Examining the association between adult attachment style and cortisol responses to acute stress

PubMed Central

Kidd, Tara; Hamer, Mark; Steptoe, Andrew

2011-01-01

Summary The quality of social relationships may contribute to variations in biological stress responses, thereby affecting health risk. The association between an important indicator of social relationships, adult attachment style, and cortisol has been relatively unexplored. The present study examined adult romantic attachment style and cortisol responses to acute laboratory stress. Salivary cortisol was measured in response to two behavioural tasks, a colour/word interference task and mirror tracing task, in 498 healthy men and women from the Heart Scan study, a subsample of the Whitehall II cohort. Participants were classified as secure, fearful, preoccupied or dismissive on the basis of responses to the Relationship Questionnaire. Cortisol output was lowest in the fearful group, followed by the preoccupied group, with both secure and dismissive groups having higher levels. The results from this study tentatively support the proposition that attachment style is a factor in determining the manifestation of HPA dysregulation. PMID:21106296

Optics: Light, Color, and Their Uses. An Educator's Guide with Activities in Science and Mathematics.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

This educator's guide from discusses optics, light, color and their uses. Activities include: (1) "Reflection of Light with a Plane (Flat) Mirror--Trace a Star"; (2) "Reflection of Light with Two Plane Mirrors--Double Mirrors Placed at a 90-Degree Angle"; (3) "Reflection of Light with Two Plane Mirrors--Double Mirrors Placed at a Number of…

Point Relay Scanner Utilizing Ellipsoidal Mirrors

NASA Technical Reports Server (NTRS)

Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

1997-01-01

A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

Memory monitoring by animals and humans

NASA Technical Reports Server (NTRS)

Smith, J. D.; Shields, W. E.; Allendoerfer, K. R.; Washburn, D. A.; Rumbaugh, D. M. (Principal Investigator)

1998-01-01

The authors asked whether animals and humans would use similarly an uncertain response to escape indeterminate memories. Monkeys and humans performed serial probe recognition tasks that produced differential memory difficulty across serial positions (e.g., primacy and recency effects). Participants were given an escape option that let them avoid any trials they wished and receive a hint to the trial's answer. Across species, across tasks, and even across conspecifics with sharper or duller memories, monkeys and humans used the escape option selectively when more indeterminate memory traces were probed. Their pattern of escaping always mirrored the pattern of their primary memory performance across serial positions. Signal-detection analyses confirm the similarity of the animals' and humans' performances. Optimality analyses assess their efficiency. Several aspects of monkeys' performance suggest the cognitive sophistication of their decisions to escape.

TBA-like integral equations from quantized mirror curves

NASA Astrophysics Data System (ADS)

Okuyama, Kazumi; Zakany, Szabolcs

2016-03-01

Quantizing the mirror curve of certain toric Calabi-Yau (CY) three-folds leads to a family of trace class operators. The resolvent function of these operators is known to encode topological data of the CY. In this paper, we show that in certain cases, this resolvent function satisfies a system of non-linear integral equations whose structure is very similar to the Thermodynamic Bethe Ansatz (TBA) systems. This can be used to compute spectral traces, both exactly and as a semiclassical expansion. As a main example, we consider the system related to the quantized mirror curve of local P2. According to a recent proposal, the traces of this operator are determined by the refined BPS indices of the underlying CY. We use our non-linear integral equations to test that proposal.

Ray Tracing with Virtual Objects.

ERIC Educational Resources Information Center

Leinoff, Stuart

1991-01-01

Introduces the method of ray tracing to analyze the refraction or reflection of real or virtual images from multiple optical devices. Discusses ray-tracing techniques for locating images using convex and concave lenses or mirrors. (MDH)

Grazing Incidence Optics for X-rays Interferometry

NASA Technical Reports Server (NTRS)

Shipley, Ann; Zissa, David; Cash, Webster; Joy, Marshall

1999-01-01

Grazing incidence mirror parameters and constraints for x-ray interferometry are described. We present interferometer system tolerances and ray trace results used to define mirror surface accuracy requirements. Mirror material, surface figure, roughness, and geometry are evaluated based on analysis results. We also discuss mirror mount design constraints, finite element analysis, environmental issues, and solutions. Challenges associated with quantifying high accuracy mirror surface quality are addressed and test results are compared with theoretical predictions.

Mirror Observation of Finger Action Enhances Activity in Anterior Intraparietal Sulcus: A Functional Magnetic Resonance Imaging Study

PubMed Central

Murayama, Takashi; Takasugi, Jun; Monma, Masahiko; Oga, Masaru

2013-01-01

Mirror therapy can be used to promote recovery from paralysis in patients with post-stroke hemiplegia, There are a lot of reports that mirror-image observation of the unilateral moving hand enhanced the excitability of the primary motor area (M1) ipsilateral to the moving hand in healthy subjects. but the neural mechanisms underlying its therapeutic effects are currently unclear. To investigate this issue, we used functional magnetic resonance imaging to measure activity in brain regions related to visual information processing during mirror image movement observation. Thirteen healthy subjects performed a finger-thumb opposition task with the left and right hands separately, with or without access to mirror observation. In the mirror condition, one hand was reflected in a mirror placed above the abdomen in the MRI scanner. In the masked mirror condition, subjects performed the same task but with the mirror obscured. In both conditions, the other hand was held at rest behind the mirror. A between-task comparison (mirror versus masked mirror) revealed significant activation in the ipsilateral hemisphere in the anterior intraparietal sulcus (aIP) while performing all tasks, regardless of which hand was used. The right aIP was significantly activated while moving the right hand. In contrast, in the left aIP, a small number of voxels showed a tendency toward activation during both left and right hand movement. The enhancement of ipsilateral aIP activity by the mirror image observation of finger action suggests that bimodal aIP neurons can be activated by visual information. We propose that activation in the M1 ipsilateral to the moving hand can be induced by information passing through the ventral premotor area from the aIP. PMID:25792898

Minimizing Actuator-Induced Residual Error in Active Space Telescope Primary Mirrors

DTIC Science & Technology

2010-09-01

actuator geometry, and rib-to-facesheet intersection geometry are exploited to achieve improved performance in silicon carbide ( SiC ) mirrors . A...are exploited to achieve improved performance in silicon carbide ( SiC ) mirrors . A parametric finite element model is used to explore the trade space...MOST) finite element model. The move to lightweight actively-controlled silicon carbide ( SiC ) mirrors is traced back to previous generations of space

Cultural differences in self-recognition: the early development of autonomous and related selves?

PubMed

Ross, Josephine; Yilmaz, Mandy; Dale, Rachel; Cassidy, Rose; Yildirim, Iraz; Suzanne Zeedyk, M

2017-05-01

Fifteen- to 18-month-old infants from three nationalities were observed interacting with their mothers and during two self-recognition tasks. Scottish interactions were characterized by distal contact, Zambian interactions by proximal contact, and Turkish interactions by a mixture of contact strategies. These culturally distinct experiences may scaffold different perspectives on self. In support, Scottish infants performed best in a task requiring recognition of the self in an individualistic context (mirror self-recognition), whereas Zambian infants performed best in a task requiring recognition of the self in a less individualistic context (body-as-obstacle task). Turkish infants performed similarly to Zambian infants on the body-as-obstacle task, but outperformed Zambians on the mirror self-recognition task. Verbal contact (a distal strategy) was positively related to mirror self-recognition and negatively related to passing the body-as-obstacle task. Directive action and speech (proximal strategies) were negatively related to mirror self-recognition. Self-awareness performance was best predicted by cultural context; autonomous settings predicted success in mirror self-recognition, and related settings predicted success in the body-as-obstacle task. These novel data substantiate the idea that cultural factors may play a role in the early expression of self-awareness. More broadly, the results highlight the importance of moving beyond the mark test, and designing culturally sensitive tests of self-awareness. © 2016 John Wiley & Sons Ltd.

High-gamma activity in the human hippocampus and parahippocampus during inter-trial rest periods of a virtual navigation task.

PubMed

Pu, Yi; Cornwell, Brian R; Cheyne, Douglas; Johnson, Blake W

2018-05-19

In rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80-140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task. We found right hippocampal gamma oscillations mirrored the pattern of theta power in the same region during navigation, varying as a function of environmental novelty. Gamma power during inter-trial rest periods was positively correlated with theta power during navigation in the first task set when the environment was new and predicted greater performance improvement in the subsequent task set two where the environment became familiar. These findings provide evidence for human hippocampal reactivation accompanied by high-gamma activities immediately after learning and establish a link between hippocampal high-gamma activities and subsequent memory performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Influence of Procedural Learning on Iowa Gambling Task Performance Among HIV+ Individuals with History of Substance Dependence

PubMed Central

Gonzalez, Raul; Wardle, Margaret; Jacobus, Joanna; Vassileva, Jasmin; Martin-Thormeyer, Eileen M.

2010-01-01

HIV+ individuals have been shown to demonstrate deficits on the Iowa Gambling Task (IGT), a complex measure of “decision-making.” Little remains known about what other neurocognitive processes may account for variability in IGT performance among HIV+ samples or the role of procedural learning (PL) in IGT performance. A sample of 49 HIV+ individuals with a history of substance use disorders was examined to explore the relationship between IGT performance and three measures of PL: The Rotary Pursuit, Mirror Star Tracing, and Weather Prediction tasks. We found no statistically significant relationships between IGT performance and any of the PL tasks, despite finding significant correlations among the PL tasks. This pattern of results persisted when analyzing IGT performance in various ways (e.g., performance on earlier trial blocks or impairment classifications). Although other nondeclarative processes (e.g., somatic markers) may be important for IGT performance, these findings do not support PL as an important component neurocognitive process for the IGT. Similarly, these results suggest that differences in PL performance does not account for the decision-making deficits or variability in performances observed on the IGT among HIV+ individuals with a history of substance dependence. PMID:19939850

Ray-tracing of shape metrology data of grazing incidence x-ray astronomy mirrors

NASA Astrophysics Data System (ADS)

Zocchi, Fabio E.; Vernani, Dervis

2008-07-01

A number of future X-ray astronomy missions (e.g. Simbol-X, eROSITA) plan to utilize high throughput grazing incidence optics with very lightweight mirrors. The severe mass specifications require a further optimization of the existing technology with the consequent need of proper optical numerical modeling capabilities for both the masters and the mirrors. A ray tracing code has been developed for the simulation of the optical performance of type I Wolter masters and mirrors starting from 2D and 3D metrology data. In particular, in the case of 2D measurements, a 3D data set is reconstructed on the basis of dimensional references and used for the optical analysis by ray tracing. In this approach, the actual 3D shape is used for the optical analysis, thus avoiding the need of combining the separate contributions of different 2D measurements that require the knowledge of their interactions which is not normally available. The paper describes the proposed approach and presents examples of application on a prototype engineering master in the frame of ongoing activities carried out for present and future X-ray missions.

Design and mathematical analysis of a three-mirror X-ray telescope based on ATM S-056 X-ray telescope hardware

NASA Technical Reports Server (NTRS)

Foreman, J. W., Jr.; Cardone, J. M.

1973-01-01

The mathematical design of the aspheric third mirror for the three-mirror X-ray telescope (TMXRT) is presented, along with the imaging characteristics of the telescope obtained by a ray trace analysis. The present design effort has been directed entirely toward obtaining an aspheric third mirror which will be compatible with existing S-056 paraboloidal-hyperboloidal mirrors. This compatability will facilitate the construction of a prototype model of the TMXRT, since it will only be necessary to fabricate one new mirror in order to obtain a working model.

Efficacy of Mirror Therapy Containing Functional Tasks in Poststroke Patients

PubMed Central

2016-01-01

Objective To investigate the effect of mirror therapy containing functional tasks on upper extremity function and activities of daily living in patients with subacute stroke. Methods The subjects were randomly divided into two groups: the mirror therapy group (30 patients) and the sham therapy group (30 patients). The mirror therapy group underwent a mirror therapy program together with conventional therapy for 20 minutes per day on 5 days per week for 4 weeks. The control group received a sham conventional therapy program under the same schedule as the mirror therapy group. The Fugl-Meyer Motor Function Assessment (FMA), Brunnstrom motor recovery stage, and Modified Barthel Index (MBI) were evaluated 4 weeks after the treatment. Results The upper extremity function on the affected side and ability to perform daily life activities after the intervention were significantly improved in both groups. After 4 weeks of intervention, improvements in the FMA (p=0.027) and MBI (p=0.041) were significantly greater in the mirror therapy group than the sham therapy group. Conclusion In this study, we found that the mirror therapy containing functional task was effective in terms of improving the upper extremity functions and activities of daily living in patients with subacute stroke. PMID:27606269

Efficacy of Mirror Therapy Containing Functional Tasks in Poststroke Patients.

PubMed

Lim, Kil-Byung; Lee, Hong-Jae; Yoo, Jeehyun; Yun, Hyun-Ju; Hwang, Hye-Jung

2016-08-01

To investigate the effect of mirror therapy containing functional tasks on upper extremity function and activities of daily living in patients with subacute stroke. The subjects were randomly divided into two groups: the mirror therapy group (30 patients) and the sham therapy group (30 patients). The mirror therapy group underwent a mirror therapy program together with conventional therapy for 20 minutes per day on 5 days per week for 4 weeks. The control group received a sham conventional therapy program under the same schedule as the mirror therapy group. The Fugl-Meyer Motor Function Assessment (FMA), Brunnstrom motor recovery stage, and Modified Barthel Index (MBI) were evaluated 4 weeks after the treatment. The upper extremity function on the affected side and ability to perform daily life activities after the intervention were significantly improved in both groups. After 4 weeks of intervention, improvements in the FMA (p=0.027) and MBI (p=0.041) were significantly greater in the mirror therapy group than the sham therapy group. In this study, we found that the mirror therapy containing functional task was effective in terms of improving the upper extremity functions and activities of daily living in patients with subacute stroke.

Exploring the impact of visual and movement based priming on a motor intervention in the acute phase post-stroke in persons with severe hemiparesis of the upper extremity

PubMed Central

Patel, Jigna; Qiu, Qinyin; Yarossi, Mathew; Merians, Alma; Massood, Supriya; Tunik, Eugene; Adamovich, Sergei; Fluet, Gerard

2016-01-01

Purpose Explore the potential benefits of using priming methods prior to an active hand task in the acute phase post-stroke in persons with severe upper extremity hemiparesis. Methods Five individuals were trained using priming techniques including virtual reality (VR) based visual mirror feedback and contralaterally controlled passive movement strategies prior to training with an active pinch force modulation task. Clinical, kinetic, and neurophysiological measurements were taken pre and post the training period. Clinical measures were taken at six months post training. Results The two priming simulations and active training were well tolerated early after stroke. Priming effects were suggested by increased maximal pinch force immediately after visual and movement based priming. Despite having no clinically observable movement distally, the subjects were able to volitionally coordinate isometric force and muscle activity (EMG) in a pinch tracing task. The Root Mean Square Error (RMSE) of force during the pinch trace task gradually decreased over the training period suggesting learning may have occurred. Changes in motor cortical neurophysiology were seen in the unaffected hemisphere using Transcranial Magnetic Stimulation (TMS) mapping. Significant improvements in motor recovery as measured by the Action Research Arm Test (ARAT) and the Upper Extremity Fugl Meyer Assessment (UEFMA) were demonstrated at six months post training by three of the five subjects. Conclusion This study suggests that an early hand-based intervention using visual and movement based priming activities and a scaled motor task allows participation by persons without the motor control required for traditionally presented rehabilitation and testing. PMID:27636200

The effects of mirror therapy with tasks on upper extremity function and self-care in stroke patients.

PubMed

Park, Youngju; Chang, Moonyoung; Kim, Kyeong-Mi; An, Duk-Hyun

2015-05-01

[Purpose] The purpose of this study was to determine the effects of mirror therapy with tasks on upper extremity unction and self-care in stroke patients. [Subjects] Thirty participants were randomly assigned to either an experimental group (n=15) or a control group (n=15). [Methods] Subjects in the experimental group received mirror therapy with tasks, and those in the control group received a sham therapy; both therapies were administered, five times per week for six weeks. The main outcome measures were the Manual Function Test for the paralyzed upper limb and the Functional Independence Measure for self-care performance. [Results] The experimental group had more significant gains in change scores compared with the control group after the intervention. [Conclusion] We consider mirror therapy with tasks to be an effective form of intervention for upper extremity function and self-care in stroke patients.

Deficits in complex motor functions, despite no evidence of procedural learning deficits, among HIV+ individuals with history of substance dependence

PubMed Central

Gonzalez, Raul; Jacobus, Joanna; Amatya, Anup K.; Quartana, Phillip J.; Vassileva, Jasmin; Martin, Eileen M.

2008-01-01

HIV and drugs of abuse affect common neural systems underlying procedural memory, including the striatum. We compared performance of 48 HIV seropositive (HIV+) and 48 HIV seronegative (HIV−) participants with history of cocaine and/or heroin dependence across multiple Trial Blocks of three procedural learning (PL) tasks: Rotary Pursuit (RPT), Mirror Star Tracing (MST), and Weather Prediction (WPT). Groups were well matched on demographic, psychiatric, and substance use parameters, and all participants were verified abstinent from drugs. Mixed model ANOVAs revealed that the HIV+ group performed more poorly across all tasks, with a significant main effect of HIV serostatus observed on the MST and a trend toward significance obtained for the RPT. No significant differences were observed on the WPT. Both groups demonstrated significant improvements in performance across all three PL tasks. Importantly, no significant Serostatus X Trial Block interactions were observed on any task. Thus, the HIV+ group tended to perform worse than the HIV− group across all trial blocks of PL tasks with motor demands, but showed no differences in their rate of improvement across all tasks. These findings are consistent with HIV-associated deficits in complex motor skills, but not in procedural learning. PMID:18999351

Sleep benefits consolidation of visuo-motor adaptation learning in older adults.

PubMed

Mantua, Janna; Baran, Bengi; Spencer, Rebecca M C

2016-02-01

Sleep is beneficial for performance across a range of memory tasks in young adults, but whether memories are similarly consolidated in older adults is less clear. Performance benefits have been observed following sleep in older adults for declarative learning tasks, but this benefit may be reduced for non-declarative, motor skill learning tasks. To date, studies of sleep-dependent consolidation of motor learning in older adults are limited to motor sequence tasks. To examine whether reduced sleep-dependent consolidation in older adults is generalizable to other forms of motor skill learning, we examined performance changes over intervals of sleep and wake in young (n = 62) and older adults (n = 61) using a mirror-tracing task, which assesses visuo-motor adaptation learning. Participants learned the task either in the morning or in evening, and performance was assessed following a 12-h interval containing overnight sleep or daytime wake. Contrary to our prediction, both young adults and older adults exhibited sleep-dependent gains in visuo-motor adaptation. There was a correlation between performance improvement over sleep and percent of the night in non-REM stage 2 sleep. These results indicate that motor skill consolidation remains intact with increasing age although this relationship may be limited to specific forms of motor skill learning.

Hemispheric dominance during the mental rotation task in patients with schizophrenia.

PubMed

Chen, Jiu; Yang, Laiqi; Zhao, Jin; Li, Lanlan; Liu, Guangxiong; Ma, Wentao; Zhang, Yan; Wu, Xingqu; Deng, Zihe; Tuo, Ran

2012-04-01

Mental rotation is a spatial representation conversion capability using an imagined object and either object or self-rotation. This capability is impaired in schizophrenia. To provide a more detailed assessment of impaired cognitive functioning in schizophrenia by comparing the electrophysiological profiles of patients with schizophrenia and controls while completing a mental rotation task using both normally-oriented images and mirror images. This electroencephalographic study compared error rates, reaction times and the topographic map of event-related potentials in 32 participants with schizophrenia and 29 healthy controls during mental rotation tasks involving both normal images and mirror images. Among controls the mean error rate and the mean reaction time for normal images and mirror images were not significantly different but in the patient group the mean (sd) error rate was higher for mirror images than for normal images (42% [6%] vs. 32% [9%], t=2.64, p=0.031) and the mean reaction time was longer for mirror images than for normal images (587 [11] ms vs. 571 [18] ms, t=2.83, p=0.028). The amplitude of the P500 component at Pz (parietal area), Cz (central area), P3 (left parietal area) and P4 (right parietal area) were significantly lower in the patient group than in the control group for both normal images and mirror images. In both groups the P500 for both the normal and mirror images was significantly higher in the right parietal area (P4) compared with left parietal area (P3). The mental rotation abilities of patients with schizophrenia for both normally-oriented images and mirror images are impaired. Patients with schizophrenia show a diminished left cerebral contribution to the mental rotation task, a more rapid response time, and a differential response to normal images versus mirror images not seen in healthy controls. Specific topographic characteristics of the EEG during mental rotation tasks are potential biomarkers for schizophrenia.

Age difference in dual-task interference effects on procedural learning in children.

PubMed

Lejeune, Caroline; Desmottes, Lise; Catale, Corinne; Meulemans, Thierry

2015-01-01

The current study aimed to investigate the role played by explicit mechanisms during procedural learning in two age groups of children (7 and 10 years) using a dual-task paradigm. To do this, we explored the effect of an interference task during the early and late phases of a mirror tracing learning task. The results showed a differential impact of the secondary task on the two age groups, but only during the first learning phase; the performance of 10-year-olds was affected by the second task, whereas in 7-year-olds no performance difference was found between the single- and dual-task conditions. Overall, our study suggests that there are differences in the amount of effortful processing in which 7- and 10-year-olds engage at the beginning of the learning process; procedural learning in young children is mainly implicit, as attested by its lesser sensitivity to an interference task, whereas high-level explicit mechanisms seem to contribute to the procedural performance of 10-year-olds. However, these explicit mechanisms, even if they have an effect on performance, might not have an impact on the learning curve given that no difference in rate of acquisition was found between age groups. These findings are discussed in the light of classical conceptions of procedural learning. Copyright © 2014 Elsevier Inc. All rights reserved.

Virtual Ray Tracing as a Conceptual Tool for Image Formation in Mirrors and Lenses

ERIC Educational Resources Information Center

Heikkinen, Lasse; Savinainen, Antti; Saarelainen, Markku

2016-01-01

The ray tracing method is widely used in teaching geometrical optics at the upper secondary and university levels. However, using simple and straightforward examples may lead to a situation in which students use the model of ray tracing too narrowly. Previous studies show that students seem to use the ray tracing method too concretely instead of…

Motion of the drawing hand induces a progressive increase in muscle activity of the non-dominant hand in Ramachandran's mirror-box therapy.

PubMed

Furukawa, Kiminobu; Suzuki, Harue; Fukuda, Jun

2012-11-01

To observe the real-time muscle activity of bilateral hands while subjects draw circles under 2 conditions: with and without using Ramachandran's mirror-box. A total of 24 healthy volunteers. Subjects drew 4 circles sequentially using their dominant hand with the other hand at rest, both with and without looking at a mirror image. Circles were marked by 8 dots on the paper, which subjects connected up to draw the shape. The activity of the bilateral first dorsal interosseus muscles was recorded using surface electromyography. Muscle activity of the dominant hand remained constant during each task. In contrast, muscle activity of the non-dominant hand increased under the condition of watching the image in the mirror, but was low under the non-watching condition. Furthermore, muscle activity of the non-dominant hand increased over the duration of the task. However, wide variation between subjects was observed under the mirror-image condition. Increased muscle action potential of the non-dominant hand may be induced by the circle drawing task of the dominant hand during Ramachandran's mirror-box therapy, which supports previous observations of increased brain activity caused by watching a mirror image.

Imitation and action understanding in autistic spectrum disorders: how valid is the hypothesis of a deficit in the mirror neuron system?

PubMed

Hamilton, Antonia F de C; Brindley, Rachel M; Frith, Uta

2007-04-09

The motor mirror neuron system supports imitation and goal understanding in typical adults. Recently, it has been proposed that a deficit in this mirror neuron system might contribute to poor imitation performance in children with autistic spectrum disorders (ASD) and might be a cause of poor social abilities in these children. We aimed to test this hypothesis by examining the performance of 25 children with ASD and 31 typical children of the same verbal mental age on four action representation tasks and a theory of mind battery. Both typical and autistic children had the same tendency to imitate an adult's goals, to imitate in a mirror fashion and to imitate grasps in a motor planning task. Children with ASD showed superior performance on a gesture recognition task. These imitation and gesture recognition tasks all rely on the mirror neuron system in typical adults, but performance was not impaired in children with ASD. In contrast, the ASD group were impaired on the theory of mind tasks. These results provide clear evidence against a general imitation impairment and a global mirror neuron system deficit in children with autism. We suggest this data can best be understood in terms of multiple brain systems for different types of imitation and action understanding, and that the ability to understand and imitate the goals of hand actions is intact in children with ASD.

Successful Graded Mirror Therapy in a Patient with Chronic Deafferentation Pain in Whom Traditional Mirror Therapy was Ineffective: A Case Report.

PubMed

Mibu, Akira; Nishigami, Tomohiko; Tanaka, Katsuyoshi; Osumi, Michihiro; Tanabe, Akihito

2016-04-01

A 43-year-old man had deafferentation pain in his right upper extremity secondary to brachial plexus avulsion from a traffic accident 23 years previously. On our initial examination, he had severe tingling pain with numbness in the right fingers rated 10 on the numerical rating scale. The body perception of the affected third and fourth fingers was distorted in the flexed position. Although he performed traditional mirror therapy (TMT) for 4 weeks in the same methods as seen in previous studies, he could not obtain willed motor imagery and pain-alleviation effect. Therefore, we modified the task of TMT: Graded mirror therapy (GMT). GMT consisted of five stages: (1) observation of the mirror reflection of the unaffected side without imagining any movements of the affected side; (2) observation of the mirror reflection of the third and fourth fingers changing shape gradually adjusted from a flexed position to a extended position; (3) observation of the mirror reflection of passive movement; (4) motor imagery of affected fingers with observation of the mirror reflection (similar to TMT); (5) motor imagery of affected fingers without mirror. Each task was performed for 3 to 4 weeks. As a result, pain intensity during mirror therapy gradually decreased and finally disappeared. The body perception of the affected fingers also improved, and he could imagine the movement of the fingers with or without mirror. We suggested that GMT starting from the observation task without motor imagery may effectively decrease deafferentation pain compared to TMT. © 2016 World Institute of Pain.

Distress tolerance: Associations with trauma and substance cue reactivity in low-income, inner-city adults with substance use disorders and posttraumatic stress.

PubMed

Vujanovic, Anka A; Wardle, Margaret C; Bakhshaie, Jafar; Smith, Lia J; Green, Charles E; Lane, Scott D; Schmitz, Joy M

2018-05-01

Cue reactivity has great potential to advance our understanding of posttraumatic stress disorder (PTSD), substance use disorder (SUD), and PTSD/SUD comorbidity. The present investigation examined distress tolerance (DT) with regard to trauma and substance cue reactivity. Participants included 58 low-income, inner-city adults (49.1% women; M age = 45.73, SD = 10.00) with substance dependence and at least 4 symptoms of PTSD. A script-driven cue reactivity paradigm was utilized. Four DT measures were administered, including the Distress Tolerance Scale (DTS), Mirror-Tracing Persistence Task (MTPT), Breath-Holding Task (BH), and Paced Auditory Serial Addition Task (PASAT). Lower DT, as indexed by MTPT duration, was significantly predictive of greater levels of self-reported substance cravings/urges in response to trauma cues, above and beyond covariates. Lower DTS scores predicted lower levels of self-reported control/safety ratings in response to substance cues. None of the DT indices was significantly predictive of heart rate variability. Clinical and research implications are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Solar Thermal Propulsion for Microsatellite Manoeuvring

DTIC Science & Technology

2004-09-01

of 14-cm and 56-cm diameter solar concentrating mirrors has clearly validated initial optical ray trace modelling and suggests that there is...concentrating mirror’s focus, permitting multiple mirror inputs to heat a single receiver and allowing the receiver to be placed anywhere on the host...The STE is conceptually simple, relying on a mirror or lens assembly to collect and concentrate incident solar radiation. This energy is focused, by

Depth rotation and mirror-image reflection reduce affective preference as well as recognition memory for pictures of novel objects.

PubMed

Lawson, Rebecca

2004-10-01

In two experiments, the identification of novel 3-D objects was worse for depth-rotated and mirror-reflected views, compared with the study view in an implicit affective preference memory task, as well as in an explicit recognition memory task. In Experiment 1, recognition was worse and preference was lower when depth-rotated views of an object were paired with an unstudied object relative to trials when the study view of that object was shown. There was a similar trend for mirror-reflected views. In Experiment 2, the study view of an object was both recognized and preferred above chance when it was paired with either depth-rotated or mirror-reflected views of that object. These results suggest that view-sensitive representations of objects mediate performance in implicit, as well as explicit, memory tasks. The findings do not support the claim that separate episodic and structural description representations underlie performance in implicit and explicit memory tasks, respectively.

Mirror Therapy and Task-Oriented Training for People With a Paretic Upper Extremity.

PubMed

Bondoc, Salvador; Booth, Julie; Budde, Grace; Caruso, Katelyn; DeSousa, Michelle; Earl, Brittany; Hammerton, Kaitlynn; Humphreys, Jill

This study investigates the effect of mirror therapy and task-oriented training on the paretic upper extremity function and occupational performance of people with stroke. This study used a repeated-measures, case-series design in which 4 participants completed a 4-wk intervention consisting of mirror therapy and task-specific training. The intervention was conducted 2×/wk in the clinic and 4×/wk at home. All participants displayed clinically meaningful improvements in self-identified goals at the end of the intervention and at follow-up. Three participants showed clinically meaningful changes in motor function. Although only 1 participant improved in his reported amount of use, all participants showed clinically meaningful improvements in perceived movement quality at varying points of assessment. Mirror therapy, when used as priming for task-oriented training, can produce clinical improvements in upper extremity function and occupational performance in people with hemiparesis. Copyright © 2018 by the American Occupational Therapy Association, Inc.

Elimination of 'ghost'-effect-related systematic error in metrology of X-ray optics with a long trace profiler

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

Yashchuk, Valeriy V.; Irick, Steve C.; MacDowell, Alastair A.

2005-04-28

A data acquisition technique and relevant program for suppression of one of the systematic effects, namely the ''ghost'' effect, of a second generation long trace profiler (LTP) is described. The ''ghost'' effect arises when there is an unavoidable cross-contamination of the LTP sample and reference signals into one another, leading to a systematic perturbation in the recorded interference patterns and, therefore, a systematic variation of the measured slope trace. Perturbations of about 1-2 {micro}rad have been observed with a cylindrically shaped X-ray mirror. Even stronger ''ghost'' effects show up in an LTP measurement with a mirror having a toroidal surfacemore » figure. The developed technique employs separate measurement of the ''ghost''-effect-related interference patterns in the sample and the reference arms and then subtraction of the ''ghost'' patterns from the sample and the reference interference patterns. The procedure preserves the advantage of simultaneously measuring the sample and reference signals. The effectiveness of the technique is illustrated with LTP metrology of a variety of X-ray mirrors.« less

Challenging Cognitive Control by Mirrored Stimuli in Working Memory Matching

PubMed Central

Wirth, Maria; Gaschler, Robert

2017-01-01

Cognitive conflict has often been investigated by placing automatic processing originating from learned associations in competition with instructed task demands. Here we explore whether mirror generalization as a congenital mechanism can be employed to create cognitive conflict. Past research suggests that the visual system automatically generates an invariant representation of visual objects and their mirrored counterparts (i.e., mirror generalization), and especially so for lateral reversals (e.g., a cup seen from the left side vs. right side). Prior work suggests that mirror generalization can be reduced or even overcome by learning (i.e., for those visual objects for which it is not appropriate, such as letters d and b). We, therefore, minimized prior practice on resolving conflicts involving mirror generalization by using kanji stimuli as non-verbal and unfamiliar material. In a 1-back task, participants had to check a stream of kanji stimuli for identical repetitions and avoid miss-categorizing mirror reversed stimuli as exact repetitions. Consistent with previous work, lateral reversals led to profound slowing of reaction times and lower accuracy in Experiment 1. Yet, different from previous reports suggesting that lateral reversals lead to stronger conflict, similar slowing for vertical and horizontal mirror transformations was observed in Experiment 2. Taken together, the results suggest that transformations of visual stimuli can be employed to challenge cognitive control in the 1-back task. PMID:28503160

Network activity of mirror neurons depends on experience.

PubMed

Ushakov, Vadim L; Kartashov, Sergey I; Zavyalova, Victoria V; Bezverhiy, Denis D; Posichanyuk, Vladimir I; Terentev, Vasliliy N; Anokhin, Konstantin V

2013-03-01

In this work, the investigation of network activity of mirror neurons systems in animal brains depending on experience (existence or absence performance of the shown actions) was carried out. It carried out the research of mirror neurons network in the C57/BL6 line mice in the supervision task of swimming mice-demonstrators in Morris water maze. It showed the presence of mirror neurons systems in the motor cortex M1, M2, cingular cortex, hippocampus in mice groups, having experience of the swimming and without it. The conclusion is drawn about the possibility of the new functional network systems formation by means of mirror neurons systems and the acquisition of new knowledge through supervision by the animals in non-specific tasks.

A complete ray-trace analysis of the Mirage toy

NASA Astrophysics Data System (ADS)

Adhya, Sriya; Noé, John W.

2007-06-01

The `Mirage' (Opti-Gone International) is a well-known optics demonstration (PIRA index number 6A20.35) that uses two opposed concave mirrors to project a real image of a small object into space. We studied image formation in the Mirage by standard 2x2 matrix methods and by exact ray tracing, with particular attention to additional real images that can be observed when the mirror separation is increased beyond one focal length. We find that the three readily observed secondary images correspond to 4, 6, or 8 reflections, respectively, contrary to previous reports.

Interrelating Behavioral Measures of Distress Tolerance with Self-Reported Experiential Avoidance.

PubMed

Schloss, Heather M; Haaga, David A F

2011-03-01

Experiential avoidance and distress intolerance play a central role in novel behavior therapies, yet they appear to overlap considerably the REBT concept of low frustration tolerance. Using baseline data from 100 adult cigarette smokers enrolled in a clinical trial of smoking cessation therapies, the present study evaluated the convergent validity of common questionnaire measures of experiential avoidance (Acceptance and Action Questionnaire; AAQ; Hayes et al. 2004, and Avoidance and Inflexibility Scale: AIS; Gifford et al. 2004) and behavioral measures of distress tolerance (computerized Mirror Tracing Persistence Task: MTPT-C: Strong et al. 2003; computerized Paced Auditory Serial Addition Task; PASAT-C; Lejuez et al. 2003). The distress tolerance measures correlated significantly (r = .29) with one another. However, the questionnaire measures of experiential avoidance did not correlate with each other, nor with the behavioral measures. Further research is needed on the validity of measuring experiential avoidance by self-report and of the overlap versus distinctiveness of seemingly similar constructs such as experiential avoidance, distress tolerance, and frustration tolerance.

Interrelating Behavioral Measures of Distress Tolerance with Self-Reported Experiential Avoidance

PubMed Central

Schloss, Heather M.

2011-01-01

Experiential avoidance and distress intolerance play a central role in novel behavior therapies, yet they appear to overlap considerably the REBT concept of low frustration tolerance. Using baseline data from 100 adult cigarette smokers enrolled in a clinical trial of smoking cessation therapies, the present study evaluated the convergent validity of common questionnaire measures of experiential avoidance (Acceptance and Action Questionnaire; AAQ; Hayes et al. 2004, and Avoidance and Inflexibility Scale: AIS; Gifford et al. 2004) and behavioral measures of distress tolerance (computerized Mirror Tracing Persistence Task: MTPT-C: Strong et al. 2003; computerized Paced Auditory Serial Addition Task; PASAT-C; Lejuez et al. 2003). The distress tolerance measures correlated significantly (r = .29) with one another. However, the questionnaire measures of experiential avoidance did not correlate with each other, nor with the behavioral measures. Further research is needed on the validity of measuring experiential avoidance by self-report and of the overlap versus distinctiveness of seemingly similar constructs such as experiential avoidance, distress tolerance, and frustration tolerance. PMID:21448252

The neuronal correlates of mirror therapy: A functional magnetic resonance imaging study on mirror-induced visual illusions of ankle movements.

PubMed

Guo, Feng; Xu, Qun; Abo Salem, Hassan M; Yao, Yihao; Lou, Jicheng; Huang, Xiaolin

2016-05-15

Recovery in stroke is mediated by neural plasticity. Mirror therapy is an effective method in the rehabilitation of stroke patients, but the mechanism is still obscure. To identify the neural networks associated with the effect of lower-limbs mirror therapy, we investigated a functional magnetic resonance imaging (fMRI) study of mirror-induced visual illusion of ankle movements. Five healthy controls and five left hemiplegic stroke patients performed tasks related to mirror therapy in the fMRI study. Neural activation was compared in a no-mirror condition and a mirror condition. All subjects in the experiment performed the task of flexing and extending the right ankle. In a mirror condition, movement of the left ankle was simulated by mirror reflection of right ankle movement. Changes in neural activation in response to mirror therapy were assessed both in healthy controls and stroke patients. We found strong activation of the motor cortex bilaterally in healthy controls, as well as significant activation of the ipsilateral sensorimotor cortex, the occipital gyrus, and the anterior prefrontal gyrus in stroke patients with respect to the non-mirror condition. We concluded that mirror therapy of ankle movements may induce neural activation of the ipsilesional sensorimotor cortex, and that cortical reorganization may be useful for motor rehabilitation in stroke. Copyright © 2016 Elsevier B.V. All rights reserved.

Impaired white matter connectivity between regions containing mirror neurons, and relationship to negative symptoms and social cognition, in patients with first-episode schizophrenia.

PubMed

Saito, Yukiko; Kubicki, Marek; Koerte, Inga; Otsuka, Tatsui; Rathi, Yogesh; Pasternak, Ofer; Bouix, Sylvain; Eckbo, Ryan; Kikinis, Zora; von Hohenberg, Christian Clemm; Roppongi, Tomohide; Del Re, Elisabetta; Asami, Takeshi; Lee, Sang-Hyuk; Karmacharya, Sarina; Mesholam-Gately, Raquelle I; Seidman, Larry J; Levitt, James; McCarley, Robert W; Shenton, Martha E; Niznikiewicz, Margaret A

2018-02-01

In schizophrenia, abnormalities in structural connectivity between brain regions known to contain mirror neurons and their relationship to negative symptoms related to a domain of social cognition are not well understood. Diffusion tensor imaging (DTI) scans were acquired in 16 patients with first episode schizophrenia and 16 matched healthy controls. FA and Trace of the tracts interconnecting regions known to be rich in mirror neurons, i.e., anterior cingulate cortex (ACC), inferior parietal lobe (IPL) and premotor cortex (PMC) were evaluated. A significant group effect for Trace was observed in IPL-PMC white matter fiber tract (F (1, 28) = 7.13, p = .012), as well as in the PMC-ACC white matter fiber tract (F (1, 28) = 4.64, p = .040). There were no group differences in FA. In addition, patients with schizophrenia showed a significant positive correlation between the Trace of the left IPL-PMC white matter fiber tract, and the Ability to Feel Intimacy and Closeness score (rho = .57, p = 0.034), and a negative correlation between the Trace of the left PMC-ACC and the Relationships with Friends and Peers score (rho = remove -.54, p = 0.049). We have demonstrated disrupted white mater microstructure within the white matter tracts subserving brain regions containing mirror neurons. We further showed that such structural disruptions might impact negative symptoms and, more specifically, contribute to the inability to feel intimacy (a measure conceptually related to theory of mind) in first episode schizophrenia. Further studies are needed to understand the potential of our results for diagnosis, prognosis and therapeutic interventions.

Effects of Small Oscillations on the Effective Area

NASA Astrophysics Data System (ADS)

Cotroneo, V.; Conconi, P.; Cusumano, G.; Pareschi, G.; Spiga, D.; Tagliaferri, G.

2009-05-01

We analyze the effective area of the Simbol-X mirrors as a function of the off-axis angle for small oscillations. A reduction is expected due to: 1) geometrical effects, because some of the photons miss the secondary mirror surface; 2) reflectivity effects, caused by the variation of the coating reflectivity with the incidence angle. The former are related to the length of the two mirror surfaces, and can be reduced by making the secondary mirror longer. The second ones are energy-dependent, and strongly related to the characteristics of the reflecting coating. These effects are analyzed by means of ray-tracing simulations in order to optimize the mirror and coating design, aiming to improve the effective area stability.

Reverse alignment "mirror image" visualization as a laparoscopic training tool improves task performance.

PubMed

Dunnican, Ward J; Singh, T Paul; Ata, Ashar; Bendana, Emma E; Conlee, Thomas D; Dolce, Charles J; Ramakrishnan, Rakesh

2010-06-01

Reverse alignment (mirror image) visualization is a disconcerting situation occasionally faced during laparoscopic operations. This occurs when the camera faces back at the surgeon in the opposite direction from which the surgeon's body and instruments are facing. Most surgeons will attempt to optimize trocar and camera placement to avoid this situation. The authors' objective was to determine whether the intentional use of reverse alignment visualization during laparoscopic training would improve performance. A standard box trainer was configured for reverse alignment, and 34 medical students and junior surgical residents were randomized to train with either forward alignment (DIRECT) or reverse alignment (MIRROR) visualization. Enrollees were tested on both modalities before and after a 4-week structured training program specific to their modality. Student's t test was used to determine differences in task performance between the 2 groups. Twenty-one participants completed the study (10 DIRECT, 11 MIRROR). There were no significant differences in performance time between DIRECT or MIRROR participants during forward or reverse alignment initial testing. At final testing, DIRECT participants had improved times only in forward alignment performance; they demonstrated no significant improvement in reverse alignment performance. MIRROR participants had significant time improvement in both forward and reverse alignment performance at final testing. Reverse alignment imaging for laparoscopic training improves task performance for both reverse alignment and forward alignment tasks. This may be translated into improved performance in the operating room when faced with reverse alignment situations. Minimal lab training can account for drastic adaptation to this environment.

Age-Specific Effects of Mirror-Muscle Activity on Cross-Limb Adaptations Under Mirror and Non-Mirror Visual Feedback Conditions.

PubMed

Reissig, Paola; Stöckel, Tino; Garry, Michael I; Summers, Jeffery J; Hinder, Mark R

2015-01-01

Cross-limb transfer (CLT) describes the observation of bilateral performance gains due to unilateral motor practice. Previous research has suggested that CLT may be reduced, or absent, in older adults, possibly due to age-related structural and functional brain changes. Based on research showing increases in CLT due to the provision of mirror visual feedback (MVF) during task execution in young adults, our study aimed to investigate whether MVF can facilitate CLT in older adults, who are known to be more reliant on visual feedback for accurate motor performance. Participants (N = 53) engaged in a short-term training regime (300 movements) involving a ballistic finger task using their dominant hand, while being provided with either visual feedback of their active limb, or a mirror reflection of their active limb (superimposed over the quiescent limb). Performance in both limbs was examined before, during and following the unilateral training. Furthermore, we measured corticospinal excitability (using TMS) at these time points, and assessed muscle activity bilaterally during the task via EMG; these parameters were used to investigate the mechanisms mediating and predicting CLT. Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1). Training also elicited bilateral increases in corticospinal excitability (p < 0.05). For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60). The present study suggests that older adults are capable of exhibiting CLT to a similar degree to younger adults. The prominent role of mirror activity in the untrained hand for CLT in older adults indicates that bilateral cortical activity during unilateral motor tasks is a compensatory mechanism. In this particular task, MVF did not facilitate the extent of CLT.

Photorealistic ray tracing to visualize automobile side mirror reflective scenes.

PubMed

Lee, Hocheol; Kim, Kyuman; Lee, Gang; Lee, Sungkoo; Kim, Jingu

2014-10-20

We describe an interactive visualization procedure for determining the optimal surface of a special automobile side mirror, thereby removing the blind spot, without the need for feedback from the error-prone manufacturing process. If the horizontally progressive curvature distributions are set to the semi-mathematical expression for a free-form surface, the surface point set can then be derived through numerical integration. This is then converted to a NURBS surface while retaining the surface curvature. Then, reflective scenes from the driving environment can be virtually realized using photorealistic ray tracing, in order to evaluate how these reflected images would appear to drivers.

Image analysis of the AXAF VETA-I x ray mirror

NASA Technical Reports Server (NTRS)

Freeman, Mark D.; Hughes, John P; Vanspeybroeck, L.; Weisskopf, M.; Bilbro, J.

1992-01-01

Initial core scan data of the VETA-I x-ray mirror proved disappointing, showing considerable unpredicted image structure and poor measured FWHM. 2-D core scans were performed, providing important insight into the nature of the distortion. Image deconvolutions using a ray traced model PSF was performed successfully to reinforce our conclusion regarding the origin of the astigmatism. A mechanical correction was made to the optical structure, and the mirror was tested successfully (FWHM 0.22 arcsec) as a result.

Haptic spatial matching in near peripersonal space.

PubMed

Kaas, Amanda L; Mier, Hanneke I van

2006-04-01

Research has shown that haptic spatial matching at intermanual distances over 60 cm is prone to large systematic errors. The error pattern has been explained by the use of reference frames intermediate between egocentric and allocentric coding. This study investigated haptic performance in near peripersonal space, i.e. at intermanual distances of 60 cm and less. Twelve blindfolded participants (six males and six females) were presented with two turn bars at equal distances from the midsagittal plane, 30 or 60 cm apart. Different orientations (vertical/horizontal or oblique) of the left bar had to be matched by adjusting the right bar to either a mirror symmetric (/ \\) or parallel (/ /) position. The mirror symmetry task can in principle be performed accurately in both an egocentric and an allocentric reference frame, whereas the parallel task requires an allocentric representation. Results showed that parallel matching induced large systematic errors which increased with distance. Overall error was significantly smaller in the mirror task. The task difference also held for the vertical orientation at 60 cm distance, even though this orientation required the same response in both tasks, showing a marked effect of task instruction. In addition, men outperformed women on the parallel task. Finally, contrary to our expectations, systematic errors were found in the mirror task, predominantly at 30 cm distance. Based on these findings, we suggest that haptic performance in near peripersonal space might be dominated by different mechanisms than those which come into play at distances over 60 cm. Moreover, our results indicate that both inter-individual differences and task demands affect task performance in haptic spatial matching. Therefore, we conclude that the study of haptic spatial matching in near peripersonal space might reveal important additional constraints for the specification of adequate models of haptic spatial performance.

The Development of Mirror Self-Recognition in Different Sociocultural Contexts

ERIC Educational Resources Information Center

Kartner, Joscha; Keller, Heidi; Chaudhary, Nandita; Yovsi, Relindis D.

2012-01-01

The overarching goal of the present study was to trace the development of mirror self-recognition (MSR), as an index of toddlers' sense of themselves and others as autonomous intentional agents, in different sociocultural environments. A total of 276 toddlers participated in the present study. Toddlers were either 16, 17, 18, 19, 20, or 21 months…

Comparison of elliptical and spherical mirrors for the grasshopper monochromators at SSRL

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

Waldhauer, A. P.

1989-07-01

A comparison of the performance of a spherical and elliptical mirror in the grasshopper monochromator is presented. The problem was studied by ray tracing and then tested using visible (/lambda/=633 nm) laser light. Calculations using ideal optics yield an improvement in flux by a factor of up to 2.7, while tests with visible light show an increase by a factor of 5 because the old spherical mirror is compared to a new, perfect elliptical one. The FWHM of the measured focus is 90 /mu/m with a spherical mirror, and 25 /mu/m with an elliptical one. Elliptical mirrors have been acquiredmore » and are now being installed in the two grasshoppers at SSRL.« less

Improved Mirror Source Method in Roomacoustics

NASA Astrophysics Data System (ADS)

Mechel, F. P.

2002-10-01

Most authors in room acoustics qualify the mirror source method (MS-method) as the only exact method to evaluate sound fields in auditoria. But evidently nobody applies it. The reason for this discrepancy is the abundantly high numbers of needed mirror sources which are reported in the literature, although such estimations of needed numbers of mirror sources mostly are used for the justification of more or less heuristic modifications of the MS-method. The present, intentionally tutorial article accentuates the analytical foundations of the MS-method whereby the number of needed mirror sources is reduced already. Further, the task of field evaluation in three-dimensional spaces is reduced to a sequence of tasks in two-dimensional room edges. This not only allows the use of easier geometrical computations in two dimensions, but also the sound field in corner areas can be represented by a single (directional) source sitting on the corner line, so that only this "corner source" must be mirror-reflected in the further process. This procedure gives a drastic reduction of the number of needed equivalent sources. Finally, the traditional MS-method is not applicable in rooms with convex corners (the angle between the corner flanks, measured on the room side, exceeds 180°). In such cases, the MS-method is combined below with the second principle of superposition(PSP). It reduces the scattering task at convex corners to two sub-tasks between one flank and the median plane of the room wedge, i.e., always in concave corner areas where the MS-method can be applied.

Ray-trace analysis of glancing-incidence X-ray optical systems

NASA Technical Reports Server (NTRS)

Foreman, J. W., Jr.; Cardone, J. M.

1976-01-01

The results of a ray-trace analysis of several glancing-incidence X-ray optical systems are presented. The object of the study was threefold. First, the vignetting characteristics of the S-056 X-ray telescope were calculated using experimental data to determine mirror reflectivities. Second, a small Wolter Type I X-ray telescope intended for possible use in the Geostationary Operational Environmental Satellite program was designed and ray traced. Finally, a ray-trace program was developed for a Wolter-Schwarzschild X-ray telescope.

Integrated optical design for highly dynamic laser beam shaping with membrane deformable mirrors

NASA Astrophysics Data System (ADS)

Pütsch, Oliver; Stollenwerk, Jochen; Loosen, Peter

2017-02-01

The utilization of membrane deformable mirrors has raised its importance in laser materials processing since they enable the generation of highly spatial and temporal dynamic intensity distributions for a wide field of applications. To take full advantage of these devices for beam shaping, the huge amount of degrees of freedom has to be considered and optimized already within the early stage of the optical design. Since the functionality of commercial available ray-tracing software has been mainly specialized on geometric dependencies and their optimization within constraints, the complex system characteristics of deformable mirrors cannot be sufficiently taken into account yet. The main reasons are the electromechanical interdependencies of electrostatic membrane deformable mirrors, namely saturation and mechanical clamping, that result in non-linear deformation. This motivates the development of an integrative design methodology. The functionality of the ray-tracing program ZEMAX is extended with a model of an electrostatic membrane mirror. This model is based on experimentally determined influence functions. Furthermore, software routines are derived and integrated that allow for the compilation of optimization criteria for the most relevant analytically describable beam shaping problems. In this way, internal optimization routines can be applied for computing the appropriate membrane deflection of the deformable mirror as well as for the parametrization of static optical components. The experimental verification of simulated intensity distributions demonstrates that the beam shaping properties can be predicted with a high degree of reliability and precision.

Eliminating mirror responses by instructions.

PubMed

Bardi, Lara; Bundt, Carsten; Notebaert, Wim; Brass, Marcel

2015-09-01

The observation of an action leads to the activation of the corresponding motor plan in the observer. This phenomenon of motor resonance has an important role in social interaction, promoting imitation, learning and action understanding. However, mirror responses not always have a positive impact on our behavior. An automatic tendency to imitate others can introduce interference in action execution and non-imitative or opposite responses have an advantage in some contexts. Previous studies suggest that mirror tendencies can be suppressed after extensive practice or in complementary joint action situations revealing that mirror responses are more flexible than previously thought. The aim of the present study was to gain insight into the mechanisms that allow response flexibility of motor mirroring. Here we show that the mere instruction of a counter-imitative mapping changes mirror responses as indexed by motor evoked potentials (MEPs) enhancement induced by transcranial magnetic stimulation (TMS). Importantly, mirror activation was measured while participants were passively watching finger movements, without having the opportunity to execute the task. This result suggests that the implementation of task instructions activates stimulus-response association that can overwrite the mirror representations. Our outcome reveals one of the crucial mechanisms that might allow flexible adjustments of mirror responses in different contexts. The implications of this outcome are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mirror Visual Feedback Training Improves Intermanual Transfer in a Sport-Specific Task: A Comparison between Different Skill Levels.

PubMed

Steinberg, Fabian; Pixa, Nils Henrik; Doppelmayr, Michael

2016-01-01

Mirror training therapy is a promising tool to initiate neural plasticity and facilitate the recovery process of motor skills after diseases such as stroke or hemiparesis by improving the intermanual transfer of fine motor skills in healthy people as well as in patients. This study evaluated whether these augmented performance improvements by mirror visual feedback (MVF) could be used for learning a sport-specific skill and if the effects are modulated by skill level. A sample of 39 young, healthy, and experienced basketball and handball players and 41 novices performed a stationary basketball dribble task at a mirror box in a standing position and received either MVF or direct feedback. After four training days using only the right hand, performance of both hands improved from pre- to posttest measurements. Only the left hand (untrained) performance of the experienced participants receiving MVF was more pronounced than for the control group. This indicates that intermanual motor transfer can be improved by MVF in a sport-specific task. However, this effect cannot be generalized to motor learning per se since it is modulated by individuals' skill level, a factor that might be considered in mirror therapy research.

Mirror Visual Feedback Training Improves Intermanual Transfer in a Sport-Specific Task: A Comparison between Different Skill Levels

PubMed Central

Pixa, Nils Henrik; Doppelmayr, Michael

2016-01-01

Mirror training therapy is a promising tool to initiate neural plasticity and facilitate the recovery process of motor skills after diseases such as stroke or hemiparesis by improving the intermanual transfer of fine motor skills in healthy people as well as in patients. This study evaluated whether these augmented performance improvements by mirror visual feedback (MVF) could be used for learning a sport-specific skill and if the effects are modulated by skill level. A sample of 39 young, healthy, and experienced basketball and handball players and 41 novices performed a stationary basketball dribble task at a mirror box in a standing position and received either MVF or direct feedback. After four training days using only the right hand, performance of both hands improved from pre- to posttest measurements. Only the left hand (untrained) performance of the experienced participants receiving MVF was more pronounced than for the control group. This indicates that intermanual motor transfer can be improved by MVF in a sport-specific task. However, this effect cannot be generalized to motor learning per se since it is modulated by individuals' skill level, a factor that might be considered in mirror therapy research. PMID:27642526

Upper extremity rehabilitation of stroke: facilitation of corticospinal excitability using virtual mirror paradigm.

PubMed

Kang, Youn Joo; Park, Hae Kyung; Kim, Hyun Jung; Lim, Taeo; Ku, Jeonghun; Cho, Sangwoo; Kim, Sun I; Park, Eun Sook

2012-10-04

Several experimental studies in stroke patients suggest that mirror therapy and various virtual reality programs facilitate motor rehabilitation. However, the underlying mechanisms for these therapeutic effects have not been previously described. We attempted to delineate the changes in corticospinal excitability when individuals were asked to exercise their upper extremity using a real mirror and virtual mirror. Moreover, we attempted to delineate the role of visual modulation within the virtual environment that affected corticospinal excitability in healthy subjects and stroke patients. A total of 18 healthy subjects and 18 hemiplegic patients were enrolled into the study. Motor evoked potential (MEP)s from transcranial magnetic stimulation were recorded in the flexor carpi radialis of the non-dominant or affected upper extremity using three different conditions: (A) relaxation; (B) real mirror; and (C) virtual mirror. Moreover, we compared the MEPs from the virtual mirror paradigm using continuous visual feedback or intermittent visual feedback. The rates of amplitude increment and latency decrement of MEPs in both groups were higher during the virtual mirror task than during the real mirror. In healthy subjects and stroke patients, the virtual mirror task with intermittent visual feedback significantly facilitated corticospinal excitability of MEPs compared with continuous visual feedback. Corticospinal excitability was facilitated to a greater extent in the virtual mirror paradigm than in the real mirror and in intermittent visual feedback than in the continuous visual feedback, in both groups. This provides neurophysiological evidence supporting the application of the virtual mirror paradigm using various visual modulation technologies to upper extremity rehabilitation in stroke patients.

Upper extremity rehabilitation of stroke: Facilitation of corticospinal excitability using virtual mirror paradigm

PubMed Central

2012-01-01

Background Several experimental studies in stroke patients suggest that mirror therapy and various virtual reality programs facilitate motor rehabilitation. However, the underlying mechanisms for these therapeutic effects have not been previously described. Objectives We attempted to delineate the changes in corticospinal excitability when individuals were asked to exercise their upper extremity using a real mirror and virtual mirror. Moreover, we attempted to delineate the role of visual modulation within the virtual environment that affected corticospinal excitability in healthy subjects and stroke patients. Methods A total of 18 healthy subjects and 18 hemiplegic patients were enrolled into the study. Motor evoked potential (MEP)s from transcranial magnetic stimulation were recorded in the flexor carpi radialis of the non-dominant or affected upper extremity using three different conditions: (A) relaxation; (B) real mirror; and (C) virtual mirror. Moreover, we compared the MEPs from the virtual mirror paradigm using continuous visual feedback or intermittent visual feedback. Results The rates of amplitude increment and latency decrement of MEPs in both groups were higher during the virtual mirror task than during the real mirror. In healthy subjects and stroke patients, the virtual mirror task with intermittent visual feedback significantly facilitated corticospinal excitability of MEPs compared with continuous visual feedback. Conclusion Corticospinal excitability was facilitated to a greater extent in the virtual mirror paradigm than in the real mirror and in intermittent visual feedback than in the continuous visual feedback, in both groups. This provides neurophysiological evidence supporting the application of the virtual mirror paradigm using various visual modulation technologies to upper extremity rehabilitation in stroke patients. PMID:23035951

Influence of acute stress on spatial tasks in humans.

PubMed

Richardson, Anthony E; VanderKaay Tomasulo, Melissa M

2011-07-06

Few studies have investigated the relationship between stress and spatial performance in humans. In this study, participants were exposed to an acute laboratory stressor (Star Mirror Tracing Task) or a control condition (watching a nature video) and then performed two spatial tasks. In the first task, participants navigated through a virtual reality (VR) environment and then returned to the environment to make directional judgments relating to the learned targets. In the second task, perspective taking, participants made directional judgments to targets after imagined body rotations with respect to a map. Compared to the control condition, participants in the Stress condition showed increases in heart rate and systolic and diastolic blood pressure indicating sympathetic adrenal medulla (SAM) axis activation. Participants in the Stress condition also reported being more anxious, angry, frustrated, and irritated than participants in the Non-Stress condition. Salivary cortisol did not differ between conditions, indicating no significant hypothalamic-pituitary-adrenocortical (HPA) axis involvement. In the VR task, memory encoding was unaffected as directional error was similar in both conditions; however, participants in the Stress condition responded more slowly, which may be due to increases in negative affect, SAM disruption in spatial memory retrieval through catecholamine release, or a combination of both factors. In the perspective taking task, participants were also slower to respond after stress, suggesting interference in the ability to adopt new spatial orientations. Additionally, sex differences were observed in that men had greater accuracy on both spatial tasks, but no significant Sex by Stress condition interactions were demonstrated. Copyright © 2011 Elsevier Inc. All rights reserved.

Multipass optical device and process for gas and analyte determination

DOEpatents

Bernacki, Bruce E [Kennewick, WA

2011-01-25

A torus multipass optical device and method are described that provide for trace level determination of gases and gas-phase analytes. The torus device includes an optical cavity defined by at least one ring mirror. The mirror delivers optical power in at least a radial and axial direction and propagates light in a multipass optical path of a predefined path length.

Mirror reversal and visual rotation are learned and consolidated via separate mechanisms: recalibrating or learning de novo?

PubMed

Telgen, Sebastian; Parvin, Darius; Diedrichsen, Jörn

2014-10-08

Motor learning tasks are often classified into adaptation tasks, which involve the recalibration of an existing control policy (the mapping that determines both feedforward and feedback commands), and skill-learning tasks, requiring the acquisition of new control policies. We show here that this distinction also applies to two different visuomotor transformations during reaching in humans: Mirror-reversal (left-right reversal over a mid-sagittal axis) of visual feedback versus rotation of visual feedback around the movement origin. During mirror-reversal learning, correct movement initiation (feedforward commands) and online corrections (feedback responses) were only generated at longer latencies. The earliest responses were directed into a nonmirrored direction, even after two training sessions. In contrast, for visual rotation learning, no dependency of directional error on reaction time emerged, and fast feedback responses to visual displacements of the cursor were immediately adapted. These results suggest that the motor system acquires a new control policy for mirror reversal, which initially requires extra processing time, while it recalibrates an existing control policy for visual rotations, exploiting established fast computational processes. Importantly, memory for visual rotation decayed between sessions, whereas memory for mirror reversals showed offline gains, leading to better performance at the beginning of the second session than in the end of the first. With shifts in time-accuracy tradeoff and offline gains, mirror-reversal learning shares common features with other skill-learning tasks. We suggest that different neuronal mechanisms underlie the recalibration of an existing versus acquisition of a new control policy and that offline gains between sessions are a characteristic of latter. Copyright © 2014 the authors 0270-6474/14/3413768-12$15.00/0.

Opto-thermal analysis of a lightweighted mirror for solar telescope.

PubMed

Banyal, Ravinder K; Ravindra, B; Chatterjee, S

2013-03-25

In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account for the radiative heating and energy exchange of the mirror with surroundings. The numerical simulations show the non-uniform temperature distribution and associated thermo-elastic distortions of the mirror blank clearly mimicking the underlying discrete geometry of the lightweighted substrate. The computed mechanical deformation data is analyzed with surface polynomials and the optical quality of the mirror is evaluated with the help of a ray-tracing software. The thermal print-through distortions are further shown to contribute to optical figure changes and mid-spatial frequency errors of the mirror surface. A comparative study presented for three commonly used substrate materials, namely, Zerodur, Pyrex and Silicon Carbide (SiC) is relevant to vast area of large optics requirements in ground and space applications.

New method of design of nonimaging concentrators.

PubMed

Miñano, J C; González, J C

1992-06-01

A new method of designing nonimaging concentrators is presented and two new types of concentrators are developed. The first is an aspheric lens, and the second is a lens-mirror combination. A ray tracing of three-dimensional concentrators (with rotational symmetry) is also done, showing that the lens-mirror combination has a total transmission as high as that of the full compound parabolic concentrators, while their depth is much smaller than the classical parabolic mirror-nonimaging concentrator combinations. Another important feature of this concentrator is that the optically active surfaces are not in contact with the receiver, as occurs in other nonimaging concentrators in which the rim of the mirror coincides with the rim of the receiver.

Blind readers break mirror invariance as sighted do.

PubMed

de Heering, Adélaïde; Collignon, Olivier; Kolinsky, Régine

2018-04-01

Mirror invariance refers to a predisposition of humans, including infants and animals, which urge them to consider mirrored images as corresponding to the same object. Yet in order to learn to read a written system that incorporates mirrored letters (e.g., vs. in the Latin alphabet), humans learn to break this perceptual bias. Here we examined the role visual experience and input modality play in the emergence of this bias. To this end, we tested congenital blind (CB) participants in two same-different tactile comparison tasks including pairs of mirrored and non-mirrored Braille letters as well as embossed unfamiliar geometric shapes and Latin letters, and compared their results to those of age-matched sighted participants involved in similar but visually-presented tasks. Sighted participants showed a classical pattern of results for their material of expertise, Latin letters. CB's results signed for their expertise with the Braille script compared to the other two materials that they processed according to an internal frame of reference. They also evidenced that they automatically break mirror invariance for different materials explored through the tactile modality, including Braille letters. Altogether, these results demonstrate that learning to read Braille through the tactile modality allows breaking mirror invariance in a comparable way to what is observed in sighted individuals for the mirrored letters of the Latin alphabet. Copyright © 2018 Elsevier Ltd. All rights reserved.

Personality and physiological reactions to acute psychological stress.

PubMed

Bibbey, Adam; Carroll, Douglas; Roseboom, Tessa J; Phillips, Anna C; de Rooij, Susanne R

2013-10-01

Stable personality traits have long been presumed to have biological substrates, although the evidence relating personality to biological stress reactivity is inconclusive. The present study examined, in a large middle aged cohort (N=352), the relationship between key personality traits and both cortisol and cardiovascular reactions to acute psychological stress. Salivary cortisol and cardiovascular activity were measured at rest and in response to a psychological stress protocol comprising 5min each of a Stroop task, mirror tracing, and a speech task. Participants subsequently completed the Big Five Inventory to assess neuroticism, agreeableness, openness to experience, extraversion, and conscientiousness. Those with higher neuroticism scores exhibited smaller cortisol and cardiovascular stress reactions, whereas participants who were less agreeable and less open had smaller cortisol and cardiac reactions to stress. These associations remained statistically significant following adjustment for a range of potential confounding variables. Thus, a negative personality disposition would appear to be linked to diminished stress reactivity. These findings further support a growing body of evidence which suggests that blunted stress reactivity may be maladaptive. Copyright © 2012 Elsevier B.V. All rights reserved.

FEM analysis of bonding process used for minimization of deformation of optical surface under Metis coronagraph mirrors manufacturing

NASA Astrophysics Data System (ADS)

Procháska, F.; Vít, T.; Matoušek, O.; Melich, R.

2016-11-01

High demands on the final surfaces micro-roughness as well as great shape accuracy have to be achieved under the manufacturing process of the precise mirrors for Metis orbital coronagraph. It is challenging engineering task with respect to lightweight design of the mirrors and resulting objectionable optical surface shape stability. Manufacturing of such optical elements is usually affected by number of various effects. Most of them are caused by instability of temperature field. It is necessary to explore, comprehend and consequently minimize all thermo - mechanical processes which take place during mirror cementing, grinding and polishing processes to minimize the optical surface deformation. Application of FEM simulation was proved as a useful tool to help to solve this task. FEM simulations were used to develop and virtually compare different mirror holders to minimize the residual stress generated by temperature changes and to suppress the shape deformation of the optical surface below the critical limit of about 100 nm.

Spectral radiation analyses of the GOES solar illuminated hexagonal cell scan mirror back

NASA Technical Reports Server (NTRS)

Fantano, Louis G.

1993-01-01

A ray tracing analytical tool has been developed for the simulation of spectral radiation exchange in complex systems. Algorithms are used to account for heat source spectral energy, surface directional radiation properties, and surface spectral absorptivity properties. This tool has been used to calculate the effective solar absorptivity of the geostationary operational environmental satellites (GOES) scan mirror in the calibration position. The development and design of Sounder and Imager instruments on board GOES is reviewed and the problem of calculating the effective solar absorptivity associated with the GOES hexagonal cell configuration is presented. The analytical methodology based on the Monte Carlo ray tracing technique is described and results are presented and verified by experimental measurements for selected solar incidence angles.

Laser multipass system with interior cell configuration.

PubMed

Borysow, Jacek; Kostinski, Alexander; Fink, Manfred

2011-10-20

We ask whether it is possible to restore a multipass system alignment after a gas cell is inserted in the central region. Indeed, it is possible, and we report on a remarkably simple rearrangement of a laser multipass system, composed of two spherical mirrors and a gas cell with flat windows in the middle. For example, for a window of thickness d and refractive index of n, adjusting the mirror separation by ≈2d(1-1/n) is sufficient to preserve the laser beam alignment and tracing. This expression is in agreement with ray-tracing computations and our laboratory experiment. Insofar as our solution corrects for spherical aberrations, it may also find applications in microscopy. © 2011 Optical Society of America

Impact of HIV and a history of marijuana dependence on procedural learning among individuals with a history of substance dependence

PubMed Central

Gonzalez, Raul; Schuster, Randi M.; Vassileva, Jasmin; Martin, Eileen M.

2013-01-01

Marijuana (MJ) use and HIV infection are both associated with neurocognitive deficits, yet there is little research to date examining their interactions, specifically how they pertain to procedural learning (PL). We examined a sample of 86 individuals with a history of dependence for multiple substances who underwent a comprehensive evaluation including measures of mental health, substance use history, and three measures of PL: the photoelectric Rotary Pursuit Task (RPT), the Star Mirror Tracing Task (SMT), and the Weather Prediction Task (WPT). We found that a positive HIV serostatus and a history of marijuana dependence were both independently associated with overall poorer performance on the SMT and RPT in this sample of individuals with a history of dependence for multiple substances. Rate of improvement across trial blocks did not differ as a function of HIV serostatus or history of marijuana dependence. Although we found no significant HIV × MJ interaction for any of the PL tasks, we did observe evidence of additive negative effects from HIV and a history of marijuana dependence on overall performance on the SMT and RPT, but not the WPT. The findings suggest that complex motor skills are adversely affected among abstinent polysubstance users with a history of marijuana dependence and that such deficits are compounded by HIV. PMID:21480022

Memory and consciousness: trace distinctiveness in memory retrievals.

PubMed

Brunel, Lionel; Oker, Ali; Riou, Benoit; Versace, Rémy

2010-12-01

The aim of this article was to provide experimental evidence that classical dissociation between levels of consciousness associated with memory retrieval (i.e., implicit or explicit) can be explained in terms of task dependency and distinctiveness of traces. In our study phase, we manipulated the level of isolation (partial vs. global) of the memory trace by means of an isolation paradigm (isolated words among non-isolated words). We then tested these two types of isolation in a series of tasks of increasing complexity: a lexical decision task, a recognition task, and a free recall task. The main result of this study was that distinctiveness effects were observed as a function of the type of isolation (level of isolation) and the nature of the task. We concluded that trace distinctiveness improves subsequent access to the trace, while the level of trace distinctiveness also appears to determine the possibility of conscious or explicit retrieval. Copyright © 2010 Elsevier Inc. All rights reserved.

Reflectometer design using nonimaging optics

NASA Astrophysics Data System (ADS)

Snail, Keith A.

1987-12-01

A new type of two-stage reflectometer is proposed for the measurement of directional hemispherical reflectance. The proposed reflectometer consists of a primary collecting mirror coupled to a secondary mirror chosen to eliminate the Fresnel variation of the detector (or source) response. The secondary mirror shape needed is an inverted nonimaging compound parabolic concentrator (CPC). For direct mode operation, the detector is placed at the larger CPC aperture. Ray tracing of a CPC/ellipsoid reflectometer indicates that the throughput is high and isotropic. Design trade-offs and two-stage reflectometers employing a hemisphere and dual paraboloid primary are also discussed.

Reflectometer design using nonimaging optics.

PubMed

Snail, K A

1987-12-15

A new type of two-stage reflectometer is proposed for the measurement of directional hemispherical reflectance. The proposed reflectometer consists of a primary collecting mirror coupled to a secondary mirror chosen to eliminate the Fresnel variation of the detector (or source) response. The secondary mirror shape needed is an inverted nonimaging compound parabolic concentrator (CPC). For direct mode operation, the detector is placed at the larger CPC aperture. Ray tracing of a CPC/ellipsoid reflectometer indicates that the throughput is high and isotropic. Design trade-offs and two-stage reflectometers employing a hemisphere and dual paraboloid primary are also discussed.

Design and analysis of multilayer x ray/XUV microscope

NASA Technical Reports Server (NTRS)

Shealy, David L.

1990-01-01

The design and analysis of a large number of normal incidence multilayer x ray microscopes based on the spherical mirror Schwarzschild configuration is examined. Design equations for the spherical mirror Schwarzschild microscopes are summarized and used to evaluate mirror parameters for microscopes with magnifications ranging from 2 to 50x. Ray tracing and diffraction analyses are carried out for many microscope configurations to determine image resolution as a function of system parameters. The results are summarized in three publication included herein. A preliminary study of advanced reflecting microscope configurations, where aspherics are used in place of the spherical microscope mirror elements, has indicated that the aspherical elements will improve off-axis image resolution and increase the effective field of view.

Mathematical Design Optimization of Wide-Field X-ray Telescopes: Mirror Nodal Positions and Detector Tilts

NASA Technical Reports Server (NTRS)

Elsner, R. F.; O'Dell, S. L.; Ramsey, B. D.; Weisskopf, M. C.

2011-01-01

We describe a mathematical formalism for determining the mirror shell nodal positions and detector tilts that optimize the spatial resolution averaged over a field-of-view for a nested x-ray telescope, assuming known mirror segment surface prescriptions and known detector focal surface. The results are expressed in terms of ensemble averages over variable combinations of the ray positions and wave vectors in the flat focal plane intersecting the optical axis at the nominal on-axis focus, which can be determined by Monte-Carlo ray traces of the individual mirror shells. This work is part of our continuing efforts to provide analytical tools to aid in the design process for wide-field survey x-ray astronomy missions.

Mathematical Design Optimization of Wide-Field X-ray Telescopes: Mirror Nodal Positions and Detector Tilts

NASA Technical Reports Server (NTRS)

Elsner, Ronald; O'Dell, Stephen; Ramsey, Brian; Weisskopf, Martin

2011-01-01

We describe a mathematical formalism for determining the mirror shell nodal positions and detector tilts that optimize the spatial resolution averaged over a field-of-view for a nested x-ray telescope, assuming known mirror segment surface prescriptions and known detector focal surface. The results are expressed in terms of ensemble averages over variable combinations of the ray positions and wavevectors in the flat focal plane intersecting the optical axis at the nominal on-axis focus, which can be determined by Monte-Carlo ray traces of the individual mirror shells. This work is part of our continuing efforts to provide analytical tools to aid in the design process for wide-field survey x-ray astronomy missions.

Analysis of stray radiation for infrared optical system

NASA Astrophysics Data System (ADS)

Li, Yang; Zhang, Tingcheng; Liao, Zhibo; Mu, Shengbo; Du, Jianxiang; Wang, Xiangdong

2016-10-01

Based on the theory of radiation energy transfer in the infrared optical system, two methods for stray radiation analysis caused by interior thermal radiation in infrared optical system are proposed, one of which is important sampling method technique using forward ray trace, another of which is integral computation method using reverse ray trace. The two methods are discussed in detail. A concrete infrared optical system is provided. Light-tools is used to simulate the passage of radiation from the mirrors and mounts. Absolute values of internal irradiance on the detector are received. The results shows that the main part of the energy on the detector is due to the critical objects which were consistent with critical objects obtained by reverse ray trace, where mirror self-emission contribution is about 87.5% of the total energy. Corresponding to the results, the irradiance on the detector calculated by the two methods are in good agreement. So the validity and rationality of the two methods are proved.

Understanding what is visible in a mirror or through a window before and after updating the position of an object.

PubMed

Bertamini, Marco

2014-01-01

In the Venus effect observers assume that Venus is admiring her own reflection in the mirror (Bertamini et al., 2003a). However, since the observer sees her face in the mirror, Venus is actually looking at the reflection of the painter. This effect is general because it is not specific to paintings or to images of people. This study tests whether people have difficulties in estimating what is visible from a given viewpoint using a paper and pencil task. Participants (N = 80) judged what is visible in a scene that could include a mirror or an aperture. The object in the scene (a train) was already located in front of the mirror or behind the aperture, or the same object had to be imagined to move to that location. The hypothesis was that this extra step (spatial transformation) is always part of how people reason about mirrors because they have to imagine the location of the reflection based on the location of the physical object. If so, this manipulation would equate the difficulty of the mirror and of the aperture conditions. Results show that performance on the paper and pencil task was better than expected, probably because of the asymmetric nature of the object used. However, an additional cost in reasoning about mirrors was confirmed.

Motion tracking and electromyography-assisted identification of mirror hand contributions to functional near-infrared spectroscopy images acquired during a finger-tapping task performed by children with cerebral palsy.

PubMed

Hervey, Nathan; Khan, Bilal; Shagman, Laura; Tian, Fenghua; Delgado, Mauricio R; Tulchin-Francis, Kirsten; Shierk, Angela; Roberts, Heather; Smith, Linsley; Reid, Dahlia; Clegg, Nancy J; Liu, Hanli; MacFarlane, Duncan; Alexandrakis, George

2014-10-01

Recent studies have demonstrated functional near-infrared spectroscopy (fNIRS) to be a viable and sensitive method for imaging sensorimotor cortex activity in children with cerebral palsy (CP). However, during unilateral finger tapping, children with CP often exhibit unintended motions in the nontapping hand, known as mirror motions, which confuse the interpretation of resulting fNIRS images. This work presents a method for separating some of the mirror motion contributions to fNIRS images and demonstrates its application to fNIRS data from four children with CP performing a finger-tapping task with mirror motions. Finger motion and arm muscle activity were measured simultaneously with fNIRS signals using motion tracking and electromyography (EMG), respectively. Subsequently, subject-specific regressors were created from the motion capture or EMG data and independent component analysis was combined with a general linear model to create an fNIRS image representing activation due to the tapping hand and one image representing activation due to the mirror hand. The proposed method can provide information on how mirror motions contribute to fNIRS images, and in some cases, it helps remove mirror motion contamination from the tapping hand activation images.

Motion tracking and electromyography-assisted identification of mirror hand contributions to functional near-infrared spectroscopy images acquired during a finger-tapping task performed by children with cerebral palsy

PubMed Central

Hervey, Nathan; Khan, Bilal; Shagman, Laura; Tian, Fenghua; Delgado, Mauricio R.; Tulchin-Francis, Kirsten; Shierk, Angela; Roberts, Heather; Smith, Linsley; Reid, Dahlia; Clegg, Nancy J.; Liu, Hanli; MacFarlane, Duncan; Alexandrakis, George

2014-01-01

Abstract. Recent studies have demonstrated functional near-infrared spectroscopy (fNIRS) to be a viable and sensitive method for imaging sensorimotor cortex activity in children with cerebral palsy (CP). However, during unilateral finger tapping, children with CP often exhibit unintended motions in the nontapping hand, known as mirror motions, which confuse the interpretation of resulting fNIRS images. This work presents a method for separating some of the mirror motion contributions to fNIRS images and demonstrates its application to fNIRS data from four children with CP performing a finger-tapping task with mirror motions. Finger motion and arm muscle activity were measured simultaneously with fNIRS signals using motion tracking and electromyography (EMG), respectively. Subsequently, subject-specific regressors were created from the motion capture or EMG data and independent component analysis was combined with a general linear model to create an fNIRS image representing activation due to the tapping hand and one image representing activation due to the mirror hand. The proposed method can provide information on how mirror motions contribute to fNIRS images, and in some cases, it helps remove mirror motion contamination from the tapping hand activation images. PMID:26157980

Hubble Space Telescope: SRM/QA observations and lessons learned

NASA Technical Reports Server (NTRS)

Rodney, George A.

1990-01-01

The Hubble Space Telescope (HST) Optical Systems Board of Investigation was established on July 2, 1990 to review, analyze, and evaluate the facts and circumstances regarding the manufacture, development, and testing of the HST Optical Telescope Assembly (OTA). Specifically, the board was tasked to ascertain what caused the spherical aberration and how it escaped notice until on-orbit operation. The error that caused the on-orbit spherical aberration in the primary mirror was traced to the assembly process of the Reflective Null Corrector, one of the three Null Correctors developed as special test equipment (STE) to measure and test the primary mirror. Therefore, the safety, reliability, maintainability, and quality assurance (SRM&QA) investigation covers the events and the overall product assurance environment during the manufacturing phase of the primary mirror and Null Correctors (from 1978 through 1981). The SRM&QA issues that were identified during the HST investigation are summarized. The crucial product assurance requirements (including nonconformance processing) for the HST are examined. The history of Quality Assurance (QA) practices at Perkin-Elmer (P-E) for the period under investigation are reviewed. The importance of the information management function is discussed relative to data retention/control issues. Metrology and other critical technical issues also are discussed. The SRM&QA lessons learned from the investigation are presented along with specific recommendations. Appendix A provides the MSFC SRM&QA report. Appendix B provides supplemental reference materials. Appendix C presents the findings of the independent optical consultants, Optical Research Associates (ORA). Appendix D provides further details of the fault-tree analysis portion of the investigation process.

Overestimation of the Projected Size of Objects on the Surface of Mirrors and Windows

ERIC Educational Resources Information Center

Lawson, Rebecca; Bertamini, Marco; Liu, Dan

2007-01-01

Four experiments investigated judgments of the size of projections of objects on the glass surface of mirrors and windows. The authors tested different ways of explaining the task to overcome the difficulty that people had in understanding what the projection was, and they varied the distance of the observer and the object to the mirror or window…

Solar Thermal Concept Evaluation

NASA Technical Reports Server (NTRS)

Hawk, Clark W.; Bonometti, Joseph A.

1995-01-01

Concentrated solar thermal energy can be utilized in a variety of high temperature applications for both terrestrial and space environments. In each application, knowledge of the collector and absorber's heat exchange interaction is required. To understand this coupled mechanism, various concentrator types and geometries, as well as, their relationship to the physical absorber mechanics were investigated. To conduct experimental tests various parts of a 5,000 watt, thermal concentrator, facility were made and evaluated. This was in anticipation at a larger NASA facility proposed for construction. Although much of the work centered on solar thermal propulsion for an upper stage (less than one pound thrust range), the information generated and the facility's capabilities are applicable to material processing, power generation and similar uses. The numerical calculations used to design the laboratory mirror and the procedure for evaluating other solar collectors are presented here. The mirror design is based on a hexagonal faceted system, which uses a spherical approximation to the parabolic surface. The work began with a few two dimensional estimates and continued with a full, three dimensional, numerical algorithm written in FORTRAN code. This was compared to a full geometry, ray trace program, BEAM 4, which optimizes the curvatures, based on purely optical considerations. Founded on numerical results, the characteristics of a faceted concentrator were construed. The numerical methodologies themselves were evaluated and categorized. As a result, the three-dimensional FORTRAN code was the method chosen to construct the mirrors, due to its overall accuracy and superior results to the ray trace program. This information is being used to fabricate and subsequently, laser map the actual mirror surfaces. Evaluation of concentrator mirrors, thermal applications and scaling the results of the 10 foot diameter mirror to a much larger concentrator, were studied. Evaluations, recommendations and pit falls regarding the structure, materials and facility design are presented.

Exploring the impact of visual and movement based priming on a motor intervention in the acute phase post-stroke in persons with severe hemiparesis of the upper extremity.

PubMed

Patel, Jigna; Qiu, Qinyin; Yarossi, Mathew; Merians, Alma; Massood, Supriya; Tunik, Eugene; Adamovich, Sergei; Fluet, Gerard

2017-07-01

Explore the potential benefits of using priming methods prior to an active hand task in the acute phase post-stroke in persons with severe upper extremity hemiparesis. Five individuals were trained using priming techniques including virtual reality (VR) based visual mirror feedback and contralaterally controlled passive movement strategies prior to training with an active pinch force modulation task. Clinical, kinetic, and neurophysiological measurements were taken pre and post the training period. Clinical measures were taken at six months post training. The two priming simulations and active training were well tolerated early after stroke. Priming effects were suggested by increased maximal pinch force immediately after visual and movement based priming. Despite having no clinically observable movement distally, the subjects were able to volitionally coordinate isometric force and muscle activity (EMG) in a pinch tracing task. The Root Mean Square Error (RMSE) of force during the pinch trace task gradually decreased over the training period suggesting learning may have occurred. Changes in motor cortical neurophysiology were seen in the unaffected hemisphere using Transcranial Magnetic Stimulation (TMS) mapping. Significant improvements in motor recovery as measured by the Action Research Arm Test (ARAT) and the Upper Extremity Fugl Meyer Assessment (UEFMA) were demonstrated at six months post training by three of the five subjects. This study suggests that an early hand-based intervention using visual and movement based priming activities and a scaled motor task allows participation by persons without the motor control required for traditionally presented rehabilitation and testing. Implications for Rehabilitation Rehabilitation of individuals with severely paretic upper extremities after stroke is challenging due to limited movement capacity and few options for therapeutic training. Long-term functional recovery of the arm after stroke depends on early return of active hand control, establishing a need for acute training methods focused distally. This study demonstrates the feasibility of an early hand-based intervention using virtual reality based priming and scaled motor activities which can allow for participation by persons without the motor control required for traditionally presented rehabilitation and testing.

Second metrology round-robin of APS, ESRF and SPring-8 laboratories of elliptical and spherical hard-x-ray mirrors.

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

Rommeveaux, A.; Assoufid, L.; Ohashi, H.

2007-01-01

The first series of metrology round-robin measurements carried out in 2005 at the APS, ESRF and SPring-8 metrology laboratories involving two flat x-ray mirrors and a cylindrical x-ray mirror has shown excellent agreement among the three facilities Long Trace Profilers (LTP) despite their architectural differences. Because of the growing interest in diffraction-limited hard x-ray K-B focusing mirrors, it was decided to extend the round robin measurements to spherical and aspheric x-ray mirrors. The strong surface slope variation of these mirrors presents a real challenge to LTP. As a result, new LTP measurement protocol has to be developed and implemented tomore » ensure measurement accuracy and consistency. In this paper, different measurement techniques and procedures will be described, the results will be discussed, and comparison will be extended to micro-stitching interferometry measurements performed at Osaka University, Japan.« less

Design of Off-Axis PIAACMC Mirrors

NASA Technical Reports Server (NTRS)

Pluzhnik, Eugene; Guyon, Olivier; Belikov, Ruslan; Kern, Brian; Bendek, Eduardo

2015-01-01

The Phase-Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) provides an efficient way to control diffraction propagation effects caused by the central obstruction/segmented mirrors of the telescope. PIAACMC can be optimized in a way that takes into account both chromatic diffraction effects caused by the telescope obstructed aperture and tip/tilt sensitivity of the coronagraph. As a result, unlike classic PIAA, the PIAACMC mirror shapes are often slightly asymmetric even for an on-axis configuration and require more care in calculating off-axis shapes when an off-axis configuration is preferred. A method to design off-axis PIAA mirror shapes given an on-axis mirror design is presented. The algorithm is based on geometrical ray tracing and is able to calculate off-axis PIAA mirror shapes for an arbitrary geometry of the input and output beams. The method is demonstrated using the third generation PIAACMC design for WFIRST-AFTA (Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets) telescope. Geometrical optics design issues related to the off-axis diffraction propagation effects are also discussed.

Understanding emotions in others: mirror neuron dysfunction in children with autism spectrum disorders.

PubMed

Dapretto, Mirella; Davies, Mari S; Pfeifer, Jennifer H; Scott, Ashley A; Sigman, Marian; Bookheimer, Susan Y; Iacoboni, Marco

2006-01-01

To examine mirror neuron abnormalities in autism, high-functioning children with autism and matched controls underwent fMRI while imitating and observing emotional expressions. Although both groups performed the tasks equally well, children with autism showed no mirror neuron activity in the inferior frontal gyrus (pars opercularis). Notably, activity in this area was inversely related to symptom severity in the social domain, suggesting that a dysfunctional 'mirror neuron system' may underlie the social deficits observed in autism.

Microwave limb sounder. [measuring trace gases in the upper atmosphere

NASA Technical Reports Server (NTRS)

Gustincic, J. J. (Inventor)

1981-01-01

Trace gases in the upper atmosphere can be measured by comparing spectral noise content of limb soundings with the spectral noise content of cold space. An offset Cassegrain antenna system and tiltable input mirror alternately look out at the limb and up at cold space at an elevation angle of about 22. The mirror can also be tilted to look at a black body calibration target. Reflection from the mirror is directed into a radiometer whose head functions as a diplexer to combine the input radiation and a local ocillator (klystron) beam. The radiometer head is comprised of a Fabry-Perot resonator consisting of two Fabry-Perot cavities spaced a number of half wavelengths apart. Incoming radiation received on one side is reflected and rotated 90 deg in polarization by the resonator so that it will be reflected by an input grid into a mixer, while the klystron beam received on the other side is also reflected and rotated 90 deg, but not without passing some energy to be reflected by the input grid into the mixer.

Optical design of the National Ignition Facility main laser and switchyard/target area beam transport systems

NASA Astrophysics Data System (ADS)

Miller, John L.; English, R. Edward, Jr.; Korniski, Ronald J.; Rodgers, J. Michael

1999-07-01

The optical design of the main laser and transport mirror sections of the National Ignition Facility are described. For the main laser the configuration, layout constraints, multiple beam arrangement, pinhole layout and beam paths, clear aperture budget, ray trace models, alignment constraints, lens designs, wavefront performance, and pupil aberrations are discussed. For the transport mirror system the layout, alignment controls and clear aperture budget are described.

Miniature Trace Gas Detector Based on Microfabricated Optical Resonators

NASA Technical Reports Server (NTRS)

Aveline, David C.; Yu, Nan; Thompson, Robert J.; Strekalov, Dmitry V.

2013-01-01

While a variety of techniques exist to monitor trace gases, methods relying on absorption of laser light are the most commonly used in terrestrial applications. Cavity-enhanced absorption techniques typically use high-reflectivity mirrors to form a resonant cavity, inside of which a sample gas can be analyzed. The effective absorption length is augmented by the cavity's high quality factor, or Q, because the light reflects many times between the mirrors. The sensitivity of such mirror-based sensors scales with size, generally making them somewhat bulky in volume. Also, specialized coatings for the high-reflectivity mirrors have limited bandwidth (typically just a few nanometers), and the delicate mirror surfaces can easily be degraded by dust or chemical films. As a highly sensitive and compact alternative, JPL is developing a novel trace gas sensor based on a monolithic optical resonator structure that has been modified such that a gas sample can be directly injected into the cavity. This device concept combines ultra-high Q optical whispering gallery mode resonators (WGMR) with microfabrication technology used in the semiconductor industry. For direct access to the optical mode inside a resonator, material can be precisely milled from its perimeter, creating an open gap within the WGMR. Within this open notch, the full optical mode of the resonator can be accessed. While this modification may limit the obtainable Q, calculations show that the reduction is not significant enough to outweigh its utility for trace gas detection. The notch can be milled from the high- Q crystalline WGMR with a focused ion beam (FIB) instrument with resolution much finer than an optical wavelength, thereby minimizing scattering losses and preserving the optical quality. Initial experimental demonstrations have shown that these opened cavities still support high-Q whispering gallery modes. This technology could provide ultrasensitive detection of a variety of molecular species in an extremely compact and robust package. With this type of modified WGMR, one can inject a gas sample into the open gap, allowing highly sensitive trace molecule detection within a roughly 1-cm volume. Other critical components of the instrument, such as the detector and a semiconductor laser, could be directly packaged with the resonator so as to not significantly increase the size of the device. Besides its low mass, volume, and power consumption, the monolithic design makes these resonators intrinsically robust devices, capable of handling significant temperature excursions, without moving parts to wear out or delicate coatings that can be easily damaged. A sensor could integrate with microfluidics technology for a chip-scale device. It could be mounted to the end of a deployable arm, or inserted into a borehole. Also, a network of individual sensors could be dispersed to monitor conditions over a wide region

The backward ray tracing with effective solar brightness used to simulate the concentrated flux map of a solar tower concentrator

NASA Astrophysics Data System (ADS)

Guo, Minghuan; Sun, Feihu; Wang, Zhifeng

2017-06-01

The solar tower concentrator is mainly composed of the central receiver on the tower top and the heliostat field around the tower. The optical efficiencies of a solar tower concentrator are important to the whole thermal performance of the solar tower collector, and the aperture plane of a cavity receiver or the (inner or external) absorbing surface of any central receiver is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated time-changing solar flux density distributions on the flat or curved receiving surface of the collector, with main optical errors considered. The transient concentrated solar flux on the receiving surface is the superimposition of the flux density distributions of all the normal working heliostats in the field. In this paper, we will mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the flux density map on the receiving-surface. For BRT, bundles of rays are launched at the receiving-surface points of interest, strike directly on the valid cell centers among the uniformly sampled mirror cell centers in the mirror surface of the heliostats, and then direct to the effective solar cone around the incident sun beam direction after reflection. All the optical errors are convoluted into the effective solar cone. The brightness distribution of the effective solar cone is here supposed to be circular Gaussian type. The mirror curvature can be adequately formulated by certain number of local normal vectors at the mirror cell centers of a heliostat. The shading & blocking mirror region of a heliostat by neighbor heliostats and also the solar tower shading on the heliostat mirror are all computed on the flat-ground-plane platform, i.e., projecting the mirror contours and the envelope cylinder of the tower onto the horizontal ground plane along the sun-beam incident direction or along the reflection directions. If the shading projection of a sampled mirror point of the current heliostat is inside the shade cast of a neighbor heliostat or in the shade cast of the tower, this mirror point should be shaded from the incident sun beam. A code based on this new ray tracing method for the 1MW Badaling solar tower power plant in Beijing has been developed using MATLAB. There are 100 azimuth-elevation tracking heliostats in the solar field and the total tower is 118 meters high. The mirror surface of the heliostats is 10m wide and 10m long, it is composed of 8 rows × 8 columns of square mirror facets and each mirror facet has the size of 1.25m×1.25m. This code also was verified by two sets of sun-beam concentrating experiments of the heliostat field on the June 14, 2015. One set of optical experiments were conducted between some typical heliostats to verify the shading & blocking computation of the code, since shading & blocking computation is the most complicated, time-consuming and important optical computing section of the code. The other set of solar concentrating tests were carried out on the field center heliostat (No. 78) to verify the simulated the solar flux images on the white target region of the northern wall of the tower. The target center is 74.5 m high to the ground plane.

Reasoning About Visibility in Mirrors: A Comparison Between a Human Observer and a Camera.

PubMed

Bertamini, Marco; Soranzo, Alessandro

2018-01-01

Human observers make errors when predicting what is visible in a mirror. This is true for perception with real mirrors as well as for reasoning about mirrors shown in diagrams. We created an illustration of a room, a top-down view, with a mirror on a wall and objects (nails) on the opposite wall. The task was to select which nails were visible in the mirror from a given position (viewpoint). To study the importance of the social nature of the viewpoint, we divided the sample ( N = 108) in two groups. One group ( n = 54) were tested with a scene in which there was the image of a person. The other group ( n = 54) were tested with the same scene but with a camera replacing the person. Participants were instructed to think about what would be captured by a camera on a tripod. This manipulation tests the effect of social perspective-taking in reasoning about mirrors. As predicted, performance on the task shows an overestimation of what can be seen in a mirror and a bias to underestimate the role of the different viewpoints, that is, a tendency to treat the mirror as if it captures information independently of viewpoint. In terms of the comparison between person and camera, there were more errors for the camera, suggesting an advantage for evaluating a human viewpoint as opposed to an artificial viewpoint. We suggest that social mechanisms may be involved in perspective-taking in reasoning rather than in automatic attention allocation.

An Omnidirectional Vision Sensor Based on a Spherical Mirror Catadioptric System.

PubMed

Barone, Sandro; Carulli, Marina; Neri, Paolo; Paoli, Alessandro; Razionale, Armando Viviano

2018-01-31

The combination of mirrors and lenses, which defines a catadioptric sensor, is widely used in the computer vision field. The definition of a catadioptric sensors is based on three main features: hardware setup, projection modelling and calibration process. In this paper, a complete description of these aspects is given for an omnidirectional sensor based on a spherical mirror. The projection model of a catadioptric system can be described by the forward projection task (FP, from 3D scene point to 2D pixel coordinates) and backward projection task (BP, from 2D coordinates to 3D direction of the incident light). The forward projection of non-central catadioptric vision systems, typically obtained by using curved mirrors, is usually modelled by using a central approximation and/or by adopting iterative approaches. In this paper, an analytical closed-form solution to compute both forward and backward projection for a non-central catadioptric system with a spherical mirror is presented. In particular, the forward projection is reduced to a 4th order polynomial by determining the reflection point on the mirror surface through the intersection between a sphere and an ellipse. A matrix format of the implemented models, suitable for fast point clouds handling, is also described. A robust calibration procedure is also proposed and applied to calibrate a catadioptric sensor by determining the mirror radius and center with respect to the camera.

An Omnidirectional Vision Sensor Based on a Spherical Mirror Catadioptric System

PubMed Central

Barone, Sandro; Carulli, Marina; Razionale, Armando Viviano

2018-01-01

The combination of mirrors and lenses, which defines a catadioptric sensor, is widely used in the computer vision field. The definition of a catadioptric sensors is based on three main features: hardware setup, projection modelling and calibration process. In this paper, a complete description of these aspects is given for an omnidirectional sensor based on a spherical mirror. The projection model of a catadioptric system can be described by the forward projection task (FP, from 3D scene point to 2D pixel coordinates) and backward projection task (BP, from 2D coordinates to 3D direction of the incident light). The forward projection of non-central catadioptric vision systems, typically obtained by using curved mirrors, is usually modelled by using a central approximation and/or by adopting iterative approaches. In this paper, an analytical closed-form solution to compute both forward and backward projection for a non-central catadioptric system with a spherical mirror is presented. In particular, the forward projection is reduced to a 4th order polynomial by determining the reflection point on the mirror surface through the intersection between a sphere and an ellipse. A matrix format of the implemented models, suitable for fast point clouds handling, is also described. A robust calibration procedure is also proposed and applied to calibrate a catadioptric sensor by determining the mirror radius and center with respect to the camera. PMID:29385051

Advanced Mirror Technology Development (AMTD) Project Status

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2014-01-01

To date, AMTD Phase 1 has accomplished all of its technical tasks on-schedule and on-budget. AMTD was awarded a Phase 2 contract. We are now performing Phase 2 tasks along with those tasks continued from Phase 1.

Topical Meeting on Optics in Adverse Environments

DTIC Science & Technology

1987-10-31

Laboratory. (, 21) addrtwses the mount att3chrnicnt and mount zsZesrto -ptiral design to minimb’e 6Lgradition of * ig.; t 2:15J1-e’ Pipe we~gttt mirror at...100 K wi’h and without a Id 5~c mount WCJ# caIed Opdcs for Higr Powered Lase Appkia- support and mirror attachments. Keyise demonstrteed tiom.patrick...J. ", nhrey, TRW. (15 ;73) by this task arm. mirror cO0al perfc.mtance toofli temperature to iGI) K, str3i.free mirror mect-it attachment

Visual feedback-related changes in ipsilateral cortical excitability during unimanual movement: Implications for mirror therapy.

PubMed

Reissig, Paola; Garry, Michael I; Summers, Jeffery J; Hinder, Mark R

2014-01-01

Provision of a mirror image of a hand undertaking a motor task (i.e., mirror therapy) elicits behavioural improvements in the inactive hand. A greater understanding of the neural mechanisms underpinning this phenomenon is required to maximise its potential for rehabilitation across the lifespan, e.g., following hemiparesis or unilateral weakness. Young and older participants performed unilateral finger abductions with no visual feedback, with feedback of the active or passive hands, or with a mirror image of the active hand. Transcranial magnetic stimulation was used to assess feedback-related changes in two neurophysiological measures thought to be involved in inter-manual transfer of skill, namely corticospinal excitability (CSE) and intracortical inhibition (SICI) in the passive hemisphere. Task performance led to CSE increases, accompanied by decreases of SICI, in all visual feedback conditions relative to rest. However, the changes due to mirror feedback were not significantly different to those observed in the other (more standard) visual conditions. Accordingly, the unimanual motor action itself, rather than modifications in visual feedback, appears more instrumental in driving changes in CSE and SICI. Therefore, changes in CSE and SICI are unlikely to underpin the behavioural benefits of mirror therapy. We discuss implications for rehabilitation and directions of future research.

The effect of obesity on inflammatory cytokine and leptin production following acute mental stress.

PubMed

Caslin, H L; Franco, R L; Crabb, E B; Huang, C J; Bowen, M K; Acevedo, E O

2016-02-01

Obesity may contribute to cardiovascular disease (CVD) risk by eliciting chronic systemic inflammation and impairing the immune response to additional stressors. There has been little assessment of the effect of obesity on psychological stress, an independent risk factor for CVD. Therefore, it was of interest to examine interleukin-6, tumor necrosis factor-α, interleukin-1β (IL-1β), interleukin-1 receptor antagonist (IL-1Ra), and leptin following an acute mental stress task in nonobese and obese males. Twenty college-aged males (21.3 ± 0.56 years) volunteered to participate in a 20-min Stroop color-word and mirror-tracing task. Subjects were recruited for obese (body mass index: BMI > 30) and nonobese (BMI < 25) groups, and blood samples were collected for enzyme-linked immunosorbent assay analysis. The acute mental stress task elicited an increase in heart rate, catecholamines, and IL-1β in all subjects. Additionally, acute mental stress increased cortisol concentrations in the nonobese group. There was a significant reduction in leptin in obese subjects 30 min posttask compared with a decrease in nonobese subjects 120 min posttask. Interestingly, the relationship between the percent change in leptin and IL-1Ra at 120 min posttask in response to an acute mental stress task was only observed in nonobese individuals. This is the first study to suggest that adiposity in males may impact leptin and inflammatory signaling mechanisms following acute mental stress. © 2015 Society for Psychophysiological Research.

Preliminary evidence for deficits in multisensory integration in autism spectrum disorders: the mirror neuron hypothesis.

PubMed

Oberman, Lindsay M; Ramachandran, Vilayanur S

2008-01-01

Autism is a complex disorder, characterized by social, cognitive, communicative, and motor symptoms. One suggestion, proposed in the current study, to explain the spectrum of symptoms is an underlying impairment in multisensory integration (MSI) systems such as a mirror neuron-like system. The mirror neuron system, thought to play a critical role in skills such as imitation, empathy, and language can be thought of as a multisensory system, converting sensory stimuli into motor representations. Consistent with this, we report preliminary evidence for deficits in a task thought to tap into MSI--"the bouba-kiki task" in children with ASD. The bouba-kiki effect is produced when subjects are asked to pair nonsense shapes with nonsense "words". We found that neurotypical children chose the nonsense "word" whose phonemic structure corresponded with the visual shape of the stimuli 88% of the time. This is presumably because of mirror neuron-like multisensory systems that integrate the visual shape with the corresponding motor gestures used to pronounce the nonsense word. Surprisingly, individuals with ASD only chose the corresponding name 56% of the time. The poor performance by the ASD group on this task suggests a deficit in MSI, perhaps related to impaired MSI brain systems. Though this is a behavioral study, it provides a testable hypothesis for the communication impairments in children with ASD that implicates a specific neural system and fits well with the current findings suggesting an impairment in the mirror systems in individuals with ASD.

Differential relations between youth internalizing/externalizing problems and cortisol responses to performance vs. interpersonal stress.

PubMed

Laurent, Heidemarie; Vergara-Lopez, Chrystal; Stroud, Laura R

2016-09-01

Efforts to define hypothalamic-pituitary-adrenal (HPA) axis profiles conferring risk for psychopathology have yielded inconclusive results, perhaps in part due to limited assessment of the stress response. In particular, research has typically focused on HPA responses to performance tasks, while neglecting the interpersonal stressors that become salient during adolescence. In this study we investigated links between psychosocial adjustment - youth internalizing and externalizing problems, as well as competence - and HPA responses to both performance and interpersonal stressors in a normative sample of children and adolescents. Participants (n = 59) completed a set of performance (public speaking, mental arithmetic, mirror tracing) and/or interpersonal (peer rejection) tasks and gave nine saliva samples, which were assayed for cortisol. Hierarchical linear models of cortisol response trajectories in relation to child behavior checklist (CBCL) scores revealed stressor- and sex-specific associations. Whereas internalizing problems related to earlier peaking, less dynamic cortisol responses to interpersonal stress (across males and females), externalizing problems related to lower, earlier peaking and less dynamic cortisol responses to performance stress for males only, and competence-related to later peaking cortisol responses to interpersonal stress for females only. Implications for understanding contextual stress profiles underlying different forms of psychopathology are discussed.

Differential Relations Between Youth Internalizing/Externalizing Problems and Cortisol Responses to Performance vs. Interpersonal Stress

PubMed Central

Laurent, Heidemarie; Vergara-Lopez, Chrystal; Stroud, Laura R.

2016-01-01

Efforts to define hypothalamic-pituitary-adrenal (HPA) axis profiles conferring risk for psychopathology have yielded inconclusive results, perhaps in part due to limited assessment of the stress response. In particular, research has typically focused on HPA responses to performance tasks, while neglecting the interpersonal stressors that become salient during adolescence. In this study we investigated links between psychosocial adjustment—youth internalizing and externalizing problems, as well as competence—and HPA responses to both performance and interpersonal stressors in a normative sample of children and adolescents. Participants (n = 59) completed a set of performance (public speaking, mental arithmetic, mirror tracing) and/or interpersonal (peer rejection) tasks and gave 9 saliva samples, which were assayed for cortisol. Hierarchical linear models of cortisol response trajectories in relation to CBCL scores revealed stressor- and sex-specific associations. Whereas internalizing problems related to earlier peaking, less dynamic cortisol responses to interpersonal stress (across males and females), externalizing problems related to lower, earlier peaking, and less dynamic cortisol responses to performance stress for males only, and competence related to later peaking cortisol responses to interpersonal stress for females only. Implications for understanding contextual stress profiles underlying different forms of psychopathology are discussed. PMID:27470923

Finite Element Modeling of a Semi-Rigid Hybrid Mirror and a Highly Actuated Membrane Mirror as Candidates for the Next Generation Space Telescope

NASA Technical Reports Server (NTRS)

Craig, Larry; Jacobson, Dave; Mosier, Gary; Nein, Max; Page, Timothy; Redding, Dave; Sutherlin, Steve; Wilkerson, Gary

2000-01-01

Advanced space telescopes, which will eventually replace the Hubble Space Telescope (HTS), will have apertures of 8 - 20 n. Primary mirrors of these dimensions will have to be foldable to fit into the space launcher. By necessity these mirrors will be extremely light weight and flexible and the historical approaches to mirror designs, where the mirror is made as rigid as possible to maintain figure and to serve as the anchor for the entire telescope, cannot be applied any longer. New design concepts and verifications will depend entirely on analytical methods to predict optical performance. Finite element modeling of the structural and thermal behavior of such mirrors is becoming the tool for advanced space mirror designs. This paper discusses some of the preliminary tasks and study results, which are currently the basis for the design studies of the Next Generation Space Telescope.

Visuomotor learning in cerebellar patients.

PubMed

Timmann, D; Shimansky, Y; Larson, P S; Wunderlich, D A; Stelmach, G E; Bloedel, J R

1996-11-01

The aim of the present study was to demonstrate that patients with pathology affecting substantial regions of the cerebellum can improve their performance in a series of two-dimensional tracing tasks, thus supporting the view that this type of motor behavior can be acquired even when the integrity of this structure is compromised. Eight patients with chronic, isolated cerebellar lesions and eight age- and sex-matched healthy controls were tested. Three patients had mild, five had moderate upper limb ataxia. The experiment was divided into two parts. In the first, subjects traced an irregularly shaped outline over 20 consecutive trials ('Trace 1' task). Next, subjects were asked to redraw the object without any underlying template as a guide ('Memory 1' task). In the second part of the study, subjects were asked to trace a different, irregularly shaped outline over 20 consecutive trials ('Trace 2' task). Next, they were required to redraw it by memory with its axis rotated 90 degrees ('Memory 2' task). In each of the memory tasks the template was placed over the drawn image after each trial and shown to the subjects. The error of performance was determined by calculating three different measurements, each focused on different aspects of the task. Based on these measurements, the cerebellar patients showed improvement in both memory tasks. In the 'Memory 1' task the calculated error decreased significantly for the patients with mild ataxia. In the 'Memory 2' task all cerebellar patients improved their performance substantially enough to reduce significantly the magnitude of all three error measurements. The experiments demonstrate that patients with cerebellar lesions are capable of improving substantially their performance of a complex motor task involving the recall of memorized shapes and the visuomotor control of a tracing movement.

Bendable X-ray Optics at the ALS: Design, Tuning, Performance and Applications

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

Advanced Light Source, Lawrence Berkeley National Laboratory; Yashchuk, Valeriy V.; Church, Matthew N.

2008-09-08

We review the development at the Advanced Light Source (ALS) of bendable x-ray optics widely used for focusing of beams of soft and hard x-rays. Typically, the focusing is divided in the tangential and sagittal directions into two elliptically cylindrical reflecting elements, the so-called Kirkpatrick-Baez (KB) pair [1]. Because fabrication of elliptical surfaces is complicated, the cost of directly fabricated tangential elliptical cylinders is often prohibitive. This is in contrast to flat optics, that are simpler to manufacture and easier to measure by conventional interferometry. The figure of a flat substrate can be changed by placing torques (couples) at eachmore » end. Equal couples form a tangential cylinder, and unequal couples can approximate a tangential ellipse or parabola. We review the nature of the bending, requirements and approaches to the mechanical design, and describe a technique developed at the ALS Optical Metrology Laboratory (OML) for optimal tuning of bendable mirrors before installation in the beamline [2]. The tuning technique adapts a method previously used to adjust bendable mirrors on synchrotron radiation beamlines [3]. However, in our case, optimal tuning of a bendable mirror is based on surface slope trace data obtained with a slope measuring instrument--in our case, the long trace profiler (LTP). We show that due to the near linearity of the bending problem, the minimal set of data, necessary for tuning of two benders, consists of only three slope traces measured before and after a single adjustment of each bending couple. We provide an algorithm that was used in dedicated software for finding optimal settings for the mirror benders. The algorithm is based on the method of regression analysis with experimentally found characteristic functions of the benders. The resulting approximation to the functional dependence of the desired slope shape provides nearly final settings for the benders. Moreover, the characteristic functions of the benders found in the course of tuning, can be used for retuning of the optics to a new desired shape without removing it from the beamline and re-measuring with the LTP. The result of practical use of the developed technique to precisely tune a KB mirror used at the ALS for micro-focusing is also presented. We also describe a simple ray trace using the profiler data which shows expected performance in the beamline and compare the simulation with experimental data. In summary, we also discuss the next steps in the systematic improvement of optical performance for the application of KB pairs in synchrotron beamlines at the ALS.« less

Reduced self-regulation mirrors the distorting effects of burnout symptomatology on task difficulty perception during an inhibition task.

PubMed

Wekenborg, Magdalena Katharina; Hill, LaBarron K; Miller, Robert; Stalder, Tobias; Thayer, Julian Francis; Sophie Penz, Marlene; Kirschbaum, Clemens

2018-06-09

Burnout, a pathological consequence of chronic work stress, shows an increasing incidence rate in industrialized countries. Previous findings indicate that burnout may be linked to a detachment of the negative association between subjectively appraised task demand and cognitive performance, which is typically seen in healthy individuals. The present study sought to confirm this relationship and to investigate whether this dissociation is mirrored in a biological marker of self-regulation, i.e., resting vagally mediated heart rate variability (HRV). A heterogeneous sample (N = 65) of working adults (M age = 43.3, SD = 10; 23.1 % male) with varying degrees of burnout symptomatology completed three cognitive tasks (2-back, number-letter, and go/nogo) to assess different domains of executive functioning (updating, set-shifting, and inhibition), and respective demand ratings. Additionally, vagally mediated HRV at rest, operationalized as the root-mean square differences of successive R-R intervals (RMSSD), was recorded. Burnout symptomatology moderated the association between subjective task difficulty and performance parameters of the go/nogo task, such that higher burnout scores were associated with reductions in the naturally occurring negative association between self-rated task demand and response inhibition. Intriguingly, this pattern was mirrored when replacing burnout with HRV. These findings suggest that burnout symptomatology, and individual differences in self-regulatory capacities (indexed by resting HRV), may alter one's capacity for accurate task evaluation, a mechanism which could potentially underlie the dissociation between self-rated cognitive function and actual performance among individuals experiencing burnout.

Optomechanical design software for segmented mirrors

NASA Astrophysics Data System (ADS)

Marrero, Juan

2016-08-01

The software package presented in this paper, still under development, was born to help analyzing the influence of the many parameters involved in the design of a large segmented mirror telescope. In summary, it is a set of tools which were added to a common framework as they were needed. Great emphasis has been made on the graphical presentation, as scientific visualization nowadays cannot be conceived without the use of a helpful 3d environment, showing the analyzed system as close to reality as possible. Use of third party software packages is limited to ANSYS, which should be available in the system only if the FEM results are needed. Among the various functionalities of the software, the next ones are worth mentioning here: automatic 3d model construction of a segmented mirror from a set of parameters, geometric ray tracing, automatic 3d model construction of a telescope structure around the defined mirrors from a set of parameters, segmented mirror human access assessment, analysis of integration tolerances, assessment of segments collision, structural deformation under gravity and thermal variation, mirror support system analysis including warping harness mechanisms, etc.

Titrating decision processes in the mental rotation task.

PubMed

Provost, Alexander; Heathcote, Andrew

2015-10-01

Shepard and Metzler's (1971) seminal mental-rotation task-which requires participants to decide if 1 object is a rotated version of another or its mirror image-has played a central role in the study of spatial cognition. We provide the first quantitative model of behavior in this task that is comprehensive in the sense of simultaneously providing an account of both error rates and the full distribution of response times. We used Brown and Heathcote's (2008) model of choice processing to separate out the contributions of mental rotation and decision stages. This model-based titration process was applied to data from a paradigm where converging evidence supported performance being based on rotation rather than other strategies. Stimuli were similar to Shepard and Metzler's block figures except a long major axis made rotation angle well defined for mirror stimuli, enabling comprehensive modeling of both mirror and normal responses. Results supported a mental rotation stage based on Larsen's (2014) model, where rotation takes a variable amount of time with a mean and variance that increase linearly with rotation angle. Differences in response threshold differences were largely responsible for mirror responses being slowed, and for errors increasing with rotation angle for some participants. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Interaction between vibration-evoked proprioceptive illusions and mirror-evoked visual illusions in an arm-matching task.

PubMed

Tsuge, Mikio; Izumizaki, Masahiko; Kigawa, Kazuyoshi; Atsumi, Takashi; Homma, Ikuo

2012-12-01

We studied the influence of false proprioceptive information generated by arm vibration and false visual information provided by a mirror in which subjects saw a reflection of another arm on perception of arm position, in a forearm position-matching task in right-handed subjects (n = 17). The mirror was placed between left and right arms, and arranged so that the reflected left arm appeared to the subjects to be their unseen right (reference) arm. The felt position of the right arm, indicated with a paddle, was influenced by vision of the mirror image of the left arm. If the left arm appeared flexed in the mirror, subjects felt their right arm to be more flexed than it was. Conversely, if the left arm was extended, they felt their right arm to be more extended than it was. When reference elbow flexors were vibrated at 70-80 Hz, an illusion of extension of the vibrated arm was elicited. The illusion of a more flexed reference arm evoked by seeing a mirror image of the flexed left arm was reduced by vibration. However, the illusion of extension of the right arm evoked by seeing a mirror image of the extended left arm was increased by vibration. That is, when the mirror and vibration illusions were in the same direction, they reinforced each other. However, when they were in opposite directions, they tended to cancel one another. The present study shows the interaction between proprioceptive and visual information in perception of arm position.

Direct and Conceptual Replications of Burgmer & Englich (2012): Power May Have Little to No Effect on Motor Performance

PubMed Central

Gottschalk, Christopher; Calin-Jageman, Robert J.

2015-01-01

Burgmer and Englich (2012) have reported that manipulating feelings of power can substantially improve performance on two motor tasks: golf and darts. We conducted two high-powered direct replications of the effects of power on golf, two online conceptual replications using mirror-tracing as a performance measure, and an additional conceptual replication using a cognitive performance measure (word-search). Overall, we found little to no effect of power on motor skill (d = 0.09, 95% CI[-0.07, 0.22], n = 603). We varied task difficulty, re-analyzed data without participants showing weak responses on manipulation checks, and tried adjusting performance scores for age, gender, and initial task skill. None of these secondary analyses revealed a strong effect of power on performance. A meta-analysis integrating our data with Burgmer & Englich leaves open the possibility that manipulating power could provide a modest boost in motor skill (d = 0.19, 95% CI [0.001, 0.38], n = 685). Unfortunately, the pattern of performance changes we observed was unrelated to group differences in perceived and rated power, suggesting that what motor effects do occur with this protocol may not be directly related to the construct of power. [Burgmer, P., &Englich, B. (2012). Bullseye!: How Power Improves Motor Performance. Social Psychological and Personality Science, 4(2), 224–232.] PMID:26536592

Thermal-mechanical behavior of high precision composite mirrors

NASA Technical Reports Server (NTRS)

Kuo, C. P.; Lou, M. C.; Rapp, D.

1993-01-01

Composite mirror panels were designed, constructed, analyzed, and tested in the framework of a NASA precision segmented reflector task. The deformations of the reflector surface during the exposure to space enviroments were predicted using a finite element model. The composite mirror panels have graphite-epoxy or graphite-cyanate facesheets, separated by an aluminum or a composite honeycomb core. It is pointed out that in order to carry out detailed modeling of composite mirrors with high accuracy, it is necessary to have temperature dependent properties of the materials involved and the type and magnitude of manufacturing errors and material nonuniformities. The structural modeling and analysis efforts addressed the impact of key design and materials parameters on the performance of mirrors.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Fabry—Perot interferometer with resonant mirrors

NASA Astrophysics Data System (ADS)

Troitskii, Yu V.

1995-06-01

An analysis is made of the task of construction of an interferometer with an output signal weakly dependent on the frequency of the incident light and yet highly sensitive to a change in the distance between the mirrors. This can be achieved by the use of resonant dielectric mirrors with the reflection phase and amplitude strongly dependent on the frequency within the width of the response function of the interferometer. The interferometer can be reduced to a four-mirror configuration in the case of the proposed types of mirrors. The relevant expressions are derived for this configuration. It is shown that the distance between the mirrors can be considerably greater than has been assumed earlier. A system of parameters is introduced and specific examples are considered.

REDSoX: Monte-Carlo ray-tracing for a soft x-ray spectroscopy polarimeter

NASA Astrophysics Data System (ADS)

Günther, Hans M.; Egan, Mark; Heilmann, Ralf K.; Heine, Sarah N. T.; Hellickson, Tim; Frost, Jason; Marshall, Herman L.; Schulz, Norbert S.; Theriault-Shay, Adam

2017-08-01

X-ray polarimetry offers a new window into the high-energy universe, yet there has been no instrument so far that could measure the polarization of soft X-rays (about 17-80 Å) from astrophysical sources. The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX Polarimeter) is a proposed sounding rocket experiment that uses a focusing optic and splits the beam into three channels. Each channel has a set of criticalangle transmission (CAT) gratings that disperse the x-rays onto a laterally graded multilayer (LGML) mirror, which preferentially reflects photons with a specific polarization angle. The three channels are oriented at 120 deg to each other and thus measure the three Stokes parameters: I, Q, and U. The period of the LGML changes with position. The main design challenge is to arrange the gratings so that they disperse the spectrum in such a way that all rays are dispersed onto the position on the multi-layer mirror where they satisfy the local Bragg condition despite arriving on the mirror at different angles due to the converging beam from the focusing optics. We present a polarimeteric Monte-Carlo ray-trace of this design to assess non-ideal effects from e.g. mirror scattering or the finite size of the grating facets. With mirror properties both simulated and measured in the lab for LGML mirrors of 80-200 layers we show that the reflectivity and the width of the Bragg-peak are sufficient to make this design work when non-ideal effects are included in the simulation. Our simulations give us an effective area curve, the modulation factor and the figure of merit for the REDSoX polarimeter. As an example, we simulate an observation of Mk 421 and show that we could easily detect a 20% linear polarization.

Effect of task-based mirror therapy on motor recovery of the upper extremity in chronic stroke patients: a pilot study.

PubMed

Arya, Kamal Narayan; Pandian, Shanta

2013-01-01

Mirror therapy (MT) is an alternative therapeutic intervention that uses the interaction of visuomotor-proprioception inputs to enhance movement performance of the impaired limb. Despite strong evidence for task-specific training in stroke, MT has been investigated using nontask movements. The aim of this pilot study was to assess the effectiveness of task-based MT on motor recovery of the upper extremity in chronic stroke patients. In a pretest-posttest single-group design, a convenience sample of 13 chronic stroke patients at an occupational therapy department of a rehabilitation institute was assessed on a task-based MT intervention. Participants received a task-based MT program, performing various tasks by the less affected upper extremity and observing in the mirror box along with conventional management, 4 days per week for 4 weeks. Fugl-Meyer Assessment (FMA), which includes subsection upper extremity (FMA-UE) and subpart upper arm (FMA-UA) and hand (FMA-WH), was used as an outcome measure. Participants showed no significant improvement for FMA-UE and FMA-UA at postassessment. FMA-UE changed from 43% to 51%. Post FMA-UA score showed only 2% improvement. However, there was statistically significant improvement on mean scores of FMA-WH at postassessment (16.21 ± 3.06) as compared with the prescores (12.29 ± 3.1; P < .05). FMA-WH improved from 41% to 54%. The preliminary findings suggest that task-based MT is effective in improving wrist and hand motor recovery in chronic stroke patients. Further studies in the form of randomized trials are needed to validate its effectiveness.

AXAF-1 high-resolution mirror assembly image model and comparison with x-ray ground-test image

NASA Astrophysics Data System (ADS)

Zissa, David E.

1999-09-01

The completed High Resolution Mirror Assembly (HRMA) of the Advanced X-ray Astrophysics Facility - Imaging (AXAF-I) was tested at the X-ray Calibration Facility (XRCF) at the NASA- Marshall Space Flight Center (MSFC) in 1997. The MSFC image model was developed during the development of AXAF-I. The MSFC model is a detailed ray-trace model of the as-built HRMA optics and the XRCF teste conditions. The image encircled-energy distributions from the model are found to general agree well with XRCF test data nd the preliminary Smithsonian Astrophysical Observatory (SAO) model. MSFC model effective-area result generally agree with those of the preliminary SAO model. Preliminary model effective-area results were reported by SAO to be approximately 5-13 percent above initial XRCF test results. The XRCF test conditions are removed from the MSFC ray-trace model to derive an on-orbit prediction of the HRMA image.

Neural Basis of Action Understanding: Evidence from Sign Language Aphasia.

PubMed

Rogalsky, Corianne; Raphel, Kristin; Tomkovicz, Vivian; O'Grady, Lucinda; Damasio, Hanna; Bellugi, Ursula; Hickok, Gregory

2013-01-01

The neural basis of action understanding is a hotly debated issue. The mirror neuron account holds that motor simulation in fronto-parietal circuits is critical to action understanding including speech comprehension, while others emphasize the ventral stream in the temporal lobe. Evidence from speech strongly supports the ventral stream account, but on the other hand, evidence from manual gesture comprehension (e.g., in limb apraxia) has led to contradictory findings. Here we present a lesion analysis of sign language comprehension. Sign language is an excellent model for studying mirror system function in that it bridges the gap between the visual-manual system in which mirror neurons are best characterized and language systems which have represented a theoretical target of mirror neuron research. Twenty-one life long deaf signers with focal cortical lesions performed two tasks: one involving the comprehension of individual signs and the other involving comprehension of signed sentences (commands). Participants' lesions, as indicated on MRI or CT scans, were mapped onto a template brain to explore the relationship between lesion location and sign comprehension measures. Single sign comprehension was not significantly affected by left hemisphere damage. Sentence sign comprehension impairments were associated with left temporal-parietal damage. We found that damage to mirror system related regions in the left frontal lobe were not associated with deficits on either of these comprehension tasks. We conclude that the mirror system is not critically involved in action understanding.

Advanced flow-polishing and surface metrology of the SO56 X Ray Telescope

NASA Technical Reports Server (NTRS)

1992-01-01

The surface finishing of X ray grazing incidence optics is a most demanding area of optical processing, both in terms of metrology and application of optical finishing techniques. An existing optical mirror was processed using a new removal technique that uses a jet of finely dispersed and extremely small particles that impact a surface, which under the correct conditions, produces an ultrasmooth surface, especially on aspheric curvatures. The surfaces of the SO56 mirror are tapered conical shapes that have a continuously changing radius with the primary mirror having a parabolic shape and the secondary mirror a hyperbolic shape. An optical ray trace that was conducted of a telescope used the measured parameters from the existing substrates to set up the prescription for the optical layout. The optimization indicated a wavefront performance of 0.10 A at 0.633 micron.

Thin Shell, Segmented X-Ray Mirrors

NASA Technical Reports Server (NTRS)

Petre, Robert

2010-01-01

Thin foil mirrors were introduced as a means of achieving high throughput in an X-ray astronomical imaging system in applications for which high angular resolution were not necessary. Since their introduction, their high filling factor, modest mass, relative ease of construction, and modest cost have led to their use in numerous X-ray observatories, including the Broad Band X-ray Telescope, ASCA, and Suzaku. The introduction of key innovations, including epoxy replicated surfaces, multilayer coatings, and glass mirror substrates, has led to performance improvements, and in their becoming widely used for X-ray astronomical imaging at energies above 10 keV. The use of glass substrates has also led to substantial improvement in angular resolution, and thus their incorporation into the NASA concept for the International X-ray Observatory with a planned 3 in diameter aperture. This paper traces the development of foil mirrors from their inception in the 1970's through their current and anticipated future applications.

Relationship of college student characteristics and inquiry-based geometrical optics instruction to knowledge of image formation with light-ray tracing

NASA Astrophysics Data System (ADS)

Isik, Hakan

This study is premised on the fact that student conceptions of optics appear to be unrelated to student characteristics of gender, age, years since high school graduation, or previous academic experiences. This study investigated the relationships between student characteristics and student performance on image formation test items and the changes in student conceptions of optics after an introductory inquiry-based physics course. Data was collected from 39 college students who were involved in an inquiry-based physics course teaching topics of geometrical optics. Student data concerning characteristics and previous experiences with optics and mathematics were collected. Assessment of student understanding of optics knowledge for pinholes, plane mirrors, refraction, and convex lenses was collected with, the Test of Image Formation with Light-Ray Tracing instrument. Total scale and subscale scores representing the optics instrument content were derived from student pretest and posttest responses. The types of knowledge, needed to answer each optics item correctly, were categorized as situational, conceptual, procedural, and strategic knowledge. These types of knowledge were associated with student correct and incorrect responses to each item to explain the existences and changes in student scientific and naive conceptions. Correlation and stepwise multiple regression analyses were conducted to identify the student characteristics and academic experiences that significantly predicted scores on the subscales of the test. The results showed that student experience with calculus was a significant predictor of student performance on the total scale as well as on the refraction subscale of the Test of Image Formation with Light-Ray Tracing. A combination of student age and previous academic experience with precalculus was a significant predictor of student performance on the pretest pinhole subscale. Student characteristic of years since high school graduation significantly predicted the gain in student scores on pinhole and plane-mirror items from the pretest to the posttest with those students who were most recent graduates from high school doing better. Multivariate and univariate analyses of variance of the Test of Image Formation with Light-Ray Tracing pinhole scale and individual item changes from the pretest to the posttest resulted in statistically significant mean differences between total scores as well as between various individual pinhole items. There were no significant changes for individual plane-mirror items from pretest to posttest. Results revealed that there is a perceivable relationship between student optics-content knowledge and the types of knowledge required by items. At the pretest, the greatest selection of wrong responses related to the items requiring situational type of knowledge and the fewest selection of wrong responses was relate to the items requiring procedural type of knowledge. Student selection of wrong options for each item revealed the following naive optics conceptions: pinholes do not create reversed images (pretest), size and sharpness of pinhole images are related to the focus of a pinhole camera (pretest and posttest); propagation of light rays are interpreted as being radial rather than directional (pretest and posttest); no conception of image formation and observation for parallel mirrors (pretest and posttest), the place of an image depends on the position of the observer (pretest and posttest), a plane mirror reflects the images of the objects placed at one side of the mirror and the observers who were positioned at the other side of the mirror can see them (pretest and posttest); applying the law of reflection to plane mirrors without considering the variations in angles of incidence and reflection (pretest and posttest), and image observation is confused with the image formation in mirrors placed perpendicular to one another (pretest and posttest). Future research should focus on the acquisition, development, and identification of reliable measures of optics concepts, processes, types of knowledge, and specific optics understanding (i.e., pinhole, plane-mirror). Future research should focus on the identification of the more critical concepts such as changes in size and sharpness of pinhole images, image observation, image formation in general, and image formation and observation in parallel mirrors. Future research can be conducted with a larger set of participants so as to compare different instructional methods and address instructional deficiencies using more efficient statistical methods. Comparative studies can be conducted to investigate the relations of various instructional strategies on student conceptions of optics.

Assessment of Self-Recognition in Young Children with Handicaps.

ERIC Educational Resources Information Center

Kelley, Michael F.; And Others

1988-01-01

Thirty young children with handicaps were assessed on five self-recognition mirror tasks. The set of tasks formed a reproducible scale, indicating that these tasks are an appropriate measure of self-recognition in this population. Data analysis suggested that stage of self-recognition is positively and significantly related to cognitive…

Interference testing methods of large astronomical mirrors base on lenses and CGH wavefront correctors

NASA Astrophysics Data System (ADS)

Abdulkadyrov, Magomed A.; Belousov, Sergey P.; Patrikeev, Vladimir E.; Semenov, Alexandr P.

2010-07-01

Since last years and at present days LZOS, JSC has been producing a range of primary mirrors of astronomical telescopes with diameter more than 1m under contracts with foreign companies. Simultaneous testing of an aspherical surface figure by means of a lens corrector and CGH (computer generated hologram) corrector, testing of the corrector using the CGH allow challenging the task of definite testing of the mirrors surfaces figure. The results of successful figuring of the mirrors with diameter up to 4m like VISTA Project (Southern European Observatory), TNT (Thai National telescope, Australia - Thailand), LCO telescopes (Las Cumbres Observatory, USA; Russian national projects and meeting these mirrors specifications' requirements are all considered as the sufficient evidence.

An augmented reality home-training system based on the mirror training and imagery approach.

PubMed

Trojan, Jörg; Diers, Martin; Fuchs, Xaver; Bach, Felix; Bekrater-Bodmann, Robin; Foell, Jens; Kamping, Sandra; Rance, Mariela; Maaß, Heiko; Flor, Herta

2014-09-01

Mirror training and movement imagery have been demonstrated to be effective in treating several clinical conditions, such as phantom limb pain, stroke-induced hemiparesis, and complex regional pain syndrome. This article presents an augmented reality home-training system based on the mirror and imagery treatment approaches for hand training. A head-mounted display equipped with cameras captures one hand held in front of the body, mirrors this hand, and displays it in real time in a set of four different training tasks: (1) flexing fingers in a predefined sequence, (2) moving the hand into a posture fitting into a silhouette template, (3) driving a "Snake" video game with the index finger, and (4) grasping and moving a virtual ball. The system records task performance and transfers these data to a central server via the Internet, allowing monitoring of training progress. We evaluated the system by having 7 healthy participants train with it over the course of ten sessions of 15-min duration. No technical problems emerged during this time. Performance indicators showed that the system achieves a good balance between relatively easy and more challenging tasks and that participants improved significantly over the training sessions. This suggests that the system is well suited to maintain motivation in patients, especially when it is used for a prolonged period of time.

Inadvertent recovery in communication deficits following the upper limb mirror therapy in stroke: A case report.

PubMed

Arya, Kamal Narayan; Pandian, Shanta

2014-10-01

Broca's aphasia is the most challenging communication deficit in stroke. Left inferior frontal gyrus (IFG), a key region of the mirror-neuron system, gets lesioned in Broca's aphasia. Mirror therapy (MT), a form of action-observation, may trigger the mirror neurons. The aim of this study was to report a case of poststroke subject with Broca's aphasia, who exhibited an inadvertent and significant improvement in speech after MT for the paretic upper limb. The 20-month old stroke patient underwent MT through goal-directed tasks. He received a total absence of spontaneous speech, writing, and naming. After 45 sessions of task-based MT for the upper limb, he showed tremendous recovery in expressive communication. He had fluent and comprehensive communication; however, with a low pitch and minor pronunciation errors. He showed a substantial change (from 18/100 to 79/100) on the Communicative Effective Index, particularly, on items such as expressing emotions, one-to-one conversation, naming, and spontaneous conversation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Design and research of built-in sample cell with multiple optical reflections

NASA Astrophysics Data System (ADS)

Liu, Jianhui; Wang, Shuyao; Lv, Jinwei; Liu, Shuyang; Zhou, Tao; Jia, Xiaodong

2017-10-01

In the field of trace gas measurement, with the characteristics of high sensitivity, high selectivity and rapid detection, tunable diode laser absorption spectroscopy (TDLAS) is widely used in industrial process and trace gas pollution monitoring. Herriott cell is a common form of multiple reflections of the sample cell, the structure of the Herriott cell is relatively simple, which be used to application of trace gas absorption spectroscopy. In the pragmatic situation, the gas components are complicated, and the continuous testing process for a long time can lead to different degree of pollution and corrosion for the reflector in the sample cell. If the mirror is not cleaned up in time, it will have a great influence on the detection accuracy. In order to solve this problem in the process of harsh environment detection, this paper presents a design of the built-in sample cell to avoid the contact of gas and the mirror, thereby effectively reducing corrosion pollution. If there is optical pollution, direct replacement of the built-in optical sample cell can easily to be disassembled, and cleaned. The advantage of this design is long optical path, high precision, cost savings and so on.

Measuring a Precise Ultra-Lightweight Spaceflight Mirror on Earth: The Analysis of the SHARPI PM Mirror Figure Data during Mirror Processing at GSFC

NASA Technical Reports Server (NTRS)

Antonille, Scott; Content, David; Rabin, Douglas; Wallace, Thomas; Wake, Shane

2007-01-01

The SHARPI (Solar High Angular Resolution Photometric Imager) primary mirror is a 5kg, 0.5m paraboloid, diffraction limited at FUV wavelengths when placed in a 0-G environment. The ULE sandwich honeycomb mirror and the attached mount pads were delivered by ITT (then Kodak) in 2003 to NASA s Goddard Space Flight Center (GSFC). At GSFC, we accepted, coated, mounted, and vibration tested this mirror in preparation for flight on the PICTURES (Planet Imaging Concept Testbed Using a Rocket Experiment) mission. At each step, the integrated analysis of interferometer data and FEA models was essential to quantify the 0-G mirror figure. This task required separating nanometer sized variations from hundreds of nanometers of gravity induced distortion. The ability to isolate such features allowed in-situ monitoring of mirror figure, diagnosis of perturbations, and remediation of process errors. In this paper, we describe the technical approach used to achieve these measurements and overcome the various difficulties maintaining UV diffraction-limited performance with this aggressively lightweighted mirror.

Replicated Composite Optics Development

NASA Technical Reports Server (NTRS)

Engelhaupt, Darell

1997-01-01

Advanced optical systems for applications such as grazing incidence Wolter I x-ray mirror assemblies require extraordinary mirror surfaces in ten-ns of fine surface finish and figure. The impeccable mirror surface is on the inside of the rotational mirror form. One practical method of producing devices with these requirements is to first fabricate an exterior surface for the optical device then replicate that surface to have the inverse component with lightweight characteristics. The replicate optic is not better than the master or mandrel from which it is made. This task is a continuance of previous studies to identify methods and materials for forming these extremely low roughness optical components.

A Mirror Therapy-Based Action Observation Protocol to Improve Motor Learning After Stroke.

PubMed

Harmsen, Wouter J; Bussmann, Johannes B J; Selles, Ruud W; Hurkmans, Henri L P; Ribbers, Gerard M

2015-07-01

Mirror therapy is a priming technique to improve motor function of the affected arm after stroke. To investigate whether a mirror therapy-based action observation (AO) protocol contributes to motor learning of the affected arm after stroke. A total of 37 participants in the chronic stage after stroke were randomly allocated to the AO or control observation (CO) group. Participants were instructed to perform an upper-arm reaching task as fast and as fluently as possible. All participants trained the upper-arm reaching task with their affected arm alternated with either AO or CO. Participants in the AO group observed mirrored video tapes of reaching movements performed by their unaffected arm, whereas participants in the CO group observed static photographs of landscapes. The experimental condition effect was investigated by evaluating the primary outcome measure: movement time (in seconds) of the reaching movement, measured by accelerometry. Movement time decreased significantly in both groups: 18.3% in the AO and 9.1% in the CO group. Decrease in movement time was significantly more in the AO compared with the CO group (mean difference = 0.14 s; 95% confidence interval = 0.02, 0.26; P = .026). The present study showed that a mirror therapy-based AO protocol contributes to motor learning after stroke. © The Author(s) 2014.

Astigmatism-free Czerny-Turner compact spectrometer with cylindrical mirrors.

PubMed

Xia, Guo; Wu, Su; Wang, Guodong; Hu, Mingyong; Xing, Jinyu

2017-11-10

A modified optical design for a broadband, high resolution, astigmatism-free Czerny-Turner spectrometer is proposed. Astigmatism is corrected by using cylindrical mirrors over a broad spectral range. The theory and method for astigmatism correction are thoroughly analyzed. The comparison between the modified Czerny-Turner spectrometer and the traditional Czerny-Turner spectrometer is also described in detail. The ray-tracing results show that the RMS spot radius has decreased to 4.2 μm at the central wavelength and 17 μm at the wedge wavelength.

Some Informal Thoughts on Relativity and Limitations on Interstellar Travel

DTIC Science & Technology

1990-12-01

velocities, as quantified by the following: Consider a device made up of a light source, a light detector, and a mirror in the following relationship (after...the source and detector are close enough together so that the value of the cosine of the angle of incidence on the mirror can be taken to be 1, a light ...34 observer will see the light pulse trace a diagonal path with length 2 z4 + (vAt/2)2 at a speed (by Postulate 2) of c. The duration of a transit measured

The Effects of Mirror Feedback during Target Directed Movements on Ipsilateral Corticospinal Excitability

PubMed Central

Yarossi, Mathew; Manuweera, Thushini; Adamovich, Sergei V.; Tunik, Eugene

2017-01-01

Mirror visual feedback (MVF) training is a promising technique to promote activation in the lesioned hemisphere following stroke, and aid recovery. However, current outcomes of MVF training are mixed, in part, due to variability in the task undertaken during MVF. The present study investigated the hypothesis that movements directed toward visual targets may enhance MVF modulation of motor cortex (M1) excitability ipsilateral to the trained hand compared to movements without visual targets. Ten healthy subjects participated in a 2 × 2 factorial design in which feedback (veridical, mirror) and presence of a visual target (target present, target absent) for a right index-finger flexion task were systematically manipulated in a virtual environment. To measure M1 excitability, transcranial magnetic stimulation (TMS) was applied to the hemisphere ipsilateral to the trained hand to elicit motor evoked potentials (MEPs) in the untrained first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles at rest prior to and following each of four 2-min blocks of 30 movements (B1–B4). Targeted movement kinematics without visual feedback was measured before and after training to assess learning and transfer. FDI MEPs were decreased in B1 and B2 when movements were made with veridical feedback and visual targets were absent. FDI MEPs were decreased in B2 and B3 when movements were made with mirror feedback and visual targets were absent. FDI MEPs were increased in B3 when movements were made with mirror feedback and visual targets were present. Significant MEP changes were not present for the uninvolved ADM, suggesting a task-specific effect. Analysis of kinematics revealed learning occurred in visual target-directed conditions, but transfer was not sensitive to mirror feedback. Results are discussed with respect to current theoretical mechanisms underlying MVF-induced changes in ipsilateral excitability. PMID:28553218

Graded Mirror Self-Recognition by Clark's Nutcrackers.

PubMed

Clary, Dawson; Kelly, Debbie M

2016-11-04

The traditional 'mark test' has shown some large-brained species are capable of mirror self-recognition. During this test a mark is inconspicuously placed on an animal's body where it can only be seen with the aid of a mirror. If the animal increases the number of actions directed to the mark region when presented with a mirror, the animal is presumed to have recognized the mirror image as its reflection. However, the pass/fail nature of the mark test presupposes self-recognition exists in entirety or not at all. We developed a novel mirror-recognition task, to supplement the mark test, which revealed gradation in the self-recognition of Clark's nutcrackers, a large-brained corvid. To do so, nutcrackers cached food alone, observed by another nutcracker, or with a regular or blurry mirror. The nutcrackers suppressed caching with a regular mirror, a behavioural response to prevent cache theft by conspecifics, but did not suppress caching with a blurry mirror. Likewise, during the mark test, most nutcrackers made more self-directed actions to the mark with a blurry mirror than a regular mirror. Both results suggest self-recognition was more readily achieved with the blurry mirror and that self-recognition may be more broadly present among animals than currently thought.

Sex differences in mental rotation tasks: Not just in the mental rotation process!

PubMed

Boone, Alexander P; Hegarty, Mary

2017-07-01

The paper-and-pencil Mental Rotation Test (Vandenberg & Kuse, 1978) consistently produces large sex differences favoring men (Voyer, Voyer, & Bryden, 1995). In this task, participants select 2 of 4 answer choices that are rotations of a probe stimulus. Incorrect choices (i.e., foils) are either mirror reflections of the probe or structurally different. In contrast, in the mental rotation experimental task (Shepard & Metzler, 1971) participants judge whether 2 stimuli are the same but rotated or different by mirror reflection. The goal of the present research was to examine sources of sex differences in mental rotation, including the ability to capitalize on the availability of structure foils. In 2 experiments, both men and women had greater accuracy and faster reaction times (RTs) for structurally different compared with mirror foils in different versions of the Vandenberg and Kuse Mental Rotation Test (Experiment 1) and the Shepard and Metzler experimental task (Experiment 2). A significant male advantage in accuracy but not response time was found for both trial types. The male advantage was evident when all foils were structure foils so that mental rotation was not necessary (Experiment 3); however, when all foils were structure foils and participants were instructed to look for structure foils a significant sex difference was no longer evident (Experiment 4). Results suggest that the mental rotation process is not the only source of the sex difference in mental rotation tasks. Alternative strategy use is another source of sex differences in these tasks. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Wave-optical assessment of alignment tolerances in nano-focusing with ellipsoidal mirror

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

Yumoto, Hirokatsu, E-mail: yumoto@spring8.or.jp; Koyama, Takahisa; Matsuyama, Satoshi

2016-01-28

High-precision ellipsoidal mirrors, which can efficiently focus X-rays to the nanometer dimension with a mirror, have not been realized because of the difficulties in the fabrication process. The purpose of our study was to develop nano-focusing ellipsoidal mirrors in the hard X-ray region. We developed a wave-optical focusing simulator for investigating alignment tolerances in nano-focusing with a designed ellipsoidal mirror, which produce a diffraction-limited focus size of 30 × 35 nm{sup 2} in full width at half maximum at an X-ray energy of 7 keV. The simulator can calculate focusing intensity distributions around the focal point under conditions of misalignment. Themore » wave-optical simulator enabled the calculation of interference intensity distributions, which cannot be predicted by the conventional ray-trace method. The alignment conditions with a focal length error of ≲ ±10 µm, incident angle error of ≲ ±0.5 µrad, and in-plane rotation angle error of ≲ ±0.25 µrad must be satisfied for nano-focusing.« less

Interactive visuo-motor therapy system for stroke rehabilitation.

PubMed

Eng, Kynan; Siekierka, Ewa; Pyk, Pawel; Chevrier, Edith; Hauser, Yves; Cameirao, Monica; Holper, Lisa; Hägni, Karin; Zimmerli, Lukas; Duff, Armin; Schuster, Corina; Bassetti, Claudio; Verschure, Paul; Kiper, Daniel

2007-09-01

We present a virtual reality (VR)-based motor neurorehabilitation system for stroke patients with upper limb paresis. It is based on two hypotheses: (1) observed actions correlated with self-generated or intended actions engage cortical motor observation, planning and execution areas ("mirror neurons"); (2) activation in damaged parts of motor cortex can be enhanced by viewing mirrored movements of non-paretic limbs. We postulate that our approach, applied during the acute post-stroke phase, facilitates motor re-learning and improves functional recovery. The patient controls a first-person view of virtual arms in tasks varying from simple (hitting objects) to complex (grasping and moving objects). The therapist adjusts weighting factors in the non-paretic limb to move the paretic virtual limb, thereby stimulating the mirror neuron system and optimizing patient motivation through graded task success. We present the system's neuroscientific background, technical details and preliminary results.

Laparoscopic skills training using a webcam trainer.

PubMed

Chung, Steve Y; Landsittel, Douglas; Chon, Chris H; Ng, Christopher S; Fuchs, Gerhard J

2005-01-01

Many sophisticated and expensive trainers have been developed to assist surgeons in learning basic laparoscopic skills. We developed an inexpensive trainer and evaluated its effectiveness. The webcam laparoscopic training device is composed of a webcam, cardboard box, desk lamp and home computer. This homemade trainer was evaluated against 2 commercially available systems, namely the video Pelvitrainer (Karl Storz Endoscopy, Culver City, California) and the dual mirror Simuview (Simulab Corp., Seattle, Washington). The Pelvitrainer consists of a fiberglass box, single lens optic laparoscope, fiberoptic light source, endoscopic camera and video monitor, while the Simuview trainer uses 2 offset, facing mirrors and an uncovered plastic box. A total of 42 participants without prior laparoscopic training were enrolled in the study and asked to execute 2 tasks, that is peg transfer and pattern cutting. Participants were randomly assigned to 6 groups with each group representing a different permutation of trainers to be used. The time required for participants to complete each task was recorded and differences in performance were calculated. Paired t tests, the Wilcoxon signed rank test and ANOVA were performed to analyze the statistical difference in performance times for all conditions. Statistical analyses of the 2 tasks showed no significant difference for the video and webcam trainers. However, the mirror trainer gave significantly higher outcome values for tasks 1 and 2 compared to the video (p = 0.01 and <0.01) and webcam (p = 0.04 and <0.01, respectively) methods. ANOVA indicated no overall difference for tasks 1 and 2 across the orderings (p = 0.36 and 0.99, respectively). However, by attempt 3 the time required to complete the skill tests decreased significantly for all 3 trainers (each p <0.01). Our homemade webcam system is comparable in function to the more elaborate video trainer but superior to the dual mirror trainer. For novice laparoscopists we believe that the webcam system is an inexpensive and effective laparoscopic training device. Furthermore, the webcam system also allows instant recording and review of techniques.

Effects of mirror therapy integrated with task-oriented exercise on the balance function of patients with poststroke hemiparesis: a randomized-controlled pilot trial.

PubMed

Cha, Hyun-Gyu; Oh, Duck-Won

2016-03-01

This study aimed to explore the effects of mirror therapy integrated with task-oriented exercise on balance function in poststroke hemiparesis. Twenty patients with poststroke hemiparesis were assigned randomly to an experimental group (EG) and a control group (CG), with 10 individuals each. Participants of the EG and CG received a task-oriented exercise program with a focus on the strengthening of the lower limb and the practice of balance-related functional tasks. An additional option for the EG was front and side wall mirrors to provide visual feedback for their own movements while performing the exercise. The program was performed for 30 min, twice a day, five times per week for 4 weeks. Outcome measures included the Berg balance scale, the timed up-and-go test, and quantitative data (balance index and dynamic limits of stability). In the EG and CG, all variables showed significant differences between pretest and post-test (P<0.05), and post-test values of all variables appeared to be significantly different between two groups (P<0.05). Furthermore, in the EG, the change values between pretest and post-test values of Berg balance scale (13.00±3.20 vs. 6.60±4.55 scores), and timed up-and-go test (6.45±3.00 vs. 3.61±1.84 s), balance index (2.29±0.51 vs. 0.96±0.65 scores), dynamic limits of stability (7.70±3.83 vs. 3.70±4.60 scores) were significantly higher than those of the CG (P<0.05). The findings suggest that a mirror therapy may be used as a beneficial therapeutic option to facilitate the effects of a task-oriented exercise on balance function of patients with poststroke hemiparesis.

Into the Looking Glass: Literacy Acquisition and Mirror Invariance in Preschool and First-Grade Children

ERIC Educational Resources Information Center

Fernandes, Tânia; Leite, Isabel; Kolinsky, Régine

2016-01-01

At what point in reading development does literacy impact object recognition and orientation processing? Is it specific to mirror images? To answer these questions, forty-six 5- to 7-year-old preschoolers and first graders performed two same-different tasks differing in the matching criterion-orientation-based versus shape-based (orientation…

Heightened motor and sensory (mirror-touch) referral induced by nerve block or topical anesthetic.

PubMed

Case, Laura K; Gosavi, Radhika; Ramachandran, Vilayanur S

2013-08-01

Mirror neurons allow us to covertly simulate the sensation and movement of others. If mirror neurons are sensory and motor neurons, why do we not actually feel this simulation- like "mirror-touch synesthetes"? Might afferent sensation normally inhibit mirror representations from reaching consciousness? We and others have reported heightened sensory referral to phantom limbs and temporarily anesthetized arms. These patients, however, had experienced illness or injury of the deafferented limb. In the current study we observe heightened sensory and motor referral to the face after unilateral nerve block for routine dental procedures. We also obtain double-blind, quantitative evidence of heightened sensory referral in healthy participants completing a mirror-touch confusion task after topical anesthetic cream is applied. We suggest that sensory and motor feedback exist in dynamic equilibrium with mirror representations; as feedback is reduced, the brain draws more upon visual information to determine- perhaps in a Bayesian manner- what to feel. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optical design of the ATMOS Fourier transform spectrometer

NASA Technical Reports Server (NTRS)

Abel, I. R.; Reynolds, B. R.; Breckinridge, J. B.; Pritchard, J.

1979-01-01

The optical system design of the ATMOS Fourier transform spectrometer to be operated from Spacelab for the measurement of stratospheric trace molecules is described. The design contains features which can achieve the required fringe contrast of 80% and spectral resolution of 0.02/cm over a spectral range of 2-16 microns. In particular, the design is based on the following features which alleviate the usual requirements for alignment precision: (1) 'cat's eye' mirror configuration in the two arms of the interferometer for retroreflection stability, (2) tilt-compensated system of beamsplitter, compensator, and fold mirrors for wavefront directional stability, (3) paraboloidal 'cat's eye' primary mirror for wavefront stability against shear, (4) rotatable compensator for matching chromatic dispersion, and (5) wedged refractive components to avoid channel spectra due to the Fabry-Perot effect.

Progress Report on Optimizing X-ray Optical Prescriptions for Wide-Field Applications

NASA Technical Reports Server (NTRS)

Elsner, R. F.; O'Dell, S. L.; Ramsey, B. D.; Weisskopf, M. C.

2011-01-01

We report on the present status of our continuing efforts to develop a method for optimizing wide-field nested x-ray telescope mirror prescriptions. Utilizing extensive Monte-Carlo ray trace simulations, we find an analytic form for the root-mean-square dispersion of rays from a Wolter I optic on the surface of a flat focal plane detector as a function of detector tilt away from the nominal focal plane and detector displacement along the optical axis. The configuration minimizing the ray dispersion from a nested array of Wolter I telescopes is found by solving a linear system of equations for tilt and individual mirror pair displacement. Finally we outline our initial efforts at expanding this method to include higher order polynomial terms in the mirror prescriptions.

Smooth leader or sharp follower? Playing the mirror game with a robot.

PubMed

Kashi, Shir; Levy-Tzedek, Shelly

2018-01-01

The increasing number of opportunities for human-robot interactions in various settings, from industry through home use to rehabilitation, creates a need to understand how to best personalize human-robot interactions to fit both the user and the task at hand. In the current experiment, we explored a human-robot collaborative task of joint movement, in the context of an interactive game. We set out to test people's preferences when interacting with a robotic arm, playing a leader-follower imitation game (the mirror game). Twenty two young participants played the mirror game with the robotic arm, where one player (person or robot) followed the movements of the other. Each partner (person and robot) was leading part of the time, and following part of the time. When the robotic arm was leading the joint movement, it performed movements that were either sharp or smooth, which participants were later asked to rate. The greatest preference was given to smooth movements. Half of the participants preferred to lead, and half preferred to follow. Importantly, we found that the movements of the robotic arm primed the subsequent movements performed by the participants. The priming effect by the robot on the movements of the human should be considered when designing interactions with robots. Our results demonstrate individual differences in preferences regarding the role of the human and the joint motion path of the robot and the human when performing the mirror game collaborative task, and highlight the importance of personalized human-robot interactions.

Multi-task feature learning by using trace norm regularization

NASA Astrophysics Data System (ADS)

Jiangmei, Zhang; Binfeng, Yu; Haibo, Ji; Wang, Kunpeng

2017-11-01

Multi-task learning can extract the correlation of multiple related machine learning problems to improve performance. This paper considers applying the multi-task learning method to learn a single task. We propose a new learning approach, which employs the mixture of expert model to divide a learning task into several related sub-tasks, and then uses the trace norm regularization to extract common feature representation of these sub-tasks. A nonlinear extension of this approach by using kernel is also provided. Experiments conducted on both simulated and real data sets demonstrate the advantage of the proposed approach.

Do Adults with Autism Spectrum Disorders Compensate in Naturalistic Prospective Memory Tasks?

ERIC Educational Resources Information Center

Altgassen, Mareike; Koban, Nancy; Kliegel, Matthias

2012-01-01

The present study is the first to directly compare event- and time-based prospective memory in Autism Spectrum Disorders (ASD) using a contextual task mirroring real life demands of prospective memory. Twenty-five individuals with ASD and 25 age- and ability-matched controls completed the Dresden Breakfast task which required participants to…

Task-based mirror therapy enhances ipsilesional motor functions in stroke: A pilot study.

PubMed

Arya, Kamal Narayan; Pandian, Shanta; Kumar, Dharmendra

2017-04-01

To examine the effect of Mirror therapy (MT) on dexterity, coordination, and muscle strength of the less-affected upper limb in stroke. Pre-test post-test, single group, experimental design. Rehabilitation institute. Post-stroke hemiparetic chronic subjects (N = 21). Forty sessions of MT using various tasks in addition to the conventional rehabilitation. Tasks such as lifting a glass, ball-squeezing, and picking-up objects were performed by the less-affected side in front of the mirror-box creating an illusion for the affected side. Minnesota Manual Dexterity Test (MMDT), Purdue Peg Board Test (PPBT), and Manual Muscle Testing (MMT) were used to measure the deficits of the less-affected side. Post-intervention, the less-affected side of the participants exhibited significant improvement on MMDT (p < 0.001), PPBT (p < 0.001), and MMT (shoulder flexors, wrist extensors and deviators, and finger flexors-extensors; p = 0.005-0.046). In post-stroke hemiparesis, MT also led to the improvement in dexterity, coordination, and strength of the less-affected side. In addition to the affected side, the technique may augment the subtle motor deficits of the less-affected side. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Small Module Fixed Mirror Distributed Focus (FMDF) Photothermal Concentrator Study

NASA Technical Reports Server (NTRS)

Meinel, A. B.

1981-01-01

The development of a general ray trace evaluation program called ICARUS, the study of novel Fresnel concepts, and the review of a report draft on novel Fresnel concepts are covered. ICARUS is documented, reports on the novel Fresnel concepts were previously submitted.

Different Effects of Hypoxia on Mental Rotation of Normal and Mirrored Letters: Evidence from the Rotation-Related Negativity.

PubMed

Ma, Qingguo; Hu, Linfeng; Li, Jiaojie; Hu, Yue; Xia, Ling; Chen, Xiaojian; Hu, Wendong

2016-01-01

The present study explored the neural mechanism underlying the effect of moderate and transient hypoxic exposure on mental rotation of two-dimensional letters in both normal and mirror versions. Event-related potential data and behavioral data were acquired in the task of discrimination between normal and mirrored versions separately in conditions of normoxia (simulated sea level) and hypoxia conditions (simulated 5000 meter altitude). The behavioral results revealed no significant difference between the normoxia and hypoxia conditions both in response time and error rate. However, obvious differences between these two conditions in ERP were found. First, enlarged P300 and Rotation-related Negativity (RRN) were observed in the hypoxia condition compared to the normoxia condition only with normal letters. Second, the angle effect on the amplitude of RRN was more evident with normal letters in the hypoxia condition than that in the normoxia condition. However, this angle effect nearly disappeared with the mirrored letters in the hypoxia condition. Third, more bilateral parietal activation was observed in the hypoxia condition than the normoxia condition. These results suggested that the compensation mechanism existed in the hypoxia condition and was effective with normal letters but had little effect on the mirrored letters. This study extends the research about the hypoxic effect on spatial ability of humans by employing a mental rotation task and further provides neural evidence for this effect.

Different Effects of Hypoxia on Mental Rotation of Normal and Mirrored Letters: Evidence from the Rotation-Related Negativity

PubMed Central

Ma, Qingguo; Hu, Linfeng; Li, Jiaojie; Hu, Yue; Xia, Ling; Chen, Xiaojian; Hu, Wendong

2016-01-01

The present study explored the neural mechanism underlying the effect of moderate and transient hypoxic exposure on mental rotation of two-dimensional letters in both normal and mirror versions. Event-related potential data and behavioral data were acquired in the task of discrimination between normal and mirrored versions separately in conditions of normoxia (simulated sea level) and hypoxia conditions (simulated 5000 meter altitude). The behavioral results revealed no significant difference between the normoxia and hypoxia conditions both in response time and error rate. However, obvious differences between these two conditions in ERP were found. First, enlarged P300 and Rotation-related Negativity (RRN) were observed in the hypoxia condition compared to the normoxia condition only with normal letters. Second, the angle effect on the amplitude of RRN was more evident with normal letters in the hypoxia condition than that in the normoxia condition. However, this angle effect nearly disappeared with the mirrored letters in the hypoxia condition. Third, more bilateral parietal activation was observed in the hypoxia condition than the normoxia condition. These results suggested that the compensation mechanism existed in the hypoxia condition and was effective with normal letters but had little effect on the mirrored letters. This study extends the research about the hypoxic effect on spatial ability of humans by employing a mental rotation task and further provides neural evidence for this effect. PMID:27144444

Watch Your Step Children! Learning Two-Digit Numbers through Mirror-Based Observation of Self-Initiated Body Movements

ERIC Educational Resources Information Center

Ruiter, Margina; Loyens, Sofie; Paas, Fred

2015-01-01

It was investigated whether task-related body movements yield beneficial effects on children's learning of two-digit numbers and whether these learning effects are affected by mirror-based self-observation of those movements. Participants were 118 first-graders, who were randomly assigned to two movement conditions and two non-movement control…

Training Compliance Control Yields Improvements in Drawing as a Function of Beery Scores

PubMed Central

Snapp-Childs, Winona; Flatters, Ian; Fath, Aaron; Mon-Williams, Mark; Bingham, Geoffrey P.

2014-01-01

Many children have difficulty producing movements well enough to improve in sensori-motor learning. Previously, we developed a training method that supports active movement generation to allow improvement at a 3D tracing task requiring good compliance control. Here, we tested 7–8 year old children from several 2nd grade classrooms to determine whether 3D tracing performance could be predicted using the Beery VMI. We also examined whether 3D tracing training lead to improvements in drawing. Baseline testing included Beery, a drawing task on a tablet computer, and 3D tracing. We found that baseline performance in 3D tracing and drawing co-varied with the visual perception (VP) component of the Beery. Differences in 3D tracing between children scoring low versus high on the Beery VP replicated differences previously found between children with and without motor impairments, as did post-training performance that eliminated these differences. Drawing improved as a result of training in the 3D tracing task. The training method improved drawing and reduced differences predicted by Beery scores. PMID:24651280

Persistent left unilateral mirror writing: A neuropsychological case study.

PubMed

Angelillo, Valentina G; De Lucia, Natascia; Trojano, Luigi; Grossi, Dario

2010-09-01

Mirror writing (MW) is a rare disorder in which a script runs in direction opposite to normal and individual letters are reversed. The disorder generally occurs after left-hemisphere lesions, is transient and is observed on the left hand, whereas usually motor impairments prevent assessment of direction of right handwriting. We describe a left-handed patient with complete left hand mirror writing, still evident 2 years after a hemorrhagic stroke in left nucleo-capsular region. Since the patient could write with his right hand he underwent several writing tasks with either hand, and a thorough assessment to clarify the nature of MW. MW was evident in writing to dictation with left hand only, both in right and left hemispace, but the patient could modify his behavior when a verbal instruction was provided. No mirror errors were found in reading words, in copying geometric figures and in spatial orientation tasks. MW in our patient could be accounted for by a failure in automatic transformation of grapho-motor programs to write with the left hand. A lack of concern (a sort of anosodiaphoria) and a poor cognitive flexibility could contribute to long-term persistence of MW. 2010 Elsevier Inc. All rights reserved.

Analysis Of The Boeing FEL Mirror Measurements

NASA Astrophysics Data System (ADS)

Knapp, Charles E.; Viswanathan, Vriddhachalam K.; Appert, Quentin D.

1989-07-01

The aberrations have been measured for the finished mirrors that are part of the Burst Mode ring resonator of the Free Electron Laser (FEL) being constructed at the Boeing Aerospace Company in Seattle, Washington. This paper presents analysis of these measurements using the GLAD code, a diffraction ray-tracing code. The diffraction losses within the resonator due to the aberrations are presented. The analysis was conducted in two different modes, a paraxial approximation and a full 3-D calculation, and good agreement between the two approaches is shown. Finally, a proposed solution to the problems caused by the aberrations is presented and analyzed.

Cassegrain antenna with a semitransparent secondary mirror.

PubMed

Caiyang, Weinan; Yang, Huajun; Jiang, Ping; He, Wensen; Tian, Yu; Chen, Xue

2017-06-10

With the help of the vector theory of reflection and refraction, a novel emitting Cassegrain antenna with a semitransparent secondary mirror has been proposed and analyzed for a distant point source. Based on the absorptivity valued at 3.00% and the reflectivity valued at 0.10%, this new emitting antenna can increase the transmission efficiency from 63.65% to 93.85%. In addition, an off-axis parabolic receiving antenna corresponding to the emitting antenna is designed and the 3D ray-trace simulation result is given. According to the simulation result, this receiving antenna can nicely converge the rays from the emitting antenna.

Trace Element Mapping of a Biological Specimen by a Full-Field X-ray Fluorescence Imaging Microscope with a Wolter Mirror

NASA Astrophysics Data System (ADS)

Hoshino, Masato; Yamada, Norimitsu; Ishino, Toyoaki; Namiki, Takashi; Watanabe, Norio; Aoki, Sadao

2007-01-01

A full-field X-ray fluorescence imaging microscope with a Wolter mirror was applied to the element mapping of alfalfa seeds. The X-ray fluorescence microscope was built at the Photon Factory BL3C2 (KEK). X-ray fluorescence images of several growing stages of the alfalfa seeds were obtained. X-ray fluorescence energy spectra were measured with either a solid state detector or a CCD photon counting method. The element distributions of iron and zinc which were included in the seeds were obtained using a photon counting method.

Evaluating progressive-rendering algorithms in appearance design tasks.

PubMed

Jiawei Ou; Karlik, Ondrej; Křivánek, Jaroslav; Pellacini, Fabio

2013-01-01

Progressive rendering is becoming a popular alternative to precomputational approaches to appearance design. However, progressive algorithms create images exhibiting visual artifacts at early stages. A user study investigated these artifacts' effects on user performance in appearance design tasks. Novice and expert subjects performed lighting and material editing tasks with four algorithms: random path tracing, quasirandom path tracing, progressive photon mapping, and virtual-point-light rendering. Both the novices and experts strongly preferred path tracing to progressive photon mapping and virtual-point-light rendering. None of the participants preferred random path tracing to quasirandom path tracing or vice versa; the same situation held between progressive photon mapping and virtual-point-light rendering. The user workflow didn’t differ significantly with the four algorithms. The Web Extras include a video showing how four progressive-rendering algorithms converged (at http://youtu.be/ck-Gevl1e9s), the source code used, and other supplementary materials.

The TMS Motor Map Does Not Change Following a Single Session of Mirror Training Either with Or without Motor Imagery

PubMed Central

van de Ruit, Mark; Grey, Michael J.

2017-01-01

Both motor imagery and mirror training have been used in motor rehabilitation settings to promote skill learning and plasticity. As motor imagery and mirror training are suggested to be closely linked, it was hypothesized that mirror training augmented by motor imagery would increase corticospinal excitability (CSE) significantly compared to mirror training alone. Forty-four participants were split over two experimental groups. Each participant visited the laboratory once to receive either mirror training alone or mirror training augmented with layered stimulus response training (LSRT), a type of motor imagery training. Participants performed 16 min of mirror training, making repetitive grasping movements paced by a metronome. Transcranial magnetic stimulation (TMS) mapping was performed before and after the mirror training to test for changes in CSE of the untrained hand. Self-reports suggested that the imagery training was effective in helping the participant to perform the mirror training task as instructed. Nonetheless, neither training type resulted in a significant change of TMS map area, nor was there an interaction between the groups. The results from the study revealed no effect of a single session of 16 min of either mirror training or mirror training enhanced by imagery on TMS map area. Despite the negative result of the present experiment, this does not suggest that either motor imagery or mirror training might be ineffective as a rehabilitation therapy. Further study is required to allow disentangling the role of imagery and action observation in mirror training so that mirror training can be further tailored to the individual according to their abilities. PMID:29311869

The TMS Motor Map Does Not Change Following a Single Session of Mirror Training Either with Or without Motor Imagery.

PubMed

van de Ruit, Mark; Grey, Michael J

2017-01-01

Both motor imagery and mirror training have been used in motor rehabilitation settings to promote skill learning and plasticity. As motor imagery and mirror training are suggested to be closely linked, it was hypothesized that mirror training augmented by motor imagery would increase corticospinal excitability (CSE) significantly compared to mirror training alone. Forty-four participants were split over two experimental groups. Each participant visited the laboratory once to receive either mirror training alone or mirror training augmented with layered stimulus response training (LSRT), a type of motor imagery training. Participants performed 16 min of mirror training, making repetitive grasping movements paced by a metronome. Transcranial magnetic stimulation (TMS) mapping was performed before and after the mirror training to test for changes in CSE of the untrained hand. Self-reports suggested that the imagery training was effective in helping the participant to perform the mirror training task as instructed. Nonetheless, neither training type resulted in a significant change of TMS map area, nor was there an interaction between the groups. The results from the study revealed no effect of a single session of 16 min of either mirror training or mirror training enhanced by imagery on TMS map area. Despite the negative result of the present experiment, this does not suggest that either motor imagery or mirror training might be ineffective as a rehabilitation therapy. Further study is required to allow disentangling the role of imagery and action observation in mirror training so that mirror training can be further tailored to the individual according to their abilities.

The GOL-NB program: further steps in multiple-mirror confinement research

NASA Astrophysics Data System (ADS)

Postupaev, V. V.; Batkin, V. I.; Beklemishev, A. D.; Burdakov, A. V.; Burmasov, V. S.; Chernoshtanov, I. S.; Gorbovsky, A. I.; Ivanov, I. A.; Kuklin, K. N.; Mekler, K. I.; Rovenskikh, A. F.; Sidorov, E. N.; Yurov, D. V.

2017-03-01

Physical and technical details of the GOL-NB project are presented. GOL-NB is a medium-scale multiple-mirror trap that is under development in the Budker Institute, Novosibirsk, Russia. This device will be created in several years as a deep conversion of the existing GOL-3 facility. It will consist of a central trap with two 0.75 MW neutral beams, two multiple-mirror solenoids, two expander tanks and a plasma gun that creates the start plasma. The central trap with the neutral beam injection-heated plasma is a compact gas-dynamic system. The multiple-mirror sections should decrease the power and particle losses along the magnetic field. The confinement improvement factor depends on plasma parameters and on the magnetic configuration in the multiple mirrors. The main physical task of GOL-NB is direct demonstration of the performance of multiple-mirror sections that will change equilibrium plasma parameters in the central trap. In this paper we discuss results of the scenario modeling and progress in the hardware.

Space Adaptation of Active Mirror Segment Concepts

NASA Technical Reports Server (NTRS)

Ames, Gregory H.

1999-01-01

This report summarizes the results of a three year effort by Blue Line Engineering Co. to advance the state of segmented mirror systems in several separate but related areas. The initial set of tasks were designed to address the issues of system level architecture, digital processing system, cluster level support structures, and advanced mirror fabrication concepts. Later in the project new tasks were added to provide support to the existing segmented mirror testbed at Marshall Space Flight Center (MSFC) in the form of upgrades to the 36 subaperture wavefront sensor. Still later, tasks were added to build and install a new system processor based on the results of the new system architecture. The project was successful in achieving a number of important results. These include the following most notable accomplishments: 1) The creation of a new modular digital processing system that is extremely capable and may be applied to a wide range of segmented mirror systems as well as many classes of Multiple Input Multiple Output (MIMO) control systems such as active structures or industrial automation. 2) A new graphical user interface was created for operation of segmented mirror systems. 3) The development of a high bit rate serial data loop that permits bi-directional flow of data to and from as many as 39 segments daisy-chained to form a single cluster of segments. 4) Upgrade of the 36 subaperture Hartmann type Wave Front Sensor (WFS) of the Phased Array Mirror, Extendible Large Aperture (PAMELA) testbed at MSFC resulting in a 40 to 5OX improvement in SNR which in turn enabled NASA personnel to achieve many significant strides in improved closed-loop system operation in 1998. 5) A new system level processor was built and delivered to MSFC for use with the PAMELA testbed. This new system featured a new graphical user interface to replace the obsolete and non-supported menu system originally delivered with the PAMELA system. The hardware featured Blue Line's new stackable processing system which included fiber optic data links, a WFS digital interface, and a very compact and reliable electronics package. The project also resulted in substantial advances in the evolution of concepts for integrated structures to be used to support clusters of segments while also serving as the means to distribute power, timing, and data communications resources. A prototype cluster base was built and delivered that would support a small array of 7 cm mirror segments. Another conceptual design effort led to substantial progress in the area of laminated silicon mirror segments. While finished mirrors were never successfully produced in this exploratory effort, the basic feasibility of the concept was established through a significant amount of experimental development in microelectronics processing laboratories at the University of Colorado in Colorado Springs. Ultimately lightweighted aluminum mirrors with replicated front surfaces were produced and delivered as part of a separate contract to develop integrated segmented mirror assemblies. Overall the project was very successful in advancing segmented mirror system architectures on several fronts. In fact, the results of this work have already served as the basic foundation for the system architectures of several projects proposed by Blue Line for different missions and customers. These include the NMSD and AMSD procurements for NASA's Next Generation Space Telescope, the HET figure maintenance system, and the 1 meter FAST telescope project.

Status of the secondary mirrors (M2) for the Gemini 8-m telescopes

NASA Astrophysics Data System (ADS)

Knohl, Ernst-Dieter; Schoeppach, Armin; Pickering, Michael A.

1998-08-01

The 1-m diameter lightweight secondary mirrors (M2) for the Gemini 8-m telescopes will be the largest CVD-SiC mirrors ever produced. The design and manufacture of these mirrors is a very challenging task. In this paper we will discuss the mirror design, structural and mechanical analysis, and the CVD manufacturing process used to produce the mirror blanks. The lightweight design consist of a thin faceplate (4-mm) and triangular backstructure cells with ribs of varying heights. The main drivers in the design were weight (40 kg) and manufacturing limitations imposed on the backstructure cells and mirror mounts. Finite element modeling predicts that the mirror design will meet all of the Gemini M2 requirements for weight, mechanical integrity, resonances, and optical performance. Special design considerations were necessary to avoid stress concentration in the mounting areas and to meet the requirement that the mirror survive an 8-g earthquake. The highest risk step in the mirror blank manufacturing process is the near-net-shape CVD deposition of the thin, curved faceplate. Special tooling and procedures had to be developed to produce faceplates free of fractures, cracks, and stress during the cool-down from deposition temperature (1350 C) to room temperature. Due to time delay with the CVD manufacturing process in the meantime a backup solution from Zerodur has been started. This mirror is now in the advanced polishing process. Because the design of both mirrors is very similar an excellent comparison of both solutions is possible.

Mirror movements in healthy humans across the lifespan: effects of development and ageing.

PubMed

Koerte, Inga; Eftimov, Lara; Laubender, Ruediger Paul; Esslinger, Olaf; Schroeder, Andreas Sebastian; Ertl-Wagner, Birgit; Wahllaender-Danek, Ute; Heinen, Florian; Danek, Adrian

2010-12-01

mirror movements are a transient phenomenon during childhood, which decrease in intensity with motor development. An increasing inhibitory competence resulting in the ability of movement lateralization is thought to be the underlying mechanism. We aimed to quantify unintended mirror movements systematically across the lifespan and to investigate the influences of age, sex, handedness, and task frequency. a total of 236 participants (127 females, 109 males; 216 right-handed, 20 left-handed; age range 3-96y, median 25y 8mo) first performed four clinical routine tests while mirror movements were rated by the observer. They were then asked to hold a force transducer in each hand between the thumb and index finger and to perform oscillatory grip force changes in one hand, while the other hand had to prevent the force transducer from dropping. age showed a strong nonlinear effect on the mirror-movement ratio (the amplitude ratio of the mirror and active hand, adjusted by the respective maximum grip force). Initially, there was a steep decline in the mirror-movement ratio during childhood and adolescence, followed by a gradual rise during adulthood. Males had lower mirror-movement ratios than females. The high-frequency condition triggered lower mirror-movement ratios. No significant differences of mirror movements between dominant and non-dominant hand, or left- and right-handed participants, were found. this study provides, for the first time to our knowledge, normative values of mirror movements across the lifespan that can aid differentiation between physiological and pathological mirror movements.

Broken Mirrors: Tracing Issues in Building Partner Capacity

DTIC Science & Technology

2016-06-01

environment , doctrine, and technology (EDT) provided by U.S. government agencies has complicated the issue by locking the host- nation’s success to ongoing...institutions from the ground up in conflict areas with varying social, religious, and ethnic concentrations. The interaction between the environment ...10 D. METHODOLOGY ..................................................................................10 1. Environmental Factors

Smooth leader or sharp follower? Playing the mirror game with a robot

PubMed Central

Kashi, Shir; Levy-Tzedek, Shelly

2017-01-01

Background: The increasing number of opportunities for human-robot interactions in various settings, from industry through home use to rehabilitation, creates a need to understand how to best personalize human-robot interactions to fit both the user and the task at hand. In the current experiment, we explored a human-robot collaborative task of joint movement, in the context of an interactive game. Objective: We set out to test people’s preferences when interacting with a robotic arm, playing a leader-follower imitation game (the mirror game). Methods: Twenty two young participants played the mirror game with the robotic arm, where one player (person or robot) followed the movements of the other. Each partner (person and robot) was leading part of the time, and following part of the time. When the robotic arm was leading the joint movement, it performed movements that were either sharp or smooth, which participants were later asked to rate. Results: The greatest preference was given to smooth movements. Half of the participants preferred to lead, and half preferred to follow. Importantly, we found that the movements of the robotic arm primed the subsequent movements performed by the participants. Conclusion: The priming effect by the robot on the movements of the human should be considered when designing interactions with robots. Our results demonstrate individual differences in preferences regarding the role of the human and the joint motion path of the robot and the human when performing the mirror game collaborative task, and highlight the importance of personalized human-robot interactions. PMID:29036853

Movement interference in autism-spectrum disorder.

PubMed

Gowen, E; Stanley, J; Miall, R C

2008-03-07

Movement interference occurs when concurrently observing and executing incompatible actions and is believed to be due to co-activation of conflicting populations of mirror neurons. It has also been suggested that mirror neurons contribute towards the imitation of observed actions. However, the exact neural substrate of imitation may depend on task demands: a processing route for goal-directed meaningful actions may be distinct from one for non-goal-directed actions. A more controversial role proposed for these neurons is in theory of mind processing, along with the subsequent suggestion that impairment in the mirror neuron circuit can contribute to autism-spectrum disorder (ASD) where individuals have theory of mind deficits. We have therefore examined movement interference in nine ASD participants and nine matched controls while performing actions congruent and incongruent with observed meaningless arm movements. We hypothesised that if the mirror neuron system was impaired, reduced interference should be observed in the ASD group. However, control and ASD participants demonstrated an equivalent interference effect in an interpersonal condition, with greater movement variability in the incongruent compared to the congruent condition. A component of movement interference which is independent of congruency did differ between groups: ASD participants made generally more variable movements for the interpersonal task than for biological dot-motion task, while the reverse was true for the control participants. We interpret these results as evidence that the ASD participant group either rely to a greater extent on the goal-directed imitation pathway, supporting claims that they have a specific deficit of the non-goal-directed imitation pathway, or exhibit reduced visuomotor integration.

Ray tracing: Experience at SRC

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

Severson, M.

1996-09-01

SHADOW [B. Lai and F. Cerrina, Nucl. Instrum. Methods A {bold 246}, 337 (1986)] is the primary ray-tracing program used at SRC. Ray tracing provides a tremendous amount of information regarding beamline layout, mirror sizes, resolution, alignment tolerances, and beam size at various locations. It also provides a way to check the beamline design for errors. Two recent designs have been ray traced extensively: an undulator-based, 4-meter, normal-incidence monochromator (NIM) [R. Reininger, M.C. Severson, R.W.C. Hansen, W.R. Winter, M.A. Green, and W.S. Trzeciak, Rev. Sci. Instrum. {bold 66}, 2194 (1995)] and an undulator-based, plane-grating monochromator (PGM) [R. Reininger, S.L. Crossley,more » M.A. Lagergren, M.C. Severson, and R.W.C. Hansen, Nucl. Instrum. Methods A {bold 347}, 304 (1994)]. {copyright} {ital 1996 American Institute of Physics.}« less

Investigation of Latent Traces Using Infrared Reflectance Hyperspectral Imaging

NASA Astrophysics Data System (ADS)

Schubert, Till; Wenzel, Susanne; Roscher, Ribana; Stachniss, Cyrill

2016-06-01

The detection of traces is a main task of forensics. Hyperspectral imaging is a potential method from which we expect to capture more fluorescence effects than with common forensic light sources. This paper shows that the use of hyperspectral imaging is suited for the analysis of latent traces and extends the classical concept to the conservation of the crime scene for retrospective laboratory analysis. We examine specimen of blood, semen and saliva traces in several dilution steps, prepared on cardboard substrate. As our key result we successfully make latent traces visible up to dilution factor of 1:8000. We can attribute most of the detectability to interference of electromagnetic light with the water content of the traces in the shortwave infrared region of the spectrum. In a classification task we use several dimensionality reduction methods (PCA and LDA) in combination with a Maximum Likelihood classifier, assuming normally distributed data. Further, we use Random Forest as a competitive approach. The classifiers retrieve the exact positions of labelled trace preparation up to highest dilution and determine posterior probabilities. By modelling the classification task with a Markov Random Field we are able to integrate prior information about the spatial relation of neighboured pixel labels.

Task-Based Mirror Therapy Augmenting Motor Recovery in Poststroke Hemiparesis: A Randomized Controlled Trial.

PubMed

Arya, Kamal Narayan; Pandian, Shanta; Kumar, Dharmendra; Puri, Vinod

2015-08-01

To establish the effect of the task-based mirror therapy (TBMT) on the upper limb recovery in stroke. A pilot, randomized, controlled, assessor-blinded trial was conducted in a rehabilitation institute. A convenience sample of 33 poststroke (mean duration, 12.5 months) hemiparetic subjects was randomized into 2 groups (experimental, 17; control, 16). The subjects were allocated to receive either TBMT or standard motor rehabilitation-40 sessions (5/week) for a period of 8 weeks. The TBMT group received movements using various goal-directed tasks and a mirror box. The movements were performed by the less-affected side superimposed on the affected side. The main outcome measures were Brunnstrom recovery stage (BRS) and Fugl-Meyer assessment (FMA)-FMA of upper extremity (FMA-UE), including upper arm (FMA-UA) and wrist-hand (FMA-WH). The TBMT group exhibited highly significant improvement on mean scores of FMA-WH (P < .001) and FMA-UE (P < .001) at postassessment in comparison to the control group. Furthermore, there was a 12% increase in the number of subjects at BRS stage 5 (out of synergy movement) in the experimental group as compared to a 0% rise at the same stage in the control group. This pilot trial confirmed the role of TBMT in improving the wrist-hand motor recovery in poststroke hemiparesis. MT using tasks may be used as an adjunct in stroke rehabilitation. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

The eROSITA X-ray mirrors: technology and qualification aspects of the production of mandrels, shells and mirror modules

NASA Astrophysics Data System (ADS)

Arcangeli, L.; Borghi, G.; Bräuninger, H.; Citterio, O.; Ferrario, I.; Friedrich, P.; Grisoni, G.; Marioni, F.; Predehl, P.; Rossi, M.; Ritucci, A.; Valsecchi, G.; Vernani, D.

2017-11-01

The name "eROSITA" stands for extended Roentgen Survey with an Imaging Telescope Array. The general design of the eROSITA X-ray telescope is derived from that of ABRIXAS. A bundle of 7 mirror modules with short focal lengths make up a compact telescope which is ideal for survey observations. Similar designs had been proposed for the missions DUO and ROSITA but were not realized due to programmatic shortfall. Compared to those, however, the effective area in the soft X-ray band has now much increased by adding 27 additional outer mirror shells to the original 27 ones of each mirror module. The requirement on the on-axis resolution has also been confined, namely to 15 arc seconds HEW. For these reasons the prefix "extended" was added to the original name "ROSITA". The scientific motivation for this extension is founded in the ambitious goal to detect about 100,000 clusters of galaxies which trace the large scale structure of the Universe in space and time. The X-ray telescope of eROSITA will consist of 7 identical and co-aligned mirror modules, each with 54 nested Wolter-1 mirror shells. The mirror shells are glued onto a spider wheel which is screwed to the mirror interface structure making a rigid mechanical unit. The assembly of 7 modules forms a compact hexagonal configuration with 1300 mm diameter (see Fig. 1) and will be attached to the telescope structure which connects to the 7 separate CCD cameras in the focal planes. The co-alignment of the mirror module enables eROSITA to perform also pointed observations. The replication process described in chapter III allows the manufacturing in one single piece and at the same time of both the parabola and hyperbola parts of the Wolter 1 mirror.

Effects of mirror therapy combined with motor tasks on upper extremity function and activities daily living of stroke patients.

PubMed

Kim, Kyunghoon; Lee, Sukmin; Kim, Donghoon; Lee, Kyoungbo; Kim, Youlim

2016-01-01

[Purpose] The objective of this study was to investigate the effects of mirror therapy combined with exercise tasks on the function of the upper limbs and activities of daily living. [Subjects and Methods] Twenty-five stroke patients who were receiving physical therapy at K Hospital in Gyeonggi-do, South Korea, were classified into a mirror therapy group (n=12) and a conventional therapy group (n=13). The therapies were applied for 30 minutes per day, five times per week, for a total of four weeks. Upper limb function was measured with the Action Research Arm test, the Fugl-Meyer Assessment, and the Box and Block test, and activities of daily living were measured with the Functional Independence Measure. A paired test was performed to compare the intragroup differences between before training and after four weeks of therapy, and an independent t-test was performed to compare the differences between the two groups before and after four weeks of therapy. [Results] In the intragroup comparison, both groups showed significant differences between measurements taken before and after four weeks of therapy. In the intergroup comparison, the mirror therapy group showed significant improvements compared with the conventional therapy group, both in upper limb function and activities of daily living. [Conclusion] The findings of this study demonstrated that mirror therapy is more effective than conventional therapy for the training of stroke patients to improve their upper limb function and activities of daily living.

Robotic Mirror Therapy System for Functional Recovery of Hemiplegic Arms.

PubMed

Beom, Jaewon; Koh, Sukgyu; Nam, Hyung Seok; Kim, Wonshik; Kim, Yoonjae; Seo, Han Gil; Oh, Byung-Mo; Chung, Sun Gun; Kim, Sungwan

2016-08-15

Mirror therapy has been performed as effective occupational therapy in a clinical setting for functional recovery of a hemiplegic arm after stroke. It is conducted by eliciting an illusion through use of a mirror as if the hemiplegic arm is moving in real-time while moving the healthy arm. It can facilitate brain neuroplasticity through activation of the sensorimotor cortex. However, conventional mirror therapy has a critical limitation in that the hemiplegic arm is not actually moving. Thus, we developed a real-time 2-axis mirror robot system as a simple add-on module for conventional mirror therapy using a closed feedback mechanism, which enables real-time movement of the hemiplegic arm. We used 3 Attitude and Heading Reference System sensors, 2 brushless DC motors for elbow and wrist joints, and exoskeletal frames. In a feasibility study on 6 healthy subjects, robotic mirror therapy was safe and feasible. We further selected tasks useful for activities of daily living training through feedback from rehabilitation doctors. A chronic stroke patient showed improvement in the Fugl-Meyer assessment scale and elbow flexor spasticity after a 2-week application of the mirror robot system. Robotic mirror therapy may enhance proprioceptive input to the sensory cortex, which is considered to be important in neuroplasticity and functional recovery of hemiplegic arms. The mirror robot system presented herein can be easily developed and utilized effectively to advance occupational therapy.

Maximum-performance fiber-optic irradiation with nonimaging designs.

PubMed

Fang, Y; Feuermann, D; Gordon, J M

1997-10-01

A range of practical nonimaging designs for optical fiber applications is presented. Rays emerging from a fiber over a restricted angular range (small numerical aperture) are needed to illuminate a small near-field detector at maximum radiative efficiency. These designs range from pure reflector (all-mirror), to pure dielectric (refractive and based on total internal reflection) to lens-mirror combinations. Sample designs are shown for a specific infrared fiber-optic irradiation problem of practical interest. Optical performance is checked with computer three-dimensional ray tracing. Compared with conventional imaging solutions, nonimaging units offer considerable practical advantages in compactness and ease of alignment as well as noticeably superior radiative efficiency.

A technology demonstrator for development of ultra-lightweight, large aperture, deployable telescope for space applications

NASA Astrophysics Data System (ADS)

Zuccaro Marchi, Alessandro; Gambicorti, Lisa; Simonetti, Francesca; Salinari, Piero; Lisi, Franco; Bursi, Alessandro; Olivier, Massimiliano; Gallieni, Daniele

2017-11-01

This work presents the latest results of new technological concepts for large aperture, lightweight telescopes using thin deployable active mirrors. The study is originally addressed to a spaceborne DIAL (Differential Absorption Lidar) at 935.5 nm for the measurement of water vapour profile in atmosphere, as an output of an ESA contract (whose preliminary results were presented at ICSO 2006). The high versatility of these concepts allows to exploit the presented technology for any project willing to consider large aperture, segmented lightweight telescopes. A possible scientific application is for Ultra High Energy Cosmic Rays detection through the fluorescence traces in atmosphere and diffused Cerenkov signals observation via a Schmidt-like spaceborne LEO telescope with large aperture, wide Field of View (FOV) and low f/#. A technology demonstrator has been manufactured and tested in order to investigate two project critical areas identified during the preliminary design: the performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch. In particular, this breadboard demonstrates at first that the mirror actuators are able to control with the adequate accuracy the surface shape and to recover a deployment error with their long stroke; secondly, the mirror survivability has been demonstrated using an electrostatic locking between mirror and backplane able to withstand without failure a vibration test representative of the launch environment.

Performance of Dispersed Fringe Sensor in the Presence of Segmented Mirror Aberrations: Modeling and Simulation

NASA Technical Reports Server (NTRS)

Shi, Fang; Basinger, Scott A.; Redding, David C.

2006-01-01

Dispersed Fringe Sensing (DFS) is an efficient and robust method for coarse phasing of a segmented primary mirror such as the James Webb Space Telescope (JWST). In this paper, modeling and simulations are used to study the effect of segmented mirror aberrations on the fringe image, DFS signals and DFS detection accuracy. The study has shown due to the pixilation spatial filter effect from DFS signal extraction the effect of wavefront error is reduced and DFS algorithm will be more robust against wavefront aberration by using multi-trace DFS approach. We also studied the JWST Dispersed Hartmann Sensor (DHS) performance in presence of wavefront aberrations caused by the gravity sag and we use the scaled gravity sag to explore the JWST DHS performance relationship with the level of the wavefront aberration. This also includes the effect from line-of-sight jitter.

Equations for solar tracking.

PubMed

Merlaud, Alexis; De Mazière, Martine; Hermans, Christian; Cornet, Alain

2012-01-01

Direct sunlight absorption by trace gases can be used to quantify them and investigate atmospheric chemistry. In such experiments, the main optical apparatus is often a grating or a Fourier transform spectrometer. A solar tracker based on motorized rotating mirrors is commonly used to direct the light along the spectrometer axis, correcting for the apparent rotation of the Sun. Calculating the Sun azimuth and altitude for a given time and location can be achieved with high accuracy but different sources of angular offsets appear in practice when positioning the mirrors. A feedback on the motors, using a light position sensor close to the spectrometer, is almost always needed. This paper aims to gather the main geometrical formulas necessary for the use of a widely used kind of solar tracker, based on two 45° mirrors in altazimuthal set-up with a light sensor on the spectrometer, and to illustrate them with a tracker developed by our group for atmospheric research.

Equations for Solar Tracking

PubMed Central

Merlaud, Alexis; De Mazière, Martine; Hermans, Christian; Cornet, Alain

2012-01-01

Direct sunlight absorption by trace gases can be used to quantify them and investigate atmospheric chemistry. In such experiments, the main optical apparatus is often a grating or a Fourier transform spectrometer. A solar tracker based on motorized rotating mirrors is commonly used to direct the light along the spectrometer axis, correcting for the apparent rotation of the Sun. Calculating the Sun azimuth and altitude for a given time and location can be achieved with high accuracy but different sources of angular offsets appear in practice when positioning the mirrors. A feedback on the motors, using a light position sensor close to the spectrometer, is almost always needed. This paper aims to gather the main geometrical formulas necessary for the use of a widely used kind of solar tracker, based on two 45° mirrors in altazimuthal set-up with a light sensor on the spectrometer, and to illustrate them with a tracker developed by our group for atmospheric research. PMID:22666019

Forming Mandrels for X-Ray Mirror Substrates

NASA Technical Reports Server (NTRS)

Blake, Peter N.; Saha, Timo; Zhang, Will; O'Dell, Stephen; Kester, Thomas; Jones, William

2011-01-01

Future x-ray astronomical missions, like the International X-ray Observatory (IXO), will likely require replicated mirrors to reduce both mass and production costs. Accurately figured and measured mandrels - upon which the mirror substrates are thermally formed - are essential to enable these missions. The challenge of making these mandrels within reasonable costs and schedule has led the Goddard and Marshall Space Flight Centers to develop in-house processes and to encourage small businesses to attack parts of the problem. Both Goddard and Marshall have developed full-aperture polishing processes and metrologies that yield high-precision axial traces of the finished mandrels. Outside technologists have been addressing challenges presented by subaperture CNC machining processes: particularly difficult is the challenge of reducing mid-spatial frequency errors below 2 nm rms. The end-product of this approach is a realistic plan for the economically feasible production of mandrels that meet program requirements in both figure and quantity.

Quantum nondemolition measurement of optical field fluctuations by optomechanical interaction

NASA Astrophysics Data System (ADS)

Pontin, A.; Bonaldi, M.; Borrielli, A.; Marconi, L.; Marino, F.; Pandraud, G.; Prodi, G. A.; Sarro, P. M.; Serra, E.; Marin, F.

2018-03-01

According to quantum mechanics, if we keep observing a continuous variable we generally disturb its evolution. For a class of observables, however, it is possible to implement a so-called quantum nondemolition measurement: by confining the perturbation to the conjugate variable, the observable is estimated with arbitrary accuracy, or prepared in a well-known state. For instance, when the light bounces on a movable mirror, its intensity is not perturbed (the effect is just seen on the phase of the radiation), but the radiation pressure allows one to trace back its fluctuations by observing the mirror motion. In this work, we implement a cavity optomechanical experiment based on an oscillating micromirror, and we measure correlations between the output light intensity fluctuations and the mirror motion. We demonstrate that the uncertainty of the former is reduced below the shot-noise level determined by the corpuscular nature of light.

Neural mechanisms of vocal imitation: The role of sleep replay in shaping mirror neurons.

PubMed

Giret, Nicolas; Edeline, Jean-Marc; Del Negro, Catherine

2017-06-01

Learning by imitation involves not only perceiving another individual's action to copy it, but also the formation of a memory trace in order to gradually establish a correspondence between the sensory and motor codes, which represent this action through sensorimotor experience. Memory and sensorimotor processes are closely intertwined. Mirror neurons, which fire both when the same action is performed or perceived, have received considerable attention in the context of imitation. An influential view of memory processes considers that the consolidation of newly acquired information or skills involves an active offline reprocessing of memories during sleep within the neuronal networks that were initially used for encoding. Here, we review the recent advances in the field of mirror neurons and offline processes in the songbird. We further propose a theoretical framework that could establish the neurobiological foundations of sensorimotor learning by imitation. We propose that the reactivation of neuronal assemblies during offline periods contributes to the integration of sensory feedback information and the establishment of sensorimotor mirroring activity at the neuronal level. Copyright © 2017 Elsevier Ltd. All rights reserved.

Using McStas for modelling complex optics, using simple building bricks

NASA Astrophysics Data System (ADS)

Willendrup, Peter K.; Udby, Linda; Knudsen, Erik; Farhi, Emmanuel; Lefmann, Kim

2011-04-01

The McStas neutron ray-tracing simulation package is a versatile tool for producing accurate neutron simulations, extensively used for design and optimization of instruments, virtual experiments, data analysis and user training.In McStas, component organization and simulation flow is intrinsically linear: the neutron interacts with the beamline components in a sequential order, one by one. Historically, a beamline component with several parts had to be implemented with a complete, internal description of all these parts, e.g. a guide component including all four mirror plates and required logic to allow scattering between the mirrors.For quite a while, users have requested the ability to allow “components inside components” or meta-components, allowing to combine functionality of several simple components to achieve more complex behaviour, i.e. four single mirror plates together defining a guide.We will here show that it is now possible to define meta-components in McStas, and present a set of detailed, validated examples including a guide with an embedded, wedged, polarizing mirror system of the Helmholtz-Zentrum Berlin type.

Evaluation of image quality in a Cassegrain-type telescope with an oscillating secondary mirror

NASA Technical Reports Server (NTRS)

Erickson, E. F.; Matthews, S.

1975-01-01

A ray-trace analysis is described of aberrations and extreme rays of a Cassegrain-type telescope with a tilted secondary mirror. The work was motivated by the need to understand the factors limiting image quality and to assist in the design of secondary mirrors for three telescopes with oscillating secondary mirrors (OSM) used at Ames Research Center for high altitude infrared astronomy. The telescopes are a 31-cm-diameter Dall-Kirkham (elliptical primary, spherical secondary) flown aboard a Lear jet, a 71-cm balloon-borne Dall-Kirkham flown on the AIROscope gondola, and a 91-cm true Cassegrain (parabolic primary, hyperbolic secondary) flown aboard a C-141 jet transport. The optics for these telescopes were not designed specifically for OSM operation, but all have OSM's and all must be used with various detector configurations; therefore, a facility that evaluates the performance of a telescope for a given configuration is useful. The analytical expressions are summarized and results for the above systems are discussed. Details of the calculation and a discussion of the computer program are given in the appendices.

Sleep-related memory consolidation in primary insomnia.

PubMed

Nissen, Christoph; Kloepfer, Corinna; Feige, Bernd; Piosczyk, Hannah; Spiegelhalder, Kai; Voderholzer, Ulrich; Riemann, Dieter

2011-03-01

It has been suggested that healthy sleep facilitates the consolidation of newly acquired memories and underlying brain plasticity. The authors tested the hypothesis that patients with primary insomnia (PI) would show deficits in sleep-related memory consolidation compared to good sleeper controls (GSC). The study used a four-group parallel design (n=86) to investigate the effects of 12 h of night-time, including polysomnographically monitored sleep ('sleep condition' in PI and GSC), versus 12 h of daytime wakefulness ('wake condition' in PI and GSC) on procedural (mirror tracing task) and declarative memory consolidation (visual and verbal learning task). Demographic characteristics and memory encoding did not differ between the groups at baseline. Polysomnography revealed a significantly disturbed sleep profile in PI compared to GSC in the sleep condition. Night-time periods including sleep in GSC were associated with (i) a significantly enhanced procedural and declarative verbal memory consolidation compared to equal periods of daytime wakefulness in GSC and (ii) a significantly enhanced procedural memory consolidation compared to equal periods of daytime wakefulness and night-time sleep in PI. Across retention intervals of daytime wakefulness, no differences between the experimental groups were observed. This pattern of results suggests that healthy sleep fosters the consolidation of new memories, and that this process is impaired for procedural memories in patients with PI. Future work is needed to investigate the impact of treatment on improving sleep and memory. © 2010 European Sleep Research Society.

Optimized statistical parametric mapping procedure for NIRS data contaminated by motion artifacts : Neurometric analysis of body schema extension.

PubMed

Suzuki, Satoshi

2017-09-01

This study investigated the spatial distribution of brain activity on body schema (BS) modification induced by natural body motion using two versions of a hand-tracing task. In Task 1, participants traced Japanese Hiragana characters using the right forefinger, requiring no BS expansion. In Task 2, participants performed the tracing task with a long stick, requiring BS expansion. Spatial distribution was analyzed using general linear model (GLM)-based statistical parametric mapping of near-infrared spectroscopy data contaminated with motion artifacts caused by the hand-tracing task. Three methods were utilized in series to counter the artifacts, and optimal conditions and modifications were investigated: a model-free method (Step 1), a convolution matrix method (Step 2), and a boxcar-function-based Gaussian convolution method (Step 3). The results revealed four methodological findings: (1) Deoxyhemoglobin was suitable for the GLM because both Akaike information criterion and the variance against the averaged hemodynamic response function were smaller than for other signals, (2) a high-pass filter with a cutoff frequency of .014 Hz was effective, (3) the hemodynamic response function computed from a Gaussian kernel function and its first- and second-derivative terms should be included in the GLM model, and (4) correction of non-autocorrelation and use of effective degrees of freedom were critical. Investigating z-maps computed according to these guidelines revealed that contiguous areas of BA7-BA40-BA21 in the right hemisphere became significantly activated ([Formula: see text], [Formula: see text], and [Formula: see text], respectively) during BS modification while performing the hand-tracing task.

The Ivory Tower in Violent America: An Historical Perspective.

ERIC Educational Resources Information Center

Frankhouser, Willis M.

The history of violence on university campuses mirrors that of the surrounding culture--students bring their values and standards of conduct with them to the university. This paper traces historical events which associate violence with university settings to give a sense of today's situation. The focus is on four periods representing important…

Teacher Reflection in a Hall of Mirrors: Historical Influences and Political Reverberations.

ERIC Educational Resources Information Center

Fendler, Lynn

2003-01-01

Traces the history of reflection in teacher education, focusing on its emergence through the influences of Descartes, Dewey, Schon, and feminism. Uses the critical lenses of Foucaultian genealogy and the sociology of scientific knowledge to investigate how the complicated meanings of reflection play out in complex ways through research practice.…

High-definition television evaluation for remote handling task performance

NASA Astrophysics Data System (ADS)

Fujita, Y.; Omori, E.; Hayashi, S.; Draper, J. V.; Herndon, J. N.

Described are experiments designed to evaluate the impact of HDTV (High-Definition Television) on the performance of typical remote tasks. The experiments described in this paper compared the performance of four operators using HDTV with their performance while using other television systems. The experiments included four television systems: (1) high-definition color television, (2) high-definition monochromatic television, (3) standard-resolution monochromatic television, and (4) standard-resolution stereoscopic monochromatic television. The stereo system accomplished stereoscopy by displaying two cross-polarized images, one reflected by a half-silvered mirror and one seen through the mirror. Observers wore spectacles with cross-polarized lenses so that the left eye received only the view from the left camera and the right eye received only the view from the right camera.

Doing Without Schema Hierarchies: A Recurrent Connectionist Approach to Normal and Impaired Routine Sequential Action

ERIC Educational Resources Information Center

Botvinick, Matthew; Plaut, David C.

2004-01-01

In everyday tasks, selecting actions in the proper sequence requires a continuously updated representation of temporal context. Previous models have addressed this problem by positing a hierarchy of processing units, mirroring the roughly hierarchical structure of naturalistic tasks themselves. The present study considers an alternative framework,…

Mirror neurons, the representation of word meaning, and the foot of the third left frontal convolution.

PubMed

de Zubicaray, Greig; Postle, Natasha; McMahon, Katie; Meredith, Matthew; Ashton, Roderick

2010-01-01

Previous neuroimaging research has attempted to demonstrate a preferential involvement of the human mirror neuron system (MNS) in the comprehension of effector-related action word (verb) meanings. These studies have assumed that Broca's area (or Brodmann's area 44) is the homologue of a monkey premotor area (F5) containing mouth and hand mirror neurons, and that action word meanings are shared with the mirror system due to a proposed link between speech and gestural communication. In an fMRI experiment, we investigated whether Broca's area shows mirror activity solely for effectors implicated in the MNS. Next, we examined the responses of empirically determined mirror areas during a language perception task comprising effector-specific action words, unrelated words and nonwords. We found overlapping activity for observation and execution of actions with all effectors studied, i.e., including the foot, despite there being no evidence of foot mirror neurons in the monkey or human brain. These "mirror" areas showed equivalent responses for action words, unrelated words and nonwords, with all of these stimuli showing increased responses relative to visual character strings. Our results support alternative explanations attributing mirror activity in Broca's area to covert verbalisation or hierarchical linearisation, and provide no evidence that the MNS makes a preferential contribution to comprehending action word meanings. 2008 Elsevier Inc. All rights reserved.

Principle and analysis of a rotational motion Fourier transform infrared spectrometer

NASA Astrophysics Data System (ADS)

Cai, Qisheng; Min, Huang; Han, Wei; Liu, Yixuan; Qian, Lulu; Lu, Xiangning

2017-09-01

Fourier transform infrared spectroscopy is an important technique in studying molecular energy levels, analyzing material compositions, and environmental pollutants detection. A novel rotational motion Fourier transform infrared spectrometer with high stability and ultra-rapid scanning characteristics is proposed in this paper. The basic principle, the optical path difference (OPD) calculations, and some tolerance analysis are elaborated. The OPD of this spectrometer is obtained by the continuously rotational motion of a pair of parallel mirrors instead of the translational motion in traditional Michelson interferometer. Because of the rotational motion, it avoids the tilt problems occurred in the translational motion Michelson interferometer. There is a cosine function relationship between the OPD and the rotating angle of the parallel mirrors. An optical model is setup in non-sequential mode of the ZEMAX software, and the interferogram of a monochromatic light is simulated using ray tracing method. The simulated interferogram is consistent with the theoretically calculated interferogram. As the rotating mirrors are the only moving elements in this spectrometer, the parallelism of the rotating mirrors and the vibration during the scan are analyzed. The vibration of the parallel mirrors is the main error during the rotation. This high stability and ultra-rapid scanning Fourier transform infrared spectrometer is a suitable candidate for airborne and space-borne remote sensing spectrometer.

Optical Analysis of Grazing Incidence Ring Resonators for Free-Electron Lasers

NASA Astrophysics Data System (ADS)

Gabardi, David Richard

1990-08-01

The design of resonators for free-electron lasers (FELs) which are to operate in the soft x-ray/vacuum ultraviolet (XUV) region of the spectrum is complicated by the fact that, in this wavelength regime, normal incidence mirrors, which would otherwise be used for the construction of the resonators, generally have insufficient reflectivities for this purpose. However, the use of grazing incidence mirrors in XUV resonators offers the possibility of (1) providing sufficient reflectivity, (2) a lessening of the mirrors' thermal loads due to the projection of the laser beam onto an oblique surface, and (3) the preservation of the FEL's tunability. In this work, the behavior of resonators employing grazing incidence mirrors in ring type configurations is explored. In particular, two designs, each utilizing four off-axis conic mirrors and a number of flats, are examined. In order to specify the location, orientation, and surface parameters for the mirrors in these resonators, a design algorithm has been developed based upon the properties of Gaussian beam propagation. Two computer simulation methods are used to perform a vacuum stability analysis of the two resonator designs. The first method uses paraxial ray trace techniques with the resonators' thin lens analogues while the second uses the diffraction-based computer simulation code GLAD (General Laser Analysis and Design). The effects of mirror tilts and deviations in the mirror surface parameters are investigated for a number of resonators designed to propagate laser beams of various Rayleigh ranges. It will be shown that resonator stability decreases as the laser wavelength for which the resonator was designed is made smaller. In addition, resonator stability will also be seen to decrease as the amount of magnification the laser beam receives as it travels around the resonator is increased.

[When shape-invariant recognition ('A' = 'a') fails. A case study of pure alexia and kinesthetic facilitation].

PubMed

Diesfeldt, H F A

2011-06-01

A right-handed patient, aged 72, manifested alexia without agraphia, a right homonymous hemianopia and an impaired ability to identify visually presented objects. He was completely unable to read words aloud and severely deficient in naming visually presented letters. He responded to orthographic familiarity in the lexical decision tasks of the Psycholinguistic Assessments of Language Processing in Aphasia (PALPA) rather than to the lexicality of the letter strings. He was impaired at deciding whether two letters of different case (e.g., A, a) are the same, though he could detect real letters from made-up ones or from their mirror image. Consequently, his core deficit in reading was posited at the level of the abstract letter identifiers. When asked to trace a letter with his right index finger, kinesthetic facilitation enabled him to read letters and words aloud. Though he could use intact motor representations of letters in order to facilitate recognition and reading, the slow, sequential and error-prone process of reading letter by letter made him abandon further training.

The acquisition of socio-motor improvisation in the mirror game.

PubMed

Gueugnon, Mathieu; Salesse, Robin N; Coste, Alexandre; Zhao, Zhong; Bardy, Benoît G; Marin, Ludovic

2016-04-01

Socio-motor improvisation is defined as the creative action of two or more people without a script or anticipated preparation. It is evaluated through two main parameters: movement synchronization and movement richness. Experts in art (e.g., dance, theater or music) are known to exhibit higher synchronization and to perform richer movements during interpersonal improvisation, but how these competences evolve over time is largely unknown. In the present study, we investigated whether performing more synchronized and richer movements over time can promote the acquisition of improvisation. Pairs of novice participants were instructed to play an improvisation mirror game in three different sessions. Between sessions, they performed an unintended interpersonal coordination task in which synchronization and richness were manipulated, resulting in four different groups of dyads. Our results demonstrate that synchronization during improvisation improved for all groups whereas movement richness only enhanced for dyads that performed synchronized movements during unintended coordination tasks. Our findings suggest that movement synchrony contributes more than movement richness to the acquisition of socio-motor improvisation in the mirror game. Copyright © 2015 Elsevier B.V. All rights reserved.

Mirror-image discrimination in the literate brain: a causal role for the left occpitotemporal cortex.

PubMed

Nakamura, Kimihiro; Makuuchi, Michiru; Nakajima, Yasoichi

2014-01-01

Previous studies show that the primate and human visual system automatically generates a common and invariant representation from a visual object image and its mirror reflection. For humans, however, this mirror-image generalization seems to be partially suppressed through literacy acquisition, since literate adults have greater difficulty in recognizing mirror images of letters than those of other visual objects. At the neural level, such category-specific effect on mirror-image processing has been associated with the left occpitotemporal cortex (L-OTC), but it remains unclear whether the apparent "inhibition" on mirror letters is mediated by suppressing mirror-image representations covertly generated from normal letter stimuli. Using transcranial magnetic stimulation (TMS), we examined how transient disruption of the L-OTC affects mirror-image recognition during a same-different judgment task, while varying the semantic category (letters and non-letter objects), identity (same or different), and orientation (same or mirror-reversed) of the first and second stimuli. We found that magnetic stimulation of the L-OTC produced a significant delay in mirror-image recognition for letter-strings but not for other objects. By contrast, this category specific impact was not observed when TMS was applied to other control sites, including the right homologous area and vertex. These results thus demonstrate a causal link between the L-OTC and mirror-image discrimination in literate people. We further suggest that left-right sensitivity for letters is not achieved by a local inhibitory mechanism in the L-OTC but probably relies on the inter-regional coupling with other orientation-sensitive occipito-parietal regions.

Acquisition of Motor and Cognitive Skills through Repetition in Typically Developing Children

PubMed Central

Magallón, Sara; Narbona, Juan; Crespo-Eguílaz, Nerea

2016-01-01

Background Procedural memory allows acquisition, consolidation and use of motor skills and cognitive routines. Automation of procedures is achieved through repeated practice. In children, improvement in procedural skills is a consequence of natural neurobiological development and experience. Methods The aim of the present research was to make a preliminary evaluation and description of repetition-based improvement of procedures in typically developing children (TDC). Ninety TDC children aged 6–12 years were asked to perform two procedural learning tasks. In an assembly learning task, which requires predominantly motor skills, we measured the number of assembled pieces in 60 seconds. In a mirror drawing learning task, which requires more cognitive functions, we measured time spent and efficiency. Participants were tested four times for each task: three trials were consecutive and the fourth trial was performed after a 10-minute nonverbal interference task. The influence of repeated practice on performance was evaluated by means of the analysis of variance with repeated measures and the paired-sample test. Correlation coefficients and simple linear regression test were used to examine the relationship between age and performance. Results TDC achieved higher scores in both tasks through repetition. Older children fitted more pieces than younger ones in assembling learning and they were faster and more efficient at the mirror drawing learning task. Conclusions These findings indicate that three consecutive trials at a procedural task increased speed and efficiency, and that age affected basal performance in motor-cognitive procedures. PMID:27384671

Acquisition of Motor and Cognitive Skills through Repetition in Typically Developing Children.

PubMed

Magallón, Sara; Narbona, Juan; Crespo-Eguílaz, Nerea

2016-01-01

Procedural memory allows acquisition, consolidation and use of motor skills and cognitive routines. Automation of procedures is achieved through repeated practice. In children, improvement in procedural skills is a consequence of natural neurobiological development and experience. The aim of the present research was to make a preliminary evaluation and description of repetition-based improvement of procedures in typically developing children (TDC). Ninety TDC children aged 6-12 years were asked to perform two procedural learning tasks. In an assembly learning task, which requires predominantly motor skills, we measured the number of assembled pieces in 60 seconds. In a mirror drawing learning task, which requires more cognitive functions, we measured time spent and efficiency. Participants were tested four times for each task: three trials were consecutive and the fourth trial was performed after a 10-minute nonverbal interference task. The influence of repeated practice on performance was evaluated by means of the analysis of variance with repeated measures and the paired-sample test. Correlation coefficients and simple linear regression test were used to examine the relationship between age and performance. TDC achieved higher scores in both tasks through repetition. Older children fitted more pieces than younger ones in assembling learning and they were faster and more efficient at the mirror drawing learning task. These findings indicate that three consecutive trials at a procedural task increased speed and efficiency, and that age affected basal performance in motor-cognitive procedures.

Parallel plan execution with self-processing networks

NASA Technical Reports Server (NTRS)

Dautrechy, C. Lynne; Reggia, James A.

1989-01-01

A critical issue for space operations is how to develop and apply advanced automation techniques to reduce the cost and complexity of working in space. In this context, it is important to examine how recent advances in self-processing networks can be applied for planning and scheduling tasks. For this reason, the feasibility of applying self-processing network models to a variety of planning and control problems relevant to spacecraft activities is being explored. Goals are to demonstrate that self-processing methods are applicable to these problems, and that MIRRORS/II, a general purpose software environment for implementing self-processing models, is sufficiently robust to support development of a wide range of application prototypes. Using MIRRORS/II and marker passing modelling techniques, a model of the execution of a Spaceworld plan was implemented. This is a simplified model of the Voyager spacecraft which photographed Jupiter, Saturn, and their satellites. It is shown that plan execution, a task usually solved using traditional artificial intelligence (AI) techniques, can be accomplished using a self-processing network. The fact that self-processing networks were applied to other space-related tasks, in addition to the one discussed here, demonstrates the general applicability of this approach to planning and control problems relevant to spacecraft activities. It is also demonstrated that MIRRORS/II is a powerful environment for the development and evaluation of self-processing systems.

Simulation of Mirror Electron Microscopy Caustic Images in Three-Dimensions

NASA Astrophysics Data System (ADS)

Kennedy, S. M.; Zheng, C. X.; Jesson, D. E.

A full, three-dimensional (3D) ray tracing approach is developed to simulate the caustics visible in mirror electron microscopy (MEM). The method reproduces MEM image contrast resulting from 3D surface relief. To illustrate the potential of the simulation methods, we study the evolution of crater contrast associated with a movie of GaAs structures generated by the droplet epitaxy technique. Specifically, we simulate the image contrast resulting from both a precursor stage and the final crater morphology which is consistent with an inverted pyramid consisting of (111) facet walls. The method therefore facilities the study of how self-assembled quantum structures evolve with time and, in particular, the development of anisotropic features including faceting.

Results of x-ray mirror round-robin metrology measurements at the APS, ESRF, and SPring-8 optical metrology laboratories.

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

Assoufid, L.; Rommeveaux, A.; Ohashi, H.

2005-01-01

This paper presents the first series of round-robin metrology measurements of x-ray mirrors organized at the Advanced Photon Source (APS) in the USA, the European Synchrotron Radiation Facility in France, and the Super Photon Ring (SPring-8) (in a collaboration with Osaka University, ) in Japan. This work is part of the three institutions' three-way agreement to promote a direct exchange of research information and experience amongst their specialists. The purpose of the metrology round robin is to compare the performance and limitations of the instrumentation used at the optical metrology laboratories of these facilities and to set the basis formore » establishing guidelines and procedures to accurately perform the measurements. The optics used in the measurements were selected to reflect typical, as well as state of the art, in mirror fabrication. The first series of the round robin measurements focuses on flat and cylindrical mirrors with varying sizes and quality. Three mirrors (two flats and one cylinder) were successively measured using long trace profilers. Although the three facilities' LTPs are of different design, the measurements were found to be in excellent agreement. The maximum discrepancy of the rms slope error values is 0.1 {micro}rad, that of the rms shape error was 3 nm, and they all relate to the measurement of the cylindrical mirror. The next round-robin measurements will deal with elliptical and spherical optics.« less

Mothers' Predictions of Their Son's Executive Functioning Skills: Relations to Child Behavior Problems

ERIC Educational Resources Information Center

Johnston, Charlotte

2011-01-01

This study examined mothers' ability to accurately predict their sons' performance on executive functioning tasks in relation to the child's behavior problems. One-hundred thirteen mothers and their 4-7 year old sons participated. From behind a one-way mirror, mothers watched their sons perform tasks assessing inhibition and planning skills.…

Sex Differences in Mental Rotation Tasks: Not Just in the Mental Rotation Process!

ERIC Educational Resources Information Center

Boone, Alexander P.; Hegarty, Mary

2017-01-01

The paper-and-pencil Mental Rotation Test (Vandenberg & Kuse, 1978) consistently produces large sex differences favoring men (Voyer, Voyer, & Bryden, 1995). In this task, participants select 2 of 4 answer choices that are rotations of a probe stimulus. Incorrect choices (i.e., foils) are either mirror reflections of the probe or…

Rightward Biases in Free-Viewing Visual Bisection Tasks: Implications for Leftward Responses Biases on Similar Tasks

ERIC Educational Resources Information Center

Elias, Lorin J.; Robinson, Brent; Saucier, Deborah M.

2005-01-01

Neurologically normal individuals exhibit strong leftward response biases during free-viewing perceptual judgments of brightness, quantity, and size. When participants view two mirror-reversed objects and they are forced to choose which object appears darker, more numerous, or larger, the stimulus with the relevant feature on the left side is…

Attribution of Conditions for School Performance

ERIC Educational Resources Information Center

Flammer, August; Schmid, David

2003-01-01

210 children (110 girls and 100 boys) were interviewed individually about causes that lead to success or to failure in school tests. They were presented fictitious scenarios about an unknown peer who had either success or failure in a dictation task and a sums task. The free answers were taken as mirroring means-ends beliefs of the interviewed…

Mirrors, masks, and motivation: implicit and explicit self-focused attention influence effort-related cardiovascular reactivity.

PubMed

Silvia, Paul J

2012-07-01

Using motivational intensity theory as a framework, three experiments examined how implicit self-focus (manipulated with masked first-name priming) and explicit self-focus (manipulated with a large mirror) influence effort-related cardiovascular activity, particularly systolic blood pressure reactivity. Theories of self-focused attention suggest that both implicit and explicit self-focus bring about self-evaluation and thus make meeting a goal more important. For a "do your best" task of unfixed difficulty, implicit and explicit self-focus both increased effort (Experiment 1) compared to a control condition. For a task that varied in difficulty, implicit and explicit self-focus promoted more effort as the task became increasingly hard (Experiments 2 and 3). Taken together, the findings suggest that implicit and explicit self-processes share a similar motivational architecture. The discussion explores the value of integrating motivational intensity theory with self-awareness theory and considers the emerging interest in implicit aspects of effort regulation. Copyright © 2012 Elsevier B.V. All rights reserved.

Distributed Task Offloading in Heterogeneous Vehicular Crowd Sensing

PubMed Central

Liu, Yazhi; Wang, Wendong; Ma, Yuekun; Yang, Zhigang; Yu, Fuxing

2016-01-01

The ability of road vehicles to efficiently execute different sensing tasks varies because of the heterogeneity in their sensing ability and trajectories. Therefore, the data collection sensing task, which requires tempo-spatial sensing data, becomes a serious problem in vehicular sensing systems, particularly those with limited sensing capabilities. A utility-based sensing task decomposition and offloading algorithm is proposed in this paper. The utility function for a task executed by a certain vehicle is built according to the mobility traces and sensing interfaces of the vehicle, as well as the sensing data type and tempo-spatial coverage requirements of the sensing task. Then, the sensing tasks are decomposed and offloaded to neighboring vehicles according to the utilities of the neighboring vehicles to the decomposed sensing tasks. Real trace-driven simulation shows that the proposed task offloading is able to collect much more comprehensive and uniformly distributed sensing data than other algorithms. PMID:27428967

Does Time-on-Task Estimation Matter? Implications for the Validity of Learning Analytics Findings

ERIC Educational Resources Information Center

Kovanovic, Vitomir; Gaševic, Dragan; Dawson, Shane; Joksimovic, Srecko; Baker, Ryan S.; Hatala, Marek

2015-01-01

With\twidespread adoption of Learning Management Systems (LMS) and other learning technology, large amounts of data--commonly known as trace data--are readily accessible to researchers. Trace data has been extensively used to calculate time that students spend on different learning activities--typically referred to as time-on-task. These measures…

Production of the 4.26 m ZERODUR mirror blank for the Advanced Technology Solar telescope (ATST)

NASA Astrophysics Data System (ADS)

Jedamzik, Ralf; Werner, Thomas; Westerhoff, Thomas

2014-07-01

The Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope, ATST) will be the most powerful solar telescope in the world. It is currently being built by the Association of Universities for Research in Astronomy (AURA) in a height of 3000 m above sea level on the mountain Haleakala of Maui, Hawaii. The primary mirror blank of diameter 4.26 m is made of the extremely low thermal expansion glass ceramic ZERODUR® of SCHOTT AG Advanced Optics. The DKIST primary mirror design is extremely challenging. With a mirror thickness of only 78 to 85 mm it is the smallest thickness ever machined on a mirror of 4.26 m in diameter. Additionally the glassy ZERODUR® casting is one of the largest in size ever produced for a 4 m class ZERODUR® mirror blank. The off axis aspherical mirror surface required sophisticated grinding procedures to achieve the specified geometrical tolerance. The small thickness of about 80 mm required special measures during processing, lifting and transport. Additionally acid etch treatment was applied to the convex back-surface and the conical shaped outer diameter surface to improve the strength of the blank. This paper reports on the challenging tasks and the achievements on the material property and dimensional specification parameter during the production of the 4.26 m ZERODUR® primary mirror blank for AURA.

Biases in rhythmic sensorimotor coordination: effects of modality and intentionality.

PubMed

Debats, Nienke B; Ridderikhoff, Arne; de Boer, Betteco J; Peper, C Lieke E

2013-08-01

Sensorimotor biases were examined for intentional (tracking task) and unintentional (distractor task) rhythmic coordination. The tracking task involved unimanual tracking of either an oscillating visual signal or the passive movements of the contralateral hand (proprioceptive signal). In both conditions the required coordination patterns (isodirectional and mirror-symmetric) were defined relative to the body midline and the hands were not visible. For proprioceptive tracking the two patterns did not differ in stability, whereas for visual tracking the isodirectional pattern was performed more stably than the mirror-symmetric pattern. However, when visual feedback about the unimanual hand movements was provided during visual tracking, the isodirectional pattern ceased to be dominant. Together these results indicated that the stability of the coordination patterns did not depend on the modality of the target signal per se, but on the combination of sensory signals that needed to be processed (unimodal vs. cross-modal). The distractor task entailed rhythmic unimanual movements during which a rhythmic visual or proprioceptive distractor signal had to be ignored. The observed biases were similar as for intentional coordination, suggesting that intentionality did not affect the underlying sensorimotor processes qualitatively. Intentional tracking was characterized by active sensory pursuit, through muscle activity in the passively moved arm (proprioceptive tracking task) and rhythmic eye movements (visual tracking task). Presumably this pursuit afforded predictive information serving the coordination process. Copyright © 2013 Elsevier B.V. All rights reserved.

Technician checks the mirrors of the Starshine-2 experiment

NASA Technical Reports Server (NTRS)

2001-01-01

Technician checks the mirrors of the Starshine-2 experiment KSC-01PD-1715 KENNEDY SPACE CENTER, Fla. -- A technician checks the mirrors on the Starshine-2 experiment inside a canister in the payload bay of Space Shuttle Endeavour. The deployable experiment is being carried on mission STS-108. Starshine-2's 800 aluminum mirrors were polished by more than 25,000 students from 26 countries. Top priorities for the STS-108 (UF-1) mission of Endeavour are rotation of the International Space Station Expedition Three and Expedition Four crews, bringing water, equipment and supplies to the station in the Multi-Purpose Logistics Module Raffaello, and completion of robotics tasks and a spacewalk to install thermal blankets over two pieces of equipment at the bases of the Space Station's solar wings. Liftoff of Endeavour on mission STS-108 is scheduled for 7:41 p.m. EST.

A happy conclusion to the SALT image quality saga

NASA Astrophysics Data System (ADS)

Crause, Lisa A.; O'Donoghue, Darragh E.; O'Connor, James E.; Strumpfer, Francois; Strydom, Ockert J.; Sass, Craig; du Plessis, Charl A.; Wiid, Eben; Love, Jonathan; Brink, Janus D.; Wilkinson, Martin; Coetzee, Chris

2012-09-01

Images obtained with the Southern African Large Telescope (SALT) during its commissioning phase showed degradation due to a large focus gradient and a variety of other optical aberrations. An extensive forensic investigation eventually traced the problem to the mechanical interface between the telescope and the secondary optics that form the Spherical Aberration Corrector (SAC). The SAC was brought down from the telescope in 2009 April, the problematic interface was replaced and the four corrector mirrors were optically tested and re-aligned. The surface figures of the SAC mirrors were confirmed to be within specification and a full system test following the re-alignment process yielded a RMS wavefront error of just 0.15 waves. The SAC was re-installed on the tracker in 2010 August and aligned with respect to the payload and primary mirror. Subsequent on-sky tests produced alarming results which were due to spurious signals being sent to the tracker by the auto-collimator, the instrument responsible for controlling the attitude of the SAC with respect to the primary mirror. Once this minor issue was resolved, we obtained uniform 1.1 arcsecond star images over the full 10 arcminute field of view of the telescope.

Mutual optical intensity propagation through non-ideal mirrors

DOE PAGES

Meng, Xiangyu; Shi, Xianbo; Wang, Yong; ...

2017-08-18

The mutual optical intensity (MOI) model is extended to include the propagation of partially coherent radiation through non-ideal mirrors. The propagation of the MOI from the incident to the exit plane of the mirror is realised by local ray tracing. The effects of figure errors can be expressed as phase shifts obtained by either the phase projection approach or the direct path length method. Using the MOI model, the effects of figure errors are studied for diffraction-limited cases using elliptical cylinder mirrors. Figure errors with low spatial frequencies can vary the intensity distribution, redistribute the local coherence function and distortmore » the wavefront, but have no effect on the global degree of coherence. The MOI model is benchmarked againstHYBRIDand the multi-electronSynchrotron Radiation Workshop(SRW) code. The results show that the MOI model gives accurate results under different coherence conditions of the beam. Other than intensity profiles, the MOI model can also provide the wavefront and the local coherence function at any location along the beamline. The capability of tuning the trade-off between accuracy and efficiency makes the MOI model an ideal tool for beamline design and optimization.« less

Investigation of Primary Mirror Segment's Residual Errors for the Thirty Meter Telescope

NASA Technical Reports Server (NTRS)

Seo, Byoung-Joon; Nissly, Carl; Angeli, George; MacMynowski, Doug; Sigrist, Norbert; Troy, Mitchell; Williams, Eric

2009-01-01

The primary mirror segment aberrations after shape corrections with warping harness have been identified as the single largest error term in the Thirty Meter Telescope (TMT) image quality error budget. In order to better understand the likely errors and how they will impact the telescope performance we have performed detailed simulations. We first generated unwarped primary mirror segment surface shapes that met TMT specifications. Then we used the predicted warping harness influence functions and a Shack-Hartmann wavefront sensor model to determine estimates for the 492 corrected segment surfaces that make up the TMT primary mirror. Surface and control parameters, as well as the number of subapertures were varied to explore the parameter space. The corrected segment shapes were then passed to an optical TMT model built using the Jet Propulsion Laboratory (JPL) developed Modeling and Analysis for Controlled Optical Systems (MACOS) ray-trace simulator. The generated exit pupil wavefront error maps provided RMS wavefront error and image-plane characteristics like the Normalized Point Source Sensitivity (PSSN). The results have been used to optimize the segment shape correction and wavefront sensor designs as well as provide input to the TMT systems engineering error budgets.

Methods for reducing singly reflected rays on the Wolter-I focusing mirrors of the FOXSI rocket experiment

NASA Astrophysics Data System (ADS)

Buitrago-Casas, Juan Camilo; Elsner, Ronald; Glesener, Lindsay; Christe, Steven; Ramsey, Brian; Courtade, Sasha; Ishikawa, Shin-nosuke; Narukage, Noriyuki; Turin, Paul; Vievering, Juliana; Athiray, P. S.; Musset, Sophie; Krucker, Säm.

2017-08-01

In high energy solar astrophysics, imaging hard X-rays by direct focusing offers higher dynamic range and greater sensitivity compared to past techniques that used indirect imaging. The Focusing Optics X-ray Solar Imager (FOXSI) is a sounding rocket payload that uses seven sets of nested Wolter-I figured mirrors together with seven high-sensitivity semiconductor detectors to observe the Sun in hard X-rays through direct focusing. The FOXSI rocket has successfully flown twice and is funded to fly a third time in summer 2018. The Wolter-I geometry consists of two consecutive mirrors, one paraboloid and one hyperboloid, that reflect photons at grazing angles. Correctly focused X-rays reflect once per mirror segment. For extended sources, like the Sun, off-axis photons at certain incident angles can reflect on only one mirror and still reach the focal plane, generating a background pattern of singly reflected rays (i.e., ghost rays) that can limit the sensitivity of the observation to faint, focused sources. Understanding and mitigating the impact of the singly reflected rays on the FOXSI optical modules will maximize the instruments' sensitivity to background-limited sources. We present an analysis of the FOXSI singly reflected rays based on ray-tracing simulations and laboratory measurements, as well as the effectiveness of different physical strategies to reduce them.

An experimental apparatus for diffraction-limited soft x-ray nano-focusing

NASA Astrophysics Data System (ADS)

Merthe, Daniel J.; Goldberg, Kenneth A.; Yashchuk, Valeriy V.; Yuan, Sheng; McKinney, Wayne R.; Celestre, Richard; Mochi, Iacopo; Macdougall, James; Morrison, Gregory Y.; Rakawa, Senajith B.; Anderson, Erik; Smith, Brian V.; Domning, Edward E.; Warwick, Tony; Padmore, Howard

2011-09-01

Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing. The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. Visible-light long-trace profilometry was used to pre-align the mirror before installation at the beamline. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

Development and calibration of mirrors and gratings for the Soft X-ray materials science beamline at the Linac Coherent Light Source free-electron laser

DOE PAGES

Soufli, Regina; Fernandez-Perea, Monica; Baker, Sherry L.; ...

2012-04-18

This article discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 – 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B 4C) coating especially optimized for the LCLS FEL conditions was deposited onmore » all SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B 4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.« less

NREL's Education Program in Action in the Concentrating Solar Power Program Advanced Materials Task

NASA Astrophysics Data System (ADS)

Kennedy, Cheryl

2010-03-01

Concentrating solar power (CSP) technologies use large mirrors to concentrate sunlight and the thermal energy collected is converted to electricity. The CSP industry is growing rapidly and is expected to reach 25 GW globally by 2020. Cost target goals are for CSP technologies to produce electricity competitive with intermediate-load power generation (i.e., natural gas) by 2015 with 6 hours of thermal storage and competitive in carbon constrained base load power markets (i.e., coal) by 2020 with 12-17 hours of thermal storage. The solar field contributes more than 40% of the total cost of a parabolic trough plant and together the mirrors and receivers contribute more than 25% of the installed solar field cost. CSP systems cannot hit these targets without aggressive cost reductions and revolutionary performance improvements from technology advances. NREL's Advanced Materials task in the CSP Advanced R&D project performs research to develop low cost, high performance, durable solar reflector and high-temperature receiver materials to meet these needs. The Advanced Materials task leads the world in this research and the task's reliance on NREL's educational program will be discussed.

Atmospheric lidar multi-user instrument system definition study

NASA Technical Reports Server (NTRS)

Greco, R. V. (Editor)

1980-01-01

A spaceborne lidar system for atmospheric studies was defined. The primary input was the Science Objectives Experiment Description and Evolutionary Flow Document. The first task of the study was to perform an experiment evolutionary analysis of the SEED. The second task was the system definition effort of the instrument system. The third task was the generation of a program plan for the hardware phase. The fourth task was the supporting studies which included a Shuttle deficiency analysis, a preliminary safety hazard analysis, the identification of long lead items, and development studies required. As a result of the study an evolutionary Lidar Multi-User Instrument System (MUIS) was defined. The MUIS occupies a full Spacelab pallet and has a weight of 1300 kg. The Lidar MUIS laser provides a 2 joule frequency doubled Nd:YAG laser that can also pump a tuneable dye laser wide frequency range and bandwidth. The MUIS includes a 1.25 meter diameter aperture Cassegrain receiver, with a moveable secondary mirror to provide precise alignment with the laser. The receiver can transmit the return signal to three single and multiple photomultiple tube detectors by use of a rotating fold mirror. It is concluded that the Lidar MUIS proceed to program implementation.

Basic and applied research program. Semiannual report, July-December 1978

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

Butler, B.L.

1979-12-01

The status of research projects in the Basic and Applied Research Program at SERI is presented for the semiannual period ending December 31, 1978. The five tasks in this program are grouped into Materials Research and Development, Materials Processing and Development, Photoconversion Research, Exploratory Research, and Energy Resource and Assessment and have been carried out by personnel in the Materials, Bio/Chemical Conversion, and Energy Resource and Assessment Branches. Subtask elements in the task areas include coatings and films, polymers, metallurgy and corrosion, optical materials, surfaces and interfaces in materials research and development; photochemistry, photoelectrochemistry, and photobiology in photoconversion; thin glassmore » mirror development, silver degradation of mirrors, hail resistance of thin glass, thin glass manufacturing, cellular glass development, and sorption by desiccants in materials processing and development; and thermoelectric energy conversion, desiccant cooling, photothermal degradation, and amorphous materials in exploratory research. For each task or subtask element, the overview, scope, goals, approach, apparatus and equipment, and supporting subcontracts are presented, as applicable, in addition to the status of the projects in each task or subtask. Listing of publications and reports authored by personnel associated with the Basic and Applied Research Program and prepared or published during 1978 are also included.« less

Mirror gait retraining for the treatment of patellofemoral pain in female runners

PubMed Central

Willy, Richard W.; Scholz, John P.; Davis, Irene S.

2012-01-01

Background Abnormal hip mechanics are often implicated in female runners with patellofemoral pain. We sought to evaluate a simple gait retraining technique, using a full-length mirror, in female runners with patellofemoral pain and abnormal hip mechanics. Transfer of the new motor skill to the untrained tasks of single leg squat and step descent was also evaluated. Methods Ten female runners with patellofemoral pain completed 8 sessions of mirror and verbal feedback on their lower extremity alignment during treadmill running. During the last 4 sessions, mirror and verbal feedback were progressively removed. Hip mechanics were assessed during running gait, a single leg squat and a step descent, both pre- and post-retraining. Subjects returned to their normal running routines and analyses were repeated at 1-month and 3-month post-retraining. Data were analyzed via repeated measures analysis of variance. Findings Subjects reduced peaks of hip adduction, contralateral pelvic drop, and hip abduction moment during running (P<0.05, effect size=0.69–2.91). Skill transfer to single leg squatting and step descent was noted (P<0.05, effect size=0.91–1.35). At 1 and 3 months post retraining, most mechanics were maintained in the absence of continued feedback. Subjects reported improvements in pain and function (P<0.05, effect size=3.81–7.61) and maintained through 3 months post retraining. Interpretation Mirror gait retraining was effective in improving mechanics and measures of pain and function. Skill transfer to the untrained tasks of squatting and step descent indicated that a higher level of motor learning had occurred. Extended follow-up is needed to determine the long term efficacy of this treatment. PMID:22917625

Design and fabrication of embedded micro-mirror inserts for out-of-plane coupling in PCB-level optical interconnections

NASA Astrophysics Data System (ADS)

Van Erps, Jurgen; Hendrickx, Nina; Bosman, Erwin; Van Daele, Peter; Debaes, Christof; Thienpont, Hugo

2010-05-01

Optical interconnections have gained interest over the last years, and several approaches have been presented for the integration of optics to the printed circuit board (PCB)-level. The use of a polymer optical waveguide layer appears to be the prevailing solution to route optical signals on the PCB. The most difficult issue is the efficient out-of-plane coupling of light between surface-normal optoelectronic devices (lasers and photodetectors) and PCB-integrated waveguides. The most common approach consists of using 45° reflecting micro-mirrors. The micro-mirror performance significantly affects the total insertion loss of the optical interconnect system, and hence has a crucial role on the system's bit error rate (BER) characteristics. Several technologies have been proposed for the fabrication of 45° reflector micro-mirrors directly into waveguides. Alternatively, it is possible to make use of discrete coupling components which have to be inserted into cavities formed in the PCB-integrated waveguides. In this paper, we present a hybrid approach where we try to combine the advantages of integrated and discrete coupling mirrors, i.e. low coupling loss and maintenance of the planararity of the top surface of the optical layer, allowing the lamination of additional layers or the mounting of optoelectronic devices. The micro-mirror inserts are designed through non-sequential ray tracing simulations, including a tolerance analysis, and subsequently prototyped with Deep Proton Writing (DPW). The DPW prototypes are compatible with mass fabrication at low cost in a wide variety of high-tech plastics. The DPW micro-mirror insert is metallized and inserted in a laser ablated cavity in the optical layer and in a next step covered with cladding material. Surface roughness measurements confirm the excellent quality of the mirror facet. An average mirror loss of 0.35-dB was measured in a receiver scheme, which is the most stringent configuration. Finally, the configuration is robust, since the mirror is embedded and thus protected from environmental contamination, like dust or moisture adsorption, which makes them interesting candidates for out-of-plane coupling in high-end boards.

Effects of observation of hand movements reflected in a mirror on cortical activation in patients with stroke

PubMed Central

Chang, Moon-Young; Kim, Hwan-Hee; Kim, Kyeong-Mi; Oh, Jae-Seop; Jang, Chel; Yoon, Tae-Hyung

2017-01-01

[Purpose] The purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention. [Subjects and Methods] The subjects of this study were 14 patients with stroke (6 females and 8 males). The subjects were assessed by measuring the alpha and beta waves of the EEG (QEEG-32 system CANS 3000). The mirror therapy intervention was delivered over the course of four weeks (a total of 20 sessions). [Results] Relative alpha power showed statistically significant differences in the F3, F4, O1, and O2 channels in the situation comparison and higher for hand observation than for mirror observation. Relative beta power showed statistically significant differences in the F3, F4, C3, and C4 channels. [Conclusion] This study analyzed activity of the brain in each area when patients with stroke observed movements reflected in a mirror, and future research on diverse tasks and stimuli to heighten activity of the brain should be carried out. PMID:28210035

Effects of observation of hand movements reflected in a mirror on cortical activation in patients with stroke.

PubMed

Chang, Moon-Young; Kim, Hwan-Hee; Kim, Kyeong-Mi; Oh, Jae-Seop; Jang, Chel; Yoon, Tae-Hyung

2017-01-01

[Purpose] The purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention. [Subjects and Methods] The subjects of this study were 14 patients with stroke (6 females and 8 males). The subjects were assessed by measuring the alpha and beta waves of the EEG (QEEG-32 system CANS 3000). The mirror therapy intervention was delivered over the course of four weeks (a total of 20 sessions). [Results] Relative alpha power showed statistically significant differences in the F3, F4, O1, and O2 channels in the situation comparison and higher for hand observation than for mirror observation. Relative beta power showed statistically significant differences in the F3, F4, C3, and C4 channels. [Conclusion] This study analyzed activity of the brain in each area when patients with stroke observed movements reflected in a mirror, and future research on diverse tasks and stimuli to heighten activity of the brain should be carried out.

Quantum Hamiltonian identification from measurement time traces.

PubMed

Zhang, Jun; Sarovar, Mohan

2014-08-22

Precise identification of parameters governing quantum processes is a critical task for quantum information and communication technologies. In this Letter, we consider a setting where system evolution is determined by a parametrized Hamiltonian, and the task is to estimate these parameters from temporal records of a restricted set of system observables (time traces). Based on the notion of system realization from linear systems theory, we develop a constructive algorithm that provides estimates of the unknown parameters directly from these time traces. We illustrate the algorithm and its robustness to measurement noise by applying it to a one-dimensional spin chain model with variable couplings.

Nonword Repetition Priming in Lexical Decision Reverses as a Function of Study Task and Speed Stress

ERIC Educational Resources Information Center

Zeelenberg, Rene; Wagenmakers, Eric-Jan; Shiffrin, Richard M.

2004-01-01

The authors argue that nonword repetition priming in lexical decision is the net result of 2 opposing processes. First, repeating nonwords in the lexical decision task results in the storage of a memory trace containing the interpretation that the letter string is a nonword; retrieval of this trace leads to an increase in performance for repeated…

EEG Dynamics Reflect the Distinct Cognitive Process of Optic Problem Solving

PubMed Central

She, Hsiao-Ching; Jung, Tzyy-Ping; Chou, Wen-Chi; Huang, Li-Yu; Wang, Chia-Yu; Lin, Guan-Yu

2012-01-01

This study explores the changes in electroencephalographic (EEG) activity associated with the performance of solving an optics maze problem. College students (N = 37) were instructed to construct three solutions to the optical maze in a Web-based learning environment, which required some knowledge of physics. The subjects put forth their best effort to minimize the number of convexes and mirrors needed to guide the image of an object from the entrance to the exit of the maze. This study examines EEG changes in different frequency bands accompanying varying demands on the cognitive process of providing solutions. Results showed that the mean power of θ, α1, α2, and β1 significantly increased as the number of convexes and mirrors used by the students decreased from solution 1 to 3. Moreover, the mean power of θ and α1 significantly increased when the participants constructed their personal optimal solution (the least total number of mirrors and lens used by students) compared to their non-personal optimal solution. In conclusion, the spectral power of frontal, frontal midline and posterior theta, posterior alpha, and temporal beta increased predominantly as the task demands and task performance increased. PMID:22815800

On-ground calibration of the ART-XC/SRG mirror system and detector unit at IKI. Part I

NASA Astrophysics Data System (ADS)

Pavlinsky, M.; Tkachenko, A.; Levin, V.; Krivchenko, A.; Rotin, A.; Kuznetsova, M.; Lapshov, I.; Krivonos, R.; Semena, A.; Semena, N.; Serbinov, D.; Shtykovsky, A.; Yaskovich, A.; Oleinikov, V.; Glushenko, A.; Mereminskiy, I.; Molkov, S.; Sazonov, S.; Arefiev, V.

2018-05-01

From October 2016 to September 2017, we performed tests of the ART-XC /SRG spare mirror system and detector unit at the 60-m-long IKI X-ray test facility. We describe some technical features of this test facility. We also present a brief description of the ART-XC mirror system and focal detectors. The nominal focal length of the ART-XC optics is 2700 mm. The field of view is determined by the combination of the mirror system and the detector unit and is equal to ˜0.31 square degrees. The declared operating energy range is 5-30 keV. During the tests, we illuminated the detector with a 55Fe+241 Am calibration source and also with a quasi-parallel X-ray beam. The calibration source is integrated into the detector's collimator. The X-ray beam was generated by a set of Oxford Instruments X-ray tubes with Cr, Cu and Mo targets and an Amptek miniature X-ray tube (Mini-X) with Ag transmission target. The detector was exposed to the X-ray beam either directly or through the mirror system. We present the obtained results on the detector's energy resolution, the muon on-ground background level and the energy dependence of the W90 value. The accuracy of a mathematical model of the ART-XC mirror system, based on ray-tracing simulations, proves to be within 3.5% in the main energy range of 4-20 keV and 5.4% in the "hard" energy range of 20-40 keV.

Simulations of far-field optical beam quality influenced by the thermal distortion of the secondary mirror for high-power laser system

NASA Astrophysics Data System (ADS)

Guo, Ruhai; Chen, Ning; Zhuang, Xinyu; Wang, Bing

2015-02-01

In order to research the influence on the beam quality due to thermal deformation of the secondary mirror in the high power laser system, the theoretical simulation study is performed. Firstly, three typical laser power 10kW, 50kW and 100kW with the wavelength 1.064μm are selected to analyze thermal deformation of mirror through the finite element analyze of thermodynamics instantaneous method. Then the wavefront aberration can be calculated by ray-tracing theory. Finally, focus spot radius，beam quality (BQ) of far-filed beam can be calculated and comparably analyzed by Fresnel diffraction integration. The simulation results show that with the increasing laser power, the optical aberration of beam director gets worse, the far-field optical beam quality decrease, which makes the laser focus spot broadening and the peak optical intensity of center decreasing dramatically. Comparing the clamping ring and the three-point clamping, the former is better than the latter because the former only induces the rotation symmetric deformation and the latter introduces additional astigmatism. The far-field optical beam quality can be improved partly by simply adjusting the distance between the main mirror and the secondary mirror. But the far-field power density is still the one tenth as that without the heat distortion of secondary mirror. These results can also provide the reference to the thermal aberration analyze for high power laser system and can be applied to the field of laser communication system and laser weapon etc.

Does abnormal interhemispheric inhibition play a role in mirror dystonia?

PubMed

Sattler, Virginie; Dickler, Maya; Michaud, Martin; Meunier, Sabine; Simonetta-Moreau, Marion

2014-05-01

The presence of mirror dystonia (dystonic movement induced by a specific task performed by the unaffected hand) in the dominant hand of writer's cramp patients when the nondominant hand is moved suggests an abnormal interaction between the 2 hemispheres. In this study we compare the level of interhemispheric inhibition (IHI) in 2 groups of patients with writer's cramp, one with the presence of a mirror dystonia and the other without as well as a control group. The level of bidirectional IHI was measured in wrist muscles with dual-site transcranial magnetic stimulation with a 10-millisecond (short IHI) and a 40-millisecond (long IHI) interstimulus interval during rest and while holding a pen in 9 patients with mirror dystonia 7 without mirror dystonia, and 13 controls. The group of patients without mirror dystonia did not differ from the controls in their IHI level. In contrast, IHI was significantly decreased in the group of patients with mirror dystonia in comparison with the group without mirror dystonia and the controls in both wrist muscles of both the dystonic and unaffected hand whatever the resting or active condition (P = 0.001). The decrease of IHI level in the group of patients with mirror dystonia was negatively correlated with the severity and the duration of the disease: the weaker the level of IHI, the more severe was the disease and the longer its duration. Interhemispheric inhibition disturbances are most likely involved in the occurrence of mirror dystonia. This bilateral deficient inhibition further suggests the involvement of the unaffected hemisphere in the pathophysiology of unilateral dystonia. © 2013 International Parkinson and Movement Disorder Society.

Matlab fractal techniques used to study the structural degradation caused by alpha radiation to laser mirrors

NASA Astrophysics Data System (ADS)

Ioan, M.-R.

2018-01-01

Almost all optical diagnostic systems associated with classical particle accelerators or with new state-of-the-art particle accelerators, such as those developed within the European Collaboration ELI-NP (Extreme Light Infrastructure-Nuclear Physics) (involving extreme power laser beams), contain in their infrastructure high quality laser mirrors, used for their reflectivity and/or their partial transmittance. These high quality mirrors facilitate the extraction and handling of optical signals. When optical mirrors are exposed to high energy ionizing radiation fields, their optical and structural properties will change over time and their functionality will be affected, meaning that they will provide imprecise information. In some experiments, being exposed to mixed laser and accelerated particle beams, the deterioration of laser mirrors is even more acute, since the destruction mechanisms of both types of beams are cumulated. The main task of the work described in this paper was to find a novel specific method to analyse and highlight such degradation processes. By using complex fractal techniques integrated in a MATLAB code, the effects induced by alpha radiation to laser mirrors were studied. The fractal analysis technique represents an alternative approach to the classical Euclidean one. It can be applied for the characterization of the defects occurred in mirrors structure due to their exposure to high energy alpha particle beams. The proposed method may be further integrated into mirrors manufacturing process, as a testing instrument, to obtain better quality mirrors (enhanced resistance to high energy ionizing beams) by using different types of reflective coating materials and different deposition techniques. Moreover, the effect of high energy alpha ionizing particles on the optical properties of the exposed laser mirrors was studied by using spectrophotometric techniques.

Aberrant within- and between-network connectivity of the mirror neuron system network and the mentalizing network in first episode psychosis.

PubMed

Choe, Eugenie; Lee, Tae Young; Kim, Minah; Hur, Ji-Won; Yoon, Youngwoo Bryan; Cho, Kang-Ik K; Kwon, Jun Soo

2018-03-26

It has been suggested that the mentalizing network and the mirror neuron system network support important social cognitive processes that are impaired in schizophrenia. However, the integrity and interaction of these two networks have not been sufficiently studied, and their effects on social cognition in schizophrenia remain unclear. Our study included 26 first-episode psychosis (FEP) patients and 26 healthy controls. We utilized resting-state functional connectivity to examine the a priori-defined mirror neuron system network and the mentalizing network and to assess the within- and between-network connectivities of the networks in FEP patients. We also assessed the correlation between resting-state functional connectivity measures and theory of mind performance. FEP patients showed altered within-network connectivity of the mirror neuron system network, and aberrant between-network connectivity between the mirror neuron system network and the mentalizing network. The within-network connectivity of the mirror neuron system network was noticeably correlated with theory of mind task performance in FEP patients. The integrity and interaction of the mirror neuron system network and the mentalizing network may be altered during the early stages of psychosis. Additionally, this study suggests that alterations in the integrity of the mirror neuron system network are highly related to deficient theory of mind in schizophrenia, and this problem would be present from the early stage of psychosis. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhancing the mirror illusion with transcranial direct current stimulation.

PubMed

Jax, Steven A; Rosa-Leyra, Diana L; Coslett, H Branch

2015-05-01

Visual feedback has a strong impact on upper-extremity movement production. One compelling example of this phenomena is the mirror illusion (MI), which has been used as a treatment for post-stroke movement deficits (mirror therapy). Previous research indicates that the MI increases primary motor cortex excitability, and this change in excitability is strongly correlated with the mirror's effects on behavioral performance of neurologically-intact controls. Based on evidence that primary motor cortex excitability can also be increased using transcranial direct current stimulation (tDCS), we tested whether bilateral tDCS to the primary motor cortices (anode right-cathode left and anode left-cathode right) would modify the MI. We measured the MI using a previously-developed task in which participants make reaching movements with the unseen arm behind a mirror while viewing the reflection of the other arm. When an offset in the positions of the two limbs relative to the mirror is introduced, reaching errors of the unseen arm are biased by the reflected arm's position. We found that active tDCS in the anode right-cathode left montage increased the magnitude of the MI relative to sham tDCS and anode left-cathode right tDCS. We take these data as a promising indication that tDCS could improve the effect of mirror therapy in patients with hemiparesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Divided multimodal attention sensory trace and context coding strategies in spatially congruent auditory and visual presentation.

PubMed

Kristjánsson, Tómas; Thorvaldsson, Tómas Páll; Kristjánsson, Arni

2014-01-01

Previous research involving both unimodal and multimodal studies suggests that single-response change detection is a capacity-free process while a discriminatory up or down identification is capacity-limited. The trace/context model assumes that this reflects different memory strategies rather than inherent differences between identification and detection. To perform such tasks, one of two strategies is used, a sensory trace or a context coding strategy, and if one is blocked, people will automatically use the other. A drawback to most preceding studies is that stimuli are presented at separate locations, creating the possibility of a spatial confound, which invites alternative interpretations of the results. We describe a series of experiments, investigating divided multimodal attention, without the spatial confound. The results challenge the trace/context model. Our critical experiment involved a gap before a change in volume and brightness, which according to the trace/context model blocks the sensory trace strategy, simultaneously with a roaming pedestal, which should block the context coding strategy. The results clearly show that people can use strategies other than sensory trace and context coding in the tasks and conditions of these experiments, necessitating changes to the trace/context model.

Ray tracing method for the evaluation of grazing incidence x-ray telescopes described by spatially sampled surfaces.

PubMed

Yu, Jun; Shen, Zhengxiang; Sheng, Pengfeng; Wang, Xiaoqiang; Hailey, Charles J; Wang, Zhanshan

2018-03-01

The nested grazing incidence telescope can achieve a large collecting area in x-ray astronomy, with a large number of closely packed, thin conical mirrors. Exploiting the surface metrological data, the ray tracing method used to reconstruct the shell surface topography and evaluate the imaging performance is a powerful tool to assist iterative improvement in the fabrication process. However, current two-dimensional (2D) ray tracing codes, especially when utilized with densely sampled surface shape data, may not provide sufficient accuracy of reconstruction and are computationally cumbersome. In particular, 2D ray tracing currently employed considers coplanar rays and thus simulates only these rays along the meridional plane. This captures axial figure errors but leaves other important errors, such as roundness errors, unaccounted for. We introduce a semianalytic, three-dimensional (3D) ray tracing approach for x-ray optics that overcomes these shortcomings. And the present method is both computationally fast and accurate. We first introduce the principles and the computational details of this 3D ray tracing method. Then the computer simulations of this approach compared to 2D ray tracing are demonstrated, using an ideal conic Wolter-I telescope for benchmarking. Finally, the present 3D ray tracing is used to evaluate the performance of a prototype x-ray telescope fabricated for the enhanced x-ray timing and polarization mission.

Eye Movement Patterns for Novice Teen Drivers Does 6 Months of Driving Experience Make a Difference?

PubMed Central

Olsen, Erik C. B.; Lee, Suzanne E.; Simons-Morton, Bruce G.

2009-01-01

Attention to the road is essential to safe driving, but the development of appropriate eye glance scanning behaviors may require substantial driving experience. Novice teen drivers may focus almost exclusively on the road ahead rather than scanning the mirrors, and when performing secondary tasks, they may spend more time with eyes on the task than on the road. This paper examines the extent to which the scanning of novice teens improves with experience. For this study, 18 novice teen (younger than 17.5 years old) and 18 experienced adult drivers performed a set of in-vehicle tasks and a baseline driving segment on a test track, the teens within 4 weeks of licensure and then again 6 months later. This paper addresses the following questions: Did teen eye glance performance improve from initial assessment? Did teens and adults still differ after 6 months? Results for some tasks showed that rearview and left mirror–window (LM-W) glances improved for teens from initial testing to the 6-month follow-up and that some differences between teens and adults at initial testing were no longer significant at the 6-month follow-up, suggesting significant learning effects. The frequency of rearview and LM-W glances during secondary tasks improved among teens at the 6-month follow-up, but teens still had significantly fewer glances to mirrors than did adults when engaged in a secondary task. PMID:19763225

Mirror neuron system and observational learning: behavioral and neurophysiological evidence.

PubMed

Lago-Rodriguez, Angel; Lopez-Alonso, Virginia; Fernández-del-Olmo, Miguel

2013-07-01

Three experiments were performed to study observational learning using behavioral, perceptual, and neurophysiological data. Experiment 1 investigated whether observing an execution model, during physical practice of a transitive task that only presented one execution strategy, led to performance improvements compared with physical practice alone. Experiment 2 investigated whether performing an observational learning protocol improves subjects' action perception. In experiment 3 we evaluated whether the type of practice performed determined the activation of the Mirror Neuron System during action observation. Results showed that, compared with physical practice, observing an execution model during a task that only showed one execution strategy does not provide behavioral benefits. However, an observational learning protocol allows subjects to predict more precisely the outcome of the learned task. Finally, intersperse observation of an execution model with physical practice results in changes of primary motor cortex activity during the observation of the motor pattern previously practiced, whereas modulations in the connectivity between primary and non primary motor areas (PMv-M1; PPC-M1) were not affected by the practice protocol performed by the observer. Copyright © 2013 Elsevier B.V. All rights reserved.

Cognitive Control Structures in the Imitation Learning of Spatial Sequences and Rhythms-An fMRI Study.

PubMed

Sakreida, Katrin; Higuchi, Satomi; Di Dio, Cinzia; Ziessler, Michael; Turgeon, Martine; Roberts, Neil; Vogt, Stefan

2018-03-01

Imitation learning involves the acquisition of novel motor patterns based on action observation (AO). We used event-related functional magnetic resonance imaging to study the imitation learning of spatial sequences and rhythms during AO, motor imagery (MI), and imitative execution in nonmusicians and musicians. While both tasks engaged the fronto-parietal mirror circuit, the spatial sequence task recruited posterior parietal and dorsal premotor regions more strongly. The rhythm task involved an additional network for auditory working memory. This partial dissociation supports the concept of task-specific mirror mechanisms. Two regions of cognitive control were identified: 1) dorsolateral prefrontal cortex (DLPFC) was found to be more strongly activated during MI of novel spatial sequences, which allowed us to extend the 2-level model of imitation learning by Buccino et al. (2004) to spatial sequences. 2) During imitative execution of both tasks, the posterior medial frontal cortex was robustly activated, along with the DLPFC, which suggests that both regions are involved in the cognitive control of imitation learning. The musicians' selective behavioral advantage for rhythm imitation was reflected cortically in enhanced sensory-motor processing during AO and by the absence of practice-related activation differences in DLPFC during rhythm execution. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Windmill-task as a New Quantitative and Objective Assessment for Mirror Movements in Unilateral Cerebral Palsy: A Pilot Study.

PubMed

Zielinski, Ingar Marie; Steenbergen, Bert; Schmidt, Anna; Klingels, Katrijn; Simon Martinez, Cristina; de Water, Pascal; Hoare, Brian

2018-03-23

To introduce the Windmill-task, a new objective assessment tool to quantify the presence of mirror movements (MMs) in children with unilateral cerebral palsy (UCP), which are typically assessed with the observation-based Woods and Teuber scale (W&T). Prospective, observational, cohort pilot study. Children's hospital. Prospective cohort of children (N=23) with UCP (age range, 6-15y, mean age, 10.5±2.7y). Not applicable. The concurrent validity of the Windmill-task is assessed, and the sensitivity and specificity for MM detection are compared between both assessments. To assess the concurrent validity, Windmill-task data are compared with W&T data using Spearman rank correlations (ρ) for 2 conditions: affected hand moving vs less affected hand moving. Sensitivity and specificity are compared by measuring the mean percentage of children being assessed inconsistently across both assessments. Outcomes of both assessments correlated significantly (affected hand moving: ρ=.520; P=.005; less affected hand moving: ρ=.488; P=.009). However, many children displayed MMs on the Windmill-task, but not on the W&T (sensitivity: affected hand moving: 27.5%; less affected hand moving: 40.6%). Only 2 children displayed MMs on the W&T, but not on the Windmill-task (specificity: affected hand moving: 2.9%; less affected hand moving: 1.4%). The Windmill-task seems to be a valid tool to assess MMs in children with UCP and has an additional advantage of sensitivity to detect MMs. Copyright © 2018 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

No evidence for mirror system dysfunction in schizophrenia from a multimodal TMS/EEG study.

PubMed

Andrews, Sophie C; Enticott, Peter G; Hoy, Kate E; Thomson, Richard H; Fitzgerald, Paul B

2015-08-30

Dysfunctional mirror neuron systems have been proposed to contribute to the social cognitive deficits observed in schizophrenia. A few studies have explored mirror systems in schizophrenia using various techniques such as TMS (levels of motor resonance) or EEG (levels of mu suppression), with mixed results. This study aimed to use a novel multimodal approach (i.e. concurrent TMS and EEG) to further investigate mirror systems and social cognition in schizophrenia. Nineteen individuals with schizophrenia or schizoaffective disorder and 19 healthy controls participated. Single-pulse TMS was applied to M1 during the observation of hand movements designed to elicit mirror system activity. Single EEG electrodes (C3, CZ, C4) recorded brain activity. Participants also completed facial affect recognition and theory of mind tasks. The schizophrenia group showed significant deficits in facial affect recognition and higher level theory of mind compared to healthy controls. A significant positive relationship was revealed between mu suppression and motor resonance for the overall sample, indicating concurrent validity of these measures. Levels of mu suppression and motor resonance were not significantly different between groups. These findings indicate that in stable outpatients with schizophrenia, mirror system functioning is intact, and therefore their social cognitive difficulties may be caused by alternative pathophysiology. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Adolescent and Adult Rats Differ in the Amnesic Effects of Acute Ethanol in Two Hippocampus-Dependent Tasks: Trace and Contextual Fear Conditioning

PubMed Central

Hunt, Pamela S.; Barnet, Robert C.

2015-01-01

Experience-produced deficits in trace conditioning and context conditioning have been useful tools for examining the role of the hippocampus in learning. It has also been suggested that learning in these tasks is especially vulnerable to neurotoxic effects of alcohol during key developmental periods such as adolescence. In five experiments we systematically examined the presence and source of age-dependent vulnerability to the memory-disrupting effects of acute ethanol in trace conditioning and contextual fear conditioning. In Experiment 1a pre-training ethanol disrupted trace conditioning more strongly in adolescent (postnatal day, PD30-35) than adult rats (PD65-75). In Experiment 1b when pre-training ethanol was accompanied by pre-test ethanol no deficit in trace conditioning was observed in adolescents, suggesting that state-dependent retrieval failure mediated ethanol's disruption of trace conditioning at this age. Experiments 2a and 2b examined the effect of ethanol pretreatment on context conditioning. Here, adult but not adolescent rats were impaired in conditioned freezing to context cues. Experiment 2c explored state-dependency of this effect. Pre-training ethanol continued to disrupt context conditioning in adults even when ethanol was also administered prior to test. Collectively these findings reveal clear age-dependent and task-dependent vulnerabilities in ethanol's disruptive effects on hippocampus-dependent memory. Adolescents were more disrupted by ethanol in trace conditioning than adults, and adults were more disrupted by ethanol in context conditioning than adolescents. We suggest that adolescents may be more susceptible to changes in internal state (state-dependent retrieval failure) than adults and that ethanol disrupted performance in trace and context conditioning through different mechanisms. Relevance of these findings to theories of hippocampus function is discussed. PMID:26192910

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

Lee, Gregory L.; Arnold, Dorian; LeGendre, Matthew

STAT is a light weight debugging tool that gathers and merges stack traces from all of the processes in a parallel application. STAT uses the MRNet tree based overlay network to broadcast commands from the tool front-end to the STAT daemons and for the front-end to gather the traces from the STAT daemons. As the traces propagate through the MRNet network tree, they are merged across all tasks to form a similar function call patterns and to delineate a small set of equivalence classes. A representative task from each of these classes can then be fed into a full featuremore » debugger like TolalView for root cause analysis.« less

Methods for reducing ghost rays on the Wolter-I focusing figures of the FOXSI rocket payload

NASA Astrophysics Data System (ADS)

Buitrago-Casas, Juan Camilo; Glesener, Lindsay; Christe, Steven; Ramsey, Brian; Elsner, Ronald; Courtade, Sasha; Vievering, Juliana; Subramania, Athiray; Krucker, Sam; Bale, Stuart

2017-08-01

In high energy solar astrophysics, imaging hard X-rays by direct focusing offers higher dynamic range and greater sensitivity compared to past techniques that used indirect imaging. The Focusing Optics X-ray Solar Imager (FOXSI) is a sounding rocket payload which uses seven sets of nested Wolter-I figured mirrors that, together with seven high-sensitive semiconductor detectors, observes the Sun in hard X-rays by direct focusing. The FOXSI rocket has successfully flown twice and is funded to fly a third time in summer 2018.The Wolter-I geometry consists of two consecutive mirrors, one paraboloid, and one hyperboloid, that reflect photons at grazing angles. Correctly focused X-rays reflect twice, once per mirror segment. For extended sources, like the Sun, off-axis photons at certain incident angles can reflect on only one mirror and still reach the focal plane, generating a pattern of single-bounce photons, or ‘ghost rays’ that can limit the sensitivity of the observation of focused X-rays. Understanding and cutting down the ghost rays on the FOXSI optics will maximize the instrument’s sensitivity of the solar faintest sources for future flights. We present an analysis of the FOXSI ghost rays based on ray-tracing simulations, as well as the effectiveness of different physical strategies to reduce them.

Generalized design of a zero-geometric-loss, astigmatism-free, modified four-objective multipass matrix system.

PubMed

Guo, Yin; Sun, LiQun; Yang, Zheng; Liu, Zilong

2016-02-20

During this study we constructed a generalized parametric modified four-objective multipass matrix system (MMS). We used an optical system comprising four asymmetrical spherical mirrors to improve the alignment process. The use of a paraxial equation for the design of the front transfer optics yielded the initial condition for modeling our MMS. We performed a ray tracing simulation to calculate the significant aberration of the system (astigmatism). Based on the calculated meridional and sagittal focus positions, the complementary focusing mirror was easily designed to provide an output beam free of astigmatism. We have presented an example of a 108-transit multipass system (5×7 matrix arrangement) with a relatively larger numerical aperture source (xenon light source). The whole system exhibits zero theoretical geometrical loss when simulated with Zemax software. The MMS construction strategy described in this study provides an anastigmatic output beam and the generalized approach to design a controllable matrix spot pattern on the field mirrors. Asymmetrical reflective mirrors aid in aligning the whole system with high efficiency. With the generalized design strategy in terms of optics configuration and asymmetrical fabrication method in this paper, other kinds of multipass matrix system coupled with different sources and detector systems also can be achieved.

Methods for Reducing Singly Reflected Rays on the Wolter-I Focusing Figures of the FOXSI Rocket Experiment

NASA Technical Reports Server (NTRS)

Buitrago-Casas, Juan Camilo; Glesener, Lindsay; Christe, Steven; Elsner, Ronald; Ramsey, Brian; Courtade, Sasha; Ishikawa, Shin-nosuke; Narukage, Noriyuki; Vievering, Juliana; Subramania, Athiray;

Flat-field anastigmatic mirror objective for high-magnification extreme ultraviolet microscopy

NASA Astrophysics Data System (ADS)

Toyoda, Mitsunori

2015-08-01

To apply high-definition microscopy to the extreme ultraviolet (EUV) region in practice, i.e. to enable in situ observation of living tissue and the at-wavelength inspection of lithography masks, we constructed a novel reflective objective made of three multilayer mirrors. This objective is configured as a two-stage imaging system made of a Schwarzschild two-mirror system as the primary objective and an additional magnifier with a single curved mirror. This two-stage configuration can provide a high magnification of 1500, which is suitable for real-time observation with an EUV charge coupled device (CCD) camera. Besides, since off-axis aberrations can be corrected by the magnifier, which provides field flattener optics, we are able to configure the objective as a flat-field anastigmatic system, in which we will have a diffraction-limited spatial resolution over a large field-of-view. This paper describes in detail the optical design of the present objective. After calculating the closed-form equations representing the third-order aberrations of the objective, we apply these equations to practical design examples with a numerical aperture of 0.25 and an operation wavelength of 13.5 nm. We also confirm the imaging performances of this novel design by using the numerical ray-tracing method.

Kinematic parameters of hand movement during a disparate bimanual movement task in children with unilateral Cerebral Palsy.

PubMed

Rudisch, Julian; Butler, Jenny; Izadi, Hooshang; Zielinski, Ingar Marie; Aarts, Pauline; Birtles, Deirdre; Green, Dido

2016-04-01

Children with unilateral Cerebral Palsy (uCP) experience problems performing tasks requiring the coordinated use of both hands (bimanual coordination; BC). Additionally, some children with uCP display involuntary symmetrical activation of the opposing hand (mirrored movements). Measures, used to investigate therapy-related improvements focus on the functionality of the affected hand during unimanual or bimanual tasks. None however specifically address spatiotemporal integration of both hands. We explored the kinematics of hand movements during a bimanual task to identify parameters of BC. Thirty-seven children (aged 10.9±2.6years, 20 male) diagnosed with uCP participated. 3D kinematic motion analysis was performed during the task requiring opening of a box with their affected- (AH) or less-affected hand (LAH), and pressing a button inside with the opposite hand. Temporal and spatial components of data were extracted and related to measures of hand function and level of impairment. Total task duration was correlated with the Jebsen-Taylor Test of Hand Function in both conditions (either hand leading with the lid-opening). Spatial accuracy of the LAH when the box was opened with their AH was correlated with outcomes on the Children's Hand Use Experience Questionnaire. Additionally, we found a subgroup of children displaying non-symmetrical movement interference associated with greater movement overlap when their affected hand opened the box. This subgroup also demonstrated decreased use of the affected hand during bimanual tasks. Further investigation of bimanual interference, which goes beyond small scaled symmetrical mirrored movements, is needed to consider its impact on bimanual task performance following early unilateral brain injury. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Kim, Jungho; Shi, Xianbo; Casa, Diego

Advances in resonant inelastic X-ray scattering (RIXS) have come in lockstep with improvements in energy resolution. Currently, the best energy resolution at the IrL 3-edge stands at ~25 meV, which is achieved using a diced Si(844) spherical crystal analyzer. However, spherical analyzers are limited by their intrinsic reflection width. A novel analyzer system using multiple flat crystals provides a promising way to overcome this limitation. For the present design, an energy resolution at or below 10 meV was selected. Recognizing that the angular acceptance of flat crystals is severely limited, a collimating element is essential to achieve the necessary solid-anglemore » acceptance. For this purpose, a laterally graded, parabolic, multilayer Montel mirror was designed for use at the IrL 3-absorption edge. It provides an acceptance larger than 10 mrad, collimating the reflected X-ray beam to smaller than 100 µrad, in both vertical and horizontal directions. The performance of this mirror was studied at beamline 27-ID at the Advanced Photon Source. X-rays from a diamond (111) monochromator illuminated a scattering source of diameter 5 µm, generating an incident beam on the mirror with a well determined divergence of 40 mrad. A flat Si(111) crystal after the mirror served as the divergence analyzer. From X-ray measurements, ray-tracing simulations and optical metrology results, it was established that the Montel mirror satisfied the specifications of angular acceptance and collimation quality necessary for a high-resolution RIXS multi-crystal analyzer system.« less

Design and manufacture of the integrated field unit for the NIRSpec spectrometer on JWST

NASA Astrophysics Data System (ADS)

Lobb, Daniel; Robertson, David; Closs, Martin; Barnes, Andy

2008-09-01

The NIRSpec imaging spectrometer, which forms part of the James Webb Space Telescope instrumentation, will include an integrated field unit (IFU). The IFU will be tasked specifically with efficient analysis of extended objects, including galaxies; it will accept a square image area at the spectrometer entrance field, dissect this area into 30 parallel sub-slits, and image the sub-slits end-to-end, forming a single virtual entrance slit. The IFU, uses all-mirror optics to operate over the spectral range 700nm to 5000nm. 95 mirrors and the main support structure are made in a common aluminium alloy, to achieve athermal performance down to an operating temperature of around 30K. Relatively complex mirror surface shapes are produced by diamond machining. The IFU has been designed and constructed by SSTL, with optics produced by CfAI; the unit is currently undergoing performance tests. This paper describes the IFU optical design and performance, and outlines the mirror manufacturing methods and alignment procedures.

Elephants know when their bodies are obstacles to success in a novel transfer task

PubMed Central

Dale, Rachel; Plotnik, Joshua M.

2017-01-01

The capacity to recognise oneself as separate from other individuals and objects is difficult to investigate in non-human animals. The hallmark empirical assessment, the mirror self-recognition test, focuses on an animal’s ability to recognise itself in a mirror and success has thus far been demonstrated in only a small number of species with a keen interest in their own visual reflection. Adapting a recent study done with children, we designed a new body-awareness paradigm for testing an animal’s understanding of its place in its environment. In this task, Asian elephants (Elephas maximus) were required to step onto a mat and pick up a stick attached to it by rope, and then pass the stick forward to an experimenter. In order to do the latter, the elephants had to see their body as an obstacle to success and first remove their weight from the mat before attempting to transfer the stick. The elephants got off the mat in the test significantly more often than in controls, where getting off the mat was unnecessary. This task helps level the playing field for non-visual species tested on cognition tasks and may help better define the continuum on which body- and self-awareness lie. PMID:28402335

Optical simulations of laser focusing for optimization of laser betatron

NASA Astrophysics Data System (ADS)

Stanke, L.; Thakur, A.; Šmíd, M.; Gu, Y. J.; Falk, K.

2017-05-01

This work presents optical simulations that are used to design a betatron driven by a short-pulse laser based on the Laser Wakefield Acceleration (LWFA) concept. These simulations explore how the optical setup and its components influence the performance of the betatron. The impact of phase irregularities induced by optical elements is investigated. In order to obtain a good estimate of the future performance of this design a combination of two distinct techniques are used - Field Tracing for optical simulations employing a combination of the Zemax and VirtualLab computational platforms for the laser beam propagation and focusing with the given optical system and particle-in-cell simulation (PIC) for simulating the short-pulse laser interaction with a gas target. The result of the optical simulations serves as an input for the PIC simulations. Application of Field Tracing in combination with the PIC for the purposes of high power laser facility introduces the new application for VirtualLab Fusion. Based on the result of these simulations an alternative design with a hole in the final folding mirror coupled with a spherical focusing mirror is considered in favour of more commonly used off-axis parabola focusing setup. Results are demonstrating, that the decrease of the irradiance due to the presence of the central hole in the folding mirror is negligible (9.69× 1019 W/cm2 for the case without the hole vs. 9.73× 1019 W/cm2 for the case with hole). However, decrease caused by the surface irregularities (surface RMS λ/4 , λ/20 and λ/40 ) is more significant and leads to the poor performance of particle production.

Biosonar navigation above water II: exploiting mirror images.

PubMed

Genzel, Daria; Hoffmann, Susanne; Prosch, Selina; Firzlaff, Uwe; Wiegrebe, Lutz

2015-02-15

As in vision, acoustic signals can be reflected by a smooth surface creating an acoustic mirror image. Water bodies represent the only naturally occurring horizontal and acoustically smooth surfaces. Echolocating bats flying over smooth water bodies encounter echo-acoustic mirror images of objects above the surface. Here, we combined an electrophysiological approach with a behavioral experimental paradigm to investigate whether bats can exploit echo-acoustic mirror images for navigation and how these mirrorlike echo-acoustic cues are encoded in their auditory cortex. In an obstacle-avoidance task where the obstacles could only be detected via their echo-acoustic mirror images, most bats spontaneously exploited these cues for navigation. Sonar ensonifications along the bats' flight path revealed conspicuous changes of the reflection patterns with slightly increased target strengths at relatively long echo delays corresponding to the longer acoustic paths from the mirrored obstacles. Recordings of cortical spatiotemporal response maps (STRMs) describe the tuning of a unit across the dimensions of elevation and time. The majority of cortical single and multiunits showed a special spatiotemporal pattern of excitatory areas in their STRM indicating a preference for echoes with (relative to the setup dimensions) long delays and, interestingly, from low elevations. This neural preference could effectively encode a reflection pattern as it would be perceived by an echolocating bat detecting an object mirrored from below. The current study provides both behavioral and neurophysiological evidence that echo-acoustic mirror images can be exploited by bats for obstacle avoidance. This capability effectively supports echo-acoustic navigation in highly cluttered natural habitats. Copyright © 2015 the American Physiological Society.

Patient-directed therapy during in-patient stroke rehabilitation: stroke survivors' views of feasibility and acceptability.

PubMed

Horne, Maria; Thomas, Nessa; McCabe, Candy; Selles, Rudd; Vail, Andy; Tyrrell, Pippa; Tyson, Sarah

2015-01-01

Patient-led therapy, in which patients work outside therapy sessions without direct supervision, is a possible way to increase the amount of therapy stroke patients' receive without increasing staff demands. Here, we report patients' views of patient-led mirror therapy and lower limb exercises. 94 stroke survivors with upper and lower limb limitations at least 1-week post-stroke undertook 4 weeks of daily patient-led mirror therapy or lower limb exercise, then completed questionnaires regarding their experience and satisfaction. A convenience random sample of 20 participants also completed a semi-structured telephone interview to consider their experience in more detail and to capture their longer term impressions. Participants were generally positive about patient-led therapy. About 71% found it useful; 68% enjoyed it; 59% felt it "worked" and 88% would recommend it to other patients. Exercise was viewed more positively than the mirror therapy. Difficulties included arranging the equipment and their position, particularly for more severe strokes, loss of motivation and concerns about working unsupervised. Patient-led mirror therapy and lower limb exercises during in-patient rehabilitation is generally feasible and acceptable to patients but "light touch" supervision to deal with any problems, and strategies to maintain focus and motivation are needed. Implications for Rehabilitation Most stroke patients receive insufficient therapy to maximize recovery during rehabilitation. As increases in staffing are unlikely there is an imperative to find ways for patients to increase the amount of exercise and practice of functional tasks they undertake without increasing demands on staff. Patient-led therapy (also known as patient-directed therapy or independent practice), in which patients undertake exercises or functional tasks practice prescribed by a professional outside formal therapy sessions is one way of achieving this. It is widely used in community-based rehabilitation but is uncommon in hospital-based stroke care. We explored the feasibility and acceptability of two types of patient-led therapy during hospital-based stroke care; mirror therapy for the upper limb and exercises (without a mirror) for the lower limb. Here, we report patients' experiences of undertaking patient-led therapy. Patient-led mirror therapy and lower limb exercises during in-patient stroke rehabilitation is generally feasible and acceptable to patients but "light touch" supervision to deal with any problems, and strategies to maintain focus and motivation are needed.

Sensitivity to perception level differentiates two subnetworks within the mirror neuron system.

PubMed

Simon, Shiri; Mukamel, Roy

2017-05-01

Mirror neurons are a subset of brain cells that discharge during action execution and passive observation of similar actions. An open question concerns the functional role of their ability to match observed and executed actions. Since understanding of goals requires conscious perception of actions, we expect that mirror neurons potentially involved in action goal coding, will be modulated by changes in action perception level. Here, we manipulated perception level of action videos depicting short hand movements and measured the corresponding fMRI BOLD responses in mirror regions. Our results show that activity levels within a network of regions, including the sensorimotor cortex, primary motor cortex, dorsal premotor cortex and posterior superior temporal sulcus, are sensitive to changes in action perception level, whereas activity levels in the inferior frontal gyrus, ventral premotor cortex, supplementary motor area and superior parietal lobule are invariant to such changes. In addition, this parcellation to two sub-networks manifest as smaller functional distances within each group of regions during task and resting state. Our results point to functional differences between regions within the mirror neurons system which may have implications with respect to their possible role in action understanding. © The Author (2017). Published by Oxford University Press.

Surface finish quality of the outer AXAF mirror pair based on x ray measurements of the VETA-I

NASA Technical Reports Server (NTRS)

Hughes, John P.; Schwartz, Daniel A.; Szentgyorgyi, Andrew; Vanspeybroeck, Leon; Zhao, Ping

1992-01-01

We employ the X-ray measurements of the VETA-I taken at the X-Ray Calibration Facility (XRCF) of the Marshall Space Flight Center (MSFC) to extract information about the surface finish quality of the outermost pair of AXAF mirrors. The particular measurements we consider are one dimensional scans of the core of the point response function (PRF) (full width half maximum (FWHM) scans), the encircled energy as a function of radius, and one dimensional scans of the wings of the PRF. We discuss briefly our ray trace model which incorporates the numerous effects present in the VETA-I test, such as the finite source distance, the size and shape of the X-ray source, the residual gravitational distortions of the optic, the despace of the VETA-I, and particulate contamination. We show how the data constrain the amplitude of mirror surface deviations for spatial frequencies greater than about 0.1 mm(exp -1). Constraints on the average amplitude of circumferential slope errors are derived as well.

Polarization modeling and predictions for Daniel K. Inouye Solar Telescope part 1: telescope and example instrument configurations

NASA Astrophysics Data System (ADS)

Harrington, David M.; Sueoka, Stacey R.

2017-01-01

We outline polarization performance calculations and predictions for the Daniel K. Inouye Solar Telescope (DKIST) optics and show Mueller matrices for two of the first light instruments. Telescope polarization is due to polarization-dependent mirror reflectivity and rotations between groups of mirrors as the telescope moves in altitude and azimuth. The Zemax optical modeling software has polarization ray-trace capabilities and predicts system performance given a coating prescription. We develop a model coating formula that approximates measured witness sample polarization properties. Estimates show the DKIST telescope Mueller matrix as functions of wavelength, azimuth, elevation, and field angle for the cryogenic near infra-red spectro-polarimeter (CryoNIRSP) and visible spectro-polarimeter. Footprint variation is substantial and shows vignetted field points will have strong polarization effects. We estimate 2% variation of some Mueller matrix elements over the 5-arc min CryoNIRSP field. We validate the Zemax model by showing limiting cases for flat mirrors in collimated and powered designs that compare well with theoretical approximations and are testable with lab ellipsometers.

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

Meng, Xiangyu; Shi, Xianbo; Wang, Yong

The mutual optical intensity (MOI) model is extended to include the propagation of partially coherent radiation through non-ideal mirrors. The propagation of the MOI from the incident to the exit plane of the mirror is realised by local ray tracing. The effects of figure errors can be expressed as phase shifts obtained by either the phase projection approach or the direct path length method. Using the MOI model, the effects of figure errors are studied for diffraction-limited cases using elliptical cylinder mirrors. Figure errors with low spatial frequencies can vary the intensity distribution, redistribute the local coherence function and distortmore » the wavefront, but have no effect on the global degree of coherence. The MOI model is benchmarked againstHYBRIDand the multi-electronSynchrotron Radiation Workshop(SRW) code. The results show that the MOI model gives accurate results under different coherence conditions of the beam. Other than intensity profiles, the MOI model can also provide the wavefront and the local coherence function at any location along the beamline. The capability of tuning the trade-off between accuracy and efficiency makes the MOI model an ideal tool for beamline design and optimization.« less

The neuronal correlates of mirror illusion in children with spastic hemiparesis: a study with functional magnetic resonance imaging.

PubMed

Weisstanner, Christian; Saxer, Stefanie; Wiest, Roland; Kaelin-Lang, Alain; Newman, Christopher J; Steinlin, Maja; Grunt, Sebastian

2017-03-21

To investigate the neuronal activation pattern underlying the effects of mirror illusion in children/adolescents with normal motor development and in children/adolescents with hemiparesis and preserved contralateral corticospinal organisation. The type of cortical reorganisation was classified according to results of transcranial magnetic stimulation. Only subjects with congenital lesions and physiological contralateral cortical reorganisation were included. Functional magnetic resonance imaging was performed to investigate neuronal activation patterns with and without a mirror box. Each test consisted of a unimanual and a bimanual motor task. Seven children/adolescents with congenital hemiparesis (10-20 years old, three boys and four girls) and seven healthy subjects (8-17 years old, four boys and three girls) participated in this study. In the bimanual experiment, children with hemiparesis showed a significant effect of the mirror illusion (p<0.001 at voxel level, family-wise error corrected at cluster level) in the dorsolateral prefrontal cortex and anterior cingulate cortex of the affected and unaffected hemispheres, respectively. No significant effects of the mirror illusion were observed in unimanual experiments and in healthy participants. Mirror illusion in children/adolescents with hemiparesis leads to activation of brain areas involved in visual conflict detection and cognitive control to resolve this conflict. This effect is observed only in bimanual training. We consider that for mirror therapy in children and adolescents with hemiparesis a bimanual approach is more suitable than a unimanual approach.

Operation "Frontal Lobe" versus the "Living Room Toy": The Battle over Program Control in Early Television.

ERIC Educational Resources Information Center

Boddy, William

The development of the television industry in the United States as it emerged in the 1950s is mirrored by tracing the policies and actions of NBC (the National Broadcasting Company) during this period. As the leading radio network and as a subsidiary of RCA (the Radio Corporation of America), NBC was in a uniquely powerful position to direct the…

Calculation of the overlap factor for scanning LiDAR based on the tridimensional ray-tracing method.

PubMed

Chen, Ruiqiang; Jiang, Yuesong; Wen, Luhong; Wen, Donghai

2017-06-01

The overlap factor is used to evaluate the LiDAR light collection ability. Ranging LiDAR is mainly determined by the optical configuration. However, scanning LiDAR, equipped with a scanning mechanism to acquire a 3D coordinate points cloud for a specified target, is essential in considering the scanning effect at the same time. Otherwise, scanning LiDAR will reduce the light collection ability and even cannot receive any echo. From this point of view, we propose a scanning LiDAR overlap factor calculation method based on the tridimensional ray-tracing method, which can be applied to scanning LiDAR with any special laser intensity distribution, any type of telescope (reflector, refractor, or mixed), and any shape obstruction (i.e., the reflector of a coaxial optical system). A case study for our LiDAR with a scanning mirror is carried out, and a MATLAB program is written to analyze the laser emission and reception process. Sensitivity analysis is carried out as a function of scanning mirror rotation speed and detector position, and the results guide how to optimize the overlap factor for our LiDAR. The results of this research will have a guiding significance in scanning LiDAR design and assembly.

Development of Multi-Beam Long Trace Profiler

NASA Technical Reports Server (NTRS)

Kilaru, Kiranmayee; Merthe, Daniel J.; Ali, Zulfiqar; Gubarev, Mikhail V.; Kester, Thomas; McKinney, Wayne R.; Takacs, Peter Z.; Yashchuk, Valeriy V.

2011-01-01

In order to fulfill the angular resolution requirements and make the performance goals for future NASA missions feasible, it is crucial to develop instruments capable of fast and precise figure metrology of x-ray optical elements for further correction of the surface errors. The Long Trace Profilometer (LTP) is an instrument widely used for measuring the surface figure of grazing incidence X-ray mirrors. In the case of replicated optics designed for x-ray astronomy applications, such as mirrors and the corresponding mandrels have a cylindrical shape and their tangential profile is parabolic or hyperbolic. Modern LTPs have sub-microradian accuracy, but the measuring speed is very low, because the profilometer measures surface figure point by point using a single laser beam. The measurement rate can be significantly improved by replacing the single optical beam with multiple beams. The goal of this study is to demonstrate the viability of multi-beam metrology as a way of significantly improving the quality and affordability of replicated x-ray optics. The multi-beam LTP would allow one- and two-dimensional scanning with sub-microradian resolution and a measurement rate of about ten times faster compared to the current LTP. The design details of the instrument's optical layout and the status of optical tests will be presented.

Prism adaptation does not change the rightward spatial preference bias found with ambiguous stimuli in unilateral neglect

PubMed Central

Sarri, Margarita; Greenwood, Richard; Kalra, Lalit; Driver, Jon

2011-01-01

Previous research has shown that prism adaptation (prism adaptation) can ameliorate several symptoms of spatial neglect after right-hemisphere damage. But the mechanisms behind this remain unclear. Recently we reported that prisms may increase leftward awareness for neglect in a task using chimeric visual objects, despite apparently not affecting awareness in a task using chimeric emotional faces (Sarri et al., 2006). Here we explored potential reasons for this apparent discrepancy in outcome, by testing further whether the lack of a prism effect on the chimeric face task task could be explained by: i) the specific category of stimuli used (faces as opposed to objects); ii) the affective nature of the stimuli; and/or iii) the particular task implemented, with the chimeric face task requiring forced-choice judgements of lateral ‘preference’ between pairs of identical, but left/right mirror-reversed chimeric face tasks (as opposed to identification for the chimeric object task). We replicated our previous pattern of no impact of prisms on the emotional chimeric face task here in a new series of patients, while also similarly finding no beneficial impact on another lateral ‘preference’ measure that used non-face non-emotional stimuli, namely greyscale gradients. By contrast, we found the usual beneficial impact of prism adaptation (prism adaptation) on some conventional measures of neglect, and improvements for at least some patients in a different face task, requiring explicit discrimination of the chimeric or non-chimeric nature of face stimuli. The new findings indicate that prism therapy does not alter spatial biases in neglect as revealed by ‘lateral preference tasks’ that have no right or wrong answer (requiring forced-choice judgements on left/right mirror-reversed stimuli), regardless of whether these employ face or non-face stimuli. But our data also show that prism therapy can beneficially modulate some aspects of visual awareness in spatial neglect not only for objects, but also for face stimuli, in some cases. PMID:20171612

Rugged optical mirrors for the operation of Fourier-Transform Spectrometers in rough environments

NASA Astrophysics Data System (ADS)

Feist, Dietrich G.

2014-05-01

The Total Carbon Column Observing Network (TCCON) and the Network for the Detection of Atmospheric Composition Change (NDACC) operate a growing number of Fourier-Transform Spectrometers (FTS) that measure the total column of several atmospheric trace gases. For these measurements, the sun is used as a light source. This is typically achieved by a solar tracker that uses a pair of optical mirrors to guide the sunlight into the instrument. There is a growing demand to operate these instruments in remote locations that fill the gaps in the global observation network. Besides the logistical challenges of running a remote site, the environment at these locations can be very harsh compared to the sheltered environment of the instruments' home institutions. While the FTS itself is usually well protected inside a building or container, the solar tracker and especially its mirrors are exposed to the environment. There they may suffer from - temperature fluctuations - high humidity - sea salt corrosion at coastal sites - dirt and dust - air pollution from anthropogenic sources - deposition from plants or animals The Max Planck Institute for Biogeochemistry (MPI-BGC) operates a TCCON station on Ascension Island, about 200 m from the sea. Under the rough conditions at this site, typical optical mirrors that are made for laboratory conditions are destroyed by sea salt spray within a few weeks. Besides, typical gold-coated mirrors cannot be cleaned as their soft surface is easily scratched or damaged. To overcome these problems, the MPI-BGC has developed optical mirrors that - offer good reflectivity in the near and mid infrared - are highly resistant to salt and chlorine - have a hard surface so that they can be cleaned often and easily - are not affected by organic solvents - last for months in very harsh environments - can be reused after polishing These mirrors could be applied to most TCCON and NDACC sites. This way, the network could be expanded to regions where operation would have been too challenging so far.

Optical simulations for design, alignment, and performance prediction of silicon pore optics for the ATHENA x-ray telescope (Conference Presentation)

NASA Astrophysics Data System (ADS)

Spiga, D.; Della Monica Ferreira, D.; Shortt, B.; Bavdaz, M.; Bergback Knudsen, E.; Bianucci, G.; Christensen, F.; Civitani, M.; Collon, M.; Conconi, P.; Fransen, S.; Marioni, F.; Massahi, S.; Pareschi, G.; Salmaso, B.; Jegers, A. S.; Tayabaly, K.; Valsecchi, G.; Westergaard, N.; Wille, E.

2017-09-01

The ATHENA X-ray observatory is a large-class ESA approved mission, with launch scheduled in 2028. The technology of silicon pore optics (SPO) was selected as baseline to assemble ATHENA's optic with hundreds of mirror modules, obtained by stacking wedged and ribbed silicon wafer plates onto silicon mandrels to form the Wolter-I configuration. In the current configuration, the optical assembly has a 3 m diameter and a 2 m2 effective area at 1 keV, with a required angular resolution of 5 arcsec. The angular resolution that can be achieved is chiefly the combination of 1) the focal spot size determined by the pore diffraction, 2) the focus degradation caused by surface and profile errors, 3) the aberrations introduced by the misalignments between primary and secondary segments, 4) imperfections in the co-focality of the mirror modules in the optical assembly. A detailed simulation of these aspects is required in order to assess the fabrication and alignment tolerances; moreover, the achievable effective area and angular resolution depend on the mirror module design. Therefore, guaranteeing these optical performances requires: a fast design tool to find the most performing solution in terms of mirror module geometry and population, and an accurate point spread function simulation from local metrology and positioning information. In this paper, we present the results of simulations in the framework of ESA-financed projects (SIMPOSiuM, ASPHEA, SPIRIT), in preparation of the ATHENA X-ray telescope, analyzing the mentioned points: 1) we deal with a detailed description of diffractive effects in an SPO mirror module, 2) we show ray-tracing results including surface and profile defects of the reflective surfaces, 3) we assess the effective area and angular resolution degradation caused by alignment errors between SPO mirror module's segments, and 4) we simulate the effects of co-focality errors in X-rays and in the UV optical bench used to study the mirror module alignment and integration.

Field curvature correction method for ultrashort throw ratio projection optics design using an odd polynomial mirror surface.

PubMed

Zhuang, Zhenfeng; Chen, Yanting; Yu, Feihong; Sun, Xiaowei

2014-08-01

This paper presents a field curvature correction method of designing an ultrashort throw ratio (TR) projection lens for an imaging system. The projection lens is composed of several refractive optical elements and an odd polynomial mirror surface. A curved image is formed in a direction away from the odd polynomial mirror surface by the refractive optical elements from the image formed on the digital micromirror device (DMD) panel, and the curved image formed is its virtual image. Then the odd polynomial mirror surface enlarges the curved image and a plane image is formed on the screen. Based on the relationship between the chief ray from the exit pupil of each field of view (FOV) and the corresponding predescribed position on the screen, the initial profile of the freeform mirror surface is calculated by using segments of the hyperbolic according to the laws of reflection. For further optimization, the value of the high-order odd polynomial surface is used to express the freeform mirror surface through a least-squares fitting method. As an example, an ultrashort TR projection lens that realizes projection onto a large 50 in. screen at a distance of only 510 mm is presented. The optical performance for the designed projection lens is analyzed by ray tracing method. Results show that an ultrashort TR projection lens modulation transfer function of over 60% at 0.5 cycles/mm for all optimization fields is achievable with f-number of 2.0, 126° full FOV, <1% distortion, and 0.46 TR. Moreover, in comparing the proposed projection lens' optical specifications to that of traditional projection lenses, aspheric mirror projection lenses, and conventional short TR projection lenses, results indicate that this projection lens has the advantages of ultrashort TR, low f-number, wide full FOV, and small distortion.

Mirror Symmetric Bimanual Movement Priming Can Increase Corticomotor Excitability and Enhance Motor Learning

PubMed Central

Byblow, Winston D.; Stinear, Cathy M.; Smith, Marie-Claire; Bjerre, Lotte; Flaskager, Brian K.; McCambridge, Alana B.

2012-01-01

Repetitive mirror symmetric bilateral upper limb may be a suitable priming technique for upper limb rehabilitation after stroke. Here we demonstrate neurophysiological and behavioural after-effects in healthy participants after priming with 20 minutes of repetitive active-passive bimanual wrist flexion and extension in a mirror symmetric pattern with respect to the body midline (MIR) compared to an control priming condition with alternating flexion-extension (ALT). Transcranial magnetic stimulation (TMS) indicated that corticomotor excitability (CME) of the passive hemisphere remained elevated compared to baseline for at least 30 minutes after MIR but not ALT, evidenced by an increase in the size of motor evoked potentials in ECR and FCR. Short and long-latency intracortical inhibition (SICI, LICI), short afferent inhibition (SAI) and interhemispheric inhibition (IHI) were also examined using pairs of stimuli. LICI differed between patterns, with less LICI after MIR compared with ALT, and an effect of pattern on IHI, with reduced IHI in passive FCR 15 minutes after MIR compared with ALT and baseline. There was no effect of pattern on SAI or FCR H-reflex. Similarly, SICI remained unchanged after 20 minutes of MIR. We then had participants complete a timed manual dexterity motor learning task with the passive hand during, immediately after, and 24 hours after MIR or control priming. The rate of task completion was faster with MIR priming compared to control conditions. Finally, ECR and FCR MEPs were examined within a pre-movement facilitation paradigm of wrist extension before and after MIR. ECR, but not FCR, MEPs were consistently facilitated before and after MIR, demonstrating no degradation of selective muscle activation. In summary, mirror symmetric active-passive bimanual movement increases CME and can enhance motor learning without degradation of muscle selectivity. These findings rationalise the use of mirror symmetric bimanual movement as a priming modality in post-stroke upper limb rehabilitation. PMID:22457799

Tracing Success: Graphical Methods for Analysing Successful Collaborative Problem Solving

ERIC Educational Resources Information Center

Joiner, Richard; Issroff, Kim

2003-01-01

The aim of this paper is to evaluate the use of trace diagrams for analysing collaborative problem solving. The paper describes a study where trace diagrams were used to analyse joint navigation in a virtual environment. Ten pairs of undergraduates worked together on a distributed virtual task to collect five flowers using two bees with each…

Training-Dependent Associative Learning Induced Neocortical Structural Plasticity: A Trace Eyeblink Conditioning Analysis

PubMed Central

Chau, Lily S.; Prakapenka, Alesia V.; Zendeli, Liridon; Davis, Ashley S.; Galvez, Roberto

2014-01-01

Studies utilizing general learning and memory tasks have suggested the importance of neocortical structural plasticity for memory consolidation. However, these learning tasks typically result in learning of multiple different tasks over several days of training, making it difficult to determine the synaptic time course mediating each learning event. The current study used trace-eyeblink conditioning to determine the time course for neocortical spine modification during learning. With eyeblink conditioning, subjects are presented with a neutral, conditioned stimulus (CS) paired with a salient, unconditioned stimulus (US) to elicit an unconditioned response (UR). With multiple CS-US pairings, subjects learn to associate the CS with the US and exhibit a conditioned response (CR) when presented with the CS. Trace conditioning is when there is a stimulus free interval between the CS and the US. Utilizing trace-eyeblink conditioning with whisker stimulation as the CS (whisker-trace-eyeblink: WTEB), previous findings have shown that primary somatosensory (barrel) cortex is required for both acquisition and retention of the trace-association. Additionally, prior findings demonstrated that WTEB acquisition results in an expansion of the cytochrome oxidase whisker representation and synaptic modification in layer IV of barrel cortex. To further explore these findings and determine the time course for neocortical learning-induced spine modification, the present study utilized WTEB conditioning to examine Golgi-Cox stained neurons in layer IV of barrel cortex. Findings from this study demonstrated a training-dependent spine proliferation in layer IV of barrel cortex during trace associative learning. Furthermore, findings from this study showing that filopodia-like spines exhibited a similar pattern to the overall spine density further suggests that reorganization of synaptic contacts set the foundation for learning-induced neocortical modifications through the different neocortical layers. PMID:24760074

Development of low-stress Iridium coatings for astronomical x-ray mirrors

NASA Astrophysics Data System (ADS)

Döhring, Thorsten; Probst, Anne-Catherine; Stollenwerk, Manfred; Wen, Mingwu; Proserpio, Laura

2016-07-01

Previously used mirror technologies are not suitable for the challenging needs of future X-ray telescopes. This is why the required high precision mirror manufacturing triggers new technical developments around the world. Some aspects of X-ray mirrors production are studied within the interdisciplinary project INTRAAST, a German acronym for "industry transfer of astronomical mirror technologies". The project is embedded in a cooperation of Aschaffenburg University of Applied Sciences and the Max-Planck-Institute for extraterrestrial Physics. One important task is the development of low-stress Iridium coatings for X-ray mirrors based on slumped thin glass substrates. The surface figure of the glass substrates is measured before and after the coating process by optical methods. Correlating the surface shape deformation to the parameters of coating deposition, here especially to the Argon sputtering pressure, allows for an optimization of the process. The sputtering parameters also have an influence on the coating layer density and on the micro-roughness of the coatings, influencing their X-ray reflection properties. Unfortunately the optimum coating process parameters seem to be contrarious: low Argon pressure resulted in better micro-roughness and higher density, whereas higher pressure leads to lower coating stress. Therefore additional measures like intermediate coating layers and temperature treatment will be considered for further optimization. The technical approach for the low-stress Iridium coating development, the experimental equipment, and the obtained first experimental results are presented within this paper.

Nonword repetition priming in lexical decision reverses as a function of study task and speed stress.

PubMed

Zeelenberg, René; Wagenmakers, Eric-Jan; Shiffrin, Richard M

2004-01-01

The authors argue that nonword repetition priming in lexical decision is the net result of 2 opposing processes. First, repeating nonwords in the lexical decision task results in the storage of a memory trace containing the interpretation that the letter string is a nonword; retrieval of this trace leads to an increase in performance for repeated nonwords. Second, nonword repetition results in increased familiarity, making the nonword more "wordlike," leading to a decrease in performance. Consistent with this dual-process account, Experiment 1 showed a facilitatory effect for nonwords studied in a lexical decision task but an inhibitory effect for nonwords studied in a letter-height task. Experiment 2 showed inhibitory nonword repetition priming for participants tested under speed-stress instructions. ((c) 2004 APA, all rights reserved)

SXI Prototype mirror mount

NASA Technical Reports Server (NTRS)

1995-01-01

This final report describes the work performed from June 1993 to January 1995. The purpose of this contract was to provide optomechanical engineering and fabrication support to the Solar X-ray Imager (SXI) program in the areas of mirror, optical bench and camera assemblies of the telescope. The Center for Applied Optics (CAO) worked closely with the Optics and S&E technical staff of MSFC to develop and investigate the most viable and economical options for the design and fabrication of a number of parts for the various telescope assemblies. All the tasks under this delivery order have been successfully completed within budget and schedule.

Age-related differences in perceptuomotor procedural learning in children.

PubMed

Lejeune, Caroline; Catale, Corinne; Schmitz, Xavier; Quertemont, Etienne; Meulemans, Thierry

2013-10-01

Procedural learning is generally considered to proceed in a series of phases, with cognitive resources playing an important role during the initial step. From a developmental perspective, little is known about the development of procedural learning or the role played by explicit cognitive processes during learning. The main objectives of this study were (a) to determine whether procedural learning performance improves with age by comparing groups of 7-year-old children, 10-year-old children, and adults and (b) to investigate the role played by executive functions during the acquisition in these three age groups. The 76 participants were assessed on a computerized adaptation of the mirror tracing paradigm. Results revealed that the youngest children had more difficulty in adapting to the task (they were slower and committed more errors at the beginning of the learning process) than 10-year-olds, but despite this age effect observed at the outset, all children improved performance across trials and transferred their skill to a different figure as well as adults. Correlational analyses showed that inhibition abilities play a key role in the performance of 10-year-olds and adults at the beginning of the learning but not in that of 7-year-olds. Overall, our results suggest that the age-related differences observed in our procedural learning task are at least partly due to the differential involvement of inhibition abilities, which may facilitate learning (so long as they are sufficiently developed) during the initial steps of the learning process; however, they would not be a necessary condition for skill learning to occur. Copyright © 2013 Elsevier Inc. All rights reserved.

Lexical and semantic processing in the absence of word reading: evidence from neglect dyslexia.

PubMed

Làdavas, E; Umiltà, C; Mapelli, D

1997-08-01

Nine patients with left-sided neglect and nine matched control patients performed three tasks on horizontal (either normal or mirror-reversed) letter strings. The tasks were: reading aloud, making a lexical decision (word vs non-word), and making a semantic decision (living vs non-living item). Relative to controls, neglect patients performed very poorly in the reading task, whereas they performed nearly normally in the lexical and semantic tasks. This was considered to be a dissociation between direct tasks, rather than a dissociation between explicit and implicit knowledge. The explanation offered for the dissociation is in terms of both a dual-route model for reading aloud and a degraded representation of the letter string.

Software to model AXAF-I image quality

NASA Technical Reports Server (NTRS)

Ahmad, Anees; Feng, Chen

1995-01-01

A modular user-friendly computer program for the modeling of grazing-incidence type x-ray optical systems has been developed. This comprehensive computer software GRAZTRACE covers the manipulation of input data, ray tracing with reflectivity and surface deformation effects, convolution with x-ray source shape, and x-ray scattering. The program also includes the capabilities for image analysis, detector scan modeling, and graphical presentation of the results. A number of utilities have been developed to interface the predicted Advanced X-ray Astrophysics Facility-Imaging (AXAF-I) mirror structural and thermal distortions with the ray-trace. This software is written in FORTRAN 77 and runs on a SUN/SPARC station. An interactive command mode version and a batch mode version of the software have been developed.

Multilayer X-ray imaging systems

NASA Astrophysics Data System (ADS)

Shealy, D. L.; Hoover, R. B.; Gabardi, D. R.

1986-01-01

An assessment of the imaging properties of multilayer X-ray imaging systems with spherical surfaces has been made. A ray trace analysis was performed to investigate the effects of using spherical substrates (rather than the conventional paraboloidal/hyperboloidal contours) for doubly reflecting Cassegrain telescopes. These investigations were carried out for mirrors designed to operate at selected soft X-ray/XUV wavelengths that are of significance for studies of the solar corona/transition region from the Stanford/MSFC Rocket X-Ray Telescope. The effects of changes in separation of the primary and secondary elements were also investigated. These theoretical results are presented as well as the results of ray trace studies to establish the resolution and vignetting effects as a function of field angle and system parameters.

Brain regions with mirror properties: a meta-analysis of 125 human fMRI studies.

PubMed

Molenberghs, Pascal; Cunnington, Ross; Mattingley, Jason B

2012-01-01

Mirror neurons in macaque area F5 fire when an animal performs an action, such as a mouth or limb movement, and also when the animal passively observes an identical or similar action performed by another individual. Brain-imaging studies in humans conducted over the last 20 years have repeatedly attempted to reveal analogous brain regions with mirror properties in humans, with broad and often speculative claims about their functional significance across a range of cognitive domains, from language to social cognition. Despite such concerted efforts, the likely neural substrates of these mirror regions have remained controversial, and indeed the very existence of a distinct subcategory of human neurons with mirroring properties has been questioned. Here we used activation likelihood estimation (ALE), to provide a quantitative index of the consistency of patterns of fMRI activity measured in human studies of action observation and action execution. From an initial sample of more than 300 published works, data from 125 papers met our strict inclusion and exclusion criteria. The analysis revealed 14 separate clusters in which activation has been consistently attributed to brain regions with mirror properties, encompassing 9 different Brodmann areas. These clusters were located in areas purported to show mirroring properties in the macaque, such as the inferior parietal lobule, inferior frontal gyrus and the adjacent ventral premotor cortex, but surprisingly also in regions such as the primary visual cortex, cerebellum and parts of the limbic system. Our findings suggest a core network of human brain regions that possess mirror properties associated with action observation and execution, with additional areas recruited during tasks that engage non-motor functions, such as auditory, somatosensory and affective components. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Metal mirror TMA, telescopes of the JSS product line: design and analysis

NASA Astrophysics Data System (ADS)

Kirschstein, Steffen; Koch, Amelia; Schöneich, Jürgen; Döngi, Frank

2005-09-01

For the increasing market of low-cost multispectral pushbroom scanners for spaceborne Earth remote sensing the Jena-Optronik GmbH have developed the JSS product line. They are typically operated on micro-satellites with strong resources constraints. This leads to instrument designs optimised with respect to minimum size and mass, power consumption, and cost. From various customer requirements, Jena-Optronik has derived the JSS product line of low-cost optical spaceborne scanners in the visible wavelength range. Three-mirror anastigmat (TMA) telescope designs have become a widespread design solution for fields of view from 2 to 12 deg. The design solution chosen by Jena-Optronik is based on all-aluminium telescopes. Novel ultra-precision milling and polishing techniques now give the opportunity to achieve the necessary optical surface quality for applications in the visible range. The TMA telescope optics design of the JSS-56 imager will be accommodated onboard the RapidEye spacecraft. The JSS-56 TMA with a F-number of 4.3 realised a swath width of 78km with a Ground pixel resolution of 6.5m × 6.5m. The aluminium mirrors are Ni coated to achieve a suitable surface polish quality. This paper discusses typical requirements for the thermal design the bimetallic effects of the mirrors. To achieve a nearly diffracted limited imaging the typical surface irregularities due to the turning process have to be addressed in the ray tracing models. Analysis and integration of real mirror data in the ZEMAX design software are demonstrated here and compared with build-in standard tolerance concepts.

Static tool influence function for fabrication simulation of hexagonal mirror segments for extremely large telescopes.

PubMed

Kim, Dae Wook; Kim, Sug-Whan

2005-02-07

We present a novel simulation technique that offers efficient mass fabrication strategies for 2m class hexagonal mirror segments of extremely large telescopes. As the first of two studies in series, we establish the theoretical basis of the tool influence function (TIF) for precessing tool polishing simulation for non-rotating workpieces. These theoretical TIFs were then used to confirm the reproducibility of the material removal foot-prints (measured TIFs) of the bulged precessing tooling reported elsewhere. This is followed by the reverse-computation technique that traces, employing the simplex search method, the real polishing pressure from the empirical TIF. The technical details, together with the results and implications described here, provide the theoretical tool for material removal essential to the successful polishing simulation which will be reported in the second study.

Methods of Optimizing X-Ray Optical Prescriptions for Wide-Field Applications

NASA Technical Reports Server (NTRS)

Elsner, R. F.; O'Dell, S. L.; Ramsey, B. D.; Weisskopf, M. C.

2010-01-01

We are working on the development of a method for optimizing wide-field x-ray telescope mirror prescriptions, including polynomial coefficients, mirror shell relative displacements, and (assuming 4 focal plane detectors) detector placement and tilt that does not require a search through the multi-dimensional parameter space. Under the assumption that the parameters are small enough that second order expansions are valid, we show that the performance at the detector surface can be expressed as a quadratic function of the parameters with numerical coefficients derived from a ray trace through the underlying Wolter I optic. The best values for the parameters are found by solving the linear system of equations creating by setting derivatives of this function with respect to each parameter to zero. We describe the present status of this development effort.

Optical design of free face reflective headlamps

NASA Astrophysics Data System (ADS)

Cen, Zhao Feng; Li, Xiao Tong; Deng, Shi Tao

2005-02-01

Headlamps are installed at the head of automobiles for road lighting. About the illumination and anti-dazzle, some standards such as the standard of ECE are established. Now more and more free face reflective headlamps (FFR headlamps) are applied, and the light distribution design of FFR mirror becomes an important subject in the field of automobile assembling part. In this paper the surface shape of FFR headlamps is analyzed and described as a multi-partition aspherical surface with some simple parameters. According to the fundamental principles of geometrical optics and using the theory of ray transmission with energy, millions of real rays emitted from lower beam filament and high beam filament are traced and the relative intensity of illumination at the test screen with distance of 25m from the automobiles is obtained. In this paper the description of FFR mirrors is discussed, the algorithm of FFR headlamp design is presented, the flow chart is given and the light distribution simulation software with friendly interfaces is developed. In the light distribution graphic interface of the software, the illumination area could be dragged to a certain position while the parameters of current partition at the FFR mirror will be automatically changed. Using this software the FFR headlamps satisfying criteria will be designed very quickly and the 3D coordinates of any points at the mirror will be obtained. This makes CAM of FFR headlamps easy.

Aberration analysis of the putative projector for Lorenzo Lotto's Husband and wife: image analysis through computer ray-tracing

NASA Astrophysics Data System (ADS)

Robinson, Dirk; Stork, David G.

2008-02-01

A recent theory claims that the late-Italian Renaissance painter Lorenzo Lotto secretly built a concave-mirror projector to project an image of a carpet onto his canvas and trace it during the execution of Husband and wife (c. 1543). Key evidence adduced to support this claim includes "perspective anomalies" and changes in "magnification" that the theory's proponents ascribe to Lotto refocusing his projector to overcome its limitations in depth of field. We find, though, that there are important geometrical constraints upon such a putative optical projector not incorporated into the proponents' analyses, and that when properly included, the argument for the use of optics loses its force. We used Zemax optical design software to create a simple model of Lotto's studio and putative projector, and incorporated the optical properties proponents inferred from geometrical properties of the depicted carpet. Our central contribution derives from including the 116-cm-wide canvas screen; we found that this screen forces the incident light to strike the concave mirror at large angles (>= 15°) and that this, in turn, means that the projected image would reveal severe off-axis aberrations, particularly astigmatism. Such aberrations are roughly as severe as the defocus blur claimed to have led Lotto to refocus the projector. In short, we find that the projected images would not have gone in and out of focus in the way claimed by proponents, a result that undercuts their claim that Lotto used a projector for this painting. We speculate on the value of further uses of sophisticated ray-tracing analyses in the study of fine arts.

Development of replicated optics for AXAF-1 XDA testing

NASA Technical Reports Server (NTRS)

Engelhaupt, Darell; Wilson, Michele; Martin, Greg

1995-01-01

Advanced optical systems for applications such as grazing incidence Wolter I x-ray mirror assemblies require extraordinary mirror surfaces in terms of fine finish and surface figure. The impeccable mirror surface is on the inside of the rotational mirror form. One practical method of producing devices with these requirements is to first fabricate an exterior surface for the optical device then replicate that surface to have the inverse component with lightweight characteristics. The replicated optic is not better than the master or mandrel from which it is made. This task identifies methods and materials for forming these extremely low roughness optical components. The objectives of this contract were to (1) prepare replication samples of electroless nickel coated aluminum, and determine process requirements for plating XDA test optic; (2) prepare and assemble plating equipment required to process a demonstration optic; (3) characterize mandrels, replicas and test samples for residual stress, surface contamination and surface roughness and figure using equipment at MSFC and; (4) provide technical expertise in establishing the processes, procedures, supplies and equipment needed to process the XDA test optics.

Structured light stereo catadioptric scanner based on a spherical mirror

NASA Astrophysics Data System (ADS)

Barone, S.; Neri, P.; Paoli, A.; Razionale, A. V.

2018-08-01

The present paper describes the development and characterization of a structured light stereo catadioptric scanner for the omnidirectional reconstruction of internal surfaces. The proposed approach integrates two digital cameras, a multimedia projector and a spherical mirror, which is used to project the structured light patterns generated by the light emitter and, at the same time, to reflect into the cameras the modulated fringe patterns diffused from the target surface. The adopted optical setup defines a non-central catadioptric system, thus relaxing any geometrical constraint in the relative placement between optical devices. An analytical solution for the reflection on a spherical surface is proposed with the aim at modelling forward and backward projection tasks for a non-central catadioptric setup. The feasibility of the proposed active catadioptric scanner has been verified by reconstructing various target surfaces. Results demonstrated a great influence of the target surface distance from the mirror's centre on the measurement accuracy. The adopted optical configuration allows the definition of a metrological 3D scanner for surfaces disposed within 120 mm from the mirror centre.

The effect of self-focused attention and mood on appearance dissatisfaction after mirror-gazing: An experimental study.

PubMed

Veale, David; Miles, Sarah; Valiallah, Natasha; Butt, Saira; Anson, Martin; Eshkevari, Ertimiss; Gledhill, Lucinda J; Baldock, Emma

2016-09-01

Self-focused attention is hypothesized to be a maintenance factor in body dysmorphic disorder (BDD). The aim of this study was to use an experimental paradigm to test this hypothesis by studying the effect of self-focused attention during mirror-gazing on appearance dissatisfaction. An experimental group design was used, in which 173 women were randomly allocated to one of three conditions before mirror-gazing for 2 min: (a) external focus of attention, (b) self-focus of attention, and (c) self-focus of attention with a negative mood induction. After mirror-gazing, participants across all groups rated themselves as being more dissatisfied with their appearance. In both the self-focus conditions, there was an increase in sadness from pre to post mirror gazing, and there was a significant difference in focus of attention for participants in the self-focused, mood-induced group from pre to post manipulation, suggesting mood induction had more of an effect than focus of attention. (1) there was no condition involving an external focus with a negative mood induction, and (2) due to the level of information provided to patients on the nature of the task, we cannot rule out demand characteristics as an influencing factor on our results. Self-focused attention during mirror-gazing may act indirectly to increase appearance dissatisfaction via the effect of negative mood. Further studies are required to establish the relative contribution of self-focused attention and negative mood to increases in appearance dissatisfaction as a function of mirror-gazing. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Mirror Illusion Increases Motor Cortex Excitability in Children With and Without Hemiparesis.

PubMed

Grunt, Sebastian; Newman, Christopher J; Saxer, Stefanie; Steinlin, Maja; Weisstanner, Christian; Kaelin-Lang, Alain

2017-03-01

Mirror therapy provides a visual illusion of a normal moving limb by using the mirror reflection of the unaffected arm instead of viewing the paretic limb and is used in rehabilitation to improve hand function. Little is known about the mechanism underlying its effect in children with hemiparesis. To investigate the effect of the mirror illusion (MI) on the excitability of the primary motor cortex (M1) in children and adolescents. Twelve patients with hemiparesis (10-20 years) and 8 typically developing subjects (8-17 years) participated. Corticospinal reorganization was classified as contralateral (projection from contralateral hemisphere to affected hand) or ipsilateral (projection from ipsilateral hemisphere to affected hand). M1 excitability of the hemisphere projecting to the affected (nondominant in typically developing subjects) hand was obtained during 2 different conditions using single-pulse transcranial magnetic stimulation (TMS). Each condition (without/with mirror) consisted of a unimanual and a bimanual task. Motor-evoked potentials (MEPs) were recorded from the abductor pollicis brevis and flexor digitorum superficialis muscles. MEP amplitudes were significantly increased during the mirror condition ( P = .005) in typically developing subjects and in patients with contralateral reorganization. No significant effect of MI was found in subjects with ipsilateral reorganization. MI increased M1 excitability during active movements only. This increase was not correlated to hand function. MI increases the excitability of M1 in hemiparetic patients with contralateral corticospinal organization and in typically developing subjects. This finding provides neurophysiological evidence supporting the application of mirror therapy in selected children and adolescents with hemiparesis.

Mirror therapy for phantom limb pain: brain changes and the role of body representation.

PubMed

Foell, J; Bekrater-Bodmann, R; Diers, M; Flor, H

2014-05-01

Phantom limb pain (PLP) is a common consequence of amputation and is difficult to treat. Mirror therapy (MT), a procedure utilizing the visual recreation of movement of a lost limb by moving the intact limb in front of a mirror, has been shown to be effective in reducing PLP. However, the neural correlates of this effect are not known. We investigated the effects of daily mirror training over 4 weeks in 13 chronic PLP patients after unilateral arm amputation. Eleven participants performed hand and lip movements during a functional magnetic resonance imaging (fMRI) measurement before and after MT. The location of neural activity in primary somatosensory cortex during these tasks was used to assess brain changes related to treatment. The treatment caused a significant reduction of PLP (average decrease of 27%). Treatment effects were predicted by a telescopic distortion of the phantom, with those patients who experienced a telescope profiting less from treatment. fMRI data analyses revealed a relationship between change in pain after MT and a reversal of dysfunctional cortical reorganization in primary somatosensory cortex. Pain reduction after mirror training was also related to a decrease of activity in the inferior parietal cortex (IPC). Experienced body appearance seems to be an important predictor of mirror treatment effectiveness. Maladaptive changes in cortical organization are reversed during mirror treatment, which also alters activity in the IPC, a region involved in painful perceptions and in the perceived relatedness to an observed limb. © 2013 The Authors. European Journal of Pain published by John Wiley & Sons Ltd on behalf of European Pain Federation - EFIC®.

Fabrication of the Advanced X-ray Astrophysics Facility (AXAF) Optics: A Deterministic, Precision Engineering Approach to Optical Fabrication

NASA Technical Reports Server (NTRS)

Gordon, T. E.

1995-01-01

The mirror assembly of the AXAF observatory consists of four concentric, confocal, Wolter type 1 telescopes. Each telescope includes two conical grazing incidence mirrors, a paraboloid followed by a hyperboloid. Fabrication of these state-or-the-art optics is now complete, with predicted performance that surpasses the goals of the program. The fabrication of these optics, whose size and requirements exceed those of any previous x-ray mirrors, presented a challenging task requiring the use of precision engineering in many different forms. Virtually all of the equipment used for this effort required precision engineering. Accurate metrology required deterministic support of the mirrors in order to model the gravity distortions which will not be present on orbit. The primary axial instrument, known as the Precision Metrology Station (PMS), was a unique scanning Fizeau interferometer. After metrology was complete, the optics were placed in specially designed Glass Support Fixtures (GSF's) for installation on the Automated Cylindrical Grinder/Polishers (ACG/P's). The GSF's were custom molded for each mirror element to match the shape of the outer surface to minimize distortions of the inner surface. The final performance of the telescope is expected to far exceed the original goals and expectations of the program.

Boosting the Motor Outcome of the Untrained Hand by Action Observation: Mirror Visual Feedback, Video Therapy, or Both Combined-What Is More Effective?

PubMed

Bähr, Florian; Ritter, Alexander; Seidel, Gundula; Puta, Christian; Gabriel, Holger H W; Hamzei, Farsin

2018-01-01

Action observation (AO) allows access to a network that processes visuomotor and sensorimotor inputs and is believed to be involved in observational learning of motor skills. We conducted three consecutive experiments to examine the boosting effect of AO on the motor outcome of the untrained hand by either mirror visual feedback (MVF), video therapy (VT), or a combination of both. In the first experiment, healthy participants trained either with MVF or without mirror feedback while in the second experiment, participants either trained with VT or observed animal videos. In the third experiment, participants first observed video clips that were followed by either training with MVF or training without mirror feedback. The outcomes for the untrained hand were quantified by scores from five motor tasks. The results demonstrated that MVF and VT significantly increase the motor performance of the untrained hand by the use of AO. We found that MVF was the most effective approach to increase the performance of the target effector. On the contrary, the combination of MVF and VT turns out to be less effective looking from clinical perspective. The gathered results suggest that action-related motor competence with the untrained hand is acquired by both mirror-based and video-based AO.

Boosting the Motor Outcome of the Untrained Hand by Action Observation: Mirror Visual Feedback, Video Therapy, or Both Combined—What Is More Effective?

PubMed Central

Ritter, Alexander; Seidel, Gundula; Puta, Christian; Gabriel, Holger H. W.; Hamzei, Farsin

2018-01-01

Action observation (AO) allows access to a network that processes visuomotor and sensorimotor inputs and is believed to be involved in observational learning of motor skills. We conducted three consecutive experiments to examine the boosting effect of AO on the motor outcome of the untrained hand by either mirror visual feedback (MVF), video therapy (VT), or a combination of both. In the first experiment, healthy participants trained either with MVF or without mirror feedback while in the second experiment, participants either trained with VT or observed animal videos. In the third experiment, participants first observed video clips that were followed by either training with MVF or training without mirror feedback. The outcomes for the untrained hand were quantified by scores from five motor tasks. The results demonstrated that MVF and VT significantly increase the motor performance of the untrained hand by the use of AO. We found that MVF was the most effective approach to increase the performance of the target effector. On the contrary, the combination of MVF and VT turns out to be less effective looking from clinical perspective. The gathered results suggest that action-related motor competence with the untrained hand is acquired by both mirror-based and video-based AO. PMID:29849570

Goals, intentions and mental states: challenges for theories of autism.

PubMed

Hamilton, Antonia F de C

2009-08-01

The ability to understand the goals and intentions behind other people's actions is central to many social interactions. Given the profound social difficulties seen in autism, we might expect goal understanding to be impaired in these individuals. Two influential theories, the 'broken mirror' theory and the mentalising theory, can both predict this result. However, a review of the current data provides little empirical support for goal understanding difficulties; several studies demonstrate normal performance by autistic children on tasks requiring the understanding of goals or intentions. I suggest that this conclusion forces us to reject the basic broken mirror theory and to re-evaluate the breadth of the mentalising theory. More subtle theories which distinguish between different types of mirroring and different types of mentalising may be able to account for the present data, and further research is required to test and refine these theories.

A Motion Capture Study to Measure the Feeling of Synchrony in Romantic Couples and in Professional Musicians

PubMed Central

Preissmann, Delphine; Charbonnier, Caecilia; Chagué, Sylvain; Antonietti, Jean-Philippe; Llobera, Joan; Ansermet, Francois; Magistretti, Pierre J.

2016-01-01

The feeling of synchrony is fundamental for most social activities and prosocial behaviors. However, little is known about the behavioral correlates of this feeling and its modulation by intergroup differences. We previously showed that the subjective feeling of synchrony in subjects involved in a mirror imitation task was modulated by objective behavioral measures, as well as contextual factors such as task difficulty and duration of the task performance. In the present study, we extended our methodology to investigate possible interindividual differences. We hypothesized that being in a romantic relationship or being a professional musician can modulate both implicit and explicit synchronization and the feeling of synchrony as well as the ability to detect synchrony from a third person perspective. Contrary to our hypothesis, we did not find significant differences between people in a romantic relationship and control subjects. However, we observed differences between musicians and control subjects. For the implicit synchrony (spontaneous synchronization during walking), the results revealed that musicians that had never met before spontaneously synchronized their movements earlier among themselves than control subjects, but not better than people sharing a romantic relationship. Moreover, in explicit behavioral synchronization tasks (mirror game), musicians reported earlier feeling of synchrony and had less speed errors than control subjects. This was in interaction with tasks difficulty as these differences appeared only in tasks with intermediate difficulty. Finally, when subjects had to judge synchrony from a third person perspective, musicians had a better performance to identify if they were present or not in the videos. Taken together, our results suggest that being a professional musician can play a role in the feeling of synchrony and its underlying mechanisms. PMID:27833580

Feasibility and effectiveness of adding object-related bilateral symmetrical training to mirror therapy in chronic stroke: A randomized controlled pilot study.

PubMed

Rodrigues, Letícia Cardoso; Farias, Nayara Correa; Gomes, Raquel Pinheiro; Michaelsen, Stella Maris

2016-01-01

To evaluate the feasibility and effectiveness of adding object-related bilateral symmetrical training to mirror therapy (MT) to improve upper limb (UL) activity in chronic stroke patients. Sixteen patients with moderate UL impairment were randomly allocated to either the experimental (EG) or control (CG) group. Both groups performed 1 hour sessions, 3 days/week for 4 weeks, involving object-related bilateral symmetrical training. EG performed the tasks observing their nonparetic UL reflected in the mirror, while CG observed the paretic UL directly. The primary outcome measure was unilateral and bilateral UL activity according to the Test d'Évaluation des Membres Supérieurs de Personnes Âgées (TEMPA). All measurements were taken at baseline, post-training, and follow-up (2 weeks). TEMPA total score showed the main effect of time. Significant improvement was found for bilateral but not unilateral tasks. Both groups showed gains after training, with no differences between them. This study showed the feasibility of adding object-related bilateral training to MT. Both types of training improved UL bilateral activity; however, a larger sample is required for a definitive study. Other studies need to be carried out to evaluate the effectiveness of combining more distal-oriented movements and object-related unilateral training to improve these effects in chronic stroke patients.

The influence of AVPR1A genotype on individual differences in behaviors during a mirror self-recognition task in chimpanzees (Pan troglodytes).

PubMed

Mahovetz, L M; Young, L J; Hopkins, W D

2016-06-01

The mark/rouge test has been used to assess mirror self-recognition (MSR) in many species. Despite consistent evidence of MSR in great apes, genetic or non-genetic factors may account for the individual differences in behavioral responses that have been reported. We examined whether vasopressin receptor gene (AVPR1A) polymorphisms are associated with MSR-related behaviors in chimpanzees since vasopressin has been implicated in the development and evolution of complex social relations and cognition and chimpanzees are polymorphic for the presence of the RS3-containing DupB region. We compared a sample of DupB+/- and DupB-/- chimpanzees on a mark test to assess its role on social behavior toward a mirror. Chimpanzees were administered two, 10-min sessions where frequencies of mirror-guided self-directed behaviors, contingent actions and other social behaviors were recorded. Approximately one-third showed evidence of MSR and these individuals exhibited more mirror-guided self-exploratory behaviors and mouth contingent actions than chimpanzees not classified as passers. Moreover, DupB+/- males exhibited more scratching and agonistic behaviors than other male and female cohorts. Our findings support previous studies demonstrating individual differences in MSR abilities in chimpanzees and suggest that AVPR1A partly explains individual differences in MSR by influencing the behavioral reactions of chimpanzees in front of a mirror. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

Complementary Hand Responses Occur in Both Peri- and Extrapersonal Space.

PubMed

Faber, Tim W; van Elk, Michiel; Jonas, Kai J

2016-01-01

Human beings have a strong tendency to imitate. Evidence from motor priming paradigms suggests that people automatically tend to imitate observed actions such as hand gestures by performing mirror-congruent movements (e.g., lifting one's right finger upon observing a left finger movement; from a mirror perspective). Many observed actions however, do not require mirror-congruent responses but afford complementary (fitting) responses instead (e.g., handing over a cup; shaking hands). Crucially, whereas mirror-congruent responses don't require physical interaction with another person, complementary actions often do. Given that most experiments studying motor priming have used stimuli devoid of contextual information, this space or interaction-dependency of complementary responses has not yet been assessed. To address this issue, we let participants perform a task in which they had to mirror or complement a hand gesture (fist or open hand) performed by an actor depicted either within or outside of reach. In three studies, we observed faster reaction times and less response errors for complementary relative to mirrored hand movements in response to open hand gestures (i.e., 'hand-shaking') irrespective of the perceived interpersonal distance of the actor. This complementary effect could not be accounted for by a low-level spatial cueing effect. These results demonstrate that humans have a strong and automatic tendency to respond by performing complementary actions. In addition, our findings underline the limitations of manipulations of space in modulating effects of motor priming and the perception of affordances.

Mirror Neuron System and Mentalizing System connect during online social interaction.

PubMed

Sperduti, Marco; Guionnet, Sophie; Fossati, Philippe; Nadel, Jacqueline

2014-08-01

Two sets of brain areas are repeatedly reported in neuroimaging studies on social cognition: the Mirror Neuron System and the Mentalizing System. The Mirror System is involved in goal understanding and has been associated with several emotional and cognitive functions central to social interaction, ranging from empathy to gestural communication and imitation. The Mentalizing System is recruited in tasks requiring cognitive processes such as self-reference and understanding of other's intentions. Although theoretical accounts for an interaction between the two systems have been proposed, little is known about their synergy during social exchanges. In order to explore this question, we have recorded brain activity by means of functional MRI during live social exchanges based on reciprocal imitation of hand gestures. Here, we investigate, using the method of psychophysiological interaction, the changes in functional connectivity of the Mirror System due to the conditions of interest (being imitated, imitating) compared with passive observation of hand gestures. We report a strong coupling between the Mirror System and the Mentalizing System during the imitative exchanges. Our findings suggest a complementary role of the two networks during social encounters. The Mirror System would engage in the preparation of own actions and the simulation of other's actions, while the Mentalizing System would engage in the anticipation of the other's intention and thus would participate to the co-regulation of reciprocal actions. Beyond a specific effect of imitation, the design used offers the opportunity to tackle the role of role-switching in an interpersonal account of social cognition.

Rules for Optical Testing

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2014-01-01

Based on 30 years of optical testing experience, a lot of mistakes, a lot of learning and a lot of experience, I have defined seven guiding principles for optical testing - regardless of how small or how large the optical testing or metrology task: Fully Understand the Task, Develop an Error Budget, Continuous Metrology Coverage, Know where you are, Test like you fly, Independent Cross-Checks, Understand All Anomalies. These rules have been applied with great success to the inprocess optical testing and final specification compliance testing of the JWST mirrors.

Gamma bang time/reaction history diagnostics for the National Ignition Facility using 90 degrees off-axis parabolic mirrors.

PubMed

Malone, R M; Herrmann, H W; Stoeffl, W; Mack, J M; Young, C S

2008-10-01

Gas Cherenkov detectors (GCDs) have been used to convert fusion gamma into photons to achieve gamma bang time and reaction history measurements. The GCDs designed for OMEGA used Cassegrain reflector optics in order to fit inside a 10 in. manipulator. A novel design for the National Ignition Facility using 90 degrees off-axis parabolic mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO(2) gas volume, the detector is positioned at the stop position rather than at an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100 mm diameter by 500 mm long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO(2) gas volume. A cluster of four channels will allow for increased dynamic range as well as for different gamma energy threshold sensitivities.

Tracing a Route and Finding a Shortcut: The Working Memory, Motivational, and Personality Factors Involved.

PubMed

Pazzaglia, Francesca; Meneghetti, Chiara; Ronconi, Lucia

2018-01-01

Wayfinding (WF) is the ability to move around efficiently and find the way from a starting point to a destination. It is a component of spatial navigation, a coordinate and goal-directed movement of one's self through the environment. In the present study, the relationship between WF tasks (route tracing and shortcut finding) and individual factors were explored with the hypothesis that WF tasks would be predicted by different types of cognitive, affective, motivational variables, and personality factors. A group of 116 university students (88 F.) were conducted along a route in a virtual environment and then asked first to trace the same route again, and then to find a shortcut between the start and end points. Several instruments assessing visuospatial working memory, mental rotation ability, self-efficacy, spatial anxiety, positive attitude to exploring, and personality traits were administered. The results showed that a latent spatial ability factor (measured with the visuospatial working memory and mental rotations tests) - controlled for gender - predicted route-tracing performance, while self-report measures of anxiety, efficacy, and pleasure in exploring, and some personality traits were more likely to predict shortcut-finding performance. We concluded that both personality and cognitive abilities affect WF performance, but differently, depending on the requirements of the task.

Focal dystonia of right hand with mirror movements upon use of left arm.

PubMed

Rana, Abdul Qayyum; Athar, Aysha

2013-05-01

Dystonia is a movement disorder characterized by sustained muscle contractions, causing twisting and repetitive movements or abnormal postures of affected body parts. Here, we present a novel case of focal dystonia of a 51 years old right-handed woman who had developed difficulty in writing and performing fine motor tasks. Due to a discomfort in her right hand at use, she started using her left hand instead and noticed inconsistent mirror movements in her right hand upon use of left hand. She was treated with trihexyphenidyl which allowed her right hand to function better, though writing still remained a problem.

Improved methods for dewarping images in convex mirrors in fine art: applications to van Eyck and Parmigianino

NASA Astrophysics Data System (ADS)

Usami, Yumi; Stork, David G.; Fujiki, Jun; Hino, Hideitsu; Akaho, Shotaro; Murata, Noboru

2011-03-01

We derive and demonstrate new methods for dewarping images depicted in convex mirrors in artwork and for estimating the three-dimensional shapes of the mirrors themselves. Previous methods were based on the assumption that mirrors were spherical or paraboloidal, an assumption unlikely to hold for hand-blown glass spheres used in early Renaissance art, such as Johannes van Eyck's Portrait of Giovanni (?) Arnolfini and his wife (1434) and Robert Campin's Portrait of St. John the Baptist and Heinrich von Werl (1438). Our methods are more general than such previous methods in that we assume merely that the mirror is radially symmetric and that there are straight lines (or colinear points) in the actual source scene. We express the mirror's shape as a mathematical series and pose the image dewarping task as that of estimating the coefficients in the series expansion. Central to our method is the plumbline principle: that the optimal coefficients are those that dewarp the mirror image so as to straighten lines that correspond to straight lines in the source scene. We solve for these coefficients algebraically through principal component analysis, PCA. Our method relies on a global figure of merit to balance warping errors throughout the image and it thereby reduces a reliance on the somewhat subjective criterion used in earlier methods. Our estimation can be applied to separate image annuli, which is appropriate if the mirror shape is irregular. Once we have found the optimal image dewarping, we compute the mirror shape by solving a differential equation based on the estimated dewarping function. We demonstrate our methods on the Arnolfini mirror and reveal a dewarped image superior to those found in prior work|an image noticeably more rectilinear throughout and having a more coherent geometrical perspective and vanishing points. Moreover, we find the mirror deviated from spherical and paraboloidal shape; this implies that it would have been useless as a concave projection mirror, as has been claimed. Our dewarped image can be compared to the geometry in the full Arnolfini painting; the geometrical agreement strongly suggests that van Eyck worked from an actual room, not, as has been suggested by some art historians, a "fictive" room of his imagination. We apply our method to other mirrors depicted in art, such as Parmigianino's Self-portrait in a convex mirror and compare our results to those from earlier computer graphics simulations.

The role of large and small cometary showers in the changes of living conditions on the Earth

NASA Astrophysics Data System (ADS)

Churyumov, K. I.; Steklov, A. F.; Vidmachenko, A. P.; Dashkiev, G. N.; Stepahno, I. V.; Steklov, E. A.; Slipchenko, A. S.; Romaniuk, Ya. O.

2016-10-01

1. The supremum of astrophysical problems in modern astronomy. With the introduction into service in 1974, of the largest at that time, six-meter telescope BTA at Zelenchukskaya Astrophysical Observatory (SAO) - Department of Extragalactic Research and relativistic astrophysics was established. Its main task was to study the so-called super-distant boundary fields and extreme states of substances of stars, galactic nuclei in the early epoch of the Universe. Now, after 40 years, these tasks are as popular and relevant: quasars, pulsars, gravitational lenses, black holes, active galactic nuclei, etc. Already established telescopes with diameters of multicomponent mirrors of 8-10 meters or more. Astronomical observatories had gone high into the mountains, to the special mountain on the islands in the oceans, in the alpine desert and into space. Extreme problems on the supremum still attracts the strongest efforts of astrophysicists in the world. But what about the other side of extreme tasks: with the tasks of astrophysics for "infimum"? Let us consider the astrophysical problems of "infimum" in more detail. 2. Infinum of astrophysical problems in modern astronomy. We believe that among the tasks of modern astrophysics can be super-close latent invasion (SCLI). If SCLI develop the concepts of cosmology, our views on the entire universe, on special times and special state of substance, then the infimum problem solving and must save the people and all living creatures on the planet against various types of aerospace dangerous intruders. SСLІ tasks are vital for all of us. These problems must be solved by leaders of countries and of concrete cities. The essence of these tasks determined the real threats and real fears against quite possibly over-close encounters with deadly consequences for all mankind intrusion of comets nucleus and asteroids, as well as the hidden, latent threat against far more numerous invasions of fragments of these bodies. And it is a completely different parties of the well-known asteroid-comet hazard and, especially, of large and small cometary showers. 3. Structural elements "Churyumov Unified Network". Summarize our proposals on the organization of effective structures "Churyumov Unified Network" [1-3, 5, 7-12] for terrestrial Aerospace Monitoring Services (TAMS) traces of all kinds of dangerous intrusions into the skies over our cities and countries. Recall that astrophysicists are most interested traces of dangerous intrusion of fragments of comets and asteroids, meteoroids, fireballs destroying (DIFCAMFD). As a result, we have: 3.1. Churyumov Conceptual club. We create, organize creative associations, collectives of Wildlife Photography on traces of intrusion; we make out it as a Churyumov Conceptual club, groups of simply connected Wildlife Photography on daytime and twilight traces of all kinds of dangerous intrusion. In our "Churyumov Unified Network" this structure is successfully operating since March 2013 [10]. Special registration invasion of the area of the Brovary city near Kiev was made by assistant professor Stepahno IV in December 1998. This organization has given us more than 36000 pictures in our data base. 3.2. Basic services of SAO TAMS. In our works we have described the purpose and meaning of the creation of stationary astronomical observatory (of SAO) of terrestrial aerospace monitoring services. Modern technical design of facilities in observations should "lift" mathematical horizon above the true horizon at the installation site of the photographic automated unified (PGAU). 3.3. Special TAMS MAO services. Each of SAO TAMS services necessary to deploy 1-3 mobile astronomical observatories (MAO) TAMS services. These specialized vehicles at astronomical observatories significantly strengthen the chances of success at "catching" and photodetection of traces of dangerous intrusion in conditions of positional observations. We note the success and the fact of use on Dnieper River near Kyiv of specialized yachts with photorecorder, implemented by assistant professor G.N. Dashkiev. That's why we build big plans in this direction with the creation of several specialized yachts, which can be used in Kiev, Odessa, Nikolaev, where there is an astronomical observatory and meteor patrols. A large comet showers have to capture still far enough in space because they are deadly to of life on Earth. 3.4. Special AAO TAMS our services. Traditional Astronomical observatories (AO Kiev University. Shevchenko, MAO NASU, etc.) in need of of specialized aerial astronomical observatories (AAO) TAMS services based on of use drones, quadrocopters, unmanned aerial vehicles (UAVs) with reliable PGAU [ 4, 6]. This is another important area for scientific and technical development services in TAMS "Churyumov Unified Network". 4. The International Academic Senate (IAS) and its role in the coordination of terrestrial services and networks, mobile, airborne and orbital space monitoring. Chief Scientific Secretary of the IAS Dashkiev GN not just passionate about photo-shoot on all kinds of dangerous intrusion into the sky over our cities, as has already been a great experience and significant progress in our common cause. Therefore, we hope not only to support the leadership of Ukraine, National Academy of Sciences, Security Service of Ukraine, the Emergencies Ministry, but also in the constructive and mutually beneficial cooperation with other countries

Design of the soft x-ray tomography beamline at Taiwan photon source

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

Su, Yi-Jr, E-mail: su.yj@nsrrc.org.tw; Fu, Huang-Wen; Chung, Shih-Chun

2016-07-27

The optical design of the varied-line-spacing plane-grating monochromator for transmission full-field imaging of frozen-hydrated biological samples at NSRRC is presented. This monochromator consists of a plane mirror and three interchangeable gratings with groove densities 600, 1200 and 2400 l/mm to cover the energy range 260 – 2600 eV. The groove parameters of the varied-line-spacing plane gratings are designed to minimize the effect of coma and spherical aberration to maintain the exit slit in focus for any value of incident angle. All parameters of optical components at the beamline are verified with a ray-tracing method. In the beamline design, the calculatedmore » results from the ray-tracing codes and the expected performances are discussed.« less

Optimization and performance evaluation of a conical mirror based fluorescence molecular tomography imaging system

NASA Astrophysics Data System (ADS)

Zhao, Yue; Zhang, Wei; Zhu, Dianwen; Li, Changqing

2016-03-01

We performed numerical simulations and phantom experiments with a conical mirror based fluorescence molecular tomography (FMT) imaging system to optimize its performance. With phantom experiments, we have compared three measurement modes in FMT: the whole surface measurement mode, the transmission mode, and the reflection mode. Our results indicated that the whole surface measurement mode performed the best. Then, we applied two different neutral density (ND) filters to improve the measurement's dynamic range. The benefits from ND filters are not as much as predicted. Finally, with numerical simulations, we have compared two laser excitation patterns: line and point. With the same excitation position number, we found that the line laser excitation had slightly better FMT reconstruction results than the point laser excitation. In the future, we will implement Monte Carlo ray tracing simulations to calculate multiple reflection photons, and create a look-up table accordingly for calibration.

X-ray metrology and performance of a 45-cm long x-ray deformable mirror

DOE PAGES

Poyneer, Lisa A.; Brejnholt, Nicolai F.; Hill, Randall; ...

2016-05-20

We describe experiments with a 45-cm long x-ray deformable mirror (XDM) that have been conducted in End Station 2, Beamline 5.3.1 at the Advanced Light Source. A detailed description of the hardware implementation is provided. We explain our one-dimensional Fresnel propagation code that correctly handles grazing incidence and includes a model of the XDM. This code is used to simulate and verify experimental results. Initial long trace profiler metrology of the XDM at 7.5 keV is presented. The ability to measure a large (150-nm amplitude) height change on the XDM is demonstrated. The results agree well with the simulated experimentmore » at an error level of 1 μrad RMS. Lastly, direct imaging of the x-ray beam also shows the expected change in intensity profile at the detector.« less

X-ray metrology and performance of a 45-cm long x-ray deformable mirror

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

Poyneer, Lisa A., E-mail: poyneer1@llnl.gov; Brejnholt, Nicolai F.; Hill, Randall

2016-05-15

We describe experiments with a 45-cm long x-ray deformable mirror (XDM) that have been conducted in End Station 2, Beamline 5.3.1 at the Advanced Light Source. A detailed description of the hardware implementation is provided. We explain our one-dimensional Fresnel propagation code that correctly handles grazing incidence and includes a model of the XDM. This code is used to simulate and verify experimental results. Initial long trace profiler metrology of the XDM at 7.5 keV is presented. The ability to measure a large (150-nm amplitude) height change on the XDM is demonstrated. The results agree well with the simulated experimentmore » at an error level of 1 μrad RMS. Direct imaging of the x-ray beam also shows the expected change in intensity profile at the detector.« less

Language Helps Children Succeed on a Classic Analogy Task

ERIC Educational Resources Information Center

Christie, Stella; Gentner, Dedre

2014-01-01

Adult humans show exceptional relational ability relative to other species. In this research, we trace the development of this ability in young children. We used a task widely used in comparative research--the relational match-to-sample task, which requires participants to notice and match the identity relation: for example, AA should match BB…

Memory Indexing: A Novel Method for Tracing Memory Processes in Complex Cognitive Tasks

ERIC Educational Resources Information Center

Renkewitz, Frank; Jahn, Georg

2012-01-01

We validate an eye-tracking method applicable for studying memory processes in complex cognitive tasks. The method is tested with a task on probabilistic inferences from memory. It provides valuable data on the time course of processing, thus clarifying previous results on heuristic probabilistic inference. Participants learned cue values of…

Elementary School Students' Strategic Learning: Does Task-Type Matter?

ERIC Educational Resources Information Center

Malmberg, Jonna; Järvelä, Sanna; Kirschner, Paul A.

2014-01-01

This study investigated what types of learning patterns and strategies elementary school students use to carry out ill- and well-structured tasks. Specifically, it was investigated which and when learning patterns actually emerge with respect to students' task solutions. The present study uses computer log file traces to investigate how…

Scanning Laser Infrared Molecular Spectrometer (SLIMS)

NASA Technical Reports Server (NTRS)

Scott, David C.; Rickey, Kelly; Ksendzov, Alexander; George, Warren P.; Aljabri, Abdullah S.; Steinkraus, Joel M.

2012-01-01

This prototype innovation is a novel design that achieves very long, effective laser path lengths that are able to yield ppb (parts per billion) and sub-ppb measurements of trace gases. SLIMS can also accommodate multiple laser channels covering a wide range of wavelengths, resulting in detection of more chemicals of interest. The mechanical design of the mirror cell allows for the large effective path length within a small footprint. The same design provides a robust structure that lends itself to being immune to some of the alignment challenges that similar cells face. By taking a hollow cylinder and by cutting an elliptically or spherically curved surface into its inner wall, the basic geometry of a reflecting ring is created. If the curved, inner surface is diamond-turned and highly polished, a surface that is very highly reflective can be formed. The surface finish can be further improved by adding a thin chrome or gold film over the surface. This creates a high-quality, curved, mirrored surface. A laser beam, which can be injected from a small bore hole in the wall of the cylinder, will be able to make many low-loss bounces around the ring, creating a large optical path length. The reflecting ring operates on the same principle as the Herriott cell. The difference exists in the mirror that doesn't have to be optically aligned, and which has a relatively large, internal surface area that lends itself to either open air or evacuated spectroscopic measurements. This solid, spherical ring mirror removes the possibility of mirror misalignment caused by thermal expansion or vibrations, because there is only a single, solid reflecting surface. Benefits of the reflecting ring come into play when size constraints reduce the size of the system, especially for space missions in which mass is at a premium.

Microfocusing options for the inelastic X-ray scattering beamline at sector 3 of the Advanced Photon Source.

PubMed

Alsmadi, A M; Alatas, A; Zhao, J Y; Hu, M Y; Yan, L; Alp, E E

2014-05-01

Synchrotron radiation from third-generation high-brilliance storage rings is an ideal source for X-ray microbeams. The aim of this paper is to describe a microfocusing scheme that combines both a toroidal mirror and Kirkpatrick-Baez (KB) mirrors for upgrading the existing optical system for inelastic X-ray scattering experiments at sector 3 of the Advanced Photon Source. SHADOW ray-tracing simulations without considering slope errors of both the toroidal mirror and KB mirrors show that this combination can provide a beam size of 4.5 µm (H) × 0.6 µm (V) (FWHM) at the end of the existing D-station (66 m from the source) with use of full beam transmission of up to 59%, and a beam size of 3.7 µm (H) × 0.46 µm (V) (FWHM) at the front-end of the proposed E-station (68 m from the source) with a transmission of up to 52%. A beam size of about 5 µm (H) × 1 µm (V) can be obtained, which is close to the ideal case, by using high-quality mirrors (with slope errors of less than 0.5 µrad r.m.s.). Considering the slope errors of the existing toroidal and KB mirrors (5 and 2.9 µrad r.m.s., respectively), the beam size grows to about 13.5 µm (H) × 6.3 µm (V) at the end of the D-station and to 12.0 µm (H) × 6.0 µm (V) at the front-end of the proposed E-station. The simulations presented here are compared with the experimental measurements that are significantly larger than the theoretical values even when slope error is included in the simulations. This is because of the experimental set-up that could not yet be optimized.

A space imaging concept based on a 4m structured spun-cast borosilicate monolithic primary mirror

NASA Astrophysics Data System (ADS)

West, S. C.; Bailey, S. H.; Bauman, S.; Cuerden, B.; Granger, Z.; Olbert, B. H.

2010-07-01

Lockheed Martin Corporation (LMC) tasked The University of Arizona Steward Observatory (UASO) to conduct an engineering study to examine the feasibility of creating a 4m space telescope based on mature borosilicate technology developed at the UASO for ground-based telescopes. UASO has completed this study and concluded that existing launch vehicles can deliver a 4m monolithic telescope system to a 500 km circular orbit and provide reliable imagery at NIIRS 7-8. An analysis of such an imager based on a lightweight, high-performance, structured 4m primary mirror cast from borosilicate glass is described. The relatively high CTE of this glass is used to advantage by maintaining mirror shape quality with a thermal figuring method. Placed in a 290 K thermal shroud (similar to the Hubble Space Telescope), the orbit averaged figure surface error is 6nm rms when earth-looking. Space-looking optical performance shows that a similar thermal conditioning scheme combined with a 270 K shroud achieves primary mirror distortion of 10 nm rms surface. Analysis shows that a 3-point bipod mount will provide launch survivability with ample margin. The primary mirror naturally maintains its shape at 1g allowing excellent end-to-end pre-launch testing with e.g. the LOTIS 6.5m Collimator. The telescope includes simple systems to measure and correct mirror shape and alignment errors incorporating technologies already proven on the LOTIS Collimator. We have sketched a notional earth-looking 4m telescope concept combined with a wide field TMA concept into a DELTA IV or ATLAS 552 EELV fairing. We have combined an initial analysis of launch and space performance of a special light-weighted honeycomb borosilicate mirror (areal density 95 kg/m2) with public domain information on the existing launch vehicles.

About Turn: How Object Orientation Affects Categorisation and Mental Rotation

ERIC Educational Resources Information Center

Milivojevic, Branka; Hamm, Jeff P.; Corballis, Michael C.

2011-01-01

High-density ERPs evoked by rotated alphanumeric characters were examined to determine how neural processing is affected by stimulus orientation during letter/digit classifications and during mirror/normal discriminations. The former task typically produces response times that are unaffected by stimulus orientation while the latter is thought to…

A simple optical system delivering a tunable micrometer pink beam that can compensate for heat-induced deformations

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

Reininger, Ruben; Liu, Zunping; Doumy, Gilles

2015-06-09

The radiation from an undulator reflected from one or more optical elements (usually termed `pink-beam') is used in photon-hungry experiments. The optical elements serve as a high-energy cutoff and for focusing purposes. One of the issues with this configuration is maintaining the focal spot dimension as the energy of the undulator is varied, since this changes the heat load absorbed by the first optical element. Finite-element analyses of the power absorbed by a side water-cooled mirror exposed to the radiation emitted by an undulator at the Advanced Photon Source (APS) and at the APS after the proposed upgrade (APSU) revealsmore » that the mirror deformation is very close to a convex cylinder creating a virtual source closer to the mirror than the undulator source. Here a simple optical system is described based on a Kirkpatrick–Baez pair which keeps the focus size to less than 2 µm (in the APSU case) with a working distance of 350 mm despite the heat-load-induced change in source distance. Detailed ray tracings at several photon energies for both the APS and APSU show that slightly decreasing the angle of incidence on the mirrors corrects the change in the `virtual' position of the source. The system delivers more than 70% of the first undulator harmonic with very low higher-orders contamination for energies between 5 and 10 keV.« less

Ray tracing on the MPP

NASA Technical Reports Server (NTRS)

Dorband, John E.

1987-01-01

Generating graphics to faithfully represent information can be a computationally intensive task. A way of using the Massively Parallel Processor to generate images by ray tracing is presented. This technique uses sort computation, a method of performing generalized routing interspersed with computation on a single-instruction-multiple-data (SIMD) computer.

NASA GTE TRACE-P Augmentation

NASA Technical Reports Server (NTRS)

Sandholm, Scott; Conners, Vickie (Technical Monitor)

2005-01-01

There were three major tasks and objectives that the Tropospheric Trace Gas and Airborne Measurement Group's (TTGAMG) worked on for different aspects of this grant: 1) Migrate the data acquisition system from HP-UX to Linux, thus reducing future costs as the result of software and operating system (OS) upgrades and improving upon usability as membership in the group changes; 2) Rework the Optical Parametric Oscillator (OPO) cavities. These are the OPOs that are integral to the Georgia Institute of Technology Airborne Laser Induced Fluorescent Experiment (GITALIFE) that the TTGAMG flew on TRACE-P. The objective was to improve upon optimizing the pump laser energy and narrowing the linewidth of the UV wavelength generated by the OPOs; 3) Improve and expand the interactive website on http://tmbk2.eas.gatech.edu by adding 3-D graphing, improve the response time for Joe Surfer Dude, improve performance, usability, and expand the database. If I were to assign a letter grade to each of the above tasks, I would give the TTGAMG two Bs and an A to the tasks listed above.

An integrated theory of attention and decision making in visual signal detection.

PubMed

Smith, Philip L; Ratcliff, Roger

2009-04-01

The simplest attentional task, detecting a cued stimulus in an otherwise empty visual field, produces complex patterns of performance. Attentional cues interact with backward masks and with spatial uncertainty, and there is a dissociation in the effects of these variables on accuracy and on response time. A computational theory of performance in this task is described. The theory links visual encoding, masking, spatial attention, visual short-term memory (VSTM), and perceptual decision making in an integrated dynamic framework. The theory assumes that decisions are made by a diffusion process driven by a neurally plausible, shunting VSTM. The VSTM trace encodes the transient outputs of early visual filters in a durable form that is preserved for the time needed to make a decision. Attention increases the efficiency of VSTM encoding, either by increasing the rate of trace formation or by reducing the delay before trace formation begins. The theory provides a detailed, quantitative account of attentional effects in spatial cuing tasks at the level of response accuracy and the response time distributions. (c) 2009 APA, all rights reserved

Employing Simulation to Evaluate Designs: The APEX Approach

NASA Technical Reports Server (NTRS)

Freed, Michael A.; Shafto, Michael G.; Remington, Roger W.; Null, Cynthia H. (Technical Monitor)

1998-01-01

The key innovations of APEX are its integrated approaches to task analysis, procedure definition, and intelligent, resource-constrained multi-tasking. This paper presents a step-by-step description of how APEX is used, from scenario development through trace analysis.

Analysis of the stress-deformed condition of the disassembly parabolic antenna

NASA Astrophysics Data System (ADS)

Odinets, M. N.; Kaygorodtseva, N. V.; Krysova, I. V.

2018-01-01

Active development of satellite communications and computer-aided design systems raises the problem of designing parabolic antennas on a new round of development. The aim of the work was to investigate the influence of the design of the mirror of a parabolic antenna on its endurance under wind load. The research task was an automated analysis of the stress-deformed condition of various designs of computer models of a paraboloid mirror (segmented or holistic) at modeling the exploitation conditions. The peculiarity of the research was that the assembly model of the antenna’s mirror was subjected to rigid connections on the contacting surfaces of the segments and only then the finite element grid was generated. The analysis showed the advantage of the design of the demountable antenna, which consists of cyclic segments, in front of the construction of the holistic antenna. Calculation of the stress-deformed condition of the antennas allows us to conclude that dividing the design of the antenna’s mirror on parabolic and cyclic segments increases it strength and rigidity. In the future, this can be used to minimize the mass of antenna and the dimensions of the disassembled antenna. The presented way of modeling a mirror of a parabolic antenna using to the method of the finite-element analysis can be used in the production of antennas.

Spatio-temporal dynamics of the mirror neuron system during social intentions.

PubMed

Cacioppo, Stephanie; Bolmont, Mylene; Monteleone, George

2017-10-27

Previous research has shown that specific goals and intentions influence a person's allocation of social attention. From a neural viewpoint, a growing body of evidence suggests that the inferior fronto-parietal network, including the mirror neuron system, plays a role in the planning and the understanding of motor intentions. However, it is unclear whether and when the mirror neuron system plays a role in social intentions. Combining a behavioral task with electrical neuroimaging in 22 healthy male participants, the current study investigates whether the temporal brain dynamic of the mirror neuron system differs during two types of social intentions i.e., lust vs. romantic intentions. Our results showed that 62% of the stimuli evoking lustful intentions also evoked romantic intentions, and both intentions were sustained by similar activations of the inferior frontal gyrus and the inferior parietal lobule/angular gyrus for the first 432 ms after stimulus onset. Intentions to not love or not lust, on the other hand, were characterized by earlier differential activations of the inferior fronto-parietal network i.e., as early as 244 ms after stimulus onset. These results suggest that the mirror neuron system may not only code for the motor correlates of intentions, but also for the social meaning of intentions and its valence at both early/automatic and later/more elaborative stages of information processing.

A cultural side effect: learning to read interferes with identity processing of familiar objects

PubMed Central

Kolinsky, Régine; Fernandes, Tânia

2014-01-01

Based on the neuronal recycling hypothesis (Dehaene and Cohen, 2007), we examined whether reading acquisition has a cost for the recognition of non-linguistic visual materials. More specifically, we checked whether the ability to discriminate between mirror images, which develops through literacy acquisition, interferes with object identity judgments, and whether interference strength varies as a function of the nature of the non-linguistic material. To these aims we presented illiterate, late literate (who learned to read at adult age), and early literate adults with an orientation-independent, identity-based same-different comparison task in which they had to respond “same” to both physically identical and mirrored or plane-rotated images of pictures of familiar objects (Experiment 1) or of geometric shapes (Experiment 2). Interference from irrelevant orientation variations was stronger with plane rotations than with mirror images, and stronger with geometric shapes than with objects. Illiterates were the only participants almost immune to mirror variations, but only for familiar objects. Thus, the process of unlearning mirror-image generalization, necessary to acquire literacy in the Latin alphabet, has a cost for a basic function of the visual ventral object recognition stream, i.e., identification of familiar objects. This demonstrates that neural recycling is not just an adaptation to multi-use but a process of at least partial exaptation. PMID:25400605

Effect of a mirror-like illusion on activation in the precuneus assessed with functional near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Mehnert, Jan; Brunetti, Maddalena; Steinbrink, Jens; Niedeggen, Michael; Dohle, Christian

2013-06-01

Mirror therapy is a therapy to treat patients with pain syndromes or hemiparesis after stroke. However, the underlying neurophysiologic mechanisms are not clearly understood. In order to determine the effect of a mirror-like illusion (MIR) on brain activity using functional near-infrared spectroscopy, 20 healthy right-handed subjects were examined. A MIR was induced by a digital horizontal inversion of the subjects' filmed hand. Optodes were placed on the primary motor cortex (M1) and the occipito-parietal cortex (precuneus, PC). Regions of interest (ROI) were defined a priori based on previous results of similar studies and confirmed by the analysis of effect sizes. Analysis of variance of the ROI signal revealed a dissociated pattern: at the PC, the MIR caused a significant inversion of a hemispheric lateralization opposite to the perceived hand, independent of the moving hand. In contrast, activity in M1 showed lateralization opposite to the moving hand, but revealed no mirror effect. These findings extend our understanding on interhemispheric rivalry and indicate that a MIR is integrated into visuomotor coordination similar to normal view, irrespective of the hand that is actually performing the task.

All-around viewing display system for group activity on life review therapy

NASA Astrophysics Data System (ADS)

Sakamoto, Kunio; Okumura, Mitsuru

2009-10-01

This paper describes 360 degree viewing display system that can be viewed from any direction. A conventional monitor display is viewed from one direction, i.e., the display has narrow viewing angle and observers cannot view the screen from the opposite side. To solve this problem, we developed the 360 degree viewing display for collaborative tasks on the round table. This developed 360 degree viewing system has a liquid crystal display screen and a 360 degree rotating table by motor. The principle is very simple. The screen of a monitor only rotates at a uniform speed, but the optical techniques are also utilized. Moreover, we have developed a floating 360 degree viewing display that can be viewed from any direction. This new viewing system has a display screen, a rotating table and dual parabolic mirrors. In order to float the only image screen above the table, the rotating mechanism works in the parabolic mirrors. Because the dual parabolic mirrors generate a "mirage" image over the upper mirror, observers can view a floating 2D image on the virtual screen in front of them. Then the observer can view a monitor screen at any position surrounding the round table.

Examining the Effects of Chromatic Aberration, Object Distance, and Eye Shape on Image-Formation in the Mirror-Based Eyes of the Bay Scallop Argopecten irradians.

PubMed

Speiser, Daniel I; Gagnon, Yakir Luc; Chhetri, Raghav K; Oldenburg, Amy L; Johnsen, Sönke

2016-11-01

The eyes of scallops form images using a concave spherical mirror and contain two separate retinas, one layered on top of the other. Behavioral and electrophysiological studies indicate that the images formed by these eyes have angular resolutions of about 2°. Based on previous ray-tracing models, it has been thought that the more distal of the two retinas lies near the focal point of the mirror and that the proximal retina, positioned closer to the mirror at the back of the eye, receives light that is out-of-focus. Here, we propose three mechanisms through which both retinas may receive focused light: (1) chromatic aberration produced by the lens may cause the focal points for longer and shorter wavelengths to fall near the distal and proximal retinas, respectively; (2) focused light from near and far objects may fall on the distal and proximal retinas, respectively; and (3) the eyes of scallops may be dynamic structures that change shape to determine which retina receives focused light. To test our hypotheses, we used optical coherence tomography (OCT), a method of near-infrared optical depth-ranging, to acquire virtual cross-sections of live, intact eyes from the bay scallop Argopecten irradians Next, we used a custom-built ray-tracing model to estimate the qualities of the images that fall on an eye's distal and proximal retinas as functions of the wavelengths of light entering the eye (400-700 nm), object distances (0.01-1 m), and the overall shape of the eye. When we assume 550 nm wavelength light and object distances greater than 0.01 m, our model predicts that the angular resolutions of the distal and proximal retinas are 2° and 7°, respectively. Our model also predicts that neither chromatic aberration nor differences in object distance lead to focused light falling on the distal and proximal retinas simultaneously. However, if scallops can manipulate the shapes of their eyes, perhaps through muscle contractions, we speculate that they may be able to influence the qualities of the images that fall on their proximal retinas and-to a lesser extent-those that fall on their distal retinas as well. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.

Examining the Effects of Chromatic Aberration, Object Distance, and Eye Shape on Image-Formation in the Mirror-Based Eyes of the Bay Scallop Argopecten irradians

PubMed Central

Speiser, Daniel I.; Gagnon, Yakir Luc; Chhetri, Raghav K.; Oldenburg, Amy L.; Johnsen, Sönke

2016-01-01

The eyes of scallops form images using a concave spherical mirror and contain two separate retinas, one layered on top of the other. Behavioral and electrophysiological studies indicate that the images formed by these eyes have angular resolutions of about 2°. Based on previous ray-tracing models, it has been thought that the more distal of the two retinas lies near the focal point of the mirror and that the proximal retina, positioned closer to the mirror at the back of the eye, receives light that is out-of-focus. Here, we propose three mechanisms through which both retinas may receive focused light: (1) chromatic aberration produced by the lens may cause the focal points for longer and shorter wavelengths to fall near the distal and proximal retinas, respectively; (2) focused light from near and far objects may fall on the distal and proximal retinas, respectively; and (3) the eyes of scallops may be dynamic structures that change shape to determine which retina receives focused light. To test our hypotheses, we used optical coherence tomography (OCT), a method of near-infrared optical depth-ranging, to acquire virtual cross-sections of live, intact eyes from the bay scallop Argopecten irradians. Next, we used a custom-built ray-tracing model to estimate the qualities of the images that fall on an eye’s distal and proximal retinas as functions of the wavelengths of light entering the eye (400–700 nm), object distances (0.01–1 m), and the overall shape of the eye. When we assume 550 nm wavelength light and object distances greater than 0.01 m, our model predicts that the angular resolutions of the distal and proximal retinas are 2° and 7°, respectively. Our model also predicts that neither chromatic aberration nor differences in object distance lead to focused light falling on the distal and proximal retinas simultaneously. However, if scallops can manipulate the shapes of their eyes, perhaps through muscle contractions, we speculate that they may be able to influence the qualities of the images that fall on their proximal retinas and—to a lesser extent—those that fall on their distal retinas as well. PMID:27549200

Altered Activation and Functional Asymmetry of Exner's Area but not the Visual Word Form Area in a Child with Sudden-onset, Persistent Mirror Writing.

PubMed

Linke, Annika; Roach-Fox, Elizabeth; Vriezen, Ellen; Prasad, Asuri Narayan; Cusack, Rhodri

2018-06-02

Mirror writing is often produced by healthy children during early acquisition of literacy, and has been observed in adults following neurological disorders or insults. The neural mechanisms responsible for involuntary mirror writing remain debated, but in healthy children, it is typically attributed to the delayed development of a process of overcoming mirror invariance while learning to read and write. We present an unusual case of sudden-onset, persistent mirror writing in a previously typical seven-year-old girl. Using her dominant right hand only, she copied and spontaneously produced all letters, words and sentences, as well as some numbers and objects, in mirror image. Additionally, she frequently misidentified letter orientations in perceptual assessments. Clinical, neuropsychological, and functional neuroimaging studies were carried out over sixteen months. Neurologic and ophthalmologic examinations and a standard clinical MRI scan of the head were normal. Neuropsychological testing revealed average scores on most tests of intellectual function, language function, verbal learning and memory. Visual perception and visual reasoning were average, with the exception of below average form constancy, and mild difficulties on some visual memory tests. Activation and functional connectivity of the reading and writing network was assessed with fMRI. During a reading task, the VWFA showed a strong response to words in mirror but not in normal letter orientation - similar to what has been observed in typically developing children previously - but activation was atypically reduced in right primary visual cortex and Exner's Area. Resting-state connectivity within the reading and writing network was similar to that of age-matched controls, but hemispheric asymmetry between the balance of motor-to-visual input was found for Exner's Area. In summary, this unusual case suggests that a disruption to visual-motor integration rather than to the VWFA can contribute to sudden-onset, persistent mirror writing in the absence of clinically detectable neurological insult. Copyright © 2018. Published by Elsevier Ltd.

The high energy astronomy observatories

NASA Technical Reports Server (NTRS)

Neighbors, A. K.; Doolittle, R. F.; Halpers, R. E.

1977-01-01

The forthcoming NASA project of orbiting High Energy Astronomy Observatories (HEAO's) designed to probe the universe by tracing celestial radiations and particles is outlined. Solutions to engineering problems concerning HEAO's which are integrated, yet built to function independently are discussed, including the onboard digital processor, mirror assembly and the thermal shield. The principle of maximal efficiency with minimal cost and the potential capability of the project to provide explanations to black holes, pulsars and gamma-ray bursts are also stressed. The first satellite is scheduled for launch in April 1977.

100 GB/S Time Division Multiplex (TDM) Access Nodes and Regenerators Based on Novel Loop Mirrors with High Nonlinearity Fibers

DTIC Science & Technology

2002-07-01

spectral components remain co-polarized. We confirmed that this was the case by passing the continuum through a polarizing beam splitter . The...propagation direction through polarization beam splitters and aligned along the other axis of the fiber. Co-propagating control and signal pulses...amplifier, PBS = polarization beam splitter . Figure 8. Eye diagram of header processor. This is the trace of the eye diagrams taken with the setup of Fig

Fabrication of high precision metallic freeform mirrors with magnetorheological finishing (MRF)

NASA Astrophysics Data System (ADS)

Beier, Matthias; Scheiding, Sebastian; Gebhardt, Andreas; Loose, Roman; Risse, Stefan; Eberhardt, Ramona; Tünnermann, Andreas

2013-09-01

The fabrication of complex shaped metal mirrors for optical imaging is a classical application area of diamond machining techniques. Aspherical and freeform shaped optical components up to several 100 mm in diameter can be manufactured with high precision in an acceptable amount of time. However, applications are naturally limited to the infrared spectral region due to scatter losses for shorter wavelengths as a result of the remaining periodic diamond turning structure. Achieving diffraction limited performance in the visible spectrum demands for the application of additional polishing steps. Magnetorheological Finishing (MRF) is a powerful tool to improve figure and finish of complex shaped optics at the same time in a single processing step. The application of MRF as a figuring tool for precise metal mirrors is a nontrivial task since the technology was primarily developed for figuring and finishing a variety of other optical materials, such as glasses or glass ceramics. In the presented work, MRF is used as a figuring tool for diamond turned aluminum lightweight mirrors with electroless nickel plating. It is applied as a direct follow-up process after diamond machining of the mirrors. A high precision measurement setup, composed of an interferometer and an advanced Computer Generated Hologram with additional alignment features, allows for precise metrology of the freeform shaped optics in short measuring cycles. Shape deviations less than 150 nm PV / 20 nm rms are achieved reliably for freeform mirrors with apertures of more than 300 mm. Characterization of removable and induced spatial frequencies is carried out by investigating the Power Spectral Density.

The role of handedness-dependent sensorimotor experience in the development of mirroring.

PubMed

Mori, Hirotaka; Yamamoto, Shinji; Aihara, Tsuyoshi; Uehara, Shintaro

2015-01-01

In daily life, we often try to learn motor actions by imitating others' actions. Motor imitation requires us to simultaneously map an observed action onto a motor program used to perform that action. This sensorimotor associative experience can plastically modulate the mirror property of the human mirror system, which has a role in matching observed actions directly with the observer's motor programs, to enhance the association between observed and performed actions. In the present study, we investigated the effects of handedness on the mirror property. Healthy left- and right-handed individuals performed a motor imitation task. They were required to imitate hand actions with their dominant hand as quickly and accurately as possible in response to pictures of a left and right hand. Reaction times (RTs) for imitating the hand actions were evaluated. Under the condition where the hand pictures were presented as if facing the participant, we found that, in left-handed participants, RTs for imitating right-handed actions were significantly shorter than those for imitating left-handed actions. Under the same conditions in right-handers, similar differences in RTs when presented left- and right-handed actions were not observed. These findings demonstrate that the imitative responses for left- and right-handed actions are differently facilitated depending on the handedness of the observer, indicating an effect of handedness on the development of mirror systems. The mirror property in left- and right-handers is likely modulated in a different manner by different sensorimotor associative experiences throughout their daily lives. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Cognitive Processing in Oral and Silent Reading Comprehension.

ERIC Educational Resources Information Center

Salasoo, Aita

1986-01-01

Reading rates and comprehension measures that probed recognition of various levels of text structure were collected for passages read orally and silently by 16 college students. Results showed that memory traces of text microstructure created in oral reading were accessed faster during memory-based comprehension tasks than traces established by…

Glass sample characterization

NASA Technical Reports Server (NTRS)

Ahmad, Anees

1990-01-01

The development of in-house integrated optical performance modelling capability at MSFC is described. This performance model will take into account the effects of structural and thermal distortions, as well as metrology errors in optical surfaces to predict the performance of large an complex optical systems, such as Advanced X-Ray Astrophysics Facility. The necessary hardware and software were identified to implement an integrated optical performance model. A number of design, development, and testing tasks were supported to identify the debonded mirror pad, and rebuilding of the Technology Mirror Assembly. Over 300 samples of Zerodur were prepared in different sizes and shapes for acid etching, coating, and polishing experiments to characterize the subsurface damage and stresses produced by the grinding and polishing operations.

A hybrid method for X-ray optics simulation: combining geometric ray-tracing and wavefront propagation

DOE PAGES

Shi, Xianbo; Reininger, Ruben; Sanchez del Rio, Manuel; ...

2014-05-15

A new method for beamline simulation combining ray-tracing and wavefront propagation is described. The 'Hybrid Method' computes diffraction effects when the beam is clipped by an aperture or mirror length and can also simulate the effect of figure errors in the optical elements when diffraction is present. The effect of different spatial frequencies of figure errors on the image is compared withSHADOWresults pointing to the limitations of the latter. The code has been benchmarked against the multi-electron version ofSRWin one dimension to show its validity in the case of fully, partially and non-coherent beams. The results demonstrate that the codemore » is considerably faster than the multi-electron version ofSRWand is therefore a useful tool for beamline design and optimization.« less

Neural Mechanism of Inferring Person's Inner Attitude towards Another Person through Observing the Facial Affect in an Emotional Context.

PubMed

Kim, Ji-Woong; Kim, Jae-Jin; Jeong, Bumseok; Kim, Sung-Eun; Ki, Seon Wan

2010-03-01

The goal of the present study was to identify the brain mechanism involved in the attribution of person's attitude toward another person, using facial affective pictures and pictures displaying an affectively-loaded situation. Twenty four right-handed healthy subjects volunteered for our study. We used functional magnetic resonance imaging (MRI) to examine brain activation during attitude attribution task as compared to gender matching tasks. We identified activation in the left inferior frontal cortex, left superior temporal sulcus, and left inferior parietal lobule during the attitude attribution task, compared to the gender matching task. This study suggests that mirror neuron system and ventrolateral inferior frontal cortex play a critical role in the attribution of a person's inner attitude towards another person in an emotional situation.

Standardization of Solar Mirror Reflectance Measurements - Round Robin Test: Preprint

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

Meyen, S.; Lupfert, E.; Fernandez-Garcia, A.

2010-10-01

Within the SolarPaces Task III standardization activities, DLR, CIEMAT, and NREL have concentrated on optimizing the procedure to measure the reflectance of solar mirrors. From this work, the laboratories have developed a clear definition of the method and requirements needed of commercial instruments for reliable reflectance results. A round robin test was performed between the three laboratories with samples that represent all of the commercial solar mirrors currently available for concentrating solar power (CSP) applications. The results show surprisingly large differences in hemispherical reflectance (sh) of 0.007 and specular reflectance (ss) of 0.004 between the laboratories. These differences indicate themore » importance of minimum instrument requirements and standardized procedures. Based on these results, the optimal procedure will be formulated and validated with a new round robin test in which a better accuracy is expected. Improved instruments and reference standards are needed to reach the necessary accuracy for cost and efficiency calculations.« less

AMTD: update of engineering specifications derived from science requirements for future UVOIR space telescopes

NASA Astrophysics Data System (ADS)

Stahl, H. Philip; Postman, Marc; Mosier, Gary; Smith, W. Scott; Blaurock, Carl; Ha, Kong; Stark, Christopher C.

2014-08-01

The Advance Mirror Technology Development (AMTD) project is in Phase 2 of a multiyear effort, initiated in FY12, to mature by at least a half TRL step six critical technologies required to enable 4 meter or larger UVOIR space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND provide a high-performance low-cost low-risk system. To give the science community options, we are pursuing multiple technology paths. A key task is deriving engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicles and their mass and volume constraints. A key finding of this effort is that the science requires an 8 meter or larger aperture telescope.

Mirror neuron dysfunction in autism spectrum disorders.

PubMed

Perkins, Tom; Stokes, Mark; McGillivray, Jane; Bittar, Richard

2010-10-01

Autism spectrum disorders (ASDs) are developmental conditions characterized by deficits in social interaction, verbal and nonverbal communication and obsessive/stereotyped patterns of behaviour. Although there is no reliable neurophysiological marker associated with ASDs, dysfunction of the parieto-frontal mirror neuron system has been suggested as a disturbance linked to the disorder. Mirror neurons (MNs) are visuomotor neurons which discharge both when performing and observing a goal directed action. Research suggests MNs may have a role in imitation, empathy, theory of mind and language. Although the research base is small, evidence from functional MRI, transcranial magnetic stimulation, and an electroencephalographic component called the mu rhythm suggests MNs are dysfunctional in subjects with ASD. These deficits are more pronounced when ASD subjects complete tasks with social relevance, or that are emotional in nature. Promising research has identified that interventions targeting MN related functions such as imitation can improve social functioning in ASDs. Boosting the function of MNs may improve the prognosis of ASDs, and contribute to diagnostic clarity. Copyright 2010 Elsevier Ltd. All rights reserved.

AMTD: Update of Engineering Specifications Derived from Science Requirements for Future UVOIR Space Telescopes

NASA Technical Reports Server (NTRS)

Stahl, H. Philip; Postman, Marc; Mosier, Gary; Smith, W. Scott; Blaurock, Carl; Ha, Kong; Stark, Christopher C.

2014-01-01

The Advance Mirror Technology Development (AMTD) project is in Phase 2 of a multiyear effort, initiated in FY12, to mature by at least a half TRL step six critical technologies required to enable 4 meter or larger UVOIR space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND provide a high-performance low-cost low-risk system. To give the science community options, we are pursuing multiple technology paths. A key task is deriving engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicles and their mass and volume constraints. A key finding of this effort is that the science requires an 8 meter or larger aperture telescope

Lateral Biases and Reading Direction: A Dissociation between Aesthetic Preference and Line Bisection

ERIC Educational Resources Information Center

Ishii, Yukiko; Okubo, Matia; Nicholls, Michael E. R.; Imai, Hisato

2011-01-01

Perceptual asymmetries for tasks involving aesthetic preference or line bisection can be affected by asymmetrical neurological mechanisms or left/right reading habits. This study investigated the relative contribution of these mechanisms in 100 readers of Japanese and English. Participants made aesthetic judgments between pairs of mirror-reversed…

Sex differences in chronometric mental rotation with human bodies.

PubMed

Voyer, Daniel; Jansen, Petra

2016-11-01

The present experiment investigated sex differences across stimulus types in a chronometric mental rotation task. The working hypothesis was that human bodies as stimuli would reduce the magnitude of sex differences compared to cubes as stimuli, from the embodied cognition perspective. One hundred and twenty participants, 60 men and 60 women solved chronometric mental rotation items with Shepard-Metzler cube figures, head-cubes, and human bodies, all designed so that they were similar in shape. Two figures of a given stimulus type were presented on the screen and participants had to judge if both items were mirrored or non-mirrored. Results showed better mental rotation performance with human bodies than with other types of stimuli for both sexes, although the effect of stimulus type was more pronounced in men than in women. Furthermore, regardless of stimulus type, men were more accurate than women. Altogether, the results suggest that sex differences are not reduced when human bodies are used as stimuli in a chronometric task. Implications for accounts of sex differences in mental rotations are discussed.

Design of a Virtual Player for Joint Improvisation with Humans in the Mirror Game

PubMed Central

Zhai, Chao; Alderisio, Francesco; Tsaneva-Atanasova, Krasimira; di Bernardo, Mario

2016-01-01

Joint improvisation is often observed among humans performing joint action tasks. Exploring the underlying cognitive and neural mechanisms behind the emergence of joint improvisation is an open research challenge. This paper investigates jointly improvised movements between two participants in the mirror game, a paradigmatic joint task example. First, experiments involving movement coordination of different dyads of human players are performed in order to build a human benchmark. No designation of leader and follower is given beforehand. We find that joint improvisation is characterized by the lack of a leader and high levels of movement synchronization. Then, a theoretical model is proposed to capture some features of their interaction, and a set of experiments is carried out to test and validate the model ability to reproduce the experimental observations. Furthermore, the model is used to drive a computer avatar able to successfully improvise joint motion with a human participant in real time. Finally, a convergence analysis of the proposed model is carried out to confirm its ability to reproduce joint movements between the participants. PMID:27123927

Design of a Virtual Player for Joint Improvisation with Humans in the Mirror Game.

PubMed

Zhai, Chao; Alderisio, Francesco; Słowiński, Piotr; Tsaneva-Atanasova, Krasimira; di Bernardo, Mario

2016-01-01

Joint improvisation is often observed among humans performing joint action tasks. Exploring the underlying cognitive and neural mechanisms behind the emergence of joint improvisation is an open research challenge. This paper investigates jointly improvised movements between two participants in the mirror game, a paradigmatic joint task example. First, experiments involving movement coordination of different dyads of human players are performed in order to build a human benchmark. No designation of leader and follower is given beforehand. We find that joint improvisation is characterized by the lack of a leader and high levels of movement synchronization. Then, a theoretical model is proposed to capture some features of their interaction, and a set of experiments is carried out to test and validate the model ability to reproduce the experimental observations. Furthermore, the model is used to drive a computer avatar able to successfully improvise joint motion with a human participant in real time. Finally, a convergence analysis of the proposed model is carried out to confirm its ability to reproduce joint movements between the participants.

About turn: how object orientation affects categorisation and mental rotation.

PubMed

Milivojevic, Branka; Hamm, Jeff P; Corballis, Michael C

2011-11-01

High-density ERPs evoked by rotated alphanumeric characters were examined to determine how neural processing is affected by stimulus orientation during letter/digit classifications and during mirror/normal discriminations. The former task typically produces response times that are unaffected by stimulus orientation while the latter is thought to require mental rotation. Sensitivity to orientation was first observed around 100-140 ms and this effect was attributed to differences in low-level features between vertical and oblique orientations. Subsequently, character misorientation amplified the N170, a neural marker of object classification, between 160 and 220 ms. Top-down processing is reflected in the ERPs beginning at 280-320 ms and this time range may reflect binding of ventral and dorsal stream information. In the case of mirror-normal discrimination these top-down processes can lead to mental rotation between 340 and 700 ms. Therefore, although neural processing reflects object orientation, these effects do not translate into increases in reaction-times or impaired accuracy for categorisation, and precede those that do in the mental-rotation task. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quantitative assessment of airborne exposures generated during common cleaning tasks: a pilot study

PubMed Central

2010-01-01

Background A growing body of epidemiologic evidence suggests an association between exposure to cleaning products with asthma and other respiratory disorders. Thus far, these studies have conducted only limited quantitative exposure assessments. Exposures from cleaning products are difficult to measure because they are complex mixtures of chemicals with a range of physicochemical properties, thus requiring multiple measurement techniques. We conducted a pilot exposure assessment study to identify methods for assessing short term, task-based airborne exposures and to quantitatively evaluate airborne exposures associated with cleaning tasks simulated under controlled work environment conditions. Methods Sink, mirror, and toilet bowl cleaning tasks were simulated in a large ventilated bathroom and a small unventilated bathroom using a general purpose, a glass, and a bathroom cleaner. All tasks were performed for 10 minutes. Airborne total volatile organic compounds (TVOC) generated during the tasks were measured using a direct reading instrument (DRI) with a photo ionization detector. Volatile organic ingredients of the cleaning mixtures were assessed utilizing an integrated sampling and analytic method, EPA TO-17. Ammonia air concentrations were also measured with an electrochemical sensor embedded in the DRI. Results Average TVOC concentrations calculated for 10 minute tasks ranged 0.02 - 6.49 ppm and the highest peak concentrations observed ranged 0.14-11 ppm. TVOC time concentration profiles indicated that exposures above background level remained present for about 20 minutes after cessation of the tasks. Among several targeted VOC compounds from cleaning mixtures, only 2-BE was detectable with the EPA method. The ten minute average 2- BE concentrations ranged 0.30 -21 ppm between tasks. The DRI underestimated 2-BE exposures compared to the results from the integrated method. The highest concentration of ammonia of 2.8 ppm occurred during mirror cleaning. Conclusions Our results indicate that airborne exposures from short-term cleaning tasks can remain in the air even after tasks' cessation, suggesting potential exposures to anyone entering the room shortly after cleaning. Additionally, 2-BE concentrations from cleaning could approach occupational exposure limits and warrant further investigation. Measurement methods applied in this study can be useful for workplace assessment of airborne exposures during cleaning, if the limitations identified here are addressed. PMID:21118559

In vivo retinal imaging for fixational eye motion detection using a high-speed digital micromirror device (DMD)-based ophthalmoscope.

PubMed

Vienola, Kari V; Damodaran, Mathi; Braaf, Boy; Vermeer, Koenraad A; de Boer, Johannes F

2018-02-01

Retinal motion detection with an accuracy of 0.77 arcmin corresponding to 3.7 µm on the retina is demonstrated with a novel digital micromirror device based ophthalmoscope. By generating a confocal image as a reference, eye motion could be measured from consecutively measured subsampled frames. The subsampled frames provide 7.7 millisecond snapshots of the retina without motion artifacts between the image points of the subsampled frame, distributed over the full field of view. An ophthalmoscope pattern projection speed of 130 Hz enabled a motion detection bandwidth of 65 Hz. A model eye with a scanning mirror was built to test the performance of the motion detection algorithm. Furthermore, an in vivo motion trace was obtained from a healthy volunteer. The obtained eye motion trace clearly shows the three main types of fixational eye movements. Lastly, the obtained eye motion trace was used to correct for the eye motion in consecutively obtained subsampled frames to produce an averaged confocal image correct for motion artefacts.

In vivo retinal imaging for fixational eye motion detection using a high-speed digital micromirror device (DMD)-based ophthalmoscope

PubMed Central

Vienola, Kari V.; Damodaran, Mathi; Braaf, Boy; Vermeer, Koenraad A.; de Boer, Johannes F.

2018-01-01

Retinal motion detection with an accuracy of 0.77 arcmin corresponding to 3.7 µm on the retina is demonstrated with a novel digital micromirror device based ophthalmoscope. By generating a confocal image as a reference, eye motion could be measured from consecutively measured subsampled frames. The subsampled frames provide 7.7 millisecond snapshots of the retina without motion artifacts between the image points of the subsampled frame, distributed over the full field of view. An ophthalmoscope pattern projection speed of 130 Hz enabled a motion detection bandwidth of 65 Hz. A model eye with a scanning mirror was built to test the performance of the motion detection algorithm. Furthermore, an in vivo motion trace was obtained from a healthy volunteer. The obtained eye motion trace clearly shows the three main types of fixational eye movements. Lastly, the obtained eye motion trace was used to correct for the eye motion in consecutively obtained subsampled frames to produce an averaged confocal image correct for motion artefacts. PMID:29552396

Perirhinal and Postrhinal, but Not Lateral Entorhinal, Cortices Are Essential for Acquisition of Trace Eyeblink Conditioning

ERIC Educational Resources Information Center

Suter, Eugenie E.; Weiss, Craig; Disterhoft, John F.

2013-01-01

The acquisition of temporal associative tasks such as trace eyeblink conditioning is hippocampus-dependent, while consolidated performance is not. The parahippocampal region mediates much of the input and output of the hippocampus, and perirhinal (PER) and entorhinal (EC) cortices support persistent spiking, a possible mediator of temporal…

On the Performance Characteristics of Latent-Factor and Knowledge Tracing Models

ERIC Educational Resources Information Center

Klingler, Severin; Käser, Tanja; Solenthaler, Barbara; Gross, Markus

2015-01-01

Modeling student knowledge is a fundamental task of an intelligent tutoring system. A popular approach for modeling the acquisition of knowledge is Bayesian Knowledge Tracing (BKT). Various extensions to the original BKT model have been proposed, among them two novel models that unify BKT and Item Response Theory (IRT). Latent Factor Knowledge…

Complementary Machine Intelligence and Human Intelligence in Virtual Teaching Assistant for Tutoring Program Tracing

ERIC Educational Resources Information Center

Chou, Chih-Yueh; Huang, Bau-Hung; Lin, Chi-Jen

2011-01-01

This study proposes a virtual teaching assistant (VTA) to share teacher tutoring tasks in helping students practice program tracing and proposes two mechanisms of complementing machine intelligence and human intelligence to develop the VTA. The first mechanism applies machine intelligence to extend human intelligence (teacher answers) to evaluate…

Decay of Iconic Memory Traces Is Related to Psychometric Intelligence: A Fixed-Links Modeling Approach

ERIC Educational Resources Information Center

Miller, Robert; Rammsayer, Thomas H.; Schweizer, Karl; Troche, Stefan J.

2010-01-01

Several memory processes have been examined regarding their relation to psychometric intelligence with the exception of sensory memory. This study examined the relation between decay of iconic memory traces, measured with a partial-report task, and psychometric intelligence, assessed with the Berlin Intelligence Structure test, in 111…

The origin of children's implanted false memories: memory traces or compliance?

PubMed

Otgaar, Henry; Verschuere, Bruno; Meijer, Ewout H; van Oorsouw, Kim

2012-03-01

A longstanding question in false memory research is whether children's implanted false memories represent actual memory traces or merely result from compliance. The current study examined this question using a response latency based deception task. Forty-five 8-year-old children received narratives about a true (first day at school) and false event (hot air balloon ride). Across two interviews, 58/32% of the participants developed a partial/full false memory. Interestingly, these children also showed higher false recall on an unrelated DRM paradigm compared to children without a false memory. The crucial finding, however, was that the results of the deception task revealed that children with partial and full false memories were faster to confirm than to deny statements relating to the false event. This indicates that children's implanted false memories reflect actual memory traces, and are unlikely to be explained by mere compliance. Copyright © 2012 Elsevier B.V. All rights reserved.

Impaired capacity of cerebellar patients to perceive and learn two-dimensional shapes based on kinesthetic cues.

PubMed

Shimansky, Y; Saling, M; Wunderlich, D A; Bracha, V; Stelmach, G E; Bloedel, J R

1997-01-01

This study addresses the issue of the role of the cerebellum in the processing of sensory information by determining the capability of cerebellar patients to acquire and use kinesthetic cues received via the active or passive tracing of an irregular shape while blindfolded. Patients with cerebellar lesions and age-matched healthy controls were tested on four tasks: (1) learning to discriminate a reference shape from three others through the repeated tracing of the reference template; (2) reproducing the reference shape from memory by drawing blindfolded; (3) performing the same task with vision; and (4) visually recognizing the reference shape. The cues used to acquire and then to recognize the reference shape were generated under four conditions: (1) "active kinesthesia," in which cues were acquired by the blindfolded subject while actively tracing a reference template; (2) "passive kinesthesia," in which the tracing was performed while the hand was guided passively through the template; (3) "sequential vision," in which the shape was visualized by the serial exposure of small segments of its outline; and (4) "full vision," in which the entire shape was visualized. The sequential vision condition was employed to emulate the sequential way in which kinesthetic information is acquired while tracing the reference shape. The results demonstrate a substantial impairment of cerebellar patients in their capability to perceive two-dimensional irregular shapes based only on kinesthetic cues. There also is evidence that this deficit in part relates to a reduced capacity to integrate temporal sequences of sensory cues into a complete image useful for shape discrimination tasks or for reproducing the shape through drawing. Consequently, the cerebellum has an important role in this type of sensory information processing even when it is not directly associated with the execution of movements.

Intact mirror mechanisms for automatic facial emotions in children and adolescents with autism spectrum disorder.

PubMed

Schulte-Rüther, Martin; Otte, Ellen; Adigüzel, Kübra; Firk, Christine; Herpertz-Dahlmann, Beate; Koch, Iring; Konrad, Kerstin

2017-02-01

It has been suggested that an early deficit in the human mirror neuron system (MNS) is an important feature of autism. Recent findings related to simple hand and finger movements do not support a general dysfunction of the MNS in autism. Studies investigating facial actions (e.g., emotional expressions) have been more consistent, however, mostly relied on passive observation tasks. We used a new variant of a compatibility task for the assessment of automatic facial mimicry responses that allowed for simultaneous control of attention to facial stimuli. We used facial electromyography in 18 children and adolescents with Autism spectrum disorder (ASD) and 18 typically developing controls (TDCs). We observed a robust compatibility effect in ASD, that is, the execution of a facial expression was facilitated if a congruent facial expression was observed. Time course analysis of RT distributions and comparison to a classic compatibility task (symbolic Simon task) revealed that the facial compatibility effect appeared early and increased with time, suggesting fast and sustained activation of motor codes during observation of facial expressions. We observed a negative correlation of the compatibility effect with age across participants and in ASD, and a positive correlation between self-rated empathy and congruency for smiling faces in TDC but not in ASD. This pattern of results suggests that basic motor mimicry is intact in ASD, but is not associated with complex social cognitive abilities such as emotion understanding and empathy. Autism Res 2017, 10: 298-310. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

C957T polymorphism of the dopamine D2 receptor gene is associated with motor learning and heart rate.

PubMed

Huertas, E; Bühler, K-M; Echeverry-Alzate, V; Giménez, T; López-Moreno, J A

2012-08-01

Genetic variants that are related to the dopaminergic system have been frequently found to be associated with various neurological and mental disorders. Here, we studied the relationships between some of these genetic variants and some cognitive and psychophysiological processes that are implicated in such disorders. Two single nucleotide polymorphisms were chosen: one in the dopamine D2 receptor gene (rs6277-C957T) and one in the catechol-O-methyltransferase gene (rs4680-Val158Met), which is involved in the metabolic degradation of dopamine. The performance of participants on two long-term memory tasks was assessed: free recall (declarative memory) and mirror drawing (procedural motor learning). Heart rate (HR) was also monitored during the initial trials of the mirror-drawing task, which is considered to be a laboratory middle-stress generator (moderate stress), and during a rest period (low stress). Data were collected from 213 healthy Caucasian university students. The C957T C homozygous participants showed more rapid learning than the T allele carriers in the procedural motor learning task and smaller differences in HR between the moderate- and the low-stress conditions. These results provide useful information regarding phenotypic variance in both healthy individuals and patients. © 2012 The Authors. Genes, Brain and Behavior © 2012 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.

Effects of OEF/OIF-Related Physical and Emotional Co-Morbidities on Associative Learning: Concurrent Delay and Trace Eyeblink Classical Conditioning

PubMed Central

McGlinchey, Regina E.; Fortier, Catherine B.; Venne, Jonathan R.; Maksimovskiy, Arkadiy L.; Milberg, William P.

2014-01-01

This study examined the performance of veterans and active duty personnel who served in Operation Enduring Freedom and/or Operation Iraqi Freedom (OEF/OIF) on a basic associative learning task. Eighty-eight individuals participated in this study. All received a comprehensive clinical evaluation to determine the presence and severity of posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI). The eyeblink conditioning task was composed of randomly intermixed delay and trace conditioned stimulus (CS) and unconditioned stimulus (US) pairs (acquisition) followed by a series of CS only trials (extinction). Results revealed that those with a clinical diagnosis of PTSD or a diagnosis of PTSD with comorbid mTBI acquired delay and trace conditioned responses (CRs) to levels and at rates similar to a deployed control group, thus suggesting intact basic associative learning. Differential extinction impairment was observed in the two clinical groups. Acquisition of CRs for both delay and trace conditioning, as well as extinction of trace CRs, was associated with alcoholic behavior across all participants. These findings help characterize the learning and memory function of individuals with PTSD and mTBI from OEF/OIF and raise the alarming possibility that the use of alcohol in this group may lead to more significant cognitive dysfunction. PMID:24625622

Evaluation of ITER MSE Viewing Optics

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

Allen, S; Lerner, S; Morris, K

2007-03-26

The Motional Stark Effect (MSE) diagnostic on ITER determines the local plasma current density by measuring the polarization angle of light resulting from the interaction of a high energy neutral heating beam and the tokamak plasma. This light signal has to be transmitted from the edge and core of the plasma to a polarization analyzer located in the port plug. The optical system should either preserve the polarization information, or it should be possible to reliably calibrate any changes induced by the optics. This LLNL Work for Others project for the US ITER Project Office (USIPO) is focused on themore » design of the viewing optics for both the edge and core MSE systems. Several design constraints were considered, including: image quality, lack of polarization aberrations, ease of construction and cost of mirrors, neutron shielding, and geometric layout in the equatorial port plugs. The edge MSE optics are located in ITER equatorial port 3 and view Heating Beam 5, and the core system is located in equatorial port 1 viewing heating beam 4. The current work is an extension of previous preliminary design work completed by the ITER central team (ITER resources were not available to complete a detailed optimization of this system, and then the MSE was assigned to the US). The optimization of the optical systems at this level was done with the ZEMAX optical ray tracing code. The final LLNL designs decreased the ''blur'' in the optical system by nearly an order of magnitude, and the polarization blur was reduced by a factor of 3. The mirror sizes were reduced with an estimated cost savings of a factor of 3. The throughput of the system was greater than or equal to the previous ITER design. It was found that optical ray tracing was necessary to accurately measure the throughput. Metal mirrors, while they can introduce polarization aberrations, were used close to the plasma because of the anticipated high heat, particle, and neutron loads. These mirrors formed an intermediate image that then was relayed out of the port plug with more ideal (dielectric) mirrors. Engineering models of the optics, port plug, and neutral beam geometry were also created, using the CATIA ITER models. Two video conference calls with the USIPO provided valuable design guidelines, such as the minimum distance of the first optic from the plasma. A second focus of the project was the calibration of the system. Several different techniques are proposed, both before and during plasma operation. Fixed and rotatable polarizers would be used to characterize the system in the no-plasma case. Obtaining the full modulation spectrum from the polarization analyzer allows measurement of polarization effects and also MHD plasma phenomena. Light from neutral beam interaction with deuterium gas (no plasma) has been found useful to determine the wavelength of each spatial channel. The status of the optical design for the edge (upper) and core (lower) systems is included in the following figure. Several issues should be addressed by a follow-on study, including whether the optical labyrinth has sufficient neutron shielding and a detailed polarization characterization of actual mirrors.« less

Ultra-precision turning of complex spiral optical delay line

NASA Astrophysics Data System (ADS)

Zhang, Xiaodong; Li, Po; Fang, Fengzhou; Wang, Qichang

2011-11-01

Optical delay line (ODL) implements the vertical or depth scanning of optical coherence tomography, which is the most important factor affecting the scanning resolution and speed. The spinning spiral mirror is found as an excellent optical delay device because of the high-speed and high-repetition-rate. However, it is one difficult task to machine the mirror due to the special shape and precision requirement. In this paper, the spiral mirror with titled parabolic generatrix is proposed, and the ultra-precision turning method is studied for its machining using the spiral mathematic model. Another type of ODL with the segmental shape is also introduced and machined to make rotation balance for the mass equalization when scanning. The efficiency improvement is considered in details, including the rough cutting with the 5- axis milling machine, the machining coordinates unification, and the selection of layer direction in turning. The onmachine measuring method based on stylus gauge is designed to analyze the shape deviation. The air bearing is used as the measuring staff and the laser interferometer sensor as the position sensor, whose repeatability accuracy is proved up to 10nm and the stable feature keeps well. With this method developed, the complex mirror with nanometric finish of 10.7nm in Ra and the form error within 1um are achieved.

Selective Effects of Motor Expertise in Mental Body Rotation Tasks: Comparing Object-Based and Perspective Transformations

ERIC Educational Resources Information Center

Steggemann, Yvonne; Engbert, Kai; Weigelt, Matthias

2011-01-01

Brain imaging studies provide strong evidence for the involvement of the human mirror system during the observation of complex movements, depending on the individual's motor expertise. Here, we ask the question whether motor expertise not only affects perception while observing movements, but also benefits perception while solving mental rotation…

Much Needed Structure [Structured Decision-Making with DMRCS. Define-Measure-Reduce-Combine-Select

DOE PAGES

Anderson-Cook, Christine M.; Lu, Lu

2015-10-01

We have described a new DMRCS process for structured decision making, which mirrors the approach of the DMAIC process which has become so popular within Lean Six Sigma. By dividing a complex often unstructured process into distinct steps, we hope to have made the task of balancing multiple competing objectives less daunting.

Susceptibility to false memories in patients with ACoA aneurysm.

PubMed

Borsutzky, Sabine; Fujiwara, Esther; Brand, Matthias; Markowitsch, Hans J

2010-08-01

We examined ACoA patients regarding their susceptibility to a range of false memory phenomena. We targeted provoked confabulation, false recall and false recognition in the Deese-Roediger-McDermott-paradigm (DRM-paradigm) as well as false recognition in a mirror reading task. ACoA patients produced more provoked confabulations and more false recognition in mirror reading than comparison subjects. Conversely, false recall/false recognition in the DRM-paradigm were similar in patients and controls. Whereas the former two indices of false memories were correlated, no relationship was revealed with the DRM-paradigm. Our results suggest that rupture of ACoA aneurysm leads to an increased susceptibility to a subset of false memories types. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Pretrial Functional Connectivity Differentiates Behavioral Outcomes during Trace Eyeblink Conditioning in the Rabbit

ERIC Educational Resources Information Center

Schroeder, Matthew P.; Weiss, Craig; Procissi, Daniel; Wang, Lei; Disterhoft, John F.

2016-01-01

Fluctuations in neural activity can produce states that facilitate and accelerate task-related performance. Acquisition of trace eyeblink conditioning (tEBC) in the rabbit is enhanced when trials are contingent on optimal pretrial activity in the hippocampus. Other regions which are essential for whisker-signaled tEBC, such as the cerebellar…

Cognitive Demand of Model Tracing Tutor Tasks: Conceptualizing and Predicting How Deeply Students Engage

ERIC Educational Resources Information Center

Kessler, Aaron M.; Stein, Mary Kay; Schunn, Christian D.

2015-01-01

Model tracing tutors represent a technology designed to mimic key elements of one-on-one human tutoring. We examine the situations in which such supportive computer technologies may devolve into mindless student work with little conceptual understanding or student development. To analyze the support of student intellectual work in the model…

Emotional task management: neural correlates of switching between affective and non-affective task-sets

PubMed Central

Reeck, Crystal

2015-01-01

Although task-switching has been investigated extensively, its interaction with emotionally salient task content remains unclear. Prioritized processing of affective stimulus content may enhance accessibility of affective task-sets and generate increased interference when switching between affective and non-affective task-sets. Previous research has demonstrated that more dominant task-sets experience greater switch costs, as they necessitate active inhibition during performance of less entrenched tasks. Extending this logic to the affective domain, the present experiment examined (a) whether affective task-sets are more dominant than non-affective ones, and (b) what neural mechanisms regulate affective task-sets, so that weaker, non-affective task-sets can be executed. While undergoing functional magnetic resonance imaging, participants categorized face stimuli according to either their gender (non-affective task) or their emotional expression (affective task). Behavioral results were consistent with the affective task dominance hypothesis: participants were slower to switch to the affective task, and cross-task interference was strongest when participants tried to switch from the affective to the non-affective task. These behavioral costs of controlling the affective task-set were mirrored in the activation of a right-lateralized frontostriatal network previously implicated in task-set updating and response inhibition. Connectivity between amygdala and right ventrolateral prefrontal cortex was especially pronounced during cross-task interference from affective features. PMID:25552571

Precision gimballed mirror control in remote sensing LIDAR for environmental monitoring

NASA Astrophysics Data System (ADS)

Singh, Ravindra; Mudgil, Ashwani; Prakash, Chandra; Pal, Suranjan

2006-12-01

Differential Absorption Lidar (DIAL) Systems are advantageously used to detect and measure very small concentrations of trace gases in the atmosphere. There is a requirement to interrogate and search for the presence of one or more of toxic agents out of a large number (about 20 or so) of possible agents at distances up to several kilometers with the help of a ground-based multi-wavelength DIAL system employing pulsed, tunable laser sources in the wavelength bands of 2-5 micron and 9.2-10.8 micron. The Laser beams from the two sources are directed in the atmosphere with a predefined divergence to scan the atmosphere. Two methodologies can be implemented to provide the beam steering, one is to mount the entire telescope of transmitting and receiving channel on to a motorized gimbal platform and second is to keep the optical telescope stationary and use a slewing mirror to steer the beam in required direction. The first scheme is named as mass control and second scheme is called mirror control. Both the schemes have relative advantages and disadvantages and in the present DIAL application second scheme is being adopted. The present opto-mechanical configuration of DIAL system employs a 700 x 500 mm 2 (Elliptical) steering mirror for transmitting the collimated beams in a required direction and receiving the reflected beam as well. In the receiving channel a Telescope is used which collects the return beam and focuses the same on to a detector. The slewing mirror is housed in a gimbal mount having a sufficient FOR (Field of Regard) in Azimuth and elevation plane. The paper describes the modeling and simulation of Opto-mechanical and servo-mechanical subsystems of precision gimbaled mirror and also discusses the issues related to design of control system. The requirement specifications in regard to field of regard, slew rates 5°/s, scanning rates 1°/s are to be met with stringent beam pointing and scanning accuracies. The design of this system is categorized as multidisciplinary problem. The design parameters obtained from opto-mechanical analysis forms the input for control system design. The design of control system is carried out using conventional design methodologies.

Cavity-Enhanced Quantum-Cascade Laser-Based Instrument for Trace gas Measurements

NASA Astrophysics Data System (ADS)

Provencal, R.; Gupta, M.; Owano, T.; Baer, D.; Ricci, K.; O'Keefe, A.

2005-12-01

An autonomous instrument based on Off-Axis Integrated Cavity Output Spectroscopy has been successfully deployed for measurements of CO in the troposphere and tropopause onboard a NASA DC-8 aircraft. The instrument consists of a measurement cell comprised of two high reflectivity mirrors, a continuous-wave quantum-cascade laser, gas sampling system, control and data acquisition electronics, and data analysis software. The instrument reports CO mixing ratio at a 1-Hz rate based on measured absorption, gas temperature and pressure using Beer's Law. During several flights in May-June 2004 and January 2005 that reached altitudes of 41000 ft, the instrument recorded CO values with a precision of 0.2 ppbv (1-s averaging time). Despite moderate turbulence and measurements of particulate-laden airflows, the instrument operated consistently and did not require any maintenance, mirror cleaning, or optical realignment during the flights. We will also present recent development efforts to extend the instrument's capabilities for the measurements of CH4, N2O and CO in real time.

Image defects from surface and alignment errors in grazing incidence telescopes

NASA Technical Reports Server (NTRS)

Saha, Timo T.

1989-01-01

The rigid body motions and low frequency surface errors of grazing incidence Wolter telescopes are studied. The analysis is based on surface error descriptors proposed by Paul Glenn. In his analysis, the alignment and surface errors are expressed in terms of Legendre-Fourier polynomials. Individual terms in the expression correspond to rigid body motions (decenter and tilt) and low spatial frequency surface errors of mirrors. With the help of the Legendre-Fourier polynomials and the geometry of grazing incidence telescopes, exact and approximated first order equations are derived in this paper for the components of the ray intercepts at the image plane. These equations are then used to calculate the sensitivities of Wolter type I and II telescopes for the rigid body motions and surface deformations. The rms spot diameters calculated from this theory and OSAC ray tracing code agree very well. This theory also provides a tool to predict how rigid body motions and surface errors of the mirrors compensate each other.

Recent Doppler Backscattering results from EAST tokamak

NASA Astrophysics Data System (ADS)

Zhou, Chu; Liu, Adi; Zhang, Xiaohui; Hu, Jianqiang; Wang, Mingyuan; Yu, Changxuan; Liu, Wandong; Li, Hong; Lan, Tao; Sun, Xuan; Xie, Jinlin; Ding, Weixing; CAS Key Laboratory of Geospace Environment, University of Science and Technology of China Team; Department of Physics and Astronomy, University of California at Los Angeles Collaboration

2013-10-01

A Doppler reflectometer system has recently been installed in the EAST tokamak. It includes two separated systems, one for Q-band and the other for V-band. The optical system consists of a fixed flat mirror and a steerable parabolic mirror, which enabling the measurement of perpendicular wave number in the range of 4-22/cm, with the wave number resolution around 2/cm, while the radial location can cover the whole minor radius for L mode and the whole pedestal for H mode on EAST. A 2D Gaussion Ray tracing code is used to calculate the scattering location, the perpendicular wave number and the resolution. In EAST last experimental campaign the Doppler shifted signals have been obtained and the radial profiles of the perpendicular propagation velocity during L-mode and H-mode are calculated. The Er evolution during L-H and H-L transition have also been measured. The two separated systems are also used as a poloidal coherent system together to study the GAM in EAST tokamak.

Development of a high-speed nanoprofiler using normal vector tracing

NASA Astrophysics Data System (ADS)

Kitayama, T.; Matsumura, H.; Usuki, K.; Kojima, T.; Uchikoshi, J.; Higashi, Y.; Endo, K.

2012-09-01

A new high-speed nanoprofiler was developed in this study. This profiler measures normal vectors and their coordinates on the surface of a specimen. Each normal vector and coordinate is determined by making the incident light path and the reflected light path coincident using 5-axis controlled stages. This is ensured by output signal of quadrant photo diode (QPD). From the acquired normal vectors and their coordinates, the three-dimensional shape is calculated by a reconstruction algorithm based on least-squares. In this study, a concave spherical mirror with a 400 mm radius of curvature was measured. As a result, a peak of 30 nm PV was observed at the center of the mirror. Measurement repeatability was 1 nm. In addition, cross-comparison with a Fizeau interferometer was implemented and the results were consistent within 10 nm. In particular, the high spatial frequency profile was highly consistent, and any differences were considered to be caused by systematic errors.

The penta-prism LTP: A long-trace-profiler with stationary optical head and moving penta prism (abstract)

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

Qian, S.; Jark, W.; Takacs, P.Z.

1995-02-01

Metrology requirements for optical components for third generation synchrotron sources are taxing the state-of-the-art in manufacturing technology. We have investigated a number of effect sources in a commercial figure measurement instrument, the Long Trace Profiler II (LTP II), and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, the stability of the optical system is greatly improved, and the remaining error signals can be corrected by a simple referencemore » beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.« less

Design and analysis of optical systems for the Stanford/MSFC Multi-Spectral Solar Telescope Array

NASA Astrophysics Data System (ADS)

Hadaway, James B.; Johnson, R. Barry; Hoover, Richard B.; Lindblom, Joakim F.; Walker, Arthur B. C., Jr.

1989-07-01

This paper reports on the design and the theoretical ray trace analysis of the optical systems which will comprise the primary imaging components for the Stanford/MSFC Multi-Spectral Solar Telescope Array (MSSTA). This instrument is being developed for ultra-high resolution investigations of the sun from a sounding rocket. Doubly reflecting systems of sphere-sphere, ellipsoid-sphere (Dall-Kirkham), paraboloid-hyperboloid (Cassegrain), and hyperboloid-hyperboloid (Ritchey-Chretien) configurations were analyzed. For these mirror systems, ray trace analysis was performed and through-focus spot diagrams, point spread function plots, and geometrical and diffraction MTFs were generated. The results of these studies are presented along with the parameters of the Ritchey-Chretien optical system selected for the MSSTA flight. The payload, which incorporates seven of these Ritchey-Chretien systems, is now being prepared for launch in late September 1989.

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

PubMed

Carvalho, Lina; Figueira, Paula; Monteiro, Rui; Reis, Ana Teresa; Almeida, Joana; Catry, Teresa; Lourenço, Pedro Miguel; Catry, Paulo; Barbosa, Castro; Catry, Inês; Pereira, Eduarda; Granadeiro, José Pedro; Vale, Carlos

2018-04-01

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Design and analysis of optical systems for the Stanford/MSFC Multi-Spectral Solar Telescope Array

NASA Technical Reports Server (NTRS)

Hadaway, James B.; Johnson, R. Barry; Hoover, Richard B.; Lindblom, Joakim F.; Walker, Arthur B. C., Jr.

1989-01-01

This paper reports on the design and the theoretical ray trace analysis of the optical systems which will comprise the primary imaging components for the Stanford/MSFC Multi-Spectral Solar Telescope Array (MSSTA). This instrument is being developed for ultra-high resolution investigations of the sun from a sounding rocket. Doubly reflecting systems of sphere-sphere, ellipsoid-sphere (Dall-Kirkham), paraboloid-hyperboloid (Cassegrain), and hyperboloid-hyperboloid (Ritchey-Chretien) configurations were analyzed. For these mirror systems, ray trace analysis was performed and through-focus spot diagrams, point spread function plots, and geometrical and diffraction MTFs were generated. The results of these studies are presented along with the parameters of the Ritchey-Chretien optical system selected for the MSSTA flight. The payload, which incorporates seven of these Ritchey-Chretien systems, is now being prepared for launch in late September 1989.

Effects of Ethanol-Gasoline Blended Fuels on Learning and Memory

EPA Science Inventory

The potential toxicity of ethanol-gasoline blended fuels to the developing nervous system is of concern. We previously reported an absence of effect on learning and memory as seen in a trace fear conditioning task and water maze task in offspring of dams exposed prenatally to the...

Design of an imaging microscope for soft X-ray applications

NASA Astrophysics Data System (ADS)

Hoover, Richard B.; Shealy, David L.; Gabardi, David R.; Walker, Arthur B. C., Jr.; Lindblom, Joakim F.

1988-01-01

An imaging soft X-ray microscope with a spatial resolution of 0.1 micron and normal incidence multilayer optics is discussed. The microscope has a Schwarzschild configuration, which consists of two concentric spherical mirrors with radii of curvature which minimize third-order spherical aberration, coma, and astigmatism. The performance of the Stanford/MSFC Cassegrain X-ray telescope and its relevance to the present microscope are addressed. A ray tracing analysis of the optical system indicates that diffraction-limited performance can be expected for an object height of 0.2 mm.

Unified algorithm of cone optics to compute solar flux on central receiver

NASA Astrophysics Data System (ADS)

Grigoriev, Victor; Corsi, Clotilde

2017-06-01

Analytical algorithms to compute flux distribution on central receiver are considered as a faster alternative to ray tracing. They have quite too many modifications, with HFLCAL and UNIZAR being the most recognized and verified. In this work, a generalized algorithm is presented which is valid for arbitrary sun shape of radial symmetry. Heliostat mirrors can have a nonrectangular profile, and the effects of shading and blocking, strong defocusing and astigmatism can be taken into account. The algorithm is suitable for parallel computing and can benefit from hardware acceleration of polygon texturing.

Latest animal models for anti-HIV drug discovery.

PubMed

Sliva, Katja

2015-02-01

HIV research is limited by the fact that lentiviruses are highly species specific. The need for appropriate models to promote research has led to the development of many elaborate surrogate animal models. This review looks at the history of animal models for HIV research. Although natural animal lentivirus infections and chimeric viruses such as chimera between HIV and simian immunodeficiency virus and simian-tropic HIV are briefly discussed, the main focus is on small animal models, including the complex design of the 'humanized' mouse. The review also traces the historic evolution and milestones as well as depicting current models and future prospects for HIV research. HIV research is a complex and challenging task that is highly manpower-, money- and time-consuming. Besides factors such as hypervariability and latency, the lack of appropriate animal models that exhibit and recapitulate the entire infectious process of HIV, is one of the reasons behind the failure to eliminate the lentivirus from the human population. This obstacle has led to the exploitation and further development of many sophisticated surrogate animal models for HIV research. While there is no animal model that perfectly mirrors and mimics HIV infections in humans, there are a variety of host species and viruses that complement each other. Combining the insights from each model, and critically comparing the results obtained with data from human clinical trials should help expand our understanding of HIV pathogenesis and drive future drug development.

Quantifying excessive mirror overflow in children with attention-deficit/hyperactivity disorder

PubMed Central

MacNeil, L.K.; Xavier, P.; Garvey, M.A.; Gilbert, D.L.; Ranta, M.E.; Denckla, M.B.

2011-01-01

Objectives: Qualitative observations have revealed that children with attention-deficit/hyperactivity disorder (ADHD) show increased overflow movements, a motor sign thought to reflect impaired inhibitory control. The goal of this study was to develop and implement methods for quantifying excessive mirror overflow movements in children with ADHD. Methods: Fifty right-handed children aged 8.2–13.3 years, 25 with ADHD (12 girls) and 25 typically developing (TD) control children (10 girls), performed a sequential finger-tapping task, completing both left-handed (LHFS) and right-handed finger sequencing (RHFS). Phasic overflow of the index and ring fingers was assessed in 34 children with video recording, and total overflow in 48 children was measured by calculating the total angular displacement of the index and ring fingers with electrogoniometer recordings. Results: Phasic overflow and total overflow across both hands were greater in children with ADHD than in TD children, particularly during LHFS. Separate gender analyses revealed that boys, but not girls, with ADHD showed significantly more total phasic overflow and total overflow than did their gender-matched control children. Conclusions: The quantitative overflow measures used in this study support past qualitative findings that motor overflow persists to a greater degree in children with ADHD than in age-matched TD peers. The quantitative findings further suggest that persistence of mirror overflow is more prominent during task execution of the nondominant hand and reveal gender-based differences in developmental neural systems critical to motor control. These quantitative measures will assist future physiologic investigation of the brain basis of motor control in ADHD. PMID:21321336

Training and subjective workload in a category search task

NASA Technical Reports Server (NTRS)

Vidulich, Michael A.; Pandit, Parimal

1986-01-01

This study examined automaticity as a means by which training influences mental workload. Two groups were trained in a category search task. One group received a training paradigm designed to promote the development of automaticity; the other group received a training paradigm designed to prohibit it. Resultant performance data showed the expected improvement as a result of the development of automaticity. Subjective workload assessments mirrored the performance results in most respects. The results supported the position that subjective mental workload assessments may be sensitive to the effect of training when it produces a lower level of cognitive load.

The x ray reflectivity of the AXAF VETA-I optics

NASA Technical Reports Server (NTRS)

Kellogg, Edwin M.; Chartas, G.; Graessle, D.; Hughes, John P.; Vanspeybroeck, Leon; Zhao, Ping; Weisskopf, M. C.; Elsner, R. F.; Odell, S. L.

1992-01-01

The x-ray reflectivity of the VETA-I optic, the outermost shell of the AXAF x-ray telescope, with a bare Zerodur surface, is measured and compared with theoretical predictions. Measurements made at energies of 0.28, 0.9, 1.5, 2.1, and 2.3 keV are compared with predictions based on ray trace calculations. The data were obtained at the x-ray calibrations facility at Marshall Space Flight Center with an electron impact x-ray source located 528 m from the grazing incidence mirror. The source used photoelectric absorption filters to eliminate bremsstrahlung continuum. The mirror has a diameter of 1.2 m and a focal length of 10 m. The incident and reflected x-ray flux are detected using two proportional counters, one located in the incident beam of x-rays at the entrance aperture of the VETA-I, and the other in the focal plane behind an aperture of variable size. Results on the variation of the reflectivity with energy as well as the absolute value of the reflectivity are presented. We also present a synchrotron reflectivity measurement with high energy resolution over the range 0.26 to 1.8 keV on a flat Zerodur sample, done at NSLS. We present evidence for contamination of the flat by a thin layer of carbon on the surface, and the possibility of alteration of the surface composition of the VETA-I mirror perhaps by the polishing technique. The overall agreement between the measured and calculated effective area of VETA-I is between 2.6 percent and 10 percent, depending on which model for the surface composition is adopted. Measurements at individual energies deviate from the best-fitting calculation to 0.3 to 0.8 percent, averaging 0.6 percent at energies below the high energy cutoff of the mirror reflectivity, and are as high as 20.7 percent at the cutoff. We also discuss the approach to the final preflight calibration of the full AXAF flight mirror.

Hyperbrain features of team mental models within a juggling paradigm: a proof of concept

PubMed Central

Filho, Edson; Tamburro, Gabriella; Schinaia, Lorenzo; Chatel-Goldman, Jonas; di Fronso, Selenia; Robazza, Claudio

2016-01-01

Background Research on cooperative behavior and the social brain exists, but little research has focused on real-time motor cooperative behavior and its neural correlates. In this proof of concept study, we explored the conceptual notion of shared and complementary mental models through EEG mapping of two brains performing a real-world interactive motor task of increasing difficulty. We used the recently introduced participative “juggling paradigm,” and collected neuro-physiological and psycho-social data. We were interested in analyzing the between-brains coupling during a dyadic juggling task, and in exploring the relationship between the motor task execution, the jugglers’skill level and the task difficulty. We also investigated how this relationship could be mirrored in the coupled functional organization of the interacting brains. Methods To capture the neural schemas underlying the notion of shared and complementary mental models, we examined the functional connectivity patterns and hyperbrain features of a juggling dyad involved in cooperative motor tasks of increasing difficulty. Jugglers’ cortical activity was measured using two synchronized 32-channel EEG systems during dyadic juggling performed with 3, 4, 5 and 6 balls. Individual and hyperbrain functional connections were quantified through coherence maps calculated across all electrode pairs in the theta and alpha bands (4–8 and 8–12 Hz). Graph metrics were used to typify the global topology and efficiency of the functional networks for the four difficulty levels in the theta and alpha bands. Results Results indicated that, as task difficulty increased, the cortical functional organization of the more skilled juggler became progressively more segregated in both frequency bands, with a small-world organization in the theta band during easier tasks, indicative of a flow-like state in line with the neural efficiency hypothesis. Conversely, more integrated functional patterns were observed for the less skilled juggler in both frequency bands, possibly related to cognitive overload due to the difficulty of the task at hand (reinvestment hypothesis). At the hyperbrain level, a segregated functional organization involving areas of the visuo-attentional networks of both jugglers was observed in both frequency bands and for the easier task only. Discussion These results suggest that cooperative juggling is supported by integrated activity of specialized cortical areas from both brains only during easier tasks, whereas it relies on individual skills, mirrored in uncorrelated individual brain activations, during more difficult tasks. These findings suggest that task difficulty and jugglers’ personal skills may influence the features of the hyperbrain network in its shared/integrative and complementary/segregative tendencies. PMID:27688968

Human Cognition and Information Display in C3I System Tasks.

DTIC Science & Technology

1988-12-01

goes without saying that rule-based tasks are the easiest to automate, but for reasons discussed earlier, they still merit our attention . Moreover...selective attention task. Since selective attention must operate after memory retrieval, it is only when different responses are elicited that the...stimuli that is processed by impairing the memory traces of signals that originally attract less attention . Although the research reviewed above gives

Test-Retest Reliability of Measures Commonly Used to Measure Striatal Dysfunction across Multiple Testing Sessions: A Longitudinal Study.

PubMed

Palmer, Clare E; Langbehn, Douglas; Tabrizi, Sarah J; Papoutsi, Marina

2017-01-01

Cognitive impairment is common amongst many neurodegenerative movement disorders such as Huntington's disease (HD) and Parkinson's disease (PD) across multiple domains. There are many tasks available to assess different aspects of this dysfunction, however, it is imperative that these show high test-retest reliability if they are to be used to track disease progression or response to treatment in patient populations. Moreover, in order to ensure effects of practice across testing sessions are not misconstrued as clinical improvement in clinical trials, tasks which are particularly vulnerable to practice effects need to be highlighted. In this study we evaluated test-retest reliability in mean performance across three testing sessions of four tasks that are commonly used to measure cognitive dysfunction associated with striatal impairment: a combined Simon Stop-Signal Task; a modified emotion recognition task; a circle tracing task; and the trail making task. Practice effects were seen between sessions 1 and 2 across all tasks for the majority of dependent variables, particularly reaction time variables; some, but not all, diminished in the third session. Good test-retest reliability across all sessions was seen for the emotion recognition, circle tracing, and trail making test. The Simon interference effect and stop-signal reaction time (SSRT) from the combined-Simon-Stop-Signal task showed moderate test-retest reliability, however, the combined SSRT interference effect showed poor test-retest reliability. Our results emphasize the need to use control groups when tracking clinical progression or use pre-baseline training on tasks susceptible to practice effects.

Differential effects of acute cortisol administration on deep and shallow episodic memory traces: a study on healthy males.

PubMed

Cioncoloni, David; Galli, Giulia; Mazzocchio, Riccardo; Feurra, Matteo; Giovannelli, Fabio; Santarnecchi, Emiliano; Bonifazi, Marco; Rossi, Alessandro; Rossi, Simone

2014-10-01

We aimed at investigating rapid effects of plasma cortisol elevations on the episodic memory phase of encoding or retrieval, and on the strength of the memory trace. Participants were asked either to select a word containing the letter "e" (shallow encoding task) or to judge if a word referred to a living entity (deep encoding task). We intravenously administered a bolus of 20mg of cortisol either 5 min before encoding or 5 min before retrieval, in a between-subjects design. The study included only male participants tested in the late afternoon, and neutral words as stimuli. When cortisol administration occurred prior to retrieval, a main effect of group emerged. Recognition accuracy was higher for individuals who received cortisol compared to placebo. The higher discrimination accuracy for the cortisol group was significant for words encoded during deep but not shallow task. Cortisol administration before encoding did not affect subsequent retrieval performance (either for deep or shallow stimuli) despite a facilitatory trend. Because genomic mechanisms take some time to develop, such a mechanism cannot apply to our findings where the memory task was performed shortly after the enhancement of glucocorticoid levels. Therefore, glucocorticoids, through non-genomic fast effects, determine an enhancement in episodic memory if administered immediately prior to retrieval. This effect is more evident if the memory trace is laid down through deep encoding operations involving the recruitment of specific neural networks. Copyright © 2014 Elsevier Inc. All rights reserved.

The Role of Task Understanding on Younger and Older Adults' Performance.

PubMed

Frank, David J; Touron, Dayna R

2016-12-16

Age-related performance decrements have been linked to inferior strategic choices. Strategy selection models argue that accurate task representations are necessary for choosing appropriate strategies. But no studies to date have compared task representations in younger and older adults. Metacognition research suggests age-related deficits in updating and utilizing strategy knowledge, but other research suggests age-related sparing when information can be consolidated into a coherent mental model. Study 1 validated the use of concept mapping as a tool for measuring task representation accuracy. Study 2 measured task representations before and after a complex strategic task to test for age-related decrements in task representation formation and updating. Task representation accuracy and task performance were equivalent across age groups. Better task representations were related to better performance. However, task representation scores remained fairly stable over the task with minimal evidence of updating. Our findings mirror those in the mental model literature suggesting age-related sparing of strategy use when information can be integrated into a coherent mental model. Future research should manipulate the presence of a unifying context to better evaluate this hypothesis. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Dynamic Geometry Software and Tracing Tangents in the Context of the Mean Value Theorem: Technique and Theory Production

ERIC Educational Resources Information Center

Martínez-Hernández, Cesar; Ulloa-Azpeitia, Ricardo

2017-01-01

Based on the theoretical elements of the instrumental approach to tool use known as Task-Technique-Theory (Artigue, 2002), this paper analyses and discusses the performance of graduate students enrolled in a Teacher Training program. The latter performance relates to tracing tangent lines to the curve of a quadratic function in Dynamic Geometry…

Somatic and movement inductions phantom limb in non-amputees

NASA Astrophysics Data System (ADS)

Casas, D. M.; Gentiletti, G. G.; Braidot, A. A.

2016-04-01

The illusion of the mirror box is a tool for phantom limb pain treatment; this article proposes the induction of phantom limb syndrome on non-amputees upper limb, with a neurological trick of the mirror box. With two study situations: a) Somatic Induction is a test of the literature reports qualitatively, and novel proposal b) Motor Induction, which is an objective report by recording surface EEG. There are 3 cases proposed for Motor illusion, for which grasped movement is used: 1) Control: movement is made, 2) illusion: the mirror box is used, and 3) Imagination: no movement is executed; the subject only imagines its execution. Three different tasks are registered for each one of them (left hand, right hand, and both of them). In 64% of the subjects for somatic experience, a clear response to the illusion was observed. In the experience of motor illusion, cortical activation is detected in both hemispheres of the primary motor cortex during the illusion, where the hidden hand remains motionless. These preliminary findings in phantom limb on non-amputees can be a tool for neuro-rehabilitation and neuro-prosthesis control training.

Tilt angle measurement with a Gaussian-shaped laser beam tracking

NASA Astrophysics Data System (ADS)

Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr; Lazar, Josef; Číp, Ondrej

2014-05-01

We have addressed the challenge to carry out the angular tilt stabilization of a laser guiding mirror which is intended to route a laser beam with a high energy density. Such an application requires good angular accuracy as well as large operating range, long term stability and absolute positioning. We have designed an instrument for such a high precision angular tilt measurement based on a triangulation method where a laser beam with Gaussian profile is reflected off the stabilized mirror and detected by an image sensor. As the angular deflection of the mirror causes a change of the beam spot position, the principal task is to measure the position on the image chip surface. We have employed a numerical analysis of the Gaussian intensity pattern which uses the nonlinear regression algorithm. The feasibility and performance of the method were tested by numeric modeling as well as experimentally. The experimental results indicate that the assembled instrument achieves a measurement error of 0.13 microradian in the range +/-0.65 degrees over the period of one hour. This corresponds to the dynamic range of 1:170 000.

Enhanced optical alignment of a digital micro mirror device through Bayesian adaptive exploration

NASA Astrophysics Data System (ADS)

Wynne, Kevin B.; Knuth, Kevin H.; Petruccelli, Jonathan

2017-12-01

As the use of Digital Micro Mirror Devices (DMDs) becomes more prevalent in optics research, the ability to precisely locate the Fourier "footprint" of an image beam at the Fourier plane becomes a pressing need. In this approach, Bayesian adaptive exploration techniques were employed to characterize the size and position of the beam on a DMD located at the Fourier plane. It couples a Bayesian inference engine with an inquiry engine to implement the search. The inquiry engine explores the DMD by engaging mirrors and recording light intensity values based on the maximization of the expected information gain. Using the data collected from this exploration, the Bayesian inference engine updates the posterior probability describing the beam's characteristics. The process is iterated until the beam is located to within the desired precision. This methodology not only locates the center and radius of the beam with remarkable precision but accomplishes the task in far less time than a brute force search. The employed approach has applications to system alignment for both Fourier processing and coded aperture design.

Asian Lifelong Learning in the Context of a Global Knowledge Economy: A Task Re-Visited

ERIC Educational Resources Information Center

Han, Soonghee

2007-01-01

This article revisits and reinterprets my previous paper. It is a snapshot of the lifelong learning system building in selected Asian countries, reflected in the mirror of the Asian Financial Crisis in the 1997s and the aftermath of that event. I reconsidered the arguments (1) the economic recession had delivered a global dimension of lifelong…

Object words modulate the activity of the mirror neuron system during action imitation.

PubMed

Wu, Haiyan; Tang, Honghong; Ge, Yue; Yang, Suyong; Mai, Xiaoqin; Luo, Yue-Jia; Liu, Chao

2017-11-01

Although research has demonstrated that the mirror neuron system (MNS) plays a crucial role in both action imitation and action-related semantic processing, whether action-related words can inversely modulate the MNS activity remains unclear. Here, three types of task-irrelevant words (body parts, verbs, and manufactured objects) were presented to examine the modulation effect of these words on the MNS activity during action observation and imitation. Twenty-two participants were recruited for the fMRI scanning and remaining data from 19 subjects were reported here. Brain activity results showed that word types elicited different modulation effects over nodes of the MNS (i.e., the right inferior frontal gyrus, premotor cortex, inferior parietal lobule, and STS), especially during the imitation stage. Compared with other word conditions, action imitation following manufactured objects words induced stronger activation in these brain regions during the imitation stage. These results were consistent in both task-dependent and -independent ROI analysis. Our findings thus provide evidence for the unique effect of object words on the MNS during imitation of action, which may also confirm the key role of goal inference in action imitation.

Effects of a Fragmented View of One’s Partner on Interpersonal Coordination in Dance

PubMed Central

Brown, Derrick D.; Meulenbroek, Ruud G. J.

2016-01-01

In this study we investigated the effects of a mirror-mediated, partial view of one’s dance partner on interpersonal coordination in dance duets. Fourteen participant pairs (dyads) were asked to perform a reflectionally-symmetric eight-segment dance-relevant arm movement sequence in two visual conditions: with one dancer facing the mirror and providing a partial view on the dance partner, or both dancers facing back to back with, for both dancers, no view on one’s partner. During an eight-count beat-preparation phase, the task was paced via a metronome at three TEMPI; 1.6, 1.9, and 2.3 Hz, which was subsequently removed after which the movement sequence continued in silence. Interpersonal coordination was assessed using two tri-axial wireless accelerometers, one fixed to each dancer, that allowed the off-line kinematic analyses of dyad correlation, mean relative phase and mean standard deviation of relative phase of the up–down movements of (one of) the hands of the two dancers. In addition, two independent raters estimated the realized movement frequencies and percentage of the trial duration that the dancers moved in sync. Repeated measure ANOVAs revealed systematic effects of tempo on the performance measures, a positive effect of the use of the mirror on the coordination of the dancers’ movements but no facilitating effect of the mirror on the dancers’ synchronization. Overall, the results support the contention that when dancing to an internalized rhythmic beat the use of a mirror provides an ecological means to stabilize interpersonal coordination in dance duets without an effect on synchronization. PMID:27199847

What counts? Visual and verbal cues interact to influence what is considered a countable thing.

PubMed

Chesney, Dana L; Gelman, Rochel

2015-07-01

Many famous paintings illustrate variations in what we here dub "referential depth." For example, paintings often include not only portrayals of uniquely referenced items, but also reflections of those items in mirrors or other polished surfaces. If a painting includes both a dancer and that dancer's reflection in a mirror, are there one or two dancers in the painting? Although there are two images of a dancer, both images reference the exact same dancer. Consequently, counting both may seem to violate the constraint against double counting (Gelman & Gallistel, 1978). This illustrates that determining which things "count" in a given context may not be straightforward. Here we used counting tasks paired with illustrations that manipulated referential depth to investigate the conceptual, perceptual, and language variables that may influence whether a "thing" is a "countable thing." Across four experiments, 316 participants counted items in displays that included both foreground items and items placed inside mirrors, picture frames, and windows. Referential depth and frame boundaries both influenced counting: For one thing, participants were more likely to count items contained by windows than by picture frames or mirrors. Moreover, items in mirrors were rarely counted unless they were interpreted as reflections of items "off screen." Also, the items contained inside windows were sometimes (~10% of trials) excluded from the counts, when counting them would require crossing frame boundaries. We concluded that conceptual and perceptual contexts both influence people's decisions about the physical boundaries of the to-be-counted set and which items within these boundaries are countable.

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

Langridge, Justin M.; Shillings, Alexander J. L.; Jones, Roderic L.

A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modesmore » of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO{sub 2} (versus a laser broadband cavity ringdown spectrometer) and for H{sub 2}O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+{delta} absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO{sub 3} as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1{sigma} detection limit of 0.25 pptv for a 10 s acquisition time, which improves with further signal averaging to 0.09 pptv in 400 s. Finally, an example of the instrument's performance under field work conditions is presented, in this case of measurements of the sum of NO{sub 3}+N{sub 2}O{sub 5} concentrations in the marine boundary layer acquired during the Reactive Halogens in the Marine Boundary Layer field campaign.« less

[Genotype-dependent mice behavior in cognitive tasks. Effect of noopept].

PubMed

Bel'nik, A P; Ostrovskaia, R U; Poletaeva, I I

2007-01-01

The interstrain differences in performance of C57BL/6J, BALB/c and DBA/2J male mice in two cognitive tasks were found. Mice C57BL/6J showed good learning ability and preservation of memory traces tested 10 days after performance in a simplified version of Morris water maze. Mice BALB/c learned the task but, virtually, no long-term memory traces were revealed, whereas DBA/2J demonstrated poor learning. The effect of nootropic drug Noopept (GVS-111, N-phenil-acetyl-L-prolylglycin ethyl ether) was shown to be genotype-dependent. Its administration (0.5 mg/kg i.p., 15 min before learning) improved the long-term memory in Morris test in BALB/c mice but failed to produce any improvement in C57BL/6J. The ability of mice for extrapolation of the direction of stimulus movement differently changed after Noopept injections: the proportion of correct task solutions increased in C57BL/6J and BALB/c mice, whereas the performance of DBA/2J did not change.

Switching Attention Within Working Memory is Reflected in the P3a Component of the Human Event-Related Brain Potential

PubMed Central

Berti, Stefan

2016-01-01

The flexible access to information in working memory is crucial for adaptive behavior. It is assumed that this is realized by switching the focus of attention within working memory. Switching of attention is mirrored in the P3a component of the human event-related brain potential (ERP) and it has been argued that the processes reflected by the P3a are also relevant for selecting information within working memory. The aim of the present study was to further evaluate whether the P3a mirrors genuine switching of attention within working memory by applying an object switching task: Participants updated a memory list of four digits either by replacing one item with another digit or by processing the stored digit. ERPs were computed separately for two types of trials: (1) trials in which an object was repeated and (2) trials in which a switch to a new object was required in order to perform the task. Object-switch trials showed increased response times compared with repetition trials in both task conditions. In addition, switching costs were increased in the processing compared with the replacement condition. Pronounced P3a’s were obtained in switching trials but there were no difference between the two updating tasks (replacement or processing). These results were qualified by the finding that the magnitude of the visual location shift also affects the ERPs in the P3a time window. Taken together, the present pattern of results suggest that the P3a reflects an initial process of selecting information in working memory but not the memory updating itself. PMID:26779009

Visual information processing in the lion-tailed macaque (Macaca silenus): mental rotation or rotational invariance?

PubMed

Burmann, Britta; Dehnhardt, Guido; Mauck, Björn

2005-01-01

Mental rotation is a widely accepted concept indicating an image-like mental representation of visual information and an analogue mode of information processing in certain visuospatial tasks. In the task of discriminating between image and mirror-image of rotated figures, human reaction times increase with the angular disparity between the figures. In animals, tests of this kind yield inconsistent results. Pigeons were found to use a time-independent rotational invariance, possibly indicating a non-analogue information processing system that evolved in response to the horizontal plane of reference birds perceive during flight. Despite similar ecological demands concerning the visual reference plane, a sea lion was found to use mental rotation in similar tasks, but its processing speed while rotating three-dimensional stimuli seemed to depend on the axis of rotation in a different way than found for humans in similar tasks. If ecological demands influence the way information processing systems evolve, hominids might have secondarily lost the ability of rotational invariance while retreating from arboreal living and evolving an upright gait in which the vertical reference plane is more important. We therefore conducted mental rotation experiments with an arboreal living primate species, the lion-tailed macaque. Performing a two-alternative matching-to-sample procedure, the animal had to decide between rotated figures representing image and mirror-image of a previously shown upright sample. Although non-rotated stimuli were recognized faster than rotated ones, the animal's mean reaction times did not clearly increase with the angle of rotation. These results are inconsistent with the mental rotation concept but also cannot be explained assuming a mere rotational invariance. Our study thus seems to support the idea of information processing systems evolving gradually in response to specific ecological demands.

It's how you get there: walking down a virtual alley activates premotor and parietal areas.

PubMed

Wagner, Johanna; Solis-Escalante, Teodoro; Scherer, Reinhold; Neuper, Christa; Müller-Putz, Gernot

2014-01-01

Voluntary drive is crucial for motor learning, therefore we are interested in the role that motor planning plays in gait movements. In this study we examined the impact of an interactive Virtual Environment (VE) feedback task on the EEG patterns during robot assisted walking. We compared walking in the VE modality to two control conditions: walking with a visual attention paradigm, in which visual stimuli were unrelated to the motor task; and walking with mirror feedback, in which participants observed their own movements. Eleven healthy participants were considered. Application of independent component analysis to the EEG revealed three independent component clusters in premotor and parietal areas showing increased activity during walking with the adaptive VE training paradigm compared to the control conditions. During the interactive VE walking task spectral power in frequency ranges 8-12, 15-20, and 23-40 Hz was significantly (p ≤ 0.05) decreased. This power decrease is interpreted as a correlate of an active cortical area. Furthermore activity in the premotor cortex revealed gait cycle related modulations significantly different (p ≤ 0.05) from baseline in the frequency range 23-40 Hz during walking. These modulations were significantly (p ≤ 0.05) reduced depending on gait cycle phases in the interactive VE walking task compared to the control conditions. We demonstrate that premotor and parietal areas show increased activity during walking with the adaptive VE training paradigm, when compared to walking with mirror- and movement unrelated feedback. Previous research has related a premotor-parietal network to motor planning and motor intention. We argue that movement related interactive feedback enhances motor planning and motor intention. We hypothesize that this might improve gait recovery during rehabilitation.

Time and number of displays impact critical signal detection in fetal heart rate tracings.

PubMed

Anderson, Brittany L; Scerbo, Mark W; Belfore, Lee A; Abuhamad, Alfred Z

2011-06-01

Interest in centralized monitoring in labor and delivery units is growing because it affords the opportunity to monitor multiple patients simultaneously. However, a long history of research on sustained attention reveals these types of monitoring tasks can be problematic. The goal of the present experiment was to examine the ability of individuals to detect critical signals in fetal heart rate (FHR) tracings in one or more displays over an extended period of time. Seventy-two participants monitored one, two, or four computer-simulated FHR tracings on a computer display for the appearance of late decelerations over a 48-minute vigil. Measures of subjective stress and workload were also obtained before and after the vigil. The results showed that detection accuracy decreased over time and also declined as the number of displays increased. The subjective reports indicated that participants found the task to be stressful and mentally demanding, effortful, and frustrating. The results suggest that centralized monitoring that allows many patients to be monitored simultaneously may impose a detrimental attentional burden on the observer. Furthermore, this seemingly benign task may impose an additional source of stress and mental workload above what is commonly found in labor and delivery units. © Thieme Medical Publishers.

Performance of a double tilted-Rowland-spectrometer on Arcus

NASA Astrophysics Data System (ADS)

Günther, Hans M.; Cheimets, P. N.; Heilmann, R. K.; Smith, R. K.

2017-08-01

Spectroscopy of soft X-rays is an extremely powerful tool to understand the physics of the hot plasma in the universe but in many cases, such as kinematic properties of stellar emission lines or weak absorption features, we have reached the limits of current instrumentation. Critical-angle transmission (CAT) gratings blaze the dispersed spectra into high orders and also offer a high throughput. We present detailed ray-traces for the Arcus mission, which promises an effective area > 0.5 m2 and resolving power > 2500 in the soft X-rays. The mirror consists of Athena-like silicon pore optics (SPOs) arranged in four petals. Each petal spans an azimuth of about 30 degrees and thus offers a point-spread function that is significantly narrower in one dimension than a full mirror would provide. The four channels are split into two pairs, where each pair has its own optical axis. For each pair, CAT gratings are arranged on a tilted Rowland torus and the two separate tori are positioned to overlap in such a way that the dispersed spectra from both pairs can be imaged onto a common set of CCD detectors, while at the same time keeping the requirement of the spectroscopic focus. Our ray-traces show that a set of 16 CCDs is sufficient to cover both zeroths orders and over 90% of the dispersed signal. We study the impact of misalignment, finite size of components, and spacecraft jitter on the spectral resolution and effective area and prove that the design achieves R > 4000 even in the presence of these non-ideal effects.

Design, optimization and characterization of the light concentrators of the single-mirror small size telescopes of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Basili, A.; Boccone, V.; Cadoux, F.; Christov, A.; della Volpe, D.; Montaruli, T.; Płatos, Ł.; Rameez, M.

2015-01-01

The focal-plane cameras of γ -ray telescopes frequently use light concentrators in front of the light sensors. The purpose of these concentrators is to increase the effective area of the camera as well as to reduce the stray light coming at large incident angles. These light concentrators are usually based on the Winston cone design. In this contribution we present the design of a hexagonal hollow light concentrator with a lateral profile optimized using a cubic Bézier function to achieve a higher collection efficiency in the angular region of interest. The design presented here is optimized for a Davies-Cotton telescope with a primary mirror of about 4 m in diameter and a focal length of 5.6 m. The described concentrators are part of an innovative camera made up of silicon-photomultiplier sensors, although a similar approach can be used for other sizes of single-mirror telescopes with different camera sensors, including photomultipliers. The challenge of our approach is to achieve a cost-effective design suitable for standard industrial production of both the plastic concentrator substrate and the reflective coating. At the same time we maximize the optical performance. In this paper we also describe the optical set-up to measure the absolute collection efficiency of the light concentrators and demonstrate our good understanding of the measured data using a professional ray-tracing simulation.

A VUV detection system for the direct photonic identification of the first excited isomeric state of 229Th

NASA Astrophysics Data System (ADS)

Seiferle, Benedict; von der Wense, Lars; Laatiaoui, Mustapha; Thirolf, Peter G.

2016-03-01

With an expected energy of 7.6(5) eV, 229Th possesses the lowest excited nuclear state in the landscape of all presently known nuclei. The energy corresponds to a wavelength of about 160 nm and would conceptually allow for an optical laser excitation of a nuclear transition. We report on a VUV optical detection system that was designed for the direct detection of the isomeric ground-state transition of 229Th. 229(m)Th ions originating from a 233U α-recoil source are collected on a micro electrode that is placed in the focus of an annular parabolic mirror. The latter is used to parallelize the UV fluorescence that may emerge from the isomeric ground-state transition of 229Th. The parallelized light is then focused by a second annular parabolic mirror onto a CsI-coated position-sensitive MCP detector behind the mirror exit. To achieve a high signal-to-background ratio, a small spot size on the MCP detector needs to be achieved. Besides extensive ray-tracing simulations of the optical setup, we present a procedure for its alignment, as well as test measurements using a D2 lamp, where a focal-spot size of ≈100 μm has been achieved. Assuming a purely photonic decay, a signal-to-background ratio of ≈7000:1 could be achieved.

Negatively-chirped laser enables nonlinear excitation and nanoprocessing with sub-20-fs pulses

NASA Astrophysics Data System (ADS)

Uchugonova, A.; Müller, J.; Bückle, R.; Tempea, G.; Isemann, A.; Stingl, A.; König, K.

2008-02-01

It has long been considered that the advantages emerging from employing chirp pre-compensation in nonlinear microscopy were overweighed by the complexity of prism- or grating-based compressors. These concerns were refuted with the advent of dispersive-mirrors-based compressors that are compact, user-friendly and sufficiently accurate to support sub-20-fs pulse delivery. Recent advances in the design of dispersive multilayer mirrors resulted in improved bandwidth (covering now as much as half of the gain bandwidth of Ti:Sapphire) and increased dispersion per bounce (one reflection off a state-of-the-art dispersive mirror pre-compensates the dispersion corresponding to >10mm of glass). The compressor built with these mirrors is sufficiently compact to be integrated in the housing of a sub-12-fs Ti:Sapphire oscillator. A complete scanning nonlinear microscope (FemtOgene, JenLab GmbH) equipped with highly-dispersive, large-NA objectives (Zeiss EC Plan-Neofluoar 40x/1.3, Plan-Neofluar 63x/1,25 Oil) was directly seeded with this negatively chirped laser. The pulse duration was measured at the focus of the objectives by inserting a scanning autocorrelator in the beam path between the laser and the microscope and recording the second order interferometric autocorrelation traces with the detector integrated in the microscope. Pulse durations <20fs were measured with both objectives. The system has been applied for two-photon imaging, transfection and optical manipulation of stem cells. Here we report on the successful transfection of human stem cells by transient optoporation of the cell membrane with a low mean power of < 7 mW and a short μs beam dwell time. Optically transfected cells were able to reproduce. The daughter cell expressed also green fluorescent proteins (GFP) indicating the successful modification of the cellular DNA.

Partially coherent X-ray wavefront propagation simulations including grazing-incidence focusing optics.

PubMed

Canestrari, Niccolo; Chubar, Oleg; Reininger, Ruben

2014-09-01

X-ray beamlines in modern synchrotron radiation sources make extensive use of grazing-incidence reflective optics, in particular Kirkpatrick-Baez elliptical mirror systems. These systems can focus the incoming X-rays down to nanometer-scale spot sizes while maintaining relatively large acceptance apertures and high flux in the focused radiation spots. In low-emittance storage rings and in free-electron lasers such systems are used with partially or even nearly fully coherent X-ray beams and often target diffraction-limited resolution. Therefore, their accurate simulation and modeling has to be performed within the framework of wave optics. Here the implementation and benchmarking of a wave-optics method for the simulation of grazing-incidence mirrors based on the local stationary-phase approximation or, in other words, the local propagation of the radiation electric field along geometrical rays, is described. The proposed method is CPU-efficient and fully compatible with the numerical methods of Fourier optics. It has been implemented in the Synchrotron Radiation Workshop (SRW) computer code and extensively tested against the geometrical ray-tracing code SHADOW. The test simulations have been performed for cases without and with diffraction at mirror apertures, including cases where the grazing-incidence mirrors can be hardly approximated by ideal lenses. Good agreement between the SRW and SHADOW simulation results is observed in the cases without diffraction. The differences between the simulation results obtained by the two codes in diffraction-dominated cases for illumination with fully or partially coherent radiation are analyzed and interpreted. The application of the new method for the simulation of wavefront propagation through a high-resolution X-ray microspectroscopy beamline at the National Synchrotron Light Source II (Brookhaven National Laboratory, USA) is demonstrated.

Emotional task management: neural correlates of switching between affective and non-affective task-sets.

PubMed

Reeck, Crystal; Egner, Tobias

2015-08-01

Although task-switching has been investigated extensively, its interaction with emotionally salient task content remains unclear. Prioritized processing of affective stimulus content may enhance accessibility of affective task-sets and generate increased interference when switching between affective and non-affective task-sets. Previous research has demonstrated that more dominant task-sets experience greater switch costs, as they necessitate active inhibition during performance of less entrenched tasks. Extending this logic to the affective domain, the present experiment examined (a) whether affective task-sets are more dominant than non-affective ones, and (b) what neural mechanisms regulate affective task-sets, so that weaker, non-affective task-sets can be executed. While undergoing functional magnetic resonance imaging, participants categorized face stimuli according to either their gender (non-affective task) or their emotional expression (affective task). Behavioral results were consistent with the affective task dominance hypothesis: participants were slower to switch to the affective task, and cross-task interference was strongest when participants tried to switch from the affective to the non-affective task. These behavioral costs of controlling the affective task-set were mirrored in the activation of a right-lateralized frontostriatal network previously implicated in task-set updating and response inhibition. Connectivity between amygdala and right ventrolateral prefrontal cortex was especially pronounced during cross-task interference from affective features. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

[A trace methane gas sensor using mid-infrared quantum cascaded laser at 7.5 microm].

PubMed

Chen, Chen; Dang, Jing-Min; Huang, Jian-Qiang; Yang, Yue; Wang, Yi-Ding

2012-11-01

Presented is a compact instrument developed for in situ high-stable and sensitive continuous measurement of trace gases in air, with results shown for ambient methane (CH4) concentration accurate, real-time and in-situ. This instrument takes advantage of recent technology in thermoelectrically cooling (TEC) pulsed Fabry-Perot (FP) quantum cascaded laser (QCL) driving in a pulse mode operating at 7.5 microm ambient temperature to cover a fundamental spectral absorption band near v4 of CH4. A high quality Liquid Nitrogen (LN) cooled Mercury Cadmium Telluride (HgCdTe) mid-infrared (MIR) detector is used along with a total reflection coated gold ellipsoid mirror offering 20 cm single pass optical absorption in an open-path cell to achieve stability of 5.2 x 10(-3) under experimental condition of 200 micromol x mol(-1) measured ambient CH4. The instrument integrated software via time discriminating electronics technology to control QCL provides continuous quantitative trace gas measurements without calibration. The results show that the instrument can be applied to field measurements of gases of environmental concern. Additional, operator could substitute a QCL operating at a different wavelength to measure other gases.

Rapid natural scene categorization in the near absence of attention

PubMed Central

Li, Fei Fei; VanRullen, Rufin; Koch, Christof; Perona, Pietro

2002-01-01

What can we see when we do not pay attention? It is well known that we can be “blind” even to major aspects of natural scenes when we attend elsewhere. The only tasks that do not need attention appear to be carried out in the early stages of the visual system. Contrary to this common belief, we report that subjects can rapidly detect animals or vehicles in briefly presented novel natural scenes while simultaneously performing another attentionally demanding task. By comparison, they are unable to discriminate large T's from L's, or bisected two-color disks from their mirror images under the same conditions. We conclude that some visual tasks associated with “high-level” cortical areas may proceed in the near absence of attention. PMID:12077298

A comparative evaluation of in-vehicle side view displays layouts in critical lane changing situation.

PubMed

Beck, Donghyun; Lee, Minho; Park, Woojin

2017-12-01

This study conducted a driving simulator experiment to comparatively evaluate three in-vehicle side view displays layouts for camera monitor systems (CMS) and the traditional side view mirror arrangement. The three layouts placed two electronic side view displays near the traditional mirrors positions, on the dashboard at each side of the steering wheel and on the centre fascia with the two displays joined side-by-side, respectively. Twenty-two participants performed a time- and safety-critical driving task that required rapidly gaining situation awareness through the side view displays/mirrors and making a lane change to avoid collision. The dependent variables were eye-off-the-road time, response time, and, ratings of perceived workload, preference and perceived safety. Overall, the layout placing the side view displays on the dashboard at each side of the steering wheel was found to be the best. The results indicated that reducing eye gaze travel distance and maintaining compatibility were both important for the design of CMS displays layout. Practitioner Summary: A driving simulator study was conducted to comparatively evaluate three in-vehicle side view displays layouts for camera monitor systems (CMS) and the traditional side view mirror arrangement in critical lane changing situation. Reducing eye movement and maintaining compatibility were found to be both important for the ergonomics design of CMS displays layout.

Simultaneous intrinsic and extrinsic calibration of a laser deflecting tilting mirror in the projective voltage space.

PubMed

Schneider, Adrian; Pezold, Simon; Baek, Kyung-Won; Marinov, Dilyan; Cattin, Philippe C

2016-09-01

PURPOSE  : During the past five decades, laser technology emerged and is nowadays part of a great number of scientific and industrial applications. In the medical field, the integration of laser technology is on the rise and has already been widely adopted in contemporary medical applications. However, it is new to use a laser to cut bone and perform general osteotomy surgical tasks with it. In this paper, we describe a method to calibrate a laser deflecting tilting mirror and integrate it into a sophisticated laser osteotome, involving next generation robots and optical tracking. METHODS  : A mathematical model was derived, which describes a controllable deflection mirror by the general projective transformation. This makes the application of well-known camera calibration methods possible. In particular, the direct linear transformation algorithm is applied to calibrate and integrate a laser deflecting tilting mirror into the affine transformation chain of a surgical system. RESULTS  : Experiments were performed on synthetic generated calibration input, and the calibration was tested with real data. The determined target registration errors in a working distance of 150 mm for both simulated input and real data agree at the declared noise level of the applied optical 3D tracking system: The evaluation of the synthetic input showed an error of 0.4 mm, and the error with the real data was 0.3 mm.

Scheduling observational and physical practice: influence on the coding of simple motor sequences.

PubMed

Ellenbuerger, Thomas; Boutin, Arnaud; Blandin, Yannick; Shea, Charles H; Panzer, Stefan

2012-01-01

The main purpose of the present experiment was to determine the coordinate system used in the development of movement codes when observational and physical practice are scheduled across practice sessions. The task was to reproduce a 1,300-ms spatial-temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two effector (contralateral limb) transfer tests was used. The mirror effector transfer test required the same pattern of homologous muscle activation and sequence of limb joint angles as that performed or observed during practice, and the non-mirror effector transfer test required the same spatial pattern movements as that performed or observed. The test results following the first acquisition session replicated the findings of Gruetzmacher, Panzer, Blandin, and Shea (2011) . The results following the second acquisition session indicated a strong advantage for participants who received physical practice in both practice sessions or received observational practice followed by physical practice. This advantage was found on both the retention and the mirror transfer tests compared to the non-mirror transfer test. These results demonstrate that codes based in motor coordinates can be developed relatively quickly and effectively for a simple spatial-temporal movement sequence when participants are provided with physical practice or observation followed by physical practice, but physical practice followed by observational practice or observational practice alone limits the development of codes based in motor coordinates.

Telescope Innovations Improve Speed, Accuracy of Eye Surgery

NASA Technical Reports Server (NTRS)

2013-01-01

One of the main components of NASA's vision for the future of space exploration will actually have a keen eye for the past. The James Webb Space Telescope (JWST), scheduled to launch in 2018, will have spectacular sight, after it reaches orbit, one of its main goals is to observe the first galaxies that formed in the early universe. "JWST offers new capabilities in the infrared well beyond what we can see from current telescopes, either on the ground or in space. It will let us explore the early universe, extrasolar planets, and really, all branches of astrophysics," says Lee Feinberg, optical telescope element manager for the JWST at Goddard Space Flight Center. Building such a keen space telescope is an astronomic task. Because JWST will gaze over such incredible distances, it requires very large mirrors. In fact, the primary mirror will be more than two stories in diameter and consists of 18 separate segments. Each segment must be perfectly smooth, flat, and scratch-free in order to deliver a view 13 billion light years away. Construction of the 18 mirror segments involved measuring, grinding, polishing, and testing - and more measuring, grinding, polishing, and testing - and more measuring, grinding, polishing, and testing (you get the idea). One of the most time consuming steps of the mirror development process, the grinding phase, can take years.

Exploiting Data Similarity to Reduce Memory Footprints

DTIC Science & Technology

2011-01-01

leslie3d Fortran Computational Fluid Dynamics (CFD) application 122. tachyon C Parallel Ray Tracing application 128.GAPgeofem C and Fortran Simulates...benefits most from SBLLmalloc; LAMMPS, which shows moderate similarity from primarily zero pages; and 122. tachyon , a parallel ray- tracing application...similarity across MPI tasks. They primarily are zero- pages although a small fraction (≈10%) are non-zero pages. 122. tachyon is an image rendering

Trace and Contextual Fear Conditioning Require Neural Activity and NMDA Receptor-Dependent Transmission in the Medial Prefrontal Cortex

ERIC Educational Resources Information Center

Gilmartin, Marieke R.; Helmstetter, Fred J.

2010-01-01

The contribution of the medial prefrontal cortex (mPFC) to the formation of memory is a subject of considerable recent interest. Notably, the mechanisms supporting memory acquisition in this structure are poorly understood. The mPFC has been implicated in the acquisition of trace fear conditioning, a task that requires the association of a…

Two new methods used to simulate the circumferential solar flux density concentrated on the absorber of a parabolic trough solar collector

NASA Astrophysics Data System (ADS)

Guo, Minghuan; Wang, Zhifeng; Sun, Feihu

2016-05-01

The optical efficiencies of a solar trough concentrator are important to the whole thermal performance of the solar collector, and the outer surface of the tube absorber is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated solar flux density distributions on the tube absorber of a parabolic trough solar collector for various sun beam incident angles, with main optical errors considered. Since the solar trough concentrators are linear focusing, it is much of interest to investigate the solar flux density distribution on the cross-section profile of the tube absorber, rather than the flux density distribution along the focal line direction. Although a few integral approaches based on the "solar cone" concept were developed to compute the concentrated flux density for some simple trough concentrator geometries, all those integral approaches needed special integration routines, meanwhile, the optical parameters and geometrical properties of collectors also couldn't be changed conveniently. Flexible Monte Carlo ray trace (MCRT) methods are widely used to simulate the more accurate concentrated flux density distribution for compound parabolic solar trough concentrators, while generally they are quite time consuming. In this paper, we first mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the cross-section flux density on the region of interest of the tube absorber. For BRT, bundles of rays are launched at absorber-surface points of interest, directly go through the glass cover of the absorber, strike on the uniformly sampled mirror segment centers in the close-related surface region of the parabolic reflector, and then direct to the effective solar cone around the incident sun beam direction after the virtual backward reflection. All the optical errors are convoluted into the effective solar cone. The brightness distribution of the effective solar cone is supposed to be circular Gaussian type. Then a parabolic trough solar collector of Euro Trough 150 is used as an example object to apply this BRT method. Euro Trough 150 is composed of RP3 mirror facets, with the focal length of 1.71m, aperture width of 5.77m, outer tube diameter of 0.07m. Also to verify the simulated flux density distributions, we establish a modified MCRT method. For this modified MCRT method, the random rays with weighted energy elements are launched in the close-related rectangle region in the aperture plane of the parabolic concentrator and the optical errors are statistically modeled in the stages of forward ray tracing process. Given the same concentrator geometric parameters and optical error values, the simulated results from these two ray tracing methods are in good consistence. The two highlights of this paper are the new optical simulation method, BRT, and figuring out the close-related mirror surface region for BRT and the close-related aperture region for MCRT in advance to effectively simulate the solar flux distribution on the absorber surface of a parabolic trough collector.

The role of cortical sensorimotor oscillations in action anticipation.

PubMed

Denis, Dan; Rowe, Richard; Williams, A Mark; Milne, Elizabeth

2017-02-01

The human mirror neuron system is believed to play an important role in facilitating the ability of athletes to anticipate the actions of an opponent. This system is often assessed with EEG by measuring event-related changes in mu (8-13Hz) sensorimotor oscillations. However, traditional channel-based analyses of this measure are flawed in that due to volume conduction effects mu and non-mu alpha activity can become mixed. This flaw means it is unclear the extent to which mu activity indexes the mirror system, as opposed to other processes such as attentional demand. As a solution to this problem, we use independent component analysis to separate out the underlying brain processes during a tennis-related action observation and anticipation task. We investigated expertise-related differences in independent component activity. Experienced tennis players (N=18) were significantly more accurate than unexperienced novices (N=21) on the anticipation task. EEG results found significant group differences in both the mu and beta (15-25Hz) frequency bands in sensorimotor components, with earlier and greater desynchronisation in the experienced tennis players. In particular, only experienced players showed desynchronisation in the high mu (11-13Hz) band. No group differences were found in posterior alpha components. These results show for the first time that expertise differences during action observation and anticipation are unique to sensorimotor sources, and that no expertise-related differences exist in attention modulated, posterior alpha sources. As such, this paper provides a much cleaner measure of the human mirror system during action observation, and its modulation by motor expertise, than has been possible in previous work. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Smelling themselves: Dogs investigate their own odours longer when modified in an "olfactory mirror" test.

PubMed

Horowitz, Alexandra

2017-10-01

While domestic dogs, Canis familiaris, have been found to be skillful at social cognitive tasks and even some meta-cognitive tasks, they have not passed the test of mirror self-recognition (MSR). Acknowledging the motivational and sensory challenges that might hinder performance, even before the question of self-recognition is broached, this study creates and enacts a novel design extrapolated from the species' natural behaviour. Given dogs' use of olfactory signals in communication, this experiment presents dogs with various canisters for approach and investigation. Each holds an odorous stimulus: in the critical test, either an "olfactory mirror" of the subject - the dog's own urine - or one in which the odour stimulus is modified. By looking at subjects' investigation times of each canister, it is shown that dogs distinguish between the olfactory "image" of themselves when modified: investigating their own odour for longer when it had an additional odour accompanying it than when it did not. Such behaviour implies a recognition of the odour as being of or from "themselves." The ecological validity of this odour presentation is examined by presenting to the subjects odours of other known or unknown dogs: dogs spend longer investigating the odour of other dogs than their own odour. Finally, in a second experiment, subjects spent longer with the modified stimulus than with the modified odour by itself, indicating that novelty alone does not explain the dogs' behavior. This study translates the MSR study for a species whose primary sensory modality is olfaction, and finds both that natural sniffing behaviour can be replicated in the lab and that dogs show more investigative interest in their own odours when modified. Copyright © 2017 Elsevier B.V. All rights reserved.

Musculoskeletal model-based control interface mimics physiologic hand dynamics during path tracing task

NASA Astrophysics Data System (ADS)

Crouch, Dustin L.; (Helen Huang, He

2017-06-01

Objective. We investigated the feasibility of a novel, customizable, simplified EMG-driven musculoskeletal model for estimating coordinated hand and wrist motions during a real-time path tracing task. Approach. A two-degree-of-freedom computational musculoskeletal model was implemented for real-time EMG-driven control of a stick figure hand displayed on a computer screen. After 5-10 minutes of undirected practice, subjects were given three attempts to trace 10 straight paths, one at a time, with the fingertip of the virtual hand. Able-bodied subjects completed the task on two separate test days. Main results. Across subjects and test days, there was a significant linear relationship between log-transformed measures of accuracy and speed (Pearson’s r  =  0.25, p  <  0.0001). The amputee subject could coordinate movement between the wrist and MCP joints, but favored metacarpophalangeal joint motion more highly than able-bodied subjects in 8 of 10 trials. For able-bodied subjects, tracing accuracy was lower at the extremes of the model’s range of motion, though there was no apparent relationship between tracing accuracy and fingertip location for the amputee. Our result suggests that, unlike able-bodied subjects, the amputee’s motor control patterns were not accustomed to the multi-joint dynamics of the wrist and hand, possibly as a result of post-amputation cortical plasticity, disuse, or sensory deficits. Significance. To our knowledge, our study is one of very few that have demonstrated the real-time simultaneous control of multi-joint movements, especially wrist and finger movements, using an EMG-driven musculoskeletal model, which differs from the many data-driven algorithms that dominate the literature on EMG-driven prosthesis control. Real-time control was achieved with very little training and simple, quick (~15 s) calibration. Thus, our model is potentially a practical and effective control platform for multifunctional myoelectric prostheses that could restore more life-like hand function for individuals with upper limb amputation.

Designing a Knowledge Representation Approach for the Generation of Pedagogical Interventions by MTTs

ERIC Educational Resources Information Center

Paquette, Luc; Lebeau, Jean-François; Beaulieu, Gabriel; Mayers, André

2015-01-01

Model-tracing tutors (MTTs) have proven effective for the tutoring of well-defined tasks, but the pedagogical interventions they produce are limited and usually require the inclusion of pedagogical content, such as text message templates, in the model of the task. The capability to generate pedagogical content would be beneficial to MTT…

Investigating the Construct Measured by Banked Gap-Fill Items: Evidence from Eye-Tracking

ERIC Educational Resources Information Center

McCray, Gareth; Brunfaut, Tineke

2018-01-01

This study investigates test-takers' processing while completing banked gap-fill tasks, designed to test reading proficiency, in order to test theoretically based expectations about the variation in cognitive processes of test-takers across levels of performance. Twenty-eight test-takers' eye traces on 24 banked gap-fill items (on six tasks) were…

Signaling Task Awareness in Think-Aloud Protocols from Students Selecting Relevant Information from Text

ERIC Educational Resources Information Center

Schellings, Gonny L. M.; Broekkamp, Hein

2011-01-01

Self-regulated learning has been described as an adaptive process: students adapt their learning strategies for attaining different learning goals. In order to be adaptive, students must have a clear notion of what the task requirements consist of. Both trace data and questionnaire data indicate that students adapt study strategies in limited ways…

Tracing the Cascade of Children's Insecurity in the Interparental Relationship: The Role of Stage-Salient Tasks

ERIC Educational Resources Information Center

Davies, Patrick T.; Manning, Liviah G.; Cicchetti, Dante

2013-01-01

This study examined whether children’s difficulties with stage-salient tasks served as an explanatory mechanism in the pathway between their insecurity in the interparental relationship and their disruptive behavior problems. Using a multimethod, multi-informant design, 201 two-year-old children and their mothers participated in 3 annual…

Mind Mirror Projects: A Tool for Integrating Critical Thinking into the English Language Classroom

ERIC Educational Resources Information Center

Tully, Matthew M.

2009-01-01

Identifying a point of view can be a complex task in any language. By analyzing what characters say, think, and do throughout a story, readers can observe how points of view tend to change over time. Easier said than done, this ability to climb inside the mind of a character can help students as they analyze personalities found in literature,…

Use of a Tracing Task to Assess Visuomotor Performance: Effects of Age, Sex, and Handedness

PubMed Central

2013-01-01

Background. Visuomotor abnormalities are common in aging and age-related disease, yet difficult to quantify. This study investigated the effects of healthy aging, sex, and handedness on the performance of a tracing task. Participants (n = 150, aged 21–95 years, 75 females) used a stylus to follow a moving target around a circle on a tablet computer with their dominant and nondominant hands. Participants also performed the Trail Making Test (a measure of executive function). Methods. Deviations from the circular path were computed to derive an “error” time series. For each time series, absolute mean, variance, and complexity index (a proposed measure of system functionality and adaptability) were calculated. Using the moving target and stylus coordinates, the percentage of task time within the target region and the cumulative micropause duration (a measure of motion continuity) were computed. Results. All measures showed significant effects of aging (p < .0005). Post hoc age group comparisons showed that with increasing age, the absolute mean and variance of the error increased, complexity index decreased, percentage of time within the target region decreased, and cumulative micropause duration increased. Only complexity index showed a significant difference between dominant versus nondominant hands within each age group (p < .0005). All measures showed relationships to the Trail Making Test (p < .05). Conclusions. Measures derived from a tracing task identified performance differences in healthy individuals as a function of age, sex, and handedness. Studies in populations with specific neuromotor syndromes are warranted to test the utility of measures based on the dynamics of tracking a target as a clinical assessment tool. PMID:23388876

Photovoltaic applications of Compound Parabolic Concentrator (CPC)

NASA Technical Reports Server (NTRS)

Winston, R.

1975-01-01

The use of a compound parabolic concentrator as field collector, in conjunction with a primary focusing concentrator for photovoltaic applications is studied. The primary focusing concentrator can be a parabolic reflector, an array of Fresnel mirrors, a Fresnel lens or some other lens. Silicon solar cell grid structures are proposed that increase efficiency with concentration up to 10 suns. A ray tracing program has been developed to determine energy distribution at the exit of a compound parabolic concentrator. Projected total cost of a CPC/solar cell system will be between 4 and 5 times lower than for flat plate silicon cell arrays.

Long-Term Memory and the Control of Attentional Control

PubMed Central

Mayr, Ulrich; Kuhns, David; Hubbard, Jason

2014-01-01

Task-switch costs and in particular the switch-cost asymmetry (i.e., the larger costs of switching to a dominant than a non-dominant task) are usually explained in terms of trial-to-trial carry-over of task-specific control settings. Here we argue that task switches are just one example of situations that trigger a transition from working-memory maintenance to updating, thereby opening working memory to interference from long-term memory. We used a new paradigm that requires selecting a spatial location either on the basis of a central cue (i.e., endogenous control of attention) or a peripheral, sudden onset (i.e., exogenous control of attention). We found a strong cost asymmetry that occurred even after short interruptions of otherwise single-task blocks (Exp. 1-3), but that was much stronger when participants had experienced the competing task under conditions of conflict (Exp. 1-2). Experiment 3 showed that the asymmetric costs were due to interruptions per se, rather than to associative interference tied to specific interruption activities. Experiment 4 generalized the basic pattern across interruptions varying in length or control demands and Experiment 5 across primary tasks with response-selection conflict rather than attentional conflict. Combined, the results support a model in which costs of selecting control settings arise when (a) potentially interfering memory traces have been encoded in long-term memory and (b) working-memory is forced from a maintenance mode into an updating mode (e.g., through task interruptions), thereby allowing unwanted retrieval of the encoded memory traces. PMID:24650696

Optimizing Opto-mechanical Performance Using Simple Tools and Techniques

NASA Astrophysics Data System (ADS)

Krajci, Tom

2009-05-01

You just purchased a modest setup for your observatory - perhaps a mass produced Schmidt-Cassegrain on a German equatorial mount. However, optically and mechanically it's not performing as well as you would like. What can you do? Some simple assessments and repairs may make all the difference. Assessments can be as easy as visual inspection of various mount components, such as the tripod, where gaps between components reduce stiffness or allow unexpected shifts when loads change. Some assessments are only slightly more involved. Main mirror flop can be evaluated by aligning the main telescope and finder on a bright star and then slewing to various parts of the sky. Pointing differences between the two will be readily apparent if this problem exists. Most mid-level mounts use worm drives, but often excessive spacing between worm and worm gear produces large, and unnecessary amounts of backlash. Visual inspection of your dovetail mounting system may leave doubts in your mind as to adequate stiffness. Imaging through the entire night may show you that your aluminum tube telescope causes excessive focus shift as temperature drops. Over time, your Schmidt-Cassegrain corrector plate may no longer be securely held by its retaining ring, and the same may apply to the secondary mirror cell. Repairs for these problems are often not difficult if you're mechanically inclined. Gaps in mount components can be eliminated with shims. Combating mirror flop may be the most difficult task. This can involve re-gluing the main mirror and bolting the main mirror cell in a fixed position. Corrector plate and secondary mirror cells can be improved with setscrews and shims - implementing sound kinematic principles. Worm gear spacing can often be adjusted with simple tools. This brief paper can't possibly cover all problems and solutions, but it can give you the proper mindset to looking at your system with a critical eye and implementing simple, inexpensive fixes. You may be pleasantly surprised by the improvements.

Time-Based Loss in Visual Short-Term Memory is from Trace Decay, not Temporal Distinctiveness

PubMed Central

Ricker, Timothy J.; Spiegel, Lauren R.; Cowan, Nelson

2014-01-01

There is no consensus as to why forgetting occurs in short-term memory tasks. In past work, we have shown that forgetting occurs with the passage of time, but there are two classes of theories that can explain this effect. In the present work, we investigate the reason for time-based forgetting by contrasting the predictions of temporal distinctiveness and trace decay in the procedure in which we have observed such loss, involving memory for arrays of characters or letters across several seconds. The first theory, temporal distinctiveness, predicts that increasing the amount of time between trials will lead to less proactive interference, resulting in less forgetting across a retention interval. In the second theory, trace decay, temporal distinctiveness between trials is irrelevant to the loss over a retention interval. Using visual array change detection tasks in four experiments, we find small proactive interference effects on performance under some specific conditions, but no concomitant change in the effect of a retention interval. We conclude that trace decay is the more suitable class of explanations of the time-based forgetting in short-term memory that we have observed, and we suggest the need for further clarity in what the exact basis of that decay may be. PMID:24884646

Deficits in hippocampus-mediated Pavlovian conditioning in endogenous hypercortisolism.

PubMed

Grillon, Christian; Smith, Kathryn; Haynos, Ann; Nieman, Lynnette K

2004-12-01

Elevated endogenous levels of corticosteroids cause neural dysfunction and loss, especially within the hippocampus, as well as cognitive impairment in hippocampus-mediated tasks. Because Cushing's syndrome patients suffer from hypercortisolism, they represent a unique opportunity to study the impact of elevated glucocorticoids on cognitive functions. The aim of this study was to examine the performance of Cushing's syndrome patients on trace eyeblink conditioning, a cross-species, hippocampal-mediated test of learning and memory. Eleven Cushing's syndrome patients and 11 healthy control subjects participated in an eyeblink trace conditioning test (1000-msec trace) and a task of declarative memory for words. Salivary cortisol was collected in both the patients and the control subjects, and urinary free cortisol was collected in the patients only. The patients exhibited fewer conditional responses and remembered fewer words, compared with the control subjects. Cortisol levels correlated with immediate and delayed declarative memory only. Conditional response correlated with delayed recall after controlling for the magnitude of unconditional response. The integrity of the hippocampus seems to be compromised in Cushing's syndrome patients. Trace eyeblink conditioning might be useful both as a clinical tool to examine changes in hippocampus function in Cushing's disease patients and as a translational tool of research on the impact of chronic exposure of glucocorticoids.

Consolidation and restoration of memory traces in working memory.

PubMed

De Schrijver, Sébastien; Barrouillet, Pierre

2017-10-01

Consolidation is the process through which ephemeral sensory traces are transformed into more stable short-term memory traces. It has been shown that consolidation plays a crucial role in working memory (WM) performance, by strengthening memory traces that then better resist interference and decay. In a recent study, Bayliss, Bogdanovs, and Jarrold (Journal of Memory and Language, 81, 34-50, 2015) argued that this process is separate from the processes known to restore WM traces after degradation, such as attentional refreshing and verbal rehearsal. In the present study, we investigated the relationship between the two types of processes in the context of WM span tasks. Participants were presented with series of letters for serial recall, each letter being followed by four digits for parity judgment. Consolidation opportunity was manipulated by varying the delay between each letter and the first digit to be processed, while opportunities for restoration were manipulated by varying the pace at which the parity task had to be performed (i.e., its cognitive load, or CL). Increasing the time available for either consolidation or restoration resulted in higher WM spans, with some substitutability between the two processes. Accordingly, when consolidation time was added to restoration time in the calculation of CL, the new resulting index, called extended CL, proved a very good predictor of recall performance, a finding also observed when verbal rehearsal was prevented by articulatory suppression. This substitutability between consolidation and restoration suggests that both processes may rely on the same mechanisms.

Optical MEMS for Earth observation

NASA Astrophysics Data System (ADS)

Liotard, Arnaud; Viard, Thierry; Noell, Wilfried; Zamkotsian, Frédéric; Freire, Marco; Guldimann, Benedikt; Kraft, Stefan

2017-11-01

Due to the relatively large number of optical Earth Observation missions at ESA, this area is interesting for new space technology developments. In addition to their compactness, scalability and specific task customization, optical MEMS could generate new functions not available with current technologies and are thus candidates for the design of future space instruments. Most mature components for space applications are the digital mirror arrays, the micro-deformable mirrors, the programmable micro diffraction gratings and tiltable micromirrors. A first selection of market-pull and techno-push concepts is done. In addition, some concepts are coming from outside Earth Observation. Finally two concepts are more deeply analyzed. The first concept is a programmable slit for straylight control for space spectro-imagers. This instrument is a push-broom spectroimager for which some images cannot be exploited because of bright sources in the field-of-view. The proposed concept consists in replacing the current entrance spectrometer slit by an active row of micro-mirrors. The MEMS will permit to dynamically remove the bright sources and then to obtain a field-of-view with an optically enhanced signal-to-noise ratio. The second concept is a push-broom imager for which the acquired spectrum can be tuned by optical MEMS. This system is composed of two diffractive elements and a digital mirror array. The first diffractive element spreads the spectrum. A micromirror array is set at the location of the spectral focal plane. By putting the micro-mirrors ON or OFF, we can select parts of field-of-view or spectrum. The second diffractive element then recombines the light on a push-broom detector. Dichroics filters, strip filter, band-pass filter could be replaced by a unique instrument.

Altered Brain Activation During Action Imitation and Observation in Schizophrenia: A Translational Approach to Investigating Social Dysfunction in Schizophrenia

PubMed Central

Thakkar, Katharine N.; Peterman, Joel S.; Park, Sohee

2015-01-01

Objective Social impairments are a key feature of schizophrenia, but their underlying mechanisms are poorly understood. Imitation, a process through which we understand the minds of others, involves the so-called mirror neuron system, a network comprising the inferior parietal lobe, inferior frontal gyrus, and posterior superior temporal sulcus. The authors examined mirror neuron system function in schizophrenia. Method Sixteen medicated schizophrenia patients and 16 healthy comparison subjects performed an action imitation/ observation task during functional MRI. Participants saw a video of a moving hand or spatial cue and were instructed to either execute finger movements associated with the stimulus or simply observe. Activation in the mirror neuron system was measured during imitative versus nonimitative actions and observation of a moving hand versus a moving spatial cue. These contrasts were compared across groups. Results Activation in the mirror neuron system was less specific for imitation in schizophrenia. Relative to healthy subjects, patients had reduced activity in the posterior superior temporal sulcus during imitation and greater activity in the posterior superior temporal sulcus and inferior parietal lobe during nonimitative action. Patients also showed reduced activity in these regions during action observation. Mirror neuron system activation was related to symptom severity and social functioning in patients and to schizotypal syndrome in comparison subjects. Conclusions Given the role of the inferior parietal lobe and posterior superior temporal sulcus in imitation and social cognition, impaired imitative ability in schizophrenia may stem from faulty perception of biological motion and transformations from perception to action. These findings extend our understanding of social dysfunction in schizophrenia. PMID:24626638

Trace Contraband Detection Field-Test by the South Texas Specialized Crimes and Narcotics Task Force

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

Hannum, David W.; Shannon, Gary W.

This report describes the collaboration between the South Texas Specialized Crimes and Narcotics Task Force (STSCNTF) and Sandia National Laboratories (SNL) in a field test that provided prototype hand-held trace detection technology for use in counter-drug operations. The National Institute of Justice (NIJ)/National Law Enforcement and Corrections Technology Center (NLECTC)/Border Research and Technology Center (BRTC) was contacted by STSCNTF for assistance in obtaining cutting-edge technology. The BRTC created a pilot project for Sandia National Laboratories (SNL) and the STSCNTF for the use of SNL’s Hound, a hand-held sample collection and preconcentration system that, when combined with a commercial chemical detector,more » can be used for the trace detection of illicit drugs and explosives. The STSCNTF operates in an area of high narcotics trafficking where methods of concealment make the detection of narcotics challenging. Sandia National Laboratories’ (SNL) Contraband Detection Department personnel provided the Hound system hardware and operational training. The Hound system combines the GE VaporTracer2, a hand-held commercial chemical detector, with an SNL-developed sample collection and preconcentration system. The South Texas Task force reported a variety of successes, including identification of a major shipment of methamphetamines, the discovery of hidden compartments in vehicles that contained illegal drugs and currency used in drug deals, and the identification of a suspect in a nightclub shooting. The main advantage of the hand-held trace detection unit is its ability to quickly identify the type of chemical (drugs or explosives) without a long lag time for laboratory analysis, which is the most common analysis method for current law enforcement procedures.« less

8s, a numerical simulator of the challenging optical calibration of the E-ELT adaptive mirror M4

NASA Astrophysics Data System (ADS)

Briguglio, Runa; Pariani, Giorgio; Xompero, Marco; Riccardi, Armando; Tintori, Matteo; Lazzarini, Paolo; Spanò, Paolo

2016-07-01

8s stands for Optical Test TOwer Simulator (with 8 read as in italian 'otto'): it is a simulation tool for the optical calibration of the E-ELT deformable mirror M4 on its test facility. It has been developed to identify possible criticalities in the procedure, evaluate the solutions and estimate the sensitivity to environmental noise. The simulation system is composed by the finite elements model of the tower, the analytic influence functions of the actuators, the ray tracing propagation of the laser beam through the optical surfaces. The tool delivers simulated phasemaps of M4, associated with the current system status: actuator commands, optics alignment and position, beam vignetting, bench temperature and vibrations. It is possible to simulate a single step of the optical test of M4 by changing the system parameters according to a calibration procedure and collect the associated phasemap for performance evaluation. In this paper we will describe the simulation package and outline the proposed calibration procedure of M4.

Survey mirrors and lenses and their required surface accuracy. Volume 1. Technical report. Final report for September 15, 1978-December 1, 1979

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

Beesing, M. E.; Buchholz, R. L.; Evans, R. A.

1980-01-01

An investigation of the optical performance of a variety of concentrating solar collectors is reported. The study addresses two important issues: the accuracy of reflective or refractive surfaces required to achieve specified performance goals, and the effect of environmental exposure on the performance concentrators. To assess the importance of surface accuracy on optical performance, 11 tracking and nontracking concentrator designs were selected for detailed evaluation. Mathematical models were developed for each design and incorporated into a Monte Carlo ray trace computer program to carry out detailed calculations. Results for the 11 concentrators are presented in graphic form. The models andmore » computer program are provided along with a user's manual. A survey data base was established on the effect of environmental exposure on the optical degradation of mirrors and lenses. Information on environmental and maintenance effects was found to be insufficient to permit specific recommendations for operating and maintenance procedures, but the available information is compiled and reported and does contain procedures that other workers have found useful.« less

SAO mission support software and data standards, version 1.0

NASA Technical Reports Server (NTRS)

Hsieh, P.

1993-01-01

This document defines the software developed by the SAO AXAF Mission Support (MS) Program and defines standards for the software development process and control of data products generated by the software. The SAO MS is tasked to develop and use software to perform a variety of functions in support of the AXAF mission. Software is developed by software engineers and scientists, and commercial off-the-shelf (COTS) software is used either directly or customized through the use of scripts to implement analysis procedures. Software controls real-time laboratory instruments, performs data archiving, displays data, and generates model predictions. Much software is used in the analysis of data to generate data products that are required by the AXAF project, for example, on-orbit mirror performance predictions or detailed characterization of the mirror reflection performance with energy.

Advanced optical delay line demonstrator

NASA Astrophysics Data System (ADS)

van den Dool, Teun; Kamphues, Fred; Fouss, B.; Henrioulle, K.; Hogenhuis, Harm

2004-09-01

TNO TPD, in cooperation with Micromega-Dynamics and Dutch Space, has designed an advanced Optical Delay Line (ODL) for use in future ground based and space interferometry missions. The work is performed under NIVR contract in preparation for GENIE and DARWIN. Using the ESO PRIMA DDL requirements as a baseline, the delay line can be used for PRIMA and GENIE without any modifications. The delay line design is modular and flexible, which makes scaling for other applications a relatively easy task. The ODL has a single linear motor actuator for Optical Path Difference (OPD) control, driving a two-mirror cat"s eye with SiC mirrors and CFRP structure. Magnetic bearings provide frictionless and wear free operation with zerohysteresis. The delay line is currently being assembled and will be subjected to a comprehensive test program in the second half of 2004.

Stable Isotope Mapping of Alaskan Grasses and Marijuana

NASA Astrophysics Data System (ADS)

Booth, A. L.; Wooller, M. J.

2008-12-01

The spatial variation of isotope signatures in organic material is a useful forensic tool, particularly when applied to the task of tracking the production and distribution of plant-derived illicit drugs. In order to identify the likely grow-locations of drugs such as marijuana from unknown locations (i.e., confiscated during trafficking), base isotope maps are needed that include measurements of plants from known grow-locations. This task is logistically challenging in remote, large regions such as Alaska. We are therefore investigating the potential of supplementing our base (marijuana) isotope maps with data derived from other plants from known locations and with greater spatial coverage in Alaska. These currently include >150 samples of modern C3 grasses (Poaceae) as well as marijuana samples (n = 18) from known grow-locations across the state. We conducted oxygen, carbon and nitrogen stable isotope analyses of marijuana and grasses (Poaceae). Poaceae samples were obtained from the University of Alaska Fairbanks (UAF) Museum of the North herbarium collection, originally collected by field botanists from around Alaska. Results indicate that the oxygen isotopic composition of these grasses range from 10‰ to 30‰, and broadly mirror the spatial pattern of water isotopes in Alaska. Our marijuana samples were confiscated around the state of Alaska and supplied to us by the UAF Police Department. δ13C, δ15N and δ18O values exhibit geographic patterns similar to the modern grasses, but carbon and nitrogen isotopes of some marijuana plants appear to be influenced by additional factors related to indoor growing conditions (supplementary CO2 sources and the application of organic fertilizer). As well as providing a potential forensic resource, our Poaceae isotope maps could serve additional value by providing resources for studying ecosystem nutrient cycling, for tracing natural ecological processes (i.e., animal migration and food web dynamics) and providing modern data for comparison with isotope analyses conducted on fossil leaf material in paleoecological studies.

It Pays to Go Off-Track: Practicing with Error-Augmenting Haptic Feedback Facilitates Learning of a Curve-Tracing Task

PubMed Central

Williams, Camille K.; Tremblay, Luc; Carnahan, Heather

2016-01-01

Researchers in the domain of haptic training are now entering the long-standing debate regarding whether or not it is best to learn a skill by experiencing errors. Haptic training paradigms provide fertile ground for exploring how various theories about feedback, errors and physical guidance intersect during motor learning. Our objective was to determine how error minimizing, error augmenting and no haptic feedback while learning a self-paced curve-tracing task impact performance on delayed (1 day) retention and transfer tests, which indicate learning. We assessed performance using movement time and tracing error to calculate a measure of overall performance – the speed accuracy cost function. Our results showed that despite exhibiting the worst performance during skill acquisition, the error augmentation group had significantly better accuracy (but not overall performance) than the error minimization group on delayed retention and transfer tests. The control group’s performance fell between that of the two experimental groups but was not significantly different from either on the delayed retention test. We propose that the nature of the task (requiring online feedback to guide performance) coupled with the error augmentation group’s frequent off-target experience and rich experience of error-correction promoted information processing related to error-detection and error-correction that are essential for motor learning. PMID:28082937

Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Rudich, Y.; Brown, S. S.

2015-09-01

Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99933 ± 0.00003 (670 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.49 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device (CCD) array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity enhanced spectroscopy and cavity ringdown spectroscopy agree within 2 % (slope for linear fit = 0.98 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity enhanced spectroscopy and calculated based on flow dilution are also well-correlated, with r2 = 0.9998. During constant, mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1-min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically-based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to trace gases, this approach will be appropriate for measurements of aerosol extinction in ambient air, and this spectral region is important for characterizing the strong ultraviolet absorption by brown carbon aerosol.

Neurobiological and Memory Models of Risky Decision Making in Adolescents versus Young Adults

ERIC Educational Resources Information Center

Reyna, Valerie F.; Estrada, Steven M.; DeMarinis, Jessica A.; Myers, Regina M.; Stanisz, Janine M.; Mills, Britain A.

2011-01-01

Predictions of fuzzy-trace theory and neurobiological approaches are examined regarding risk taking in a classic decision-making task--the framing task--as well as in the context of real-life risk taking. We report the 1st study of framing effects in adolescents versus adults, varying risk and reward, and relate choices to individual differences,…

Transcriptional profiling reveals regulated genes in the hippocampus during memory formation

NASA Technical Reports Server (NTRS)

Donahue, Christine P.; Jensen, Roderick V.; Ochiishi, Tomoyo; Eisenstein, Ingrid; Zhao, Mingrui; Shors, Tracey; Kosik, Kenneth S.

2002-01-01

Transcriptional profiling (TP) offers a powerful approach to identify genes activated during memory formation and, by inference, the molecular pathways involved. Trace eyeblink conditioning is well suited for the study of regional gene expression because it requires the hippocampus, whereas the highly parallel task, delay conditioning, does not. First, we determined when gene expression was most regulated during trace conditioning. Rats were exposed to 200 trials per day of paired and unpaired stimuli each day for 4 days. Changes in gene expression were most apparent 24 h after exposure to 200 trials. Therefore, we profiled gene expression in the hippocampus 24 h after 200 trials of trace eyeblink conditioning, on multiple arrays using additional animals. Of 1,186 genes on the filter array, seven genes met the statistical criteria and were also validated by real-time polymerase chain reaction. These genes were growth hormone (GH), c-kit receptor tyrosine kinase (c-kit), glutamate receptor, metabotropic 5 (mGluR5), nerve growth factor-beta (NGF-beta), Jun oncogene (c-Jun), transmembrane receptor Unc5H1 (UNC5H1), and transmembrane receptor Unc5H2 (UNC5H2). All these genes, except for GH, were downregulated in response to trace conditioning. GH was upregulated; therefore, we also validated the downregulation of the GH inhibitor, somatostatin (SST), even though it just failed to meet criteria on the arrays. By during situ hybridization, GH was expressed throughout the cell layers of the hippocampus in response to trace conditioning. None of the genes regulated in trace eyeblink conditioning were similarly affected by delay conditioning, a task that does not require the hippocampus. These findings demonstrate that transcriptional profiling can exhibit a repertoire of genes sensitive to the formation of hippocampal-dependent associative memories.

The penta-prism LTP: A long-trace-profiler with stationary optical head and moving penta prism

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

Qian, S.; Jark, W.; Takacs, P.Z.

1995-03-01

Metrology requirements for optical components for third-generation synchrotron sources are taxing the state of the art in manufacturing technology. We have investigated a number of error sources in a commercial figure measurement instrument, the Long-Trace-Profiler II, and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, as in the original pencil-beam interferometer design of von Bieren, the stability of the optical system is greatly improved, and the remaining errormore » signals can be corrected by a simple reference beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.« less

Nonimaging optics

NASA Astrophysics Data System (ADS)

Winston, Roland

1991-03-01

Various uses of nonimaging concentrators and advances in the field of nonimaging optics are discussed. A nonimaging concentrator acts as a type of funnel for light by collecting and intensifying radiation far better than a lens or mirror would. It thus has found useful applications in fields ranging from high-energy physics to solar energy. The history of the field of nonimaging optics is traced, beginning with the design of the first compound parabolic concentrators in the mid-1960s. It is noted that at present there are two known ways to design nonimaging concentrators: the edge-ray method and the geometric vector flux approach. The use of nonimaging optical devices in the design of nontracking solar concentrators is traced. It is noted that the upper limit of concentration turns out to be about 46,000 times the intensity of sunlight at the surface of the earth. Methods used to maximize this concentration are discussed. The development and use of a solar-pumped laser which would have applications in satellite communications are discussed.

Implicit transfer of spatial structure in visuomotor sequence learning.

PubMed

Tanaka, Kanji; Watanabe, Katsumi

2014-11-01

Implicit learning and transfer in sequence learning are essential in daily life. Here, we investigated the implicit transfer of visuomotor sequences following a spatial transformation. In the two experiments, participants used trial and error to learn a sequence consisting of several button presses, known as the m×n task (Hikosaka et al., 1995). After this learning session, participants learned another sequence in which the button configuration was spatially transformed in one of the following ways: mirrored, rotated, and random arrangement. Our results showed that even when participants were unaware of the transformation rules, accuracy of transfer session in the mirrored and rotated groups was higher than that in the random group (i.e., implicit transfer occurred). Both those who noticed the transformation rules and those who did not (i.e., explicit and implicit transfer instances, respectively) showed faster performance in the mirrored sequences than in the rotated sequences. Taken together, the present results suggest that people can use their implicit visuomotor knowledge to spatially transform sequences and that implicit transfers are modulated by a transformation cost, similar to that in explicit transfer. Copyright © 2014 Elsevier B.V. All rights reserved.

Automatic extraction of the mid-sagittal plane using an ICP variant

NASA Astrophysics Data System (ADS)

Fieten, Lorenz; Eschweiler, Jörg; de la Fuente, Matías; Gravius, Sascha; Radermacher, Klaus

2008-03-01

Precise knowledge of the mid-sagittal plane is important for the assessment and correction of several deformities. Furthermore, the mid-sagittal plane can be used for the definition of standardized coordinate systems such as pelvis or skull coordinate systems. A popular approach for mid-sagittal plane computation is based on the selection of anatomical landmarks located either directly on the plane or symmetrically to it. However, the manual selection of landmarks is a tedious, time-consuming and error-prone task, which requires great care. In order to overcome this drawback, previously it was suggested to use the iterative closest point (ICP) algorithm: After an initial mirroring of the data points on a default mirror plane, the mirrored data points should be registered iteratively to the model points using rigid transforms. Finally, a reflection transform approximating the cumulative transform could be extracted. In this work, we present an ICP variant for the iterative optimization of the reflection parameters. It is based on a closed-form solution to the least-squares problem of matching data points to model points using a reflection. In experiments on CT pelvis and skull datasets our method showed a better ability to match homologous areas.

Multiview hyperspectral topography of tissue structural and functional characteristics

NASA Astrophysics Data System (ADS)

Liu, Peng; Huang, Jiwei; Zhang, Shiwu; Xu, Ronald X.

2016-01-01

Accurate and in vivo characterization of structural, functional, and molecular characteristics of biological tissue will facilitate quantitative diagnosis, therapeutic guidance, and outcome assessment in many clinical applications, such as wound healing, cancer surgery, and organ transplantation. We introduced and tested a multiview hyperspectral imaging technique for noninvasive topographic imaging of cutaneous wound oxygenation. The technique integrated a multiview module and a hyperspectral module in a single portable unit. Four plane mirrors were cohered to form a multiview reflective mirror set with a rectangular cross section. The mirror set was placed between a hyperspectral camera and the target biological tissue. For a single image acquisition task, a hyperspectral data cube with five views was obtained. The five-view hyperspectral image consisted of a main objective image and four reflective images. Three-dimensional (3-D) topography of the scene was achieved by correlating the matching pixels between the objective image and the reflective images. 3-D mapping of tissue oxygenation was achieved using a hyperspectral oxygenation algorithm. The multiview hyperspectral imaging technique was validated in a wound model, a tissue-simulating blood phantom, and in vivo biological tissue. The experimental results demonstrated the technical feasibility of using multiview hyperspectral imaging for 3-D topography of tissue functional properties.

Sea Slugs, Subliminal Pictures, and Vegetative State Patients: Boundaries of Consciousness in Classical Conditioning

PubMed Central

Bekinschtein, Tristan A.; Peeters, Moos; Shalom, Diego; Sigman, Mariano

2011-01-01

Classical (trace) conditioning is a specific variant of associative learning in which a neutral stimulus leads to the subsequent prediction of an emotionally charged or noxious stimulus after a temporal gap. When conditioning is concurrent with a distraction task, only participants who can report the relationship (the contingency) between stimuli explicitly show associative learning. This suggests that consciousness is a prerequisite for trace conditioning. We review and question three main controversies concerning this view. Firstly, virtually all animals, even invertebrate sea slugs, show this type of learning; secondly, unconsciously perceived stimuli may elicit trace conditioning; and thirdly, some vegetative state patients show trace learning. We discuss and analyze these seemingly contradictory arguments to find the theoretical boundaries of consciousness in classical conditioning. We conclude that trace conditioning remains one of the best measures to test conscious processing in the absence of explicit reports. PMID:22164148

Outlines of a multiple trace theory of temporal preparation.

PubMed

Los, Sander A; Kruijne, Wouter; Meeter, Martijn

2014-01-01

We outline a new multiple trace theory of temporal preparation (MTP), which accounts for behavior in reaction time (RT) tasks in which the participant is presented with a warning stimulus (S1) followed by a target stimulus (S2) that requires a speeded response. The theory assumes that during the foreperiod (FP; the S1-S2 interval) inhibition is applied to prevent premature response, while a wave of activation occurs upon the presentation of S2. On each trial, these actions are stored in a separate memory trace, which, jointly with earlier formed memory traces, starts contributing to preparation on subsequent trials. We show that MTP accounts for classic effects in temporal preparation, including mean RT-FP functions observed under a variety of FP distributions and asymmetric sequential effects. We discuss the advantages of MTP over other accounts of these effects (trace-conditioning and hazard-based explanations) and suggest a critical experiment to empirically distinguish among them.

Basic-Level Category Discriminations by 7- and 9-Month-Olds in an Object Examination Task.

ERIC Educational Resources Information Center

Mareschal, Denis; Powell, Daisy; Volein, Agnes

2003-01-01

Examined 7- and 9-month-olds' ability to categorize cats and dogs as separate from one another. Found that both groups formed a cat category that included novel cats but excluded a dog and an eagle, and formed a dog category that included novel dogs and a novel cat but excluded an eagle. Results mirrored those of 3- to 4-month-olds with visual…

Studies Related to Computer-Assisted Instruction. Semi-Annual Progress Report on Contract Nonr-624(18) October 1, 1968 through March 31, 1969.

ERIC Educational Resources Information Center

Glaser, Robert

A study of response latency in a drill-and-practice task showed that variability in latency measures could be reduced by the use of self-pacing procedures, but not by the detailed analysis of latency into separate components. Experiments carried out on instructional history variables in teaching a mirror image, oblique line discrimination, showed…

Structure of the Magnetotail Current Sheet

NASA Technical Reports Server (NTRS)

Larson, Douglas J.; Kaufmann, Richard L.

1996-01-01

An orbit tracing technique was used to generate current sheets for three magnetotail models. Groups of ions were followed to calculate the resulting cross-tail current. Several groups then were combined to produce a current sheet. The goal is a model in which the ions and associated electrons carry the electric current distribution needed to generate the magnetic field B in which ion orbits were traced. The region -20 R(sub E) less than x less than - 14 R(sub E) in geocentric solar magnetospheric coordinates was studied. Emphasis was placed on identifying the categories of ion orbits which contribute most to the cross-tail current and on gaining physical insight into the manner by which the ions carry the observed current distribution. Ions that were trapped near z = 0, ions that magnetically mirrored throughout the current sheet, and ions that mirrored near the Earth all were needed. The current sheet structure was determined primarily by ion magnetization currents. Electrons of the observed energies carried relatively little cross-tail current in these quiet time current sheets. Distribution functions were generated and integrated to evaluate fluid parameters. An earlier model in which B depended only on z produced a consistent current sheet, but it did not provide a realistic representation of the Earth's middle magnetotail. In the present study, B changed substantially in the x and z directions but only weakly in the y direction within our region of interest. Plasmas with three characteristic particle energies were used with each of the magnetic field models. A plasma was found for each model in which the density, average energy, cross-tail current, and bulk flow velocity agreed well with satellite observations.

Structure of the Magnetotail Current Sheet

NASA Technical Reports Server (NTRS)

Larson, Douglas J.; Kaufmann, Richard L.

1996-01-01

An orbit tracing technique was used to generate current sheets for three magnetotail models. Groups of ions were followed to calculate the resulting cross-tail current. Several groups then were combined to produce a current sheet. The goal is a model in which the ions and associated electrons carry the electric current distribution needed to generate the magnetic field B in which ion orbits were traced. The region -20 R(E) less than x less than -14 R(E) in geocentric solar magnetospheric coordinates was studied. Emphasis was placed on identifying the categories of ion orbits which contribute most to the cross-tail current and on gaining physical insight into the manner by which the ions carry the observed current distribution. Ions that were trapped near z = 0, ions that magnetically mirrored throughout the current sheet, and ions that mirrored near the Earth all were needed. The current sheet structure was determined primarily by ion magnetization currents. Electrons of the observed energies carried relatively little cross-tail current in these quiet time current sheets. Distribution functions were generated and integrated to evaluate fluid parameters. An earlier model in which B depended only on z produced a consistent current sheet, but it did not provide a realistic representation of the Earth's middle magnetotail. In the present study, B changed substantially in the x and z directions but only weakly in the y direction within our region of interest. Plasmas with three characteristic particle energies were used with each of the magnetic field models. A plasma was found for each model in which the density, average energy, cross-tail current, and bulk flow velocity agreed well with satellite observations.

A constrained rasch model of trace redintegration in serial recall.

PubMed

Roodenrys, Steven; Miller, Leonie M

2008-04-01

The notion that verbal short-term memory tasks, such as serial recall, make use of information in long-term as well as in short-term memory is instantiated in many models of these tasks. Such models incorporate a process in which degraded traces retrieved from a short-term store are reconstructed, or redintegrated (Schweickert, 1993), through the use of information in long-term memory. This article presents a conceptual and mathematical model of this process based on a class of item-response theory models. It is demonstrated that this model provides a better fit to three sets of data than does the multinomial processing tree model of redintegration (Schweickert, 1993) and that a number of conceptual accounts of serial recall can be related to the parameters of the model.

Proprioceptive bimanual test in intrinsic and extrinsic coordinates.

PubMed

Iandolo, Riccardo; Squeri, Valentina; De Santis, Dalia; Giannoni, Psiche; Morasso, Pietro; Casadio, Maura

2015-01-01

Is there any difference between matching the position of the hands by asking the subjects to move them to the same spatial location or to mirror-symmetric locations with respect to the body midline? If the motion of the hands were planned in the extrinsic space, the mirror-symmetric task would imply an additional challenge, because we would need to flip the coordinates of the target on the other side of the workspace. Conversely, if the planning were done in intrinsic coordinates, in order to move both hands to the same spot in the workspace, we should compute different joint angles for each arm. Even if both representations were available to the subjects, the two tasks might lead to different results, providing some cue on the organization of the "body schema". In order to answer such questions, the middle fingertip of the non-dominant hand of a population of healthy subjects was passively moved by a manipulandum to 20 different target locations. Subjects matched these positions with the middle fingertip of their dominant hand. For most subjects, the matching accuracy was higher in the extrinsic modality both in terms of systematic error and variability, even for the target locations in which the configuration of the arms was the same for both modalities. This suggests that the matching performance of the subjects could be determined not only by proprioceptive information but also by the cognitive representation of the task: expressing the goal as reaching for the physical location of the hand in space is apparently more effective than requiring to match the proprioceptive representation of joint angles.

Neurons in primary motor cortex engaged during action observation.

PubMed

Dushanova, Juliana; Donoghue, John

2010-01-01

Neurons in higher cortical areas appear to become active during action observation, either by mirroring observed actions (termed mirror neurons) or by eliciting mental rehearsal of observed motor acts. We report the existence of neurons in the primary motor cortex (M1), an area that is generally considered to initiate and guide movement performance, responding to viewed actions. Multielectrode recordings in monkeys performing or observing a well-learned step-tracking task showed that approximately half of the M1 neurons that were active when monkeys performed the task were also active when they observed the action being performed by a human. These 'view' neurons were spatially intermingled with 'do' neurons, which are active only during movement performance. Simultaneously recorded 'view' neurons comprised two groups: approximately 38% retained the same preferred direction (PD) and timing during performance and viewing, and the remainder (62%) changed their PDs and time lag during viewing as compared with performance. Nevertheless, population activity during viewing was sufficient to predict the direction and trajectory of viewed movements as action unfolded, although less accurately than during performance. 'View' neurons became less active and contained poorer representations of action when only subcomponents of the task were being viewed. M1 'view' neurons thus appear to reflect aspects of a learned movement when observed in others, and form part of a broadly engaged set of cortical areas routinely responding to learned behaviors. These findings suggest that viewing a learned action elicits replay of aspects of M1 activity needed to perform the observed action, and could additionally reflect processing related to understanding, learning or mentally rehearsing action.

Motion tracking and electromyography assist the removal of mirror hand contributions to fNIRS images acquired during a finger tapping task performed by children with cerebral palsy

NASA Astrophysics Data System (ADS)

Hervey, Nathan; Khan, Bilal; Shagman, Laura; Tian, Fenghua; Delgado, Mauricio R.; Tulchin-Francis, Kirsten; Shierk, Angela; Smith, Linsley; Reid, Dahlia; Clegg, Nancy J.; Liu, Hanli; MacFarlane, Duncan; Alexandrakis, George

2013-03-01

Functional neurological imaging has been shown to be valuable in evaluating brain plasticity in children with cerebral palsy (CP). In recent studies it has been demonstrated that functional near-infrared spectroscopy (fNIRS) is a viable and sensitive method for imaging motor cortex activities in children with CP. However, during unilateral finger tapping tasks children with CP often exhibit mirror motions (unintended motions in the non-tapping hand), and current fNIRS image formation techniques do not account for this. Therefore, the resulting fNIRS images contain activation from intended and unintended motions. In this study, cortical activity was mapped with fNIRS on four children with CP and five controls during a finger tapping task. Finger motion and arm muscle activation were concurrently measured using motion tracking cameras and electromyography (EMG). Subject-specific regressors were created from motion capture and EMG data and used in a general linear model (GLM) analysis in an attempt to create fNIRS images representative of different motions. The analysis provided an fNIRS image representing activation due to motion and muscle activity for each hand. This method could prove to be valuable in monitoring brain plasticity in children with CP by providing more consistent images between measurements. Additionally, muscle effort versus cortical effort was compared between control and CP subjects. More cortical effort was required to produce similar muscle effort in children with CP. It is possible this metric could be a valuable diagnostic tool in determining response to treatment.

Combining afferent stimulation and mirror therapy for rehabilitating motor function, motor control, ambulation, and daily functions after stroke.

PubMed

Lin, Keh-chung; Huang, Pai-chuan; Chen, Yu-ting; Wu, Ching-yi; Huang, Wen-ling

2014-02-01

Mirror therapy (MT) and mesh glove (MG) afferent stimulation may be effective in reducing motor impairment after stroke. A hybrid intervention of MT combined with MG (MT + MG) may broaden aspects of treatment benefits. To demonstrate the comparative effects of MG + MT, MT, and a control treatment (CT) on the outcomes of motor impairments, manual dexterity, ambulation function, motor control, and daily function. Forty-three chronic stroke patients with mild to moderate upper extremity impairment were randomly assigned to receive MT + MG, MT, or CT for 1.5 hours/day, 5 days/week for 4 weeks. Outcome measures were the Fugl-Meyer Assessment (FMA) and muscle tone measured by Myoton-3 for motor impairment and the Box and Block Test (BBT) and 10-Meter Walk Test (10 MWT) for motor function. Secondary outcomes included kinematic parameters for motor control and the Motor Activity Log and ABILHAND Questionnaire for daily function. FMA total scores were significantly higher and synergistic shoulder abduction during reach was less in the MT + MG and MT groups compared with the CT group. Performance on the BBT and the 10 MWT (velocity and stride length in self-paced task and velocity in as-quickly-as-possible task) were improved after MT + MG compared with MT. MT + MG improved manual dexterity and ambulation. MT + MG and MT reduced motor impairment and synergistic shoulder abduction more than CT. Future studies may integrate functional task practice into treatments to enhance functional outcomes in patients with various levels of motor severity. The long-term effects of MG + MT remain to be evaluated.

A PSD (position sensing device) to map the shift and tilt of the SRT secondary mirror

NASA Astrophysics Data System (ADS)

Pisanu, Tonino; Buffa, Franco; Concu, Raimondo; Marongiu, Pasqualino; Pili, Mauro; Poppi, Sergio; Serra, Giampaolo; Urru, Enrico; Vargiu, Gianpaolo

2014-07-01

The Sardinia Radio Telescope (SRT) Metrology team has started to install the initial group of devices on the new 64 meters radio-telescope. These devices will be devoted for the realization of the antenna deformation control system: an electronic inclinometer able to monitor the alidade deformations and a Position Sensing Device (PSD) able to map the secondary mirror (M2) displacements and tilts. The inclinometer is used to map the rail conditions, the azimuthal axis inclination and the thermal effects on the alidade structure. The PSD will be used to measure the secondary mirror displacements induced by the gravity and by the thermal deformations that produce shifts and tilts with respect to it s ideal optical alignment. The PSD will be traced by a laser diode installed on a mechanically stable position inside the vertex room. Preliminarly we decided to characterize excursion range of M2, in order to know if the PSD measuring range of about +/- 10 mm is enough for our purposes. We designed, built and tested an optical measuring device, based on commercial CMOS with a wider measurement range of +/- 40 mm and with a resolution of around 0.1 mm. After a laboratory characterization at the 23 meters real distance, the PSD and the laser have been installed in the antenna. In this paper we show the results of the measurements performed by moving the antenna in elevation.

Geometric & radiometric vignetting associated with a 72-facet, off-axis, polygon mirror for swept source optical coherence tomography (SS-OCT)

NASA Astrophysics Data System (ADS)

Everson, Michael; Duma, Virgil-Florin; Dobre, George

2017-01-01

Optical Coherence Tomography (OCT) has a broad range of applications in 2D and volumetric imaging of micron scale structures typically used on inaccessible objects such as the retina of the eye. This report focuses on Swept Source OCT (SS-OCT), favoured for its faster scanning speeds and therefore faster data acquisition (highly favourable when imaging live patients). SS-OCT relies on the scanning of a narrow laser line at speeds typically in excess of 100 kHz. We have employed ZemaxTM ray tracing software to simulate one method of splitting the spectrum of a broadband, near-infrared source, into its component wavelengths by reflecting the spectrum from an off-axis, 72-facet polygon mirror at a frequency of 48 kHz. We specifically addressed the geometric and radiometric vignetting associated with the reflected spectrum off an individual mirrored facet and how this may impose limitations to the incident beam size and hence lead to a loss in the power available from the source. It was found that for certain configurations up to 44% of the light was lost at the edges of the spectrum due to both radiometric and geometric vignetting, which may result in an effective swept range of <50 nm from an initial bandwidth of 100 nm. Our simulations account for real refractive errors and losses in the beam caused by lens aberrations, and produce a model of the sampling function of wavelength against time.

Repurposing the Caltech Robinson Hall Coelostat

NASA Astrophysics Data System (ADS)

Treffers, Richard R.; Loisos, G.; Ubbelohde, M.; Douglas, S.; Martinez, M.

2013-01-01

We describe the repurposing of the historic coelostat atop Caltech’s Robinson Hall for building lighting, public education and scientific research. The coelostat was originally part of George Ellery Hale’s vision of the Astrophysical Laboratory on the Caltech campus in 1932. The coelostat, designed by Russell Porter, has a 36 inch diameter primary mirror a 30 inch diameter secondary mirror and provides a 24 inch un-vignetted beam of sunlight into the building. Although constructed in the 1930s, due to wartime pressures and other projects, it was used only briefly in the 1970s and never fully realized. Recently Robinson Hall has been fully renovated to house the Ronald and Maxine Linde Center for Global Environmental Science. The coelostat operation was modernized replacing the old motors and automating all the motions. Each morning, if the weather cooperates, the dome slit opens, the mirrors configured and sunlight pours into the building. The beam of sunlight is divided into three parts. One part goes into a refracting telescope which projects a ten inch diameter of the sun onto a ground glass screen visible to the public. A second fraction is distributed to fiber optic fixtures that illuminate some of the basement rooms. The final fraction goes into two laboratories where it is used in experiments monitoring trace constituents of our atmosphere and for solar catalysis experiments. The instrument as originally conceived required at least two human operators. Now it is fully automatic and doing real science

A new optical head tracing reflected light for nanoprofiler

NASA Astrophysics Data System (ADS)

Okuda, K.; Okita, K.; Tokuta, Y.; Kitayama, T.; Nakano, M.; Kudo, R.; Yamamura, K.; Endo, K.

2014-09-01

High accuracy optical elements are applied in various fields. For example, ultraprecise aspherical mirrors are necessary for developing third-generation synchrotron radiation and XFEL (X-ray Free Electron LASER) sources. In order to make such high accuracy optical elements, it is necessary to realize the measurement of aspherical mirrors with high accuracy. But there has been no measurement method which simultaneously achieves these demands yet. So, we develop the nanoprofiler that can directly measure the any surfaces figures with high accuracy. The nanoprofiler gets the normal vector and the coordinate of a measurement point with using LASER and the QPD (Quadrant Photo Diode) as a detector. And, from the normal vectors and their coordinates, the three-dimensional figure is calculated. In order to measure the figure, the nanoprofiler controls its five motion axis numerically to make the reflected light enter to the QPD's center. The control is based on the sample's design formula. We measured a concave spherical mirror with a radius of curvature of 400 mm by the deflection method which calculates the figure error from QPD's output, and compared the results with those using a Fizeau interferometer. The profile was consistent within the range of system error. The deflection method can't neglect the error caused from the QPD's spatial irregularity of sensitivity. In order to improve it, we have contrived the zero method which moves the QPD by the piezoelectric motion stage and calculates the figure error from the displacement.

The Effect of Time on Word Learning: An Examination of Decay of the Memory Trace and Vocal Rehearsal in Children with and without Specific Language Impairment

ERIC Educational Resources Information Center

Alt, Mary; Spaulding, Tammie

2011-01-01

Purpose: The purpose of this study was to measure the effect of time to response in a fast-mapping word learning task for children with specific language impairment (SLI) and children with typically developing language skills (TD). Manipulating time to response allows us to examine decay of the memory trace, the use of vocal rehearsal, and their…

Interfering with the neural activity of mirror-related frontal areas impairs mentalistic inferences.

PubMed

Herbet, Guillaume; Lafargue, Gilles; Moritz-Gasser, Sylvie; Bonnetblanc, François; Duffau, Hugues

2015-07-01

According to recently proposed interactive dual-process theories, mentalizing abilities emerge from the coherent interaction between two physically distinct neural systems: (1) the mirror network, coding for the low-level embodied representations involved in pre-reflective sociocognitive processes and (2) the mentalizing network per se, which codes for higher level representations subtending the reflective attribution of psychological states. However, although the latest studies have shown that the core areas forming these two neurocognitive systems do indeed maintain effective connectivity during mentalizing, it is unclear whether an intact mirror system (and, more specifically, its anterior node, namely the posterior inferior frontal cortex) is a prerequisite for accurate mentalistic inferences. Intraoperative brain mapping via direct electrical stimulation offers a unique opportunity to address this issue. Electrical stimulation of the brain creates a "virtual" lesion, which provides functional information on well-defined parts of the cerebral cortex. In the present study, five patients were mapped in real time while they performed a mentalizing task. We found six responsive sites: four in the lateral part of the right pars opercularis and two in the dorsal part of the right pars triangularis. On the subcortical level, two additional sites were located within the white matter connectivity of the pars opercularis. Taken as a whole, our results suggest that the right inferior frontal cortex and its underlying axonal connectivity have a key role in mentalizing. Specifically, our findings support the hypothesis whereby transient, functional disruption of the mirror network influences higher order mentalistic inferences.

Clutter in electronic medical records: examining its performance and attentional costs using eye tracking.

PubMed

Moacdieh, Nadine; Sarter, Nadine

2015-06-01

The objective was to use eye tracking to trace the underlying changes in attention allocation associated with the performance effects of clutter, stress, and task difficulty in visual search and noticing tasks. Clutter can degrade performance in complex domains, yet more needs to be known about the associated changes in attention allocation, particularly in the presence of stress and for different tasks. Frequently used and relatively simple eye tracking metrics do not effectively capture the various effects of clutter, which is critical for comprehensively analyzing clutter and developing targeted, real-time countermeasures. Electronic medical records (EMRs) were chosen as the application domain for this research. Clutter, stress, and task difficulty were manipulated, and physicians' performance on search and noticing tasks was recorded. Several eye tracking metrics were used to trace attention allocation throughout those tasks, and subjective data were gathered via a debriefing questionnaire. Clutter degraded performance in terms of response time and noticing accuracy. These decrements were largely accentuated by high stress and task difficulty. Eye tracking revealed the underlying attentional mechanisms, and several display-independent metrics were shown to be significant indicators of the effects of clutter. Eye tracking provides a promising means to understand in detail (offline) and prevent (in real time) major performance breakdowns due to clutter. Display designers need to be aware of the risks of clutter in EMRs and other complex displays and can use the identified eye tracking metrics to evaluate and/or adjust their display. © 2015, Human Factors and Ergonomics Society.

Minimising back reflections from the common path objective in a fundus camera

NASA Astrophysics Data System (ADS)

Swat, A.

2016-11-01

Eliminating back reflections is critical in the design of a fundus camera with internal illuminating system. As there is very little light reflected from the retina, even excellent antireflective coatings are not sufficient suppression of ghost reflections, therefore the number of surfaces in the common optics in illuminating and imaging paths shall be minimised. Typically a single aspheric objective is used. In the paper an alternative approach, an objective with all spherical surfaces, is presented. As more surfaces are required, more sophisticated method is needed to get rid of back reflections. Typically back reflections analysis, comprise treating subsequent objective surfaces as mirrors, and reflections from the objective surfaces are traced back through the imaging path. This approach can be applied in both sequential and nonsequential ray tracing. It is good enough for system check but not very suitable for early optimisation process in the optical system design phase. There are also available standard ghost control merit function operands in the sequential ray-trace, for example in Zemax system, but these don't allow back ray-trace in an alternative optical path, illumination vs. imaging. What is proposed in the paper, is a complete method to incorporate ghost reflected energy into the raytracing system merit function for sequential mode which is more efficient in optimisation process. Although developed for the purpose of specific case of fundus camera, the method might be utilised in a wider range of applications where ghost control is critical.

Procedural errors in air traffic control: effects of traffic density, expertise, and automation.

PubMed

Di Nocera, Francesco; Fabrizi, Roberto; Terenzi, Michela; Ferlazzo, Fabio

2006-06-01

Air traffic management requires operators to frequently shift between multiple tasks and/or goals with different levels of accomplishment. Procedural errors can occur when a controller accomplishes one of the tasks before the entire operation has been completed. The present study had two goals: first, to verify the occurrence of post-completion errors in air traffic control (ATC) tasks; and second, to assess effects on performance of medium term conflict detection (MTCD) tools. There were 18 military controllers who performed a simulated ATC task with and without automation support (MTCD vs. manual) in high and low air traffic density conditions. During the task, which consisted of managing several simulated flights in an enroute ATC scenario, a trace suddenly disappeared "after" the operator took the aircraft in charge, "during" the management of the trace, or "before" the pilot's first contact. In the manual condition, only the fault type "during" was found to be significantly different from the other two. On the contrary, when in the MTCD condition, the fault type "after" generated significantly less errors than the fault type "before." Additionally, automation was found to affect performance of junior controllers, whereas seniors' performance was not affected. Procedural errors can happen in ATC, but automation can mitigate this effect. Lack of benefits for the "before" fault type may be due to the fact that operators extend their reliance to a part of the task that is unsupported by the automated system.

Procedural Learning in Children With Developmental Coordination, Reading, and Attention Disorders.

PubMed

Magallón, Sara; Crespo-Eguílaz, Nerea; Narbona, Juan

2015-10-01

The aim is to assess repetition-based learning of procedures in children with developmental coordination disorder (DCD), reading disorder (RD) and attention-deficit hyperactivity disorder (ADHD). Participants included 187 children, studied in 4 groups: (a) DCD comorbid with RD and ADHD (DCD+RD+ADHD) (n = 30); (b) RD comorbid with ADHD (RD+ADHD) (n = 48); (c) ADHD (n = 19); and typically developing children (control group) (n = 90). Two procedural learning tasks were used: Assembly learning and Mirror drawing. Children were tested on 4 occasions for each task: 3 trials were consecutive and the fourth trial was performed after an interference task. Task performance by DCD+RD+ADHD children improved with training (P < .05); however, the improvement was significantly lower than that achieved by the other groups (RD+ADHD, ADHD and controls) (P < .05). In conclusion, children with DCD+RD+ADHD improve in their use of cognitive-motor procedures over a short training period. Aims of intervention in DCD+RD+ADHD should be based on individual learning abilities. © The Author(s) 2015.

Advanced Hybrid Particulate Collector Project Management Plan

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

Miller, S.J.

As the consumption of energy increases, its impact on ambient air quality has become a significant concern. Recent studies indicate that fine particles from coal combustion cause health problems as well as atmospheric visibility impairment. These problems are further compounded by the concentration of hazardous trace elements such as mercury, cadmium, selenium, and arsenic in fine particles. Therefore, a current need exists to develop superior, but economical, methods to control emissions of fine particles. Since most of the toxic metals present in coal will be in particulate form, a high level of fine- particle collection appears to be the bestmore » method of overall air toxics control. However, over 50% of mercury and a portion of selenium emissions are in vapor form and cannot be collected in particulate control devices. Therefore, this project will focus on developing technology not only to provide ultrahigh collection efficiency of particulate air toxic emissions, but also to capture vapor- phase trace metals such as mercury and selenium. Currently, the primary state-of-the-art technologies for particulate control are fabric filters (baghouses) and electrostatic precipitators (ESPs). However, they both have limitations that prevent them from achieving ultrahigh collection of fine particulate matter and vapor-phase trace metals. The objective of this project is to develop a highly reliable advanced hybrid particulate collector (AHPC) that can provide > 99.99 % particulate collection efficiency for all particle sizes between 0.01 and 50 14m, is applicable for use with all U.S. coals, and is cost-0443competitive with existing technologies. Phase I of the project is organized into three tasks: Task I - Project Management, Reporting, and Subcontract Consulting Task 2 - Modeling, Design, and Construction of 200-acfm AHPC Model Task 3 - Experimental Testing and Subcontract Consulting« less

Dynamic Load Balancing Based on Constrained K-D Tree Decomposition for Parallel Particle Tracing

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

Zhang, Jiang; Guo, Hanqi; Yuan, Xiaoru

Particle tracing is a fundamental technique in flow field data visualization. In this work, we present a novel dynamic load balancing method for parallel particle tracing. Specifically, we employ a constrained k-d tree decomposition approach to dynamically redistribute tasks among processes. Each process is initially assigned a regularly partitioned block along with duplicated ghost layer under the memory limit. During particle tracing, the k-d tree decomposition is dynamically performed by constraining the cutting planes in the overlap range of duplicated data. This ensures that each process is reassigned particles as even as possible, and on the other hand the newmore » assigned particles for a process always locate in its block. Result shows good load balance and high efficiency of our method.« less

Complex Systems and Human Performance Modeling

DTIC Science & Technology

2013-12-01

human communication patterns can be implemented in a task network modeling tool. Although queues are a basic feature in many task network modeling...time. MODELING COMMUNICATIVE BEHAVIOR Barabasi (2010) argues that human communication patterns are “bursty”; that is, the inter-event arrival...Having implemented the methods advocated by Clauset et al. in C3TRACE, we have grown more confident that the human communication data discussed above

Rightward biases in free-viewing visual bisection tasks: implications for leftward responses biases on similar tasks.

PubMed

Elias, Lorin J; Robinson, Brent; Saucier, Deborah M

2005-12-01

Neurologically normal individuals exhibit strong leftward response biases during free-viewing perceptual judgments of brightness, quantity, and size. When participants view two mirror-reversed objects and they are forced to choose which object appears darker, more numerous, or larger, the stimulus with the relevant feature on the left side is chosen 60-75% of the time. This effect could be influenced by inaccurate judgments of the true centre-point of the objects being compared. In order to test this possibility, 10 participants completed three visual bisection tasks on stimuli known to elicit strong leftward response biases. Participants were monitored using a remote eye-tracking device and instructed to stare at the subjective midpoint of objects presented on a computer screen. Although it was predicted that bisection errors would deviate to the left of centre (as is the case in the line bisection literature), the opposite effect was found. Significant rightward bisection errors were evident on two of the three tasks, and the leftward biases seen during forced-choice tasks could be the result of misjudgments to the right of centre on these same tasks.

Simulating x-ray telescopes with McXtrace: a case study of ATHENA's optics

NASA Astrophysics Data System (ADS)

Ferreira, Desiree D. M.; Knudsen, Erik B.; Westergaard, Niels J.; Christensen, Finn E.; Massahi, Sonny; Shortt, Brian; Spiga, Daniele; Solstad, Mathias; Lefmann, Kim

2016-07-01

We use the X-ray ray-tracing package McXtrace to simulate the performance of X-ray telescopes based on Silicon Pore Optics (SPO) technologies. We use as reference the design of the optics of the planned X-ray mission Advanced Telescope for High ENergy Astrophysics (ATHENA) which is designed as a single X-ray telescope populated with stacked SPO substrates forming mirror modules to focus X-ray photons. We show that is possible to simulate in detail the SPO pores and qualify the use of McXtrace for in-depth analysis of in-orbit performance and laboratory X-ray test results.

Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers

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

Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto

2006-12-10

To develop x-ray mirrors for micropore optics, smooth silicon (111)sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 {mu}m wide (111) sidewalls was fabricated using a 220 {mu}m thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time,x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements.

Accurate Simulation of Parametrically Excited Micromirrors via Direct Computation of the Electrostatic Stiffness

PubMed Central

Frangi, Attilio; Guerrieri, Andrea; Boni, Nicoló

2017-01-01

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches of the mirror response, we implement a simplified continuation method with arc-length control and propose an innovative technique based on Finite Elements and the concepts of material derivative in order to compute the electrostatic stiffness; i.e., the derivative of the torque with respect to the torsional angle, as required by the continuation approach. PMID:28383483

Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers.

PubMed

Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto; Mitsuda, Kazuhisa; Hoshino, Akio; Ishisaki, Yoshitaka; Yang, Zhen; Takano, Takayuki; Maeda, Ryutaro

2006-12-10

To develop x-ray mirrors for micropore optics, smooth silicon (111) sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 microm wide (111) sidewalls was fabricated using a 220 microm thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time, x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements.

The history of neurosurgical treatment of sports concussion.

PubMed

Stone, James L; Patel, Vimal; Bailes, Julian E

2014-10-01

Concussion has a long and interesting history spanning at least the 5 millennia of written medical record and closely mirrors the development of surgery and neurosurgery. Not surprisingly, much of the past and present experimental head injury and concussion work has been performed within neurosurgically driven laboratories or by several surgically oriented neurologists. This historical review chronicles the key aspects of neurosurgical involvement in sports concussion as related to the diagnosis, treatment, mitigation, and prevention of injury using the example of American football. In addition, we briefly trace the developments that led to our current understanding of the biomechanical and neurophysiological basis of concussion.

Set this house on fire: the self-analysis of Raymond Carver.

PubMed

Tutter, Adele

2011-10-01

The convergence of features of Raymond Carver's short-story oeuvre and of psychoanalytic methodology suggests that Carver's writing served as the fulcrum and focus of a self-analytic experience. Within this model, his stories function as container and mirror of myriad aspects of the writer's self. Tracing the developmental arc of the contextual meanings of one motif--fire--through six stories and their ur-texts demonstrates gains comparable to certain analytic goals, including enhanced integration, accountability, and self-awareness. Over time, Carver's narratives of rage, impotence, and despair give way to a new story: of mourning, forgiveness, and the rekindling of hope.

Accurate Simulation of Parametrically Excited Micromirrors via Direct Computation of the Electrostatic Stiffness.

PubMed

Frangi, Attilio; Guerrieri, Andrea; Boni, Nicoló

2017-04-06

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches of the mirror response, we implement a simplified continuation method with arc-length control and propose an innovative technique based on Finite Elements and the concepts of material derivative in order to compute the electrostatic stiffness; i.e., the derivative of the torque with respect to the torsional angle, as required by the continuation approach.

Time-based loss in visual short-term memory is from trace decay, not temporal distinctiveness.

PubMed

Ricker, Timothy J; Spiegel, Lauren R; Cowan, Nelson

2014-11-01

There is no consensus as to why forgetting occurs in short-term memory tasks. In past work, we have shown that forgetting occurs with the passage of time, but there are 2 classes of theories that can explain this effect. In the present work, we investigate the reason for time-based forgetting by contrasting the predictions of temporal distinctiveness and trace decay in the procedure in which we have observed such loss, involving memory for arrays of characters or letters across several seconds. The 1st theory, temporal distinctiveness, predicts that increasing the amount of time between trials will lead to less proactive interference, resulting in less forgetting across a retention interval. In the 2nd theory, trace decay, temporal distinctiveness between trials is irrelevant to the loss over a retention interval. Using visual array change detection tasks in 4 experiments, we find small proactive interference effects on performance under some specific conditions, but no concomitant change in the effect of a retention interval. We conclude that trace decay is the more suitable class of explanations of the time-based forgetting in short-term memory that we have observed, and we suggest the need for further clarity in what the exact basis of that decay may be. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Development and Operations of the Astrophysics Data System

NASA Technical Reports Server (NTRS)

Murray, Stephen S.; Oliversen, Ronald (Technical Monitor)

2003-01-01

SAO TASKS ACCOMPLISHED: Abstract Service: (1) Continued regular updates of abstracts in the databases, both at SAO and at all mirror sites; (2) Established a new naming convention of QB books in preparation for adding physics books from Hollis or Library of Congress; (3) Modified handling of object tag so as not to interfere with XHTML definition; (4) Worked on moving 'what's new' announcements to a majordomo email list so as not to interfere with divisional mail handling; (5) Implemented and tested new first author feature following suggestions from users at the AAS meeting; (6) Added SSRv entries back to volume 1 in preparation for scanning of the journal; (7) Assisted in the re-configuration of the ADS mirror site at the CDS and sent a new set of tapes containing article data to allow re-creation of the ADS article data lost during the move; (8) Created scripts to automatically download Astrobiology.

Utility of multi-channel surface electromyography in assessment of focal hand dystonia.

PubMed

Sivadasan, Ajith; Sanjay, M; Alexander, Mathew; Devasahayam, Suresh R; Srinivasa, Babu K

2013-09-01

Surface electromyography (SEMG) allows objective assessment and guides selection of appropriate treatment in focal hand dystonia (FHD). Sixteen-channel SEMG obtained during different phases of a writing task was used to study timing, activation patterns, and spread of muscle contractions in FHD compared with normal controls. Customized software was developed to acquire and analyze EMG signals. SEMG of FHD subjects (20) showed "early onset" during motor imagery, rapid proximal muscle recruitment, agonist-antagonist co-contraction involving proximal muscle groups, "delayed offset" after stopping writing, higher rectified mean amplitudes, and mirror activity in contralateral limb compared with controls (16). Muscle activation latencies were heterogenous in FHD. Anticipation, delayed relaxation, and mirror EMG activation were noted in FHD. A clear pattern of muscle activation cannot be ascertained. Multi-channel SEMG can aid in objective assessment of temporal-spatial distribution of activity and can refine targeted therapies like chemodenervation and biofeedback. Copyright © 2013 Wiley Periodicals, Inc.

Seeing the partner: a video recall study of emotional behavior in same- and mixed-sex late adolescent romantic couples.

PubMed

Darling, Nancy; Clarke, Sara A

2009-08-01

Fifty-three college-aged same- and mixed-sex romantic couples (83% White, 63% female, mean age, 20.8) engaged in a video recall task in which they rated their own and their partners' behaviors and emotions. Females reported feeling more connected to partners and reported fewer negative behaviors than males. Females with male partners reported the highest feelings of connection and the fewest negative behaviors. Males with male partners reported the lowest connection and most negative behaviors. Behavioral mirroring and empathic accuracy did not vary by sex of the actor or of their partner. Partners' self-reported connection and negative behaviors were similar and they accurately perceived each others' average behavioral and emotional states. The data showed little evidence that partners' behaviors mirrored one another temporally across time segments, however. Results suggest that college-aged same and mixed-sex romantic couples show greater similarities than differences in functioning.

Combining freeform optics and curved detectors for wide field imaging: a polynomial approach over squared aperture.

PubMed

Muslimov, Eduard; Hugot, Emmanuel; Jahn, Wilfried; Vives, Sebastien; Ferrari, Marc; Chambion, Bertrand; Henry, David; Gaschet, Christophe

2017-06-26

In the recent years a significant progress was achieved in the field of design and fabrication of optical systems based on freeform optical surfaces. They provide a possibility to build fast, wide-angle and high-resolution systems, which are very compact and free of obscuration. However, the field of freeform surfaces design techniques still remains underexplored. In the present paper we use the mathematical apparatus of orthogonal polynomials defined over a square aperture, which was developed before for the tasks of wavefront reconstruction, to describe shape of a mirror surface. Two cases, namely Legendre polynomials and generalization of the Zernike polynomials on a square, are considered. The potential advantages of these polynomials sets are demonstrated on example of a three-mirror unobscured telescope with F/# = 2.5 and FoV = 7.2x7.2°. In addition, we discuss possibility of use of curved detectors in such a design.

Power changes how the brain responds to others.

PubMed

Hogeveen, Jeremy; Inzlicht, Michael; Obhi, Sukhvinder S

2014-04-01

Power dynamics are a ubiquitous feature of human social life, yet little is known about how power is implemented in the brain. Motor resonance is the activation of similar brain networks when acting and when watching someone else act, and is thought to be implemented, in part, by the human mirror system. We investigated the effects of power on motor resonance during an action observation task. Separate groups of participants underwent a high-, neutral, or low-power induction priming procedure, prior to observing the actions of another person. During observation, motor resonance was determined with transcranial magnetic stimulation (TMS) via measures of motor cortical output. High-power participants demonstrated lower levels of resonance than low-power participants, suggesting reduced mirroring of other people in those with power. These differences suggest that decreased motor resonance to others' actions might be one of the neural mechanisms underlying power-induced asymmetries in processing our social interaction partners.

Shifting attention across near and far spaces: implications for the use of hands-free cell phones while driving.

PubMed

Ferlazzo, Fabio; Fagioli, Sabrina; Di Nocera, Francesco; Sdoia, Stefano

2008-11-01

In three experiments, participants performed two tasks concurrently during driving. In the peripheral detection task, they responded manually to visual stimuli delivered through a LED placed on the internal rear mirror; in the conversation task, they were engaged in a conversation with a passenger, or through earphone-operated, loudspeaker-operated, or hand-held cell phones. Results showed that drivers were slower at responding to the visual stimuli when conversing through a hand-held cell phone or an earphone-operated cell phone than when conversing through a loudspeaker-operated cell phone or with a passenger. These results suggest that due to the brain coding the space into multiple representations, devices that make phone conversations taking place in the near, personal space make drivers slower at responding to visual stimuli, compared to devices that make the conversation occurring in a far space.

Dysfunctions in brain networks supporting empathy: An fMRI study in adults with autism spectrum disorders

PubMed Central

Schulte-Rüther, Martin; Greimel, Ellen; Markowitsch, Hans J.; Kamp-Becker, Inge; Remschmidt, Helmut; Fink, Gereon R.; Piefke, Martina

2010-01-01

The present study aimed at identifying dysfunctions in brain networks that may underlie disturbed empathic behavior in autism spectrum disorders (ASD). During functional magnetic resonance imaging, subjects were asked to identify the emotional state observed in a facial stimulus (other-task) or to evaluate their own emotional response (self-task). Behaviorally, ASD subjects performed equally to the control group during the other-task, but showed less emotionally congruent responses in the self-task. Activations in brain regions related to theory of mind were observed in both groups. Activations of the medial prefrontal cortex (MPFC) were located in dorsal subregions in ASD subjects and in ventral areas in control subjects. During the self-task, ASD subjects activated an additional network of frontal and inferior temporal areas. Frontal areas previously associated with the human mirror system were activated in both tasks in control subjects, while ASD subjects recruited these areas during the self-task only. Activations in the ventral MPFC may provide the basis for one's “emotional bond” with other persons’ emotions. Such atypical patterns of activation may underlie disturbed empathy in individuals with ASD. Subjects with ASD may use an atypical cognitive strategy to gain access to their own emotional state in response to other people's emotions. PMID:20945256

Dysfunctions in brain networks supporting empathy: an fMRI study in adults with autism spectrum disorders.

PubMed

Schulte-Rüther, Martin; Greimel, Ellen; Markowitsch, Hans J; Kamp-Becker, Inge; Remschmidt, Helmut; Fink, Gereon R; Piefke, Martina

2011-01-01

The present study aimed at identifying dysfunctions in brain networks that may underlie disturbed empathic behavior in autism spectrum disorders (ASD). During functional magnetic resonance imaging, subjects were asked to identify the emotional state observed in a facial stimulus (other-task) or to evaluate their own emotional response (self-task). Behaviorally, ASD subjects performed equally to the control group during the other-task, but showed less emotionally congruent responses in the self-task. Activations in brain regions related to theory of mind were observed in both groups. Activations of the medial prefrontal cortex (MPFC) were located in dorsal subregions in ASD subjects and in ventral areas in control subjects. During the self-task, ASD subjects activated an additional network of frontal and inferior temporal areas. Frontal areas previously associated with the human mirror system were activated in both tasks in control subjects, while ASD subjects recruited these areas during the self-task only. Activations in the ventral MPFC may provide the basis for one's "emotional bond" with other persons' emotions. Such atypical patterns of activation may underlie disturbed empathy in individuals with ASD. Subjects with ASD may use an atypical cognitive strategy to gain access to their own emotional state in response to other people's emotions.

On improved confinement in mirror plasmas by a radial electric field

NASA Astrophysics Data System (ADS)

Ågren, O.; Moiseenko, V. E.

2017-11-01

A weak radial electric field can suppress radial excursions of a guiding center from its mean magnetic surface. The physical origin of this effect is the smearing action by a poloidal E × B rotation, which tend to cancel out the inward and outward radial drifts. A use of this phenomenon may provide larger margins for magnetic field shaping with radial confinement of particles maintained in the collision free idealization. Mirror fields, stabilized by a quadrupolar field component, are of particular interest for their MHD stability and the possibility to control the quasi neutral radial electric field by biased potential plates outside the confinement region. Flux surface footprints on the end tank wall have to be traced to avoid short-circuiting between biased plates. Assuming a robust biasing procedure, moderate voltage demands for the biased plates seems adequate to cure even the radial excursions of Yushmanov ions which could be locally trapped near the mirrors. Analytical expressions are obtained for a magnetic quadrupolar mirror configuration which possesses minimal radial magnetic drifts in the central confinement region. By adding a weak controlled radial quasi-neutral electric field, the majority of gyro centers are predicted to be forced to move even closer to their respective mean magnetic surface. The gyro center radial coordinate is in such a case an accurate approximation for a constant of motion. By using this constant of motion, the analysis is in a Vlasov description extended to finite β. A correspondence between that Vlasov system and a fluid description with a scalar pressure and an electric potential is verified. The minimum B criterion is considered and implications for flute mode stability in the considered magnetic field is analyzed. By carrying out a long-thin expansion to a higher order, the validity of the calculations are extended to shorter and more compact device designs.

Motor skills in Czech children with attention-deficit/hyperactivity disorder and their neurotypical counterparts.

PubMed

Scharoun, S M; Bryden, P J; Otipkova, Z; Musalek, M; Lejcarova, A

2013-11-01

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed neurobehavioural disorder. Characterized by recurring problems with impulsiveness and inattention in combination with hyperactivity, motor impairments have also been well documented in the literature. The aim of this study was to compare the fine and gross motor skills of male and female children with ADHD and their neurotypical counterparts within seven skill assessments. This included three fine motor tasks: (1) spiral tracing, (2) dot filling, (3) tweezers and beads; and four gross motor tasks: (1) twistbox, (2) foot tapping, (3) small plate finger tapping, and (4) large plate finger tapping. It was hypothesized that children with ADHD would display poorer motor skills in comparison to neurotypical controls in both fine and gross motor assessments. However, statistically significant differences between the groups only emerged in four of the seven tasks (spiral tracing, dot filling, tweezers and beads and foot tapping). In line with previous findings, the complexity underlying upper limb tasks solidified the divide in performance between children with ADHD and their neurotypical counterparts. In light of similar research, impairments in lower limb motor skill were also observed. Future research is required to further delineate trends in motor difficulties in ADHD, while further investigating the underlying mechanisms of impairment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Identifying Oneself with the Face of Someone Else Impairs the Egocentered Visuo-spatial Mechanisms: A New Double Mirror Paradigm to Study Self–other Distinction and Interaction

PubMed Central

Thirioux, Bérangère; Wehrmann, Moritz; Langbour, Nicolas; Jaafari, Nematollah; Berthoz, Alain

2016-01-01

Looking at our face in a mirror is one of the strongest phenomenological experiences of the Self in which we need to identify the face as reflected in the mirror as belonging to us. Recent behavioral and neuroimaging studies reported that self-face identification not only relies upon visual-mnemonic representation of one’s own face but also upon continuous updating and integration of visuo-tactile signals. Therefore, bodily self-consciousness plays a major role in self-face identification, with respect to interplay between unisensory and multisensory processing. However, if previous studies demonstrated that the integration of multisensory body-related signals contributes to the visual processing of one’s own face, there is so far no data regarding how self-face identification, inversely, contributes to bodily self-consciousness. In the present study, we tested whether self–other face identification impacts either the egocentered or heterocentered visuo-spatial mechanisms that are core processes of bodily self-consciousness and sustain self–other distinction. For that, we developed a new paradigm, named “Double Mirror.” This paradigm, consisting of a semi-transparent double mirror and computer-controlled Light Emitting Diodes, elicits self–other face merging illusory effect in ecologically more valid conditions, i.e., when participants are physically facing each other and interacting. Self-face identification was manipulated by exposing pairs of participants to an Interpersonal Visual Stimulation in which the reflection of their faces merged in the mirror. Participants simultaneously performed visuo-spatial and mental own-body transformation tasks centered on their own face (egocentered) or the face of their partner (heterocentered) in the pre- and post-stimulation phase. We show that self–other face identification altered the egocentered visuo-spatial mechanisms. Heterocentered coding was preserved. Our data suggest that changes in self-face identification induced a bottom-up conflict between the current visual representation and the stored mnemonic representation of one’s own face which, in turn, top-down impacted bodily self-consciousness. PMID:27610095

Role of Gaze Cues in Interpersonal Motor Coordination: Towards Higher Affiliation in Human-Robot Interaction.

PubMed

Khoramshahi, Mahdi; Shukla, Ashwini; Raffard, Stéphane; Bardy, Benoît G; Billard, Aude

2016-01-01

The ability to follow one another's gaze plays an important role in our social cognition; especially when we synchronously perform tasks together. We investigate how gaze cues can improve performance in a simple coordination task (i.e., the mirror game), whereby two players mirror each other's hand motions. In this game, each player is either a leader or follower. To study the effect of gaze in a systematic manner, the leader's role is played by a robotic avatar. We contrast two conditions, in which the avatar provides or not explicit gaze cues that indicate the next location of its hand. Specifically, we investigated (a) whether participants are able to exploit these gaze cues to improve their coordination, (b) how gaze cues affect action prediction and temporal coordination, and (c) whether introducing active gaze behavior for avatars makes them more realistic and human-like (from the user point of view). 43 subjects participated in 8 trials of the mirror game. Each subject performed the game in the two conditions (with and without gaze cues). In this within-subject study, the order of the conditions was randomized across participants, and subjective assessment of the avatar's realism was assessed by administering a post-hoc questionnaire. When gaze cues were provided, a quantitative assessment of synchrony between participants and the avatar revealed a significant improvement in subject reaction-time (RT). This confirms our hypothesis that gaze cues improve the follower's ability to predict the avatar's action. An analysis of the pattern of frequency across the two players' hand movements reveals that the gaze cues improve the overall temporal coordination across the two players. Finally, analysis of the subjective evaluations from the questionnaires reveals that, in the presence of gaze cues, participants found it not only more human-like/realistic, but also easier to interact with the avatar. This work confirms that people can exploit gaze cues to predict another person's movements and to better coordinate their motions with their partners, even when the partner is a computer-animated avatar. Moreover, this study contributes further evidence that implementing biological features, here task-relevant gaze cues, enable the humanoid robotic avatar to appear more human-like, and thus increase the user's sense of affiliation.

A Research on the Primary Mirror Manipulator of Large Segmented-mirror Telescope

NASA Astrophysics Data System (ADS)

Zuo, H.

2012-09-01

Since Galileo firstly used the telescope to observe the sky 400 years ago, the aperture of the telescope has become larger and larger to observe the deeper universe, and the segmented-mirror telescope is becoming more and more popular with increasing aperture. In the early 21st century, a series of segmented-mirror telescopes have been constructed including the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) of China. LAMOST is a meridian reflecting Schmidt telescope, and the dimension of the primary mirror is about 6.7 m× 6 m, which is composed of 37 hexagonal sub-mirrors. However, a problem about the mirror installation appears with the increasing aperture. If there are hundreds of sub-mirrors in the telescope, it is a challenging job to mount and dismount them to the truss. This problem is discussed in this paper and a manipulator for the primary mirror of LAMOST is designed to perform the mount and dismount work. In chapter 1, all the segmented-mirror telescopes in the world are introduced and how the sub-mirrors of these telescopes are installed has been investigated. After comparing with the serial and the parallel robot, a serial robot manipulator proposal, which has several redundant degrees of freedom (DOFs), has been chosen from a series of design proposals. In chapter 2, the theoretical analysis has been carried out on the basis of the design proposal, which includes the forward kinematics and the inverse kinematics. Firstly the D-H coordinate is built according to the structure of the manipulator, so it is possible to obtain the end-effector position and orientation from the individual joint motion thanks to the forward kinematics. Because of the redundant DOFs of the manipulator, the inverse kinematics solution can be a very trick task, and the result may not be only, therefore a kind of simulation is carried out to get the numerical solution using ADAMS (Automatic Dynamic Analysis of Mechanical System). In the dynamics analysis the Lagrange formulation is introduced, and the dynamic equations of the manipulator have been obtained by using the Lagrange method. Since the manipulator is a serious coupling system, the dynamic curve of the key joints is plotted by using the ADAMS software. According to the theoretical analysis, the manipulator for the primary mirror of LAMOST is designed and fabricated. The whole manipulator consists of three parts. The first part is the mechanical arm which is used to realize the high speed and the long distance location, and it is rebuilt from a small truck crane; The second part is a serial mechanical hand which is used to realize the low speed and the short distance location. It has six DOFs including the pitch, the rotate about the vertical axis, the elevation along the vertical axis, and two horizontal translations. Subsequently the structure is analyzed in the ANSYS software to confirm that the strength is enough and the displacement is in the tolerance; The third part is a mechanical wrist, in which part a hydraulic rod is used to keep the bottom of the mechanical hand horizontal. In chapter 6, the control characteristics of the whole manipulator are analyzed. Furthermore, the control method and flowchart are proposed. Based on this method the control device was selected. In the end of this paper, the main work and the results of this project are summarized. Further research is prospected and it provides a reference for the future large telescope projects.

Presurgical language fMRI: Mapping of six critical regions

PubMed Central

Walshaw, Patricia D.; Hale, Kayleigh; Gaillard, William D.; Baxter, Leslie C.; Berl, Madison M.; Polczynska, Monika; Noble, Stephanie; Alkawadri, Rafeed; Hirsch, Lawrence J.; Constable, R. Todd; Bookheimer, Susan Y.

2017-01-01

Abstract Language mapping is a key goal in neurosurgical planning. fMRI mapping typically proceeds with a focus on Broca's and Wernicke's areas, although multiple other language‐critical areas are now well‐known. We evaluated whether clinicians could use a novel approach, including clinician‐driven individualized thresholding, to reliably identify six language regions, including Broca's Area, Wernicke's Area (inferior, superior), Exner's Area, Supplementary Speech Area, Angular Gyrus, and Basal Temporal Language Area. We studied 22 epilepsy and tumor patients who received Wada and fMRI (age 36.4[12.5]; Wada language left/right/mixed in 18/3/1). fMRI tasks (two × three tasks) were analyzed by two clinical neuropsychologists who flexibly thresholded and combined these to identify the six regions. The resulting maps were compared to fixed threshold maps. Clinicians generated maps that overlapped significantly, and were highly consistent, when at least one task came from the same set. Cases diverged when clinicians prioritized different language regions or addressed noise differently. Language laterality closely mirrored Wada data (85% accuracy). Activation consistent with all six language regions was consistently identified. In blind review, three external, independent clinicians rated the individualized fMRI language maps as superior to fixed threshold maps; identified the majority of regions significantly more frequently; and judged language laterality to mirror Wada lateralization more often. These data provide initial validation of a novel, clinician‐based approach to localizing language cortex. They also demonstrate clinical fMRI is superior when analyzed by an experienced clinician and that when fMRI data is of low quality judgments of laterality are unreliable and should be withheld. Hum Brain Mapp 38:4239–4255, 2017. © 2017 Wiley Periodicals, Inc. PMID:28544168