects include pointing, co-pointing and field derotation, active optics and collimation control. In this presentation, the constraints for coherent imaging over a 1.5 arcminute field of view are discussed together with a concept for a distributed control scheme.

  19. Teacher-Pupil Relationships: Black Students' Perceptions of Actual and Ideal Teacher/Pupil Control Behavior and Attitudes Toward Teachers and School

    Science.gov (United States)

    Sweeting, Lurlene M.; And Others

    1978-01-01

    Regardless of the direction of pupils' preferences (humanistic or custodial) the more closely pupils' perceptions of their teachers' actual behavior approximated their conception of ideal teacher behavior, the more positive were their attitudes toward teacher and school. (Author)

  20. The relationship of pupil control to preservice elementary science teacher self-efficacy and outcome expectancy

    Science.gov (United States)

    Enochs, Larry G.; Scharmann, Lawrence C.; Riggs, Iris M.

    The investigators' intentions in this study were to examine preservice elementary teachers' sense of self-efficacy with regard to science teaching and to define the construct of self-efficacy with greater clarity. Additionally, the construct of pupil control was examined. To gather information toward these purposes, we investigated the following questions: Do prospective elementary teachers' efficacy beliefs relate to their beliefs concerning classroom management or control?; and How is a measure of self-efficacy related to prospective teachers' self-reported choice concerning the teaching of science, amount of time spent in performing hands-on science, and/or perceived effectiveness as future elementary science teachers? Self-efficacy was measured as two distinct constructs, personal self-efficacy and outcome expectancy. Significant correlations were found between personal science teaching self-efficacy and (1) the number of college science courses taken; (2) the number of years of high school science taken; (3) respondent's choice of science instructional delivery; and (4) respondent's perceived effectiveness in teaching science. When the outcome expectancy subscale is considered, however, only one significant correlation is indicated; perceived effectiveness in teaching science was significantly correlated with outcome expectancy. Personal science teaching self-efficacy was significantly correlated with pupil control ideology while outcome expectancy was not.

  1. Pupil diameter tracks changes in control state predicted by the adaptive gain theory of locus coeruleus function.

    Science.gov (United States)

    Gilzenrat, Mark S; Nieuwenhuis, Sander; Jepma, Marieke; Cohen, Jonathan D

    2010-05-01

    An important dimension of cognitive control is the adaptive regulation of the balance between exploitation (pursuing known sources of reward) and exploration (seeking new ones) in response to changes in task utility. Recent studies have suggested that the locus coeruleus-norepinephrine system may play an important role in this function and that pupil diameter can be used to index locus coeruleus activity. On the basis of this, we reasoned that pupil diameter may correlate closely with control state and associated changes in behavior. Specifically, we predicted that increases in baseline pupil diameter would be associated with decreases in task utility and disengagement from the task (exploration), whereas reduced baseline diameter (but increases in task-evoked dilations) would be associated with task engagement (exploitation). Findings in three experiments were consistent with these predictions, suggesting that pupillometry may be useful as an index of both control state and, indirectly, locus coeruleus function.

  2. Teachers' Experiences of Using Eye Gaze-Controlled Computers for Pupils with Severe Motor Impairments and without Speech

    Science.gov (United States)

    Rytterström, Patrik; Borgestig, Maria; Hemmingsson, Helena

    2016-01-01

    The purpose of this study is to explore teachers' experiences of using eye gaze-controlled computers with pupils with severe disabilities. Technology to control a computer with eye gaze is a fast growing field and has promising implications for people with severe disabilities. This is a new assistive technology and a new learning situation for…

  3. The effect of intracameral epinephrine on pupil size during phacoemulsification and its postoperative effect on specular findings and macular thickness

    Directory of Open Access Journals (Sweden)

    Hassan Gamal El-Din Farahat

    Full Text Available ABSTRACT Objective: To evaluate pupillary size and vital signs following intraoperative intracameral adrenaline during phacoemulsification and postoperative effect of on co specular microscopy findings and macular thickness by OCT. Methods: A prospective interventional study carried out from December 2014 to December 2015 on 90 eyes. They were divided randomly into further 6 groups (15 each. The inclusion criteria consisted of no history of ocular pathologic conditions, trauma, previous ocular surgery, or recent ocular medication use. All patients were dilated preoperatively by phenylephrine 10% and operated under local peribulbar anesthesia. Then systemic monitoring regarding (pulse rate, blood pressure and measurement of the horizontal pupil diameter by a caliper to the nearest 0.25mm pre and post intracameral adrenaline injection. Results: In our study there were great effect for intracameral epinephrine, with concentrations used, in dilatation and maintainance of papillary dilatation, The mean pre intracameral epinephrine was 4.53± 1.27 mm.The mean post epinephrine papillary diameter was 6.46± 1.00 mm. Three cases from group 1/10000 weren't dilated properly. Also three cases from group 1/9000 weren't dilated properly after intracameral epinephrine. Conclusion: Intracameral epinephrine even in higher concentrations is effective in papillary dilatation especially in cases with long duration and poorly dilated cases by usual topical mydriatics.

  4. The eye as a window to the listening brain: neural correlates of pupil size as a measure of cognitive listening load.

    Science.gov (United States)

    Zekveld, Adriana A; Heslenfeld, Dirk J; Johnsrude, Ingrid S; Versfeld, Niek J; Kramer, Sophia E

    2014-11-01

    An important aspect of hearing is the degree to which listeners have to deploy effort to understand speech. One promising measure of listening effort is task-evoked pupil dilation. Here, we use functional magnetic resonance imaging (fMRI) to identify the neural correlates of pupil dilation during comprehension of degraded spoken sentences in 17 normal-hearing listeners. Subjects listened to sentences degraded in three different ways: the target female speech was masked by fluctuating noise, by speech from a single male speaker, or the target speech was noise-vocoded. The degree of degradation was individually adapted such that 50% or 84% of the sentences were intelligible. Control conditions included clear speech in quiet, and silent trials. The peak pupil dilation was larger for the 50% compared to the 84% intelligibility condition, and largest for speech masked by the single-talker masker, followed by speech masked by fluctuating noise, and smallest for noise-vocoded speech. Activation in the bilateral superior temporal gyrus (STG) showed the same pattern, with most extensive activation for speech masked by the single-talker masker. Larger peak pupil dilation was associated with more activation in the bilateral STG, bilateral ventral and dorsal anterior cingulate cortex and several frontal brain areas. A subset of the temporal region sensitive to pupil dilation was also sensitive to speech intelligibility and degradation type. These results show that pupil dilation during speech perception in challenging conditions reflects both auditory and cognitive processes that are recruited to cope with degraded speech and the need to segregate target speech from interfering sounds.

  5. Pupil diameter reflects uncertainty in attentional selection during visual search

    Directory of Open Access Journals (Sweden)

    Joy J. Geng

    2015-08-01

    Full Text Available Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones & Cohen, 2005b; Yu & Dayan, 2005. In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time and performance accuracy (Experiments 1-2. Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes.

  6. Tests and standards for express-control of physical fitness and health of middle school age pupils

    Directory of Open Access Journals (Sweden)

    Bodnar I.R.

    2016-08-01

    Full Text Available Introduction: to day, physical fitness testing often causes negative emotions in pupils. It results in sharp loss of pupils’ wish to fulfill physical exercises in free time and worsens their health. Possibility to assess health level is an important motivation factor for pupils’ passing physical tests. Objective testing system will form positive motivation for physical exercises’ practicing and will facilitate increase of pupils’ motor functioning. It will also facilitate optimization of their physical condition, improvement of physical fitness and strengthening of health. Material: we tested physical fitness level and made diagnosis of pupils’ functional state (10-15 years’ age; n=85 with the help of tool methodic. We also used regressive analysis. Results: the system of tests and standards for express-control over physical fitness and health of middle school age pupils has been worked out and substantiated. The system of tests envisages fulfillment of 4 exercises: back pressing ups on bench during 20 seconds; throwing and catching of ball with two hands from wall during 30 seconds; side bending; torso rising from lying position into sitting during 30 seconds. Integral indicator of pupils’ physical fitness and health correlates with functional state of organism’s leading systems. We worked out 5 levels’ scale for express-control over physical fitness and health of middle school age pupils. The system stipulates calculation of integrative indicator with the help of regression equation by results of 4 test exercises and calculation of one index. Conclusions: The system of tests and standards permits the following: to divide pupils into relatively uniform groups even at the beginning of academic year for successful reasonable physical load. The system also permits to determine standard and find what shall be strived for by a pupil in order to achieve optimal physical fitness and somatic state; to motivate relatively weakly

  7. American Indian Students' Perceptions of Actual and Ideal Dormitory Aide Pupil Control Behavior, and Students' Attitudes Regarding Their Dormitory Aides.

    Science.gov (United States)

    Davis, Jim L.

    Two hundred and eleven American Indian students (106 males and 105 females) attending an off-reservation BIA elementary boarding school in a predominantly non-Indian community in the midwest were tested to examine the relationship between the congruence of students' perception of and preferences for dormitory aide pupil control behavior and…

  8. Decision-related pupil dilation reflects upcoming choice and individual bias.

    Science.gov (United States)

    de Gee, Jan Willem; Knapen, Tomas; Donner, Tobias H

    2014-02-04

    A number of studies have shown that pupil size increases transiently during effortful decisions. These decision-related changes in pupil size are mediated by central neuromodulatory systems, which also influence the internal state of brain regions engaged in decision making. It has been proposed that pupil-linked neuromodulatory systems are activated by the termination of decision processes, and, consequently, that these systems primarily affect the postdecisional brain state. Here, we present pupil results that run contrary to this proposal, suggesting an important intradecisional role. We measured pupil size while subjects formed protracted decisions about the presence or absence ("yes" vs. "no") of a visual contrast signal embedded in dynamic noise. Linear systems analysis revealed that the pupil was significantly driven by a sustained input throughout the course of the decision formation. This sustained component was larger than the transient component during the final choice (indicated by button press). The overall amplitude of pupil dilation during decision formation was bigger before yes than no choices, irrespective of the physical presence of the target signal. Remarkably, the magnitude of this pupil choice effect (yes > no) reflected the individual criterion: it was strongest in conservative subjects choosing yes against their bias. We conclude that the central neuromodulatory systems controlling pupil size are continuously engaged during decision formation in a way that reveals how the upcoming choice relates to the decision maker's attitude. Changes in brain state seem to interact with biased decision making in the face of uncertainty.

  9. Luminance and chromatic signals interact differently with melanopsin activation to control the pupil light response.

    Science.gov (United States)

    Barrionuevo, Pablo A; Cao, Dingcai

    2016-09-01

    Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin. These cells receive afferent inputs from rods and cones, which provide inputs to the postreceptoral visual pathways. It is unknown, however, how melanopsin activation is integrated with postreceptoral signals to control the pupillary light reflex. This study reports human flicker pupillary responses measured using stimuli generated with a five-primary photostimulator that selectively modulated melanopsin, rod, S-, M-, and L-cone excitations in isolation, or in combination to produce postreceptoral signals. We first analyzed the light adaptation behavior of melanopsin activation and rod and cones signals. Second, we determined how melanopsin is integrated with postreceptoral signals by testing with cone luminance, chromatic blue-yellow, and chromatic red-green stimuli that were processed by magnocellular (MC), koniocellular (KC), and parvocellular (PC) pathways, respectively. A combined rod and melanopsin response was also measured. The relative phase of the postreceptoral signals was varied with respect to the melanopsin phase. The results showed that light adaptation behavior for all conditions was weaker than typical Weber adaptation. Melanopsin activation combined linearly with luminance, S-cone, and rod inputs, suggesting the locus of integration with MC and KC signals was retinal. The melanopsin contribution to phasic pupil responses was lower than luminance contributions, but much higher than S-cone contributions. Chromatic red-green modulation interacted with melanopsin activation nonlinearly as described by a "winner-takes-all" process, suggesting the integration with PC signals might be mediated by a postretinal site.

  10. Appropriate Pupilness

    DEFF Research Database (Denmark)

    Kofoed, Jette

    2008-01-01

    The analytical focus in this article is on how social categories intersect in daily school life and how intersections intertwine with other empirically relevant categories such as normality, pupilness and (in)appropriatedness. The point of empirical departure is a daily ritual where teams...... for football are selected. The article opens up for a microanalysis of everyday practices at the margins and at the core of what this article terms `pupilness'. The concept of intersectionality is suggested as a useful analytical tool to understand the multiple activities of pupils in everyday school life...

  11. Maintaining the balance: teacher control and pupil disruption in the classroom

    Directory of Open Access Journals (Sweden)

    J. Mark Halstead

    2009-12-01

    Full Text Available A class of 8-9 year-old children in England was observed for several months in order to explore their experiences of everydayschooling and especially the way they themselves understand these experiences. The research focused particularly on the waythey experience and understand non-educational classroom activities like rituals and routines, classroom management andcontrol, rewards and punishments. It highlighted the differences between the perceptions of the children and those of adults.One finding was that in the primary classroom children are under constant surveillance and control by the teacher, and thatthey may respond in a variety of ways. Sometimes they apparently accept the teacher’s discipline and authority, but othertimes they appear to subvert the teacher’s regulations and order through minor distractions, disruptions, attention-seeking andtime-wasting activities. In the specific research described in this paper the focus of attention was on the informal learning thatgoes on in the hidden curriculum as a result of these classroom routines and subversions, especially in the domain of values andattitudes. A variety of research methods was used to gather data, including small group interviews, informal conversations andgroup activities as well as observation. Relevant adults were also interviewed, especially the class-teacher himself, but the mainfocus of the research was always on the children’s own perceptions. The findings, which are rich in their implications forteacher training, show that in the children’s subversion of the teacher’s authority there is a fine balance of power betweenthem and the teacher. Even more importantly, they indicate that the pupils are consciously reflecting on and learning fromtheir own behaviour and experiences and are thus taking the first steps towards becoming morally autonomous individuals

  12. Does pupil constriction under blue and green monochromatic light exposure change with age?

    Science.gov (United States)

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S; Doyon, Julien; Gronfier, Claude; Cooper, Howard M; Dumont, Marie; Carrier, Julie

    2012-06-01

    Many nonvisual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness, and gene expression decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4 years) and 14 older (61±4.4 years) healthy subjects during 45-second exposures to blue (480 nm) and green (550 nm) monochromatic lights at low (7×10(12) photons/cm2/s), medium (3×10(13) photons/cm2/s), and high (10(14) photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect nonvisual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to

  13. Does pupil constriction under blue and green monochromatic light exposure change with age?

    Science.gov (United States)

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S.; Doyon, Julien; Gronfier, Claude; Cooper, Howard M.; Dumont, Marie; Carrier, Julie

    2017-01-01

    Many non-visual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness and gene expression, decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4y) and 14 older (61±4.4y) healthy subjects during 45s exposures to blue (480nm) and green (550nm) monochromatic lights at low (7×1012 photons/cm2/s), medium (3×1013 photons/cm2/s), and high (1014 photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects, for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect non-visual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to remain relatively

  14. Teachers' and Pupils' Behavior in Large and Small Classes: A Systematic Observation Study of Pupils Aged 10 and 11 Years

    Science.gov (United States)

    Blatchford, Peter; Bassett, Paul; Brown, Penelope

    2005-01-01

    The authors examined class size effects on teacher-pupil interactions, pupil engagement, and pupil-pupil interaction. They extended previous research by recognizing the hierarchical nature of observation data and the possible influence of other variables. The study used a time sampling method involving 257 children (aged 10-11 years) in 16 small…

  15. 驾车接近隧道过程中驾驶员瞳孔大小变化规律%Changing rule of drivers’pupil size as driving into tunnels

    Institute of Scientific and Technical Information of China (English)

    胡英奎; 陈仲林; 张青文; 翁季; 黄珂

    2015-01-01

    为了解驾驶员驾车进入隧道过程中的瞳孔变化过程,让8位驾驶员分别驾车进入4座隧道,在此过程中用眼动仪记录驾驶员的瞳孔大小。分析眼动仪记录得到的驾驶员瞳孔大小数据的特征,通过小波变换进行数据处理,得到了驾驶员驾车进入隧道过程中瞳孔大小变化曲线。分析驾驶员瞳孔大小变化曲线发现,不同驾驶员的瞳孔大小存在个体差异;同一驾驶员多次测试的瞳孔大小存在一定的随机性;在接近隧道过程中驾驶员瞳孔逐渐变大,并在隧道洞口附近急剧变大;不同驾驶员的瞳孔变化趋势存在一定的差异;驾驶员瞳孔大小除受适应亮度的影响外,还受驾驶员的心理等因素的影响。%To reveal the changing process of drivers’pupil size during driving were carried out into of tunnels, experiments eight drivers drived into four tunnels at different time.And their pupil size were recorded with eye tracker in the driving process.The recorded raw data by eye tracker was analyzed,wavelet transforms method was taken to process the data,and the pupil size changing curves of drivers when they drive into tunnels.From the curves analysis,it has been found that the individual difference exist on different drivers’pupil size;There was a degree of randomness of pupil sizes amone repeated test of the same driver;the drivers’pupil enlarged gradually when they driving into tunnels,and enlarged violently nearby tunnel’s threshold;the pupil size changing tendency of different driver exists some difference;drivers’pupil size was influence not only by adaptation luminance,but also by their psychological factors.

  16. Dynamic exit pupil trackers for autostereoscopic displays.

    Science.gov (United States)

    Akşit, Kaan; Baghsiahi, Hadi; Surman, Phil; Ölçer, Selim; Willman, Eero; Selviah, David R; Day, Sally; Urey, Hakan

    2013-06-17

    This paper describes the first demonstrations of two dynamic exit pupil (DEP) tracker techniques for autostereoscopic displays. The first DEP tracker forms an exit pupil pair for a single viewer in a defined space with low intraocular crosstalk using a pair of moving shutter glasses located within the optical system. A display prototype using the first DEP tracker is constructed from a pair of laser projectors, pupil-forming optics, moving shutter glasses at an intermediate pupil plane, an image relay lens, and a Gabor superlens based viewing screen. The left and right eye images are presented time-sequentially to a single viewer and seen as a 3D image without wearing glasses and allows the viewer to move within a region of 40 cm × 20 cm in the lateral plane, and 30 cm along the axial axis. The second DEP optics can move the exit pupil location dynamically in a much larger 3D space by using a custom spatial light modulator (SLM) forming an array of shutters. Simultaneous control of multiple exit pupils in both lateral and axial axes is demonstrated for the first time and provides a viewing volume with an axial extent of 0.6-3 m from the screen and within a lateral viewing angle of ± 20° for multiple viewers. This system has acceptable crosstalk (< 5%) between the stereo image pairs. In this novel version of the display the optical system is used as an advanced dynamic backlight for a liquid crystal display (LCD). This has advantages in terms of overall display size as there is no requirement for an intermediate image, and in image quality. This system has acceptable crosstalk (< 5%) between the stereo image pairs.

  17. The Effects of Large Class Size on Effective EFL Teaching and Learning--A Study of Grade 10 Teachers and Pupils at "Instituto Médio Politécnico do Namibe?

    Science.gov (United States)

    Sangangula, Londaka Amasio

    2016-01-01

    The purpose of this study was to provide views of teachers and pupils on large class size and its effects on teaching and English learning, at "Instituto Médio Politécnico do Namibe", and by showing that the large class scenario at IMP-Namibe may be attributed to various factors of which the most pertinent is the imbalance between the…

  18. Fuzzy Mathematics for Raw Silk Size Control

    Institute of Scientific and Technical Information of China (English)

    HU Zheng-yu; YU Hai-feng; GU Ping

    2008-01-01

    With photographing and experiments,this paper divides the cocoon layers into three categories according to their colors,establishes three-color membership function based on fuzzy mathemtics,constructs fuzzy sets which satisfy the range of size contrd by using the ordinary set and attached fiequency of three color cocoons combination,then achieves the ordinary sets of range of size control by choosing λ-cut.Under these ordinary sets,each end does duality relative level,then sets up relative matrix and overall sequence and finds the membership function to iudge whether the size cmtrol is normal.

  19. Large pupils predict goal-driven eye movements.

    Science.gov (United States)

    Mathôt, Sebastiaan; Siebold, Alisha; Donk, Mieke; Vitu, Françoise

    2015-06-01

    Here we report that large pupils predict fixations of the eye on low-salient, inconspicuous parts of a visual scene. We interpret this as showing that mental effort, reflected by a dilation of the pupil, is required to guide gaze toward objects that are relevant to current goals, but that may not be very salient. When mental effort is low, reflected by a constriction of the pupil, the eyes tend to be captured by high-salient parts of the image, irrespective of top-down goals. The relationship between pupil size and visual saliency was not driven by luminance or a range of other factors that we considered. Crucially, the relationship was strongest when mental effort was invested exclusively in eye-movement control (i.e., reduced in a dual-task setting), which suggests that it is not due to general effort or arousal. Our finding illustrates that goal-driven control during scene viewing requires mental effort, and that pupil size can be used as an online measure to track the goal-drivenness of behavior. (c) 2015 APA, all rights reserved).

  20. Control of pore size in epoxy systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patricia Sue; Lenhart, Joseph Ludlow (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Kallam, Alekhya (North Dakota State University, Fargo, ND); Majumdar, Partha (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J. (North Dakota State University, Fargo, ND); Celina, Mathias Christopher; Bahr, James (North Dakota State University, Fargo, ND); Klein, Robert J.

    2009-01-01

    Both conventional and combinatorial approaches were used to study the pore formation process in epoxy based polymer systems. Sandia National Laboratories conducted the initial work and collaborated with North Dakota State University (NDSU) using a combinatorial research approach to produce a library of novel monomers and crosslinkers capable of forming porous polymers. The library was screened to determine the physical factors that control porosity, such as porogen loading, polymer-porogen interactions, and polymer crosslink density. We have identified the physical and chemical factors that control the average porosity, pore size, and pore size distribution within epoxy based systems.

  1. [Pupil and melanopsin photoreception].

    Science.gov (United States)

    Ishikawa, Hitoshi

    2013-03-01

    photoreceptor cells, and to evaluate the relative contribution of pupil light response using the control, instigated pharmacological blockade of neurotransmission (PB) model and a transgenic model of retinal degeneration (Tg) rabbit. Although rod and cone photoreceptors disappeared in the PB and Tg models, miosis was still induced during exposure to blue light (470 nm). The greater sustained constriction of pupils to blue light in eyes with outer retinal damage reflects mRGC activation. Our study also indicated that some histologically-identified RGCs were consistent with the characteristics and structures of mRGC. Clinically, in age-related macular degeneration patients, there was no reliable recordable pupil response to red light, even at the brightest intensity but a blue light evoked a sustained pupil constriction. However, in glaucoma patients, there was no reliable recordable pupil response to the brightest intensity of blue light. These preliminary recordings in human subjects demonstrate that changes in the pupil responses to chromatic stimuli are readily detectable and easily quantifiable with standard instruments of clinical testing. We hypothesize that changes in the transient pupil response to red light and low intensity blue light may be more sensitive to cone and rod disease, whereas changes in the sustained pupil response to bright blue light may be more sensitive to optic nerve disease. Ongoing studies of the pupil are aimed at optimizing stimulus conditions that elicit pupil responses that can better localize the site of damage to rods, cones, and RGCs, to quantify the extent of disease.

  2. Advanced Attitude Control af Pico Sized Satellites

    DEFF Research Database (Denmark)

    Larsen, Jesper A.; Amini, Rouzbeh; Izadi-Zamanabadi, Roozbeh

    2005-01-01

    accuracy of better than 5 degrees. Cost, size, weight and power requirements, on the other hand, impose selecting relative simple sensors and actuators which leads to an attitude control requirement of less than 1 degree. This precision is obtained by a combination of magnetorquers and momentum wheels...

  3. Cognitive and Ocular Factors Jointly Determine Pupil Responses under Equiluminance.

    Directory of Open Access Journals (Sweden)

    Tomas Knapen

    Full Text Available Changes in pupil diameter can reflect high-level cognitive signals that depend on central neuromodulatory mechanisms. However, brain mechanisms that adjust pupil size are also exquisitely sensitive to changes in luminance and other events that would be considered a nuisance in cognitive experiments recording pupil size. We implemented a simple auditory experiment involving no changes in visual stimulation. Using finite impulse-response fitting we found pupil responses triggered by different types of events. Among these are pupil responses to auditory events and associated surprise: cognitive effects. However, these cognitive responses were overshadowed by pupil responses associated with blinks and eye movements, both inevitable nuisance factors that lead to changes in effective luminance. Of note, these latter pupil responses were not recording artifacts caused by blinks and eye movements, but endogenous pupil responses that occurred in the wake of these events. Furthermore, we identified slow (tonic changes in pupil size that differentially influenced faster (phasic pupil responses. Fitting all pupil responses using gamma functions, we provide accurate characterisations of cognitive and non-cognitive response shapes, and quantify each response's dependence on tonic pupil size. These results allow us to create a set of recommendations for pupil size analysis in cognitive neuroscience, which we have implemented in freely available software.

  4. Comparison of availability and offer of controlled physical activities for pupils with disability in selected regions of Czech Republic and United Kingdom

    Directory of Open Access Journals (Sweden)

    Zuzana Kornatovská

    2016-11-01

    Full Text Available Background: The European Union and other countries of the world need quality research data, without which it cannot assess how the overall situation of persons with disabilities develops. Objective: The aim of this paper is to compare the availability of controlled physical activities for pupils with mental disabilities, hearing or visual disabilities in selected regions of the Czech Republic and Great Britain (region of South Bohemia and the region West Midlands. Partial aim is to analyse an offer of the controlled physical activities for this population of pupils. Methods: We used analytical investigative methods (Investigative pentagram. The survey was based on explanation, exploration and direct observation. Another method was a tool "ArcGIS" evaluating the distance of polygons and "packaging zones" by driving times for the EU - Index of availability. After that it was determined the availability of controlled physical activities for pupils with the observed types of disability and evaluated the hypothesis H1. In surveyed regions were also examined ways of organizing a range of offers of controlled physical activities for pupils with disabilities. Results: The range of controlled physical activities was verified higher in the West Midlands region compared to the South Bohemian region. It was found that the British region unlike the South Bohemian region accentuated non-confrontational character of the controlled physical activities with health preventive impact (yoga, swimming and social integration (dancing, walking and hiking. Conclusions: It was verified the hypothesis H1, assuming that the availability of controlled physical activities for pupils with mental disabilities, hearing, visual is significantly higher in the surveyed region of the UK compared to the surveyed region in the Czech Republic.

  5. The Effects of Parental Involvement, Trust in Parents, Trust in Students and Pupil Control Ideology on Conflict Management Strategies of Early Childhood Teachers

    Science.gov (United States)

    Karakus, Mehmet; Savas, Ahmet Cezmi

    2012-01-01

    In this study it was aimed to determine the effects of parental involvement, teachers' trust in parents and students, and teachers' pupil control ideology on the conflict management strategies used by teachers in classroom management. Data were collected from a sample of 254 teachers through paper and pencil questionnaires. Data were analyzed with…

  6. Neural Correlates of Fast Pupil Dilation in Nonhuman Primates: Relation to Behavioral Performance and Cognitive Workload

    Science.gov (United States)

    Hampson, R.E.; Opris, Ioan; Deadwyler, S.A.

    2010-01-01

    Pupil dilation in humans has been previously shown to correlate with cognitive workload, whereby increased frequency of dilation is associated with increased degree of difficulty of a task. It has been suggested that frontal oculomotor brain areas control cognitively-related pupil dilations, but this has not been confirmed due to lack of animal models of cognitive workload and task-related pupil dilation. This is the first report of a wavelet analysis applied to continuous measures of pupil size used to detect the onset of abrupt pupil dilations and the frequency of those dilations in nonhuman primates (NHPs) performing a trial-unique delayed match to sample (DMS) task. An additional unique finding shows that electrophysiological recordings in the same animals revealed correlated firing of neurons in frontal cortex with different components of pupil dilation during task performance. It is further demonstrated that the frequency of fast pupil dilations (but not rate of eye movements) correlated with cognitive workload during task performance. Such correlations suggest that frontal neuron encoding of pupil dilation provides critical feedback to other brain areas involved in the processing of complex visual information. PMID:20226215

  7. Effectiveness of semantic therapy for word-finding difficulties in pupils with persistent language impairments: a randomized control trial.

    Science.gov (United States)

    Ebbels, Susan H; Nicoll, Hilary; Clark, Becky; Eachus, Beth; Gallagher, Aoife L; Horniman, Karen; Jennings, Mary; McEvoy, Kate; Nimmo, Liz; Turner, Gail

    2012-01-01

    Word-finding difficulties (WFDs) in children have been hypothesized to be caused at least partly by poor semantic knowledge. Therefore, improving semantic knowledge should decrease word-finding errors. Previous studies of semantic therapy for WFDs are inconclusive. To investigate the effectiveness of semantic therapy for secondary school-aged pupils with WFDs using a randomized control trial with blind assessment. Fifteen participants with language impairments and WFDs (aged 9;11-15;11) were randomly assigned to a therapy versus waiting control group. In Phase 1 the therapy group received two 15-min semantic therapy sessions per week for 8 weeks with their usual speech and language therapist. Therapy for each participant targeted words from one of three semantic categories (animals, food, clothes). All participants were tested pre- and post-phase 1 therapy on the brief version of the Test of Adolescent Word Finding (TAWF), semantic fluency and the Test of Word Finding in Discourse (TWFD). In Phase 2 the waiting control group received the same therapy as the original therapy group, which received therapy targeted at other language areas. Testing after Phase 2 aimed to establish whether the waiting control group made similar progress to the original therapy group and whether the original therapy group maintained any gains. The original therapy group made significant progress in standard scores on the TAWF (d= 0.94), which was maintained 5 months later. However, they made no progress on the semantic fluency or discourse tests. Participants in the waiting control group did not make significant progress on the TAWF in Phase 1 when they received no word-finding therapy. However, after Phase 2, when they received the therapy, they also made significant progress (d= 0.81). The combined effect of therapy over the two groups was d= 1.2. The mean standard scores on the TAWF were 67 pre-therapy and 77 post-therapy. Four hours of semantic therapy on discrete semantic categories

  8. Global Climatic Controls On Leaf Size

    Science.gov (United States)

    Wright, I. J.; Prentice, I. C.; Dong, N.; Maire, V.

    2015-12-01

    Since the 1890s it's been known that the wet tropics harbour plants with exceptionally large leaves. Yet the observed latitudinal gradient of leaf size has never been fully explained: it is still unclear which aspects of climate are most important for understanding geographic trends in leaf size, a trait that varies many thousand-fold among species. The key is the leaf-to-air temperature difference, which depends on the balance of energy inputs (irradiance) and outputs (transpirational cooling, losses to the night sky). Smaller leaves track air temperatures more closely than larger leaves. Widely cited optimality-based theories predict an advantage for smaller leaves in dry environments, where transpiration is restricted, but are silent on the latitudinal gradient. We aimed to characterize and explain the worldwide pattern of leaf size. Across 7900 species from 651 sites, here we show that: large-leaved species predominate in wet, hot, sunny environments; smaller-leaved species typify hot, sunny environments only when arid; small leaves are required to avoid freezing in high latitudes and at high elevation, and to avoid overheating in dry environments. This simple pattern was unclear in earlier, more limited analyses. We present a simple but robust, fresh approach to energy-balance modelling for both day-time and night-time leaf-to-air temperature differences, and thus risk of overheating and of frost damage. Our analysis shows night-chilling is important as well as day-heating, and simplifies leaf temperature modelling. It provides both a framework for modelling leaf size constraints, and a solution to one of the oldest conundrums in ecology. Although the path forward is not yet fully clear, because of its role in controlling leaf temperatures we suggest that climate-related leaf size constraints could usefully feature in the next generation of land ecosystem models.

  9. Pupil responses to task requirement in goal-directed movements

    OpenAIRE

    Jiang, Xianta

    2014-01-01

    Objectively measuring the operators’ task workload in goal-directed motor tasks such as surgical operations, is important for performance and safety. This thesis presents an approach for objectively measuring task workload in goal-directed movements using an important eye response: the pupil diameter. We demonstrate how to capture movement-related pupil size changes during motor tasks, investigate how the pupil responds to task requirement, and show that the pupil diameter can be employed a...

  10. Investigation of Nonlinear Pupil Dynamics by Recurrence Quantification Analysis

    Directory of Open Access Journals (Sweden)

    L. Mesin

    2013-01-01

    Full Text Available Pupil is controlled by the autonomous nervous system (ANS. It shows complex movements and changes of size even in conditions of constant stimulation. The possibility of extracting information on ANS by processing data recorded during a short experiment using a low cost system for pupil investigation is studied. Moreover, the significance of nonlinear information contained in the pupillogram is investigated. We examined 13 healthy subjects in different stationary conditions, considering habitual dental occlusion (HDO as a weak stimulation of the ANS with respect to the maintenance of the rest position (RP of the jaw. Images of pupil captured by infrared cameras were processed to estimate position and size on each frame. From such time series, we extracted linear indexes (e.g., average size, average displacement, and spectral parameters and nonlinear information using recurrence quantification analysis (RQA. Data were classified using multilayer perceptrons and support vector machines trained using different sets of input indexes: the best performance in classification was obtained including nonlinear indexes in the input features. These results indicate that RQA nonlinear indexes provide additional information on pupil dynamics with respect to linear descriptors, allowing the discrimination of even a slight stimulation of the ANS. Their use in the investigation of pathology is suggested.

  11. Controls of eolian dune size and spacing

    Science.gov (United States)

    Lancaster, N.

    1988-11-01

    Data for the Namib and Gran Desierto sand seas suggest that the controls of dune size and spacing are complex. The relation between dune height and spacing varies with dune type and location and reflects both dune dynamics (vertical accretion vs. migration or extension) and availability of sand. There is no general relation between dune spacing and grain size. In the Namib sand sea the height of compound and complex dunes (draas) is inversely proportional to potential sand-transport rates, whereas the height of dunes superimposed on their flanks varies directly with potential sand-transport rates. These observations can be combined with data on dune spacing to demonstrate the existence of a hierarchy of eolian dunes, each element of which responds to variations in sand-transport rates at different temporal and spatial scales. Whereas the morphology of individual simple dunes and superimposed dunes on draas is related to contemporary rates and directions of sand transport, the morphology and development of draas reflects long-term and regional patterns of sand transport and deposition.

  12. EPICS Controlled Collimator for Controlling Beam Sizes in HIPPO

    Energy Technology Data Exchange (ETDEWEB)

    Napolitano, Arthur Soriano [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Controlling the beam spot size and shape in a diffraction experiment determines the probed sample volume. The HIPPO - High-Pressure-Preferred Orientation– neutron time-offlight diffractometer is located at the Lujan Neutron Scattering Center in Los Alamos National Laboratories. HIPPO characterizes microstructural parameters, such as phase composition, strains, grain size, or texture, of bulk (cm-sized) samples. In the current setup, the beam spot has a 10 mm diameter. Using a collimator, consisting of two pairs of neutron absorbing boron-nitride slabs, horizontal and vertical dimensions of a rectangular beam spot can be defined. Using the HIPPO robotic sample changer for sample motion, the collimator would enable scanning of e.g. cylindrical samples along the cylinder axis by probing slices of such samples. The project presented here describes implementation of such a collimator, in particular the motion control software. We utilized the EPICS (Experimental Physics Interface and Control System) software interface to integrate the collimator control into the HIPPO instrument control system. Using EPICS, commands are sent to commercial stepper motors that move the beam windows.

  13. Control of transcription by cell size.

    Directory of Open Access Journals (Sweden)

    Chia-Yung Wu

    Full Text Available Cell size increases significantly with increasing ploidy. Differences in cell size and ploidy are associated with alterations in gene expression, although no direct connection has been made between cell size and transcription. Here we show that ploidy-associated changes in gene expression reflect transcriptional adjustment to a larger cell size, implicating cellular geometry as a key parameter in gene regulation. Using RNA-seq, we identified genes whose expression was altered in a tetraploid as compared with the isogenic haploid. A significant fraction of these genes encode cell surface proteins, suggesting an effect of the enlarged cell size on the differential regulation of these genes. To test this hypothesis, we examined expression of these genes in haploid mutants that also produce enlarged size. Surprisingly, many genes differentially regulated in the tetraploid are identically regulated in the enlarged haploids, and the magnitude of change in gene expression correlates with the degree of size enlargement. These results indicate a causal relationship between cell size and transcription, with a size-sensing mechanism that alters transcription in response to size. The genes responding to cell size are enriched for those regulated by two mitogen-activated protein kinase pathways, and components in those pathways were found to mediate size-dependent gene regulation. Transcriptional adjustment to enlarged cell size could underlie other cellular changes associated with polyploidy. The causal relationship between cell size and transcription suggests that cell size homeostasis serves a regulatory role in transcriptome maintenance.

  14. How pupils percieve the teacher's motivational techniques?

    Directory of Open Access Journals (Sweden)

    Bodroža Bojana

    2015-01-01

    Full Text Available Current research in the field of education indicates that the behaviour of the teacher affects significantly the quality and level of the pupil's motivation. The aim of our research was to determine the structure of the motivational style of teachers seen from the pupils' perspective, and to find out whether the pupils' perceptions of the teacher's motivational style depend upon cultural-educational influences of the family, and some characteristics of the students (academic achievements, gender. The sample included 856 pupils from 40 elementary schools in Serbia. We used the questionnaire with Likert's scale to obtain the evaluation of the teachers' behaviours. By the factor analysis we extracted three components of the teacher' behaviour: stimulating pupils' interest and competences, de-motivational teachers' behaviours and stimulating freedom of thinking and expression. The results show that the pupils whose parents have lower levels of education think that the behaviour of the teachers is directed to stimulating interest and competencies, as well as freedom of thinking and speech than the pupils of the parents of higher educational status. The control of the influence of the education of parents showed that the pupils of lower academic achievement perceive the teacher's behaviour as de-motivational. Compared to girls boys estimate more highly that teachers stimulate their interests and competencies. A suggestion is offered how a teacher should develop a behavioural style which would positively influence the quality of the pupils' motivation.

  15. Pupil responses derived from outer and inner retinal photoreception are normal in patients with hereditary optic neuropathy.

    Science.gov (United States)

    Kawasaki, Aki; Collomb, Sylvie; Léon, Lorette; Münch, Mirjam

    2014-03-01

    We compared the pupil responses originating from outer versus inner retinal photoreception between patients with isolated hereditary optic neuropathy (HON, n = 8) and healthy controls (n = 8). Three different testing protocols were used. For the first two protocols, a response function of the maximal pupil contraction versus stimulus light intensity was generated and the intensity at which half of the maximal pupil contraction, the half-max intensity, was determined. For the third protocol, the pupil size after light offset, the re-dilation rate and re-dilation amplitude were calculated to assess the post-light stimulus response. Patients with HON had bilateral, symmetric optic atrophy and significant reduction of visual acuity and visual field compared to controls. There were no significant mean differences in the response curve and pupil response parameters that reflect mainly rod, cone or melanopsin activity between patients and controls. In patients, there was a significant correlation between the half-max intensity of the red light sequence and visual field loss. In conclusion, pupil responses derived from outer or inner retinal photoreception in HON patients having mild-to moderate visual dysfunction are not quantitatively different from age-matched controls. However, an association between the degree of visual field loss and the half-max intensity of the cone response suggests that more advanced stages of disease may lead to impaired pupil light reflexes.

  16. Environmental controls on alpine cirque size

    Science.gov (United States)

    Delmas, Magali; Gunnell, Yanni; Calvet, Marc

    2014-02-01

    Pleistocene alpine cirques are emblematic landforms of mountain scenery, yet their deceptively simple template conceals complex controlling variables. This comparative study presents a new database of 1071 cirques, the largest of its kind, located in the French eastern Pyrenees. It is embedded in a review of previous work on cirque morphometry and thus provides a perspective on a global scale. First-order cirque attributes of length, width, and amplitude were measured; and their power as predictors of climatic and lithological variables and as proxies for the duration of glacier activity was tested using ANOVA, simple and multiple linear regression, and their various post-hoc tests. Conventional variables such as cirque aspect, floor elevation, and exposure with respect to regional precipitation-bearing weather systems are shown to present some consistency in spatial patterns determined by solar radiation, the morning-afternoon effect, and wind-blown snow accumulation in the lee of ridgetops. This confirms in greater detail the previously encountered links between landforms and climate. A special focus on the influence of bedrock lithology, a previously neglected nonclimatic variable, highlights the potential for spurious relations in the use of cirque size as a proxy of past environmental conditions. Cirques are showcased as complex landforms resulting from the combination of many climatic and nonclimatic variables that remain difficult to rank by order of importance. Apart from a few statistically weak trends, several combinations of different factors in different proportions are shown to produce similar morphometric outcomes, suggesting a case of equifinality in landform development.

  17. Modulation of stimulus contrast on the human pupil orienting response.

    Science.gov (United States)

    Wang, Chin-An; Munoz, Douglas P

    2014-09-01

    The sudden appearance of a novel stimulus initiates a series of responses to orient the body for appropriate actions, including not only shifts of gaze and attention, but also transient pupil dilation. Modulation of pupil dynamics by stimulus properties is less understood, although its effects on other components of orienting have been extensively explored. Microstimulation of the superior colliculus evoked transient pupil dilation, and the initial component of pupil dilation evoked by microstimulation was similar to that elicited by the presentation of salient sensory stimuli, suggesting a coordinated role of the superior colliculus on this behavior, although evidence in humans is yet to be established. To examine pupil orienting responses in humans, we presented visual stimuli while participants fixated on a central visual spot. Transient pupil dilation in humans was elicited after presentation of a visual stimulus in the periphery. The evoked pupil responses were modulated systematically by stimulus contrast, with faster and larger pupil responses triggered by higher contrast stimuli. The pupil response onset latencies for high contrast stimuli were similar to those produced by the light reflex and significantly faster than the darkness reflex, suggesting that the initial component of pupil dilation is probably mediated by inhibition of the parasympathetic pathway. The contrast modulation was pronounced under different levels of baseline pupil size. Together, our results demonstrate visual contrast modulation on the orienting pupil response in humans.

  18. Music chills: The eye pupil as a mirror to music's soul.

    Science.gov (United States)

    Laeng, Bruno; Eidet, Lise Mette; Sulutvedt, Unni; Panksepp, Jaak

    2016-08-01

    This study evaluated whether music-induced aesthetic "chill" responses, which typically correspond to peak emotional experiences, can be objectively monitored by degree of pupillary dilation. Participants listened to self-chosen songs versus control songs chosen by other participants. The experiment included an active condition where participants made key presses to indicate when experiencing chills and a passive condition (without key presses). Chills were reported more frequently for self-selected songs than control songs. Pupil diameter was concurrently measured by an eye-tracker while participants listened to each of the songs. Pupil size was larger within specific time-windows around the chill events, as monitored by key responses, than in comparison to pupil size observed during 'passive' song listening. In addition, there was a clear relationship between pupil diameter within the chills-related time-windows during both active and passive conditions, thus ruling out the possibility that chills-related pupil dilations were an artifact of making a manual response. These findings strongly suggest that music chills can be visible in the moment-to-moment changes in the size of pupillary responses and that a neuromodulatory role of the central norepinephrine system is thereby implicated in this phenomenon.

  19. Adaptive instruction and pupil achievement

    NARCIS (Netherlands)

    Houtveen, A.A M; Booy, N; de Jong, Robert (Rob); van de Grift, W.J C M

    1999-01-01

    In this article the results are reported of a quasi-experiment on effects of adaptive instruction on reading results of children in the first year of reading instruction in Dutch primary schools. The research involved 456 pupils from 23 schools (12 experimental and 11 control group schools). Teacher

  20. Tonic Pupil Following Traumatic Hyphema: Case Report

    Directory of Open Access Journals (Sweden)

    Şaban Gönül

    2013-04-01

    Full Text Available A 7-year-old girl was admitted to our clinic after crash injury with air gun pellet in her right eye. There was an intense anterior chamber reaction and hyphema on the biomicroscopic examination. During the control examination after treatment of hyphema including cyclopentolate 1%, prednisolone acetate 1% and lomefloxacin 0.3%, anisocoria and mydriasis in the right eye were observed and the difference between both pupils was less in darkness. The case was diagnosed as tonic pupil following trauma, and diluted pilocarpine 0.125% test was performed. On diluted pilocarpine test, right pupil responded excessively to pilocarpine compared with the other pupil. As in our case, in cases with anisocoria following blunt trauma to orbit, tonic pupil should be keep in mind. (Turk J Ophthalmol 2013; 43: 132-4

  1. Detection of Changes in Surgical Difficulty: Evidence From Pupil Responses.

    Science.gov (United States)

    Zheng, Bin; Jiang, Xianta; Atkins, M Stella

    2015-12-01

    Assessing the workload of surgeons requires technology to continuously monitor surgeons' behaviors without interfering with their performance. We investigated the feasibility of using eye-tracking to reveal surgeons' response to increasing task difficulty. A controlled study was conducted in a simulated operating room, where 14 subjects were required to perform a laparoscopic procedure that includes 9 subtasks. The subtasks could be divided into 3 types with different levels of task difficulty, calculated by the index of task difficulty (ID) proposed by Fitts in 1954. Pupillary responses of subjects in performing the procedure were recorded using Tobii eye-tracking equipment. Peak pupil dilation and movement time were compared between subtasks with different IDs as well as between fast moving and slow aiming phases within each subtask. When the task difficulty was increased, task completion time increased. Meanwhile, the subjects' peak pupil size also increased. As the entire procedure was performed continuously, we found that pupil responses were not only affected by the ID in the current subtask but also influenced by subtasks before and after. Decomposing a surgical procedure into meaningful subtasks and examining the surgeon's pupil response to each subtask enables us to identify the challenging steps within a continuous surgical procedure. Psychomotor evidence on surgeon's performance may lead to an innovation for designing a task-specific training curriculum. © The Author(s) 2015.

  2. The Pupil Premium: Next Steps

    Science.gov (United States)

    Sutton Trust, 2015

    2015-01-01

    The pupil premium was introduced by the Coalition government in April 2011 to provide additional funding for disadvantaged pupils. The main difference between the premium and previous funding for disadvantaged pupils is that the premium is linked to individual pupils. On July 1, 2015, The Pupil Premium Summit organized by the Education Endowment…

  3. Green synthesis of size controllable gold nanoparticles

    Science.gov (United States)

    Mohan Kumar, Kesarla; Mandal, Badal Kumar; Kiran Kumar, Hoskote A.; Maddinedi, Sireesh Babu

    2013-12-01

    A facile rapid green eco-friendly method to synthesize gold nanoparticles (Au NPs) of tunable size using aqueous Terminalia arjuna fruit extracts has been demonstrated herein. Formation of Au NPs was confirmed by Surface Plasmon Resonance (SPR) study at 528 nm using UV-visible spectrophotometer. The time of reduction, size and morphological variations of Au NPs were studied with varying quantities of T. arjuna fruit aqueous extracts. Synthesized Au NPs were characterized using UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDAX). Polyphenols responsible for reduction of Au3+ to Au0 were identified using High Performance Liquid Chromatography (HPLC) as ascorbic acid, gallic acid and pyrogallol. The oxidized forms of polyphenols formed coordination with surface of Au NPs which protected their further growth and aggregation. We also propose a plausible mechanism how to tune size and shape of Au NPs by varying the quantity of extracts. Thus obtained Au NPs were stable for more than four months.

  4. Green synthesis of size controllable gold nanoparticles.

    Science.gov (United States)

    Mohan Kumar, Kesarla; Mandal, Badal Kumar; Kiran Kumar, Hoskote A; Maddinedi, Sireesh Babu

    2013-12-01

    A facile rapid green eco-friendly method to synthesize gold nanoparticles (Au NPs) of tunable size using aqueous Terminalia arjuna fruit extracts has been demonstrated herein. Formation of Au NPs was confirmed by Surface Plasmon Resonance (SPR) study at 528 nm using UV-visible spectrophotometer. The time of reduction, size and morphological variations of Au NPs were studied with varying quantities of T. arjuna fruit aqueous extracts. Synthesized Au NPs were characterized using UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDAX). Polyphenols responsible for reduction of Au(3+) to Au(0) were identified using High Performance Liquid Chromatography (HPLC) as ascorbic acid, gallic acid and pyrogallol. The oxidized forms of polyphenols formed coordination with surface of Au NPs which protected their further growth and aggregation. We also propose a plausible mechanism how to tune size and shape of Au NPs by varying the quantity of extracts. Thus obtained Au NPs were stable for more than four months.

  5. Assessing Visual Delays using Pupil Oscillations

    Science.gov (United States)

    Mulligan, Jeffrey B.

    2012-01-01

    Stark (1962) demonstrated vigorous pupil oscillations by illuminating the retina with a beam of light focussed to a small spot near the edge of the pupil. Small constrictions of the pupil then are sufficient to completely block the beam, amplifying the normal relationship between pupil area and retinal illuminance. In addition to this simple and elegant method, Stark also investigated more complex feedback systems using an electronic "clamping box" which provided arbitrary gain and phase delay between a measurement of pupil area and an electronically controlled light source. We have replicated Stark's results using a video-based pupillometer to control the luminance of a display monitor. Pupil oscillations were induced by imposing a linear relationship between pupil area and display luminance, with a variable delay. Slopes of the period-vs-delay function for 3 subjects are close to the predicted value of 2 (1.96-2.39), and the implied delays range from 254 to 376 508 to 652 milliseconds. Our setup allows us to extend Stark's work by investigating a broader class of stimuli.

  6. Transient pupil response is modulated by contrast-based saliency.

    Science.gov (United States)

    Wang, Chin-An; Boehnke, Susan E; Itti, Laurent; Munoz, Douglas P

    2014-01-08

    The sudden appearance of a novel stimulus in the environment initiates a series of orienting responses that include coordinated shifts of gaze and attention, and also transient changes in pupil size. Although numerous studies have identified a significant effect of stimulus saliency on shifts of gaze and attention, saliency effects on pupil size are less understood. To examine salience-evoked pupil responses, we presented visual, auditory, or audiovisual stimuli while monkeys fixated a central visual spot. Transient pupil dilation was elicited after visual stimulus presentation regardless of target luminance relative to background, and auditory stimuli also evoked similar pupil responses. Importantly, the evoked pupil response was modulated by contrast-based saliency, with faster and larger pupil responses following the presentation of more salient stimuli. The initial transient component of pupil dilation was qualitatively similar to that evoked by weak microstimulation of the midbrain superior colliculus. The pupil responses elicited by audiovisual stimuli were well predicted by a linear summation of each modality response. Together, the results suggest that the transient pupil response, as one component of orienting, is modulated by contrast-based saliency, and the superior colliculus is likely involved in its coordination.

  7. Molecular mechanism of size control in development and human diseases

    Institute of Scientific and Technical Information of China (English)

    Xiaolong Yang; Tian Xu

    2011-01-01

    How multicellular organisms control their size is a fundamental question that fascinated generations of biologists.In the past 10 years, tremendous progress has been made toward our understanding of the molecular mechanism underlying size control. Original studies from Drosophila showed that in addition to extrinsic nutritional and hormonal cues, intrinsic mechanisms also play important roles in the control of organ size during development. Several novel signaling pathways such as insulin and Hippo-LATS signaling pathways have been identified that control organ size by regulating cell size and/or cell number through modulation of cell growth, cell division, and cell death. Later studies using mammalian cell and mouse models also demonstrated that the signaling pathways identified in flies are also conserved in mammals. Significantly, recent studies showed that dysregulation of size control plays important roles in the development of many human diseases sucha as cancer,diabetes,and hypertrophy.

  8. Turn Up the Volume: Uncovering Nucleus Size Control Mechanisms.

    Science.gov (United States)

    Good, Matthew C

    2015-06-08

    Reporting in Developmental Cell, Hara and Merten (2015) apply the use of microfabrication and in vitro analysis in cell-free extracts to the old problem of nuclear size control. The authors make insights into the regulation of nuclear growth that potentially explain the widely reported correlation between nucleus size and cell size. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Learning a musical instrument: The influence of interpersonal interaction on outcomes for school-aged pupils

    OpenAIRE

    Creech, A.; Hallam, S.

    2011-01-01

    Researchers in recent years have increasingly placed an emphasis on seeking pupils' perceptions of educational settings. Alongside this shift towards attaching value to the pupil viewpoint has been a growing interest concerning how interpersonal relationships, manifested as control or responsiveness between teachers and pupils or parents and pupils, impact on learning processes and outcomes. This study aimed first to elicit pupils' perceptions of their interpersonal interactions with teachers...

  10. Controllable microgels from multifunctional molecules: structure control and size distribution

    Science.gov (United States)

    Gu, Zhenyu; Patterson, Gary; Cao, Rong; Armitage, Bruce

    2004-03-01

    Supramolecular microgels with fractal structures were produced by engineered multifunctional molecules. The combination of static and dynamic light scattering was utilized to characterize the fractal dimension (Df) of the microgels and analyze the aggregation process of the microgels. The microgels are assembled from (1) a tetrafunctional protein (avidin), (2) a trifunctional DNA construct known as a three-way junction, and (3) a biotinylated peptide nucleic acid (PNA) that acts as a crosslinker by binding irreversibly to four equivalent binding sites on the protein and thermoreversibly to three identical binding sites on the DNA. The structure of microgels can be controlled through different aggregation mechanisms. The initial microgels formed by titration have a compact structure with Df ˜2.6; while the reversible microgels formed from melted aggregates have an open structure with Df ˜1.8. The values are consistent with the point-cluster and the cluster-cluster aggregation mechanisms, respectively. A narrow size distribution of microgels was observed and explained in terms of the Flory theory of reversible self-assembly.

  11. Assessing Pupils' Progress

    Science.gov (United States)

    Ollerton, Mike

    2010-01-01

    In this article, the author explores what Assessing Pupils' Progress (APP) is about. He contends that the predilection for testing is a catastrophe as far as the teaching and learning of mathematics is concerned; it is an outcome of the drive for collecting so-called "data" on pupils. What those people, who should know better, either choose to…

  12. Creating Pupils' Internet Magazine

    Science.gov (United States)

    Bognar, Branko; Šimic, Vesna

    2014-01-01

    This article presents an action research, which aimed to improve pupils' literary creativity and enable them to use computers connected to the internet. The study was conducted in a small district village school in Croatia. Creating a pupils' internet magazine appeared to be an excellent way for achieving the educational aims of almost all…

  13. Pupil Alignment Considerations for Large, Deployable Space Telescopes

    Science.gov (United States)

    Bos, Brent J.; Ohl, Raymond G.; Kubalak, Daivd A.

    2011-01-01

    For many optical systems the properties and alignment of the internal apertures and pupils are not critical or controlled with high precision during optical system design, fabrication or assembly. In wide angle imaging systems, for instance, the entrance pupil position and orientation is typically unconstrained and varies over the system s field of view in order to optimize image quality. Aperture tolerances usually do not receive the same amount of scrutiny as optical surface aberrations or throughput characteristics because performance degradation is typically graceful with misalignment, generally only causing a slight reduction in system sensitivity due to vignetting. But for a large deployable space-based observatory like the James Webb Space Telescope (JWST), we have found that pupil alignment is a key parameter. For in addition to vignetting, JWST pupil errors cause uncertainty in the wavefront sensing process that is used to construct the observatory on-orbit. Furthermore they also open stray light paths that degrade the science return from some of the telescope s instrument channels. In response to these consequences, we have developed several pupil measurement techniques for the cryogenic vacuum test where JWST science instrument pupil alignment is verified. These approaches use pupil alignment references within the JWST science instruments; pupil imaging lenses in three science instrument channels; and unique pupil characterization features in the optical test equipment. This will allow us to verify and crosscheck the lateral pupil alignment of the JWST science instruments to approximately 1-2% of their pupil diameters.

  14. Use of surfactants to control island size and density

    Energy Technology Data Exchange (ETDEWEB)

    Merrell, Jason; Liu, Feng; Stringfellow, Gerald B.

    2017-08-15

    Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.

  15. Particle size control of detergents in mixed flow spray dryers

    Directory of Open Access Journals (Sweden)

    Mark Jonathan Crosby

    2015-03-01

    Full Text Available Particle size is a key quality parameter of a powder detergent as it determines its performance, the bulk density and the look and feel of the product. Consequently, it is essential that particle size is controlled to ensure the consistency of performance when comparing new formulations. The majority of study reported in the literature relating to particle size control, focuses on the spray produced by the atomisation technique. One approach advocated to achieve particle size control is the manipulation of the ratio of the mass slurry rate and mass flow rate of gas used for atomisation. Within this study, ratio control was compared with an automatic cascade loop approach using online measurements of the powder particle size on a small-scale pilot plant. It was concluded that cascade control of the mean particle size, based on manipulating the mass flow rate of gas, resulted in tighter, more responsive control. The effect of a ratio change varied with different formulations and different slurry rates. Furthermore, changes in slurry rate caused complications, as the impact on particle size growth in the dryer is non-linear and difficult to predict. The cascade loop enables further study into the effect of particle size on detergent performance.

  16. Cell size control - a mechanism for maintaining fitness and function.

    Science.gov (United States)

    Miettinen, Teemu P; Caldez, Matias J; Kaldis, Philipp; Björklund, Mikael

    2017-09-01

    The maintenance of cell size homeostasis has been studied for years in different cellular systems. With the focus on 'what regulates cell size', the question 'why cell size needs to be maintained' has been largely overlooked. Recent evidence indicates that animal cells exhibit nonlinear cell size dependent growth rates and mitochondrial metabolism, which are maximal in intermediate sized cells within each cell population. Increases in intracellular distances and changes in the relative cell surface area impose biophysical limitations on cells, which can explain why growth and metabolic rates are maximal in a specific cell size range. Consistently, aberrant increases in cell size, for example through polyploidy, are typically disadvantageous to cellular metabolism, fitness and functionality. Accordingly, cellular hypertrophy can potentially predispose to or worsen metabolic diseases. We propose that cell size control may have emerged as a guardian of cellular fitness and metabolic activity. © 2017 WILEY Periodicals, Inc.

  17. Revisionist integral deferred correction with adaptive step-size control

    KAUST Repository

    Christlieb, Andrew

    2015-03-27

    © 2015 Mathematical Sciences Publishers. Adaptive step-size control is a critical feature for the robust and efficient numerical solution of initial-value problems in ordinary differential equations. In this paper, we show that adaptive step-size control can be incorporated within a family of parallel time integrators known as revisionist integral deferred correction (RIDC) methods. The RIDC framework allows for various strategies to implement stepsize control, and we report results from exploring a few of them.

  18. Accommodation and pupil responses to random-dot stereograms.

    Science.gov (United States)

    Suryakumar, Rajaraman; Allison, Robert

    2016-01-01

    We investigated the dynamics of accommodative and pupillary responses to random-dot stereograms presented in crossed and uncrossed disparity in six visually normal young adult subjects (mean age=25.8±3.1 years). Accommodation and pupil measures were monitored monocularly with a custom built photorefraction system while subjects fixated at the center of a random-dot stereogram. On each trial, the stereogram initially depicted a flat plane and then changed to depict a sinusoidal corrugation in depth while fixation remained constant. Increase in disparity specified depth resulted in pupil constriction during both crossed and uncrossed disparity presentations. The change in pupil size between crossed and uncrossed disparity conditions was not significantly different (p>0.05). The change in pupil size was also accompanied by a small concomitant increase in accommodation. In addition, the dynamic properties of pupil responses varied as a function of their initial (starting) diameter. The finding that accommodation and pupil responses increased with disparity regardless of the sign of retinal disparity suggests that these responses were driven by apparent depth rather than shifts in mean simulated distance of the stimulus. Presumably the need for the increased depth of focus when viewing stimuli extended in depth results in pupil constriction which also results in a concomitant change in accommodation. Starting position effects in pupil response confirm the non-linearity in the operating range of the pupil.

  19. Cognitive and Ocular Factors Jointly Determine Pupil Responses under Equiluminance

    NARCIS (Netherlands)

    Knapen, T.; de Gee, J.W.; Brascamp, J.; Nuiten, S.; Hoppenbrouwers, S.; Theeuwes, J.

    2016-01-01

    Changes in pupil diameter can reflect high-level cognitive signals that depend on central neuromodulatory mechanisms. However, brain mechanisms that adjust pupil size are also exquisitely sensitive to changes in luminance and other events that would be considered a nuisance in cognitive experiments

  20. Pupils' Understanding of Air Pollution

    Science.gov (United States)

    Dimitriou, Anastasia; Christidou, Vasilia

    2007-01-01

    This paper reports on a study of pupils' knowledge and understanding of atmospheric pollution. Specifically, the study is aimed at identifying: 1) the extent to which pupils conceptualise the term "air pollution" in a scientifically appropriate way; 2) pupils' knowledge of air pollution sources and air pollutants; and 3) pupils' knowledge of air…

  1. 屈光手术前个体眼高阶像差与中间视觉状态下瞳孔大小%Ocular higher-order aberrations and mesopic pupil size in individuals screened for refractive surgery

    Institute of Scientific and Technical Information of China (English)

    Seyed Javad Hashemian; Mohammad Soleimani; Alireza Foroutan; Mahmood Joshaghani; Mohammad Jafar Ghaempanah; Mohammad Ebrahim Jafari; Mehdi Yaseri

    2012-01-01

    目的:研究眼高阶像差的分布(HOAs)和mesopic瞳孔的大小在个体中筛选的屈光手术.方法:我们采用Zywave像差分析仪(博士伦)分别对患有近视、近视散光和复性近视散光患者1 240例2 458眼和患有远视、远视散光和复性远视散光患者110例215眼的高阶像差和瞳孔大小进行检测.所有患者屈光不正均可矫正,无屈光手术史或潜在疾病.HOAs的均方根值、总球面像差、总斜射球面像差和中间视觉状态下瞳孔的大小进行了分析,眼高阶像差测量均在瞳孔≥6.0mm,且瞳孔大小的测量均为在中间视觉状态下进行.结果:HOAs均方根值、总球面像差和总斜射球面像差在近视眼组与远视眼组分别为0.369±0.233μm、0.133±0.112μm、0.330±0.188μm;0.418±0.214μm、0.202±0.209μm、0.343±0.201μm.与近视患者相比,远视患者的总HOAs和总球面像差更大(P均<0.01).年龄匹配分析显示在远视眼组只有总球面像差较高(P=0.05).近视眼组的中间视觉状态下瞳孔大小较大(P≤0.05).结论:实验结果表明两组的HOAs的水平有显著差异,这对于将行屈光手术的伊朗人很重要.远视眼组的总球面像差显著高于近视眼组,中间视觉状态下瞳孔大小在近视眼组较大.%AIM: To study the distribution of ocular higher-order aberrations(HOAs) and mesopic pupil size in individuals screened for refractive surgery.patients with myopia, myopic astigmatism and compound myopic astigmatism and 215 eyes of 110 patients with hyperopia, hyperopic astigmatism and compound hyperopic astigmatism using the Zywave aberrometer (Busch& Lomb). All patients had correctable refractive errors without a history of refractive surgery or underlying diseases. Root-mean-square values of HOAs, total spherical aberration, total coma and mesopic pupil size were analyzed. Ocular HOAs were measured across a ≥6.0mm pupil, and pupil size measurements were performed under the mesopic condition. the

  2. Tonic pupil in leprosy

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Lana-Peixoto

    2014-12-01

    Full Text Available Pupil abnormalities in leprosy usually result from chronic iritis with loss of stroma, iris miosis, a sluggish reaction to light, and poor dilation in response to anticholinergic mydriatics. We report two patients with long-standing lepromatous leprosy who developed tonic pupils characterized by mydriasis, absence of reaction to light and hypersensitivity to weak cholinergic solution. Examination revealed iritis and iris atrophy. In both cases, instillation of dilute 0.1% pilocarpine caused miosis in the affected eyes. Tonic pupil occurs in many conditions, but its association with leprosy had not been previously reported.

  3. The size-wise nucleus: nuclear volume control in eukaryotes.

    Science.gov (United States)

    Huber, Michael D; Gerace, Larry

    2007-11-19

    Eukaryotic cells have an "awareness" of their volume and organellar volumes, and maintain a nuclear size that is proportional to the total cell size. New studies in budding and fission yeast have examined the relationship between cell and nuclear volumes. It was found that the size of the nucleus remains proportional to cell size in a wide range of genetic backgrounds and growth conditions that alter cell volume and DNA content. Moreover, in multinucleated fission yeast cells, Neumann and Nurse (see p. 593 of this issue) found that the sizes of individual nuclei are controlled by the relative amount of cytoplasm surrounding each nucleus. These results highlight a role of the cytoplasm in nuclear size control.

  4. Calculating sample size in trials using historical controls.

    Science.gov (United States)

    Zhang, Song; Cao, Jing; Ahn, Chul

    2010-08-01

    Makuch and Simon [Sample size considerations for non-randomised comparative studies. J Chronic Dis 1980; 33: 175-81.] developed a sample size formula for historical control trials. When assessing power, they assumed the true control treatment effect to be equal to the observed effect from the historical control group. Many researchers have pointed out that the Makuch-Simon approach does not preserve the nominal power and type I error when considering the uncertainty in the true historical control treatment effect. To develop a sample size formula that properly accounts for the underlying randomness in the observations from the historical control group. We reveal the extremely skewed nature in the distributions of power and type I error, obtained over all the random realizations of the historical control data. The skewness motivates us to derive a sample size formula that controls the percentiles, instead of the means, of the power and type I error. A closed-form sample size formula is developed to control arbitrary percentiles of power and type I error for historical control trials. A simulation study further demonstrates that this approach preserves the operational characteristics in a more realistic scenario where the population variances are unknown and replaced by sample variances. The closed-form sample size formula is derived for continuous outcomes. The formula is more complicated for binary or survival time outcomes. We have derived a closed-form sample size formula that controls the percentiles instead of means of power and type I error in historical control trials, which have extremely skewed distributions over all the possible realizations of historical control data.

  5. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    Science.gov (United States)

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  6. Influence of graphic design of the text on reading quality of pupils with dyslexia

    Directory of Open Access Journals (Sweden)

    Zikl Pavel

    2016-01-01

    Full Text Available The contribution contains research results focused on reading quality of pupils with dyslexia according to the graphic design of the text. Our aim was to prove if commonly recommended graphic text editing has a certain influence on reading speed and occurrence of mistakes of children with dyslexia. The research sample consisted of pupils with dyslexia and a control group then selected in pairs of intact pupils of 4th and 5th class of primary school (in total 150 pupils. For the purpose of data collection there had been a text used in an unfamiliar language (a nonsensical text, which corresponds to the Czech language in its structure; is a part of standardized reading test. There were four text versions prepared for the research which had been modified into frequently recommended modifications for dyslexics (increased font size, a use of bigger gaps between words and also rows, syllables highlight in words and a standard text corresponding to common reading-books. Conclusion depicts a presentation of impacts of individual texts modifications and also subjective opinions of pupils about these texts.

  7. Size Controlled Synthesis of Starch Nanoparticles by a Microemulsion Method

    Directory of Open Access Journals (Sweden)

    Suk Fun Chin

    2014-01-01

    Full Text Available Controllable particles sizes of starch nanoparticles were synthesized via a precipitation in water-in-oil microemulsion approach. Microemulsion method offers the advantages of ultralow interfacial tension, large interfacial area, and being thermodynamically stable and affords monodispersed nanoparticles. The synthesis parameters such as stirring rates, ratios of oil/cosurfactant, oil phases, cosurfactants, and ratios of water/oil were found to affect the mean particle size of starch nanoparticles. Starch nanoparticles with mean particles sizes of 109 nm were synthesized by direct nanoprecipitation method, whereas by using precipitation in microemulsion approach, starch nanoparticles with smaller mean particles sizes of 83 nm were obtained.

  8. Anisoplanatism in adaptive optics systems due to pupil aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B

    2005-08-01

    Adaptive optics systems typically include an optical relay that simultaneously images the science field to be corrected and also a set of pupil planes conjugate to the deformable mirror of the system. Often, in the optical spaces where DM's are placed, the pupils are aberrated, leading to a displacement and/or distortion of the pupil that varies according to field position--producing a type of anisoplanatism, i.e., a degradation of the AO correction with field angle. The pupil aberration phenomenon is described and expressed in terms of Seidel aberrations. An expression for anisoplanatism as a function of pupil distortion is derived, an example of an off-axis parabola is given, and a convenient method for controlling pupil-aberration-generated anisoplanatism is proposed.

  9. Safety and efficacy of phacoemulsification and intraocular lens implantation through a small pupil using minimal iris manipulation

    Directory of Open Access Journals (Sweden)

    Papaconstantinou D

    2016-05-01

    Full Text Available Dimitris Papaconstantinou, George Kalantzis, Dimitris Brouzas, Anastasios Kontaxakis, Chryssanthi Koutsandrea, Andreas Diagourtas, Ilias Georgalas Department of Ophthalmology, National and Kapodistrian University of Athens, Athens, Greece Purpose: The aim of this study was to compare the results of phacoemulsification through a small pupil using minimal iris manipulation versus phacoemulsification through a well-dilated pupil.Methods: This prospective randomized control (comparative study comprised 78 patients (group I with a maximally dilated pupil size of ≤4.00 mm and 45 patients (group II with dilated pupil size of ≥7.00 mm. In group I patients, only viscodilation and minimal push-and-pull iris stretching with two collar-button iris-retractor hooks were utilized without iris manipulation. Phacoemulsification was performed by two senior surgeons and the technique used consisted of either stop and chop or quick chop, infusion/aspiration of lens cortex, capsular bag refill with ocular viscoelastic devices, and implantation of an acrylic foldable intraocular lens. Patients were examined on the first day and 1 month postoperatively.Results: Forty-six eyes of group I patients had pseudoexfoliation syndrome, eleven eyes had previous glaucoma surgery, 14 eyes had angle-closure or open-angle glaucoma, and seven eyes had posterior synechiae with iritis. In group I patients, the mean pupil size measured under an operating microscope was 3.2 mm preoperatively, 4.3 mm after viscoelastic and mechanical pupil dilation, and 4.1 mm at the end of a surgical procedure. Rupture of the zonular fibers occurred in six patients of group I and the intraocular lens was implanted in the sulcus. Small iris-sphincter rupture and small hemorrhages occurred in four eyes during pupillary manipulation, but they were not evident at the end of the surgery. In group II patients, no intraoperative complications occurred. Signs of significant corneal edema and iritis

  10. Rock sampling. [method for controlling particle size distribution

    Science.gov (United States)

    Blum, P. (Inventor)

    1971-01-01

    A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

  11. Optimal pupil apodizations for arbitrary apertures

    CERN Document Server

    Carlotti, A; Kasdin, N J

    2011-01-01

    We present here fully optimized two-dimensional pupil apodizations for which no specific geometric constraints are put on the pupil plane apodization, apart from the shape of the aperture itself. Masks for circular and segmented apertures are displayed, with and without central obstruction and spiders. Examples of optimal masks are shown for Subaru, SPICA and JWST. Several high-contrast regions are considered with different sizes, positions, shapes and contrasts. It is interesting to note that all the masks that result from these optimizations tend to have a binary transmission profile.

  12. Bilayer thickness mismatch controls domain size in biomimetic membranes

    Science.gov (United States)

    Heberle, Frederick A.; Petruzielo, Robin S.; Pan, Jianjun; Drazba, Paul; Kučerka, Norbert; Standaert, Robert F.; Feigenson, Gerald W.; Katsara, John

    2013-03-01

    In order to promote functionality, cells may alter the spatial organization of membrane lipids and proteins, including separation of liquid phases into distinct domains. In model membranes, domain size and morphology depend strongly on composition and temperature, but the physicochemical mechanisms controlling them are poorly understood. Theoretical work suggests a role for interfacial energy at domain boundaries, which may be driven in part by thickness mismatch between a domain and its surrounding bilayer. However, no direct evidence linking thickness mismatch to domain size in free-standing bilayers has been reported. We describe the use of Small Angle Neutron Scattering (SANS) to detect domains in simplified lipid-only models that mimic the composition of plasma membrane. We find that domain size is controlled by the degree of acyl chain unsaturation of low-melting temperature lipids, and that this size transition is correlated to changes in the thickness mismatch between coexisting liquid phases.

  13. Pupil-linked arousal determines variability in perceptual decision making

    National Research Council Canada - National Science Library

    Murphy, Peter R; Vandekerckhove, Joachim; Nieuwenhuis, Sander

    2014-01-01

    .... We measured pupil size, a highly sensitive index of arousal, while human subjects performed a motion-discrimination task, and decomposed task behavior into latent decision making parameters using...

  14. Minimizing the Bright/Shadow Focal Spot Size with Controlled Side-Lobe Increase in High-Numerical-Aperture Focusing Systems

    Directory of Open Access Journals (Sweden)

    S. N. Khonina

    2013-01-01

    Full Text Available Minimizing the bright/shadow focal spot size for differently polarized incident waves through the additional apodization of the focusing system output pupil by use of an optical element with the vortex phase dependence on angle and the polynomial amplitude dependence on radius is studied. The coefficients of the radial polynomial were optimized with the aim of fulfilling certain conditions such as the energy efficiency preservation and keeping the side lobes under control. The coefficients were chosen so as to minimize the functional using Brent’s method.

  15. Controlling Silver Nanoparticle Size and Morphology with Photostimulated Synthesis

    CERN Document Server

    Popov, A K; Langlois, R; Loth, M; Schmitz, R; Taft, G; Tanke, R S; Wruck, A

    2005-01-01

    Photo-induced synthesis and control over the size and shape of colloidal silver nanoparticles is investigated in contrast to photo-stimulated aggregation of small nanoparticles into large fractal-type structures. The feasibility of light-driven nanoengineering which enables manipulation of the sizes and shapes of the isolated nanoparticles is studied by varying the amount and type of the stabilizing agent and the type of optical irradiation.

  16. Pupil-mimicry conditions trust in partners: moderation by oxytocin and group membership.

    Science.gov (United States)

    Kret, Mariska E; De Dreu, Carsten K W

    2017-03-15

    Across species, oxytocin, an evolutionarily ancient neuropeptide, facilitates social communication by attuning individuals to conspecifics' social signals, fostering trust and bonding. The eyes have an important signalling function; and humans use their salient and communicative eyes to intentionally and unintentionally send social signals to others, by contracting the muscles around their eyes and pupils. In our earlier research, we observed that interaction partners with dilating pupils are trusted more than partners with constricting pupils. But over and beyond this effect, we found that the pupil sizes of partners synchronize and that when pupils synchronously dilate, trust is further boosted. Critically, this linkage between mimicry and trust was bound to interactions between ingroup members. The current study investigates whether these findings are modulated by oxytocin and sex of participant and partner. Using incentivized trust games with partners from ingroup and outgroup whose pupils dilated, remained static or constricted, this study replicates our earlier findings. It further reveals that (i) male participants withhold trust from partners with constricting pupils and extend trust to partners with dilating pupils, especially when given oxytocin rather than placebo; (ii) female participants trust partners with dilating pupils most, but this effect is blunted under oxytocin; (iii) under oxytocin rather than placebo, pupil dilation mimicry is weaker and pupil constriction mimicry stronger; and (iv) the link between pupil constriction mimicry and distrust observed under placebo disappears under oxytocin. We suggest that pupil-contingent trust is parochial and evolved in social species in and because of group life.

  17. Isotropic 2D quadrangle meshing with size and orientation control

    KAUST Repository

    Pellenard, Bertrand

    2011-12-01

    We propose an approach for automatically generating isotropic 2D quadrangle meshes from arbitrary domains with a fine control over sizing and orientation of the elements. At the heart of our algorithm is an optimization procedure that, from a coarse initial tiling of the 2D domain, enforces each of the desirable mesh quality criteria (size, shape, orientation, degree, regularity) one at a time, in an order designed not to undo previous enhancements. Our experiments demonstrate how well our resulting quadrangle meshes conform to a wide range of input sizing and orientation fields.

  18. Results of a Survey of Pupils and Teachers Regarding Television.

    Science.gov (United States)

    Crawford, Patricia; Rapoport, Max

    To test the validity of hypotheses regarding television violence and social behavior of viewers, a survey was conducted of a large stratified sample of sixth grade and kindergarten pupils and of teachers. The student survey identified: (1) frequency with which pupils watch television; (2) parental control of television viewing; (3) family…

  19. Time-domain analysis for extracting fast-paced pupil responses

    Science.gov (United States)

    Zénon, Alexandre

    2017-01-01

    The eye pupil reacts to cognitive processes, but its analysis is challenging when luminance varies or when stimulation is fast-paced. Current approaches relying on deconvolution techniques do not account for the strong low-frequency spontaneous changes in pupil size or the large interindividual variability in the shape of the responses. Here a system identification framework is proposed in which the pupil responses to different parameters are extracted by means of an autoregressive model with exogenous inputs. In an example application of this technique, pupil size was shown to respond to the luminance and arousal scores of affective pictures presented in rapid succession. This result was significant in each subject (N = 5), but the pupil response varied between individuals both in amplitude and latency, highlighting the need for determining impulse responses subjectwise. The same method was also used to account for pupil size variations caused by respiration, illustrating the possibility to model the relation between pupil size and other continuous signals. In conclusion, this new framework for the analysis of pupil size data allows us to dissociate the response of the eye pupil from intermingled sources of influence and can be used to study the relation between pupil size and other physiological signals. PMID:28134323

  20. Sonochemical synthesis of silica particles and their size control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

    2016-09-01

    Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: Using an ultrasound-assisted sol–gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

  1. Combined Optimal Sizing and Control for a Hybrid Tracked Vehicle

    Directory of Open Access Journals (Sweden)

    Huei Peng

    2012-11-01

    Full Text Available The optimal sizing and control of a hybrid tracked vehicle is presented and solved in this paper. A driving schedule obtained from field tests is used to represent typical tracked vehicle operations. Dynamics of the diesel engine-permanent magnetic AC synchronous generator set, the lithium-ion battery pack, and the power split between them are modeled and validated through experiments. Two coupled optimizations, one for the plant parameters, forming the outer optimization loop and one for the control strategy, forming the inner optimization loop, are used to achieve minimum fuel consumption under the selected driving schedule. The dynamic programming technique is applied to find the optimal controller in the inner loop while the component parameters are optimized iteratively in the outer loop. The results are analyzed, and the relationship between the key parameters is observed to keep the optimal sizing and control simultaneously.

  2. Separability Filter for Localizing Abnormal Pupil: Identification Criteria of Input Image

    Directory of Open Access Journals (Sweden)

    Tutik Ida Rosanti

    2013-11-01

    Full Text Available Separability filter method is a reliable method for pupil detection. However, so far this method is implemented for detecting pupil of normal eye, while for abnormal eye such as cataract and glaucoma patients; they have different characteristics of pupil such as color, shape and radius size of pupil. In this paper we propose to use separability filter for detecting pupil of abnormal patients with different characteristics. We faced a problem about radius size, shape and color of pupil; therefore we implemented Hough Transform, Blob area and Brightness for identifying input images before applying separability filter. The experiment results show that we can increase performance of pupil detection for abnormal eye to be 95.65%.

  3. Automated Control Surface Design and Sizing for the Prandtl Plane

    NARCIS (Netherlands)

    Van Ginneken, D.A.J.; Voskuijl, M.; Van Tooren, M.J.L.; Frediani, A.

    2010-01-01

    This paper presents a methodology for the design of the primary flight control surfaces, in terms of size, number and location, for fixed wing aircraft (conventional or unconventional). As test case, the methodology is applied to a 300 passenger variant of the Prandtl Plane. This box wing aircraft i

  4. Method of controlling crystallite size in nuclear-reactor fuels

    Science.gov (United States)

    Lloyd, M.H.; Collins, J.L.; Shell, S.E.

    Improved spherules for making enhanced forms of nuclear-reactor fuels are prepared by internal gelation procedures within a sol-gel operation and are accomplished by first boiling the concentrated HMTA-urea feed solution before engaging in the spherule-forming operation thereby effectively controlling crystallite size in the product spherules.

  5. Koehler-illumination-based method to improve beam size controllability

    Science.gov (United States)

    Hattori, Kiyoshi; Sunaoshi, Hitoshi; Ando, Atsushi

    1998-06-01

    We have developed a new EB calibration method for adjusting both Koehler illumination condition and beam current density precisely in the EB direct writing system EX-8D. Koehler illumination condition is adjusted by controlling the condenser lens so that the beam size change on the target vs. focus change of the objective is minimized. Beam current density is adjusted to the desired value by controlling the two condenser lenses which acts as a zoom lens function and maintaining above Koehler illumination condition. Using this method, beam size deviation was improved to less than 2 nm for a focus change of 10 micrometers , and beam current density was controlled to less than 0.5 percent error from the desired value. This beam calibration was executed in less than 10 minutes. We have also evaluated the pattern roughness and the pattern size deviation depending on the focus change by delineating a 0.125 micrometers line and space pattern. The pattern roughness was controlled to less than 2 nm and the pattern size deviation was less than 2 nm for a focus change of +/- micrometers .

  6. Sample size considerations for historical control studies with survival outcomes

    Science.gov (United States)

    Zhu, Hong; Zhang, Song; Ahn, Chul

    2015-01-01

    Historical control trials (HCTs) are frequently conducted to compare an experimental treatment with a control treatment from a previous study, when they are applicable and favored over a randomized clinical trial (RCT) due to feasibility, ethics and cost concerns. Makuch and Simon developed a sample size formula for historical control (HC) studies with binary outcomes, assuming that the observed response rate in the HC group is the true response rate. This method was extended by Dixon and Simon to specify sample size for HC studies comparing survival outcomes. For HC studies with binary and continuous outcomes, many researchers have shown that the popular Makuch and Simon method does not preserve the nominal power and type I error, and suggested alternative approaches. For HC studies with survival outcomes, we reveal through simulation that the conditional power and type I error over all the random realizations of the HC data have highly skewed distributions. Therefore, the sampling variability of the HC data needs to be appropriately accounted for in determining sample size. A flexible sample size formula that controls arbitrary percentiles, instead of means, of the conditional power and type I error, is derived. Although an explicit sample size formula with survival outcomes is not available, the computation is straightforward. Simulations demonstrate that the proposed method preserves the operational characteristics in a more realistic scenario where the true hazard rate of the HC group is unknown. A real data application of an advanced non-small cell lung cancer (NSCLC) clinical trial is presented to illustrate sample size considerations for HC studies in comparison of survival outcomes. PMID:26098200

  7. Learning a Musical Instrument: The Influence of Interpersonal Interaction on Outcomes for School-Aged Pupils

    Science.gov (United States)

    Creech, Andrea; Hallam, Susan

    2011-01-01

    Researchers in recent years have increasingly placed an emphasis on seeking pupils' perceptions of educational settings. Alongside this shift towards attaching value to the pupil viewpoint has been a growing interest concerning how interpersonal relationships, manifested as control or responsiveness between teachers and pupils or parents and…

  8. Cryogenic Pupil Alignment Test Architecture for Aberrated Pupil Images

    Science.gov (United States)

    Bos, Brent; Kubalak, David A.; Antonille, Scott; Ohl, Raymond; Hagopian, John G.

    2009-01-01

    A document describes cryogenic test architecture for the James Webb Space Telescope (JWST) integrated science instrument module (ISIM). The ISIM element primarily consists of a mechanical metering structure, three science instruments, and a fine guidance sensor. One of the critical optomechanical alignments is the co-registration of the optical telescope element (OTE) exit pupil with the entrance pupils of the ISIM instruments. The test architecture has been developed to verify that the ISIM element will be properly aligned with the nominal OTE exit pupil when the two elements come together. The architecture measures three of the most critical pupil degrees-of-freedom during optical testing of the ISIM element. The pupil measurement scheme makes use of specularly reflective pupil alignment references located inside the JWST instruments, ground support equipment that contains a pupil imaging module, an OTE simulator, and pupil viewing channels in two of the JWST flight instruments. Pupil alignment references (PARs) are introduced into the instrument, and their reflections are checked using the instrument's mirrors. After the pupil imaging module (PIM) captures a reflected PAR image, the image will be analyzed to determine the relative alignment offset. The instrument pupil alignment preferences are specularly reflective mirrors with non-reflective fiducials, which makes the test architecture feasible. The instrument channels have fairly large fields of view, allowing PAR tip/tilt tolerances on the order of 0.5deg.

  9. Size Controlled Synthesis of Transition Metal Nanoparticles for Catalytic Applications

    KAUST Repository

    Esparza, Angel

    2011-07-07

    Catalysis offers cleaner and more efficient chemical reactions for environmental scientists. More than 90% of industrial processes are performed with a catalyst involved, however research it is still required to improve the catalyst materials. The purpose of this work is to contribute with the development of catalysts synthesis with two different approaches. First, the precise size control of non-noble metals nanoparticles. Second, a new one-pot synthesis method based on a microemulsion system was developed to synthesize size-controlled metal nanoparticles in oxide supports. The one-pot method represents a simple approach to synthesize both support and immobilized nanometer-sized non-noble metal nanoparticles in the same reaction system. Narrow size distribution nickel, cobalt, iron and cobalt-nickel nanoparticles were obtained. High metal dispersions are attainable regardless the metal or support used in the synthesis. Thus, the methodology is adaptable and robust. The sizecontrolled supported metal nanoparticles offer the opportunity to study size effects and metal-support interactions on different catalytic reactions with different sets of metals and supports.

  10. Safety and efficacy of phacoemulsification and intraocular lens implantation through a small pupil using minimal iris manipulation

    Science.gov (United States)

    Papaconstantinou, Dimitris; Kalantzis, George; Brouzas, Dimitris; Kontaxakis, Anastasios; Koutsandrea, Chryssanthi; Diagourtas, Andreas; Georgalas, Ilias

    2016-01-01

    Purpose The aim of this study was to compare the results of phacoemulsification through a small pupil using minimal iris manipulation versus phacoemulsification through a well-dilated pupil. Methods This prospective randomized control (comparative) study comprised 78 patients (group I) with a maximally dilated pupil size of ≤4.00 mm and 45 patients (group II) with dilated pupil size of ≥7.00 mm. In group I patients, only viscodilation and minimal push-and-pull iris stretching with two collar-button iris-retractor hooks were utilized without iris manipulation. Phacoemulsification was performed by two senior surgeons and the technique used consisted of either stop and chop or quick chop, infusion/aspiration of lens cortex, capsular bag refill with ocular viscoelastic devices, and implantation of an acrylic foldable intraocular lens. Patients were examined on the first day and 1 month postoperatively. Results Forty-six eyes of group I patients had pseudoexfoliation syndrome, eleven eyes had previous glaucoma surgery, 14 eyes had angle-closure or open-angle glaucoma, and seven eyes had posterior synechiae with iritis. In group I patients, the mean pupil size measured under an operating microscope was 3.2 mm preoperatively, 4.3 mm after viscoelastic and mechanical pupil dilation, and 4.1 mm at the end of a surgical procedure. Rupture of the zonular fibers occurred in six patients of group I and the intraocular lens was implanted in the sulcus. Small iris-sphincter rupture and small hemorrhages occurred in four eyes during pupillary manipulation, but they were not evident at the end of the surgery. In group II patients, no intraoperative complications occurred. Signs of significant corneal edema and iritis were observed more frequently in group I eyes (26 eyes and 20 eyes, respectively) on the first postoperative day in comparison with group II eyes (ten eyes and six eyes, respectively). Intraocular pressure was <20 mmHg in all eyes of both groups. One month

  11. Synthesis of SAPO-56 with controlled crystal size

    Science.gov (United States)

    Wu, Ting; Feng, Xuhui; Carreon, Maria L.; Carreon, Moises A.

    2017-03-01

    Herein, we present the hydrothermal synthesis of SAPO-56 crystals with relatively controlled crystal/particle size. The effects of water content, aluminum source, gel composition, stirring, crystallization temperature and time, as well as the incorporation of crystal growth inhibitors during synthesis were systematically investigated. The synthesized SAPO-56 crystals displayed BET surface areas as high as ˜630 m2 g-1 with relative narrow size distribution in the ˜5-60 μm range. Nitrogen BET surface areas in the 451 to 631 m2 g-1 range were observed. Decreasing the crystallization temperature from 220 to 210 °C helped to decrease the average SAPO-56 crystal size. Diluted gel compositions promoted the formation of smaller crystals. Crystal growth inhibitors were found to be helpful in reducing crystal size and narrow the size distribution. Specifically, ˜5 μm SAPO-56 crystals displaying narrow size distribution were synthesized employing aluminum-tri-sec-butoxide as Al source, high water content, and high stirring rates.

  12. Environmental control of natural gap size distribution in tropical forests

    Science.gov (United States)

    Goulamoussène, Youven; Bedeau, Caroline; Descroix, Laurent; Linguet, Laurent; Hérault, Bruno

    2017-01-01

    Natural disturbances are the dominant form of forest regeneration and dynamics in unmanaged tropical forests. Monitoring the size distribution of treefall gaps is important to better understand and predict the carbon budget in response to land use and other global changes. In this study, we model the size frequency distribution of natural canopy gaps with a discrete power law distribution. We use a Bayesian framework to introduce and test, using Monte Carlo Markov chain and Kuo-Mallick algorithms, the effect of local physical environment on gap size distribution. We apply our methodological framework to an original light detecting and ranging dataset in which natural forest gaps were delineated over 30 000 ha of unmanaged forest. We highlight strong links between gap size distribution and environment, primarily hydrological conditions and topography, with large gaps being more frequent on floodplains and in wind-exposed areas. In the future, we plan to apply our methodological framework on a larger scale using satellite data. Additionally, although gap size distribution variation is clearly under environmental control, variation in gap size distribution in time should be tested against climate variability.

  13. Relationships for Learning: Using Pupil Voice to Define Teacher-Pupil Relationships that Enhance Pupil Engagement

    Science.gov (United States)

    Marsh, Helena

    2012-01-01

    This paper is a summary of a pupil voice research project conducted to investigate the influence that teacher-pupil relationships have on pupils' feelings of engagement with their school. The study involved two year groups (12-13 and 14-15 year olds) in a rural secondary school in Cambridgeshire. Data sources were collected through a questionnaire…

  14. Magnetic agglomeration method for size control in the synthesis of magnetic nanoparticles

    Science.gov (United States)

    Huber, Dale L [Albuquerque, NM

    2011-07-05

    A method for controlling the size of chemically synthesized magnetic nanoparticles that employs magnetic interaction between particles to control particle size and does not rely on conventional kinetic control of the reaction to control particle size. The particles are caused to reversibly agglomerate and precipitate from solution; the size at which this occurs can be well controlled to provide a very narrow particle size distribution. The size of particles is controllable by the size of the surfactant employed in the process; controlling the size of the surfactant allows magnetic control of the agglomeration and precipitation processes. Agglomeration is used to effectively stop particle growth to provide a very narrow range of particle sizes.

  15. Efficiency optimized control of medium-size induction motor drives

    DEFF Research Database (Denmark)

    Abrahamsen, F.; Blaabjerg, Frede; Pedersen, John Kim

    2000-01-01

    The efficiency of a variable speed induction motor drive can be optimized by adaption of the motor flux level to the load torque. In small drives (... not be disregarded without further analysis. The importance of the converter losses on efficiency optimization in medium-size drives is analyzed in this paper. Based on the experiments with a 90 kW drive it is found that it is not critical if the converter losses are neglected in the control, except...... that the robustness towards load disturbances may unnecessarily be reduced. Both displacement power factor and model-based efficiency optimizing control methods perform well in medium-size drives. The last strategy is also tested on a 22 kW drive with good results....

  16. Efficiency optimized control of medium-size induction motor drives

    DEFF Research Database (Denmark)

    Abrahamsen, F.; Blaabjerg, Frede; Pedersen, John Kim;

    2000-01-01

    The efficiency of a variable speed induction motor drive can be optimized by adaption of the motor flux level to the load torque. In small drives (... not be disregarded without further analysis. The importance of the converter losses on efficiency optimization in medium-size drives is analyzed in this paper. Based on the experiments with a 90 kW drive it is found that it is not critical if the converter losses are neglected in the control, except...... that the robustness towards load disturbances may unnecessarily be reduced. Both displacement power factor and model-based efficiency optimizing control methods perform well in medium-size drives. The last strategy is also tested on a 22 kW drive with good results....

  17. Energy conservation potential of Portland Cement particle size distribution control

    Energy Technology Data Exchange (ETDEWEB)

    Tresouthick, S.W.

    1985-01-01

    The main objective of Phase 3 is to develop practical economic methods of controlling the particle size distribution of portland cements using existing or modified mill circuits with the principal aim of reducing electrical energy requirements for cement manufacturing. The work of Phase 3, because of its scope, will be carried out in 10 main tasks, some of which will be handled simultaneously. Progress on each of these tasks is discussed in this paper.

  18. EFFICIENCY OF READING COMPREHENSION TRAINING IN PUPILS LIVING IN POVERTY

    Directory of Open Access Journals (Sweden)

    Milena Kosak Babuder

    2015-09-01

    Full Text Available The results of Slovene and foreign studies reveal the connection between literacy levels and the level of education, employment opportunities and consequent socio-economic status of individuals and families. Reading efficiency relating to reading comprehension is an important element of reading literacy performance. The findings of several authors indicate empirical evidence of the existence of deficits and poor reading comprehension in pupils living in poverty and stress the importance of offsetting deficits and developing reading comprehension. Results of both foreign and Slovene studies indicate that the program of reading comprehension should be implemented in this group of pupils. In the article, we want to present effectiveness of the reading comprehension improvement program in pupils living in poverty. According to the findings of our research, in which we structured and implemented the reading comprehension program for pupils living in poverty with the Metacognitive-intersentential model of reading comprehension, the reading comprehension of the experimental group pupils who participated in the program improved compared to the control group pupils who did not participate in the program. Experimental group pupils also significantly improved correctness of their reading, their vocabulary and skills of verbal expression. When the program ended, we tested its efficiency by applied tests. The results on the manifest variables indicated that the program was good and efficient for pupils who live in poverty and experience reading comprehension problems.

  19. Make pupils young researchers!

    Science.gov (United States)

    Gouhier, Armelle

    2015-04-01

    With the 2011 educational reform in France, a new course has been created in secondary schools : Methods & Practices in Science (MPS). The main goal was to improve the pupils working methods in science, including laboratory and field works. In addition, the pedagogy develops pupils autonomy and creativity, a key factor in a research process. Three teachers are working together (Mathematics, Physics and Geology-Biology), showing how different disciplines complement one another. Eventually, this is aimed at attracting more students in scientific sections. This course is optional, in the "seconde" class in French secondary schools (i.e., for 15 years old students). For the next class, they will have to choose between scientific, economic and literature sections : it is a useful option for them to decide which section has their preference. In my high-school in Clermont-Ferrand, we have chosen a research subject on hydrogeology & water quality improvement in region "Auvergne". The pupils will have to develop and set up appropriate tools to check and improve the water quality, related to different disciplines : - Geology & Biology: hydrogeology, effects of different pollutants on aquatic life, solutions to improve water quality (example of the natural water treatment zone in the lake of "Aydat, Auvergne, France"). - Physics & Chemistry: water potability criteria, pollution tests in water, water treatment plants working. - Mathematics: algorithm development, modeling on excel of the dispersion of pollutants The pedagogy of this course is new in French high-schools : pupils work in groups of three, so as to develop cooperation and autonomy. The teachers give the guidelines at the beginning of each working session, and answer the students questions when necessary. The evaluation is competence-based : instead of a mark, which is the main evaluation method in France, the pupils have to evaluate their own skills. Then, the teachers make an evaluation, and the global process is

  20. Brassinosteroid perception in the epidermis controls root meristem size

    Science.gov (United States)

    Hacham, Yael; Holland, Neta; Butterfield, Cristina; Ubeda-Tomas, Susana; Bennett, Malcolm J.; Chory, Joanne; Savaldi-Goldstein, Sigal

    2011-01-01

    Multiple small molecule hormones contribute to growth promotion or restriction in plants. Brassinosteroids (BRs), acting specifically in the epidermis, can both drive and restrict shoot growth. However, our knowledge of how BRs affect meristem size is scant. Here, we study the root meristem and show that BRs are required to maintain normal cell cycle activity and cell expansion. These two processes ensure the coherent gradient of cell progression, from the apical to the basal meristem. In addition, BR activity in the meristem is not accompanied by changes in the expression level of the auxin efflux carriers PIN1, PIN3 and PIN7, which are known to control the extent of mitotic activity and differentiation. We further demonstrate that BR signaling in the root epidermis and not in the inner endodermis, quiescent center (QC) cells or stele cell files is sufficient to control root meristem size. Interestingly, expression of the QC and the stele-enriched MADS-BOX gene AGL42 can be modulated by BRI1 activity solely in the epidermis. The signal from the epidermis is probably transmitted by a different component than BES1 and BZR1 transcription factors, as their direct targets, such as DWF4 and BRox2, are regulated in the same cells that express BRI1. Taken together, our study provides novel insights into the role of BRs in controlling meristem size. PMID:21270053

  1. Bilayer Thickness Mismatch Controls Domain Size in Model Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Heberle, Frederick A [ORNL; Petruzielo, Robin S [ORNL; Pan, Jianjun [ORNL; Drazba, Paul [ORNL; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Feigenson, Gerald [Cornell University; Katsaras, John [ORNL

    2013-01-01

    The observation of lateral phase separation in lipid bilayers has received considerable attention, especially in connection to lipid raft phenomena in cells. It is widely accepted that rafts play a central role in cellular processes, notably signal transduction. While micrometer-sized domains are observed with some model membrane mixtures, rafts much smaller than 100 nm beyond the reach of optical microscopy are now thought to exist, both in vitro and in vivo. We have used small-angle neutron scattering, a probe free technique, to measure the size of nanoscopic membrane domains in unilamellar vesicles with unprecedented accuracy. These experiments were performed using a four-component model system containing fixed proportions of cholesterol and the saturated phospholipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), mixed with varying amounts of the unsaturated phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dioleoylsn- glycero-3-phosphocholine (DOPC). We find that liquid domain size increases with the extent of acyl chain unsaturation (DOPC:POPC ratio). Furthermore, we find a direct correlation between domain size and the mismatch in bilayer thickness of the coexisting liquid-ordered and liquid-disordered phases, suggesting a dominant role for line tension in controlling domain size. While this result is expected from line tension theories, we provide the first experimental verification in free-floating bilayers. Importantly, we also find that changes in bilayer thickness, which accompany changes in the degree of lipid chain unsaturation, are entirely confined to the disordered phase. Together, these results suggest how the size of functional domains in homeothermic cells may be regulated through changes in lipid composition.

  2. Sample size in orthodontic randomized controlled trials: are numbers justified?

    Science.gov (United States)

    Koletsi, Despina; Pandis, Nikolaos; Fleming, Padhraig S

    2014-02-01

    Sample size calculations are advocated by the Consolidated Standards of Reporting Trials (CONSORT) group to justify sample sizes in randomized controlled trials (RCTs). This study aimed to analyse the reporting of sample size calculations in trials published as RCTs in orthodontic speciality journals. The performance of sample size calculations was assessed and calculations verified where possible. Related aspects, including number of authors; parallel, split-mouth, or other design; single- or multi-centre study; region of publication; type of data analysis (intention-to-treat or per-protocol basis); and number of participants recruited and lost to follow-up, were considered. Of 139 RCTs identified, complete sample size calculations were reported in 41 studies (29.5 per cent). Parallel designs were typically adopted (n = 113; 81 per cent), with 80 per cent (n = 111) involving two arms and 16 per cent having three arms. Data analysis was conducted on an intention-to-treat (ITT) basis in a small minority of studies (n = 18; 13 per cent). According to the calculations presented, overall, a median of 46 participants were required to demonstrate sufficient power to highlight meaningful differences (typically at a power of 80 per cent). The median number of participants recruited was 60, with a median of 4 participants being lost to follow-up. Our finding indicates good agreement between projected numbers required and those verified (median discrepancy: 5.3 per cent), although only a minority of trials (29.5 per cent) could be examined. Although sample size calculations are often reported in trials published as RCTs in orthodontic speciality journals, presentation is suboptimal and in need of significant improvement.

  3. Pinning control of clustered complex networks with different size

    Science.gov (United States)

    Fu, Chenbo; Wang, Jinbao; Xiang, Yun; Wu, Zhefu; Yu, Li; Xuan, Qi

    2017-08-01

    In pinning control of complex networks, it is found that, with the same pinning effort, the network can be better controlled by pinning the large-degree nodes. But in the clustered complex networks, this preferential pinning (PP) strategy is losing its effectiveness. In this paper, we demonstrate that in the clustered complex networks, especially when the clusters have different size, the random pinning (RP) strategy performs much better than the PP strategy. Then, we propose a new pinning strategy based on cluster degree. It is revealed that the new cluster pinning strategy behaves better than RP strategy when there are only a smaller number of pinning nodes. The mechanism is studied by using eigenvalue and eigenvector analysis, and the simulations of coupled chaotic oscillators are given to verify the theoretical results. These findings could be beneficial for the design of control schemes in some practical systems.

  4. Size control by rate control in colloidal PbSe quantum dot synthesis

    Science.gov (United States)

    Čapek, Richard Karel; Yanover, Dianna; Lifshitz, Efrat

    2015-03-01

    A recently demonstrated approach to control the size of colloidal nanoparticles, ``size control by rate control'', which was validated on the examples of colloidal CdSe- and CdS-quantum dot (CQD) synthesis, appears to be a general strategy for designing technically applicable CQD-syntheses. The ``size control by rate control'' concept allows full-yield syntheses of ensembles of CQDs with different sizes by tuning the solute formation rate. In this work, we extended this strategy to dialkylphosphine enhanced hot-injection synthesis of PbSe-CQDs. Furthermore, we provide new insight into the reaction mechanism of dialkylphosphine enhancement in TOPSe based CQD-syntheses.A recently demonstrated approach to control the size of colloidal nanoparticles, ``size control by rate control'', which was validated on the examples of colloidal CdSe- and CdS-quantum dot (CQD) synthesis, appears to be a general strategy for designing technically applicable CQD-syntheses. The ``size control by rate control'' concept allows full-yield syntheses of ensembles of CQDs with different sizes by tuning the solute formation rate. In this work, we extended this strategy to dialkylphosphine enhanced hot-injection synthesis of PbSe-CQDs. Furthermore, we provide new insight into the reaction mechanism of dialkylphosphine enhancement in TOPSe based CQD-syntheses. Electronic supplementary information (ESI) available: Additional data about the reaction and growth kinetics, NMR-data and exemplary TEM images of PbSe-CQDs prepared by the procedure described in this publication. See DOI: 10.1039/c5nr00028a

  5. Walking control of small size humanoid robot: HAJIME ROBOT 18

    Science.gov (United States)

    Sakamoto, Hajime; Nakatsu, Ryohei

    2007-12-01

    HAJIME ROBOT 18 is a fully autonomous biped robot. It has been developed for RoboCup which is a worldwide soccer competition of robots. It is necessary for a robot to have high mobility to play soccer. High speed walking and all directional walking are important to approach and to locate in front of a ball. HAJIME ROBOT achieved these walking. This paper describes walking control of a small size humanoid robot 'HAJIME ROBOT 18' and shows the measurement result of ZMP (Zero Moment Point). HAJIME ROBOT won the Robotics Society of Japan Award in RoboCup 2005 and in RoboCup 2006 Japan Open.

  6. Photocatalytic Properties of Size-Controlled Titania Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Takeshi Hashishin

    2011-01-01

    Full Text Available The titania nanotube arrays (TNAs with smooth surface was synthesized by anodization of titanium foil with 3 cm2 in square area using the electrolyte composed of 0.2 wt% NH4F and 0.5 vol% H2SO4 in ethylene glycol in order to evaluate the methylene blue photodegradation under ultra-violet irradiation. The tube length and inner diameter as a size parameter were controlled by the anodization time from 5 to 10 h and applied voltage from 10 to 50 V. The titania nanotube arrays (TNAs annealed at 300 to 500°C were assigned to anatase phase, and TNAs at 600°C had both phase of anatase and rutile. The crystallite size and the apparent rate constant were increased with the increase in the annealing temperature of TNAs from 300 to 500°C. The bigger crystallite size of TNAs is suggested to be related to the increase in the amount of hole at the valence band, leading to the decrease in the apparent rate constant of MB degradation. Interestingly, the four kinds of linear relationship with the apparent rate constant were seen in both the inner diameter of TNAs and the length. Consequently, the apparent rate constant strongly depended on inner diameter of TNAs.

  7. Tunable finite-sized chains to control magnetic relaxation

    Science.gov (United States)

    Ekstrand, Paul D.; Javier, Daniel J.; Gredig, Thomas

    2017-01-01

    The magnetic dynamics of low-dimensional iron ion chains have been studied with regards to the tunable finite-sized chain length using iron phthalocyanine thin films. The deposition temperature varies the diffusion length during thin-film growth by limiting the average crystal size in the range from 40 to 110 nm . Using a method common for single chain magnets, the magnetic relaxation time for each chain length is determined from temporal remanence data and fit to a stretched exponential form in the temperature range below 5 K , the onset for magnetic hysteresis. A temperature-independent master curve is generated by scaling the remanence by its relaxation time to fit the energy barrier for spin reversal, and the single spin-relaxation time. The energy barrier of 95 K is found to be independent of the chain length. In contrast, the single spin-relaxation time increases with longer chains from under 1 ps to 800 ps. We show that thin films provide the nanoarchitecture to control magnetic relaxation and a testbed to study finite-size effects in low-dimensional magnetic systems.

  8. Signalling and the control of skeletal muscle size

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Anthony [School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights Campus, Reading, Berkshire, RG6 6UB (United Kingdom); Patel, Ketan, E-mail: ketan.patel@reading.ac.uk [School of Biological Sciences, Hopkins Building, University of Reading, Whiteknights Campus, Reading, Berkshire, RG6 6UB (United Kingdom)

    2010-11-01

    Skeletal muscle is highly adaptive to environmental stimuli and can alter its mass accordingly. This tissue is almost unique in that it can increase its size through two distinct mechanisms. It can grow through a cellular process mediated by cell fusion, or it can increase its size simply by increasing its protein content. Understanding how these processes are regulated is crucial for the development of potential therapies against debilitating skeletal muscle wasting diseases. Two key signalling molecules, Insulin like Growth Factor (IGF) and GDF-8/myostatin, have emerged in recent years to be potent regulators of skeletal muscle size. In this review we bring together recent data highlighting the important and novel aspects of both molecules and their signalling pathways, culminating in a discussion of the cellular and tissue phenotypic outcomes of their stimulation or antagonism. We emphasise the complex regulatory mechanisms and discuss the temporal and spatial differences that control their action, understanding of which is crucial to further their use as potential therapeutic targets.

  9. Hydrophilic and size-controlled graphene nanopores for protein detection

    Science.gov (United States)

    Goyal, Gaurav; Bok Lee, Yong; Darvish, Armin; Ahn, Chi Won; Kim, Min Jun

    2016-12-01

    This paper describes a general approach for transferring clean single-layer graphene onto silicon nitride nanopore devices and the use of the electron beam of a transmission electron microscope (TEM) to drill size-controlled nanopores in freely suspended graphene. Besides nanopore drilling, we also used the TEM to heal and completely close the unwanted secondary holes formed by electron beam damage during the drilling process. We demonstrate electron beam assisted shrinking of irregularly shaped 40-60 nm pores down to 2 nm, exhibiting an exquisite control of graphene nanopore diameter. Our fabrication workflow also rendered graphene nanopores hydrophilic, allowing easy wetting and use of the pores for studying protein translocation and protein-protein interaction with a high signal to noise ratio.

  10. Surfactant effects in magnetite nanoparticles of controlled size

    Energy Technology Data Exchange (ETDEWEB)

    Guardia, P. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia (IN2UB) , Universitat de Barcelona, Marti i Franques 1, 08028- Barcelona, Catalonia (Spain); Batlle-Brugal, B. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia (IN2UB) , Universitat de Barcelona, Marti i Franques 1, 08028- Barcelona, Catalonia (Spain); Roca, A.G. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, Cantoblanco 28049, Madrid (Spain); Iglesias, O. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia (IN2UB) , Universitat de Barcelona, Marti i Franques 1, 08028- Barcelona, Catalonia (Spain); Morales, M.P. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, Cantoblanco 28049, Madrid (Spain); Serna, C.J. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, Cantoblanco 28049, Madrid (Spain); Labarta, A. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia (IN2UB) , Universitat de Barcelona, Marti i Franques 1, 08028- Barcelona, Catalonia (Spain); Batlle, X. [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia (IN2UB) , Universitat de Barcelona, Marti i Franques 1, 08028- Barcelona, Catalonia (Spain)]. E-mail: xavier@ffn.ub.es

    2007-09-15

    Magnetite Fe{sub 3}O{sub 4} nanoparticles of controlled size within 6 and 20 nm in diameter were synthesised by thermal decomposition of an iron organic precursor in an organic medium. Particles were coated with oleic acid. For all samples studied, saturation magnetisation M{sub s} is size-independent, and reaches a value close to that expected for bulk magnetite, in contrast to results in small particle systems for which M{sub s} is usually much smaller due to surface spin disorder. The coercive field for the 6 nm particles is in agreement with coherent rotation, taking the bulk magnetocrystalline anisotropy into account. Both results suggest that the oleic acid molecules covalently bonded to the nanoparticle surface yield a strong reduction in the surface spin disorder. However, although the saturated state may be similar, the approach to saturation is different and, in particular, the high-field differential susceptibility is one order of magnitude larger than in bulk materials. The relevance of these results in biomedical applications is discussed.

  11. The influence of school culture on smoking among pupils.

    Science.gov (United States)

    Aveyard, Paul; Markham, Wolfgang A; Lancashire, Emma; Bullock, Alison; Macarthur, Christine; Cheng, K K; Daniels, Harry

    2004-05-01

    School factors and not solely pupil composition probably cause variation in smoking prevalence amongst schools, but there are no theoretical models to explain why. In this paper we propose a hypothesis to explain schools' influence on pupils' smoking and test this using an existing cross-sectional survey of 23,282 pupils from 166 secondary schools in the West Midlands, UK. We hypothesise that school-level educational achievement scores would not be associated with smoking prevalence, but schools providing value-added education given the social background of pupils (authoritative schools) would provide effective support and control, have a relatively strong influence on pupils' lives and be associated with lower than average smoking prevalence. Schools providing value-denuded education (laissez-faire schools) would have a relatively weak influence on pupils' lives and be associated with higher than average smoking prevalence. The school achievement measures were the proportion of pupils achieving 5A-C General Certificates of Secondary Education (5A-Cs) grades and the proportion of half days lost to truancy. Value-added/denuded terms were created by regressing 5A-Cs and truancy on five markers of the social profile of pupils at the school. Authoritative schools achieved better than expected rates on both measures. Laissez-faire schools achieved worse than expected rates on both measures. All other schools were classed as indeterminate. Multilevel logistic regression was used to relate the risk of regular smoking to school culture in both achievement and authoritative/laissez-faire terms, both with and without adjustment for pupil-level risk factors for smoking. As predicted, schools' achievement measures were unrelated to pupils' smoking. The odds ratios (95% confidence intervals) for smoking in authoritative and laissez-faire schools relative to indeterminate schools were 0.80 (0.70-0.91) and 1.16 (1.07-1.27), respectively. Adjustment for pupil-level smoking risk

  12. MyosinV controls PTEN function and neuronal cell size.

    Science.gov (United States)

    van Diepen, Michiel T; Parsons, Maddy; Downes, C Peter; Leslie, Nicholas R; Hindges, Robert; Eickholt, Britta J

    2009-10-01

    The tumour suppressor PTEN can inhibit cell proliferation and migration as well as control cell growth, in different cell types. PTEN functions predominately as a lipid phosphatase, converting PtdIns(3,4,5)P(3) to PtdIns(4,5)P(2), thereby antagonizing PI(3)K (phosphoinositide 3-kinase) and its established downstream effector pathways. However, much is unclear concerning the mechanisms that regulate PTEN movement to the cell membrane, which is necessary for its activity towards PtdIns(3,4,5)P(3) (Refs 3, 4, 5). Here we show a requirement for functional motor proteins in the control of PI3K signalling, involving a previously unknown association between PTEN and myosinV. FRET (Förster resonance energy transfer) measurements revealed that PTEN interacts directly with myosinV, which is dependent on PTEN phosphorylation mediated by CK2 and/or GSK3. Inactivation of myosinV-transport function in neurons increased cell size, which, in line with known attributes of PTEN-loss, required PI(3)K and mTor. Our data demonstrate a myosin-based transport mechanism that regulates PTEN function, providing new insights into the signalling networks regulating cell growth.

  13. Speckle imaging through turbulent atmosphere based on adaptable pupil segmentation.

    Science.gov (United States)

    Loktev, Mikhail; Soloviev, Oleg; Savenko, Svyatoslav; Vdovin, Gleb

    2011-07-15

    We report on the first results to our knowledge obtained with adaptable multiaperture imaging through turbulence on a horizontal atmospheric path. We show that the resolution can be improved by adaptively matching the size of the subaperture to the characteristic size of the turbulence. Further improvement is achieved by the deconvolution of a number of subimages registered simultaneously through multiple subapertures. Different implementations of multiaperture geometry, including pupil multiplication, pupil image sampling, and a plenoptic telescope, are considered. Resolution improvement has been demonstrated on a ∼550 m horizontal turbulent path, using a combination of aperture sampling, speckle image processing, and, optionally, frame selection. © 2011 Optical Society of America

  14. Size-controlled and redox-responsive supramolecular nanoparticles

    Directory of Open Access Journals (Sweden)

    Raquel Mejia-Ariza

    2015-12-01

    Full Text Available Control over the assembly and disassembly of nanoparticles is pivotal for their use as drug delivery vehicles. Here, we aim to form supramolecular nanoparticles (SNPs by combining advantages of the reversible assembly properties of SNPs using host–guest interactions and of a stimulus-responsive moiety. The SNPs are composed of a core of positively charged poly(ethylene imine grafted with β-cyclodextrin (CD and a positively charged ferrocene (Fc-terminated poly(amidoamine dendrimer, with a monovalent stabilizer at the surface. Fc was chosen for its loss of CD-binding properties when oxidizing it to the ferrocenium cation. The ionic strength was shown to play an important role in controlling the aggregate growth. The attractive supramolecular and repulsive electrostatic interactions constitute a balance of forces in this system at low ionic strengths. At higher ionic strengths, the increased charge screening led to a loss of electrostatic repulsion and therefore to faster aggregate growth. A Job plot showed that a 1:1 stoichiometry of host and guest moieties gave the most efficient aggregate growth. Different stabilizers were used to find the optimal stopper to limit the growth. A weaker guest moiety was shown to be less efficient in stabilizing the SNPs. Also steric repulsion is important for achieving SNP stability. SNPs of controlled particle size and good stability (up to seven days were prepared by fine-tuning the ratio of multivalent and monovalent interactions. Finally, reversibility of the SNPs was confirmed by oxidizing the Fc guest moieties in the core of the SNPs.

  15. Size-controlled and redox-responsive supramolecular nanoparticles.

    Science.gov (United States)

    Mejia-Ariza, Raquel; Kronig, Gavin A; Huskens, Jurriaan

    2015-01-01

    Control over the assembly and disassembly of nanoparticles is pivotal for their use as drug delivery vehicles. Here, we aim to form supramolecular nanoparticles (SNPs) by combining advantages of the reversible assembly properties of SNPs using host-guest interactions and of a stimulus-responsive moiety. The SNPs are composed of a core of positively charged poly(ethylene imine) grafted with β-cyclodextrin (CD) and a positively charged ferrocene (Fc)-terminated poly(amidoamine) dendrimer, with a monovalent stabilizer at the surface. Fc was chosen for its loss of CD-binding properties when oxidizing it to the ferrocenium cation. The ionic strength was shown to play an important role in controlling the aggregate growth. The attractive supramolecular and repulsive electrostatic interactions constitute a balance of forces in this system at low ionic strengths. At higher ionic strengths, the increased charge screening led to a loss of electrostatic repulsion and therefore to faster aggregate growth. A Job plot showed that a 1:1 stoichiometry of host and guest moieties gave the most efficient aggregate growth. Different stabilizers were used to find the optimal stopper to limit the growth. A weaker guest moiety was shown to be less efficient in stabilizing the SNPs. Also steric repulsion is important for achieving SNP stability. SNPs of controlled particle size and good stability (up to seven days) were prepared by fine-tuning the ratio of multivalent and monovalent interactions. Finally, reversibility of the SNPs was confirmed by oxidizing the Fc guest moieties in the core of the SNPs.

  16. [Tonic pupil caused by ischemia].

    Science.gov (United States)

    Wilhelm, H

    1989-01-01

    Tonic pupil is usually an idiopathic condition. In some cases, the cause of the ciliary ganglion lesion leading to tonic pupils is obvious. Rarely ischemia causes a lesion of the ciliary ganglion or the short ciliary nerves due to the good blood supply of the ciliary ganglion. Only two cases of tonic pupils in the course of giant cell arteritis are mentioned in the literature, but tonic pupils are probably much more common with this disease. Five cases are demonstrated here. All had associated ischemic optic neuropathy, and stagnation of the blood flow in the supratrochlear artery could be demonstrated in two cases by Doppler sonography. Tonic pupils may also occur when an oclusion of the internal carotid artery resolves, probably because of transient stasis of the orbital blood flow. In another case, tonic pupils were associated with choroidal ischemia (proved by video fluorescent angiography) of unknown origin. The diagnosis of tonic pupils was made by pharmacological testing for cholinergic hypersensitivity with 0.1% pilocarpine.

  17. Pupils have rights too

    Directory of Open Access Journals (Sweden)

    Banjanin-Đuričić Nada

    2010-01-01

    Full Text Available The text points out the delicate problem of inadequate treatment of pupils by teachers. Such treatment may include insults, verbal aggression, sarcasm, but also the double meaning of the message in which it is hard to prove violation of pupils’ personality. Although characteristics of desirable relationship of teachers toward children are specified by the Convention on the Rights of the Child, Law on Foundations of the Education and Upbringing System, as well as by the Protocol for Protection of Children and Students from Violence, Abuse and Neglect in Educational Institutions, verbal aggression is still present, but often unrecognized as a form of violation of pupils’ rights - right to respect of personality and right to development. The text describes an attempt, almost an experiment, in the form of workshop model that can contribute to recognition of this problem and help in finding constructive ways to overcome it.

  18. Pupil geometry and pupil re-imaging in telescope arrays

    Science.gov (United States)

    Traub, Wesley A.

    1990-01-01

    This paper considers the issues of lateral and longitudinal pupil geometry in ground-based telescope arrays, such as IOTA. In particular, it is considered whether or not pupil re-imaging is required before beam combination. By considering the paths of rays through the system, an expression is derived for the optical path errors in the combined wavefront as a function of array dimensions, telescope magnification factor, viewing angle, and field-of-view. By examining this expression for the two cases of pupil-plane and image-plane combination, operational limits can be found for any array. As a particular example, it is shown that for IOTA no pupil re-imaging optics will be needed.

  19. Correcting for the effects of pupil discontinuities with the ACAD method

    Science.gov (United States)

    Mazoyer, Johan; Pueyo, Laurent; N'Diaye, Mamadou; Mawet, Dimitri; Soummer, Rémi; Norman, Colin

    2016-07-01

    The current generation of ground-based coronagraphic instruments uses deformable mirrors to correct for phase errors and to improve contrast levels at small angular separations. Improving these techniques, several space and ground based instruments are currently developed using two deformable mirrors to correct for both phase and amplitude errors. However, as wavefront control techniques improve, more complex telescope pupil geometries (support structures, segmentation) will soon be a limiting factor for these next generation coronagraphic instruments. The technique presented in this proceeding, the Active Correction of Aperture Discontinuities method, is taking advantage of the fact that most future coronagraphic instruments will include two deformable mirrors, and is proposing to find the shapes and actuator movements to correct for the effect introduced by these complex pupil geometries. For any coronagraph previously designed for continuous apertures, this technique allow to obtain similar performance in contrast with a complex aperture (with segmented and secondary mirror support structures), with high throughput and flexibility to adapt to changing pupil geometry (e.g. in case of segment failure or maintenance of the segments). We here present the results of the parametric analysis realized on the WFIRST pupil for which we obtained high contrast levels with several deformable mirror setups (size, separation between them), coronagraphs (Vortex charge 2, vortex charge 4, APLC) and spectral bandwidths. However, because contrast levels and separation are not the only metrics to maximize the scientific return of an instrument, we also included in this study the influence of these deformable mirror shapes on the throughput of the instrument and sensitivity to pointing jitters. Finally, we present results obtained on another potential space based telescope segmented aperture. The main result of this proceeding is that we now obtain comparable performance than the

  20. size control. Disorders of the pathway in cancer diseases

    Directory of Open Access Journals (Sweden)

    Agnieszka Rybarczyk

    2014-05-01

    Full Text Available The Hippo pathway (also known as SWH – Salvador/Warts/Hippo, discovered for the first time in Drosophila melanogaster, is responsible for cell proliferation and organ size control in mammalian systems. The components of the pathway are two kinases and their adaptor proteins which inhibit the transcription co-activator YAP by phosphorylation. When the pathway is inactive (as an effect of upstream component gene expression disorders, activated YAP is translocated to the nucleus where it cooperates with TEAD transcription factor and promotes expression of genes that regulate cell proliferation and apoptosis. YAP acts generally as an oncogene, although there are some reports describing its role as a tumor suppressor. Since all of the core components are well known, the latest reports provide mostly information about upstream components of the Hippo pathway or its interaction with other biochemical pathways. Because of the Hippo pathway’s role in the cell cycle, it has become a very attractive object for studies of the genetic background of cancer. The under- or overexpression of genes involved in the Hippo pathway has been described in many different types of cancers. Moreover, it has been shown that there is a strong connection between cancer cell phenotype and highly activated YAP presence in the nucleus. This paper reviews the most important data about Hippo pathway regulation in Drosophila and mammals, including its numerous disorders and their implications for cell function.

  1. Size controlled preparation of CdTe nanoparticles by apoferritin

    Science.gov (United States)

    Peng, Shasha; Kim, Ji Hyeon; Park, Sang Joon

    2017-06-01

    Cadmium telluride quantum dots (CdTe QDs) were synthesized in the cavity of horse spleen apoferritin and CdTe-apoferritin complex was fluorescent. Apoferritin is a popular bio-template to prepare various nanoparticles with narrow size distribution due to the confinement of the hollow protein shell. In this work, we controlled the diameters of CdTe NPs by changing the reaction conditions. Altering the molar ratio of Cd to Te from 1:0.05 to 1:0.2 and pH can change the diameters of NPs cores. The synthesized QDs were characterized by photoluminescence (PL) spectroscopy, UV-vis spectroscopy and transmission electron microscopy (TEM). The results showed that the PL intensity decreased when the Cd/Te molar ratio was decreased from 1:0.05 to 1:0.3 and pH was increased from 9.01 to 9.96. In addition, it was proven that the existence of apoferritin is necessary for the present synthetic method and the formation of CdTe QDs in the inner cavity of apoferritin.

  2. Infant and adult pupil dilation in response to unexpected sounds.

    Science.gov (United States)

    Wetzel, Nicole; Buttelmann, David; Schieler, Andy; Widmann, Andreas

    2016-04-01

    Surprisingly occurring sounds outside the focus of attention can involuntarily capture attention. This study focuses on the impact of deviant sounds on the pupil size as a marker of auditory involuntary attention in infants. We presented an oddball paradigm including four types of deviant sounds within a sequence of repeated standard sounds to 14-month-old infants and to adults. Environmental and noise deviant sounds elicited a strong pupil dilation response (PDR) in both age groups. In contrast, moderate frequency deviants elicited a significant PDR in adults only. Moreover, a principal component analysis revealed two components underlying the PDR. Component scores differ, depending on deviant types, between age groups. Results indicate age effects of parasympathetic inhibition and sympathetic activation of the pupil size caused by deviant sounds with a high arousing potential. Results demonstrate that the PDR is a sensitive tool for the investigation of involuntary attention to sounds in preverbal children.

  3. Body size perception and weight control in youth

    DEFF Research Database (Denmark)

    Quick, V; Nansel, T R; Liu, D

    2014-01-01

    OBJECTIVES: To examine 9-year trends and relationships regarding misperceptions of body size and dieting for weight loss among adolescents from 24 countries, and explore the influence of country-level overweight prevalence. METHODS: Sociodemographic characteristics, body size perception and dieti......, suggesting a potentially stronger impact of social comparison on weight-related perceptions than on behavior.......OBJECTIVES: To examine 9-year trends and relationships regarding misperceptions of body size and dieting for weight loss among adolescents from 24 countries, and explore the influence of country-level overweight prevalence. METHODS: Sociodemographic characteristics, body size perception and dieting......, underestimation of body size in overweight adolescents, dieting for weight loss in non-overweight and overweight adolescents and relationships between body size perception and dieting. Analyses were stratified by weight status and sex. Covariates included country-level overweight prevalence, family affluence...

  4. What factors control the size of an eruption?

    Science.gov (United States)

    Gudmundsson, Agust

    2017-04-01

    For human society, eruption sizes (eruptive volumes or masses) are of the greatest concern. In particular, the largest eruptions, producing volumes of the order of hundreds or thousands of cubic kilometres, provide, together with meteoritic impacts, the greatest natural threats to mankind. Eruptive volumes tend to follow power laws so that most eruptions are comparatively small whereas a few are very large. It follows that a while during most ruptures of the source chambers a small fraction of the magma leaves the chamber, in some ruptures a very large fraction of the magma leaves the chamber. Most explosive eruptions larger than about 25 km3 are associated with caldera collapse. In the standard 'underpressure' ('lack of magmatic support') model, however, the collapse is the consequence, not the cause, of the large eruption. For poroelastic models, typically less than 4% of the magma in a felsic chamber and less than 0.1% of the magma in a mafic chamber leaves the chamber during rupture (and eventual eruption). In some caldera models, however, 20-70% of the magma is supposed to leave the chamber before the ring-fault forms and the caldera block begins to subside. In these models any amount of magma can flow out of the chamber following its rupture and there is apparently no way to forecast either the volume of magma injected from the chamber (hence the potential size of an eventual eruption) or the conditions for caldera collapse. An alternative model is proposed here. In this model normal (small) eruptions are controlled by standard poroelastity behaviour of the chamber, whereas large eruptions are controlled by chamber-volume reduction or shrinkage primarily through caldera/graben block subsidence into the chamber. Volcanotectonic stresses are then a major cause of ring-fault/graben boundary-fault formation. When large slips occur on these faults, the subsiding crustal block reduces the volume of the underlying chamber/reservoir, thereby maintaining its excess

  5. Size-Dependent Expression of the Mitotic Activator Cdc25 Suggests a Mechanism of Size Control in Fission Yeast.

    Science.gov (United States)

    Keifenheim, Daniel; Sun, Xi-Ming; D'Souza, Edridge; Ohira, Makoto J; Magner, Mira; Mayhew, Michael B; Marguerat, Samuel; Rhind, Nicholas

    2017-05-22

    Proper cell size is essential for cellular function. Nonetheless, despite more than 100 years of work on the subject, the mechanisms that maintain cell-size homeostasis are largely mysterious [1]. Cells in growing populations maintain cell size within a narrow range by coordinating growth and division. Bacterial and eukaryotic cells both demonstrate homeostatic size control, which maintains population-level variation in cell size within a certain range and returns the population average to that range if it is perturbed [1, 2]. Recent work has proposed two different strategies for size control: budding yeast has been proposed to use an inhibitor-dilution strategy to regulate size at the G1/S transition [3], whereas bacteria appear to use an adder strategy, in which a fixed amount of growth each generation causes cell size to converge on a stable average [4-6]. Here we present evidence that cell size in the fission yeast Schizosaccharomyces pombe is regulated by a third strategy: the size-dependent expression of the mitotic activator Cdc25. cdc25 transcript levels are regulated such that smaller cells express less Cdc25 and larger cells express more Cdc25, creating an increasing concentration of Cdc25 as cells grow and providing a mechanism for cells to trigger cell division when they reach a threshold concentration of Cdc25. Because regulation of mitotic entry by Cdc25 is well conserved, this mechanism may provide a widespread solution to the problem of size control in eukaryotes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Teaching Styles and Pupil Progress

    Science.gov (United States)

    Rogers, Vincent; Baron, Joan

    1977-01-01

    Critically analyzes Neville Bennett's book "Teaching Styles and Pupil Progress," which found that formal teaching styles are more closely associated with student achievement in "basic skills" than are informal styles. (IRT)

  7. Pupil-linked arousal determines variability in perceptual decision making.

    Science.gov (United States)

    Murphy, Peter R; Vandekerckhove, Joachim; Nieuwenhuis, Sander

    2014-09-01

    Decision making between several alternatives is thought to involve the gradual accumulation of evidence in favor of each available choice. This process is profoundly variable even for nominally identical stimuli, yet the neuro-cognitive substrates that determine the magnitude of this variability are poorly understood. Here, we demonstrate that arousal state is a powerful determinant of variability in perceptual decision making. We measured pupil size, a highly sensitive index of arousal, while human subjects performed a motion-discrimination task, and decomposed task behavior into latent decision making parameters using an established computational model of the decision process. In direct contrast to previous theoretical accounts specifying a role for arousal in several discrete aspects of decision making, we found that pupil diameter was uniquely related to a model parameter representing variability in the rate of decision evidence accumulation: Periods of increased pupil size, reflecting heightened arousal, were characterized by greater variability in accumulation rate. Pupil diameter also correlated trial-by-trial with specific patterns of behavior that collectively are diagnostic of changing accumulation rate variability, and explained substantial individual differences in this computational quantity. These findings provide a uniquely clear account of how arousal state impacts decision making, and may point to a relationship between pupil-linked neuromodulation and behavioral variability. They also pave the way for future studies aimed at augmenting the precision with which people make decisions.

  8. A Total Quality-Control Plan with Right-Sized Statistical Quality-Control.

    Science.gov (United States)

    Westgard, James O

    2017-03-01

    A new Clinical Laboratory Improvement Amendments option for risk-based quality-control (QC) plans became effective in January, 2016. Called an Individualized QC Plan, this option requires the laboratory to perform a risk assessment, develop a QC plan, and implement a QC program to monitor ongoing performance of the QC plan. Difficulties in performing a risk assessment may limit validity of an Individualized QC Plan. A better alternative is to develop a Total QC Plan including a right-sized statistical QC procedure to detect medically important errors. Westgard Sigma Rules provides a simple way to select the right control rules and the right number of control measurements.

  9. RNA Control of HIV-1 Particle Size Polydispersity

    CERN Document Server

    Faivre-Moskalenko, Cendrine; Thomas, Audrey; Tartour, Kevin; Beck, Yvonne; Iazykov, Maksym; Danial, John; Lourdin, Morgane; Muriaux, Delphine; Castelnovo, Martin

    2014-01-01

    HIV-1, an enveloped RNA virus, produces viral particles that are known to be much more heterogeneous in size than is typical of non-enveloped viruses. We present here a novel strategy to study HIV-1 Viral Like Particles (VLP) assembly by measuring the size distribution of these purified VLPs and subsequent viral cores thanks to Atomic Force Microscopy imaging and statistical analysis. This strategy allowed us to identify whether the presence of viral RNA acts as a modulator for VLPs and cores size heterogeneity in a large population of particles. These results are analyzed in the light of a recently proposed statistical physics model for the self-assembly process. In particular, our results reveal that the modulation of size distribution by the presence of viral RNA is qualitatively reproduced, suggesting therefore an entropic origin for the modulation of RNA uptake by the nascent VLP.

  10. Studies on the particle size control of gelatin microspheres

    Institute of Scientific and Technical Information of China (English)

    Ruixue SUN; Jingjing SHI; Yanchuan GUO; Lijuan CHEN

    2009-01-01

    A series of gelatin microspheres (GMs) were prepared through emulsification-coacervation method in water-in-oil (w/o) emulsions. The influence of preparation parameters on particle size, surface morphology, and dispersion of GMs was examined. The studied preparation parameters include concentration of gelatin solutions, concentration of the emulsifier, w/o ratio, emulsifying time, stirring speed, and so on. The surface morphology, dispersion, and particle sizes of GMs were determined by the scanning electron microscopy (SEM), SemAfore 4 Demo software, and particle size distribution graphic charts. The experimental results indicated that increasing the concentration of gelatin solution would increase the particle size of GMs. When the solution concentration increased from 0.050 to 0.200 g/mL gradually, the particle size increased correspondingly. The relationship between the two quantities was linear. On the contrary, increasing the concentration of the emulsifier would decrease the particle size of GMs. Furthermore, the particle size reduced quickly at initial time and slowed down latterly. With the increase of emulsifier concentration from 0 to 0.020 g/mL, the mean diameters of GMs decreased from 17.32 to 5.38 urn. However, the particle size dwindled slowly when emulsifier concentration was higher than 0.020 g/mL. The excellent result was obtained with the condition of 0.050 g/mL of emulsifier concentration, 0.100 g/mL of gelatin solution concentration, 1/5 of w/o ratio, 10 min of emulsifying time, and 900 r/min of the stirring speed. The GMs prepared at this condition had the smallest sizes, the narrowest size distribution, the best spherical shape, and fluidity. The w/o ratio has the same influence on particle size of GMs as that of gelatin solution concentration. With the increase of w/o ratio, the average particle sizes increased linearly, and the surface of microspheres become smoother as well. It is supposed that w/o ratio can be used to change the diameters

  11. Size-Controlled Dissolution of Organic-Coated Silver Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui; Levard, Clément; Marinakos, Stella M.; Cheng, Yingwen; Liu, Jie; Michel, F. Marc; Brown, Jr., Gordon E.; Lowry, Gregory V. (Duke)

    2012-04-02

    The solubility of Ag NPs can affect their toxicity and persistence in the environment. We measured the solubility of organic-coated silver nanoparticles (Ag NPs) having particle diameters ranging from 5 to 80 nm that were synthesized using various methods, and with different organic polymer coatings including poly(vinylpyrrolidone) and gum arabic. The size and morphology of Ag NPs were characterized by transmission electron microscopy (TEM). X-ray absorption fine structure (XAFS) spectroscopy and synchrotron-based total X-ray scattering and pair distribution function (PDF) analysis were used to determine the local structure around Ag and evaluate changes in crystal lattice parameters and structure as a function of NP size. Ag NP solubility dispersed in 1 mM NaHCO{sub 3} at pH 8 was found to be well correlated with particle size based on the distribution of measured TEM sizes as predicted by the modified Kelvin equation. Solubility of Ag NPs was not affected by the synthesis method and coating as much as by their size. Based on the modified Kelvin equation, the surface tension of Ag NPs was found to be {approx}1 J/m{sup 2}, which is expected for bulk fcc (face centered cubic) silver. Analysis of XAFS, X-ray scattering, and PDFs confirm that the lattice parameter, {alpha}, of the fcc crystal structure of Ag NPs did not change with particle size for Ag NPs as small as 6 nm, indicating the absence of lattice strain. These results are consistent with the finding that Ag NP solubility can be estimated based on TEM-derived particle size using the modified Kelvin equation for particles in the size range of 5-40 nm in diameter.

  12. Size-controlled magnetic nanoparticles with lecithin for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.I. [Department of Materials Science and Engineering, Chungnam National University, 305-764 Daejeon (Korea, Republic of); Kim, J.H. [Research Center for Advanced Magnetic Materials, Chungnam National University, 305-764 Daejeon (Korea, Republic of); Kim, C.G. [Department of Materials Science and Engineering, Chungnam National University, 305-764 Daejeon (Korea, Republic of); Kim, C.O. [Department of Materials Science and Engineering, Chungnam National University, 305-764 Daejeon (Korea, Republic of)]. E-mail: magkim@cnu.ac.kr

    2007-05-15

    Lecithin-adsorbed magnetic nanoparticles were prepared by three-step process that the thermal decomposition was combined with ultrasonication. Experimental parameters were three items-molar ratio between Fe(CO){sub 5} and oleic acid, keeping time at decomposition temperature and lecithin concentration. As the molar ratio between Fe(CO){sub 5} and oleic acid, and keeping time at decomposition temperature increased, the particle size increased. However, the change of lecithin concentration did not show the remarkable particle size variation.

  13. Size-controlled dissolution of organic-coated silver nanoparticles.

    Science.gov (United States)

    Ma, Rui; Levard, Clément; Marinakos, Stella M; Cheng, Yingwen; Liu, Jie; Michel, F Marc; Brown, Gordon E; Lowry, Gregory V

    2012-01-17

    The solubility of Ag NPs can affect their toxicity and persistence in the environment. We measured the solubility of organic-coated silver nanoparticles (Ag NPs) having particle diameters ranging from 5 to 80 nm that were synthesized using various methods, and with different organic polymer coatings including poly(vinylpyrrolidone) and gum arabic. The size and morphology of Ag NPs were characterized by transmission electron microscopy (TEM). X-ray absorption fine structure (XAFS) spectroscopy and synchrotron-based total X-ray scattering and pair distribution function (PDF) analysis were used to determine the local structure around Ag and evaluate changes in crystal lattice parameters and structure as a function of NP size. Ag NP solubility dispersed in 1 mM NaHCO(3) at pH 8 was found to be well correlated with particle size based on the distribution of measured TEM sizes as predicted by the modified Kelvin equation. Solubility of Ag NPs was not affected by the synthesis method and coating as much as by their size. Based on the modified Kelvin equation, the surface tension of Ag NPs was found to be ∼1 J/m(2), which is expected for bulk fcc (face centered cubic) silver. Analysis of XAFS, X-ray scattering, and PDFs confirm that the lattice parameter, a, of the fcc crystal structure of Ag NPs did not change with particle size for Ag NPs as small as 6 nm, indicating the absence of lattice strain. These results are consistent with the finding that Ag NP solubility can be estimated based on TEM-derived particle size using the modified Kelvin equation for particles in the size range of 5-40 nm in diameter.

  14. What Controls the Size of the Antarctic Ozone Hole?

    Science.gov (United States)

    Bhartia, P. K. (Technical Monitor); Newman, Paul A.; Kawa, S. Randolph; Nash, Eric R.

    2002-01-01

    The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million square kilometers. In the 8-year period from 1981 to 1989, the area expanded by 18 Million square kilometers. During the last 5 years, the hole has been observed to exceed 25 Million square kilometers over brief periods. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre- 1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

  15. Image Analysis of Pellet Size for a Control System in Industrial Feed Production

    DEFF Research Database (Denmark)

    Ljungqvist, Martin Georg; Nielsen, Michael Engelbrecht; Ersbøll, Bjarne Kjær

    2011-01-01

    When producing aquaculture fish feed pellets, the size of the output product is of immense importance. As the production method cannot produce pellets of constant and uniform size using constant machine settings, there is a demand for size control. Fish fed with feed pellets of improper size...

  16. Internet usage of fourth-grader primary school pupils

    Directory of Open Access Journals (Sweden)

    Peter Kristof Nagy

    2014-08-01

    Full Text Available The development of information and communication technologies has resulted in revolutionary changes, which seem to continue in economy, society and many areas of life. The most important resource of the new social structure emerging as a result of technologies is information, thus the development of human capacity related to the use of information is extremely important. It may not be easy for parents and teachers to face the fact that the majority of their children/pupils know more about cyberspace than themselves. But are primary school pupils really better versed? Does digital literacy indeed automatically evolve? Does the use of the internet by all means improve children’s academic performance? In our current study we are researching how primary school pupils in the easternmost part of Hungary use the internet, and what effects it has on their studies. We would also like to emphasize the role of teachers working at the lower grades of the primary school in the formation of pupils’ digital literacy. In 2013 190 fourth-grader primary school pupils of eight schools filled in our questionnaire. Based on the data negative correlation was found between the time spent on web browsing and the academic average. Analysis of variance also revealed that those pupils have a higher academic average whose parents regularly check the purpose of their children’s internet usage. Our research results showed that the pupils who use the internet and the library equally to search for new information have a higher academic average compared to those pupils who only make use of either the traditional or the online option only. The most important result of the research is that in the case of adequate parental or professional (teacher control internet may have fruitful effects on pupils’ studies, but in the lack of such control the opposite is more likely.

  17. Synthesis of size-controlled Bi particles by electrochemical deposition

    Indian Academy of Sciences (India)

    C N Tharamani; H C Thejaswini; S Sampath

    2008-06-01

    Small sized bismuth particles are prepared by an electrochemical method using a triple voltage pulse technique. The bath composition and electrochemical parameters are optimized to yield monodisperse particles. The particles have been characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, UV-visible spectroscopy and X-ray diffraction technique. The particles, as deposited, are highly crystalline in nature and the particle size and shape get tuned depending on the conditions of deposition.

  18. Pupil-Linked Arousal Determines Variability in Perceptual Decision Making: e1003854

    National Research Council Canada - National Science Library

    Peter R Murphy; Joachim Vandekerckhove; Sander Nieuwenhuis

    2014-01-01

    .... We measured pupil size, a highly sensitive index of arousal, while human subjects performed a motion-discrimination task, and decomposed task behavior into latent decision making parameters using...

  19. Biotemplated fabrication of size controlled palladium nanoparticle chains

    NARCIS (Netherlands)

    Zhou, Xingfei; Zheng, Lifei; Li, Rong; Li, Bin; Pillai, Saju; Xu, Peng; Zhang, Yi

    2012-01-01

    Metal nanoparticles exhibit unique size- and spatial organization-dependent physical and chemical properties, and have a wide range of applications in various areas including single electron devices, chemical catalysts and biomedicines. In this paper, chains of palladium nanoparticles were obtained

  20. Reversible Size Control of Silver Nanoclusters via Ligand-exchange

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2015-05-21

    The properties of atomically monodisperse noble metal nanoclusters (NCs) are intricately intertwined with their precise molecular formula. The vast majority of size-specific NC syntheses start from the reduction of the metal salt and thiol ligand mixture. Only in gold was it recently shown that ligand-exchange could induce the growth of NCs from one atomically precise species to another; a process of yet unknown reversibility. Here, we present a process for the ligand-exchange-induced growth of atomically precise silver NCs, in a biphasic liquid-liquid system, which is particularly of interest because of its complete reversibility and ability to occur at room temperature. We explore this phenomenon in-depth using Ag35(SG)18 [SG= glutathionate] and Ag44(4-FTP)30 [4-FTP= 4-fluorothiophenol] as model systems. We show that the ligand-exchange conversion of Ag35(SG)18 into Ag44(4-FTP)30 is rapid (< 5 min) and direct, while the reverse process proceeds slowly through intermediate cluster sizes. We adapt a recently developed theory of reverse Ostwald ripening to model the NCs’ interconvertibility. The model’s predictions are in good agreement with the experimental observations, and they highlight the importance of small changes in the ligand-metal binding energy in determining the final equilibrium NC size. Based on the insight provided by this model, we demonstrated experimentally that by varying the choice of ligands, ligand-exchange can be used to obtain different sized NCs. The findings in this work establish ligand-exchange as a versatile tool for tuning cluster sizes.

  1. Size-controllable polypyrrole nanospheres synthesized in the presence of phosphorylated chitosan and their size effect in different applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Cao, Yi; Lu, Yun, E-mail: yunlu@nju.edu.cn [Nanjing University, Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, School of Chemistry and Chemical Engineering (China)

    2015-05-15

    The size-controllable polypyrrole (PPy) nanospheres are successfully synthesized by oxidative polymerization of pyrrole using N-methylene phosphonic chitosan (NMPC) as a structure-directing agent. By simply changing the amount of NMPC, the size of the PPy nanospheres can be adjusted from 190 to 50 nm in diameter. The spectrometric results suggest that the electrostatic interactions of phosphate groups in NMPC molecule with pyrrole ring might be a driving force for formation of the uniform and size-controllable PPy nanospheres. The PPy nanospheres with the diameter of 100 nm exhibit the largest capacity and a good cycling stability as electrode materials of supercapacitors. The as-prepared PPy nanospheres also can be combined with carbon dots to form composite nanospheres presenting enhanced fluorescence intensity, which show potential application in fluorescence detection.

  2. The Impact of Computer Assisted Grammar Teaching on EFL Pupils' Performance in Jordan

    Science.gov (United States)

    Abu Naba'h, Abdallah M.

    2012-01-01

    This study aimed at investigating the impact of using computer assisted grammar teaching on the performance of Jordanian pupils studying English as a foreign language. The sample of the study consisted of (212) secondary pupils distributed randomly on four experimental groups and four control groups. To find out the impact of a software program on…

  3. Using Advance Organizers to Enhance Pupils' Achievement in Learning Poetry in English Language

    Science.gov (United States)

    Muiruri, Mary; Wambugu, Patriciah; Wamukuru, Kuria

    2016-01-01

    The study was a quasi-experimental that investigated the effects of Advance Organizers (AO) on achievement in poetry. Target population was class seven pupils of Nakuru North Sub-county primary schools in Kenya. 160 pupils were involved in the study. Four sampled schools were randomly assigned to control and experimental groups in Solomon Four…

  4. Preparation of size-controlled nanoparticles of magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Angela L., E-mail: angelaleao@iceb.ufop.br [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro P-3810193 (Portugal); Department of Chemistry, Federal University of Ouro Preto, 35400-000 Ouro Preto, Minas Gerais (Brazil); Valente, Manuel A. [Department of Physics, I3N, University of Aveiro, Aveiro P-3810193 (Portugal); Ferreira, Jose M.F. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro P-3810193 (Portugal); Fabris, Jose D. [Federal University of Jequitinhonha and Mucuri Valleys (UFVJM), 39100-000 Diamantina, Minas Gerais (Brazil)

    2012-05-15

    Samples of ferrofluids containing chemically stabilized nanoparticles of magnetite (Fe{sub 3}O{sub 4}) with tetramethylammonium hydroxide (TMAOH) were prepared by a direct reduction-precipitation method. The influences of aging time and temperature on the size and monodispersion characteristics of the produced nanoparticles were investigated. Transmission electron microscopy, powder X-ray diffraction, Fourier-transform infrared, and magnetization measurements with applied magnetic field up to 2 T were used to characterize the synthesized iron oxides. Raising the temperature of the synthesized material in autoclave affects positively the monodispersion of the nanoparticles, but it was not found to significantly influence the size itself of individual particles. - Highlights: Black-Right-Pointing-Pointer From report protocols, chemical synthesis of magnetite with FeCl{sub 3} (stable in air) instead of FeCl{sub 2} or Fe(NO{sub 3}){sub 3}, precursor. Black-Right-Pointing-Pointer Chemical reduction with Na{sub 2}SO{sub 3} provides an additional advantage. Black-Right-Pointing-Pointer As any eventual reformation of Fe{sup 3+} from reoxidization of produced Fe{sup 2+} may be sequestered by remaining SO{sub 3}{sup 2-} in the medium. Black-Right-Pointing-Pointer Nanoparticles are stably individualized with tetramethylammonium hydroxide that acts as a surface-active agent. Black-Right-Pointing-Pointer Thermal treatment reduces further the mean sizes of particles, as required for many medical uses.

  5. Size control synthesis of starch capped-gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tajammul Hussain, S., E-mail: dr_tajammul@yahoo.c [Quaid-i-Azam University, Centre for Nano Science and Catalysis, National Centre for Physics (Pakistan); Iqbal, M.; Mazhar, M. [Quaid-i-Azam University, Department of Chemistry (Pakistan)

    2009-08-15

    Metallic gold nanoparticles have been synthesized by the reduction of chloroaurate anions [AuCl{sub 4}]{sup -} solution with hydrazine in the aqueous starch and ethylene glycol solution at room temperature and at atmospheric pressure. The characterization of synthesized gold nanoparticles by UV-vis spectroscopy, high resolution transmission electron microscopy (HRTEM), electron diffraction analysis, X-ray diffraction (XRD), and X-rays photoelectron spectroscopy (XPS) indicate that average size of pure gold nanoparticles is 3.5 nm, they are spherical in shape and are pure metallic gold. The concentration effects of [AuCl{sub 4}]{sup -} anions, starch, ethylene glycol, and hydrazine, on particle size, were investigated, and the stabilization mechanism of Au nanoparticles by starch polymer molecules was also studied by FT-IR and thermogravimetric analysis (TGA). FT-IR and TGA analysis shows that hydroxyl groups of starch are responsible of capping and stabilizing gold nanoparticles. The UV-vis spectrum of these samples shows that there is blue shift in surface plasmon resonance peak with decrease in particle size due to the quantum confinement effect, a supporting evidence of formation of gold nanoparticles and this shift remains stable even after 3 months.

  6. Size controlled near-infrared high-quality PbSe quantum dots

    Science.gov (United States)

    Kalasad, M. N.; Rabinal, M. K.; Mulimani, B. G.; Greenham, N. C.

    2015-06-01

    Herein, we report the size controlled preparation of PbSe quantum dots (QDs) by non coordinating solvent route using oleic acid as surfactant molecules. The particles size is controlled by varying temperature and time of reaction. The present method of synthesis gives highly stable colloids, spherical in shape, better size tunability, narrow size distribution, extremely small size, monodisperse and exhibit strong near-infrared emission. The estimated particles sizes are in the range of 2 to 8 nm. These PbSe quantum dots are used for applications in optoelectronics and biological imaging.

  7. Does the "Pupil Enterprise Programme" Influence Grades among Pupils with Special Needs?

    Science.gov (United States)

    Johansen, Vegard; Somby, Hege M.

    2016-01-01

    This paper asks whether the Pupil Enterprise Programme (PEP) is a suitable working method for improving academic performance among pupils with special needs. Overall, 20% of pupils participate in PEP at some point during lower secondary school. Results from multilevel regression modelling indicate that pupils with special needs who have…

  8. The "subjective" pupil old/new effect: is the truth plain to see?

    Science.gov (United States)

    Montefinese, Maria; Ambrosini, Ettore; Fairfield, Beth; Mammarella, Nicola

    2013-07-01

    Human memory is an imperfect process, prone to distortion and errors that range from minor disturbances to major errors that can have serious consequences on everyday life. In this study, we investigated false remembering of manipulatory verbs using an explicit recognition task and pupillometry. Our results replicated the "classical" pupil old/new effect as well as data in false remembering literature that show how items must be recognize as old in order for the pupil size to increase (e.g., "subjective" pupil old/new effect), even though these items do not necessarily have to be truly old. These findings support the strength-of-memory trace account that affirms that pupil dilation is related to experience rather than to the accuracy of recognition. Moreover, behavioral results showed higher rates of true and false recognitions for manipulatory verbs and a consequent larger pupil diameter, supporting the embodied view of language.

  9. Smaller is better: drift in gaze measurements due to pupil dynamics.

    Science.gov (United States)

    Drewes, Jan; Zhu, Weina; Hu, Yingzhou; Hu, Xintian

    2014-01-01

    Camera-based eye trackers are the mainstay of eye movement research and countless practical applications of eye tracking. Recently, a significant impact of changes in pupil size on gaze position as measured by camera-based eye trackers has been reported. In an attempt to improve the understanding of the magnitude and population-wise distribution of the pupil-size dependent shift in reported gaze position, we present the first collection of binocular pupil drift measurements recorded from 39 subjects. The pupil-size dependent shift varied greatly between subjects (from 0.3 to 5.2 deg of deviation, mean 2.6 deg), but also between the eyes of individual subjects (0.1 to 3.0 deg difference, mean difference 1.0 deg). We observed a wide range of drift direction, mostly downward and nasal. We demonstrate two methods to partially compensate the pupil-based shift using separate calibrations in pupil-constricted and pupil-dilated conditions, and evaluate an improved method of compensation based on individual look-up-tables, achieving up to 74% of compensation.

  10. Is Chemistry Attractive for Pupils? Czech Pupils' Perception of Chemistry

    Science.gov (United States)

    Kubiatko, Milan

    2015-01-01

    Chemistry is an important subject due to understanding the composition and structure of the things around us. The main aim of the study was to find out the perception of chemistry by lower secondary school pupils. The partial aims were to find out the influence of gender, year of study and favorite subject on the perception of chemistry. The…

  11. Control of crystallite size in diamond film chemical vapor deposition

    Science.gov (United States)

    Moran, Mark B.; Johnson, Linda F.; Klemm, Karl A.

    1992-12-01

    In depositing an adhering, continuous, polycrystalline diamond film of optical or semiconductor quality on a substrate, as by forming on the substrate a layer of a refractory nitride interlayer and depositing diamond on the interlayer without mechanical treatment or seeding of the substrate or the interlayer, the substrate is heated in a vacuum chamber containing a microwave activated mixture of hydrogen and a gas including carbon, and the size of deposited diamond crystallites and their rate of deposition selectively varied by a bias voltage applied to the substrate.

  12. How Cells Can Control Their Size by Pumping Ions

    Directory of Open Access Journals (Sweden)

    Alan R. Kay

    2017-05-01

    Full Text Available The ability of all cells to set and regulate their size is a fundamental aspect of cellular physiology. It has been known for sometime but not widely so, that size stability in animal cells is dependent upon the operation of the sodium pump, through the so-called pump-leak mechanism (Tosteson and Hoffman, 1960. Impermeant molecules in cells establish an unstable osmotic condition, the Donnan effect, which is counteracted by the operation of the sodium pump, creating an asymmetry in the distribution of Na+ and K+ staving off water inundation. In this paper, which is in part a tutorial, I show how to model quantitatively the ion and water fluxes in a cell that determine the cell volume and membrane potential. The movement of water and ions is constrained by both osmotic and charge balance, and is driven by ion and voltage gradients and active ion transport. Transforming these constraints and forces into a set of coupled differential equations allows us to model how the ion distributions, volume and voltage change with time. I introduce an analytical solution to these equations that clarifies the influence of ion conductances, pump rates and water permeability in this multidimensional system. I show that the number of impermeant ions (x and their average charge have a powerful influence on the distribution of ions and voltage in a cell. Moreover, I demonstrate that in a cell where the operation of active ion transport eliminates an osmotic gradient, the size of the cell is directly proportional to x. In addition, I use graphics to reveal how the physico-chemical constraints and chemical forces interact with one another in apportioning ions inside the cell. The form of model used here is applicable to all membrane systems, including mitochondria and bacteria, and I show how pumps other than the sodium pump can be used to stabilize cells. Cell biologists may think of electrophysiology as the exclusive domain of neuroscience, however the electrical

  13. Understanding Pupils' Hiding Techniques in Physical Education

    Science.gov (United States)

    Lyngstad, Idar; Hagen, Per-Magnus; Aune, Ola

    2016-01-01

    Previous research shows that some pupils find physical education (PE) demanding and difficult. Some pupils use strategies to avoid participation in PE when it is demanding and difficult. The present study aims to illuminate and describe strategies used by pupils to avoid negative self-perception in difficult situations and activities in PE…

  14. Unilateral Adie's tonic pupil and viral hepatitis: Report of two cases

    Directory of Open Access Journals (Sweden)

    Karadžić Jelena

    2015-01-01

    Full Text Available Introduction. Adie’s (tonic pupil is a neuro-ophthalmological disorder characterized by a tonically dilated pupil, which is unresponsive to light. It is caused by damage to postganglionic fibers of the parasympathetic innervation of the eye, usually by a viral or bacterial infection. Adie’s syndrome includes diminished deep tendon reflexes. Outline of Cases. We report data of a 59-year-old female with unequal pupil sizes. She complained of blurred vision and headache mainly while reading. She had a 35-year history of hepatitis B and liver cirrhosis. On exam, left pupil was mydriatic and there was no response to light and at slit lamp we saw segments of the sphincter constrict. We performed 0.125% pilocarpine test and there was a remarkable reduction of size in the left pupil. The second case is a 55-year-old female who was referred to the University Eye Clinic because of a headache and mydriatic left pupil. She had diabetes mellitus type 2, as well as hepatitis A virus 20 years earlier. On exam, the left pupil was mydriatic, with no response to light. Test with diluted pilocarpine was positive. Neurological examinations revealed no abnormality in either case so we excluded Adie’s syndrome. Conclusion. Adie’s tonic pupil is benign neuro-ophthalmological disorder of unknown etiology. Most patients commonly present no symptoms and anisocoria is noticed accidentally. Although the etiology is unknown, there are some conditions that cause tonic pupil. It may be a part of a syndrome in which tonic pupil is associated with absent deep tendon reflexes.

  15. The modelling of the influence of a corneal geometry on the pupil image of the human eye

    Science.gov (United States)

    Szczesna, D. H.; Kasprzak, H. T.

    2006-07-01

    In normal conditions, a pupil of the eye is observed through the optical system of the cornea. The cornea is the anterior surface of the eye and is the major refractive element of the human eye. The influence of the corneal shape should not be neglected in measurements of the pupil size. The purpose of this study was to estimate the influence of the corneal geometry, the diameter of the pupil and its position in the anterior chamber on the magnification and position of the image of the pupil. The numerical calculations presented in the paper assume infinitely thin cornea, and the corneal topography was approximated by the elongated ellipsoid. The ray tracing procedure was used in our numerical modelling. The magnification of the pupil image amounted to about 10% and increases with decrease of radius of curvature and eccentricity of the corneal profile and decreases for the largest pupil. The results show also that the pupil image is placed nearer the corneal apex than the real pupil. The image of the pupil is always blurred, which limits the sharp observation of the pupil.

  16. Size-controlled nanoassemblies based on cyclodextrin-modified dextrans.

    Science.gov (United States)

    Wintgens, Véronique; Nielsen, Thorbjørn Terndrup; Larsen, Kim Lambertsen; Amiel, Catherine

    2011-09-09

    Nanoassemblies formed by host/guest interactions between two polymers in aqueous media are studied. Two types of polymers with the same dextran backbone are modified with adamantyl or βCD groups. The sizes of the spontaneously formed nanoassemblies depend on the βCD:Ada ratio and on the total concentration and composition of the mixtures. The results can be rationalized by assuming a core/shell structure of the nanoassemblies, the core resulting from associative phase separation of the two polymers and being stabilized by an external shell made of Ada-grafted dextran and containing ions adsorbed from the solution. Hydrophobic compounds such as benzophenone can be incorporated efficiently without inducing changes in properties of the nanoassemblies.

  17. Electronic structure and size of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods

    CERN Document Server

    Soriano, L; Sanchez-Agudo, M; Sanz, J M; Ahonen, P P; Kauppinen, E I; Palomares, F J; Bressler, P R

    2002-01-01

    A complete characterization of nanostructures has to deal both with electronic structure and dimensions. Here we present the characterization of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods. The electronic structure of these nanoparticles was probed by x-ray absorption spectroscopy (XAS), the particle size by atomic force microscopy (AFM). XAS spectra show that the particles crystallize in the anatase phase upon heating at 500 sup o C, whereas further annealing at 700 sup o C give crystallites of 70 % anatase and 30 % rutile phases. Raising the temperature to 900 sup o C results in a complete transformation of the particles to rutile. AFM images reveal that the mean size of the anatase particles formed upon heating at 500 sup o C is 30 nm, whereas for the rutile particles formed upon annealing at 900 sup o C 90 nm were found. The results obtained by these techniques agree with XRD data. (author)

  18. Social acceptance of gifted pupils and pupils with additional professional help in elementary school

    Directory of Open Access Journals (Sweden)

    Marina Horvat

    2014-02-01

    Full Text Available Studies of peer relations in school settings are typically conducted on normative samples of pupils. Less is known about subgroups of pupils with some exceptionalities who may be more vulnerable to developing peer problems in school and are subsequently at risk for later maladjustment. The purpose of present study was therefore to examine social acceptance of gifted pupils and pupils with additional professional help in 6th and 8th-grade of regular elementary school. 194 pupils (50.5% girls from 12 classes participated in the study; 16 of them (8.3% were pupils with additional professional help (APH, 39 gifted pupils (20.1% and one gifted pupil with APH. A composite positive and negative nomination sociometric procedure was employed. Most of the pupils with APH were in rejected and average sociometric group. Pupils with APH received the lowest number of positive and reciprocal nominations and the highest number of negative nominations. Compared to gifted pupils they were less accepted, although no difference in acceptance was found compared to the non-APH pupils. Results showed no significant differences in acceptance of pupils with APH in regard to grade level or gender. Gifted children received the highest number of positive and reciprocal and the lowest number of negative nominations. They were more likely to be average and popular, although no differences in acceptance was found compared to non-gifted pupils. Results suggest the importance of investigating subgroups of pupils with APH in future research.

  19. Fully Optimized Shaped Pupils for Arbitrary Apertures

    Science.gov (United States)

    Carlotti, Alexis; Vanderbei, R.; Kasdin, N. J.; Che, G.

    2012-01-01

    Optimal apodization masks for monolithic and segmented apertures are presented, with and without central obstruction and spider vanes. Examples of optimal masks are shown for several ground-based telescopes (The Subaru, Keck, Gemini, Palomar and Very Large telescopes). We also discuss the case of extremely large telescopes. Various high-contrast regions are considered with different inner and outer working angles, shapes and contrasts. These parameters are chosen to fit the specific constraints of each instrument, in particular those set by the dedicated coronagraphic adaptive optics system. Because of the limited size of the high-contrast regions, all the masks that result from these optimizations tend to have binary transmissions, and are thus as achromatic as previous shaped pupils. Effort is put on obtaining structurally connected masks. We intend to test these new shaped pupils in Princeton's high-contrast imaging laboratory, and to this end we explore different techniques to make the masks, such as cutting them in a metal layer, laying them on a glass substrate, or using a MOEMS device.

  20. The Texas Weighted Pupil Study.

    Science.gov (United States)

    Busselle, Tish Newman

    According to the weighted pupil philosophy, the essence of equal educational opportunity is not in providing equal amounts of funds for the education of each child, but in providing the varying amounts of funds needed to insure a financial basis for giving each child an equal opportunity to obtain an education which meets his needs. This paper…

  1. Three-zone pupil filters

    Science.gov (United States)

    Sheppard, Colin J. R.; Campos, Juan; Escalera, Juan C.; Ledesma, Silvia

    2008-07-01

    The performance of pupil filters consisting of three zones each of constant complex amplitude transmittance is investigated. For filters where the transmittance is real, different classes of potentially useful filter are identified. These include leaky filters with an inner zone of low amplitude transmittance, pure phase filters with phase change of π, and equal area filters.

  2. Middle School Pupils Write Haiku.

    Science.gov (United States)

    Ediger, Marlow

    Pupils in the middle school can be motivated to enjoy and write haiku poetry. A student teacher taught two lessons to a sixth grade class in haiku writing. First, the student teacher read three haikus aloud to students. After discovering the characteristics of a haiku from two models, the class as a whole wrote a haiku based on slides from their…

  3. Fractal images induce fractal pupil dilations and constrictions.

    Science.gov (United States)

    Moon, P; Muday, J; Raynor, S; Schirillo, J; Boydston, C; Fairbanks, M S; Taylor, R P

    2014-09-01

    Fractals are self-similar structures or patterns that repeat at increasingly fine magnifications. Research has revealed fractal patterns in many natural and physiological processes. This article investigates pupillary size over time to determine if their oscillations demonstrate a fractal pattern. We predict that pupil size over time will fluctuate in a fractal manner and this may be due to either the fractal neuronal structure or fractal properties of the image viewed. We present evidence that low complexity fractal patterns underlie pupillary oscillations as subjects view spatial fractal patterns. We also present evidence implicating the autonomic nervous system's importance in these patterns. Using the variational method of the box-counting procedure we demonstrate that low complexity fractal patterns are found in changes within pupil size over time in millimeters (mm) and our data suggest that these pupillary oscillation patterns do not depend on the fractal properties of the image viewed.

  4. Pupils teach to pupils about genetics or global warming

    Science.gov (United States)

    Cuny, Delphine

    2013-04-01

    The idea of this project is to put pupils in a teaching situation. Classes of teenagers go to primary schools and animate a science workshop. Junior pupils are separated in small groups and they attend two different sessions in the same half-day. The whole workshop consists of 4 sessions. Each session is organized with an activity (microscope observation, counting of chromosomes, drawing of a curve, etc.) in which senior pupils coach the younger, and ends with a debate or an assessment. The first experiment of this type of project was realized with a class of 14 to 15 year old pupils on the theme: How do your parents transmit your characteristics? The four sessions are attended in disorder but when knowledge of other sessions are necessary, senior pupils explain them at the beginning of the session. Junior pupils have a notebook to write their activities and to note their conclusions. Session 1: What did my father give to make me? Drawing and measuring microscopic observations of human spermatozoons. Conclusion: my father gave a spermatozoon which measures less than one mm long, this spermatozoon met my mother's egg and it made my first cell. Session 2: What does the program that made me look like? Microscope observation of blood cells, identification of chromosomes in the core. On microscope pictures, counting of chromosomes. Conclusion: My program is in each cell of my body, inside the core. Sometimes, in this core, we can observe short sticks that are called chromosomes. All human beings have the same number of chromosomes in their cells: 46. Session 3: Where do my chromosomes come from? Counting of chromosomes in spermatozoons or ovums and playing with sets of chromosomes to deduct sex of a baby. Conclusion: Daddy gave me 23 chromosomes and mummy gave me 23 chromosomes too. My program is then constituted from half of daddy's program and half of mummy's program. My brothers and sisters also have half and half, but not the same halves! Session 4: Where is the

  5. Grain size control and superplasticity in 6013-type aluminum alloys

    Science.gov (United States)

    Troeger, Lillianne Plaster Whitelock

    Aluminum alloys have been the material of choice for aircraft construction since the 1930's. Currently, the automotive industry is also showing an increasing interest in aluminum alloys as structural materials. 6xxx aluminum alloys possess a combination of strength and formability which makes them attractive to both industries. In addition, 6xxx alloys are highly weldable, corrosion resistant, and low in cost as compared with the 2xxx and 7xxx aluminum alloys. Superplastic forming (SPF) is a manufacturing process which exploits the phenomenon of superplasticity in which gas pressure is used to form complex-shaped parts in a single forming operation. This reduces part counts and the need for fasteners and connectors, resulting in reduced product weight. Reduced product/vehicle weight improves fuel economy. Most alloys must be specially processed for superplasticity. Much research effort has been directed at the development of thermomechanical processes for the grain refinement of aluminum alloys by static or dynamic recrystallization. to induce superplasticity. While large numbers of studies have been conducted on 2xxx, 5xxx, 7xxx, and 8xxx aluminum alloys, very few studies have been focused on the grain refinement of 6xxx aluminum alloys for superplasticity. The current research describes a new thermomechanical process for application to 6xxx aluminum alloys for grain refinement and superplasticity. The process is shown to successfully refine and induce superplasticity in an Al-Mg-Si-Cu alloy which falls within the compositional limits of both 6013 and 6111. The grain refinement is by particle-stimulated nucleation of recrystallization. The microstructural evolution during the thermomechanical processing is characterized in terms of precipitate size, shape, distribution and composition; texture; recrystallization; and grain size, shape, and thermal stability. The new process produces a statically-stable, weakly-textured, equiaxed grain structure with an average

  6. Particle Size Control for PIV Seeding Using Dry Ice

    Science.gov (United States)

    2010-03-01

    unsuccessful in forming discrete particles from either location and instead, gaseous CO2 clouds were present in the test section. Using the simple shroud...which was then kept pressurized by a pneumatic butterfly valve. The butterfly valve was operated and electronically controlled by a Fisher R© system. The...distribution was nonuniform , so even though a single number is presented to describe the particles at each test condition, the actual particles varied

  7. Size and shape control in the overgrowth of gold nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Ratto, Fulvio; Matteini, Paolo; Rossi, Francesca; Pini, Roberto, E-mail: r.pini@ifac.cnr.i [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche (Italy)

    2010-08-15

    We report on a new sustainable approach to manipulate the optical behaviour and geometrical properties of gold nanorods in aqueous solutions by fine control of their overgrowth. In our approach, the overgrowth is realized by modulation of the reduction of the gold ions which are left as Au{sup 1+} after the primary step of the synthesis (typically as much as {approx}80% of the gold ions available in the growth solution). The progress of the reduction requires the gradual addition of ascorbic acid, which transforms the Au{sup 1+} into Au{sup 0} and may be performed in the original growth solution with no need for any further manipulation. By control of the total amount and rate of administration of the ascorbic acid, we prove the possibility to realize a systematic modulation of the average lengths, diameters, shapes (rod or dog-bone like), and light extinction of the nanoparticles. A slow overgrowth leads to a gradual enlargement of the lengths and diameters at almost constant shape. In contrast, a faster overgrowth results into a more complex modification of the overall shape of the gold nanorods.

  8. Disciplinary Technologies and Pupil Redisposition: School Equipment and Homework Diaries

    Science.gov (United States)

    Zaborowski, Katrin U.; Breidenstein, Georg

    2011-01-01

    This paper explores disciplinary technologies and pupil redisposition through school and teacher focus on school equipment and homework diaries. During our field research in two contrasting secondary schools, we experienced the importance of missing school equipment to teacher and school control. We also concluded that forgotten or missing school…

  9. Quantitative assessment of the impact of blood pulsation on images of the pupil in infrared light.

    Science.gov (United States)

    Koprowski, Robert; Szmigiel, Marta; Kasprzak, Henryk; Wróbel, Zygmunt; Wilczyński, Sławomir

    2015-08-01

    Pulsation in the blood vessels of the eye has a big impact on the dynamics of the entire eyeball and its individual elements. Blood pulsation in the retina can be recorded by the pupil, whose size is also subject to dynamic changes. The study involved synchronous measurements of pupil size using a high-speed camera, and blood pulsation using a pulse oximeter placed on the ear lobe. In addition, there were no metrologically significant differences in the phase shift between the average brightness of the individual pupil quadrants. Blood pulsation in other ocular tissues can affect the dynamics of the optical properties of the eye. As demonstrated in this paper, it affects the pupil behavior and its parameters to a considerable extent.

  10. Development of an Autonomous Flight Control System for Small Size Unmanned Helicopter Based on Dynamical Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It is devoted to the development of an autonomous flight control system for small size unmanned helicopter based on dynamical model. At first, the mathematical model of a small size helicopter is described. After that simple but effective MTCV control algorithm was proposed. The whole flight control algorithm is composed of two parts:orientation controller based on the model for rotation dynamics and a robust position controller for a double integrator. The MTCV block is also used to achieve translation velocity control. To demonstrate the performance of the presented algorithm, simulation results and results achieved in real flight experiments were presented.

  11. Circadian and wake-dependent effects on the pupil light reflex in response to narrow-bandwidth light pulses.

    Science.gov (United States)

    Münch, Mirjam; Léon, Lorette; Crippa, Sylvain V; Kawasaki, Aki

    2012-07-03

    Nonvisual light-dependent functions in humans are conveyed mainly by intrinsically photosensitive retinal ganglion cells, which express melanopsin as photopigment. We aimed to identify the effects of circadian phase and sleepiness across 24 hours on various aspects of the pupil response to light stimulation. We tested 10 healthy adults hourly in two 12-hour sessions covering a 24-hour period. Pupil responses to narrow bandwidth red (635 ± 18 nm) and blue (463 ± 24 nm) light (duration of 1 and 30 seconds) at equal photon fluxes were recorded, and correlated with salivary melatonin concentrations at the same circadian phases and to subjective sleepiness ratings. The magnitude of pupil constriction was determined from minimal pupil size. The post-stimulus pupil response was assessed from the pupil size at 6 seconds following light offset, the area within the redilation curve, and the exponential rate of redilation. Among the measured parameters, the pupil size 6 seconds after light offset correlated with melatonin concentrations (P light stimulation correlated with subjective sleepiness (P light as a marker of intrinsic melanopsin activity demonstrated a circadian modulation. In contrast, the effect of sleepiness was more apparent in the cone contribution to the pupil response. Thus, pupillary responsiveness to light is under influence of the endogenous circadian clock and subjective sleepiness.

  12. On written expression of primary school pupils

    Directory of Open Access Journals (Sweden)

    Stevanović Jelena

    2009-01-01

    Full Text Available Normative rules of standard Serbian language are acquired during primary and secondary education through curriculum demands of Serbian language instruction, which takes place in three fields: grammar, orthography and culture of expression. Topic of interest in this paper is the quality of written expression of 6th and 7th grade pupils, in the context of all three fields specified to be mastered by the curriculum of Serbian language. Research comprised 148 primary school pupils from Belgrade. Linguistic analysis of spontaneously created written text was performed, in the conditions where it was not explicitly demanded form the pupil to write correctly. The results indicate that the majority of pupils make spelling and grammatical errors, meeting the condition for the basic level of mastering the knowledge in Serbian language according to the standards specified for the end of compulsory education. In addition to this, a considerable majority of pupils has a satisfactory level of culture of written expression. Pupils more often make spelling than grammatical errors. Seventh grade pupils are better than sixth grade pupils with respect to adhering to grammar rules and according to culture of written expression, while the mark in Serbian language and general school achievement of pupils correlate only with the degree of adhering to the orthographic rules. It was concluded that not only individual programs of support for pupils who make more errors are necessary, but also launching national projects for the development of linguistic competence of the young in Serbia.

  13. Recrystallization Behavior Design for Controlling Grain Size in Strip Rolling Process

    Institute of Scientific and Technical Information of China (English)

    ZHU Guo-hui; S V Subramanian

    2008-01-01

    To promote effectively dynamic recrystallization and obtain a homogeneous distribution of ultrafine grain size in strip finish rolling process, the behavior of static and dynamic recrystallization must be appropriately designed to provide an ultrafine austenite microstructure without mixed grain size. The design of rolling schedule was analyzed based on the control of the recrystallization behavior to achieve ultrafine grain size in the strip rolling process of niobium microalloyed steel. The experimental simulations were presented to validate the twice dynamic recrystallization design to achieve ultrafine grain size control.

  14. Phanerozoic size history of the foraminifera: Implications for environmental and biological controls on macroevolutionary trends

    Science.gov (United States)

    Payne, J.; Jost, A. B.; Cummins, R.; Tachiki, N.; Ingram, K.

    2009-12-01

    Size is among the most important ecological characteristics of any organism, correlating with a wide variety of traits from metabolic rate to generation time. Although there have been numerous studies of body size evolution in the fossil record, few have spanned multiple geological eras. Thus, the effect of environmental changes occurring on Wilson-cycle timescales (hundreds of millions of years) on the evolution of size remains poorly understood. We compiled a comprehensive genus-level size database for benthic foraminifers through Phanerozoic time. We find that the average size of calcareous benthic foraminifers increased gradually through the Late Paleozoic, reaching local maxima in mean and maximum size during the Early Permian. Sizes decreased to a relative minimum during the Early Triassic before increasing gradually to a second local maximum in the Late Cretaceous (for maximum size) and early Paleogene (for mean size). Close resemblance of trends in mean size to trends in atmospheric oxygen concentrations suggest either oxygen has been an important driver of size evolution or the two variables share a common control. Superimposed on these long-term trends are signatures of the major extinction events. Four of the five largest drops in mean size occur in association with the Middle Permian (Guadalupian), end-Permian, end-Triassic, and end-Cretaceous mass extinctions. Thus, the Phanerozoic size history of benthic foraminifera appears to have been driven primarily by long-term and short-term environmental change.

  15. Pupil measures of alertness and mental load

    Science.gov (United States)

    Backs, Richard W.; Walrath, Larry C.

    1988-01-01

    A study of eight adults given active and passive search tasks showed that evoked pupillary response was sensitive to information processing demands. In particular, large pupillary diameter was observed in the active search condition where subjects were actively processing information relevant to task performance, as opposed to the passive search (control) condition where subjects passively viewed the displays. However, subjects may have simply been more aroused in the active search task. Of greater importance was that larger pupillary diameter, corresponding to longer search time, was observed for noncoded than for color-coded displays in active search. In the control condition, pupil diameter was larger with the color displays. The data indicate potential usefulness of pupillary responses in evaluating the information processing requirements of visual displays.

  16. The impact of a multiple intelligences teaching approach drug education programme on drug refusal skills of Nigerian pupils.

    Science.gov (United States)

    Nwagu, Evelyn N; Ezedum, Chuks E; Nwagu, Eric K N

    2015-09-01

    The rising incidence of drug abuse among youths in Nigeria is a source of concern for health educators. This study was carried out on primary six pupils to determine the effect of a Multiple Intelligences Teaching Approach Drug Education Programme (MITA-DEP) on pupils' acquisition of drug refusal skills. A programme of drug education based on the Multiple Intelligences Teaching Approach (MITA) was developed. An experimental group was taught using this programme while a control group was taught using the same programme but developed based on the Traditional Teaching Approach. Pupils taught with the MITA acquired more drug refusal skills than those taught with the Traditional Teaching Approach. Urban pupils taught with the MITA acquired more skills than rural pupils. There was no statistically significant difference in the mean refusal skills of male and female pupils taught with the MITA.

  17. Pupil Mimicry Correlates With Trust in In-Group Partners With Dilating Pupils.

    Science.gov (United States)

    Kret, M E; Fischer, A H; De Dreu, C K W

    2015-09-01

    During close interactions with fellow group members, humans look into one another's eyes, follow gaze, and quickly grasp emotion signals. The eye-catching morphology of human eyes, with unique eye whites, draws attention to the middle part, to the pupils, and their autonomic changes, which signal arousal, cognitive load, and interest (including social interest). Here, we examined whether and how these changes in a partner's pupils are processed and how they affect the partner's trustworthiness. Participants played incentivized trust games with virtual partners, whose pupils dilated, remained static, or constricted. Results showed that (a) participants trusted partners with dilating pupils and withheld trust from partners with constricting pupils, (b) participants' pupils mimicked changes in their partners' pupils, and (c) dilation mimicry predicted trust in in-group partners, whereas constriction mimicry did not. We suggest that pupil-contingent trust is in-group bounded and possibly evolved in and because of group life.

  18. Particle Size Controls on Water Adsorption and Condensation Regimes at Mineral Surfaces

    OpenAIRE

    Merve Yeşilbaş; Jean-François Boily

    2016-01-01

    Atmospheric water vapour interacting with hydrophilic mineral surfaces can produce water films of various thicknesses and structures. In this work we show that mineral particle size controls water loadings achieved by water vapour deposition on 21 contrasting mineral samples exposed to atmospheres of up to ~16 Torr water (70% relative humidity at 25 °C). Submicrometer-sized particles hosted up to ~5 monolayers of water, while micrometer-sized particles up to several thousand monolayers. All f...

  19. Gallstone size and the risk of gallbladder cancer, a hospital based case-control study

    NARCIS (Netherlands)

    Moerman CJ; Lagerwaard FJ; Bueno de Mesquita HB; van Dalen A; van Leeuwen MS; Schrover PAHAM; Berns MPH

    1992-01-01

    The relation between gallstone size and gallbladder cancer was studied in a hospital based case-control study. Cases were selected on abdominal surgery. The selection criterion for controls was a cholecystectomy performed for a benign gallbladder disorder. Controls were matched with cases on sex,

  20. UNICS - An Unified Instrument Control System for Small/Medium Sized Astronomical Observatories

    CERN Document Server

    Srivastava, Mudit K; Burse, Mahesh P; Chordia, Pravin A; Chillal, Kalpesh S; Mestry, Vilas B; Das, Hillol K; Kohok, Abhay A

    2009-01-01

    Although the astronomy community is witnessing an era of large telescopes, smaller and medium sized telescopes still maintain their utility being larger in numbers. In order to obtain better scientific outputs it is necessary to incorporate modern and advanced technologies to the back-end instruments and to their interfaces with the telescopes through various control processes. However often tight financial constraints on the smaller and medium size observatories limit the scope and utility of these systems. Most of the time for every new development on the telescope the back-end control systems are required to be built from scratch leading to high costs and efforts. Therefore a simple, low cost control system for small and medium size observatory needs to be developed to minimize the cost and efforts while going for the expansion of the observatory. Here we report on the development of a modern, multipurpose instrument control system UNICS (Unified Instrument Control System) to integrate the controls of vari...

  1. The online behavior of pupils with visual impairment: A preliminary report.

    Science.gov (United States)

    Wrzesińska, Magdalena; Tabała, Klaudia; Stecz, Patryk

    2016-10-01

    Young people with special educational needs are also users of new media. The aim of the study was to determine whether pupils with visual impairment spend more time on Internet use than pupils without visual impairment and whether youngsters from the study group are engaged in behaviors which could increase risk of problematic Internet use. The study is based on a total of 191 pupils: a study group of 66 partially-sighted pupils and a control group comprised 125 pupils who do not have visual impairment. A self-report questionnaire was constructed for the needs of this study. Pupils with visual impairment spent significantly less time on Internet use than their peers from the reference groups. Twice as many pupils from the study group as controls reported no symptoms suggesting potentially problematic Internet use. In addition, the study group more frequently used online social networking services and e-mails or used the Internet for assignments. Little difference exists between students with visual impairment and those without with regard to Internet use. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Pupils as Active Participants: Diamond Ranking as a Tool to Investigate Pupils' Experiences of Classroom Practices

    Science.gov (United States)

    Niemi, Reetta; Kumpulainen, Kristiina; Lipponen, Lasse

    2015-01-01

    This article is based on a pedagogical action research initiative carried out in a Finnish primary school. Twenty-four 5th grade pupils and their teacher participated in the study. The research initiative was guided by two questions: (1) How do pupils experience their classroom practices? (2) How can pupils participate in the process of developing…

  3. Generation of nanoparticles of controlled size using ultrasonic piezoelectric oscillators in solution.

    Science.gov (United States)

    Wright, Ian K; Higginbotham, Andrew; Baker, Shenda M; Donnelly, T D

    2010-08-01

    We demonstrate the operation of a device that can produce chitosan nanoparticles in a tunable size range from 50-300 nm with small size dispersion. A piezoelectric oscillator operated at megahertz frequencies is used to aerosolize a solution containing dissolved chitosan. The solvent is then evaporated from the aerosolized droplets in a heat pipe, leaving monodisperse nanoparticles to be collected. The nanoparticle size is controlled both by the concentration of the dissolved polymer and by the size of the aerosol droplets that are created. Our device can be used with any polymer or polymer/therapeutic combination that can be prepared in a homogeneous solution and vaporized.

  4. Pupil dilation dynamics track attention to high-level information.

    Directory of Open Access Journals (Sweden)

    Olivia E Kang

    Full Text Available It has long been thought that the eyes index the inner workings of the mind. Consistent with this intuition, empirical research has demonstrated that pupils dilate as a consequence of attentional effort. Recently, Smallwood et al. (2011 demonstrated that pupil dilations not only provide an index of overall attentional effort, but are time-locked to stimulus changes during attention (but not during mind-wandering. This finding suggests that pupil dilations afford a dynamic readout of conscious information processing. However, because stimulus onsets in their study involved shifts in luminance as well as information, they could not determine whether this coupling of stimulus and pupillary dynamics reflected attention to low-level (luminance or high-level (information changes. Here, we replicated the methodology and findings of Smallwood et al. (2011 while controlling for luminance changes. When presented with isoluminant digit sequences, participants' pupillary dilations were synchronized with stimulus onsets when attending, but not when mind-wandering. This replicates Smallwood et al. (2011 and clarifies their finding by demonstrating that stimulus-pupil coupling reflects online cognitive processing beyond sensory gain.

  5. Size and shape controllable preparation of graphene sponge by freezing, lyophilizing and reducing in container

    Institute of Scientific and Technical Information of China (English)

    ZHAO LianQin; YU BaoWei; ZHANG XiaoLiang; WU RuiHan; LIU XiaoYang; LIAO Rong; YANG ShengTao

    2016-01-01

    Graphene sponge (GS) is a porous 3D structure of graphene.Although hydrothermal reduction,chemical vapor deposition,solution reduction and high temperature annealing could be used for the preparation of GS,the size and shape cannot be well controlled.Herein,we reported a facile method to prepare GS under mild condition in a size and shape controllable way.Graphene oxide was lyophilized to form the spongy structure and reduced by steamy hydrazine hydrate to produce GS.The size and shape of GS prepared were nearly identical to that of the container.The reduction degree of GS could be regulated by the reduction temperature and time.

  6. CONTROL OF POLYMER PARTICLE SIZE USING POROUS GLASS MEMBRANE EMULSIFICATION A REVIEW

    Institute of Scientific and Technical Information of China (English)

    Guanghui Ma

    2003-01-01

    Much attention has in recent years been paid to fine applications of polymer particles, e.g., carrier for enzyme, separation media for protein, DNA and cell, and carrier for drug in Drug Delivery System (DDS). Control of polymer particle size is especially important in such fine applications. For instance, when the particles are used as a carrier of anti-cancer agents, the locations of particles containing anti-cancer agents also depend on the size of the particles. In this paper, various techniques of controlling polymer particle size are described, with emphasis on Shirasu Porous Glass (SPG) membrane emulsification, as carried out in our research group.

  7. Wireless magnetic sensors applied in the signal control of small and medium-sized cities

    Institute of Scientific and Technical Information of China (English)

    Liang Zijun; Zhang Bo; Huang Zhen; Song Zhihong

    2015-01-01

    This topic is mainly about the typical applications of Wireless magnetic sensors in the signal control of smal and medium-sized cities. Based on the traffic characteristics of Fenghua city, through the networked control of Wireless magnetic sensors and signal controler, from "point, line, face" three aspects to optimize the traffic flow of Fenghua. The application results show that Wireless magnetic sensors can effectively improve the efficiency of traffic signal control in Fenghua.

  8. Temporal characteristics of melanopsin inputs to the human pupil light reflex.

    Science.gov (United States)

    Joyce, Daniel S; Feigl, Beatrix; Cao, Dingcai; Zele, Andrew J

    2015-02-01

    Rods, cones and melanopsin containing intrinsically photosensitive retinal ganglion cells (ipRGCs) operate in concert to regulate pupil diameter. The temporal properties of intrinsic ipRGC signalling are distinct to those of rods and cones, including longer latencies and sustained signalling after light offset. We examined whether the melanopsin mediated post-illumination pupil response (PIPR) and pupil constriction were dependent upon the inter-stimulus interval (ISI) between successive light pulses and the temporal frequency of sinusoidal light stimuli. Melanopsin excitation was altered by variation of stimulus wavelength (464 nm and 638 nm lights) and irradiance (11.4 and 15.2 log photons cm(-2) s(-1)). We found that 6s PIPR amplitude was independent of ISI and temporal frequency for all melanopsin excitation levels, indicating complete summation. In contrast to the PIPR, the maximum pupil constriction increased with increasing ISI with high and low melanopsin excitation, but time to minimum diameter was slower with high melanopsin excitation only. This melanopsin response to briefly presented pulses (16 and 100 ms) slows the temporal response of the maximum pupil constriction. We also demonstrate that high melanopsin excitation attenuates the phasic peak-trough pupil amplitude compared to conditions with low melanopsin excitation, indicating an interaction between inner and outer retinal inputs to the pupil light reflex. We infer that outer retina summation is important for rapidly controlling pupil diameter in response to short timescale fluctuations in illumination and may occur at two potential sites, one that is presynaptic to extrinsic photoreceptor input to ipRGCs, or another within the pupil control pathway if ipRGCs have differential temporal tuning to extrinsic and intrinsic signalling.

  9. Reducing sample size in experiments with animals: historical controls and related strategies.

    Science.gov (United States)

    Kramer, Matthew; Font, Enrique

    2017-02-01

    Reducing the number of animal subjects used in biomedical experiments is desirable for ethical and practical reasons. Previous reviews of the benefits of reducing sample sizes have focused on improving experimental designs and methods of statistical analysis, but reducing the size of control groups has been considered rarely. We discuss how the number of current control animals can be reduced, without loss of statistical power, by incorporating information from historical controls, i.e. subjects used as controls in similar previous experiments. Using example data from published reports, we describe how to incorporate information from historical controls under a range of assumptions that might be made in biomedical experiments. Assuming more similarities between historical and current controls yields higher savings and allows the use of smaller current control groups. We conducted simulations, based on typical designs and sample sizes, to quantify how different assumptions about historical controls affect the power of statistical tests. We show that, under our simulation conditions, the number of current control subjects can be reduced by more than half by including historical controls in the analyses. In other experimental scenarios, control groups may be unnecessary. Paying attention to both the function and to the statistical requirements of control groups would result in reducing the total number of animals used in experiments, saving time, effort and money, and bringing research with animals within ethically acceptable bounds. © 2015 Cambridge Philosophical Society.

  10. A computer module used to calculate the horizontal control surface size of a conceptual aircraft design

    Science.gov (United States)

    Sandlin, Doral R.; Swanson, Stephen Mark

    1990-01-01

    The creation of a computer module used to calculate the size of the horizontal control surfaces of a conceptual aircraft design is discussed. The control surface size is determined by first calculating the size needed to rotate the aircraft during takeoff, and, second, by determining if the calculated size is large enough to maintain stability of the aircraft throughout any specified mission. The tail size needed to rotate during takeoff is calculated from a summation of forces about the main landing gear of the aircraft. The stability of the aircraft is determined from a summation of forces about the center of gravity during different phases of the aircraft's flight. Included in the horizontal control surface analysis are: downwash effects on an aft tail, upwash effects on a forward canard, and effects due to flight in close proximity to the ground. Comparisons of production aircraft with numerical models show good accuracy for control surface sizing. A modified canard design verified the accuracy of the module for canard configurations. Added to this stability and control module is a subroutine that determines one of the three design variables, for a stable vectored thrust aircraft. These include forward thrust nozzle position, aft thrust nozzle angle, and forward thrust split.

  11. Attitude angle anti-windup control of small size unmanned helicopter

    Science.gov (United States)

    Shao, Taizhou; Long, Haihui; Zhao, Jiankang; Xia, Xuan; Yang, Guang

    2017-01-01

    This paper researches the small-size unmanned helicopter attitude control problem with actuator saturation limit. Traditional approach for this problem is often based on an accurate dynamic model which is complicated and difficult to achieve in engineering. In this paper, we propose an anti-windup PID approach which does not rely on sophicated helicopter dynamic model. The anti-windup PID controller is established by adding a phase-lead compensator to the conventional PID controller. The performance and merits of this proposed controller are exemplified by the simulations between the conventional PID controller and the anti-windup PID controller.

  12. Pathophysiology of dilatation of pupils due to scorpion and snake envenomation and its therapeutic value: Clinical observations

    Science.gov (United States)

    Bawaskar, Himmatrao S; Bawaskar, Parag H; Bawaskar, Pramodini H

    2017-01-01

    Dilated nonreacting pupils are routinely taken as a sign of irreversible brain damage. Alpha-receptor stimulation (scorpion sting) and presynaptic acetylcholine receptor blocker (krait bite) may result in dilation of pupils without involvement of the brain. This study was aimed to clinically evaluate the response of pupils in scorpion sting and krait bite. Victims of scorpion sting and krait bite were chosen from Raigad district. Scorpion sting and krait bite cases were admitted to hospital and were clinically evaluated in detail regarding neurological manifestations. Both cases had nonreacting dilation of pupils, complete neurological recovery accompanied with reverse of pupillary size and its response to light. In scorpion sting and krait bite poisoning, dilated nonreacting pupils are not the signs of irreversible brain damage. PMID:28300747

  13. Pupil Absenteeism and the Educational Psychologist

    Science.gov (United States)

    Carroll, H. C. M.

    2015-01-01

    From a review of the literature, it is concluded that (i) each form of pupil absenteeism relates to a heterogeneous group of children; (ii) because of such heterogeneity, those who are involved in assessment and intervention in relation to pupil absenteeism are faced with a demanding task; (iii) as a consequence of their education and training,…

  14. Ability of Slovakian Pupils to Identify Birds

    Science.gov (United States)

    Prokop, Pavol; Rodak, Rastislav

    2009-01-01

    A pupil's ability to identify common organisms is necessary for acquiring further knowledge of biology. We investigated how pupils were able to identify 25 bird species following their song, growth habits, or both features presented simultaneously. Just about 19% of birds were successfully identified by song, about 39% by growth habit, and 45% of…

  15. Turkish Primary School Pupils' Views on Punishment

    Science.gov (United States)

    Aydin, Bahri

    2010-01-01

    Teachers meet with unwanted behavior when they are acting as facilitators of the learning process and they resort to certain tactics to deal with them. One of these tactics is punishment. This study aimed to identify the views held by Turkish primary school pupils on punishment. According to the results of the study, pupils were punished for…

  16. Pupils' involvement in ecological activities in school

    Directory of Open Access Journals (Sweden)

    Stanišić Jelena

    2009-01-01

    Full Text Available Ecological education gains an increasing importance in the moment when ecological crisis acquires increasingly larger proportions. Education is one of the most powerful social means in fighting problems and challenges of the future. This paper presents the results of the research referring to pupils' attitudes with respect to the activities they prefer to be involved in, the independent variables their readiness for involvement depends on, as well as the relation between the knowledge possessed by pupils and their readiness to be involved in ecological activities. Research was conducted on the sample of 284 pupils in the eighth grade of primary school in urban and rural area and polluted and unpolluted environment. The results indicate that pupils find more interesting the activities taking place in nature, those where they are immediate participants and those where they have a subjective feeling that they are doing something to protect the environment. Besides, the results show that girls from both samples and pupils from rural area are more ready to get involved in ecological activities. Living in polluted or unpolluted environment is not a statistically significant variable which would influence the readiness of pupils to get involved in these activities. As the most interesting result of this research, we consider the finding that a higher level of pupils' ecological knowledge and living in polluted environment do not guarantee higher readiness of pupils to get involved in the activities of environment protection.

  17. Plasmon-Enhanced Photoelectrochemical Water Splitting with Size-Controllable Gold Nanodot Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kim, HJ; Lee, SH; Upadhye, AA; Ro, I; Tejedor-Tejedor, MI; Anderson, MA; Kim, WB; Huber, GW

    2014-10-01

    Size-controllable Au nanodot arrays (50, 63, and 83 nm dot size) with a narrow size distribution (+/- 5%) were prepared by a direct contact printing method on an indium tin oxide (ITO) substrate. Titania was added to the Au nanodots using TiO2 sols of 2-3 nm in size. This created a precisely controlled Au nanodot with 110 nm of TiO2 overcoats. Using these precisely controlled nanodot arrays, the effects of Au nanodot size and TiO2 overcoats were investigated for photoelectrochemical water splitting using a three-electrode system with a fiber-optic visible light source. From UV-vis measurement, the localized surface plasmon resonance (LSPR) peak energy (ELSPR) increased and the LSPR line width (G) decreased with decreasing Au nanodot size. The generated plasmonic enhancement for the photoelectrochemical water splitting reaction increased with decreasing Au particle size. The measured plasmonic enhancement for light on/off experiments was 25 times for the 50 nm Au size and 10 times for the 83 nm Au nanodot size. The activity of each catalyst increased by a factor of 6 when TiO2 was added to the Au nanodots for all the samples. The activity of the catalyst was proportional to the quality factor (defined as Q = E-LSPR/Gamma) of the plasmonic metal nanostructure. The enhanced water splitting performance with the decreased Au nanodot size is probably due to more generated charge carriers (electron/hole pair) by local field enhancement as the quality factor increases.

  18. Control of root meristem size by DA1-RELATED PROTEIN2 in Arabidopsis.

    Science.gov (United States)

    Peng, Yuancheng; Ma, Wenying; Chen, Liangliang; Yang, Lei; Li, Shengjun; Zhao, Hongtao; Zhao, Yankun; Jin, Weihuan; Li, Na; Bevan, Michael W; Li, Xia; Tong, Yiping; Li, Yunhai

    2013-03-01

    The control of organ growth by coordinating cell proliferation and differentiation is a fundamental developmental process. In plants, postembryonic root growth is sustained by the root meristem. For maintenance of root meristem size, the rate of cell differentiation must equal the rate of cell division. Cytokinin and auxin interact to affect the cell proliferation and differentiation balance and thus control root meristem size. However, the genetic and molecular mechanisms that determine root meristem size still remain largely unknown. Here, we report that da1-related protein2 (dar2) mutants produce small root meristems due to decreased cell division and early cell differentiation in the root meristem of Arabidopsis (Arabidopsis thaliana). dar2 mutants also exhibit reduced stem cell niche activity in the root meristem. DAR2 encodes a Lin-11, Isl-1, and Mec-3 domain-containing protein and shows an expression peak in the border between the transition zone and the elongation zone. Genetic analyses show that DAR2 functions downstream of cytokinin and SHORT HYPOCOTYL2 to maintain normal auxin distribution by influencing auxin transport. Further results indicate that DAR2 acts through the PLETHORA pathway to influence root stem cell niche activity and therefore control root meristem size. Collectively, our findings identify the role of DAR2 in root meristem size control and provide a novel link between several key regulators influencing root meristem size.

  19. SCF(SAP) controls organ size by targeting PPD proteins for degradation in Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Zhibiao; Li, Na; Jiang, Shan; Gonzalez, Nathalie; Huang, Xiahe; Wang, Yingchun; Inzé, Dirk; Li, Yunhai

    2016-04-06

    Control of organ size by cell proliferation and growth is a fundamental process, but the mechanisms that determine the final size of organs are largely elusive in plants. We have previously revealed that the ubiquitin receptor DA1 regulates organ size by repressing cell proliferation in Arabidopsis. Here we report that a mutant allele of STERILE APETALA (SAP) suppresses the da1-1 mutant phenotype. We show that SAP is an F-box protein that forms part of a SKP1/Cullin/F-box E3 ubiquitin ligase complex and controls organ size by promoting the proliferation of meristemoid cells. Genetic analyses suggest that SAP may act in the same pathway with PEAPOD1 and PEAPOD2, which are negative regulators of meristemoid proliferation, to control organ size, but does so independently of DA1. Further results reveal that SAP physically associates with PEAPOD1 and PEAPOD2, and targets them for degradation. These findings define a molecular mechanism by which SAP and PEAPOD control organ size.

  20. Analysis of pupil and corneal wave aberration data supplied by the SN CT 1000 topography system

    Science.gov (United States)

    Comastri, S. A.; Martin, G.; Pfortner, T.

    2006-11-01

    Ocular aberrations depend on pupil size and centring and the retinal image quality under natural conditions differs from that corresponding to laboratory ones. In the present article, pupil and wave aberration data supplied by the Shin Nippon CT 1000 (SN CT 1000) topography system are analysed. Two groups of eyes under natural viewing conditions are considered ((260+/-20) lux at the eye under study). The first group consists of 10 normal eyes (-1.25 to 3 D sphere; 0 to -1.75 D cylinder) of five young subjects (age between 18 and 33 years). For this group, five determinations per eye are performed and the repeatability of results is analysed. Pupil centre is displaced from corneal vertex towards the temporal region, the largest displacement being (0.5+/-0.1) mm. The variation of pupil diameter in each eye is less than 21% while the inter-subject variability is large since diameters are between (3+/-0.3) and (5.3+/-0.6) mm. Aberrations are evaluated for two different pupil sizes, the natural one and a fictitious one of 6 mm. The corneal higher-order root-mean square wavefront error (RMSHO) for a 6 mm pupil centred in the corneal vertex, averaged across all eyes, is (0.37+/-0.06) [mu]m while, considering the natural pupil diameter, the average in each eye is significantly lower, up to eight times smaller. The fourth-order spherical aberration is an important aberration in the considered eyes, its maximum value for a 6 mm pupil being (0.38+/-0.02) [mu]m. The second group consists of 24 eyes of 12 subjects (age between 25 and 68 years) such that four eyes are of normal adults (1.25 to +6 D sphere; 0 to -0.5 D cylinder), eight have astigmatisms (-5.5 to +3.25 D sphere; -1.5 to -4.5 D cylinder), six have post-refractive surgery (+0.5 to +3.5 D sphere; -0.5 to -4 D cylinder) and six have keratoconus (-9.5 to +1 D sphere; -1 to -4.5 D cylinder). For this group only one determination per eye is performed. Pupil centre is displaced from corneal vertex towards the temporal

  1. Environmental and biotic controls on the evolutionary history of insect body size.

    Science.gov (United States)

    Clapham, Matthew E; Karr, Jered A

    2012-07-03

    Giant insects, with wingspans as large as 70 cm, ruled the Carboniferous and Permian skies. Gigantism has been linked to hyperoxic conditions because oxygen concentration is a key physiological control on body size, particularly in groups like flying insects that have high metabolic oxygen demands. Here we show, using a dataset of more than 10,500 fossil insect wing lengths, that size tracked atmospheric oxygen concentrations only for the first 150 Myr of insect evolution. The data are best explained by a model relating maximum size to atmospheric environmental oxygen concentration (pO(2)) until the end of the Jurassic, and then at constant sizes, independent of oxygen fluctuations, during the Cretaceous and, at a smaller size, the Cenozoic. Maximum insect size decreased even as atmospheric pO(2) rose in the Early Cretaceous following the evolution and radiation of early birds, particularly as birds acquired adaptations that allowed more agile flight. A further decrease in maximum size during the Cenozoic may relate to the evolution of bats, the Cretaceous mass extinction, or further specialization of flying birds. The decoupling of insect size and atmospheric pO(2) coincident with the radiation of birds suggests that biotic interactions, such as predation and competition, superseded oxygen as the most important constraint on maximum body size of the largest insects.

  2. Estimation of mental effort in learning visual search by measuring pupil response.

    Directory of Open Access Journals (Sweden)

    Tatsuto Takeuchi

    Full Text Available Perceptual learning refers to the improvement of perceptual sensitivity and performance with training. In this study, we examined whether learning is accompanied by a release from mental effort on the task, leading to automatization of the learned task. For this purpose, we had subjects conduct a visual search for a target, defined by a combination of orientation and spatial frequency, while we monitored their pupil size. It is well known that pupil size reflects the strength of mental effort invested in a task. We found that pupil size increased rapidly as the learning proceeded in the early phase of training and decreased at the later phase to a level half of its maximum value. This result does not support the simple automatization hypothesis. Instead, it suggests that the mental effort and behavioral performance reflect different aspects of perceptual learning. Further, mental effort would be continued to be invested to maintain good performance at a later stage of training.

  3. Pupil diameter predicts changes in the exploration-exploitation trade-off: evidence for the adaptive gain theory.

    Science.gov (United States)

    Jepma, Marieke; Nieuwenhuis, Sander

    2011-07-01

    The adaptive regulation of the balance between exploitation and exploration is critical for the optimization of behavioral performance. Animal research and computational modeling have suggested that changes in exploitative versus exploratory control state in response to changes in task utility are mediated by the neuromodulatory locus coeruleus-norepinephrine (LC-NE) system. Recent studies have suggested that utility-driven changes in control state correlate with pupil diameter, and that pupil diameter can be used as an indirect marker of LC activity. We measured participants' pupil diameter while they performed a gambling task with a gradually changing payoff structure. Each choice in this task can be classified as exploitative or exploratory using a computational model of reinforcement learning. We examined the relationship between pupil diameter, task utility, and choice strategy (exploitation vs. exploration), and found that (i) exploratory choices were preceded by a larger baseline pupil diameter than exploitative choices; (ii) individual differences in baseline pupil diameter were predictive of an individual's tendency to explore; and (iii) changes in pupil diameter surrounding the transition between exploitative and exploratory choices correlated with changes in task utility. These findings provide novel evidence that pupil diameter correlates closely with control state, and are consistent with a role for the LC-NE system in the regulation of the exploration-exploitation trade-off in humans.

  4. Refined Synthesis and Characterization of Controlled Diameter, Narrow Size Distribution Microparticles for Aerospace Research Applications

    Science.gov (United States)

    Tiemsin, Pacita I.; Wohl, Christopher J.

    2012-01-01

    Flow visualization using polystyrene microspheres (PSL)s has enabled researchers to learn a tremendous amount of information via particle based diagnostic techniques. To better accommodate wind tunnel researchers needs, PSL synthesis via dispersion polymerization has been carried out at NASA Langley Research Center since the late 1980s. When utilizing seed material for flow visualization, size and size distribution are of paramount importance. Therefore, the work described here focused on further refinement of PSL synthesis and characterization. Through controlled variation of synthetic conditions (chemical concentrations, solution stirring speed, temperature, etc.) a robust, controllable procedure was developed. The relationship between particle size and salt concentration, MgSO4, was identified enabling the determination of PSL diameters a priori. Suggestions of future topics related to PSL synthesis, stability, and size variation are also described.

  5. Size-controlled synthesis of Cu2O nanoparticles via reaction-diffusion

    Science.gov (United States)

    Badr, Layla; Epstein, Irving R.

    2017-02-01

    Copper (I) oxide nanoparticles are synthesized by a simple reaction-diffusion process involving Cu+ ions and sodium hydroxide in gelatin. The mean diameter and the size dispersion of the nanoparticles can be controlled by two experimental parameters, the percent of gelatin in the medium and the hydroxide ion concentration. UV-visible spectroscopy, transmission electron microscopy and X-ray diffraction are used to analyze the size, morphology, and chemical composition of the nanoparticles generated.

  6. Size-Dependent Shifts of Plasmon Resonance in Silver Nanoparticle Films Using Controlled Dissolution

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Kneipp, Katrin

    2014-01-01

    A study of the size dependent blue- and red-shift of the plasmon band of silver nanoparticle films in aqueous solution is reported. A detection scheme, where the particle size is continuously decreased by means of controlled dissolution, while measuring the plasmon band position by UV–vis...... absorption spectroscopy is used. Both blue- and red-shifts of the peak position are observed, depending on the presence of electron donors and/or acceptors in the solution, respectively. A great increase in plasmon shifts for smaller particle sizes (R 10 nm) is demonstrated, which we ascribe...

  7. Simultaneous Size Control of Microcapsule and Its Nanopores Using Polymer Concentration

    Science.gov (United States)

    Jemyung Cha,; Eun Ho Jeong,; Arakawa Takahiro,; Kyung Chun Kim,; Shuich Shoji,; Jeung Sang Go,

    2010-03-01

    Polymeric microcapsules with nanopores are produced using the droplet-based self-assembly of a block copolymer in the microfluidic channel. Differently from the conventional wise, the sizes of the microcapsule and its nanopores are controlled by changing the concentration of the block copolymer dissolved in an organic solvent. The increase in the polymer concentration shows the increase in the size of the microcapsule and the decrease of the size and number of the nanopores. Also, to obtain the optimal morphology of the nanopores in the microcapsule, the removal process of a surfactant is newly developed by using a microporous metal mesh.

  8. Size-controlled fluorescent nanodiamonds: a facile method of fabrication and color-center counting.

    Science.gov (United States)

    Mahfouz, Remi; Floyd, Daniel L; Peng, Wei; Choy, Jennifer T; Loncar, Marko; Bakr, Osman M

    2013-12-07

    We present a facile method for the production of fluorescent diamond nanocrystals (DNCs) of different sizes and efficiently quantify the concentration of emitting defect color centers (DCCs) of each DNC size. We prepared the DNCs by ball-milling commercially available micrometer-sized synthetic (high pressure, high temperature (HPHT)) diamonds and then separated the as-produced DNCs by density gradient ultracentrifugation (DGU) into size-controlled fractions. A protocol to enhance the uniformity of the nitrogen-vacancy (NV) centers in the diamonds was devised by depositing the DNCs as a dense monolayer on amino-silanized silicon substrates and then subjecting the monolayer to He(+) beam irradiation. Using a standard confocal setup, we analyzed the average number of NV centers per crystal, and obtained a quantitative relationship between the DNC particle size and the NV number per crystal. This relationship was in good agreement with results from previous studies that used more elaborate setups. Our findings suggest that nanocrystal size separation by DGU may be used to control the number of defects per nanocrystal. The efficient approaches described herein to control and quantify DCCs are valuable to researchers as they explore applications for color centers and new strategies to create them.

  9. Size-controlled fluorescent nanodiamonds: a facile method of fabrication and color-center counting

    Science.gov (United States)

    Mahfouz, Remi; Floyd, Daniel L.; Peng, Wei; Choy, Jennifer T.; Loncar, Marko; Bakr, Osman M.

    2013-11-01

    We present a facile method for the production of fluorescent diamond nanocrystals (DNCs) of different sizes and efficiently quantify the concentration of emitting defect color centers (DCCs) of each DNC size. We prepared the DNCs by ball-milling commercially available micrometer-sized synthetic (high pressure, high temperature (HPHT)) diamonds and then separated the as-produced DNCs by density gradient ultracentrifugation (DGU) into size-controlled fractions. A protocol to enhance the uniformity of the nitrogen-vacancy (NV) centers in the diamonds was devised by depositing the DNCs as a dense monolayer on amino-silanized silicon substrates and then subjecting the monolayer to He+ beam irradiation. Using a standard confocal setup, we analyzed the average number of NV centers per crystal, and obtained a quantitative relationship between the DNC particle size and the NV number per crystal. This relationship was in good agreement with results from previous studies that used more elaborate setups. Our findings suggest that nanocrystal size separation by DGU may be used to control the number of defects per nanocrystal. The efficient approaches described herein to control and quantify DCCs are valuable to researchers as they explore applications for color centers and new strategies to create them.

  10. Control of body size in C. elegans dependent on food and insulin/IGF-1 signal.

    Science.gov (United States)

    So, Shuhei; Miyahara, Kohji; Ohshima, Yasumi

    2011-06-01

    The body size of an organism is governed by genetic and environmental factors. As an environmental factor, food appears to be the most important for body size control in animals. C. elegans worms are usually grown on an E. coli strain OP50. We show that the wild-type worms fed on another E. coli strain HB101 grow 1.6 times as large as those fed on OP50. The regression line representing the relationship between the sizes of worms grown on each food for over 30 mutants was drawn, indicating that small mutants tend to be more affected by the change in food. Mutants for the DAF-2 insulin/IGF-1 receptor and downstream SGK-1, a homolog of the serum- and glucocorticoid-inducible kinase, grow less or little larger on HB101, indicating control of body size by these factors. Results on the suppression of mutations in these factors by a mutation in the DAF-16/FOXO transcription factor indicate both DAF-16-dependent and DAF-16-independent control. Furthermore, we show that the food-dependent body size change is because of a change in cell size that is closely related to the protein content per cell.

  11. Size-controlled flow synthesis of gold nanoparticles using a segmented flow microfluidic platform.

    Science.gov (United States)

    Cabeza, Victor Sebastian; Kuhn, Simon; Kulkarni, Amol A; Jensen, Klavs F

    2012-05-01

    Segmented flow is often used in the synthesis of nanomaterials to achieve narrow particle size distribution. The narrowness of the distribution is commonly attributed to the reduced dispersion associated with segmented flows. On the basis of the analysis of flow fields and the resulting particle size distribution, we demonstrate that it is the slip velocity between the two fluids and internal mixing in the continuous-phase slugs that govern the nature of the particle size distribution. The reduction in the axial dispersion has less impact on particle growth and hence on the particle size distribution. Synthesis of gold nanoparticles from HAuCl(4) with rapid reduction by NaBH(4) serves as a model system. Rapid reduction yields gold nuclei, which grow by agglomeration, and it is controlled by the interaction of the nuclei with local flow. Thus, the difference in the physical properties of the two phases and the inlet flow rates ultimately control the particle growth. Hence, a careful choice of continuous and dispersed phases is necessary to control the nanoparticle size and size distribution.

  12. Size-controlled fluorescent nanodiamonds: A facile method of fabrication and color-center counting

    KAUST Repository

    Mahfouz, Remi

    2013-01-01

    We present a facile method for the production of fluorescent diamond nanocrystals (DNCs) of different sizes and efficiently quantify the concentration of emitting defect color centers (DCCs) of each DNC size. We prepared the DNCs by ball-milling commercially available micrometer-sized synthetic (high pressure, high temperature (HPHT)) diamonds and then separated the as-produced DNCs by density gradient ultracentrifugation (DGU) into size-controlled fractions. A protocol to enhance the uniformity of the nitrogen-vacancy (NV) centers in the diamonds was devised by depositing the DNCs as a dense monolayer on amino-silanized silicon substrates and then subjecting the monolayer to He+ beam irradiation. Using a standard confocal setup, we analyzed the average number of NV centers per crystal, and obtained a quantitative relationship between the DNC particle size and the NV number per crystal. This relationship was in good agreement with results from previous studies that used more elaborate setups. Our findings suggest that nanocrystal size separation by DGU may be used to control the number of defects per nanocrystal. The efficient approaches described herein to control and quantify DCCs are valuable to researchers as they explore applications for color centers and new strategies to create them. © 2013 The Royal Society of Chemistry.

  13. Sizing Up Peers: Adolescent Girls’ Weight Control and Social Comparison in the School Context *

    Science.gov (United States)

    Mueller, Anna S.; Pearson, Jennifer; Muller, Chandra; Frank, Kenneth; Turner, Alyn

    2014-01-01

    Using the National Longitudinal Study of Adolescent Health and multi-level modeling, we examine the role of social comparison with schoolmates in adolescent girls’ weight control. Specifically, we focus on how girls’ own weight control is influenced by the body sizes and weight-control behaviors of their schoolmates. Our findings suggest that comparisons with similar others (in this case, girls of a similar body size) appears to have the strongest association with individual girls’ reports of trying to lose weight. For example, the odds than an overweight girl is engaged in weight control increases substantially when many overweight girls in her school are also trying to lose weight. This study highlights how schools play an important role in shaping girls’ decisions to practice weight control and demonstrates how social comparison theory improves our understanding of how health behaviors are linked to social contexts. PMID:20420295

  14. Blue and Red Light-Evoked Pupil Responses in Photophobic Subjects with TBI.

    Science.gov (United States)

    Yuhas, Phillip T; Shorter, Patrick D; McDaniel, Catherine E; Earley, Michael J; Hartwick, Andrew T E

    2017-01-01

    Photophobia is a common symptom in individuals suffering from traumatic brain injury (TBI). Recent evidence has implicated blue light-sensitive intrinsically photosensitive retinal ganglion cells (ipRGCs) in contributing to the neural circuitry mediating photophobia in migraine sufferers. The goal of this work is to test the hypothesis that ipRGC function is altered in TBI patients with photophobia by assessing pupillary responses to blue and red light. Twenty-four case participants (mean age 43.3; 58% female), with mild TBI and self-reported photophobia, and 12 control participants (mean age 42.6; 58% female) were in this study. After 10 minutes of dark adaptation, blue (470 nm, 1 × 10 phots/s/cm) and red (625 nm, 7 × 10 phots/s/cm) flashing (0.1 Hz) light stimuli were delivered for 30 seconds to the dilated left eye while the right pupil was recorded. The amplitude of normalized pupil fluctuation (constriction and dilation) was quantified using Fourier fast transforms. In both case and control participants, the amplitude of pupil fluctuation was significantly less for the blue light stimuli as compared to the red light stimuli, consistent with a contribution of ipRGCs to these pupil responses. There was no significant difference in the mean pupil fluctuation amplitudes between the two participant groups, but case participants displayed greater variability in their pupil responses to the blue stimulus. Case and control participants showed robust ipRGC-mediated components in their pupil responses to blue light. The results did not support the hypothesis that ipRGCs are "hypersensitive" to light in TBI participants with photophobia. However, greater pupil response variability in the case subjects suggests that ipRGC function may be more heterogeneous in this group.

  15. Experimental demonstration of binary shaped pupil mask coronagraphs for telescopes with obscured pupils

    CERN Document Server

    Haze, Kanae; Abe, Lyu; Takahashi, Aoi; Kotani, Takayuki; Yamamuro, Tomoyasu

    2016-01-01

    We present the fabrication and experimental demonstration of three free-standing binary shaped pupil mask coronagraphs, which are applicable for telescopes with partially obscured pupils. Three masks, designed to be complementary (labeled Mask-A, Mask-B, and Mask-C), were formed in 5 micron thick nickel. The design of Mask-A is based on a one-dimensional barcode mask. The design principle of Mask-B is similar, but has a smaller inner working angle and a lower contrast than Mask-A. Mask-C is based on a concentric ring mask and provides the widest dark region and a symmetric point spread function. Mask-A and Mask-C were both designed to produce a flexibly tailored dark region (i.e., non-uniform contrast). The contrast was evaluated using a light source comprising a broadband super-luminescent light-emitting diode with a center wavelength of 650 nm, and the measurements were carried out in a large vacuum chamber. Active wavefront control was not applied in this work. The coronagraphic images obtained by experime...

  16. Change in efficiency of aspheric intraocular lenses based on pupil diameter.

    Science.gov (United States)

    Eom, Youngsub; Yoo, Eunjoo; Kang, Su-Yeon; Kim, Hyo-Myung; Song, Jong-Suk

    2013-03-01

    To measure the effect of spherical aberration correction by aspheric intraocular lenses (IOLs) based on pupil diameter, and to determine the minimum pupil diameter for each aspheric IOL. Retrospective cross-sectional study. Eight-six patients (169 eyes) who were implanted with a HOYA AF-1 NY-60 (HOYA Corporation) or Tecnis ZCB00 1-piece IOL (Abbott Medical Optics Inc) were enrolled. Ocular, corneal, and internal spherical aberrations were measured at the 1-month postoperative visit using the Wavefront Analyzer KR-1W (Topcon). Minimum pupil diameter, which is required for each aspheric IOL to be effective, was calculated using a regression equation. The mean value of internal spherical aberration of the Tecnis ZCB00 group (-0.09 ± 0.094 μm) was lower than that of the HOYA NY-60 group (-0.05 ± 0.072 μm) (P = .005). The original negative spherical aberrations of the HOYA NY-60 (-0.18 μm) were measured at a pupil diameter of 5.6 mm, and for the Tecnis ZCB00 (-0.27 μm) at a pupil diameter of 6.1 mm. The aspheric IOL efficiency dropped to 0% when the pupil diameter was 3.47 mm for the Tecnis ZCB00 group and 3.71 mm for the HOYA NY-60 group. When the pupil diameters of patients are smaller than 3.4 mm for the Tecnis ZCB00 and 3.7 mm for the HOYA NY-60, the spherical aberration correction using these aspheric IOLs seems to be ineffective. Approximately 10% of the eyes showed smaller pupil size than the minimum effective diameter under mesopic conditions. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Size-controlled bismuth nanoparticles physically grown by the support of cobalt atomic flux

    Science.gov (United States)

    Lee, Ho Seok; Noh, Jin-Seo

    2016-04-01

    Bi nanoparticle arrays with the almost monodispersity were synthesized using a magnetically assisted physical method. The average size and the overall morphology of Bi nanoparticles could be controlled by the adjustment of several parameters such as relative powers applied to Bi and Co targets, substrate temperature, and growth time. It was disclosed that Bi nanoparticles grow larger at a higher relative power to Bi, higher substrate temperature, and longer growth time, accompanying the deterioration of well-developed faceted structures. This physical method may provide a facile and fast route to achieving quality Bi nanoparticle arrays with a certain extent of size and morphology controllability.

  18. Pupil-linked arousal is driven by decision uncertainty and alters serial choice bias

    Science.gov (United States)

    Urai, Anne E.; Braun, Anke; Donner, Tobias H.

    2017-03-01

    While judging their sensory environments, decision-makers seem to use the uncertainty about their choices to guide adjustments of their subsequent behaviour. One possible source of these behavioural adjustments is arousal: decision uncertainty might drive the brain's arousal systems, which control global brain state and might thereby shape subsequent decision-making. Here, we measure pupil diameter, a proxy for central arousal state, in human observers performing a perceptual choice task of varying difficulty. Pupil dilation, after choice but before external feedback, reflects three hallmark signatures of decision uncertainty derived from a computational model. This increase in pupil-linked arousal boosts observers' tendency to alternate their choice on the subsequent trial. We conclude that decision uncertainty drives rapid changes in pupil-linked arousal state, which shape the serial correlation structure of ongoing choice behaviour.

  19. Secondary school pupils' perceptions of physics

    Science.gov (United States)

    Barmby, Patrick; Defty, Neil

    2006-11-01

    This paper describes the analysis of data collected by Durham University’s YELLIS project, over the period of 1999 to 2004. Included in this data was the degree to which pupils in England at the end of their secondary education ‘liked’ or ‘disliked’ different subjects, and their expected examination grades in these subjects. The authors’ study focused on the perceptions of pupils in the science subjects of biology, chemistry and physics. Using the available data, they were able to analyse the perceptions of a large number of pupils (e.g. 9827 pupils in 2004) who took examinations in the separate sciences. The study found that physics was perceived as the least popular science, particularly by female pupils. We also found that the expected grade in a particular science subject correlated quite strongly (Spearman’s rho of around 0.5) with the liking of that subject. These expected grades were found to be the lowest in physics, again particularly for female pupils. The authors therefore concluded that in order to redress the gender imbalance in physics, they need to tackle this problem that physics is perceived as difficult by female pupils.

  20. Small- and Medium-Sized Commercial Building Monitoring and Controls Needs: A Scoping Study

    Energy Technology Data Exchange (ETDEWEB)

    Katipamula, Srinivas; Underhill, Ronald M.; Goddard, James K.; Taasevigen, Danny J.; Piette, M. A.; Granderson, J.; Brown, Rich E.; Lanzisera, Steven M.; Kuruganti, T.

    2012-10-31

    Buildings consume over 40% of the total energy consumption in the U.S. A significant portion of the energy consumed in buildings is wasted because of the lack of controls or the inability to use existing building automation systems (BASs) properly. Much of the waste occurs because of our inability to manage and controls buildings efficiently. Over 90% of the buildings are either small-size (<5,000 sf) or medium-size (between 5,000 sf and 50,000 sf); these buildings currently do not use BASs to monitor and control their building systems from a central location. According to Commercial Building Energy Consumption Survey (CBECS), about 10% of the buildings in the U.S. use BASs or central controls to manage their building system operations. Buildings that use BASs are typically large (>100,000 sf). Lawrence Berkeley National Laboratory (LBNL), Oak Ridge National Laboratory (ORNL) and Pacific Northwest National Laboratory (PNNL) were asked by the U.S. Department of Energy’s (DOE’s) Building Technologies Program (BTP) to identify monitoring and control needs for small- and medium-sized commercial buildings and recommend possible solutions. This study documents the needs and solutions for small- and medium-sized buildings.

  1. Two-zone pupil filters

    Science.gov (United States)

    Sheppard, Colin J. R.; Campos, Juan; Escalera, Juan C.; Ledesma, Silvia

    2008-03-01

    The performance of pupil filters consisting of two zones each of constant complex amplitude transmittance is investigated. For filters where the transmittance is real, different classes of potentially useful filter are identified and optimized. These include leaky filters with an inner zone of low amplitude transmittance, pure phase filters with phase change of π, and equal area filters. The first of these minimizes the relative power in the outer rings for a given axial resolution, the second maximizes the Strehl ratio for a given transverse resolution, and the third minimizes the relative power in the outer rings for a given transverse resolution. Complex filters can give an axially shifted maximum in intensity: the performance parameters calculated relative to the true focus are investigated for some different classes of filter, but filters with phase change not equal to π are found to give inferior performance to the real value filters.

  2. Coordination of size-control, reproduction and generational memory in freshwater planarians

    Science.gov (United States)

    Yang, Xingbo; Kaj, Kelson J.; Schwab, David J.; Collins, Eva-Maria S.

    2017-06-01

    Uncovering the mechanisms that control size, growth, and division rates of organisms reproducing through binary division means understanding basic principles of their life cycle. Recent work has focused on how division rates are regulated in bacteria and yeast, but this question has not yet been addressed in more complex, multicellular organisms. We have, over the course of several years, assembled a unique large-scale data set on the growth and asexual reproduction of two freshwater planarian species, Dugesia japonica and Girardia tigrina, which reproduce by transverse fission and succeeding regeneration of head and tail pieces into new planarians. We show that generation-dependent memory effects in planarian reproduction need to be taken into account to accurately capture the experimental data. To achieve this, we developed a new additive model that mixes multiple size control strategies based on planarian size, growth, and time between divisions. Our model quantifies the proportions of each strategy in the mixed dynamics, revealing the ability of the two planarian species to utilize different strategies in a coordinated manner for size control. Additionally, we found that head and tail offspring of both species employ different mechanisms to monitor and trigger their reproduction cycles. Thus, we find a diversity of strategies not only between species but between heads and tails within species. Our additive model provides two advantages over existing 2D models that fit a multivariable splitting rate function to the data for size control: firstly, it can be fit to relatively small data sets and can thus be applied to systems where available data is limited. Secondly, it enables new biological insights because it explicitly shows the contributions of different size control strategies for each offspring type.

  3. Symmetry properties with pupil phase-filters.

    Science.gov (United States)

    Ledesma, Silvia; Campos, J; Escalera, J; Yzuel, M

    2004-05-31

    Pupil filters can modify the three dimensional response of an optical system. In this paper, we study different pupil symmetries that produce a predictable image behavior. We show that different pupil-filters that satisfy certain symmetry conditions can produce axial responses which are either identical or mirror reflected. We also establish the differences in the symmetry properties between amplitude-only filters and phase-only filters. In particular, we are interested in phase filters that produce transverse superresolution with axial superresolution or high depth of focus.

  4. Heteronanojunctions with atomic size control using a lab-on-chip electrochemical approach with integrated microfluidics.

    Science.gov (United States)

    Lunca Popa, P; Dalmas, G; Faramarzi, V; Dayen, J F; Majjad, H; Kemp, N T; Doudin, B

    2011-05-27

    A versatile tool for electrochemical fabrication of heteronanojunctions with nanocontacts made of a few atoms and nanogaps of molecular spacing is presented. By integrating microfluidic circuitry in a lab-on-chip approach, we keep control of the electrochemical environment in the vicinity of the nanojunction and add new versatility for exchanging and controlling the junction's medium. Nanocontacts made of various materials by successive local controlled depositions are demonstrated, with electrical properties revealing sizes reaching a few atoms only. Investigations on benchmark molecular electronics material, trapped between electrodes, reveal the possibility to create nanogaps of size matching those of molecules. We illustrate the interest of a microfluidic approach by showing that exposure of a fabricated molecular junction to controlled high solvent flows can be used as a reliability criterion for the presence of molecular entities in a gap.

  5. Environment friendly approach for size controllable synthesis of biocompatible Silver nanoparticles using diastase.

    Science.gov (United States)

    Maddinedi, Sireesh Babu; Mandal, Badal Kumar; Anna, Kiran Kumar

    2017-01-01

    A green, facile method for the size selective synthesis of silver nanoparticles (AgNPs) using diastase as green reducing and stabilizing agent is reported. The thiol groups present in the diastase are mainly responsible for the rapid reaction rate of silver nanoparticles synthesis. The variation in the size and morphology of AgNPs were studied by changing the pH of diastase. The prepared silver nanoparticles were characterized by using UV-vis, XRD, FTIR, TEM and SAED. The FTIR analysis revealed the stabilization of diastase molecules on the surface of AgNPs. Additionally, in-vitro cytotoxicity experiments concluded that the cytotoxicity of the as-synthesized AgNPs towards mouse fibroblast (3T3) cell lines is dose and size dependent. Furthermore, the present method is an alternative to the traditional chemical methods of size controlled AgNPs synthesis.

  6. Impact Craters on Asteroids: Does Gravity or Strength Control Their Size?

    Science.gov (United States)

    Nolan, Michael C.; Asphaug, Erik; Melosh, H. Jay; Greenberg, Richard

    1996-12-01

    The formation of kilometer-size craters on asteroids is qualitatively different from the formation of meter-size (laboratory- and weapons-scale) craters on Earth. A numerical hydrocode model is used to examine the outcomes of various-size cratering impacts into spheres and half-spaces. A shock wave fractures the target in advance of the crater excavation flow; thus, for impactors larger than 100 m, impacting at typical asteroid impact velocities, target tensile strength is irrelevant to the impact outcome. This result holds whether the target is initially intact or a “rubble pile,” even ignoring the effects of gravity. Because of the shock-induced fracture, crater excavation is controlled by gravity at smaller sizes than would otherwise be predicted. Determining the strength-gravity transition by comparing the physical strength of the material to the force of gravity will not work, because strength is eliminated by the shock wave.

  7. Liquid-Metal Microdroplets Formed Dynamically with Electrical Control of Size and Rate.

    Science.gov (United States)

    Tang, Shi-Yang; Joshipura, Ishan D; Lin, Yiliang; Kalantar-Zadeh, Kourosh; Mitchell, Arnan; Khoshmanesh, Khashayar; Dickey, Michael D

    2016-01-27

    Liquid metal co-injected with electrolyte through a microfluidic flow-focusing orifice forms droplets with diameters and production frequencies controlled in real time by voltage. Applying voltage to the liquid metal controls the interfacial tension via a combination of electrochemistry and electrocapillarity. This simple and effective method can instantaneously tune the size of the microdroplets, which has applications in composites, catalysts, and microsystems.

  8. Developmental control of lateralized neuron size in the nematode Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Lockery Shawn

    2010-12-01

    Full Text Available Abstract Background Nervous systems are generally bilaterally symmetric on a gross structural and organizational level but are strongly lateralized (left/right asymmetric on a functional level. It has been previously noted that in vertebrate nervous systems, symmetrically positioned, bilateral groups of neurons in functionally lateralized brain regions differ in the size of their soma. The genetic mechanisms that control these left/right asymmetric soma size differences are unknown. The nematode Caenorhabditis elegans offers the opportunity to study this question with single neuron resolution. A pair of chemosensory neurons (ASEL and ASER, which are bilaterally symmetric on several levels (projections, synaptic connectivity, gene expression patterns, are functionally lateralized in that they express distinct chemoreceptors and sense distinct chemosensory cues. Results We describe here that ASEL and ASER also differ substantially in size (soma volume, axonal and dendritic diameter, a feature that is predicted to change the voltage conduction properties of the two sensory neurons. This difference in size is not dependent on sensory input or neuronal activity but developmentally programmed by a pathway of gene regulatory factors that also control left/right asymmetric chemoreceptor expression of the two ASE neurons. This regulatory pathway funnels via the DIE-1 Zn finger transcription factor into the left/right asymmetric distribution of nucleoli that contain the rRNA regulator Fibrillarin/FIB-1, a RNA methyltransferase implicated in the non-hereditary immune disease scleroderma, which we find to be essential to establish the size differences between ASEL and ASER. Conclusions Taken together, our findings reveal a remarkable conservation of the linkage of functional lateralization with size differences across phylogeny and provide the first insights into the developmentally programmed regulatory mechanisms that control neuron size lateralities.

  9. A SCARECROW-based regulatory circuit controls Arabidopsis thaliana meristem size from the root endodermis

    NARCIS (Netherlands)

    Moubayidin, Laila; Salvi, Elena; Giustini, Leonardo; Terpstra, Inez; Heidstra, Renze; Costantino, Paolo; Sabatini, Sabrina

    2016-01-01

    Main conclusion: SCARECROW controls Arabidopsis root meristem size from the root endodermis tissue by regulating the DELLA protein RGA that in turn mediates the regulation ofARR1levels at the transition zone.Coherent organ growth requires a fine balance between cell division and cell

  10. Functional polythiophene nanoparticles: Size-controlled electropolymerization and ion selective response

    DEFF Research Database (Denmark)

    Si, P.C.; Chi, Qijin; Li, Z.S.

    2007-01-01

    polymerization to form polymer nanoparticles or clusters by which the size of the polymer nanoparticles can further be controlled electrochemically. The electropolymerization was monitored in situ by scanning tunneling microscopy to unravel the dynamics of the process and possible mechanisms. These are further...

  11. Multiple crown size variables of the upper incisors in patients with supernumerary teeth compared with controls

    NARCIS (Netherlands)

    Khalaf, K.; Smith, R. N.; Elcock, C.; Brook, A. H.

    2009-01-01

    Aims: As part of ongoing studies of the aetiology of dental anomalies the aims of this study were to identify multiple components of tooth size of the upper permanent incisors in 34 patients with supernumerary teeth and to compare them with those in a control group to determine whether the presence

  12. Planning an Authority Control Project at a Medium-Sized University Library.

    Science.gov (United States)

    Zhang, Sha Li

    2001-01-01

    Authority control is a vital part of providing students and faculty with adequate access to collections in university libraries. Small and medium-sized libraries find it challenging to meet rising user expectations and provide adequate access in an online environment through appropriate authority work. A planning process is offered on an authority…

  13. A Robust controller for micro-sized agents: The prescribed performance approach

    NARCIS (Netherlands)

    Denasi, Alper; Misra, Sarthak; Haliyo, S.; Sill, A.; Regnier, S.; Fatikow, S.

    2016-01-01

    Applications such as micromanipulation and minimally invasive surgery can be performed using micro-sized agents. For instance, drug-loaded magnetic micro-/nano- particles can enable targeted drug delivery. Their precise manipulation can be assured using a robust motion controller. In this paper, we

  14. Capabilities and Limitations of Tissue Size Control through Passive Mechanical Forces.

    Directory of Open Access Journals (Sweden)

    Jochen Kursawe

    2015-12-01

    Full Text Available Embryogenesis is an extraordinarily robust process, exhibiting the ability to control tissue size and repair patterning defects in the face of environmental and genetic perturbations. The size and shape of a developing tissue is a function of the number and size of its constituent cells as well as their geometric packing. How these cellular properties are coordinated at the tissue level to ensure developmental robustness remains a mystery; understanding this process requires studying multiple concurrent processes that make up morphogenesis, including the spatial patterning of cell fates and apoptosis, as well as cell intercalations. In this work, we develop a computational model that aims to understand aspects of the robust pattern repair mechanisms of the Drosophila embryonic epidermal tissues. Size control in this system has previously been shown to rely on the regulation of apoptosis rather than proliferation; however, to date little work has been done to understand the role of cellular mechanics in this process. We employ a vertex model of an embryonic segment to test hypotheses about the emergence of this size control. Comparing the model to previously published data across wild type and genetic perturbations, we show that passive mechanical forces suffice to explain the observed size control in the posterior (P compartment of a segment. However, observed asymmetries in cell death frequencies across the segment are demonstrated to require patterning of cellular properties in the model. Finally, we show that distinct forms of mechanical regulation in the model may be distinguished by differences in cell shapes in the P compartment, as quantified through experimentally accessible summary statistics, as well as by the tissue recoil after laser ablation experiments.

  15. Capabilities and Limitations of Tissue Size Control through Passive Mechanical Forces.

    Directory of Open Access Journals (Sweden)

    Jochen Kursawe

    2015-12-01

    Full Text Available Embryogenesis is an extraordinarily robust process, exhibiting the ability to control tissue size and repair patterning defects in the face of environmental and genetic perturbations. The size and shape of a developing tissue is a function of the number and size of its constituent cells as well as their geometric packing. How these cellular properties are coordinated at the tissue level to ensure developmental robustness remains a mystery; understanding this process requires studying multiple concurrent processes that make up morphogenesis, including the spatial patterning of cell fates and apoptosis, as well as cell intercalations. In this work, we develop a computational model that aims to understand aspects of the robust pattern repair mechanisms of the Drosophila embryonic epidermal tissues. Size control in this system has previously been shown to rely on the regulation of apoptosis rather than proliferation; however, to date little work has been done to understand the role of cellular mechanics in this process. We employ a vertex model of an embryonic segment to test hypotheses about the emergence of this size control. Comparing the model to previously published data across wild type and genetic perturbations, we show that passive mechanical forces suffice to explain the observed size control in the posterior (P compartment of a segment. However, observed asymmetries in cell death frequencies across the segment are demonstrated to require patterning of cellular properties in the model. Finally, we show that distinct forms of mechanical regulation in the model may be distinguished by differences in cell shapes in the P compartment, as quantified through experimentally accessible summary statistics, as well as by the tissue recoil after laser ablation experiments.

  16. Particle size tailoring of ursolic acid nanosuspensions for improved anticancer activity by controlled antisolvent precipitation.

    Science.gov (United States)

    Wang, Yancai; Song, Ju; Chow, Shing Fung; Chow, Albert H L; Zheng, Ying

    2015-10-15

    The present study was aimed at tailoring the particle size of ursolic acid (UA) nanosuspension for improved anticancer activity. UA nanosuspensions were prepared by antisolvent precipitation using a four-stream multi-inlet vortex mixer (MIVM) under defined conditions of varying solvent composition, drug feeding concentration or stream flow rate. The resulting products were characterized for particle size and polydispersity. Two of the UA nanosuspensions with mean particle sizes of 100 and 300 nm were further assessed for their in-vitro activity against MCF-7 breast cancer cells using fluorescence microscopy with 4',6-diamidino-2-phenylindole (DAPI) staining, as well as flow cytometry with propidium (PI) staining and with double staining by fluorescein isothiocyanate. It was revealed that the solvent composition, drug feeding concentration and stream flow rate were critical parameters for particle size control of the UA nanosuspensions generated with the MIVM. Specifically, decreasing the UA feeding concentration or increasing the stream flow rate or ethanol content resulted in a reduction of particle size. Excellent reproducibility for nanosuspension production was demonstrated for the 100 and 300 nm UA preparations with a deviation of not more than 5% in particle size from the mean value of three independent batches. Fluorescence microscopy and flow cytometry revealed that these two different sized UA nanosuspensions, particularly the 300 nm sample, exhibited a higher anti-proliferation activity against the MCF-7 cells and afforded a larger population of these cells in both early and late apoptotic phases. In conclusion, MIVM is a robust and pragmatic tool for tailoring the particle size of the UA nanosuspension. Particle size appears to be a critical determinant of the anticancer activity of the UA nanoparticles.

  17. Controlling the Pore Size of Mesoporous Carbon Thin Films through Thermal and Solvent Annealing.

    Science.gov (United States)

    Zhou, Zhengping; Liu, Guoliang

    2017-02-02

    Herein an approach to controlling the pore size of mesoporous carbon thin films from metal-free polyacrylonitrile-containing block copolymers is described. A high-molecular-weight poly(acrylonitrile-block-methyl methacrylate) (PAN-b-PMMA) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The authors systematically investigate the self-assembly behavior of PAN-b-PMMA thin films during thermal and solvent annealing, as well as the pore size of mesoporous carbon thin films after pyrolysis. The as-spin-coated PAN-b-PMMA is microphase-separated into uniformly spaced globular nanostructures, and these globular nanostructures evolve into various morphologies after thermal or solvent annealing. Surprisingly, through thermal annealing and subsequent pyrolysis of PAN-b-PMMA into mesoporous carbon thin films, the pore size and center-to-center spacing increase significantly with thermal annealing temperature, different from most block copolymers. In addition, the choice of solvent in solvent annealing strongly influences the block copolymer nanostructure and the pore size of mesoporous carbon thin films. The discoveries herein provide a simple strategy to control the pore size of mesoporous carbon thin films by tuning thermal or solvent annealing conditions, instead of synthesizing a series of block copolymers of various molecular weights and compositions.

  18. Single-walled carbon nanotubes of controlled diameter and bundle size and their field emission properties.

    Science.gov (United States)

    Zhang, Liang; Balzano, Leandro; Resasco, Daniel E

    2005-08-04

    Field emission studies were conducted on as-produced CoMoCAT single-walled carbon nanotube/silica composites with controlled nanotube diameter and bundle size. It has been observed that the as-produced nanotube material does not need to be separated from the high-surface area catalyst to be an effective electron emitter. By adjusting the catalytic synthesis conditions, single-walled carbon nanotubes (SWNT) of different diameters and bundle sizes were synthesized. A detailed characterization involving Raman spectroscopy, optical absorption (vis-NIR), SEM, and TEM was conducted to identify the nanotube species present in the different samples. The synthesis reaction temperature was found to affect the nanotube diameter and bundle size in opposite ways; that is, as the synthesis temperature increased the nanotube average diameter became larger, but the bundle size became smaller. A gradual and consistent reduction in the emission onset field was observed as the synthesis temperature increased. It is suggested that the bundle size, more than the nanotube diameter or chirality, determines the field emission characteristics of these composites. This is a clear demonstration that field emission characteristics of SWNT can be controlled by the nanotube synthesis conditions.

  19. Combining Blink, Pupil, and Response Time Measures in a Concealed Knowledge Test

    Directory of Open Access Journals (Sweden)

    Travis eSeymour

    2013-02-01

    Full Text Available The response time (RT based Concealed Knowledge Test (CKT has been shown to accurately detect participants’ knowledge of mock-crime related information. Tests based on ocular measures such as pupil size and blink rate have sometimes resulted in poor classification, or lacked detailed classification analyses. The present study examines the fitness of multiple pupil and blink related responses in the CKT paradigm. To maximize classification efficiency, participants’ concealed knowledge was assessed using both individual test measures and combinations of test measures. Results show that individual pupil-size, pupil-slope, and pre-response blink-rate measures produce efficient classifications. Combining pupil and blink measures yielded more accuracy classifications than individual ocular measures. Although RT-based tests proved efficient, combining RT with ocular measures had little incremental benefit. It is argued that covertly assessing ocular measures during RT-based tests may guard against effective countermeasure use in applied settings. A compound classification procedure was used to categorize individual participants and yielded high hit rates and low false-alarm rates without the need for adjustments between test paradigms or subject populations. We conclude that with appropriate test paradigms and classification analyses, ocular measures may prove as effective as other indices, though additional research is needed.

  20. Size-controlled synthesis of biodegradable nanocarriers for targeted and controlled cancer drug delivery using salting out cation

    Indian Academy of Sciences (India)

    Madasamy Hari Balakrishanan; Mariappan Rajan

    2016-02-01

    Research for synthesis of size-controlled carriers is currently challenging one. In this research paper, a method for size-controlled synthesis of biodegradable nanocarriers is proposed and described. Salting out method is suitable for both hydrophilic and hydrophobic drugs for the encapsulation on carriers. This synthetic method is based on polylactic acid (PLA) and non-ionic carboxymethyl cellulose (CMC) composed by CaCl2 as salting out agent. This method permits size-controlled synthesis of particles between 50 and 400 nm simply by varying the concentration of salting out agents. We have prepared cisplatin (CDDP)-loaded PLA-CMC nanocarriers by salting out method, with varying salting out agent (CaCl2) concentrations as 0.05, 0.2, 0.35 and 0.5 M. The nanocarriers were characterized for their size, surface charge and morphology by atomic force microscope, zeta potential analyser and transmission electron microscope, respectively. The encapsulation efficiency and in-vitro drug-releasing behaviour of the nanocarriers were investigated. The cytotoxicity effect of nanocarriers and drug-loaded nanocarriers was tested against MCF-7 breast cancer cell line.

  1. Syringe and Needle Size, Syringe Type, Vacuum Generation, and Needle Control in Aspiration Procedures

    Science.gov (United States)

    Haseler, Luke J.; Sibbitt, Randy R.; Sibbitt, Wilmer L.; Michael, Adrian A.; Gasparovic, Charles M.; Bankhurst, Arthur D.

    2013-01-01

    Purpose Syringes are used for diagnostic fluid aspiration and fine needle aspiration biopsy (FNA) in interventional procedures. We determined the benefits, disadvantages, and patient safety implications of syringe and needle size on vacuum generation, hand force requirements, biopsy/fluid yield, and needle control during aspiration procedures. Materials and Methods Different sizes (1, 3, 5, 10, and 20 ml) of the conventional syringe and aspirating mechanical safety syringe, the reciprocating procedure device (RPD), were studied. 20 operators performed aspiration procedures with the following outcomes measured: 1) vacuum (Torr), 2) time to vacuum (seconds), 3) hand force to generate vacuum (Torr-cm2), 4) operator difficulty during aspiration, 5) biopsy yield (mg), and 6) operator control of the needle tip position (mm). Results Vacuum increased tissue biopsy yield at all needle diameters (p aspirate, and resulted in significant loss of needle control (pneedle control (pneedle and maximize fluid and tissue yield during aspiration procedures, a two-handed technique and the smallest syringe size adequate for the procedure should be used. If precise needle control or one-handed operation is required, a mechanical safety syringe should be considered. PMID:21057795

  2. Controlled deposition of NIST-traceable nanoparticles as additional size standards for photomask applications

    Science.gov (United States)

    Wang, Jing; Pui, David Y. H.; Qi, Chaolong; Yook, Se-Jin; Fissan, Heinz; Ultanir, Erdem; Liang, Ted

    2008-03-01

    Particle standard is important and widely used for calibration of inspection tools and process characterization and benchmarking. We have developed a method for generating and classifying monodisperse particles of different materials with a high degree of control. The airborne particles are first generated by an electrospray. Then a tandem Differential Mobility Analyzer (TDMA) system is used to obtain monodisperse particles with NIST-traceable sizes. We have also developed a clean and well-controlled method to deposit airborne particles on mask blanks or wafers. This method utilizes electrostatic approach to deposit particles evenly in a desired spot. Both the number of particles and the spot size are well controlled. We have used our system to deposit PSL, silica and gold particles ranging from 30 nm to 125 nm on 193nm and EUV mask blanks. We report the experimental results of using these particles as calibration standards and discuss the dependency of sensitivity on the types of particles and substrate surfaces.

  3. Confining capillary waves to control aerosol droplet size from surface acoustic wave nebulisation

    Science.gov (United States)

    Nazarzadeh, Elijah; Reboud, Julien; Wilson, Rab; Cooper, Jonathan M.

    Aerosols play a significant role in targeted delivery of medication through inhalation of drugs in a droplet form to the lungs. Delivery and targeting efficiencies are mainly linked to the droplet size, leading to a high demand for devices that can produce aerosols with controlled sizes in the range of 1 to 5 μm. Here we focus on enabling the control of the droplet size of a liquid sample nebulised using surface acoustic wave (SAW) generated by interdigitated transducers on a piezoelectric substrate (lithium niobate). The formation of droplets was monitored through a high-speed camera (600,000 fps) and the sizes measured using laser diffraction (Spraytec, Malvern Ltd). Results show a wide droplet size distribution (between 0.8 and 400 μm), while visual observation (at fast frame rates) revealed that the large droplets (>100 μm) are ejected due to large capillary waves (80 to 300 μm) formed at the free surface of liquid due to leakage of acoustic radiation of the SAWs, as discussed in previous literature (Qi et al. Phys Fluids, 2008). To negate this effect, we show that a modulated structure, specifically with feature sizes, typically 200 μm, prevents formation of large capillary waves by reducing the degrees of freedom of the system, enabling us to obtain a mean droplet size within the optimum range for drug delivery (<10 μm). This work was supported by an EPSRC grant (EP/K027611/1) and an ERC Advanced Investigator Award (340117-Biophononics).

  4. Elevator Sizing, Placement, and Control-Relevant Tradeoffs for Hypersonic Vehicles

    Science.gov (United States)

    Dickeson, Jeffrey J.; Rodriguez, Armando A.; Sridharan, Srikanth; Korad, Akshay

    2010-01-01

    Within this paper, control-relevant vehicle design concepts are examined using a widely used 3 DOF (plus flexibility) nonlinear model for the longitudinal dynamics of a generic carrot-shaped scramjet powered hypersonic vehicle. The impact of elevator size and placement on control-relevant static properties (e.g. level-flight trimmable region, trim controls, Angle of Attack (AOA), thrust margin) and dynamic properties (e.g. instability and right half plane zero associated with flight path angle) are examined. Elevator usage has been examine for a class of typical hypersonic trajectories.

  5. Comparative analysis of cells and proteins of pumpkin plants for the control of fruit size.

    Science.gov (United States)

    Nakata, Yumiko; Taniguchi, Go; Takazaki, Shinya; Oda-Ueda, Naoko; Miyahara, Kohji; Ohshima, Yasumi

    2012-09-01

    Common pumpkin plants (Cucurbita maxima) produce fruits of 1-2 kg size on the average, while special varieties of the same species called Atlantic Giant are known to produce a huge fruit up to several hundred kilograms. As an approach to determine the factors controlling the fruit size in C. maxima, we cultivated both AG and control common plants, and found that both the cell number and cell sizes were increased in a large fruit while DNA content of the cell did not change significantly. We also compared protein patterns in the leaves, stems, ripe and young fruits by two-dimensional (2D) gel electrophoresis, and identified those differentially expressed between them with mass spectroscopy. Based on these results, we suggest that factors in photosynthesis such as ribulose-bisphosphate carboxylase, glycolysis pathway enzymes, heat-shock proteins and ATP synthase play positive or negative roles in the growth of a pumpkin fruit. These results provide a step toward the development of plant biotechnology to control fruit size in the future.

  6. Differentiation of human embryonic stem cells into pancreatic endoderm in patterned size-controlled clusters.

    Science.gov (United States)

    Van Hoof, Dennis; Mendelsohn, Adam D; Seerke, Rina; Desai, Tejal A; German, Michael S

    2011-05-01

    Pancreatic β-cells function optimally when clustered in islet-like structures. However, nutrient and oxygen deprivation limits the viability of cells at the core of excessively large clusters. Hence, production of functional β-cells from human embryonic stem cells (hESCs) for patients with diabetes would benefit from the growth and differentiation of these cells in size-controlled aggregates. In this study, we controlled cluster size by seeding hESCs onto glass cover slips patterned by the covalent microcontact-printing of laminin in circular patches of 120 μm in diameter. These were used as substrates to grow and differentiate hESCs first into SOX17-positive/SOX7-negative definitive endoderm, after which many clusters released and formed uniformly sized three-dimensional clusters. Both released clusters and those that remained attached differentiated into HNF1β-positive primitive gut tube-like cells with high efficiency. Further differentiation yielded pancreatic endoderm-like cells that co-expressed PDX1 and NKX6.1. Controlling aggregate size allows efficient production of uniformly-clustered pancreatic endocrine precursors for in vivo engraftment or further in vitro maturation.

  7. Understanding of the size control of biocompatible gold nanoparticles in millifluidic channels.

    Science.gov (United States)

    Jun, Han; Fabienne, Testard; Florent, Malloggi; Coulon, Pierre-Eugene; Nicolas, Menguy; Olivier, Spalla

    2012-11-13

    The size control of gold nanoparticles synthesized in surfactant free water with a continuous flow mode was elucidated and used to produce higher concentration (3 mM) of stabilized gold nanoparticles. The originality of the synthesis was to finely modulate the initial pH of the reducing agent instead of the gold precursor to modify the kinetic of the reaction. The acceleration of the kinetic (~1 s) prevents the modification of the gold precursors ensuring the control of the final size (from 3 to 25 nm) of the nanoparticles with a low polydispersity for aqueous surfactant free solution. The accurate measure of the size distribution by small angle X-ray scattering was combined to the use of a model based on the coupling of nucleation and growth equations together with a progressive injection of monomers. The results on the final state show that the size of the nanoparticles is indeed controlled by the kinetic of reduction of gold atoms. A millifluidic setup equipped with a homemade mixer offers a robust way of rapid mixing to obtain a reproducible production of large amounts of nanoparticles.

  8. Subnanometer Control of Mean Core Size during Mesofluidic Synthesis of Small (D(core) Nanoparticles.

    Science.gov (United States)

    Elliott, Edward W; Haben, Patrick M; Hutchison, James E

    2015-11-03

    A convenient, single-step synthesis is reported that produces ligand-stabilized, water-soluble gold nanoparticles (AuNPs) with subnanometer-level precision of the mean core diameter over a range of 2-9 nm for a series of desired surface chemistries. The synthesis involves the reduction of a Au(III) species with sodium borohydride in the presence of a functionalized alkyl thiosulfate (Bunte salt) to yield thiolate-protected AuNPs. A key advantage of this synthesis is that simply adjusting the pH of the gold salt solution leads to control over the AuNP core size. The speciation of Au(III), and therefore the kinetics for its reduction and the core size produced, depends upon pH. The use of pH as the sole variable to control core size is a more reliable and convenient method than traditional approaches that rely on adjusting the concentrations and ratios of ligand, metal salt, and reducing agent. The average core size increased as the pH was raised for each ligand studied. Because the influence of pH was different for each of the ligands, working curves were plotted for each ligand to identify conditions to synthesize particles with specific, targeted core diameters. Using this approach, reaction conditions can be rapidly optimized using a combination of a mesofluidic reactor and small-angle X-ray scattering (SAXS) size analysis. The use of the mesofluidic reactor was needed to ensure fast mixing given the rapid kinetics for core formation. Using the reactor, it is possible to obtain reproducible sizes across multiple syntheses (size variation) and subnanometer control of the mean core dimensions. The synthetic method demonstrated here provides an attractive alternative to two-step syntheses involving ligand exchange because it is more efficient and eliminates the possibility of nanoparticle core size changes during exchange steps. This approach enables the development of "size ladders" of particles with the same surface chemistry for investigations of structure

  9. Pupil Response to Threat in Trauma-Exposed Individuals With or Without PTSD.

    Science.gov (United States)

    Cascardi, Michele; Armstrong, Davine; Chung, Leeyup; Paré, Denis

    2015-08-01

    An infrequently studied and potentially promising physiological marker for posttraumatic stress disorder (PTSD) is pupil response. This study tested the hypothesis that pupil responses to threat would be significantly larger in trauma-exposed individuals with PTSD compared to those without PTSD. Eye-tracking technology was used to evaluate pupil response to threatening and neutral images. Recruited for participation were 40 trauma-exposed individuals; 40.0% (n = 16) met diagnostic criteria for PTSD. Individuals with PTSD showed significantly more pupil dilation to threat-relevant stimuli compared to the neutral elements (Cohen's d = 0.76), and to trauma-exposed controls (Cohen's d = 0.75). Pupil dilation significantly accounted for 12% of variability in PTSD after time elapsed since most recent trauma, cumulative violence exposure, and trait anxiety were statistically adjusted. The final logistic regression model was associated with 85% of variability in PTSD status and correctly classified 93.8% of individuals with PTSD and 95.8% of those without. Pupil reactivity showed promise as a physiological marker for PTSD.

  10. Relating Pupil Dilation and Metacognitive Confidence during Auditory Decision-Making.

    Science.gov (United States)

    Lempert, Karolina M; Chen, Yu Lin; Fleming, Stephen M

    2015-01-01

    The sources of evidence contributing to metacognitive assessments of confidence in decision-making remain unclear. Previous research has shown that pupil dilation is related to the signaling of uncertainty in a variety of decision tasks. Here we ask whether pupil dilation is also related to metacognitive estimates of confidence. Specifically, we measure the relationship between pupil dilation and confidence during an auditory decision task using a general linear model approach to take into account delays in the pupillary response. We found that pupil dilation responses track the inverse of confidence before but not after a decision is made, even when controlling for stimulus difficulty. In support of an additional post-decisional contribution to the accuracy of confidence judgments, we found that participants with better metacognitive ability - that is, more accurate appraisal of their own decisions - showed a tighter relationship between post-decisional pupil dilation and confidence. Together our findings show that a physiological index of uncertainty, pupil dilation, predicts both confidence and metacognitive accuracy for auditory decisions.

  11. Control of sizes and densities of nano catalysts for nanotube synthesis by plasma breaking method

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J.S.; Umeda, K.; Uchino, K.; Nakashima, H.; Muraoka, K

    2004-03-15

    Sizes and densities of nano catalysts for carbon nanotube synthesis, formed by the plasma breaking method of thin Fe films deposited using pulse laser deposition (PLD) were controlled by the changes of operating parameters. At the best optimum condition, nano catalysts with a density of 1.9x10{sup 15} m{sup -2} and a diameter of about 15 nm were obtained. Carbon nanotubes (CNTs) synthesized on these catalysts were shown to have almost the same size and density as those of the catalysts.

  12. Non-intrusive practitioner pupil detection for unmodified microscope oculars.

    Science.gov (United States)

    Fuhl, Wolfgang; Santini, Thiago; Reichert, Carsten; Claus, Daniel; Herkommer, Alois; Bahmani, Hamed; Rifai, Katharina; Wahl, Siegfried; Kasneci, Enkelejda

    2016-12-01

    Modern microsurgery is a long and complex task requiring the surgeon to handle multiple microscope controls while performing the surgery. Eye tracking provides an additional means of interaction for the surgeon that could be used to alleviate this situation, diminishing surgeon fatigue and surgery time, thus decreasing risks of infection and human error. In this paper, we introduce a novel algorithm for pupil detection tailored for eye images acquired through an unmodified microscope ocular. The proposed approach, the Hough transform, and six state-of-the-art pupil detection algorithms were evaluated on over 4000 hand-labeled images acquired from a digital operating microscope with a non-intrusive monitoring system for the surgeon eyes integrated. Our results show that the proposed method reaches detection rates up to 71% for an error of ≈3% w.r.t the input image diagonal; none of the state-of-the-art pupil detection algorithms performed satisfactorily. The algorithm and hand-labeled data set can be downloaded at:: www.ti.uni-tuebingen.de/perception. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Compatibility of a Diffractive Pupil and Coronagraphic Imaging

    Science.gov (United States)

    Bendek, Eduardo; Belikov, Rusian; Pluzhnyk, Yevgeniy; Guyon, Olivier

    2013-01-01

    Detection and characterization of exo-earths require direct-imaging techniques that can deliver contrast ratios of 10(exp 10) at 100 milliarc-seconds or smaller angular separation. At the same time, astrometric data is required to measure planet masses and can help detect planets and constrain their orbital parameters. To minimize costs, a single space mission can be designed using a high efficiency coronograph to perform direct imaging and a diffractive pupil to calibrate wide-field distortions to enable high precision astrometric measurements. This paper reports the testing of a diffractive pupil on the high-contrast test bed at the NASA Ames Research Center to assess the compatibility of using a diffractive pupil with coronographic imaging systems. No diffractive contamination was found within our detectability limit of 2x10(exp -7) contrast outside a region of 12lambda/D and 2.5x10(exp -6) within a region spanning from 2 to 12lambda/D. Morphology of the image features suggests that no contamination exists even beyond the detectability limit specified or at smaller working angles. In the case that diffractive contamination is found beyond these stated levels, active wavefront control would be able to mitigate its intensity to 10(exp -7) or better contrast.

  14. Adaptive optics with pupil tracking for high resolution retinal imaging.

    Science.gov (United States)

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  15. Epidermal Patterning Genes Impose Non-cell Autonomous Cell Size Determination and have Additional Roles in Root Meristem Size Control

    Institute of Scientific and Technical Information of China (English)

    Christian L?fke; Kai Dünser; Jürgen Kleine-Vehn

    2013-01-01

    The regulation of cellular growth is of vital importance for embryonic and postembryonic patterning. Growth regulation in the epidermis has importance for organ growth rates in roots and shoots, proposing epidermal cells as an interesting model for cellular growth regulation. Here we assessed whether the root epidermis is a suitable model system to address cell size determination. In Arabidopsis thaliana L., root epidermal cells are regularly spaced in neighbouring tricho-(root hair) and atrichoblast (non-hair) cells, showing already distinct cell size regulation in the root meristem. We determined cell sizes in the root meristem and at the onset of cellular elongation, revealing that not only division rates but also cellular shape is distinct in tricho-and atrichoblasts. Intriguingly, epidermal-patterning mutants, failing to define differential vacuolization in neighbouring epidermal cell files, also display non-differential growth. Using these epidermal-patterning mutants, we show that polarized growth behaviour of epidermal tricho-and atrichoblast is interdependent, suggesting non-cell autonomous signals to integrate tissue expansion. Besides the interweaved cell-type-dependent growth mechanism, we reveal an additional role for epidermal patterning genes in root meristem size and organ growth regulation. We conclude that epidermal cells represent a suitable model system to study cell size determination and interdependent tissue growth.

  16. Shape and size controlled synthesis of uniform iron oxide nanocrystals through new non-hydrolytic routes

    Science.gov (United States)

    Li, Wenlu; Lee, Seung Soo; Wu, Jiewei; Hinton, Carl H.; Fortner, John D.

    2016-08-01

    New, non-hydrolytic routes to synthesize highly crystalline iron oxide nanocrystals (8-40 nm, magnetite) are described in this report whereby particle size and morphology were precisely controlled through reactant (precursor, e.g. (FeO(OH)) ratios, co-surfactant and organic additive, and/or reaction time. Particle size, with high monodispersivity (oxide nanocrystals can be reproducibly synthesized through simple one-pot thermal decomposition methods. High resolution transmission electron microscope, x-ray diffraction, and superconducting quantum interference device were used to characterize the size, structure and magnetic properties of the resulting nanocrystals. For aqueous applications, materials synthesized/purified in organic solvents are broadly water dispersible through a variety of phase (aqueous) transfer method(s).

  17. Hydrodynamic size distribution of gold nanoparticles controlled by repetition rate during pulsed laser ablation in water

    Science.gov (United States)

    Menéndez-Manjón, Ana; Barcikowski, Stephan

    2011-02-01

    Most investigations on the laser generation and fragmentation of nanoparticles focus on Feret particle size, although the hydrodynamic size of nanoparticles is of great importance, for example in biotechnology for diffusion in living cells, or in engineering, for a tuned rheology of suspensions. In this sense, the formation and fragmentation of gold colloidal nanoparticles using femtosecond laser ablation at variable pulse repetition rates (100-5000 Hz) in deionized water were investigated through their plasmon resonance and hydrodynamic diameter, measured by Dynamic Light Scattering. The increment of the repetition rate does not influence the ablation efficiency, but produces a decrease of the hydrodynamic diameter and blue-shift of the plasmon resonance of the generated gold nanoparticles. Fragmentation, induced by inter-pulse irradiation of the colloids was measured online, showing to be more effective low repetition rates. The pulse repetition rate is shown to be an appropriate laser parameter for hydrodynamic size control of nanoparticles without further influence on the production efficiency.

  18. Size-controllable synthesis and bandgap modulation of single-layered RF-sputtered bismuth nanoparticles

    Science.gov (United States)

    Wu, Bin-Kun; Chern, Ming-Yau; Lee, Hsin-Yen

    2014-05-01

    We here report a simple and efficient method to grow single-layer bismuth nanoparticles (BiNPs) with various sizes on glass substrates. Optimal conditions were found to be 200°C and 0.12 W/cm2 at a growth rate of 6 Å/s, with the deposition time around 40 s. Scanning electron microscope (SEM) images were used to calculate the particle size distribution statistics, and high-resolution X-ray diffraction (XRD) patterns were used to examine the chemical interactions between BiNPs and the substrates. By measuring the transmission spectra within the range of 300 to 1,000 nm, we found that the optical bandgap can be modulated from 0.45 to 2.63 eV by controlling the size of these BiNPs. These interesting discoveries offer an insight to explore the dynamic nature of nanoparticles.

  19. Shape-controlled synthesis of highly monodisperse and small size gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    FU YunZhi; DU YuKou; YANG Ping; LI JinRu; JIANG Long

    2007-01-01

    We describe here that fine control of nanoparticle shape and size can be achieved by systematic variation of experimental parameters in the seeded growth procedure in aqueous solution. Cubic and spherical gold nanoparticles are obtained respectively. In particularly, the Au cubes are highly monodisperse in 33±2 nm diameter. The experimental methods involve the preparation of Au seed particles and the subsequent addition of an appropriate quantity of Au seed solution to the aqueous growth solutions containing desired quantities of CTAB and ascorbic acid (AA). Here, AA is a weak reducing agent and CTAB is not only a stable agent for nanoparticles but also an inductive agent for leading increase in the face of nanoparticle. Ultraviolet visible spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) are used to characterize the nanoparticles. The results show that the different size gold nanoparticles displayed high size homogenous distribution and formed mono-membrane at the air/solid interface.

  20. Controlling DNA Bundle Size and Spatial Arrangement in Self-assembled Arrays on Superhydrophobic Surface

    Institute of Scientific and Technical Information of China (English)

    Gabriele Ciasca; Luca Businaro; Marco De Spirito; Massimiliano Papi; Valentina Palmieri; Michela Chiarpotto; Simone Di Claudio; Adele De Ninno; Ennio Giovine; Gaetano Campi; Annamaria Gerardino

    2015-01-01

    The use of superhydrophobic surfaces (SHSs) is now emerging as an attractive platform for the realization of one-dimensional (1D) nanostructures with potential applications in many nanotechnological and biotechnological fields. To this purpose, a strict control of the nanostructures size and their spatial arrangement is highly required. However, these parameters may be strongly dependent on the complex evaporation dynamics of the sessile droplet on the SHS. In this work, we investigated the effect of the evaporation dynamics on the size and the spatial arrangement of self-assembled 1D DNA bundles. Our results reveal that different arrangements and bundle size distributions may occur depending on droplet evaporation stage. These results contribute to elucidate the formation mechanism of 1D nanostructures on SHSs.

  1. Size controlled biogenic silver nanoparticles as antibacterial agent against isolates from HIV infected patients

    Science.gov (United States)

    Suganya, K. S. Uma; Govindaraju, K.; Kumar, V. Ganesh; Dhas, T. Stalin; Karthick, V.; Singaravelu, G.; Elanchezhiyan, M.

    2015-06-01

    Silver nanoparticles (AgNPs) are synthesized using biological sources due to its high specificity in biomedical applications. Herein, we report the size and shape controlled synthesis of AgNPs using the aqueous extract of blue green alga, Spirulina platensis. Size, shape and elemental composition of AgNPs were characterized using UV-vis spectroscopy, Fluorescence spectroscopy, FT-IR (Fourier Transform-Infrared Spectroscopy), FT-RS (Fourier Transform-Raman Spectroscopy), SEM-EDAX (Scanning Electron Microscopy-Energy Dispersive X-ray analysis) and HR-TEM (High Resolution Transmission Electron Microscopy). AgNPs were stable, well defined and monodispersed (spherical) with an average size of 6 nm. The synthesized AgNPs were tested for its antibacterial potency against isolates obtained from HIV patients.

  2. Enhanced Immunostimulating Activity of Lactobacilli-Mimicking Materials by Controlling Size.

    Science.gov (United States)

    Nagahama, Koji; Kumano, Takayuki; Nakagawa, Yuichi; Oyama, Naho; Tsuji, Hirokazu; Moriyama, Kaoru; Shida, Kan; Nomoto, Koji; Chiba, Katsuyoshi; Koumoto, Kazuya; Matsui, Jun

    2015-08-19

    The design and synthesis of materials capable of activating the immune system in a safe manner is of great interest in immunology and related fields. Lactobacilli activate the innate immune system of a host when acting as probiotics. Here, we constructed lactobacilli-mimicking materials in which polysaccharide-peptidoglycan complexes (PS-PGs) derived from lactobacilli were covalently conjugated to the surfaces of polymeric microparticles with a wide variety of sizes, ranging from 200 nm to 3 μm. The artificial lactobacilli successfully stimulated macrophages without cytotoxicity. Importantly, we found that the size of artificial lactobacilli strongly influenced their immunostimulating activities, and that artificial lactobacilli of 1 μm exhibited 10-fold higher activity than natural lactobacilli. One major advantage of the artificial lactobacilli is facile control of size, which cannot be changed in natural lactobacilli. These findings provide new insights into the design of materials for immunology as well as the molecular biology of lactobacillus.

  3. Size and morphology controlled NiSe nanoparticles as efficient catalyst for the reduction reactions

    Science.gov (United States)

    Subbarao, Udumula; Marakatti, Vijaykumar S.; Amshumali, Mungalimane K.; Loukya, B.; Singh, Dheeraj Kumar; Datta, Ranjan; Peter, Sebastian C.

    2016-12-01

    Facile and efficient ball milling and polyol methods were employed for the synthesis of nickel selenide (NiSe) nanoparticle. The particle size of the NiSe nanoparticle has been controlled mechanically by varying the ball size in the milling process. The role of the surfactants in the formation of various morphologies was studied. The compounds were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The efficiency of the NiSe nanoparticle as a catalyst was tested for the reduction of para-nitroaniline (PNA) to para-phenyldiamine (PPD) and para-nitrophenol (PNP) to para-aminophenol (PAP) using NaBH4 as the reducing agent. Particle size, morphology and the presence of surfactant played a crucial role in the reduction process.

  4. Controlling Pore Size and its Distribution of γ-Al2O3 Nanofiltration Membranes

    Institute of Scientific and Technical Information of China (English)

    Rong Chun XIONG; Xiao Dong LEI; Gang WEI

    2003-01-01

    The preparation process of γ-Al2O3 nanofiltration membranes were studied by N2absorption and desorption test and retention rate vs thickness gradient curve method. It was foundthat template and thermal treatment were key factors for controlling pore size and its distribution.Under the optimized experimental conditions, the BJH (Barret-Joyner-Halenda) desorption averagepore diameter, BJH desorption cumulative volume of pores and BET (Brunauer-Emmett-Teller)surface area of obtained membranes were about 3.9 nm, 0.33 cm3/g and 245 m2/g respectively, thepore size distribution was very narrow. Pore size decreased with the increasing of thickness andno evident change after the dense top layer was formed. The optimum thickness can becontrolled by retention rate vs thickness gradient curve method.

  5. User-centered evaluation of handle shape and size and input controls for a neutron detector.

    Science.gov (United States)

    Herring, Scarlett R; Castillejos, Pamela; Hallbeck, M Susan

    2011-11-01

    Current neutron detectors are big, heavy, difficult to use and are not ergonomically designed. Good handle design and easy to use control mechanisms are imperative for comfort, usability and accuracy for hand-held tools. Two studies were performed to assess these factors; Study I explored handle design (shape and size) preference and Study II evaluated the effects of control mechanisms, device orientations and word orientation on performance time. According to research findings, the recommended handle perimeter is 11 cm with a diameter range of 3.5-4.0 cm. These results demonstrated that as the handle perimeter decreased the handle becomes less preferred by first responders when using layered gloves. For control type, the fastest performance time was found with vertical push buttons and a vertical word orientation. These objective results matched the subjective results, which showed that the most preferred controller was a vertical push button control.

  6. Size-Controlled Synthesis of Sub-10 nm PtNi3 Alloy Nanoparticles and their Unusual Volcano-Shaped Size Effect on ORR Electrocatalysis.

    Science.gov (United States)

    Gan, Lin; Rudi, Stefan; Cui, Chunhua; Heggen, Marc; Strasser, Peter

    2016-06-01

    Dealloyed Pt bimetallic core-shell catalysts derived from low-Pt bimetallic alloy nanoparticles (e.g, PtNi3 ) have recently shown unprecedented activity and stability on the cathodic oxygen reduction reaction (ORR) under realistic fuel cell conditions and become today's catalyst of choice for commercialization of automobile fuel cells. A critical step toward this breakthrough is to control their particle size below a critical value (≈10 nm) to suppress nanoporosity formation and hence reduce significant base metal (e.g., Ni) leaching under the corrosive ORR condition. Fine size control of the sub-10 nm PtNi3 nanoparticles and understanding their size dependent ORR electrocatalysis are crucial to further improve their ORR activity and stability yet still remain unexplored. A robust synthetic approach is presented here for size-controlled PtNi3 nanoparticles between 3 and 10 nm while keeping a constant particle composition and their size-selected growth mechanism is studied comprehensively. This enables us to address their size-dependent ORR activities and stabilities for the first time. Contrary to the previously established monotonic increase of ORR specific activity and stability with increasing particle size on Pt and Pt-rich bimetallic nanoparticles, the Pt-poor PtNi3 nanoparticles exhibit an unusual "volcano-shaped" size dependence, showing the highest ORR activity and stability at the particle sizes between 6 and 8 nm due to their highest Ni retention during long-term catalyst aging. The results of this study provide important practical guidelines for the size selection of the low Pt bimetallic ORR electrocatalysts with further improved durably high activity.

  7. Distributed Active Traction Control System Applied to the RoboCup Middle Size League

    Directory of Open Access Journals (Sweden)

    José Almeida

    2013-10-01

    Full Text Available This work addresses the problem of traction control in mobile wheeled robots in the particular case of the RoboCup Middle Size League (MSL. The slip control problem is formulated using simple friction models for ISePorto Team Robots with a differential wheel configuration. Traction was also characterized experimentally in the MSL scenario for relevant game events. This work proposes a hierarchical traction control architecture which relies on local slip detection and control at each wheel, with relevant information being relayed to a higher level responsible for global robot motion control. A dedicated one axis control embedded hardware subsystem allowing complex local control, high frequency current sensing and odometric information procession was developed. This local axis control board is integrated in a distributed system using CAN bus communications. The slipping observer was implemented in the axis control hardware nodes integrated in the ISePorto Robots and was used to control and detect loss of traction. An external vision system was used to perform a qualitative analysis of the slip detection and observer performance results are presented.

  8. Evaluating the control software for CTA in a medium size telescope prototype

    Science.gov (United States)

    Oya, I.; Behera, B.; Birsin, E.; Koeppel, H.; Melkumyan, D.; Schmidt, T.; Schwanke, U.; Wegner, P.; Wiesand, S.; Winde, M.; Consortium, CTA

    2012-12-01

    CTA (Cherenkov Telescope Array) is one of the largest ground-based astronomy projects being pursued and will be the largest facility for ground-based γ-ray observations ever built. CTA will consist of two arrays (one in the Northern hemisphere and one in the Southern hemisphere) composed of telescopes of several sizes. A prototype for the Medium Size Telescope (MST) of a diameter of 12 m will be installed in Berlin by the end of 2012. This MST prototype will be composed of the mechanical structure, drive system and mirror facets mounted with powered actuators to enable active control. Five Charge-Coupled Device (CCD) cameras and a weather station will allow the measurement of the performance of the instrument. The Atacama Large Millimeter/submillimeter Array (ALMA) Common Software (ACS) distributed control framework is currently being considered by the CTA consortium to serve as the array control middleware. In order to evaluate the ACS software, it has been decided to implement an ACS-based readout and control system for the MST prototype. The design of the control software is following the concepts and tools under evaluation within the CTA consortium, like the use of a Unified Modeling Language (UML) based code generation framework for ACS component modeling, and the use of OPen Connectivity-Unified Architecture (OPC UA) for hardware access. In this contribution, the progress in the implementation of the control system for this CTA prototype telescope is described.

  9. Facile fabrication of BiVO4 nanofilms with controlled pore size and their photoelectrochemical performances

    Science.gov (United States)

    Feng, Chenchen; Jiao, Zhengbo; Li, Shaopeng; Zhang, Yan; Bi, Yingpu

    2015-12-01

    We demonstrate a facile method for the rational fabrication of pore-size controlled nanoporous BiVO4 photoanodes, and confirmed that the optimum pore-size distributions could effectively absorb visible light through light diffraction and confinement functions. Furthermore, in situ X-ray photoelectron spectroscopy (XPS) reveals more efficient photoexcited electron-hole separation than conventional particle films, induced by light confinement and rapid charge transfer in the inter-crossed worm-like structures.We demonstrate a facile method for the rational fabrication of pore-size controlled nanoporous BiVO4 photoanodes, and confirmed that the optimum pore-size distributions could effectively absorb visible light through light diffraction and confinement functions. Furthermore, in situ X-ray photoelectron spectroscopy (XPS) reveals more efficient photoexcited electron-hole separation than conventional particle films, induced by light confinement and rapid charge transfer in the inter-crossed worm-like structures. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06584d

  10. On the repeated measures designs and sample sizes for randomized controlled trials.

    Science.gov (United States)

    Tango, Toshiro

    2016-04-01

    For the analysis of longitudinal or repeated measures data, generalized linear mixed-effects models provide a flexible and powerful tool to deal with heterogeneity among subject response profiles. However, the typical statistical design adopted in usual randomized controlled trials is an analysis of covariance type analysis using a pre-defined pair of "pre-post" data, in which pre-(baseline) data are used as a covariate for adjustment together with other covariates. Then, the major design issue is to calculate the sample size or the number of subjects allocated to each treatment group. In this paper, we propose a new repeated measures design and sample size calculations combined with generalized linear mixed-effects models that depend not only on the number of subjects but on the number of repeated measures before and after randomization per subject used for the analysis. The main advantages of the proposed design combined with the generalized linear mixed-effects models are (1) it can easily handle missing data by applying the likelihood-based ignorable analyses under the missing at random assumption and (2) it may lead to a reduction in sample size, compared with the simple pre-post design. The proposed designs and the sample size calculations are illustrated with real data arising from randomized controlled trials.

  11. Arabidopsis haiku mutants reveal new controls of seed size by endosperm.

    Science.gov (United States)

    Garcia, Damien; Saingery, Virginie; Chambrier, Pierre; Mayer, Ulrike; Jürgens, Gerd; Berger, Frédéric

    2003-04-01

    In flowering plants, maternal seed integument encloses the embryo and the endosperm, which are both derived from double fertilization. Although the development of these three components must be coordinated, we have limited knowledge of mechanisms involved in such coordination. The endosperm may play a central role in these mechanisms as epigenetic modifications of endosperm development, via imbalance of dosage between maternal and paternal genomes, affecting both the embryo and the integument. To identify targets of such epigenetic controls, we designed a genetic screen in Arabidopsis for mutants that phenocopy the effects of dosage imbalance in the endosperm. The two mutants haiku 1 and haiku 2 produce seed of reduced size that resemble seed with maternal excess in the maternal/paternal dosage. Homozygous haiku seed develop into plants indistinguishable from wild type. Each mutation is sporophytic recessive, and double-mutant analysis suggests that both mutations affect the same genetic pathway. The endosperm of haiku mutants shows a premature arrest of increase in size that causes precocious cellularization of the syncytial endosperm. Reduction of seed size in haiku results from coordinated reduction of endosperm size, embryo proliferation, and cell elongation of the maternally derived integument. We present further evidence for a control of integument development mediated by endosperm-derived signals.

  12. Granule size control and targeting in pulsed spray fluid bed granulation.

    Science.gov (United States)

    Ehlers, Henrik; Liu, Anchang; Räikkönen, Heikki; Hatara, Juha; Antikainen, Osmo; Airaksinen, Sari; Heinämäki, Jyrki; Lou, Honxiang; Yliruusi, Jouko

    2009-07-30

    The primary aim of the study was to investigate the effects of pulsed liquid feed on granule size. The secondary aim was to increase knowledge of this technique in granule size targeting. Pulsed liquid feed refers to the pump changing between on- and off-positions in sequences, called duty cycles. One duty cycle consists of one on- and off-period. The study was performed with a laboratory-scale top-spray fluid bed granulator with duty cycle length and atomization pressure as studied variables. The liquid feed rate, amount and inlet air temperature were constant. The granules were small, indicating that the powder has only undergone ordered mixing, nucleation and early growth. The effect of atomizing pressure on granule size depends on inlet air relative humidity, with premature binder evaporation as a reason. The duty cycle length was of critical importance to the end product attributes, by defining the extent of intermittent drying and rewetting. By varying only the duty cycle length, it was possible to control granule nucleation and growth, with a wider granule size target range in increased relative humidity. The present study confirms that pulsed liquid feed in fluid bed granulation is a useful tool in end product particle size targeting.

  13. Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

    Science.gov (United States)

    Lio, Daniel; Yeo, David; Xu, Chenjie

    2016-01-01

    Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %.

  14. Novel approach to fabricate keratin sponge scaffolds with controlled pore size and porosity.

    Science.gov (United States)

    Katoh, Kazunori; Tanabe, Toshizumi; Yamauchi, Kiyoshi

    2004-08-01

    A compression-molding/particulate-leaching (CM/PL) method was developed to fabricate S-sulfo keratin sponges with the controlled pore size and porosity. The S-sulfo keratin was extracted from wool and was then spray-dried to give S-sulfo keratin powder. The S-sulfo keratin powder mixed with urea in advance was compression-molded together with the sieved NaCl particulates above the melting temperature of urea. The following removal of the salts and urea in water created the sponges composed of interconnected pores and the continuous S-sulfo keratin matrix. The S-sulfo keratin sponges were strong enough to handle and water-insoluble. By contrast, the sponges prepared without urea were very fragile and readily collapsed, because most of S-sulfo keratin matrix remained powdery. The pore size was in good accordance with the size of the salts, indicating that the pores were formed by leaching-out the salts. The S-sulfo keratin sponges with the regulated sizes of pores (<100, 100-300 and 300-500 microm) were fabricated, all of which had more than 90% of the porosity. Thus, CM/PL method is able to give the S-sulfo keratin sponge with the desired pore size and porosity, which might be a good scaffold for the cells in tissue engineering.

  15. Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping

    KAUST Repository

    Wang, Feng

    2010-02-25

    Doping is a widely applied technological process in materials science that involves incorporating atoms or ions of appropriate elements into host lattices to yield hybrid materials with desirable properties and functions. For nanocrystalline materials, doping is of fundamental importance in stabilizing a specific crystallographic phase, modifying electronic properties, modulating magnetism as well as tuning emission properties. Here we describe a material system in which doping influences the growth process to give simultaneous control over the crystallographic phase, size and optical emission properties of the resulting nanocrystals. We show that NaYF 4 nanocrystals can be rationally tuned in size (down to ten nanometres), phase (cubic or hexagonal) and upconversion emission colour (green to blue) through use of trivalent lanthanide dopant ions introduced at precisely defined concentrations. We use first-principles calculations to confirm that the influence of lanthanide doping on crystal phase and size arises from a strong dependence on the size and dipole polarizability of the substitutional dopant ion. Our results suggest that the doping-induced structural and size transition, demonstrated here in NaYF 4 upconversion nanocrystals, could be extended to other lanthanide-doped nanocrystal systems for applications ranging from luminescent biological labels to volumetric three-dimensional displays. © 2010 Macmillan Publishers Limited. All rights reserved.

  16. The TOR Signaling Pathway in Spatial and Temporal Control of Cell Size and Growth

    Directory of Open Access Journals (Sweden)

    Suam Gonzalez

    2017-06-01

    Full Text Available Cell size is amenable by genetic and environmental factors. The highly conserved nutrient-responsive Target of Rapamycin (TOR signaling pathway regulates cellular metabolic status and growth in response to numerous inputs. Timing and duration of TOR pathway activity is pivotal for both cell mass built up as well as cell cycle progression and is controlled and fine-tuned by the abundance and quality of nutrients, hormonal signals, growth factors, stress, and oxygen. TOR kinases function within two functionally and structurally discrete multiprotein complexes, TORC1 and TORC2, that are implicated in temporal and spatial control of cell size and growth respectively; however, recent data indicate that such functional distinctions are much more complex. Here, we briefly review roles of the two complexes in cellular growth and cytoarchitecture in various experimental model systems.

  17. A Method of MPPT Control Based on Power Variable Step-size in Photovoltaic Converter System

    Directory of Open Access Journals (Sweden)

    Xu Hui-xiang

    2016-01-01

    Full Text Available Since the disadvantage of traditional MPPT algorithms of variable step-size, proposed power tracking based on variable step-size with the advantage method of the constant-voltage and the perturb-observe (P&O[1-3]. The control strategy modify the problem of voltage fluctuation caused by perturb-observe method, at the same time, introducing the advantage of constant-voltage method and simplify the circuit topology. With the theoretical derivation, control the output power of photovoltaic modules to change the duty cycle of main switch. Achieve the maximum power stabilization output, reduce the volatility of energy loss effectively, and improve the inversion efficiency[3,4]. Given the result of experimental test based theoretical derivation and the curve of MPPT when the prototype work.

  18. Particle size distribution control of Pt particles used for particle gun

    Science.gov (United States)

    Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

    2017-07-01

    The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

  19. The Functionalization, Size Control and Properties of Metal-Organic Frameworks

    DEFF Research Database (Denmark)

    Xu, Hui; Iversen, Bo Brummerstedt

    2016-01-01

    Recent years, Metal-Organic Framework (MOF) materials have drawn great attentions due to their potential applications in gas sorption/separation and luminescent sensing. In this dissertation, the recent progress of MOF materials is reviewed, with specific focus on the functionalization, size...... control and properties of MOF materials. A cationic MOF material was synthesized, and small hydrocarbons C1/C2 sorption/separation properties were studied. A MOF with both open metal sites and Lewis basic pyridyl sites was developed, and C2H2, CO2 and CH4 gas sorption/separation properties were explored....... A nanoscale MOF material with controllable size was realized whose morphology has been simulated base on the BFDH method, and the sensing of bacteria endospores was research in detail. We also report the synthesis and sensing of nitroaromatic explosives of a nanoscale MOF material....

  20. Synthesis and performance of colloidal silica nano-abrasives with controllable size for chemical mechanical planarization.

    Science.gov (United States)

    Zhang, K L; Song, Z T; Wang, F; Wang, L Y; Feng, S L

    2009-02-01

    Under the analysis of particle growth mechanism, the monodisperse colloidal silica abrasives for chemical mechanical planarization (CMP) slurry were synthesized by the modified ion-exchanged and hydrothermal step-polymerization process. After the colloidal silica with controllable size was synthesized, its microstructure, stability and CMP performance was characterized and tested by SEM, HRTEM, Zeta potential Analyzer and CMP tester. Results show that the spherical, high stable (Zeta potential: -52.8 mV) colloidal silica with controllable size was achieved. About its CMP performance, the polishing rate for silicon double-side CMP is increased to be 317 nm/min and the polished surface roughness (RMS) was reduced to 0.32 nm.

  1. Size controllable synthesis of ultrafine spherical gold particles and their simulation of plasmonic and SERS behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Zao [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); College of Physics and Electronics, Central South University, Changsha 410083 (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Xu, Xibin [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); College of Physics and Electronics, Central South University, Changsha 410083 (China); Luo, Jiangshan; Li, Xibo [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Yi, Yong [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang (China); Jiang, Xiaodong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Yi, Yougen, E-mail: yougenyi@mail.csu.edu.cn [College of Physics and Electronics, Central South University, Changsha 410083 (China); Tang, Yongjian [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China); Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China)

    2014-04-01

    A simple and reproducible way was explored to synthesize quasi-spherical gold particles with different size distributions in water by rapidly adding a mixture solution of HAuCl{sub 4}, sodium citrate, and a trace amount of silver nitrate. By careful tuning of the reaction parameters, mono-disperse gold particles with the diameter of 5–220 nm can be obtained controllably. The particle size of 130 nm for the particles film showed the highest SERS activity with the 632.8 nm excitation. The theoretical calculations of the UV–vis extinction spectra can be directly compared with experiments by using the discrete-dipole approximation (DDA). Control of nanostructure shape allows optimization of plasmon resonance for molecular detection and spectroscopy.

  2. A Study of Teacher-Pupil and Pupil-Pupil Interactional Differences Between Inquiry Centered Science and Traditional Science in Elementary Schools.

    Science.gov (United States)

    Rains, Ohren Willis

    Reported is a study of teacher-pupil and pupil-pupil interactional differences between a traditional instruction method and an inquiry-centered learning method for 18 science classes at the fourth and fifth grade levels. Nine classes were assigned to the experimental group, and the remaining nine classes received a traditional program. Classroom…

  3. Size and composition-controlled fabrication of VO2 nanocrystals by terminated cluster growth

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre; Slack, Jonathan

    2013-05-14

    A physical vapor deposition-based route for the fabrication of VO2 nanoparticles is demonstrated, consisting of reactive sputtering and vapor condensation at elevated pressures. The oxidation of vanadium atoms is an efficient heterogeneous nucleation method, leading to high nanoparticle throughtput. Fine control of the nanoparticle size and composition is obtained. Post growth annealing leads to crystalline VO2 nanoparticles with optimum thermocromic and plasmonic properties.

  4. Effect of motor control training on muscle size and football games missed from injury.

    Science.gov (United States)

    Hides, Julie A; Stanton, Warren R; Mendis, M Dilani; Gildea, Jan; Sexton, Margot J

    2012-06-01

    This panel-randomized intervention trial was designed to examine the effect of a motor control training program for elite Australian Football League players with and without low back pain (LBP). The outcome measures included cross-sectional area (CSA) and symmetry of multifidus, quadratus lumborum, and psoas muscles and the change in CSA of the trunk in response to an abdominal drawing-in task. These measures of muscle size and function were performed using magnetic resonance imaging. Availability of players for competition games was used to assess the effect of the intervention on the occurrence of injuries. The motor control program involved performance of voluntary contractions of the multifidus and transversus abdominis muscles while receiving feedback from ultrasound imaging. Because all players were to receive the intervention, the trial was delivered as a stepped-wedge design with three treatment arms (a 15-wk intervention, a 8-wk intervention, and a waitlist control who received a 7-wk intervention toward the end of the playing season). Players participated in a Pilates program when they were not receiving the intervention. The intervention program was associated with an increase in multifidus muscle size relative to results in the control group. The program was also associated with an improved ability to draw-in the abdominal wall. Intervention was commensurate with an increase in availability for games and a high level of perceived benefit. The motor control program delivered to elite footballers was effective, with demonstrated changes in the size and control of the targeted muscles. In this study, footballers who received the intervention early in the season missed fewer games because of injury than those who received it late in the playing season.

  5. Advances in synthesis of calcium phosphate crystals with controlled size and shape.

    Science.gov (United States)

    Lin, Kaili; Wu, Chengtie; Chang, Jiang

    2014-10-01

    Calcium phosphate (CaP) materials have a wide range of applications, including biomaterials, adsorbents, chemical engineering materials, catalysts and catalyst supports and mechanical reinforcements. The size and shape of CaP crystals and aggregates play critical roles in their applications. The main inorganic building blocks of human bones and teeth are nanocrystalline CaPs; recently, much progress has been made in the application of CaP nanocrystals and their composites for clinical repair of damaged bone and tooth. For example, CaPs with special micro- and nanostructures can better imitate the biomimetic features of human bone and tooth, and this offers significantly enhanced biological performances. Therefore, the design of CaP nano-/microcrystals, and the shape and hierarchical structures of CaPs, have great potential to revolutionize the field of hard tissue engineering, starting from bone/tooth repair and augmentation to controlled drug delivery devices. Previously, a number of reviews have reported the synthesis and properties of CaP materials, especially for hydroxyapatite (HAp). However, most of them mainly focused on the characterizations and physicochemical and biological properties of HAp particles. There are few reviews about the control of particle size and size distribution of CaPs, and in particular the control of nano-/microstructures on bulk CaP ceramic surfaces, which is a big challenge technically and may have great potential in tissue engineering applications. This review summarizes the current state of the art for the synthesis of CaP crystals with controlled sizes from the nano- to the macroscale, and the diverse shapes including the zero-dimensional shapes of particles and spheres, the one-dimensional shapes of rods, fibers, wires and whiskers, the two-dimensional shapes of sheets, disks, plates, belts, ribbons and flakes and the three-dimensional (3-D) shapes of porous, hollow, and biomimetic structures similar to biological bone and tooth

  6. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, J. M.; Telling, N. D.; Coker, V. S.; Pattrick, R. A. D.; Laan, G. van der; Arenholz, E.; Tuna, F.; Lloyd, J. R.

    2011-08-02

    The bioproduction of nano-scale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens, by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles has been investigated by X-ray magnetic circular dichroism and indicates the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimised biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently in the less harmful trivalent form.

  7. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens.

    Science.gov (United States)

    Byrne, J M; Telling, N D; Coker, V S; Pattrick, R A D; van der Laan, G; Arenholz, E; Tuna, F; Lloyd, J R

    2011-11-11

    The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.

  8. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens

    Science.gov (United States)

    Byrne, J. M.; Telling, N. D.; Coker, V. S.; Pattrick, R. A. D.; van der Laan, G.; Arenholz, E.; Tuna, F.; Lloyd, J. R.

    2011-11-01

    The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.

  9. Consultation for Small-Sized Penis in the Egyptian Males: A Case Control Study.

    Science.gov (United States)

    Salama, Nader

    2016-05-01

    This study aimed to report penile dimensions in adult Egyptian males consulting for small-sized penis (SSP) and describe their demographics and andrological profile. A case control study was designed through retrospective data analysis of patients (n = 239) seeking advice for SSP and a control group (n = 59). This included sociodemographics, other andrological complaints, and penile dimensions (pendulous length [PL], penopubic or total length [TL], and circumference [CF]) at flaccid and erect states and the size of the prepubic fatty pad. The results reported that most patients were single, students, and smokers and had not completed a university education. Several patients reported falsely premature ejaculation (PE), penile curvature (PC), and small-sized testes. Most penile dimensions of the patients (mean, cm) were significantly lower than those of the controls, whether in flaccid (PL: 7.4 vs. 8.05, p = .008; CF: 8.7 vs. 8.98, p = .026) or erect state (PL: 11.8 vs. 13, p = .000; TL: 14.2 vs. 15, p = .000; CF: 11.3 vs. 11.8, p = .003). However, no patient presented with a pendulous penile length <4 cm in flaccid or <7 cm in erect state. In conclusion, Egyptian men consulting for SSP did not have true small organs, but their penile dimensions were slightly smaller than those of men without such complaint. The proper sexual education program is highly advisable in these situations to avoid the myths and misconceptions about sexuality.

  10. Scalable fabrication of size-controlled chitosan nanoparticles for oral delivery of insulin.

    Science.gov (United States)

    He, Zhiyu; Santos, Jose Luis; Tian, Houkuan; Huang, Huahua; Hu, Yizong; Liu, Lixin; Leong, Kam W; Chen, Yongming; Mao, Hai-Quan

    2017-06-01

    Controlled delivery of protein would find diverse therapeutic applications. Formulation of protein nanoparticles by polyelectrolyte complexation between the protein and a natural polymer such as chitosan (CS) is a popular approach. However, the current method of batch-mode mixing faces significant challenges in scaling up while maintaining size control, high uniformity, and high encapsulation efficiency. Here we report a new method, termed flash nanocomplexation (FNC), to fabricate insulin nanoparticles by infusing aqueous solutions of CS, tripolyphosphate (TPP), and insulin under rapid mixing condition (Re > 1600) in a multi-inlet vortex mixer. In comparison with the bulk-mixing method, the optimized FNC process produces CS/TPP/insulin nanoparticles with a smaller size (down to 45 nm) and narrower size distribution, higher encapsulation efficiency (up to 90%), and pH-dependent nanoparticle dissolution and insulin release. The CS/TPP/insulin nanoparticles can be lyophilized and reconstituted without loss of activity, and produced at a throughput of 5.1 g h(-1) when a flow rate of 50 mL min(-1) is used. Evaluated in a Type I diabetes rat model, the smaller nanoparticles (45 nm and 115 nm) control the blood glucose level through oral administration more effectively than the larger particles (240 nm). This efficient, reproducible and continuous FNC technique is amenable to scale-up in order to address the critical barrier of manufacturing for the translation of protein nanoparticles.

  11. The pupil as an indicator of unconscious memory: Introducing the pupil priming effect.

    Science.gov (United States)

    Gomes, Carlos Alexandre; Montaldi, Daniela; Mayes, Andrew

    2015-06-01

    We explored whether object behavioral priming and pupil changes occur in the absence of recognition memory. Experiment 1 found behavioral priming for unrecognized objects (Ms) regardless of whether they had been encoded perceptually or conceptually. Using the same perceptual encoding task, Experiment 2 showed greater pupil dilation for Ms than for correct rejections of unstudied objects (CRs) when reaction times were matched. In Experiment 3, there was relatively less pupil dilation for Ms than for similarly matched CRs when objects had been encoded conceptually. Mean/peak pupil dilation for CRs, but not Ms, increased in Experiment 3, in which novelty expectation was also reduced, and the pupillary time course for both Ms and CRs was distinct in the two experiments. These findings indicate that both behavioral and pupil memory occur for studied, but unrecognized stimuli, and suggest that encoding and novelty expectation modulate pupillary memory responses.

  12. Myocardial Infarct Size by CMR in Clinical Cardioprotection Studies: Insights From Randomized Controlled Trials.

    Science.gov (United States)

    Bulluck, Heerajnarain; Hammond-Haley, Matthew; Weinmann, Shane; Martinez-Macias, Roberto; Hausenloy, Derek J

    2017-03-01

    The aim of this study was to review randomized controlled trials (RCTs) using cardiac magnetic resonance (CMR) to assess myocardial infarct (MI) size in reperfused patients with ST-segment elevation myocardial infarction (STEMI). There is limited guidance on the use of CMR in clinical cardioprotection RCTs in patients with STEMI treated by primary percutaneous coronary intervention. All RCTs in which CMR was used to quantify MI size in patients with STEMI treated with primary percutaneous coronary intervention were identified and reviewed. Sixty-two RCTs (10,570 patients, January 2006 to November 2016) were included. One-third did not report CMR vendor or scanner strength, the contrast agent and dose used, and the MI size quantification technique. Gadopentetate dimeglumine was most commonly used, followed by gadoterate meglumine and gadobutrol at 0.20 mmol/kg each, with late gadolinium enhancement acquired at 10 min; in most RCTs, MI size was quantified manually, followed by the 5 standard deviation threshold; dropout rates were 9% for acute CMR only and 16% for paired acute and follow-up scans. Weighted mean acute and chronic MI sizes (≤12 h, initial TIMI [Thrombolysis in Myocardial Infarction] flow grade 0 to 3) from the control arms were 21 ± 14% and 15 ± 11% of the left ventricle, respectively, and could be used for future sample-size calculations. Pre-selecting patients most likely to benefit from the cardioprotective therapy (≤6 h, initial TIMI flow grade 0 or 1) reduced sample size by one-third. Other suggested recommendations for standardizing CMR in future RCTs included gadobutrol at 0.15 mmol/kg with late gadolinium enhancement at 15 min, manual or 6-SD threshold for MI quantification, performing acute CMR at 3 to 5 days and follow-up CMR at 6 months, and adequate reporting of the acquisition and analysis of CMR. There is significant heterogeneity in RCT design using CMR in patients with STEMI. The authors provide recommendations for standardizing

  13. Lateral pupil alignment tolerance in peripheral refractometry.

    Science.gov (United States)

    Fedtke, Cathleen; Ehrmann, Klaus; Ho, Arthur; Holden, Brien A

    2011-05-01

    To investigate the tolerance to lateral pupil misalignment in peripheral refraction compared with central refraction. A Shin-Nippon NVision-K5001 open-view auto-refractor was used to measure central and peripheral refraction (30° temporal and 30° nasal visual field) of the right eyes of 10 emmetropic and 10 myopic participants. At each of the three fixation angles, five readings were recorded for each of the following alignment positions relative to pupil center: centrally aligned, 1 and 2 mm temporally aligned, and 1 and 2 mm nasally aligned. For central fixation, increasing dealignment from pupil center produced a quadratic decrease (r ≥ 0.98, p < 0.04) in the refractive power vectors M and J180 which, when interpolated, reached clinical significance (i.e., ≥ 0.25 diopter for M and ≥ 0.125 diopter for J180 and J45) for an alignment error of 0.79 mm or greater. M and J180 as measured in the 30° temporal and 30° nasal visual field led to a significant linear correlation (r ≥ 0.94, p < 0.02) as pupil dealignment gradually changed from temporal to nasal. As determined from regression analysis, a pupil alignment error of 0.20 mm or greater would introduce errors in M and J180 that are clinically significant. Tolerance to lateral pupil alignment error decreases strongly in the periphery compared with the greater tolerance in central refraction. Thus, precise alignment of the entrance pupil with the instrument axis is critical for accurate and reliable peripheral refraction.

  14. Size-controlled silver nanoparticles stabilized on thiol-functionalized MIL-53(Al) frameworks

    Science.gov (United States)

    Cheng, Xinquan; Liu, Min; Zhang, Anfeng; Hu, Shen; Song, Chunshan; Zhang, Guoliang; Guo, Xinwen

    2015-05-01

    A postsynthetic modification method was used to prepare thiol-functionalized metal-organic frameworks (MOFs) by the amidation of mercaptoacetic acid with the amine group, which is present in the frameworks of NH2-MIL-53(Al). By doing this, the thiol group has been successfully grafted on the MOF, which perfectly combined the highly developed pore structures of the MOF with the strong coordination ability of the thiol group. The resulting thiol-functionalized MIL-53(Al) showed a significantly high adsorption capacity for heavy metal ions like Ag+ (182.8 mg g-1). Even more importantly, these grafted thiol groups can be used as anchoring groups for stabilizing metal nanoparticles (NPs) with controllable sizes. Taking silver as an example, monodispersed Ag NPs encapsulated in the cages of MIL-53(Al) have been prepared by using a two-step procedure. In addition, the particle size of the Ag NPs was adjustable to some extent by controlling the initial loading amount. The average size of the smallest Ag NPs is 3.9 +/- 0.9 nm, which is hard to obtain for Ag NPs because of their strong tendency to aggregate.A postsynthetic modification method was used to prepare thiol-functionalized metal-organic frameworks (MOFs) by the amidation of mercaptoacetic acid with the amine group, which is present in the frameworks of NH2-MIL-53(Al). By doing this, the thiol group has been successfully grafted on the MOF, which perfectly combined the highly developed pore structures of the MOF with the strong coordination ability of the thiol group. The resulting thiol-functionalized MIL-53(Al) showed a significantly high adsorption capacity for heavy metal ions like Ag+ (182.8 mg g-1). Even more importantly, these grafted thiol groups can be used as anchoring groups for stabilizing metal nanoparticles (NPs) with controllable sizes. Taking silver as an example, monodispersed Ag NPs encapsulated in the cages of MIL-53(Al) have been prepared by using a two-step procedure. In addition, the particle

  15. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    OpenAIRE

    Veale, D; Miles, S; Read, J.; Troglia, A.; Wylie, K.R.; Muir, G.

    2015-01-01

    Introduction: Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. Aim: To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. Methods: An opportunistic sample of 90 men from the community were recru...

  16. Size Control and Fractionation of Ionic Liquid Filled Polymersomes with Glassy and Rubbery Bilayer Membranes.

    Science.gov (United States)

    So, Soonyong; Lodge, Timothy P

    2016-05-17

    We demonstrate control over the size of ionic liquid (IL) filled polymeric vesicles (polymersomes) by three distinct methods: mechanical extrusion, cosolvent-based processing in an IL, and fractionation of polymersomes in a biphasic system of IL and water. For the representative ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][TFSI])), the size and dispersity of polymersomes formed from 1,2-polybutadiene-b-poly(ethylene oxide) (PB-PEO) and polystyrene-b-poly(ethylene oxide) (PS-PEO) diblock copolymers were shown to be sensitive to assembly conditions. During mechanical extrusion through a polycarbonate membrane, the relatively larger polymersomes were broken up and reorganized into vesicles with mean size comparable to the membrane pore (100 nm radius); the distribution width also decreased significantly after only a few passes. Other routes were studied using the solvent-switch or cosolvent (CS) method, whereby the initial content of the cosolvent and the PEO block length of PS-PEO were systemically changed. The nonvolatility of the ionic liquid directly led to the desired concentration of polymersomes in the ionic liquid using a single step, without the dialysis conventionally used in aqueous systems, and the mean vesicle size depended on the amount of cosolvent employed. Finally, selective phase transfer of PS-PEO polymersomes based on size was used to extract larger polymersomes from the IL to the aqueous phase via interfacial tension controlled phase transfer. The interfacial tension between the PS membrane and the aqueous phase was varied with the concentration of sodium chloride (NaCl) in the aqueous phase; then the larger polymersomes were selectively separated to the aqueous phase due to differences in shielding of the hydrophobic core (PS) coverage by the hydrophilic corona brush (PEO). This novel fractionation is a simple separation process without any special apparatus and can help to prepare monodisperse polymersomes

  17. Temperature and zooplankton size structure: climate control and basin-scale comparison in the North Pacific.

    Science.gov (United States)

    Chiba, Sanae; Batten, Sonia D; Yoshiki, Tomoko; Sasaki, Yuka; Sasaoka, Kosei; Sugisaki, Hiroya; Ichikawa, Tadafumi

    2015-02-01

    The global distribution of zooplankton community structure is known to follow latitudinal temperature gradients: larger species in cooler, higher latitudinal regions. However, interspecific relationships between temperature and size in zooplankton communities have not been fully examined in terms of temporal variation. To re-examine the relationship on a temporal scale and the effects of climate control thereon, we investigated the variation in copepod size structure in the eastern and western subarctic North Pacific in 2000-2011. This report presents the first basin-scale comparison of zooplankton community changes in the North Pacific based on a fully standardized data set obtained from the Continuous Plankton Recorder (CPR) survey. We found an increase in copepod community size (CCS) after 2006-2007 in the both regions because of the increased dominance of large cold-water species. Sea surface temperature varied in an east-west dipole manner, showing the typical Pacific Decadal Oscillation pattern: cooling in the east and warming in the west after 2006-2007. The observed positive correlation between CCS and sea surface temperature in the western North Pacific was inconsistent with the conventional interspecific temperature-size relationship. We explained this discrepancy by the geographical shift of the upper boundary of the thermal niche, the 9°C isotherm, of large cold-water species. In the eastern North Pacific, the boundary stretched northeast, to cover a large part of the sampling area after 2006-2007. In contrast, in the western North Pacific, the isotherm location hardly changed and the sampling area remained within its thermal niche throughout the study period, despite the warming that occurred. Our study suggests that while a climate-induced basin-scale cool-warm cycle can alter copepod community size and might subsequently impact the functions of the marine ecosystem in the North Pacific, the interspecific temperature-size relationship is not

  18. A solid frame for the window on cognition: Modeling event-related pupil responses.

    Science.gov (United States)

    Korn, Christoph W; Bach, Dominik R

    2016-01-01

    Pupil size is often used to infer central processes, including attention, memory, and emotion. Recent research has spotlighted its relation to behavioral variables from decision-making models and to neural variables such as locus coeruleus activity and cortical oscillations. As yet, a unified and principled approach for analyzing pupil responses is lacking. Here we seek to establish a formal, quantitative forward model for pupil responses by describing them with linear time-invariant systems. Based on empirical data from human participants, we show that a combination of two linear time-invariant systems can parsimoniously explain approximately all variance evoked by illuminance changes. Notably, the model makes a counterintuitive prediction that pupil constriction dominates the responses to darkness flashes, as in previous empirical reports. This prediction was quantitatively confirmed for responses to light and darkness flashes in an independent group of participants. Crucially, illuminance- and nonilluminance-related inputs to the pupillary system are presumed to share a common final pathway, composed of muscles and nerve terminals. Hence, we can harness our illuminance-based model to estimate the temporal evolution of this neural input for an auditory-oddball task, an emotional-words task, and a visual-detection task. Onset and peak latencies of the estimated neural inputs furnish plausible hypotheses for the complexity of the underlying neural circuit. To conclude, this mathematical description of pupil responses serves as a prerequisite to refining their relation to behavioral and brain indices of cognitive processes.

  19. Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy.

    Science.gov (United States)

    Karlsson, Johan; Atefyekta, Saba; Andersson, Martin

    2015-01-01

    The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding-diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments.

  20. Grain size control and phase transformations in nanocrystalline ZrO(2)-Al(2)O(3)

    Science.gov (United States)

    Smyser, Bridget Maureen

    1998-12-01

    An effort has been made to develop nanocrystalline ZrOsb2-Alsb2Osb3 powders that exhibit grain size and phase stability during one thermal cycle from room temperature to 1100-1200sp°C for potential use as thermal barrier coating materials. For this use, the tetragonal phase of ZrOsb2 must be maintained. Tetragonal ZrOsb2 can be prevented from transforming to the monoclinic form by maintaining the grain size below a critical value. Alsb2Osb3 was intended to provide this grain size control due to its immiscibility with ZrOsb2. Several sol-gel and precipitation methods of producing the powders were compared, along with two different forms of high energy mixing. The powders were subsequently calcined and heat treated in order to assess their ability to maintain the desired phase distribution during thermal cycling. The powders were characterized by x-ray diffraction and transmission electron microscopy. The method producing the greatest fraction of tetragonal ZrOsb2 with the least amount of added Alsb2Osb3 was that in which a commercial colloidal solution of ZrOsb2 was mixed with an aluminum nitrate solution. The critical grain size of ZrOsb2 in this system was 30 nm. The grain size was controlled not by a pinning mechanism as is often seen in conventional, high Alsb2Osb3,\\ Alsb2Osb3-ZrOsb2 ceramics, but instead by mutual constraint of surrounding grains aided by sluggish grain boundary diffusion. The grain growth kinetics in all the phases tended to be slower than in micron sized materials, and a range of grain growth exponents from n = 1 to n = 30 were determined for the various phases. Transformation kinetics in ZrOsb2 followed classic Avrami behavior. Alsb2Osb3 phase transformation kinetics were not specifically determined, however, gamma-Alsb2Osb3 was identified at temperatures well beyond its usual stability, which is possibly a grain size effect.

  1. Mechanical weed control on small-size dry bean and its response to cross-flaming

    Energy Technology Data Exchange (ETDEWEB)

    Martelloni, L.; Frasconi, C.; Fontanelli, M.; Raffaelli, M.; Peruzzi, A.

    2016-11-01

    Dry bean (Phaseolus vulgaris L.) can be a profitable crop for farmers; however controlling weeds effectively without a decrease in yield remains a problem. An example where mechanical weed control is difficult to conduct is dry bean ‘Toscanello’, which is a small sized high-income niche product growing low to the ground. Concerning intra-row weed control, also flame weeding could be an opportunity but the dry bean heat tolerance needs to be studied. The aims of this research were to study the weed control efficacy of a spring-tine harrow and an inter-row cultivator in this bean variety, and to test the tolerance of dry bean cultivated under weed-free conditions to cross-flaming applied with different liquefied petroleum gas (LPG) doses. Flame weeding was applied at BBCH 13 and BBCH 14 bean growth stages by pairs of burners producing direct double flame acting into the intra-row space, with bean plants placed in the middle. The results suggest that the spring-tine harrow used two times at BBCH 13 and 14, respectively, lead to a yield similar to that of the weedy control. The inter-row cultivator could be an opportunity for small-sized dry bean crops producers, enabling them to obtain a similar yield compared to the hand-weeded control. Concerning the bean tolerance to cross-flaming the results showed that bean flamed at BBCH 13 stage had little tolerance to cross-flaming. Bean flamed at BBCH 14 stage was tolerant until an LPG dose of 39 kg/ha, giving yield responses similar to those observed in the non-flamed control. (Author)

  2. Year 7 Pupils' Views of the Future

    Directory of Open Access Journals (Sweden)

    Ken Roberts

    2011-01-01

    Full Text Available This paper reports findings from a study among 610 Year 7 (typically age 12 pupils at 27 nonselective secondary schools in three English regions: Cornwall and Devon, London, and Greater Manchester. Data was gathered in workshops, each with 15–25 pupils, who completed questionnaires and performed individual tasks, all related to their vocational and educational aims, their ideas on what counted as success, and the main influences on their forward thinking, then discussed their answers and results. The discussions were tape recorded. Most pupils expressed robust occupational aims, and most said that they wanted to go to university. Family class did not predict levels of educational or occupational aims, but was related to the importance attached to “the job that I want to do” in the pupils' forward thinking. SAT scores did predict levels of occupational aspiration, ideas on what counted as success, and by whom and what the pupils were most influenced. These findings are interpreted to challenge the view, on which a raft of current policies are based, that social class disparities in educational and labour market outcomes are due to the intergenerational transmission of low aspirations in lower-class families and neighbourhoods. The paper concludes with an alternative model of status transmission processes in which attainments during secondary education are posited as the key intervening variable.

  3. JWST science instrument pupil alignment measurements

    Science.gov (United States)

    Kubalak, Dave; Sullivan, Joe; Ohl, Ray; Antonille, Scott; Beaton, Alexander; Coulter, Phillip; Hartig, George; Kelly, Doug; Lee, David; Maszkiewicz, Michael; Schweiger, Paul; Telfer, Randal; Te Plate, Maurice; Wells, Martyn

    2016-09-01

    NASA's James Webb Space Telescope (JWST) is a 6.5m diameter, segmented, deployable telescope for cryogenic IR space astronomy ( 40K). The JWST Observatory architecture includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) element that contains four science instruments (SI), including a guider. OSIM is a full field, cryogenic, optical simulator of the JWST OTE. It is the "Master Tool" for verifying the cryogenic alignment and optical performance of ISIM by providing simulated point source/star images to each of the four Science Instruments in ISIM. Included in OSIM is a Pupil Imaging Module (PIM) - a large format CCD used for measuring pupil alignment. Located at a virtual stop location within OSIM, the PIM records superimposed shadow images of pupil alignment reference (PAR) targets located in the OSIM and SI pupils. The OSIM Pupil Imaging Module was described by Brent Bos, et al, at SPIE in 2011 prior to ISIM testing. We have recently completed the third and final ISIM cryogenic performance verification test before ISIM was integrated with the OTE. In this paper, we describe PIM implementation, performance, and measurement results.

  4. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae, E-mail: nicolae.leopold@phys.ubbcluj.ro [Babeş-Bolyai University, Faculty of Physics (Romania)

    2014-12-15

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl{sub 4} by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of ∼20 and ∼120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4–8 and 10–30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV–Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  5. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Science.gov (United States)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae

    2014-12-01

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl4 by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of 20 and 120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4-8 and 10-30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV-Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  6. Size-Controlled and Optical Properties of Monodispersed Silver Nanoparticles Synthesized by the Radiolytic Reduction Method

    Directory of Open Access Journals (Sweden)

    Kazem Naghavi

    2013-04-01

    Full Text Available Size-controlled and monodispersed silver nanoparticles were synthesized from an aqueous solution containing silver nitrate as a metal precursor, polyvinyl alcohol as a capping agent, isopropyl alcohol as hydrogen and hydroxyl radical scavengers, and deionized water as a solvent with a simple radiolytic method. The average particle size decreased with an increase in dose due to the domination of nucleation over ion association in the formation of the nanoparticles by gamma reduction. The silver nanoparticles exhibit a very sharp and strong absorption spectrum with the absorption maximum λmax blue shifting with an increased dose, owing to a decrease in particle size. The absorption spectra of silver nanoparticles of various particle sizes were also calculated using a quantum physics treatment and an agreement was obtained with the experimental absorption data. The results suggest that the absorption spectrum of silver nanoparticles possibly derived from the intra-band excitations of conduction electrons from the lowest energy state (n = 5, l = 0 to higher energy states (n ≥ 6; Δl = 0, ±1; Δs = 0, ±1, allowed by the quantum numbers principle. This demonstrates that the absorption phenomenon of metal nanoparticles based on a quantum physics description could be exploited to be added into the fundamentals of metal nanoparticles and the related fields of nanoscience and nanotechnology.

  7. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    Directory of Open Access Journals (Sweden)

    David Veale, MD, FRCPsych

    2015-09-01

    Conclusion: Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures. Veale D, Miles S, Read J, Troglia A, Wylie K, and Muir G. Sexual functioning and behavior of men with body dysmorphic disorder concerning penis size compared with men anxious about penis size and with controls: A cohort study. Sex Med 2015;3:147–155.

  8. Optimization of size controlled poly (lactide-co-glycolic acid nanoparticles using quality by design concept

    Directory of Open Access Journals (Sweden)

    Padmanabha R. V. Reddy

    2015-01-01

    Full Text Available Quality by design (QbD is a risk management and science-based approach laid down by the ICH as well as other Regulatory agencies to enhance pharmaceutical development throughout a product′s lifecycle. Poly(lactide-co-glycolic acid (PLGA is the material of choice for development of depot particulate formulations due to its biodegradable nature and is also considered as the ′green′ eco-friendly material due its biocompatibility and non-toxic properties. Further, PLGA based formulations are approved by regulatory agencies and currently in clinical practice. The aim of the current investigation involves formulation, optimization and in vitro characterization of size controlled PLGA based nanoparticles by employing modified nanoprecipitation technique. An initial risk-assessment analysis was conducted with different formulation and process variables along with their impact on critical quality attributes of the formulation which were identified as particle size and percentage process yield. The Ishikawa diagram was employed to determine the potential risk factors and subsequently optimized by statistical experimental design concept. Box-Behnken design was utilized to optimize nanoparticles and further characterizing the optimized nanoparticulate formulation in vitro. From the present study, it can be concluded that PLGA based nanoparticles with controlled particle size and process yield can be obtained by inculcating the concept of QbD in the product development.

  9. Controllable synthesis of gold nanoparticles with ultrasmall size and high monodispersity via continuous supplement of precursor.

    Science.gov (United States)

    Li, Yuanyuan; Liu, Shoujie; Yao, Tao; Sun, Zhihu; Jiang, Zheng; Huang, Yuying; Cheng, Hao; Huang, Yuanyuan; Jiang, Yong; Xie, Zhi; Pan, Guoqiang; Yan, Wensheng; Wei, Shiqiang

    2012-10-14

    Synthesis of monodisperse small Au nanoparticles in a controllable manner is of great importance for fundamental science and technical applications. Here, we report a "precursor continuous-supply" strategy for controllable synthesis of 0.9-3.3 nm Au nanoparticles with a narrow size distribution of 0.1-0.2 nm, using a weak reductant to slow-down the reducing rate of AuClPPh(3) precursor in ethanol. Time-dependent X-ray absorption and UV-Vis absorption measurements revealed that owing to the joint use of AuClPPh(3) and ethanol, the remnant AuClPPh(3) was self-supplied and the precursor concentration was maintained at a level near to its equilibrium solubility (ca. 1.65 mmol L(-1)) in ethanol. Hence the nucleation duration was extended that focused the initial size distribution of the Au clusters. With reaction going on for 58 min, most of AuClPPh(3) with a nominal Au concentration of 17.86 mmol L(-1) was converted to ethanol-soluble Au clusters with a size of about 1.0 nm, resulting in a high-yield synthesis.

  10. Controlling micro-sized droplet generation using electrical pulses for studying liquid-liquid systems

    Science.gov (United States)

    Fernandino, M.; La Forgia, N.; Vera, A. J.; Bjerknes, J.; Dorao, C. A.

    2014-04-01

    Water droplets removal from oil is a critical process in several industries, in particular in the oil and gas industry. Water/oil separation is commonly done in large gravitational sedimentation tanks, which are over dimensioned due to the lack of accurate models to allow for optimization. This can become challenging for off-shore and subsea processing installations. One of the bottlenecks to study droplet dynamics in the micron range, is the generation of droplets with less than 100μm in diameter. In this regard, one of the most promising techniques for controlling the generated droplet size is based on the use of a high voltage electrical signal or electro-hydrodynamic technique (EHD). Although much work on EHD and droplet generation can been found in the literature, many challenges still remain. One of this is the generation of droplets smaller than 100μm in diameter in a controllable, on-demand manner. In this work, the effect of the meniscus shape and the electric pulse characteristics on the size of the generated droplet is investigated. Both the meniscus height and width help to determine the droplet size, with the latter having a stronger effect. No significant influence of the pulse amplitude and pulse width was observed for the tested conditions.

  11. Self-assembly of size-controlled liposomes on DNA nanotemplates

    Science.gov (United States)

    Yang, Yang; Wang, Jing; Shigematsu, Hideki; Xu, Weiming; Shih, William M.; Rothman, James E.; Lin, Chenxiang

    2016-05-01

    Artificial lipid-bilayer membranes are valuable tools for the study of membrane structure and dynamics. For applications such as the study of vesicular transport and drug delivery, there is a pressing need for artificial vesicles with controlled size. However, controlling vesicle size and shape with nanometre precision is challenging, and approaches to achieve this can be heavily affected by lipid composition. Here, we present a bio-inspired templating method to generate highly monodispersed sub-100-nm unilamellar vesicles, where liposome self-assembly was nucleated and confined inside rigid DNA nanotemplates. Using this method, we produce homogeneous liposomes with four distinct predefined sizes. We also show that the method can be used with a variety of lipid compositions and probe the mechanism of templated liposome formation by capturing key intermediates during membrane self-assembly. The DNA nanotemplating strategy represents a conceptually novel way to guide lipid bilayer formation and could be generalized to engineer complex membrane/protein structures with nanoscale precision.

  12. Integration of epigenetic and genetic controls of seed size by cytokinin in Arabidopsis.

    Science.gov (United States)

    Li, Jing; Nie, Xin; Tan, Jeanie Li Hui; Berger, Frédéric

    2013-09-17

    The development of seeds in flowering plants is placed under complex interactions between maternal tissues, the embryo, and the endosperm. The endosperm plays a major role in the regulation of seed size. In Arabidopsis thaliana, endosperm size depends on the coordination of the genetic pathway HAIKU (IKU) with epigenetic controls comprising genome dosage, DNA methylation, and trimethylated lysine 27 on histone H3 (H3K27me3) deposition. However, the effectors that integrate these pathways have remained unknown. Here, we identify a target of the IKU pathway, the cytokinin oxidase CKX2, that affects cytokinin signaling. CKX2 expression is activated by the IKU transcription factor WRKY10 directly and promotes endosperm growth. CKX2 expression also depends on H3K27me3 deposition, which fluctuates in response to maternal genome dosage imbalance and DNA demethylation of male gametes. Hence, the control of endosperm growth by CKX2 integrates genetic and epigenetic regulations. In angiosperms, cytokinins are highly active in endosperm, and we propose that IKU effectors coordinate environmental and physiological factors, resulting in modulation of seed size.

  13. Quantifying the size-resolved dynamics of indoor bioaerosol transport and control.

    Science.gov (United States)

    Kunkel, S A; Azimi, P; Zhao, H; Stark, B C; Stephens, B

    2017-09-01

    Understanding the bioaerosol dynamics of droplets and droplet nuclei emitted during respiratory activities is important for understanding how infectious diseases are transmitted and potentially controlled. To this end, we conducted experiments to quantify the size-resolved dynamics of indoor bioaerosol transport and control in an unoccupied apartment unit operating under four different HVAC particle filtration conditions. Two model organisms (Escherichia coli K12 and bacteriophage T4) were aerosolized under alternating low and high flow rates to roughly represent constant breathing and periodic coughing. Size-resolved aerosol sampling and settle plate swabbing were conducted in multiple locations. Samples were analyzed by DNA extraction and quantitative polymerase chain reaction (qPCR). DNA from both organisms was detected during all test conditions in all air samples up to 7 m away from the source, but decreased in magnitude with the distance from the source. A greater fraction of T4 DNA was recovered from the aerosol size fractions smaller than 1 μm than E. coli K12 at all air sampling locations. Higher efficiency HVAC filtration also reduced the amount of DNA recovered in air samples and on settle plates located 3-7 m from the source. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Control of pore size and structure of tissue engineering scaffolds produced by supercritical fluid processing

    Directory of Open Access Journals (Sweden)

    H Tai

    2007-12-01

    Full Text Available Tissue engineering scaffolds require a controlled pore size and structure to host tissue formation. Supercritical carbon dioxide (scCO2 processing may be used to form foamed scaffolds in which the escape of CO2 from a plasticized polymer melt generates gas bubbles that shape the developing pores. The process of forming these scaffolds involves a simultaneous change in phase in the CO2 and the polymer, resulting in rapid expansion of a surface area and changes in polymer rheological properties. Hence, the process is difficult to control with respect to the desired final pore size and structure. In this paper, we describe a detailed study of the effect of polymer chemical composition, molecular weight and processing parameters on final scaffold characteristics. The study focuses on poly(DL-lactic acid (PDLLA and poly(DL-lactic acid-co-glycolic acid (PLGA as polymer classes with potential application as controlled release scaffolds for growth factor delivery. Processing parameters under investigation were temperature (from 5 to 55oC and pressure (from 60 to 230 bar. A series of amorphous PDLLA and PLGA polymers with various molecular weights (from 13 KD to 96 KD and/or chemical compositions (the mole percentage of glycolic acid in the polymers was 0, 15, 25, 35 and 50 respectively were employed. The resulting scaffolds were characterised by optical microscopy, scanning electron microscopy (SEM, and micro X-ray computed tomography (µCT. This is the first detailed study on using these series polymers for scaffold formation by supercritical technique. This study has demonstrated that the pore size and structure of the supercritical PDLLA and PLGA scaffolds can be tailored by careful control of processing conditions.

  15. Active impulsive noise control using maximum correntropy with adaptive kernel size

    Science.gov (United States)

    Lu, Lu; Zhao, Haiquan

    2017-03-01

    The active noise control (ANC) based on the principle of superposition is an attractive method to attenuate the noise signals. However, the impulsive noise in the ANC systems will degrade the performance of the controller. In this paper, a filtered-x recursive maximum correntropy (FxRMC) algorithm is proposed based on the maximum correntropy criterion (MCC) to reduce the effect of outliers. The proposed FxRMC algorithm does not requires any priori information of the noise characteristics and outperforms the filtered-x least mean square (FxLMS) algorithm for impulsive noise. Meanwhile, in order to adjust the kernel size of FxRMC algorithm online, a recursive approach is proposed through taking into account the past estimates of error signals over a sliding window. Simulation and experimental results in the context of active impulsive noise control demonstrate that the proposed algorithms achieve much better performance than the existing algorithms in various noise environments.

  16. Synthesis of supported bimetallic nanoparticles with controlled size and composition distributions for active site elucidation

    Energy Technology Data Exchange (ETDEWEB)

    Hakim, Sikander H.; Sener, Canan; Alba Rubio, Ana C.; Gostanian, Thomas M.; O' neill, Brandon J; Ribeiro, Fabio H.; Miller, Jeffrey T.; Dumesic, James A

    2015-08-01

    Elucidation of active sites in supported bimetallic catalysts is complicated by the high level of dispersity in the nanoparticle size and composition that is inherent in conventional methods of catalyst preparation. We present a synthesis strategy that leads to highly dispersed, bimetallic nanoparticles with uniform particle size and composition by means of controlled surface reactions. We demonstrate the synthesis of three systems, RhMo, PtMo, and RhRe, consisting of a highly reducible metal with an oxophilic promoter. These catalysts are characterized by FTIR, CO chemisorption, STEM/EDS, TPR, and XAS analysis. The catalytic properties of these bimetallic nanoparticles were probed for the selective CO hydrogenolysis of (hydroxymethyl)tetrahydropyran to produce 1,6 hexanediol. Based on the characterization results and reactivity trends, the active sites in the hydrogenolysis reaction are identified to be small ensembles of the more noble metal (Rh, Pt) adjacent to highly reduced moieties of the more oxophilic metal (Mo, Re).

  17. One-pot size and shape controlled synthesis of DMSO capped iron oxide nanoparticles

    Indian Academy of Sciences (India)

    Debanjan Guin; Sunkara V Manorama; S Radha; A K Nigam

    2006-11-01

    We report here the capping of iron oxide nanoparticles with dimethyl sulfoxide (DMSO) to make chloroform soluble iron oxide nanoparticles. Size and shape of the capped iron oxide nanoparticles are well controlled by simply varying the reaction parameters. The synthesized nanocrystallites were characterized by thermal analysis (TG–DTA), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) for evaluating phase, structure and morphology. 1H NMR spectra of the synthesized samples confirm DMSO, and the capping of DMSO on the ferrite samples. Shift of the S=O stretching frequency in Fourier transformed infrared (FTIR) spectra indicates that the bonding between DMSO and ferrite is through an oxygen moiety. The magnetic measurements of all the synthesized samples were investigated with a SQUID magnetometer which shows that the magnetic properties are strongly dependent on the size as well as shape of the iron oxide.

  18. A LCMT1-PME-1 methylation equilibrium controls mitotic spindle size.

    Science.gov (United States)

    Xia, Xiaoyu; Gholkar, Ankur; Senese, Silvia; Torres, Jorge Z

    2015-01-01

    Leucine carboxyl methyltransferase-1 (LCMT1) and protein phosphatase methylesterase-1 (PME-1) are essential enzymes that regulate the methylation of the protein phosphatase 2A catalytic subunit (PP2AC). LCMT1 and PME-1 have been linked to the regulation of cell growth and proliferation, but the underlying mechanisms have remained elusive. We show here an important role for an LCMT1-PME-1 methylation equilibrium in controlling mitotic spindle size. Depletion of LCMT1 or overexpression of PME-1 led to long spindles. In contrast, depletion of PME-1, pharmacological inhibition of PME-1 or overexpression of LCMT1 led to short spindles. Furthermore, perturbation of the LCMT1-PME-1 methylation equilibrium led to mitotic arrest, spindle assembly checkpoint activation, defective cell divisions, induction of apoptosis and reduced cell viability. Thus, we propose that the LCMT1-PME-1 methylation equilibrium is critical for regulating mitotic spindle size and thereby proper cell division.

  19. Strategies to control the particle size distribution of poly-epsilon-caprolactone nanoparticles for pharmaceutical applications.

    Science.gov (United States)

    Lince, Federica; Marchisio, Daniele L; Barresi, Antonello A

    2008-06-15

    In this work turbulent precipitation through solvent displacement for the production of poly-epsilon-caprolactone (PCL) nanoparticles is investigated; two different PCL molecular weights have been employed, using acetone and water as solvent and anti-solvent, respectively. The main important thermodynamic and kinetic parameters, such as solubility and interfacial tension of PCL in water-acetone mixtures, are determined and the effect of the process operating conditions on the final particle size distribution is also investigated. Particles produced under different conditions into a Confined Impinging Jets Reactor (CIJR) were characterized by Dynamic Light Scattering, Zeta potential measurements and Scanning Electronic Microscopy. Results clearly show the strong effect of mixing on the particle size distribution and how mixing must be controlled in order to obtain a product with particular characteristics. Eventually the measured thermodynamic and kinetic parameters are used to interpret the obtained experimental data.

  20. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    Science.gov (United States)

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  1. Metal–Organic Frameworks (MOFs) as Multivalent Materials: Size Control and Surface Functionalization by Monovalent Capping Ligands

    NARCIS (Netherlands)

    Rijnaarts, Timon; Weinhart-Mejia, R.; Egberink, Richard J.M.; van Roosmalen, W.P.E.; Huskens, Jurriaan

    2015-01-01

    Control over particle size and composition are pivotal to tune the properties of metal organic frameworks (MOFs), for example, for biomedical applications. Particle-size control and functionalization of MIL-88A were achieved by using stoichiometric replacement of a small fraction of the divalent

  2. Suzuki Meets Polya: Teaching Mathematics to Young Pupils.

    Science.gov (United States)

    Hazlewood, Donald G.; And Others

    1989-01-01

    Describes how Suzuki's methods of teaching young pupils to play the violin can be combined with Polya's ideas on problem solving to teach mathematics to elementary school pupils. Six references are listed. (YP)

  3. A microchip to analyze single crystal growth and size-controllability

    Institute of Scientific and Technical Information of China (English)

    PANG YuanFeng; LIU JiangJiang; LI HaiFang; LIN JinMing

    2009-01-01

    A microfluidic device to control single crystallization on the micron scale has been developed.The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip.The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming.This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot.Therefore,it is possible to control the position of crystallization on the fixed plot.We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors,such as interface lifetime,breeds of the mix-organic solvents and inject- ing velocities.The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals,which nearly shows the same trend compared with the macroscopic crystallization.Finally,the effect of the surfactant on the crystallization in the micro-device was studied.By adding the surfactant into the liquid-liquid interface,smaller sizes of crystals can be obtained without changing the crystal configuration.

  4. Size controlled synthesis of biocompatible gold nanoparticles and their activity in the oxidation of NADH.

    Science.gov (United States)

    Chandran, Parvathy R; Naseer, M; Udupa, N; Sandhyarani, N

    2012-01-13

    Size and shape controlled synthesis remains a major bottleneck in the research on nanoparticles even after the development of different methods for their preparation. By tuning the size and shape of a nanoparticle, the intrinsic properties of the nanoparticle can be controlled leading tremendous potential applications in different fields of science and technology. We describe a facile route for the one pot synthesis of gold nanoparticles in water using monosodium glutamate as the reducing and stabilizing agent in the absence of seed particles. The particle diameter can be easily controlled by varying the pH of the reaction medium. Nanoparticles were characterized using scanning electron microscopy, UV-vis absorption spectroscopy, cyclic voltammetry, and dynamic light scattering. Zeta potential measurements were made to compare the stability of the different nanoparticles. The results suggest that lower pH favours a nucleation rate giving rise to smaller particles and higher pH favours a growth rate leading to the formation of larger particles. The synthesized nanoparticles are found to be stable and biocompatible. The nanoparticles synthesized at high pH exhibited a good electrocatalytic activity towards oxidation of nicotinamide adenine dinucleotide (NADH).

  5. A microchip to analyze single crystal growth and size-controllability

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A microfluidic device to control single crystallization on the micron scale has been developed. The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip. The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming. This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot. Therefore, it is possible to control the position of crystallization on the fixed plot. We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors, such as interface lifetime, breeds of the mix-organic solvents and injecting velocities. The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals, which nearly shows the same trend compared with the macroscopic crystallization. Finally, the effect of the surfactant on the crystallization in the microdevice was studied. By adding the surfactant into the liquid-liquid interface, smaller sizes of crystals can be obtained without changing the crystal configuration.

  6. Adaptive optics scanning ophthalmoscopy with annular pupils.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2012-07-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

  7. Academic outcomes in school classes with markedly disruptive pupils

    OpenAIRE

    Bru, Edvin

    2009-01-01

    The aim of the present research is to investigate the degree to which average academic outcomes in secondary school classes are associated with the inclusion of markedly disruptive pupils. Findings are based on two separate studies among pupils in Norwegian secondary schools. The first s tudy i ncluded a r elatively large sample of 2,332 pupils from 105 school classes and used pupil report of disruptive behaviour, perceived peace to learn and grades achieved. A second study, co...

  8. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.

    2009-12-09

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  9. Comparative analysis of non-destructive methods to control fissile materials in large-size containers

    Directory of Open Access Journals (Sweden)

    Batyaev V.F.

    2017-01-01

    Full Text Available The analysis of various non-destructive methods to control fissile materials (FM in large-size containers filled with radioactive waste (RAW has been carried out. The difficulty of applying passive gamma-neutron monitoring FM in large containers filled with concreted RAW is shown. Selection of an active non-destructive assay technique depends on the container contents; and in case of a concrete or iron matrix with very low activity and low activity RAW the neutron radiation method appears to be more preferable as compared with the photonuclear one.

  10. Pupil modeling of the legibility of class teachers’ board writing

    Directory of Open Access Journals (Sweden)

    Seyit Ateş

    2009-07-01

    Full Text Available The main aim of this study was to examine the pupil modeling of the legibility of class teachers’ writing on the classroom board. A stylistic quality of writing, legibility is evaluated by criteria such as letter slope, spacing, size, shape and line straightness. The study group included 70 class teachers from 13 primary schools at the city center of Kırşehir. The study was a descriptive situation analysis and data were gathered by the document analysis method. Writing samples were gathered by photographing classroom boards, and then analyzed and evaluated by using legibility criteria. The results showed that while the majority of teachers used cursive and many used manuscript, some teachers used the two types of writing together. Among those who wrote cursive handwriting, almost half had inadequate slope but moderately adequate spacing, size, shape and line straightness. It was also found that writing on a blackboard produced better legible writing than that on a white board.

  11. Pupils' Perspectives on the Lived Pedagogy of the Classroom

    Science.gov (United States)

    Niemi, Reetta; Kumpulainen, Kristiina; Lipponen, Lasse; Hilppö, Jaakko

    2015-01-01

    This paper is based on a pedagogical action research initiative that explores what constitutes the "lived pedagogy" of the classroom from the pupils' perspective. Photography and group interviews were utilised to allow pupils to express their perspectives. The results show that pupils considered situations meaningful when they were able…

  12. Pupils' Humour Directed at Teachers: Its Types and Functions

    Science.gov (United States)

    Šedová, Klára

    2013-01-01

    Based on an analysis of 137 texts written by pupils, this paper examines pupils' humour directed at teachers, its types and social functions. The collected data are divided into three categories that describe different modes of teachers as targets of pupils' humour. The first mode describes teachers as unintentionally comical, the second as duped…

  13. Pupils' Attitudes toward Chemistry in Two Types of Czech Schools

    Science.gov (United States)

    Kubiatko, Milan; Balatova, Kristyna; Fancovicova, Jana; Prokop, Pavol

    2017-01-01

    Chemistry is a school subject that is not viewed favorably among pupils. Before we can improve pupils' attitudes toward chemistry, it is important to find out the problem as to why the attitudes are relatively negative. The research was focused on Czech lower secondary and secondary grammar school pupils' attitudes to the subject of chemistry.…

  14. Assisting Pupils in Mathematics Achievement (The Common Core Standards)

    Science.gov (United States)

    Ediger, Marlow

    2011-01-01

    Mathematics teachers must expect reasonably high standards of achievement from pupils. Too frequently, pupils attain at a substandard level and more optimal achievement is necessary. Thus, pupils should have self esteem needs met in the school and classroom setting. Thus, learners feel that mathematics is worthwhile and effort must be put forth to…

  15. Social context effects on pupils' perception of school

    NARCIS (Netherlands)

    Hofman, R.H.; Hofman, W.H.A.; Guldemond, H

    In this study we test the effects of three social contexts of learning on the affective outcomes of schooling, in this case pupils' perception of their primary school. The concept of pupils' school perception is measured using a reliable scale. This scale contains items to measure pupils' perception

  16. Pupil Welfare in Finnish Schools -- Communal or Falling Apart?

    Science.gov (United States)

    Koskela, Teija; Määttä, Kaarina; Uusiautti, Satu

    2013-01-01

    The need for pupil welfare has increased in schools as has the need to renew the traditional teacher's work. The purpose of this article is to find out how committed the teachers are to pupil welfare work and how the school organisation supports pupil welfare work structurally and practically. The original research was carried out in northern…

  17. Cyberbullying: Its Nature and Impact in Secondary School Pupils

    Science.gov (United States)

    Smith, Peter K.; Mahdavi, Jess; Carvalho, Manuel; Fisher, Sonja; Russell, Shanette; Tippett, Neil

    2008-01-01

    Background: Cyberbullying describes bullying using mobile phones and the internet. Most previous studies have focused on the prevalence of text message and email bullying. Methods: Two surveys with pupils aged 11-16 years: (1) 92 pupils from 14 schools, supplemented by focus groups; (2) 533 pupils from 5 schools, to assess the generalisability of…

  18. Cyberbullying: Its Nature and Impact in Secondary School Pupils

    Science.gov (United States)

    Smith, Peter K.; Mahdavi, Jess; Carvalho, Manuel; Fisher, Sonja; Russell, Shanette; Tippett, Neil

    2008-01-01

    Background: Cyberbullying describes bullying using mobile phones and the internet. Most previous studies have focused on the prevalence of text message and email bullying. Methods: Two surveys with pupils aged 11-16 years: (1) 92 pupils from 14 schools, supplemented by focus groups; (2) 533 pupils from 5 schools, to assess the generalisability of…

  19. On Pupils' Self-Confidence in Mathematics: Gender Comparisons

    Science.gov (United States)

    Nurmi, Anu; Hannula, Markku; Maijala, Hanna; Pehkonen, Erkki

    2003-01-01

    In this paper we will concentrate on pupils' self-confidence in mathematics, which belongs to pupils' mathematical beliefs in themselves, and beliefs on achievement in mathematics. Research described consists of a survey of more than 3000 fifth-graders and seventh-graders. Furthermore, 40 pupils participated in a qualitative follow-up study…

  20. Nonaqueous magnetic nanoparticle suspensions with controlled particle size and nuclear magnetic resonance properties.

    Science.gov (United States)

    Meledandri, Carla J; Stolarczyk, Jacek K; Ghosh, Swapankumar; Brougham, Dermot F

    2008-12-16

    We report the preparation of monodisperse maghemite (gamma-Fe2O3) nanoparticle suspensions in heptane, by thermal decomposition of iron(III) acetylacetonate in the presence of oleic acid and oleylamine surfactants. By varying the surfactant/Fe precursor mole ratio during synthesis, control was exerted both over the nanocrystal core size, in the range from 3 to 6 nm, and over the magnetic properties of the resulting nanoparticle dispersions. We report field-cycling 1H NMR relaxation analysis of the superparamagnetic relaxation rate enhancement of nonaqueous suspensions for the first time. This approach permits measurement of the relaxivity and provides information on the saturation magnetization and magnetic anisotropy energy of the suspended particles. The saturation magnetization was found to be in the expected range for maghemite particles of this size. The anisotropy energy was found to increase significantly with decreasing particle size, which we attribute to increased shape anisotropy. This study can be used as a guide for the synthesis of maghemite nanoparticles with selected magnetic properties for a given application.

  1. A web application for sample size and power calculation in case-control microbiome studies.

    Science.gov (United States)

    Mattiello, Federico; Verbist, Bie; Faust, Karoline; Raes, Jeroen; Shannon, William D; Bijnens, Luc; Thas, Olivier

    2016-07-01

    : When designing a case-control study to investigate differences in microbial composition, it is fundamental to assess the sample sizes needed to detect an hypothesized difference with sufficient statistical power. Our application includes power calculation for (i) a recoded version of the two-sample generalized Wald test of the 'HMP' R-package for comparing community composition, and (ii) the Wilcoxon-Mann-Whitney test for comparing operational taxonomic unit-specific abundances between two samples (optional). The simulation-based power calculations make use of the Dirichlet-Multinomial model to describe and generate abundances. The web interface allows for easy specification of sample and effect sizes. As an illustration of our application, we compared the statistical power of the two tests, with and without stratification of samples. We observed that statistical power increases considerably when stratification is employed, meaning that less samples are needed to detect the same effect size with the same power. The web interface is written in R code using Shiny (RStudio Inc., 2016) and it is available at https://fedematt.shinyapps.io/shinyMB The R code for the recoded generalized Wald test can be found at https://github.com/mafed/msWaldHMP CONTACT: Federico.Mattiello@UGent.be. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  2. Shape-controlled synthesis of highly monodisperse and small size gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We describe here that fine control of nanoparticle shape and size can be achieved by systematic varia-tion of experimental parameters in the seeded growth procedure in aqueous solution. Cubic and spherical gold nanoparticles are obtained respectively. In particularly, the Au cubes are highly mono-disperse in 33±2 nm diameter. The experimental methods involve the preparation of Au seed particles and the subsequent addition of an appropriate quantity of Au seed solution to the aqueous growth solutions containing desired quantities of CTAB and ascorbic acid (AA). Here, AA is a weak reducing agent and CTAB is not only a stable agent for nanoparticles but also an inductive agent for leading increase in the face of nanoparticle. Ultraviolet visible spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) are used to characterize the nanoparticles. The results show that the different size gold nanoparticles displayed high size homogenous distribution and formed mono-membrane at the air/solid interface.

  3. Segmented Polyurethane Nanocomposites: Impact of Controlled Particle Size Nanofillers on the Morphological Response to Uniaxial Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Finnigan, Bradley; Jack, Kevin; Campbell, Kayleen; Halley, Peter; Truss, Rowan; Casey, Phil; Cookson, David; King, Stephen; Martin, Darren (Rutherford); (ASRP); (Queensland); (CSIRO)

    2008-10-03

    A series of TPU nanocomposites were prepared by incorporating organically modified layered silicates with controlled particle size. To our knowledge, this is the first study into the effects of layered silicate diameter in polymer nanocomposites utilizing the same mineral for each size fraction. The tensile properties of these materials were found to be highly dependent upon the size of the layered silicates. A decrease in disk diameter was associated with a sharp upturn in the stress-strain curve and a pronounced increase in tensile strength. Results from SAXS/SANS experiments showed that the layered silicates did not affect the bulk TPU microphase structure and the morphological response of the host TPU to deformation or promote/hinder strain-induced soft segment crystallization. The improved tensile properties of the nanocomposites containing the smaller nanofillers resulted from the layered silicates aligning in the direction of strain and interacting with the TPU sequences via secondary bonding. This phenomenon contributes predominantly above 400% strain once the microdomain architecture has largely been disassembled. Large tactoids that are unable to align in the strain direction lead to concentrated tensile stresses between the polymer and filler, instead of desirable shear stresses, resulting in void formation and reduced tensile properties. In severe cases, such as that observed for the composite containing the largest silicate, these voids manifest visually as stress whitening.

  4. Particle size control of LiCoO{sub 2} powders by powder engineering methods

    Energy Technology Data Exchange (ETDEWEB)

    Shlyakhtin, O.A. [Korea Inst. of Science and Technology, Seoul (Korea). Materials Science and Technology Division; Moscow State Univ. (Russian Federation). Dept. of Chemistry; Young Soo Yoon; Young Jei Oh [Korea Inst. of Science and Technology, Seoul (Korea). Materials Science and Technology Division

    2003-10-01

    The directed influence on the micromorphology of precursors during preparation of lithium cobaltate powders by chemical synthesis methods allows to control the size of LiCoO{sub 2} crystallites from 4-6 {mu}m to 60-100 nm. Localization of melting during thermolysis by mixing acetate precursors with foaming agents promotes the reduction of grain size from 4-6 down to 1-1.5 {mu}m. More efficient prevention of grain coalescence can be performed by introducing a thermally stable inert encapsulation agent (K{sub 2}SO{sub 4}) removed by dissolution after thermal processing. The combination of this method with intense deagglomeration of precursor mixtures by planetary milling results in keeping the grain size at the level of primary LiCoO{sub 2} particles (60-80 nm) even at T=800 {sup o}C. Intense mechanical processing of as-formed LiCoO{sub 2} powders is undesirable due to negative influence on the crystallographic ordering processes. (author)

  5. TELICS—A Telescope Instrument Control System for Small/Medium Sized Astronomical Observatories

    Science.gov (United States)

    Srivastava, Mudit K.; Ramaprakash, A. N.; Burse, Mahesh P.; Chordia, Pravin A.; Chillal, Kalpesh S.; Mestry, Vilas B.; Das, Hillol K.; Kohok, Abhay A.

    2009-10-01

    For any modern astronomical observatory, it is essential to have an efficient interface between the telescope and its back-end instruments. However, for small and medium-sized observatories, this requirement is often limited by tight financial constraints. Therefore a simple yet versatile and low-cost control system is required for such observatories to minimize cost and effort. Here we report the development of a modern, multipurpose instrument control system TELICS (Telescope Instrument Control System) to integrate the controls of various instruments and devices mounted on the telescope. TELICS consists of an embedded hardware unit known as a common control unit (CCU) in combination with Linux-based data acquisition and user interface. The hardware of the CCU is built around the ATmega 128 microcontroller (Atmel Corp.) and is designed with a backplane, master-slave architecture. A Qt-based graphical user interface (GUI) has been developed and the back-end application software is based on C/C++. TELICS provides feedback mechanisms that give the operator good visibility and a quick-look display of the status and modes of instruments as well as data. TELICS has been used for regular science observations since 2008 March on the 2 m, f/10 IUCAA Telescope located at Girawali in Pune, India.

  6. Important aspects of the methodic of using combined aerobics in the process of elementary school pupils' physical education.

    Directory of Open Access Journals (Sweden)

    Globa G.V.

    2011-03-01

    Full Text Available The projective model of system of physical education of pupils with using aerobic technology is scientifically proved. There are represented the theoretical and methodical statements of the methodic. The results of physical preparedness of 1200 pupils were used in this research. Established that the important factor of effectiveness of innovative physical educational methodic is scientifically proved possibility of optimal control of its stage structure.

  7. Control of asperities size and spacing on seismic behavior of subduction megathrusts

    Science.gov (United States)

    Corbi, Fabio; Funiciello, Francesca; Brizzi, Silvia; Lallemand, Serge; Rosenau, Matthias

    2017-08-01

    The majority of the largest subduction megathrust earthquakes share the common characteristic of rupturing more than one asperity along strike of the margin. Understanding the factors that control coseismic failure of multiple asperities, and thus maximum magnitude, is central for seismic hazard assessment. To investigate the role of asperities size and spacing on maximum magnitude, seismicity rate, and percentage of synchronized ruptures, we use analog models simulating along-strike rupture behavior of megathrust earthquakes. We found negative correlations between the barrier-to-asperity length ratio Db/Da and maximum magnitude and seismicity rate. Db/Da also controls the process of asperities synchronization along the megathrust. A permanent barrier behavior is observed for Db/Da > 0.5. Comparing our experimental results to the Nankai Trough historical seismicity, we propose that the distribution of megathrust frictional heterogeneities likely explains the diversity of earthquakes which occurred there.

  8. Size-controllable growth of ZnO nanorods on Si substrate

    Science.gov (United States)

    Yu, Zhentao; Li, Hui; Qiu, Yining; Yang, Xu; Zhang, Wu; Xu, Ning; Sun, Jian; Wu, Jiada

    2017-01-01

    Here we report a simple two-step chemical-solution-based method to grow highly oriented and size-controllable ZnO nanorods on ZnO-seeded Si substrate. The morphology of the grown ZnO nanorods was examined by field emission scanning electron microscopy. The structure was characterized by X-ray diffraction and Raman scattering spectrum. Photoluminescence spectra were measured at room temperature and low temperatures to evaluate the photoluminescence properties of the ZnO nanorods. The grown ZnO nanorods are structured with hexagonal wurtzite. The diameter and length of ZnO nanorods can be controlled by varying the crystal quality of the underlying ZnO seed layers. The crystal quality of the seed layers gets improved as the deposition time and annealing temperature for ZnO seed layers are increased. The effects of annealing on the ZnO nanorods were also studied.

  9. Fabrication and characterization of size-controlled starch-based nanoparticles as hydrophobic drug carriers.

    Science.gov (United States)

    Han, Fei; Gao, Chunmei; Liu, Mingzhu

    2013-10-01

    Acetylated corn starch was successfully synthesized and optimized by the reaction of native corn starch with acetic anhydride and acetic acid in the presence of sulfuric acid as a catalyst. The optimal degree of substitution of 2.85 was obtained. Starch-based nanoparticles were fabricated by a simple and novel nanoprecipitation procedure, by the dropwise addition of water to acetone solution of acetylated starch under stirring. Fourier transform infrared spectrometry showed that acetylated starch had some new bands at 1750, 1375 and 1240 cm(-1) while acetylated starch nanoparticles presented the identical peaks as the drug-loaded acetylated starch nanoparticles and the acetylated starch. Wide angle X-ray diffraction indicated that A-type pattern of native starch was completely transformed into the V-type pattern of Acetylated starch and starch-based nanoparticles show the similar type pattern with the acetylated starch. The scanning electron microscopy showed that the different sizes of pores formed on the acetylated starch granules were utterly converted into the uniform-sized spherical nanoparticles after the nanoprecipitation. The encapsulation efficiency and diameter of nanoparticle can be adjusted by the degree of substitution, the volume ratio of nonsolvent to solvent and the weight ratio of acetylated starch to drug. It was also depicted that the release behaviors of drug-loaded nanoparticles depend on the size of nanoparticles and the degree of substitution of the acetylated starch. Release studies prove that the starch-based nanoparticles with uniform size can be used for the encapsulation of hydrophobic drug and attained the sustained and controllable drug release carriers.

  10. Partner Influence in Diet and Exercise Behaviors: Testing Behavior Modeling, Social Control, and Normative Body Size

    Science.gov (United States)

    Ciciurkaite, Gabriele; Brady, Christy Freadreacea; Garcia, Justin

    2016-01-01

    Previous research has documented social contagion in obesity and related health behaviors, but less is known about the social processes underlying these patterns. Focusing on married or cohabitating couples, we simultaneously explore three potential social mechanisms influencing obesity: normative body size, social control, and behavior modeling. We analyze the association between partner characteristics and the obesity-related health behaviors of focal respondents, comparing the effects of partners’ body type, partners’ attempts to manage respondents’ eating behaviors, and partners’ own health behaviors on respondents’ health behaviors (physical activity, fruit and vegetable consumption, and fast food consumption). Data on 215 partners are extracted from a larger study of social mechanisms of obesity in family and community contexts conducted in 2011 in the United States. Negative binomial regression models indicate that partner behavior is significantly related to respondent behavior (p obesity-related patterns of consumption and physical activity. In contrast, we find little support for the influence of normative body size or partner social control in this sample, though generalizations about the relevance of these processes may be inappropriate. These results underscore the importance of policies and interventions that target dyads and social groups, suggesting that adoption of exercise or diet modifications in one individual is likely to spread to others, creating a social environment characterized by mutual reinforcement of healthy behavior. PMID:28033428

  11. Anodic aluminum oxide with fine pore size control for selective and effective particulate matter filtering

    Science.gov (United States)

    Zhang, Su; Wang, Yang; Tan, Yingling; Zhu, Jianfeng; Liu, Kai; Zhu, Jia

    2016-07-01

    Air pollution is widely considered as one of the most pressing environmental health issues. Particularly, atmospheric particulate matters (PM), a complex mixture of solid or liquid matter suspended in the atmosphere, are a harmful form of air pollution due to its ability to penetrate deep into the lungs and blood streams, causing permanent damages such as DNA mutations and premature death. Therefore, porous materials which can effectively filter out particulate matters are highly desirable. Here, for the first time, we demonstrate that anodic aluminum oxide with fine pore size control fabricated through a scalable process can serve as effective and selective filtering materials for different types of particulate matters (such as PM2.5, PM10). Combining selective and dramatic filtering effect, fine pore size control and a scalable process, this type of anodic aluminum oxide templates can potentially serve as a novel selective filter for different kinds of particulate matters, and a promising and complementary solution to tackle this serious environmental issue.

  12. Large 2D-arrays of size-controllable silver nanoparticles prepared by hybrid deposition

    Science.gov (United States)

    Dieu Thuy Ung, Thi; Hoa Nguyen, Thi; Liem Nguyen, Quang

    2016-09-01

    Two main results are presented in this paper. (i) Silver nanoparticles (AgNPs) with uniform size-distribution and controllability in the range of 20-50 nm were synthesized by seeding and growing at ambient conditions. The single-crystal Ag nano-seeds were created by reduction of AgNO3 in presence of citrate surfactant at 70 °C. Then, importantly, the fresh AgCl precursor was used in the presence of polyvinylpyrrolidone to adjust the reaction rate with ascorbic acid to generate Ag for growing on the surface of single-crystal Ag nano-seeds. The AgNPs size could be well-controlled by varying the amount of Ag nano-seeds while keeping the AgCl precursor concentration to be constant. (ii) The large 2D-arrays with homogeneous and dense monolayers of AgNPs were prepared on ITO substrates by hybrid method, in which the key technological point is the surface functionalization of AgNPs using mixed alkanethiols (dodecanethiol:octadecanethiol = 6:1). We have used the fabricated 2D-arrays from the 50 nm AgNPs as a surface enhanced Raman scattering substrate to take the Raman scattering spectra of rhodamine B (RhB), glucose and viral pathogen (H5N1) at very low concentrations of 10-10 M, 10-12 M and 4 ng μl-1, respectively.

  13. A novel Drosophila Girdin-like protein is involved in Akt pathway control of cell size

    Energy Technology Data Exchange (ETDEWEB)

    Puseenam, Aekkachai [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Yoshioka, Yasuhide [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Venture Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Nagai, Rika [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Hashimoto, Reina [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Venture Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Suyari, Osamu [Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Itoh, Masanobu [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Enomoto, Atsushi [Department of Pathology, Center for Neurological Disease and Cancer, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi 466-8550 (Japan); Takahashi, Masahide [Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Department of Pathology, Center for Neurological Disease and Cancer, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi 466-8550 (Japan); Yamaguchi, Masamitsu, E-mail: myamaguc@kit.ac.jp [Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Insect Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan)

    2009-11-15

    The Akt signaling pathway is well known to regulate cell proliferation and growth. Girdin, a novel substrate of Akt, plays a crucial role in organization of the actin cytoskeleton and cell motility under the control of Akt. We here identified a novel Girdin-like protein in Drosophila (dGirdin), which has two isoforms, dGirdin PA and dGirdin PB. dGirdin shows high homology with human Girdin in the N-terminal and coiled-coil domains, while diverging at the C-terminal domain. On establishment of transgenic fly lines, featuring knockdown or overexpression of dGirdin in vivo, overexpression in the wing disc cells induced ectopic apoptosis, implying a role in directing apoptosis. Knockdown of dGirdin in the Drosophila wing imaginal disc cells resulted in reduction of cell size. Furthermore, this was enhanced by half reduction of the Akt gene dose, suggesting that Akt positively regulates dGirdin. In the wing disc, cells in which dGirdin was knocked down exhibited disruption of actin filaments. From these in vivo analyses, we conclude that dGirdin is required for actin organization and regulation of appropriate cell size under control of the Akt signaling pathway.

  14. Partner Influence in Diet and Exercise Behaviors: Testing Behavior Modeling, Social Control, and Normative Body Size.

    Science.gov (United States)

    Perry, Brea; Ciciurkaite, Gabriele; Brady, Christy Freadreacea; Garcia, Justin

    2016-01-01

    Previous research has documented social contagion in obesity and related health behaviors, but less is known about the social processes underlying these patterns. Focusing on married or cohabitating couples, we simultaneously explore three potential social mechanisms influencing obesity: normative body size, social control, and behavior modeling. We analyze the association between partner characteristics and the obesity-related health behaviors of focal respondents, comparing the effects of partners' body type, partners' attempts to manage respondents' eating behaviors, and partners' own health behaviors on respondents' health behaviors (physical activity, fruit and vegetable consumption, and fast food consumption). Data on 215 partners are extracted from a larger study of social mechanisms of obesity in family and community contexts conducted in 2011 in the United States. Negative binomial regression models indicate that partner behavior is significantly related to respondent behavior (p behavior modeling mechanism in obesity-related patterns of consumption and physical activity. In contrast, we find little support for the influence of normative body size or partner social control in this sample, though generalizations about the relevance of these processes may be inappropriate. These results underscore the importance of policies and interventions that target dyads and social groups, suggesting that adoption of exercise or diet modifications in one individual is likely to spread to others, creating a social environment characterized by mutual reinforcement of healthy behavior.

  15. Designing artificial 2D crystals with site and size controlled quantum dots.

    Science.gov (United States)

    Xie, Xuejun; Kang, Jiahao; Cao, Wei; Chu, Jae Hwan; Gong, Yongji; Ajayan, Pulickel M; Banerjee, Kaustav

    2017-08-30

    Ordered arrays of quantum dots in two-dimensional (2D) materials would make promising optical materials, but their assembly could prove challenging. Here we demonstrate a scalable, site and size controlled fabrication of quantum dots in monolayer molybdenum disulfide (MoS2), and quantum dot arrays with nanometer-scale spatial density by focused electron beam irradiation induced local 2H to 1T phase change in MoS2. By designing the quantum dots in a 2D superlattice, we show that new energy bands form where the new band gap can be controlled by the size and pitch of the quantum dots in the superlattice. The band gap can be tuned from 1.81 eV to 1.42 eV without loss of its photoluminescence performance, which provides new directions for fabricating lasers with designed wavelengths. Our work constitutes a photoresist-free, top-down method to create large-area quantum dot arrays with nanometer-scale spatial density that allow the quantum dots to interfere with each other and create artificial crystals. This technique opens up new pathways for fabricating light emitting devices with 2D materials at desired wavelengths. This demonstration can also enable the assembly of large scale quantum information systems and open up new avenues for the design of artificial 2D materials.

  16. Tectonic controls on earthquake size distribution and seismicity rate: slab buoyancy and slab bending

    Science.gov (United States)

    Nishikawa, T.; Ide, S.

    2014-12-01

    There are clear variations in maximum earthquake magnitude among Earth's subduction zones. These variations have been studied extensively and attributed to differences in tectonic properties in subduction zones, such as relative plate velocity and subducting plate age [Ruff and Kanamori, 1980]. In addition to maximum earthquake magnitude, the seismicity of medium to large earthquakes also differs among subduction zones, such as the b-value (i.e., the slope of the earthquake size distribution) and the frequency of seismic events. However, the casual relationship between the seismicity of medium to large earthquakes and subduction zone tectonics has been unclear. Here we divide Earth's subduction zones into over 100 study regions following Ide [2013] and estimate b-values and the background seismicity rate—the frequency of seismic events excluding aftershocks—for subduction zones worldwide using the maximum likelihood method [Utsu, 1965; Aki, 1965] and the epidemic type aftershock sequence (ETAS) model [Ogata, 1988]. We demonstrate that the b-value varies as a function of subducting plate age and trench depth, and that the background seismicity rate is related to the degree of slab bending at the trench. Large earthquakes tend to occur relatively frequently (lower b-values) in shallower subduction zones with younger slabs, and more earthquakes occur in subduction zones with deeper trench and steeper dip angle. These results suggest that slab buoyancy, which depends on subducting plate age, controls the earthquake size distribution, and that intra-slab faults due to slab bending, which increase with the steepness of the slab dip angle, have influence on the frequency of seismic events, because they produce heterogeneity in plate coupling and efficiently inject fluid to elevate pore fluid pressure on the plate interface. This study reveals tectonic factors that control earthquake size distribution and seismicity rate, and these relationships between seismicity and

  17. A SCARECROW-based regulatory circuit controls Arabidopsis thaliana meristem size from the root endodermis.

    Science.gov (United States)

    Moubayidin, Laila; Salvi, Elena; Giustini, Leonardo; Terpstra, Inez; Heidstra, Renze; Costantino, Paolo; Sabatini, Sabrina

    2016-05-01

    SCARECROW controls Arabidopsis root meristem size from the root endodermis tissue by regulating the DELLA protein RGA that in turn mediates the regulation of ARR1 levels at the transition zone. Coherent organ growth requires a fine balance between cell division and cell differentiation. Intriguingly, plants continuously develop organs post-embryonically thanks to the activity of meristems that allow growth and environmental plasticity. In Arabidopsis thaliana, continued root growth is assured when division of the distal stem cell and their daughters is balanced with cell differentiation at the meristematic transition zone (TZ). We have previously shown that at the TZ, the cytokinin-dependent transcription factor ARR1 controls the rate of differentiation commitment of meristematic cells and that its activities are coordinated with those of the distal stem cells by the gene SCARECROW (SCR). In the stem cell organizer (the quiescent center, QC), SCR directly suppresses ARR1 both sustaining stem cell activities and titrating non-autonomously the ARR1 transcript levels at the TZ via auxin. Here, we show that SCR also exerts a fine control on ARR1 levels at the TZ from the endodermis by sustaining gibberellin signals. From the endodermis, SCR controls the RGA REPRESSOR OF ga1-3 (RGA) DELLA protein stability throughout the root meristem, thus controlling ARR1 transcriptional activation at the TZ. This guarantees robustness and fineness to the control of ARR1 levels necessary to balance cell division to cell differentiation in sustaining coherent root growth. Therefore, this work advances the state of the art in the field of root meristem development by integrating the activity of three hormones, auxin, gibberellin, and cytokinin, under the control of different tissue-specific activities of a single root key regulator, SCR.

  18. Risk-based learning games improve long-term retention of information among school pupils.

    Science.gov (United States)

    Devonshire, Ian M; Davis, Jenny; Fairweather, Sophie; Highfield, Lauren; Thaker, Chandni; Walsh, Ashleigh; Wilson, Rachel; Hathway, Gareth J

    2014-01-01

    Risk heightens motivation and, if used appropriately, may have the potential to improve engagement in the classroom. We have developed a risk-based learning game for school pupils in order to test whether such learning games can improve later recall of information. The study was performed during a series of public engagement workshops delivered by undergraduate students. Undergraduate neuroscience students delivered 90-minute science workshops to 9-10 year old school pupils (n = 448) that were divided into 'Risk', 'No risk' and 'Control' classes. 'Risk' classes received periodic multiple-choice questions (MCQs) during the workshops which required small teams of pupils to assign tokens to the answer(s) they believed to be correct. Tokens assigned to the correct answer were returned to the group and an equal number given back as a prize; tokens assigned to incorrect answers were lost. Participation was incentivised by the promise of a brain-related prize to the team with the most tokens at the end of the workshop. 'No risk' classes received MCQs without the risk component whilst the 'Control' classes received no MCQs. When presented with a neuroscience quiz based on workshop content at the end of the workshop, pupils in the 'Risk' classes exhibited significantly greater recall of information one week later. Quiz scores were higher than scores from the day of the workshop which suggested pupils may have discussed the workshop content outside of the classroom, thereby increasing knowledge over and above what was learned during the workshop. This is supported by feedback from pupils in 'Risk' classes which indicated that 'Risk' workshops were more interesting than 'No risk' and 'Control' workshops. These data suggest that there is a role for risk in the classroom but further investigations are required to elucidate the causal mechanisms of improved retention of information.

  19. Risk-based learning games improve long-term retention of information among school pupils.

    Directory of Open Access Journals (Sweden)

    Ian M Devonshire

    Full Text Available Risk heightens motivation and, if used appropriately, may have the potential to improve engagement in the classroom. We have developed a risk-based learning game for school pupils in order to test whether such learning games can improve later recall of information. The study was performed during a series of public engagement workshops delivered by undergraduate students. Undergraduate neuroscience students delivered 90-minute science workshops to 9-10 year old school pupils (n = 448 that were divided into 'Risk', 'No risk' and 'Control' classes. 'Risk' classes received periodic multiple-choice questions (MCQs during the workshops which required small teams of pupils to assign tokens to the answer(s they believed to be correct. Tokens assigned to the correct answer were returned to the group and an equal number given back as a prize; tokens assigned to incorrect answers were lost. Participation was incentivised by the promise of a brain-related prize to the team with the most tokens at the end of the workshop. 'No risk' classes received MCQs without the risk component whilst the 'Control' classes received no MCQs. When presented with a neuroscience quiz based on workshop content at the end of the workshop, pupils in the 'Risk' classes exhibited significantly greater recall of information one week later. Quiz scores were higher than scores from the day of the workshop which suggested pupils may have discussed the workshop content outside of the classroom, thereby increasing knowledge over and above what was learned during the workshop. This is supported by feedback from pupils in 'Risk' classes which indicated that 'Risk' workshops were more interesting than 'No risk' and 'Control' workshops. These data suggest that there is a role for risk in the classroom but further investigations are required to elucidate the causal mechanisms of improved retention of information.

  20. Control of grain size in sublimation-grown CdTe, and the improvement in performance of devices with systematically increased grain size

    OpenAIRE

    Major, Jonathan; Proskuryakov, Yuri; Durose, Ken; Zoppi, Guillaume; Forbes, Ian

    2010-01-01

    A method to control the grain size of CdTe thin films deposited by close space sublimation using chamber pressure is demonstrated. Grain diameter is shown to increase in the pressure range 2–200 Torr, following the linear relationship D (?m)=0.027×P (Torr)+0.90. A mechanism is proposed to explain the dominance of the 111 preferred orientation in the small-grained, but not the large-grained films. For a series of CdTe/CdS solar cells in which the only variable was grain size, the performance p...

  1. Pupil phase discontinuity measurement: comparison of different wavefront sensing concepts

    Science.gov (United States)

    El Hadi, K.; Sauvage, J.-F.; Dohlen, K.; Fusco, T.; Neichel, B.; Marchis, F.; N'Diaye, M.

    2016-07-01

    The Laboratoire d'Astrophysique de Marseille is involved in the preparation of the E-ELT instrumentation framework: In particular, an ESO-EELT M1 mirror segment (1.5 m) has been demonstrated and different wavefront sensing (WFS) concepts among which Pyramid, Zernike phase mask sensor (ZELDA), Phase diversity or still NL Curvature) are also investigated. Segmented mirrors are widely used today in diverse domains: fiber coupling, laser beam shaping, microscopy or retina imaging. If, these mirrors offer a solution to realize important monolithic sizes for giant telescopes in astronomy, they also raise the problem of segments cophasing and measurement of phase discontinuities. In this work, we aim to investigate a suitable WFS approach for pupil phase discontinuity measurement. Coupling a segmented PTT mirror (Iris AO) with four different WFS (Shack-Hartmann, Quadriwave Lateral Shearing Interferometer, Pyramid and Zernike Phase Mask), we study their sensitivity to segmented pupil: in particular, segment phasing, stability, saturation, flat, or still the addressing mode are then performed and compared.

  2. Preparation and formation mechanisms of metallic particles with controlled size, shape, structure and surface functionality

    Science.gov (United States)

    Lu, Lu

    Due to their excellent conductivity and chemical stability, particles of silver (Ag), gold (Au), copper (Cu) and their alloys are widely used in the electronic industry. Other unique properties extend their uses to the biomedical, optical and catalysis fields. All of these applications rely on particles with well controlled size, morphology, structure, and surface properties. Chemical precipitation from homogeneous solutions was selected as the synthetic route for the investigations described in this work. Based on the evaluation of key process parameters (temperature, reactant concentrations, reactant addition rate, mixing, etc.) the general formation mechanisms of metallic particles in various selected precipitation systems were investigated and elucidated. Five different systems for preparing particles with controlled size, morphology, structure and surface functionality are discussed. The first system involves the precipitation of Ag nanoparticles with spherical and anisotropic (platy or fiber-like) morphology. It will be shown that the formation of a stable Ag/Daxad complex has a significant impact on the reaction kinetics, and that the chromonic properties of Daxad molecules are responsible for the particle anisotropy. In the second system, Au-Ag core-shell nanoparticles were prepared in aqueous solution by a two-step precipitation process. The optical properties of these particles can be tailored by varying the thickness of the Ag shell. It was also determined that the stability of the bimetallic metallic sols depends on the Cl-ion concentration in solution. The third system discussed deals with preparation by the polyol process of well dispersed Cu nanospheres with high crystallinity and excellent oxidation resistance. We show that the heterogeneous nucleation (seeding) approach has significant merit in controlling particle size and uniformity. The functionalization of Au nanoparticle surfaces with glutathione molecules is discussed in the next section. The

  3. As Far as the Eye Can See: Relationship between Psychopathic Traits and Pupil Response to Affective Stimuli.

    Science.gov (United States)

    Burley, Daniel T; Gray, Nicola S; Snowden, Robert J

    2017-01-01

    Psychopathic individuals show a range of affective processing deficits, typically associated with the interpersonal/affective component of psychopathy. However, previous research has been inconsistent as to whether psychopathy, within both offender and community populations, is associated with deficient autonomic responses to the simple presentation of affective stimuli. Changes in pupil diameter occur in response to emotionally arousing stimuli and can be used as an objective indicator of physiological reactivity to emotion. This study used pupillometry to explore whether psychopathic traits within a community sample were associated with hypo-responsivity to the affective content of stimuli. Pupil activity was recorded for 102 adult (52 female) community participants in response to affective (both negative and positive affect) and affectively neutral stimuli, that included images of scenes, static facial expressions, dynamic facial expressions and sound-clips. Psychopathic traits were measured using the Triarchic Psychopathy Measure. Pupil diameter was larger in response to negative stimuli, but comparable pupil size was demonstrated across pleasant and neutral stimuli. A linear relationship between subjective arousal and pupil diameter was found in response to sound-clips, but was not evident in response to scenes. Contrary to predictions, psychopathy was unrelated to emotional modulation of pupil diameter across all stimuli. The findings were the same when participant gender was considered. This suggests that psychopathy within a community sample is not associated with autonomic hypo-responsivity to affective stimuli, and this effect is discussed in relation to later defensive/appetitive mobilisation deficits.

  4. As Far as the Eye Can See: Relationship between Psychopathic Traits and Pupil Response to Affective Stimuli

    Science.gov (United States)

    Gray, Nicola S.; Snowden, Robert J.

    2017-01-01

    Psychopathic individuals show a range of affective processing deficits, typically associated with the interpersonal/affective component of psychopathy. However, previous research has been inconsistent as to whether psychopathy, within both offender and community populations, is associated with deficient autonomic responses to the simple presentation of affective stimuli. Changes in pupil diameter occur in response to emotionally arousing stimuli and can be used as an objective indicator of physiological reactivity to emotion. This study used pupillometry to explore whether psychopathic traits within a community sample were associated with hypo-responsivity to the affective content of stimuli. Pupil activity was recorded for 102 adult (52 female) community participants in response to affective (both negative and positive affect) and affectively neutral stimuli, that included images of scenes, static facial expressions, dynamic facial expressions and sound-clips. Psychopathic traits were measured using the Triarchic Psychopathy Measure. Pupil diameter was larger in response to negative stimuli, but comparable pupil size was demonstrated across pleasant and neutral stimuli. A linear relationship between subjective arousal and pupil diameter was found in response to sound-clips, but was not evident in response to scenes. Contrary to predictions, psychopathy was unrelated to emotional modulation of pupil diameter across all stimuli. The findings were the same when participant gender was considered. This suggests that psychopathy within a community sample is not associated with autonomic hypo-responsivity to affective stimuli, and this effect is discussed in relation to later defensive/appetitive mobilisation deficits. PMID:28118366

  5. Objective lens simultaneously optimized for pupil ghosting, wavefront delivery and pupil imaging

    Science.gov (United States)

    Olczak, Eugene G (Inventor)

    2011-01-01

    An objective lens includes multiple optical elements disposed between a first end and a second end, each optical element oriented along an optical axis. Each optical surface of the multiple optical elements provides an angle of incidence to a marginal ray that is above a minimum threshold angle. This threshold angle minimizes pupil ghosts that may enter an interferometer. The objective lens also optimizes wavefront delivery and pupil imaging onto an optical surface under test.

  6. Objective Lens Optimized for Wavefront Delivery, Pupil Imaging, and Pupil Ghosting

    Science.gov (United States)

    Olzcak, Gene

    2009-01-01

    An interferometer objective lens (or diverger) may be used to transform a collimated beam into a diverging or converging beam. This innovation provides an objective lens that has diffraction-limited optical performance that is optimized at two sets of conjugates: imaging to the objective focus and imaging to the pupil. The lens thus provides for simultaneous delivery of a high-quality beam and excellent pupil resolution properties.

  7. Diagnostics of Pupils' Attitude to Education

    Science.gov (United States)

    Eminli, Tovuz

    2011-01-01

    The paper is devoted to the investigation of the questions connected with the pedagogical diagnostics, in particular, the diagnostics of pupils' attitude to education. It is considered reasonable to apply the practice of development of an individual pedagogical and psychological map for productive implementation of the pedagogical diagnostics and…

  8. Psychometric aspects of pupil monitoring systems

    NARCIS (Netherlands)

    Glas, Cees A.W.; Geerlings, Hanneke

    2009-01-01

    Pupil monitoring systems support the teacher in tailoring teaching to the individual level of a student and in comparing the progress and results of teaching with national standards. The systems are based on the availability of an item bank calibrated using item response theory. The assessment of th

  9. Experimental Economics method to study pupils motivation

    OpenAIRE

    Lionel Page

    2010-01-01

    Experimental Economics provide a new set of tools in the tool box of the education economist. This paper review why experimental method may be useful to study how pupils behaviour, formed from their preference and beliefs, may influence their success or failure at school, what are its advantages and what are its limits. Behavioural Economics - Education - Public Policy

  10. North Yorkshire Schools' Responses to Pupil Bereavement

    Science.gov (United States)

    Holland, John; McLennan, Derek

    2015-01-01

    This was a research project carried out in North Yorkshire schools by the loss and bereavement research group of the Educational Psychology Service. The background was an interest in how schools responded to bereaved pupils, whether they had a structured response, trained staff and training needs, from where they sought support and the level of…

  11. Curricular Content for Pupils' Mental Health

    Science.gov (United States)

    Ebadi, Seyed Hossein; Keshtiaray, Narges; Aghaei, Asghar; Yousefy, Alireza

    2016-01-01

    Present-day curricular designs have to take the pupils' psychological needs in account, thus becoming melodies of mental health and happiness for the next generation. Emphasizing the findings from previous investigations using the research synthesis methodology, the present study has been conducted aiming at achieving some integrative knowledge…

  12. Class composition influences on pupils' cognitive development

    NARCIS (Netherlands)

    Peetsma, T.; van der Veen, I.; Koopman, P.; van Schooten, E.

    2006-01-01

    The proportion of low-achieving children in a class can affect the progress of individual pupils in that class. Having a large proportion of low achievers in a class could slow down growth in cognitive achievement but, might also boost such growth, due to the effects of specialist teaching geared to

  13. Manual for School Administrators on Pupil Transportation.

    Science.gov (United States)

    Tennessee State Dept. of Education, Nashville.

    Guiding principles, state laws, and state board rules and regulations are covered, providing school administrators with a ready reference in the field of pupil transportation. Divided into three sections, the manual initially covers administrative procedures including--(1) the purchase of buses, (2) bus maintenance, (3) employment of drivers, (4)…

  14. Pupil Masks for Spectrophotometry of Transiting Exoplanets

    Science.gov (United States)

    Itoh, Satoshi; Matsuo, Taro; Goda, Shohei; Shibai, Hiroshi; Sumi, Takahiro

    2017-09-01

    Spectrophotometric stability, which is crucial in the spectral characterization of transiting exoplanets, is affected by photometric variations arising from field-stop loss in space telescopes with pointing jitter or primary mirror deformation. This paper focuses on a new method for removing slit-loss or field-stop-loss photometric variation through the use of a pupil mask. Two types of pupil function are introduced: the first uses conventional (e.g., Gaussian or hyper-Gaussian) apodizing patterns; whereas the second, which we call a block-shaped mask, employs a new type of pupil mask designed for high photometric stability. A methodology for the optimization of a pupil mask for transit observations is also developed. The block-shaped mask can achieve a photometric stability of 10-5 for a nearly arbitrary field-stop radius when the pointing jitter is smaller than approximately 0.7λ /D and a photometric stability of 10-6 at a pointing jitter smaller than approximately 0.5λ /D. The impact of optical aberrations and mask imperfections upon mask performance is also discussed.

  15. Class composition influences on pupils' cognitive development

    NARCIS (Netherlands)

    Peetsma, T.; van der Veen, I.; Koopman, P.; van Schooten, E.

    2006-01-01

    The proportion of low-achieving children in a class can affect the progress of individual pupils in that class. Having a large proportion of low achievers in a class could slow down growth in cognitive achievement but, might also boost such growth, due to the effects of specialist teaching geared to

  16. Motivating Pupils To Learn in Mathematics.

    Science.gov (United States)

    Ediger, Marlow

    The mathematics teacher has a major responsibility in assisting pupils to learn in ongoing lessons and units of study. This paper discusses ways of motivating students in the mathematics classroom from the perspectives of different learning theories such as behaviorism, humanism, cognitive psychology, and constructivism. Guidelines for teaching…

  17. How Finland Serves Gifted and Talented Pupils

    Science.gov (United States)

    Tirri, Kirsi; Kuusisto, Elina

    2013-01-01

    The purpose of this article is to provide an overview of the ways gifted and talented pupils are served in Finland. The trend toward individualism and freedom of choice as well as national policy affecting gifted education are discussed. Empirical research on Finnish teachers' attitudes toward gifted education with respect to the national…

  18. Shared Reading, the Pupil, and the Teacher

    Science.gov (United States)

    Ediger, Marlow

    2011-01-01

    Pupil/teacher interaction provides opportunities for many kinds of learning experiences. Within the reading curriculum, there are a plethora of activities in oral communication and working together harmoniously. Thus from every day experiences, the teacher may communicate verbally what he/she has read in an interesting, informative manner on the…

  19. Empowering Primary School Pupils through Literacy Remediation ...

    African Journals Online (AJOL)

    FIRST LADY

    often fail to engage the pupils in activities that promote literacy development. The result .... literacy skills for effective learning, the researchers used the vacation reading .... Print Referencing involves both verbal and non-verbal cues used to draw ... a shiny red bucket that performs many functions but on getting old and tired.

  20. Arrays of size and distance controlled platinum nanoparticles fabricated by a colloidal method

    Science.gov (United States)

    Manzke, Achim; Vogel, Nicolas; Weiss, Clemens K.; Ziener, Ulrich; Plettl, Alfred; Landfester, Katharina; Ziemann, Paul

    2011-06-01

    Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles. Subsequent application of plasma etching and annealing steps allows complete removal of the PS carriers and in parallel nucleation and growth of Pt nanoparticles (NPs) which are located at the original center of the PS colloids. In this way, hexagonally arranged spherical Pt NPs are obtained with controlled size and interparticle distances demonstrating variability and precision with so far unknown parameter scalability. This control is demonstrated by the fabrication of Pt NP arrays at a fixed particle distance of 185 nm while systematically varying the diameters between 8 and 15 nm. Further progress could be achieved by seeded emulsion polymerization. Here, Pt loaded PS colloids of 130 nm were used as seeds for a subsequent additional emulsion polymerization, systematically enlarging the diameter of the PS particles. Applying the plasma and annealing steps as above, in this way hexagonally ordered arrays of 9 nm Pt NPs could be obtained at distances up to 260 nm. To demonstrate their stability, such Pt particles were used as etching masks during reactive ion etching thereby transferring their hexagonal pattern into the Si substrate resulting in corresponding arrays of nanopillars.Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles

  1. Secondary school pupils' food choices around schools in a London borough: Fast food and walls of crisps.

    Science.gov (United States)

    Caraher, M; Lloyd, S; Mansfield, M; Alp, C; Brewster, Z; Gresham, J

    2016-08-01

    The objective was to observe and document food behaviours of secondary school pupils from schools in a London borough. The research design combined a number of methods which included geographic information system (GIS) mapping of food outlets around three schools, systemised observations of food purchasing in those outlets before, during and after school, and focus groups conducted with pupils of those schools to gather their views in respect to those food choices. Results are summarised under the five 'A's of Access, Availability, Affordability and Acceptability & Attitudes: Access in that there were concentrations of food outlets around the schools. The majority of pupil food purchases were from newsagents, small local shops and supermarkets of chocolate, crisps (potato chips), fizzy drinks and energy drinks. Availability of fast food and unhealthy options were a feature of the streets surrounding the schools, with 200 m the optimal distance pupils were prepared to walk from and back to school at lunchtime. Affordability was ensured by the use of a consumer mentality and pupils sought out value for money offers; group purchasing of 'two for one' type offers encouraged this trend. Pupils reported healthy items on sale in school as expensive, and also that food was often sold in smaller portion sizes than that available from external food outlets. Acceptability and Attitudes, in that school food was not seen as 'cool', queuing for school food was not acceptable but queuing for food from takeaways was not viewed negatively; for younger pupils energy drinks were 'cool'. In conclusion, pupils recognised that school food was healthier but provided several reasons for not eating in school related to the five 'A's above.

  2. Hypofractionated Radiotherapy for Small-sized Hepatocellular Carcinoma as Salvage Therapy: Sustained Local Control and Safety

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Sun Hyun; Park, Hee Chul; Lim, Do Hoon; Lee, Jung Ae; Choi, Moon Seok; Lee, Joon Hyoek; Koh, Kwang Cheol; Paik, Seung Woon; Yoo, Byung Chul [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2010-11-15

    To evaluate the rate of tumor response, local control, and treatment-related complications after hypofractionated radiotherapy for recurrent hepatocelluar carcinoma (HCC) less than 5 cm in size. Among the HCC patients who were treated by radiotherapy (RT) between 2006 and 2007 after the failure of previous treatment, a total of 12 patients were treated with hypofractionated RT. The criteria for hypofractionated RT was as follows: 1) HCC less than 5 cm, 2) HCC not adjacent to a critical organ, 3) HCC without portal vein tumor thrombosis, and 4) less than 15% of normal liver volume that irradiated 50% of the prescribed dose. Hypofractionated RT was performed with 50 Gy delivered in 10 fractions, at a rate of 5 fractions per week. The evaluation of tumor response was determined by CT scans performed at 3 months after the cessation of RT, followed by the evaluation of toxicity by Common Terminology Criteria for Adverse Events version 3.0. The median follow-up period after radiotherapy was 18 months. A complete response (CR) was achieved in 5 of 12 lesions (41.7%) at CT performed at 3 months after the cessation, whereas the overall complete response was observed in 7 of 12 cases (58.3%). In-field local control rate was sustained in 83.3% of patients. All patients developed intra-hepatic metastases except for 2 patients. The overall survival rate was 90.0% at 1 year and 67.5% at 2 years, respectively. Three patients developed Grade 1 nausea during RT and 1 patient showed a progression of ascites after RT. There was no grade 3 or greater treatment-related toxicities. Hypofractionated RT for small-sized HCC as a salvage therapy showed a 58.3% CR rate and 83.3% of local control. Fifty Gy administered in 10 fractions of partial liver irradiation is considered as a tolerable dose that does not cause severe complications.

  3. Pupil movements to light and accommodative stimulation - A comparative study.

    Science.gov (United States)

    Semmlow, J.; Stark, L.

    1973-01-01

    Isolation and definition of specific response components in pupil reflexes through comparison of the dynamic features of light-induced and accommodation-induced pupil movements. A quantitative analysis of the behavior of the complex nonlinear pupil responses reveals the presence of two independent nonlinear characteristics: a range-dependent gain and a direction dependence or movement asymmetry. These nonlinear properties are attributed to motor processes because they are observable in pupil responses to both light and accommodation stimuli. The possible mechanisms and consequences of these pupil response characteristics are quantitatively defined and discussed.

  4. Structure Sensitivity Study of Waterborne Contaminant Hydrogenation Using Shape- and Size-Controlled Pd Nanoparticles

    KAUST Repository

    Shuai, Danmeng

    2013-03-01

    Catalytic reduction with Pd has emerged as a promising technology to remove a suite of contaminants from drinking water, such as oxyanions, disinfection byproducts, and halogenated pollutants, but low activity is a major challenge for application. To address this challenge, we synthesized a set of shape- and size-controlled Pd nanoparticles and evaluated the activity of three probe contaminants (i.e., nitrite, N-nitrosodimethylamine (NDMA), and diatrizoate) as a function of facet type (e.g., (100), (110), (111)), ratios of low- to high-coordination sites, and ratios of surface sites to total Pd (i.e., dispersion). Reduction results for an initial contaminant concentration of 100 μM show that initial turnover frequency (TOF0) for nitrite increases 4.7-fold with increasing percent of (100) surface Pd sites (from 0% to 95.3%), whereas the TOF0 for NDMA and for diatrizoate increases 4.5- and 3.6-fold, respectively, with an increasing percent of terrace surface Pd sites (from 79.8% to 95.3%). Results for an initial nitrite concentration of 2 mM show that TOF0 is the same for all shape- and size-controlled Pd nanoparticles. Trends for TOF0 were supported by results showing that all catalysts but one were stable in shape and size up to 12 days; for the exception, iodide liberation in diatrizoate reduction appeared to be responsible for a shape change of 4 nm octahedral Pd nanoparticles. Density functional theory (DFT) simulations for the free energy change of hydrogen (H2), nitrite, and nitric oxide (NO) adsorption and a two-site model based on the Langmuir-Hinshelwood mechanism suggest that competition of adsorbates for different Pd sites can explain the TOF0 results. Our study shows for the first time that catalytic reduction activity for waterborne contaminant removal varies with the Pd shape and size, and it suggests that Pd catalysts can be tailored for optimal performance to treat a variety of contaminants for drinking water. © 2013 American Chemical Society.

  5. Substrate size rather than heterogeneity controls downstream travel time distributions in replicate small streams

    Science.gov (United States)

    Aubeneau, A. F.; Hanrahan, B.; Tank, J. L.; Bolster, D.

    2013-12-01

    Dissolved solutes are exported from watersheds with water flow and fluxes are therefore influenced by advection, that carries them further, but also retention processes, that delay their travel. It is especially important to understand the factors controlling network solute retention for biogeoreactive species that can be processed if afforded extended residence. In alluvial systems, substrate characteristics play a crucial role in slowing downstream transport. The roughness size (i.e., grain size relative to water depth) is associated with the distortion of the velocity profile and therefore is related to short term delays from additional dispersion. Surface and subsurface water also continually turn over, creating longer delays in the slow-flowing hyporheic region below the water/sediment interface. Sediment structure could also control transport, as pockets of slower hydraulic conductivity may influence the longest travel times. We present results from multiple solute injection experiments testing the influence of sediment size (pea gravel vs. coarse gravel) and heterogeneity (alternating sections vs. well mixed) on solute transport dynamics in four experimental streams located at the Notre Dame Linked Experimental Ecosystem Facility (ND-LEEF). We show that the stream with homogeneously coarse gravel induced more short-term delays but less long-term retention than the stream with smaller pea gravel. Inverse modeling suggested that the short-term delays were exponentially distributed while the long-term retention followed a truncated power-law behavior. Even though transport in all four streams was anomalous, the scaling truncation time was influenced by sediment size, with the smaller pea gravel exhibiting scaling longer than the coarse gravel. Streams with heterogeneous substrate had an intermediate cut-off. These results uniquely associate transport scaling in fluvial systems and substrate characteristics. The streams revealed truncation timescales that had

  6. Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene.

    Science.gov (United States)

    Ogoshi, Tomoki; Yoshikoshi, Kumiko; Sueto, Ryuta; Nishihara, Hirotomo; Yamagishi, Tada-Aki

    2015-05-26

    We report a new synthesis method of fibrous carbon material with pores sizes that are precisely controlled at the Ångstrom level, by carbonization of two dimensional (2D) porous sheets of pillar[6]arenes. The 2D porous sheets were prepared by 2D supramolecular polymerization induced by oxidation of hydroquinone units of pillar[6]arenes. Owing to the hexagonal structure of pillar[6]arene, the assembly induced by 2D supramolecular polymerization gave hexagonal 2D porous sheets, and the highly ordered structure of the 2D porous sheets formed regular fibrous structures. Then, carbonization of the 2D porous sheets afforded fibrous carbon materials with micropores. The micropore size of the fibrous porous carbon prepared from pillar[6]arene was the same size as that of the starting material pillar[6]arene assembly.

  7. Do normal pupil diameter differences in the population underlie the color selection of #thedress?

    Science.gov (United States)

    Vemuri, Kavita; Bisla, Kulvinder; Mulpuru, SaiKrishna; Varadharajan, Srinivasa

    2016-03-01

    The fundamental question that arises from the color conundrum of #thedress is "What are the phenomena that underlie the individual differences in the reported colors when all other conditions like light and device for the display are identical?" A survey of 384 participants showed near-equal distribution into blue/black (b/b) and white/gold (w/g) groups. We looked at pupil size differences in a sample population of 53 individuals from these two groups and a group that switched from w/g to b/b. Our results showed that the w/g and switch groups had significantly lower pupil size than the b/b group (w/gpupil size. A standard infinity focus experiment was then conducted on 18 participants from each group to check if there is bimodality in the population, and we found a statistically significant difference (w/gpupil size by 3-4 mm, but the participants did not report a switch. The results suggest a population difference in normal pupil size influencing color observation which was exposed by the dress.

  8. The Manchester Color Wheel: validation in secondary school pupils

    Directory of Open Access Journals (Sweden)

    Carruthers Helen R

    2012-09-01

    Full Text Available Abstract Background As part of our research programme into facilitating improved ways of communicating with patients, especially about more sensitive clinical issues, we have been investigating whether there are any non-verbal methods that might aid this process. One such approach is to ask patients to choose a color in response to a particular question, for instance about health or psychological status, and for this purpose we developed the Manchester Color Wheel (MCW. This instrument consists of positive, neutral and negative colors and its validation in normal adults and those with anxiety or depression showed that it is responsive to change and reproducible. It also has the capacity to identify a positive frame of mind. We concluded that it might be a particularly useful instrument in adolescents and therefore this study aimed to validate it in a secondary school. Methods 620 pupils (aged 11–17 years, mean age 14.0 years, 298 (48.1% males, 322 (51.9% females at Sale Grammar School in Greater Manchester were asked to relate their mood to a MCW color and also complete the Hospital Anxiety Depression (HAD questionnaire. To give these pupils an experience in science, 197 were divided into four subgroups for an ‘experiment’ to ascertain whether, compared to controls, a change in mood color choice could be induced by participation in sport, music or art activities. Results Although mood color and HAD depression score are unlikely to be measuring exactly the same psychological state, a negative mood color was chosen by 62.5% of HAD depressed compared to only 14.5% of HAD normal pupils (p  Conclusion This study confirms the potential utility of the MCW to rapidly and easily assess a variety of health issues in large populations, including adolescents. Some of our results should also be of interest to educationalists.

  9. 氨法制取纳米氧化锌的粒径控制研究%Particle size control of nano - sized zinc oxide by ammonia process

    Institute of Scientific and Technical Information of China (English)

    蔡建国; 蔡睿敏

    2009-01-01

    为有效控制氨法制取纳米氧化锌的粒径,在蒸氨前将浸出原液用一定量的纯净水稀释,可增加初期沉淀生成的晶核数,使沉淀粒径更加均匀和细化,同时发现蒸氨残液不可以作为浸出原液的稀释剂回用.蒸氨的加热方式对纳米氧化锌的粒径也有影响,选择蒸汽直接加热,当溶液含锌质量浓度小于0.3 g/L时,所制取的纳米氧化锌粒径满足GB/T 19589-2004纳米氧化锌的要求 .%In order to effectively control the particle size of nano - sized zinc oxide prepared by ammonia process,leaching stock solution was diluted with a certain amount of purified water before ammonia distillation process,which could increase the quantity of crystal nucleus generated by initial precipitation and make particle size of precipitate more uniform and refined.Meanwhile,it was found that distilled ammonia residual liquid could not be served as diluent of leaching stock solution for recycling.Also,heating method of ammonia distillation will affect the particle size of nano - sized zinc oxide.Particle size of prepared nano - sized zinc oxide can satisfy the requirements of GB/T 19589-2004,when direct steam heating was selected and mass concentration of zinc in the solution was less than 0.3 g/L.

  10. Size-Controlled Synthesis of CoFe2O4 Nanoparticles Potential Contrast Agent for MRI and Investigation on Their Size-Dependent Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Fujun Liu

    2013-01-01

    Full Text Available Cobalt ferrite nanoparticles (CoFe2O4 NPs were synthesized by coprecipitation followed by treatments with diluted nitric acid and sodium citrate. Transmission electron microscope (TEM and photon correlation spectroscopy (PCS characterization showed that the size distributions of these nanoparticles were monodisperse and that no aggregation occurred. This colloid showed a long-term stability. Through adjustment of the concentrations of reactants and reaction temperature, the size of the NPs can be tuned from 6 to 80 nm. The size-control mechanism is explained by a nucleation-growth model, where the local concentration of monomers is assumed to decide the size of nuclei, and reaction temperatures influence the growth of nuclei. Magnetization and relaxivity r1,2 measurements showed that the NPs revealed size-dependent magnetization and relaxivity properties, which are explained via a “dead magnetic layer” theory where reductions of saturation magnetization (Ms and r1,2 are assumed to be caused by the demagnetization of surface spins.

  11. Maternal Diet and Insulin-Like Signaling Control Intergenerational Plasticity of Progeny Size and Starvation Resistance.

    Directory of Open Access Journals (Sweden)

    Jonathan D Hibshman

    2016-10-01

    Full Text Available Maternal effects of environmental conditions produce intergenerational phenotypic plasticity. Adaptive value of these effects depends on appropriate anticipation of environmental conditions in the next generation, and mismatch between conditions may contribute to disease. However, regulation of intergenerational plasticity is poorly understood. Dietary restriction (DR delays aging but maternal effects have not been investigated. We demonstrate maternal effects of DR in the roundworm C. elegans. Worms cultured in DR produce fewer but larger progeny. Nutrient availability is assessed in late larvae and young adults, rather than affecting a set point in young larvae, and maternal age independently affects progeny size. Reduced signaling through the insulin-like receptor daf-2/InsR in the maternal soma causes constitutively large progeny, and its effector daf-16/FoxO is required for this effect. nhr-49/Hnf4, pha-4/FoxA, and skn-1/Nrf also regulate progeny-size plasticity. Genetic analysis suggests that insulin-like signaling controls progeny size in part through regulation of nhr-49/Hnf4, and that pha-4/FoxA and skn-1/Nrf function in parallel to insulin-like signaling and nhr-49/Hnf4. Furthermore, progeny of DR worms are buffered from adverse consequences of early-larval starvation, growing faster and producing more offspring than progeny of worms fed ad libitum. These results suggest a fitness advantage when mothers and their progeny experience nutrient stress, compared to an environmental mismatch where only progeny are stressed. This work reveals maternal provisioning as an organismal response to DR, demonstrates potentially adaptive intergenerational phenotypic plasticity, and identifies conserved pathways mediating these effects.

  12. Shape-and size-controlled Ag nanoparticles stabilized by in situ generated secondary amines

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Meneses, E., E-mail: esther.ramirez@ibero.mx [Departamento de Ingeniería y Ciencias Químicas, Universidad Iberoamericana, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, Distrito Federal C.P. 01219 (Mexico); Montiel-Palma, V. [Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos C.P. 62209 (Mexico); Domínguez-Crespo, M.A.; Izaguirre-López, M.G. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada-IPN, Unidad Altamira. Km 14.5 Carretera Tampico-Puerto Industrial, 89600 Altamira, Tamaulipas (Mexico); Palacios-Gonzalez, E. [Laboratorio de Microscopia de Ultra alta Resolución, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas No. 152, C.P. 07730 México D.F. (Mexico); Dorantes-Rosales, H. [Departamento de Metalurgia, E.S.I.Q.I.E.-I.P.N., Unidad Profesional Adolfo López Mateos, Zacatenco, Delegación. Gustavo A. Madero, C.P. 07738 México D.F. (Mexico)

    2015-09-15

    Highlights: • Ag nanoparticles were generated from Ag amido complexes AgN{sup i}Pr{sub 2} and AgN(SiMe{sub 3}){sub 2}. • Ag nanoparticles were stabilized by in situ generated HN{sup i}Pr{sub 2} or HN(SiMe{sub 3}){sub 2}. • 1 or 5 equiv. of ethylenediamine as additional capping agent decreases the average size of the particles. • Ethylenediamine favor the formation of spherical particles. - Abstract: Silver amides such as AgN{sup i}Pr{sub 2} and AgN(SiMe{sub 3}){sub 2} have been employed successfully as precursors for the yield synthesis of silver nanoparticles under mild conditions of dihydrogen gas reduction (2 atm) in organic media. Transmission electron microscopy (TEM) showed the formation of silver nanoparticles with FCC structure, variously sized from 26 to 35 nm for AgN{sup i}Pr{sub 2} and from 14 to 86 nm for AgN(SiMe{sub 3}){sub 2}, the synthesis could take place in absence of added stabilizers due to the in situ formation of secondary amines from the reaction of dihydrogen gas with the amide ligands of the silver precursor. Indeed, the presence of HNR{sub 2} (R = iPr{sub 2}, N(SiMe{sub 3}){sub 2}) on the surface of the nanoparticle was confirmed by spectroscopic means. Finally, the addition of ethylenediamine as additional capping agent allowed not only the control of the structural characteristics of the resulting Ag nanoparticles (well-dispersed with spherical shape), but that regarding the nanoparticle size as it inhibited overgrowth, limiting it to ca. 25 nm.

  13. Multiple coaxial foci generation by phase-only pupil filters

    Science.gov (United States)

    Valle, Pedro J.; Oti, José E.; Canales, Vidal F.; Cagigal, Manuel P.

    2007-04-01

    A new procedure for creating simultaneous multiple foci along the same optical axis with phase-only pupil-plane filters is proposed. Pupil-plane filters consist in phase-only masks described by simple circularly symmetric analytical functions. The axial separation between foci and their energy distribution are independently controlled by two different parameters of the filter. The main advantage of this new design is that, unlike other methods that required slow iterative algorithms, the proposed phase masks are straightforwardly calculated from analytical expressions. Moreover, real-time dynamic foci control could be achieved by using a computer addressed spatial light modulator that allowed the generation of variable phase patterns. The phase profiles we propose can be combined with multiple transversal foci phase patterns to actually form axial replicas of the transversal foci. Thus, it should be expected that three-dimensional structures were dynamically driven fast enough to perform real-time interactive multiple foci manipulation. Experimental verification of the multiple coaxial foci creation by static phase filters is shown.

  14. Gripe water as reducing and stabilizing agent for synthesis of size controlled gold nanoparticles.

    Science.gov (United States)

    Kirubha, E; Palanisamy, P K

    2013-03-01

    Green synthesis techniques are emerging as more facile and eco-friendly approach for the synthesis of metal nanoparticles compared to chemical reduction methods. Herein we report a new approach to synthesize gold nanoparticles (AuNPs) using gripe water as a reducing as well as stabilizing agent. Good control over the size of the nanoparticles from 3.2 nm to 25 nm has been achieved with this method by simply varying the experimental conditions. The Surface Plasmon Resonance bands of tunable gold nanospheres with high monodispersity and polydispersity have been obtained by this technique and monitored using UV-Visible spectrum. The morphology and the size of these AuNPs are determined using High Resolution Transmission Electron Microscope (HR-TEM). X-Ray Diffraction (XRD) analysis confirms the crystalline nature and the phase of the AuNPs. The as-synthesized AuNPs exhibit good optical nonlinearity. The nonlinear optical studies have been carried out by Z-scan technique to demonstrate its optical limiting property. The threshold limit of the AuNPs is obtained at a input intensity of 30 mW. The nonlinear refractive index of the nanoparticles is in the order of 10(-9) cm2/W and the third-order nonlinearity is estimated to be 7 x 10(-5) esu.

  15. Biosynthesis of Inorganic Nanoparticles: A Fresh Look at the Control of Shape, Size and Composition

    Directory of Open Access Journals (Sweden)

    Si Amar Dahoumane

    2017-02-01

    Full Text Available Several methodologies have been devised for the design of nanomaterials. The “Holy Grail” for materials scientists is the cost-effective, eco-friendly synthesis of nanomaterials with controlled sizes, shapes and compositions, as these features confer to the as-produced nanocrystals unique properties making them appropriate candidates for valuable bio-applications. The present review summarizes published data regarding the production of nanomaterials with special features via sustainable methodologies based on the utilization of natural bioresources. The richness of the latter, the diversity of the routes adopted and the tuned experimental parameters have led to the fabrication of nanomaterials belonging to different chemical families with appropriate compositions and displaying interesting sizes and shapes. It is expected that these outstanding findings will encourage researchers and attract newcomers to continue and extend the exploration of possibilities offered by nature and the design of innovative and safer methodologies towards the synthesis of unique nanomaterials, possessing desired features and exhibiting valuable properties that can be exploited in a profusion of fields.

  16. Size control of semimetal bismuth nanoparticles and the UV-visible and IR absorption spectra.

    Science.gov (United States)

    Wang, Y W; Hong, Byung Hee; Kim, Kwang S

    2005-04-21

    We introduced a simple chemical method to synthesize semimetal bismuth nanoparticles in N,N-dimethylformamide (DMF) by reducing Bi(3+) with sodium borohydride (NaBH(4)) in the presence of poly(vinylpyrroldone) (PVP) at room temperature. The size and dispersibility of Bi nanoparticles can be easily controlled by changing the synthetic conditions such as the molar ratio of PVP to BiCl(3) and the concentration of BiCl(3). The UV-visible absorption spectra of Bi nanoparticles of different diameters are systematically studied. The surface plasmon peaks broaden with the increasing molar ratio of PVP to BiCl(3) as the size of bismuth nanoparticles decreases. Infrared (IR) spectra of the complexes with different molar ratios of PVP/BiCl(3) show a strong interaction between the carboxyl oxygen (C=O) of PVP and Bi(3+) ion and a weak interaction between the carboxyl oxygen (C=O) of PVP and the Bi atom in nanoparticles. This indicates that PVP serves as an effective capping ligand, which prevents the nanoparticles from aggregation.

  17. Regenerated silk fibroin films with controllable nanostructure size and secondary structure for drug delivery.

    Science.gov (United States)

    Zhou, Juan; Zhang, Bin; Shi, Lijun; Zhong, Jian; Zhu, Jun; Yan, Juan; Wang, Ping; Cao, Chuanbao; He, Dannong

    2014-12-24

    The ability of drug release from SF materials was governed largely by their secondary structure. It is known that the breakage degree of the peptide chain during the silk fibroin (SF) dissolution can affect the structure, property, and applications of SF materials. To deeply understand this effect, we designed a reaction system based on CaCl2/H2O/C2H5OH ternary solvent with different ethanol content to obtain the regenerated SF films with different morphologies and secondary structures. The results showed that the globule-like nanostructure was observed in all regenerated SF films, and their size decreased significantly with reducing the ethanol content in the solvent. Correspondingly, the β-sheet structure content of the SF films increased. In addition, the contact angle and the elongation ratio increased, and water absorption decreased significantly with decreasing the ethanol content in the solvent. The accumulated release percents of doxorubicin from these SF films were significantly different with increasing the time. With smaller nanostructure size and more β-sheet content, the SF films had a slower drug release at the beginning. This study indicated the importance of the ethanol content in the solvent in controlling the structure and properties of the regenerated SF films, which would improve the application of SF in drug delivery.

  18. High efficiency and low cost preparation of size controlled starch nanoparticles through ultrasonic treatment and precipitation.

    Science.gov (United States)

    Chang, Yanjiao; Yan, Xiaoxia; Wang, Qian; Ren, Lili; Tong, Jin; Zhou, Jiang

    2017-07-15

    The purpose of this work was to develop an approach to produce size controlled starch nanoparticles (SNPs), via precipitation with high efficiency and low cost. High concentration starch aqueous pastes (up to 5wt.%) were treated by ultrasound. Viscosity measurements and size exclusion chromatography characterization revealed that, after 30min ultrasonic treatment, viscosity of the starch pastes decreased two orders of magnitude and the weight average molecular weight of the starch decreased from 8.4×10(7) to 2.7×10(6)g/mol. Dynamic light scattering measurements and scanning electron microscopy observations showed that the SNPs prepared from the starch pastes with ultrasonic treatments were smaller (∼75nm) and more uniform. Moreover, SNPs could be obtained using less non-solvents. X-ray diffraction results indicated that effect of the ultrasonic treatment on crystalline structure of the SNPs was negligible. Ultrasound can be utilized to prepare smaller SNPs through nanoprecipitation with higher efficiency and lower cost. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Preparation of Size-Controlled Silver Nanoparticles and Chitin-Based Composites and Their Antimicrobial Activities

    Directory of Open Access Journals (Sweden)

    Vinh Quang Nguyen

    2013-01-01

    Full Text Available A simple method for the preparation of size-controlled spherical silver nanoparticles (Ag NPs was reported for their generation by autoclaving a mixture of silver-containing glass powder and glucose. The particle size is regulated by the glucose concentration, with concentrations of 0.25, 1.0, and 4.0 wt% glucose providing small (3.48±1.83 nm in diameter, medium (6.53±1.78 nm, and large (12.9±2.5 nm particles, respectively. In this study, Ag NP/chitin composites were synthesized by mixing each of these three Ag NP suspensions with a <5% deacetylated (DAc chitin powder (pH 7.0 at room temperature. The Ag NPs were homogenously dispersed and stably adsorbed onto the chitin. The Ag NP/chitin composites were obtained as yellow or brown powders. Approximately 5, 15, and 20 μg of the small, medium, and large Ag NPs, respectively, were estimated to maximally adsorb onto 1 mg of chitin. The bactericidal and antifungal activities of the Ag NP/chitin composites increased as the amount of Ag NPs in the chitin increased. Furthermore, smaller Ag NPs (per weight in the chitin composites provided higher bactericidal and anti-fungal activities.

  20. Immunosuppressive Activity of Size-Controlled PEG-PLGA Nanoparticles Containing Encapsulated Cyclosporine A

    Directory of Open Access Journals (Sweden)

    Li Tang

    2012-01-01

    Full Text Available We encapsulated cyclosporine A (CsA in poly(ethylene glycol-b-poly(d,l-lactide-co-glycolide (PEG-PLGA nanoparticles (NPs by nanoprecipitation of CsA and PEG-PLGA. The resulting CsA/PEG-PLGA-NPs were <100 nm in diameter with a narrow particle size distribution. The NP size could be controlled by tuning the polymer concentration, solvent, or water/solvent ratio during formulation. The PEGylated NPs maintained non-aggregated in salt solution. Solid NPs lyoprotected with bovine serum albumin were prepared for the convenience of storage and transportation. The release kinetics of CsA (55.6% released on Day 1 showed potential for maintaining therapeutic CsA concentrations in vivo. In T-cell assays, both free CsA and CsA/PEG-PLGA-NPs suppressed T-cell proliferation and production of inflammatory cytokines dose dependently. In a mixed lymphocyte reaction assay, the IC50 values for free CsA and CsA/PEG-PLGA-NPs were found to be 30 and 35 ng/mL, respectively. This nanoparticulate CsA delivery technology constitutes a strong basis for future targeted delivery of immunosuppressive drugs with improved efficiency and potentially reduced toxicity.