Pain relief is associated with decreasing postural sway in patients with non-specific low back pain.

Science.gov (United States)

Ruhe, Alexander; Fejer, René; Walker, Bruce

2012-03-21

Increased postural sway is well documented in patients suffering from non-specific low back pain, whereby a linear relationship between higher pain intensities and increasing postural sway has been described. No investigation has been conducted to evaluate whether this relationship is maintained if pain levels change in adults with non-specific low back pain. Thirty-eight patients with non-specific low back pain and a matching number of healthy controls were enrolled. Postural sway was measured by three identical static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11). The patients received three manual interventions (e.g. manipulation, mobilization or soft tissue techniques) at 3-4 day intervals, postural sway measures were obtained at each occasion. A clinically relevant decrease of four NRS scores in associated with manual interventions correlated with a significant decrease in postural sway. In contrast, if no clinically relevant change in intensity occurred (≤ 1 level), postural sway remained similar compared to baseline. The postural sway measures obtained at follow-up sessions 2 and 3 associated with specific NRS level showed no significant differences compared to reference values for the same pain score. Alterations in self-reported pain intensities are closely related to changes in postural sway. The previously reported linear relationship between the two variables is maintained as pain levels change. Pain interference appears responsible for the altered sway in pain sufferers. This underlines the clinical use of sway measures as an objective monitoring tool during treatment or rehabilitation.

SWAY Bæredygtighed hos SMV'er

DEFF Research Database (Denmark)

2016-01-01

Valg af materiale/medie/form: SWAY der indeholder forskelligt materiale Valg af arbejdsform: Kan anvendes som et element i undervisning eller indlæg Begrundelse for valg af materiale/medie/form/arbejdsform: Forskelligt materiale kan samlet heri og det kan tilgås af alle via linket...

Viewing pain and happy faces elicited similar changes in postural body sway.

Directory of Open Access Journals (Sweden)

Juan Gea

Full Text Available Affective facial expressions are potent social cues that can induce relevant physiological changes, as well as behavioral dispositions in the observer. Previous studies have revealed that angry faces induced significant reductions in body sway as compared with neutral and happy faces, reflecting an avoidance behavioral tendency as freezing. The expression of pain is usually considered an unpleasant stimulus, but also a relevant cue for delivering effective care and social support. Nevertheless, there are few data about behavioral dispositions elicited by the observation of pain expressions in others. The aim of the present research was to evaluate approach-avoidance tendencies by using video recordings of postural body sway when participants were standing and observing facial expressions of pain, happy and neutral. We hypothesized that although pain faces would be rated as more unpleasant than the other faces, they would provoke significant changes in postural body sway as compared to neutral facial expressions. Forty healthy female volunteers (mean age 25 participated in the study. Amplitude of forward movements and backward movements in the anterior-posterior and medial-lateral axes were obtained. Statistical analyses revealed that pain faces were the most unpleasant stimuli, and that both happy and pain faces were more arousing than neutral ones. Happy and pain faces also elicited greater amplitude of body sway in the anterior-posterior axes as compared with neutral faces. In addition, significant positive correlations were found between body sway elicited by pain faces and pleasantness and empathic ratings, suggesting that changes in postural body sway elicited by pain faces might be associated with approach and cooperative behavioral responses.

Is there a relationship between pain intensity and postural sway in patients with non-specific low back pain?

DEFF Research Database (Denmark)

Ruhe, A.; Fejer, R.; Walker, B.

2011-01-01

compared to healthy controls. In addition, regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters. Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were......Background: Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain, whereby the altered postural sway includes both higher mean sway velocities and larger sway area. No investigation has been conducted to evaluate a relationship between...... pain intensity and postural sway in adults (aged 50 or less) with non-specific low back pain. Methods: Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled. Center of pressure parameters were measured by three static bipedal standing tasks of 90...

Guying to prevent wind sway influences loblolly pine growth and wood properties

Science.gov (United States)

James D. Burton; Diana M. Smith

1972-01-01

Restraining young loblolly pine (Pinus taeda L.) trees from normal swaying in the wind markedly reduced radial growth in the immobilized portion of the bole and accelerated it in the upper, free-swaying portion. Guying also reduced specific gravity, number of earlywood and latewood tracheids, latewood tracheid diameter, and amount of compression wood...

Loss of Peripheral Sensory Function Explains Much of the Increase in Postural Sway in Healthy Older Adults

Directory of Open Access Journals (Sweden)

Eric Anson

2017-06-01

Full Text Available Postural sway increases with age and peripheral sensory disease. Whether, peripheral sensory function is related to postural sway independent of age in healthy adults is unclear. Here, we investigated the relationship between tests of visual function (VISFIELD, vestibular function (CANAL or OTOLITH, proprioceptive function (PROP, and age, with center of mass sway area (COM measured with eyes open then closed on firm and then a foam surface. A cross-sectional sample of 366 community dwelling healthy adults from the Baltimore Longitudinal Study of Aging was tested. Multiple linear regressions examined the association between COM and VISFIELD, PROP, CANAL, and OTOLITH separately and in multi-sensory models controlling for age and gender. PROP dominated sensory prediction of sway across most balance conditions (β's = 0.09–0.19, p's < 0.001, except on foam eyes closed where CANAL function loss was the only significant sensory predictor of sway (β = 2.12, p < 0.016. Age was not a consistent predictor of sway. This suggests loss of peripheral sensory function explains much of the age-associated increase in sway.

The relation between postural sway magnitude and metabolic energy cost during upright standing on a compliant surface.

NARCIS (Netherlands)

Houdijk, J.H.P.; Brown, S.; van Dieen, J.H.

2015-01-01

Postural control performance is often described in terms of postural sway magnitude, assuming that lower sway magnitude reflects better performance. However, people do not typically minimize sway magnitude when performing a postural control task. Possibly, other criteria are satisfied when people

The influence of age, anxiety and concern about falling on postural sway when standing at an elevated level.

Science.gov (United States)

Sturnieks, Daina L; Delbaere, Kim; Brodie, Matthew A; Lord, Stephen R

2016-10-01

Psychological processes may influence balance and contribute to the risk of falls in older people. While a self-reported fear of falling is associated with increased postural sway, inducing fear using an elevated platform can lead to reduced sway, suggesting different underlying mechanisms whereby fear may influence balance control. This study examined changes in postural sway, muscle activity and physiological measures of arousal while standing on a 65cm elevated platform, compared to floor level, in young and older adults. The older adults were classified as fall concerned or not fall concerned based on the Falls Efficacy Scale-International and anxious or not anxious based on the Goldberg Anxiety Scale. Fall concern did not affect the physiological and sway response to the elevated platform. In response to the postural threat, the anxious participants increased their sway frequency (p=0.001) but did not reduce sway range (p=0.674). Conversely, non-anxious participants showed an adaptive tightening of balance control, effectively reducing sway range in the elevated condition (ppostural control strategies under threatening conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

The effects of brief swaying on postural control.

Science.gov (United States)

Pagé, Sara; Maheu, Maxime; Landry, Simon P; Champoux, François

2017-12-06

Postural control can be improved with balance training. However, the nature and duration of the training required to enhance posture remains unclear. We studied the effects of 5 min of a self-initiated balance exercise along a single axis on postural control in healthy individuals. Postural control was measured before and after a 5-min period where members of the experimental group were asked to lean their entire body forward and backward and members of the control group were asked to remain seated. A significant improvement for sway velocity, a postural control variable significantly associated with an increased risk of falls, was found in the experimental group following the body sway exercise. These data suggest that a basic exercise can rapidly improve postural control and reduce the risk of falls.

Sports activities are reflected in the local stability and regularity of body sway : Older ice-skaters have better postural control than inactive elderly

NARCIS (Netherlands)

Lamoth, Claudine J. C.; van Heuvelen, Marieke J. G.

With age postural control deteriorates and increases the risk for falls. Recent research has suggested that in contrast to persons with superior balance control (dancer's athletes), with pathology and aging, predictability and regularity of sway patterns increase and stability decreases implying a

Is there a relationship between pain intensity and postural sway in patients with non-specific low back pain?

Science.gov (United States)

Ruhe, Alexander; Fejer, René; Walker, Bruce

2011-07-15

Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain, whereby the altered postural sway includes both higher mean sway velocities and larger sway area. No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults (aged 50 or less) with non-specific low back pain. Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled. Center of pressure parameters were measured by three static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11), an equal number of patients (n = 11) was enrolled per pain score. Generally, our results confirmed increased postural instability in pain sufferers compared to healthy controls. In addition, regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters. Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were reached with an incremental change in NRS scores of two to three points. COP mean velocity and sway area are closely related to self-reported pain scores. This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation.

Body sway reflects leadership in joint music performance.

Science.gov (United States)

Chang, Andrew; Livingstone, Steven R; Bosnyak, Dan J; Trainor, Laurel J

2017-05-23

The cultural and technological achievements of the human species depend on complex social interactions. Nonverbal interpersonal coordination, or joint action, is a crucial element of social interaction, but the dynamics of nonverbal information flow among people are not well understood. We used joint music making in string quartets, a complex, naturalistic nonverbal behavior, as a model system. Using motion capture, we recorded body sway simultaneously in four musicians, which reflected real-time interpersonal information sharing. We used Granger causality to analyze predictive relationships among the motion time series of the players to determine the magnitude and direction of information flow among the players. We experimentally manipulated which musician was the leader (followers were not informed who was leading) and whether they could see each other, to investigate how these variables affect information flow. We found that assigned leaders exerted significantly greater influence on others and were less influenced by others compared with followers. This effect was present, whether or not they could see each other, but was enhanced with visual information, indicating that visual as well as auditory information is used in musical coordination. Importantly, performers' ratings of the "goodness" of their performances were positively correlated with the overall degree of body sway coupling, indicating that communication through body sway reflects perceived performance success. These results confirm that information sharing in a nonverbal joint action task occurs through both auditory and visual cues and that the dynamics of information flow are affected by changing group relationships.

Is there a relationship between pain intensity and postural sway in patients with non-specific low back pain?

Directory of Open Access Journals (Sweden)

Fejer René

2011-07-01

Full Text Available Abstract Background Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain, whereby the altered postural sway includes both higher mean sway velocities and larger sway area. No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults (aged 50 or less with non-specific low back pain. Methods Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled. Center of pressure parameters were measured by three static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11, an equal number of patients (n = 11 was enrolled per pain score. Results Generally, our results confirmed increased postural instability in pain sufferers compared to healthy controls. In addition, regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters. Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were reached with an incremental change in NRS scores of two to three points. Conclusions COP mean velocity and sway area are closely related to self-reported pain scores. This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation.

Locomotor Sensory Organization Test: How Sensory Conflict Affects the Temporal Structure of Sway Variability During Gait.

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Chien, Jung Hung; Mukherjee, Mukul; Siu, Ka-Chun; Stergiou, Nicholas

2016-05-01

When maintaining postural stability temporally under increased sensory conflict, a more rigid response is used where the available degrees of freedom are essentially frozen. The current study investigated if such a strategy is also utilized during more dynamic situations of postural control as is the case with walking. This study attempted to answer this question by using the Locomotor Sensory Organization Test (LSOT). This apparatus incorporates SOT inspired perturbations of the visual and the somatosensory system. Ten healthy young adults performed the six conditions of the traditional SOT and the corresponding six conditions on the LSOT. The temporal structure of sway variability was evaluated from all conditions. The results showed that in the anterior posterior direction somatosensory input is crucial for postural control for both walking and standing; visual input also had an effect but was not as prominent as the somatosensory input. In the medial lateral direction and with respect to walking, visual input has a much larger effect than somatosensory input. This is possibly due to the added contributions by peripheral vision during walking; in standing such contributions may not be as significant for postural control. In sum, as sensory conflict increases more rigid and regular sway patterns are found during standing confirming the previous results presented in the literature, however the opposite was the case with walking where more exploratory and adaptive movement patterns are present.

Day-to-Day Variability of Postural Sway and Its Association With Cognitive Function in Older Adults: A Pilot Study

Directory of Open Access Journals (Sweden)

Julia M. Leach

2018-05-01

Full Text Available Introduction: Increased variability in motor function has been observed during the initial stages of cognitive decline. However, the natural variability of postural control, as well as its association with cognitive status and decline, remains unknown. The objective of this pilot study was to characterize the day-to-day variability in postural sway in non-demented older adults. We hypothesized that older adults with a lower cognitive status would have higher day-to-day variability in postural sway.Materials and Methods: A Nintendo Wii balance board (WBB was used to quantify postural sway in the home twice daily for 30 days in 20 non-demented, community-dwelling older adults: once under a single-task condition and once under a dual-task condition (using a daily word search task administered via a Nook tablet. Mean sway distance, velocity, area, centroidal frequency and frequency dispersion were derived from the center of pressure data acquired from the WBB.Results: Linear relationships were observed between the day-to-day variability in postural sway and cognitive status (indexed by cognitive global z-scores. More variability in time-domain postural sway (sway distance and area and less variability in frequency-domain postural sway (centroidal sway frequency were associated with a lower cognitive status under both the single- and dual-task conditions. Additionally, lower cognitive performance rates on the daily word search task were related to a lower cognitive status.Discussion: This small pilot study conducted on a short time scale motivates large-scale implementations over more extended time periods. Tracking longitudinal changes in postural sway may further our understanding of early-stage postural decline and its association with cognitive decline and, in turn, may aid in the early detection of dementia during preclinical stages when the utility of disease-modifying therapies would be greatest.

An improved input shaping design for an efficient sway control of a nonlinear 3D overhead crane with friction

Science.gov (United States)

Maghsoudi, Mohammad Javad; Mohamed, Z.; Sudin, S.; Buyamin, S.; Jaafar, H. I.; Ahmad, S. M.

2017-08-01

This paper proposes an improved input shaping scheme for an efficient sway control of a nonlinear three dimensional (3D) overhead crane with friction using the particle swarm optimization (PSO) algorithm. Using this approach, a higher payload sway reduction is obtained as the input shaper is designed based on a complete nonlinear model, as compared to the analytical-based input shaping scheme derived using a linear second order model. Zero Vibration (ZV) and Distributed Zero Vibration (DZV) shapers are designed using both analytical and PSO approaches for sway control of rail and trolley movements. To test the effectiveness of the proposed approach, MATLAB simulations and experiments on a laboratory 3D overhead crane are performed under various conditions involving different cable lengths and sway frequencies. Their performances are studied based on a maximum residual of payload sway and Integrated Absolute Error (IAE) values which indicate total payload sway of the crane. With experiments, the superiority of the proposed approach over the analytical-based is shown by 30-50% reductions of the IAE values for rail and trolley movements, for both ZV and DZV shapers. In addition, simulations results show higher sway reductions with the proposed approach. It is revealed that the proposed PSO-based input shaping design provides higher payload sway reductions of a 3D overhead crane with friction as compared to the commonly designed input shapers.

Body sway reflects leadership in joint music performance

Science.gov (United States)

Livingstone, Steven R.; Bosnyak, Dan J.; Trainor, Laurel J.

2017-01-01

The cultural and technological achievements of the human species depend on complex social interactions. Nonverbal interpersonal coordination, or joint action, is a crucial element of social interaction, but the dynamics of nonverbal information flow among people are not well understood. We used joint music making in string quartets, a complex, naturalistic nonverbal behavior, as a model system. Using motion capture, we recorded body sway simultaneously in four musicians, which reflected real-time interpersonal information sharing. We used Granger causality to analyze predictive relationships among the motion time series of the players to determine the magnitude and direction of information flow among the players. We experimentally manipulated which musician was the leader (followers were not informed who was leading) and whether they could see each other, to investigate how these variables affect information flow. We found that assigned leaders exerted significantly greater influence on others and were less influenced by others compared with followers. This effect was present, whether or not they could see each other, but was enhanced with visual information, indicating that visual as well as auditory information is used in musical coordination. Importantly, performers’ ratings of the “goodness” of their performances were positively correlated with the overall degree of body sway coupling, indicating that communication through body sway reflects perceived performance success. These results confirm that information sharing in a nonverbal joint action task occurs through both auditory and visual cues and that the dynamics of information flow are affected by changing group relationships. PMID:28484007

Testing the assumption of normality in body sway area calculations during unipedal stance tests with an inertial sensor.

Science.gov (United States)

Kyoung Jae Kim; Lucarevic, Jennifer; Bennett, Christopher; Gaunaurd, Ignacio; Gailey, Robert; Agrawal, Vibhor

2016-08-01

The quantification of postural sway during the unipedal stance test is one of the essentials of posturography. A shift of center of pressure (CoP) is an indirect measure of postural sway and also a measure of a person's ability to maintain balance. A widely used method in laboratory settings to calculate the sway of body center of mass (CoM) is through an ellipse that encloses 95% of CoP trajectory. The 95% ellipse can be computed under the assumption that the spatial distribution of the CoP points recorded from force platforms is normal. However, to date, this assumption of normality has not been demonstrated for sway measurements recorded from a sacral inertial measurement unit (IMU). This work provides evidence for non-normality of sway trajectories calculated at a sacral IMU with injured subjects as well as healthy subjects.

An input shaping controller enabling cranes to move without sway

International Nuclear Information System (INIS)

Singer, N.; Singhose, W.; Kriikku, E.

1997-01-01

A gantry crane at the Savannah River Technology Center was retrofitted with an Input Shaping controller. The controller intercepts the operator's pendant commands and modifies them in real time so that the crane is moved without residual sway in the suspended load. Mechanical components on the crane were modified to make the crane suitable for the anti-sway algorithm. This paper will describe the required mechanical modifications to the crane, as well as, a new form of Input Shaping that was developed for use on the crane. Experimental results are presented which demonstrate the effectiveness of the new process. Several practical considerations will be discussed including a novel (patent pending) approach for making small, accurate moves without residual oscillations

Postural sway in individuals with type 2 diabetes and concurrent benign paroxysmal positional vertigo.

Science.gov (United States)

D'Silva, Linda J; Kluding, Patricia M; Whitney, Susan L; Dai, Hongying; Santos, Marcio

2017-12-01

diabetes has been shown to affect the peripheral vestibular end organs and is associated with an increase in the frequency of benign paroxysmal positional vertigo (BPPV). People with diabetes have higher postural sway; however, the impact of symptomatic BPPV on postural sway in individuals with diabetes is unclear. The purpose of this cross-sectional study was to examine postural sway in people with type 2 diabetes who have symptomatic, untreated BPPV (BPPVDM). fifty-two participants (mean age 56.9 ± 5.6 years) were enrolled: controls (n = 14), diabetes (n = 14), BPPV only (n = 13) and BPPVDM (n = 11). An inertial motion sensor was used to detect pelvic acceleration across five standing conditions with eyes open/closed on firm/foam surfaces. Range of acceleration (cm/s 2 ), peak velocity (cm/s) and variability of sway [root mean square (RMS)] in the anterior-posterior (AP) and medial-lateral (ML) directions were used to compare postural sway between groups across conditions. participants with BPPVDM had higher ranges of acceleration in the AP (p = 0.02) and ML (p = 0.02) directions, as well as higher peak velocity (p diabetes groups. Standing on foam with eyes closed and tandem stance were challenging conditions for people with BPPVDM. clinicians may consider using standing on foam with eyes closed and tandem standing with eyes open to assess postural control in people with BPPVDM to identify postural instability.

Thioridazine dose-related effects on biomechanical force platform measures of sway in young and old men.

Science.gov (United States)

Liu, Y J; Stagni, G; Walden, J G; Shepherd, A M; Lichtenstein, M J

1998-04-01

Thioridazine (TDZ) is associated with an increased risk of falls. The purpose of this study was to determine whether (1) thioridazine increases Biomechanics Force Platform (BFP) measures of sway in a dose-related manner, (2) there is a difference in sway between young and old men, (3) there is a correlation between sway and orthostatic changes in BP and HR. Seven younger (aged 20-42) and five older (aged 70-76) healthy male volunteers received, in a randomized order double-blind design, a single oral dose of 0, 25, and 50 mg of TDZ on three separate days at least 7 days apart and 75 mg on the fourth day of the study. Sway and blood pressure were measured for 24 hours. A general clinical research center. Biomechanics force platform measures of postural sway were measured as the movement of the center of pressure. The elliptical area (EA) and average velocity (AV) were calculated with eyes open and eyes closed. Blood pressure and heart rate were measured for 5 minutes supine and 5 minutes standing. Thioridazine increases BFP sway in a dose-dependent manner. EA increased from 0.56 (SD = .51) cm2 for placebo to 0.88 (SD = 1.09) cm2 for 75 mg TDZ. AV increased from 1.07 (SD = .27) cm/sec, placebo, to 1.43 (SD = .55) cm/sec, 75 mg TDZ. Older men swayed more than younger men. Changes followed the expected time course for TDZ. EA and AV were associated with HR and BP, e.g., SBP versus ln(EA) and ln(AV) (r = -0.21 and r = -0.22, respectively; P fall risk dose dependently in young and old men. This may explain the effects of neuroleptic drugs on fall risk in older people.

Pain relief is associated with decreasing postural sway in patients with non-specific low back pain

DEFF Research Database (Denmark)

Ruhe, A.; Fejer, René; Walker, B.

2012-01-01

is maintained if pain levels change in adults with non-specific low back pain. Methods: Thirty-eight patients with non-specific low back pain and a matching number of healthy controls were enrolled. Postural sway was measured by three identical static bipedal standing tasks of 90 sec duration with eyes closed......Background: Increased postural sway is well documented in patients suffering from non-specific low back pain, whereby a linear relationship between higher pain intensities and increasing postural sway has been described. No investigation has been conducted to evaluate whether this relationship...... in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS 11). The patients received three manual interventions (e. g. manipulation, mobilization or soft tissue techniques) at 3-4 day intervals, postural sway measures were obtained at each occasion. Results...

Conjugated polymer dots for ultra-stable full-color fluorescence patterning.

Science.gov (United States)

Chang, Kaiwen; Liu, Zhihe; Chen, Haobin; Sheng, Lan; Zhang, Sean Xiao-An; Chiu, Daniel T; Yin, Shengyan; Wu, Changfeng; Qin, Weiping

2014-11-12

Stable full-color fluorescence patterning are achieved by multicolor polymer-dot inks. The fluorescent patterns show extraordinary stability upon various treatments, offering a superior combination of bright fluorescence, excellent photostability, chemical resistance, and eco-friendship. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Building and Calibration of a FAST Model of the SWAY Prototype Floating Wind Turbine: Preprint

Energy Technology Data Exchange (ETDEWEB)

Koh, J. H.; Robertson, A.; Jonkman, J.; Driscoll, F.; Ng, E. Y. K.

2013-09-01

Present efforts to verify and validate aero-hydro-servo-elastic numerical simulation tools that predict the dynamic response of a floating offshore wind turbine are primarily limited to code-to-code comparisons or code-to-data comparisons using data from wind-wave basin tests. In partnership with SWAY AS, the National Renewable Energy Laboratory (NREL) installed scientific wind, wave, and motion measurement equipment on the 1/6.5th-scale prototype SWAY floating wind system to collect data to validate a FAST model of the SWAY design in an open-water condition. Nanyang Technological University (NTU), through a collaboration with NREL, assisted in this validation.

Standing body sway in women with and without morning sickness in pregnancy.

Science.gov (United States)

Yu, Yawen; Chung, Hyun Chae; Hemingway, Lauren; Stoffregen, Thomas A

2013-01-01

Morning sickness typically is attributed to hormonal changes in pregnancy. We asked whether morning sickness is associated with changes in standing postural equilibrium, as occurs in research on visually induced motion sickness. Twenty-one pregnant women (mean age=30 years, mean height=163cm; mean weight=63kg) were tested during the first trimester. Laboratory-based balance measures were collected, along with perceived postural stability, the presence of morning sickness, and the severity of subjective symptoms. We varied the distance between the feet and the visual task performed during stance. Participants were classified as either experiencing (Sick, n=12) or not experiencing (Well, n=9) morning sickness. Perceived balance stability was lower for Sick than for Well women. The positional variability of sway was reduced for the Sick group, relative to the Well group. Positional variability decreased with wider stance width, and was reduced during performance of a more demanding visual task. Stance width and visual task also influenced the temporal dynamics of sway. Effects of stance width and visual task on postural sway were similar to effects in non-pregnant adults, suggesting that sensitive tuning of posture is maintained during the first trimester. The findings suggest that women with morning sickness may attempt to stabilize their bodies by reducing overall body sway. It may be useful to recommend that women adopt wider stance early in pregnancy. Copyright © 2012 Elsevier B.V. All rights reserved.

Body sway at sea for two visual tasks and three stance widths.

Science.gov (United States)

Stoffregen, Thomas A; Villard, Sebastien; Yu, Yawen

2009-12-01

On land, body sway is influenced by stance width (the distance between the feet) and by visual tasks engaged in during stance. While wider stance can be used to stabilize the body against ship motion and crewmembers are obliged to carry out many visual tasks while standing, the influence of these factors on the kinematics of body sway has not been studied at sea. Crewmembers of the RN Atlantis stood on a force plate from which we obtained data on the positional variability of the center of pressure (COP). The sea state was 2 on the Beaufort scale. We varied stance width (5 cm, 17 cm, and 30 cm) and the nature of the visual tasks. In the Inspection task, participants viewed a plain piece of white paper, while in the Search task they counted the number of target letters that appeared in a block of text. Search task performance was similar to reports from terrestrial studies. Variability of the COP position was reduced during the Search task relative to the Inspection task. Variability was also reduced during wide stance relative to narrow stance. The influence of stance width was greater than has been observed in terrestrial studies. These results suggest that two factors that influence postural sway on land (variations in stance width and in the nature of visual tasks) also influence sway at sea. We conclude that--in mild sea states--the influence of these factors is not suppressed by ship motion.

Gender differences in body-sway factors of center of foot pressure in a static upright posture and under the influence of alcohol intake.

Science.gov (United States)

Kitabayashi, Tamotsu; Demura, Shinichi; Noda, Masahiro; Yamada, Takayoshi

2004-07-01

This study aimed to examine gender differences in 4 body-sway factors of the center of foot pressure (CFP) during a static upright posture and the influence of alcohol intake on them. Four body-sway factors were interpreted in previous studies using factor analysis (the principal factor method and oblique solution by promax-rotation) on 220 healthy young males and females as follows; unit time sway, front-back sway, left-right sway and high frequency band power. The CFP measurement for 1 min was carried out twice with 1 min rest. The measurements of blood pressure, heart rate, whole body reaction time, standing on one leg with eyes closed, and CFP were carried out before and after the alcohol intake using 11 healthy young males and females. The measurement device used was an Anima's stabilometer G5500. The data sampling frequency was 20 Hz. Reliability of 4 body-sway factors was very high. Significant gender differences were found in the left-right sway and the high frequency band power factors, but the influence on body-sway is, as a whole, can be disregarded. These four sway factors can determine the influence of alcohol intake as efficient as 32 sway parameters.

Does postural sway change in association with manual therapeutic interventions? A review of the literature

Directory of Open Access Journals (Sweden)

Ruhe Alexander

2013-02-01

Full Text Available Abstract Study design Literature Review Objectives The objective of this literature review was to determine if postural sway changes in association with manual therapeutic interventions and to investigate whether any changes occur in healthy individuals or in association with pain intensity. Summary of Background data Improving postural stability has been proposed as a goal of manual therapeutic interventions. So far, no literature review has addressed whether there is supportive evidence for this and if so, what factors may be associated or causative for observed sway alterations. Search methods Seven online databases (PubMed, MEDLINE, EMBASE, CINAHL, Web of Science, ScienceDirect and the Cochrane library were systematically searched followed by a manual search of the retrieved papers. Selection criteria Studies comparing postural sway derived from bipedal force plate measurements in association with a manual therapeutic intervention, ideally compared to a control group. Data collection and analysis Two reviewers independently screened titles and abstracts for relevance, conducted the data extraction and the risk of bias assessment which was conducted using the RTI item bank. A descriptive analysis was conducted as the heterogeneous study designs prevented pooling of data. Results Nine studies of varying methodological quality met the inclusion criteria. No direct comparison of data across the studies was possible. There was no evidence that manual interventions lead to a change in postural sway in healthy individuals regardless of the body regions addressed by the intervention. There was some indication that postural sway may change at follow-up measurements in pain sufferers; however, this may be due to variations in pain intensity rather than resulting from the intervention itself. Conclusions There is no conclusive scientific evidence that manual therapeutic interventions may exhibit any immediate or long-term effect on COP excursions. Any

Correlations between measurement time and different expansibility of the elastic tape on the rectus femoris and body sway index with plyometric exercise.

Science.gov (United States)

Yoon, Jung-Gyu

2018-01-01

[Purpose] The purpose of this study was to examine correlations between measurement time and different expansibility of the elastic tape on the rectus femoris and body sway index with plyometric exercise. [Subjects and Methods] The subjects of this study were 24 healthy men. C90 area, C90 angle, trace length, sway average velocity for body sway index were measured using a force plate by BT4. The collected data were analyzed using Kendall's coefficient of concordance. [Results] All of body sway index on measuring follow up 24 hours after removing tape were significantly decreased than before and right after plyometric exercise. No significant correlations were found between body sway index and different expansibility of the elastic tape. [Conclusion] It appears that different expansibility of the elastic tape does not affect the ability to body sway index. Carry over effect of taping was verified on measuring follow up 24 hours after removing tape through the decreasing body sway index.

Loss of otolith function with age is associated with increased postural sway measures.

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Serrador, Jorge M; Lipsitz, Lewis A; Gopalakrishnan, Gosala S; Black, F Owen; Wood, Scott J

2009-11-06

Loss of balance and increased fall risk is a common problem associated with aging. Changes in vestibular function occur with aging but the contribution of reduced vestibular otolith function to fall risk remains unknown. We examined a population of 151 healthy individuals (aged 21-93) for both balance (sway measures) and ocular counter-rolling (OCR) function. We assessed balance function with eyes open and closed on a firm surface, eyes open and closed on a foam surface and OCR during +/-20 degree roll tilt at 0.005 Hz. Subjects demonstrated a significant age-related reduction in OCR and increase in postural sway. The effect of age on OCR was greater in females than males. The reduction in OCR was strongly correlated with the mediolateral measures of sway with eyes closed. This correlation was also present in the elderly group alone, suggesting that aging alone does not account for this effect. OCR decreased linearly with age and at a greater rate in females than males. This loss of vestibular otolith-ocular function is associated with increased mediolateral measures of sway which have been shown to be related to increased risk of falls. These data suggest a role for loss of otolith function in contributing to fall risk in the elderly. Further prospective, longitudinal studies are necessary to confirm these findings.

Effects of external loads on postural sway during quiet stance in adults aged 20-80 years.

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Hill, M W; Duncan, M J; Oxford, S W; Kay, A D; Price, M J

2018-01-01

The purpose of this study was to investigate the effects of holding external loads on postural sway during upright stance across age decades. Sixty-five healthy adults (females, n = 35), aged 18-80 years were assessed in four conditions; (1) standing without holding a load, holding a load corresponding to 5% body mass in the (2) left hand, (3) right hand and (4) both hands. The centre of pressure (COP) path length and anteroposterior and mediolateral COP displacement were used to indirectly assess postural sway. External loading elicited reductions in COP measures of postural sway in older age groups only (P  0.05). Holding external loads during standing is relevant to many activities of daily living (i.e. holding groceries). The reduction in postural sway may suggest this type of loading has a stabilising effect during quiet standing among older adults. Copyright © 2017 Elsevier Ltd. All rights reserved.

Eye movement instructions modulate motion illusion and body sway with Op Art.

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Kapoula, Zoï; Lang, Alexandre; Vernet, Marine; Locher, Paul

2015-01-01

Op Art generates illusory visual motion. It has been proposed that eye movements participate in such illusion. This study examined the effect of eye movement instructions (fixation vs. free exploration) on the sensation of motion as well as the body sway of subjects viewing Op Art paintings. Twenty-eight healthy adults in orthostatic stance were successively exposed to three visual stimuli consisting of one figure representing a cross (baseline condition) and two Op Art paintings providing sense of motion in depth-Bridget Riley's Movements in Squares and Akiyoshi Kitaoka's Rollers. Before their exposure to the Op Art images, participants were instructed either to fixate at the center of the image (fixation condition) or to explore the artwork (free viewing condition). Posture was measured for 30 s per condition using a body fixed sensor (accelerometer). The major finding of this study is that the two Op Art paintings induced a larger antero-posterior body sway both in terms of speed and displacement and an increased motion illusion in the free viewing condition as compared to the fixation condition. For body sway, this effect was significant for the Riley painting, while for motion illusion this effect was significant for Kitaoka's image. These results are attributed to macro-saccades presumably occurring under free viewing instructions, and most likely to the small vergence drifts during fixations following the saccades; such movements in interaction with visual properties of each image would increase either the illusory motion sensation or the antero-posterior body sway.

Motion in images is essential to cause motion sickness symptoms, but not to increase postural sway

NARCIS (Netherlands)

Lubeck, A.J.A.; Bos, J.E.; Stins, J.F.

2015-01-01

Abstract Objective It is generally assumed that motion in motion images is responsible for increased postural sway as well as for visually induced motion sickness (VIMS). However, this has not yet been tested. To that end, we studied postural sway and VIMS induced by motion and still images. Method

Effects of visual motion consistent or inconsistent with gravity on postural sway.

Science.gov (United States)

Balestrucci, Priscilla; Daprati, Elena; Lacquaniti, Francesco; Maffei, Vincenzo

2017-07-01

Vision plays an important role in postural control, and visual perception of the gravity-defined vertical helps maintaining upright stance. In addition, the influence of the gravity field on objects' motion is known to provide a reference for motor and non-motor behavior. However, the role of dynamic visual cues related to gravity in the control of postural balance has been little investigated. In order to understand whether visual cues about gravitational acceleration are relevant for postural control, we assessed the relation between postural sway and visual motion congruent or incongruent with gravity acceleration. Postural sway of 44 healthy volunteers was recorded by means of force platforms while they watched virtual targets moving in different directions and with different accelerations. Small but significant differences emerged in sway parameters with respect to the characteristics of target motion. Namely, for vertically accelerated targets, gravitational motion (GM) was associated with smaller oscillations of the center of pressure than anti-GM. The present findings support the hypothesis that not only static, but also dynamic visual cues about direction and magnitude of the gravitational field are relevant for balance control during upright stance.

Postural orientation and equilibrium processes associated with increased postural sway in autism spectrum disorder (ASD).

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Wang, Zheng; Hallac, Rami R; Conroy, Kaitlin C; White, Stormi P; Kane, Alex A; Collinsworth, Amy L; Sweeney, John A; Mosconi, Matthew W

2016-01-01

Increased postural sway has been repeatedly documented in children with autism spectrum disorder (ASD). Characterizing the control processes underlying this deficit, including postural orientation and equilibrium, may provide key insights into neurophysiological mechanisms associated with ASD. Postural orientation refers to children's ability to actively align their trunk and head with respect to their base of support, while postural equilibrium is an active process whereby children coordinate ankle dorsi-/plantar-flexion and hip abduction/adduction movements to stabilize their upper body. Dynamic engagement of each of these control processes is important for maintaining postural stability, though neither postural orientation nor equilibrium has been studied in ASD. Twenty-two children with ASD and 21 age and performance IQ-matched typically developing (TD) controls completed three standing tests. During static stance, participants were instructed to stand as still as possible. During dynamic stances, participants swayed at a comfortable speed and magnitude in either anterior-posterior (AP) or mediolateral (ML) directions. The center of pressure (COP) standard deviation and trajectory length were examined to determine if children with ASD showed increased postural sway. Postural orientation was assessed using a novel virtual time-to-contact (VTC) approach that characterized spatiotemporal dimensions of children's postural sway (i.e., body alignment) relative to their postural limitation boundary, defined as the maximum extent to which each child could sway in each direction. Postural equilibrium was quantified by evaluating the amount of shared or mutual information of COP time series measured along the AP and ML directions. Consistent with prior studies, children with ASD showed increased postural sway during both static and dynamic stances relative to TD children. In regard to postural orientation processes, children with ASD demonstrated reduced spatial

Increased postural sway during quiet stance as a risk factor for prospective falls in community-dwelling elderly individuals.

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Johansson, Jonas; Nordström, Anna; Gustafson, Yngve; Westling, Göran; Nordström, Peter

2017-11-01

fall-related injuries constitute major health risks in older individuals, and these risks are projected to increase in parallel with increasing human longevity. Impaired postural stability is a potential risk factor related to falls, although the evidence is inconclusive, partly due to the lack of prospective studies. This study aimed to investigate how objective measures of postural sway predict incident falls. this prospectively observational study included 1,877 community-dwelling individuals aged 70 years who participated in the Healthy Ageing Initiative between June 2012 and December 2015. postural sway was measured during eyes-open (EO) and eyes-closed (EC) trials using the Wii Balance Board. Functional mobility, muscle strength, objective physical activity and cognitive performance were also measured. Participants reported incident falls 6 and 12 months after the examination. during follow-up, 255 (14%) prospective fallers were identified. Division of centre of pressure (COP) sway lengths into quintiles revealed a nonlinear distribution of falls for EO trial data, but not EC trial data. After adjustment for multiple confounders, fall risk was increased by 75% for participants with COP sway lengths ≥400 mm during the EO trial (odds ratio [OR] 1.75, 95% confidence interval [CI] 1.09-2.79), and approximately doubled for sway lengths ≥920 mm during the EC trial (OR 1.90, 95% CI 1.12-3.22). objective measures of postural sway independently predict incident falls in older community-dwelling men and women. Further studies are needed to evaluate whether postural sway length is of interest for the prediction of incident falls in clinical settings. © The Author 2017. Published by Oxford University Press on behalf of the British Geriatrics Society.All rights reserved. For permissions, please email: journals.permissions@oup.com

Influence of Electrotactile Tongue Feedback on Controlling Upright Stance during Rotational and/or Translational Sway-referencing with Galvanic Vestibular Stimulation

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Wood, Scott J.; Tyler, Mitchell E.; Bach-y-Rita, Paul; MacDougall, Hamish G.; Moore, Steven T.; Stallings, Valerie L.; Paloski, William H.; Black, F. Owen

2007-01-01

Integration of multi-sensory inputs to detect tilts relative to gravity is critical for sensorimotor control of upright orientation. Displaying body orientation using electrotactile feedback to the tongue has been developed by Bach-y-Rita and colleagues as a sensory aid to maintain upright stance with impaired vestibular feedback. MacDougall et al. (2006) recently demonstrated that unpredictably varying Galvanic vestibular stimulation (GVS) significantly increased anterior-posterior (AP) sway during rotational sway referencing with eyes closed. The purpose of this study was to assess the influence of electrotactile feedback on postural control performance with pseudorandom binaural bipolar GVS. Postural equilibrium was measured with a computerized hydraulic platform in 10 healthy adults (6M, 4F, 24-65 y). Tactile feedback (TF) of pitch and roll body orientation was derived from a two-axis linear accelerometer mounted on a torso belt and displayed on a 144-point electrotactile array held against the anterior dorsal tongue (BrainPort, Wicab, Inc., Middleton, WI). Subjects were trained to use TF by voluntarily swaying to draw figures on their tongue, both with and without GVS. Subjects were required to keep the intraoral display in their mouths on all trials, including those that did not provide TF. Subjects performed 24 randomized trials (20 s duration with eyes closed) including four support surface conditions (fixed, rotational sway-referenced, translating the support surface proportional to AP sway, and combined rotational-translational sway-referencing), each repeated twice with and without GVS, and with combined GVS and TF. Postural performance was assessed using deviations from upright (peak-to-peak and RMS sway) and convergence toward stability limits (time and distance to base of support boundaries). Postural stability was impaired with GVS in all platform conditions, with larger decrements in performance during trials with rotation sway

The Complexity of Standing Postural Sway Associates with Future Falls in Community-Dwelling Older Adults: The MOBILIZE Boston Study.

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Zhou, Junhong; Habtemariam, Daniel; Iloputaife, Ikechukwu; Lipsitz, Lewis A; Manor, Brad

2017-06-07

Standing postural control is complex, meaning that it is dependent upon numerous inputs interacting across multiple temporal-spatial scales. Diminished physiologic complexity of postural sway has been linked to reduced ability to adapt to stressors. We hypothesized that older adults with lower postural sway complexity would experience more falls in the future. 738 adults aged ≥70 years completed the Short Physical Performance Battery test (SPPB) test and assessments of single and dual-task standing postural control. Postural sway complexity was quantified using multiscale entropy. Falls were subsequently tracked for 48 months. Negative binomial regression demonstrated that older adults with lower postural sway complexity in both single and dual-task conditions had higher future fall rate (incident rate ratio (IRR) = 0.98, p = 0.02, 95% Confidence Limits (CL) = 0.96-0.99). Notably, participants in the lowest quintile of complexity during dual-task standing suffered 48% more falls during the four-year follow-up as compared to those in the highest quintile (IRR = 1.48, p = 0.01, 95% CL = 1.09-1.99). Conversely, traditional postural sway metrics or SPPB performance did not associate with future falls. As compared to traditional metrics, the degree of multi-scale complexity contained within standing postural sway-particularly during dual task conditions- appears to be a better predictor of future falls in older adults.

Temporal changes in postural sway caused by ultrashort-acting hypnotics: triazolam and zolpidem.

Science.gov (United States)

Nakamura, M; Ishii, M; Niwa, Y; Yamazaki, M; Ito, H

2005-01-01

Two ultrashort-acting hypnotics, triazolam 0.25 mg and zolpidem 10 mg, were studied for their effects on equilibrium function in humans. Eight healthy male subjects participated in a double-blind, placebo-controlled study after informed consent. They subjected to static equilibrium tests, oculomotor tests and an assay of drug concentrations in the blood. Zolpidem was statistically significant in postural sway in tandem stance test, as defined by parametric values of tracing sum length and polygonal area of foot pressure center measured by a gait analysis system. In the tandem stance test, triazolam was statistically significant in postural sway only as defined by the polygonal area. However, in the Romberg test, the only statistically significant difference in zolpidem use was observed in polygonal area values. Blood concentrations of triazolam and zolpidem were found to closely correlate with the extent of postural sway in both tandem stance and Romberg tests. In this study, zolpidem with minimal muscle-relaxant effect incurred imbalance more extensively than triazolam, which is known for its effect of muscle relaxation. In addition, gaze deviation nystagmus was observed only in zolpidem use in 5 of 8 subjects (62.5%). From these results, it is suggested that in the use of hypnotics, sway derives from the suppression of the central nervous system relevant to awakening rather than from muscle relaxation. The prior reference to blood concentrations of hypnotics should help improve safety care in minimizing loss of balance control and possible fall. Copyright 2005 S. Karger AG, Basel.

Intersection of reality and fiction in art perception: pictorial space, body sway and mental imagery.

Science.gov (United States)

Ganczarek, Joanna; Ruggieri, V; Nardi, D; Olivetti Belardinelli, M

2015-09-01

The thesis of embodied cognition claims that perception of the environment entails a complex set of multisensory processes which forms a basis for the agent's potential and immediate actions. However, in the case of artworks, an agent becomes an observer and action turns into a reaction. This raises questions about the presence of embodied or situated cognition involved in art reception. The study aimed to assess the bodily correlates of perceiving fictional pictorial spaces in the absence of a possibility of an actual physical immersion or manipulation of represented forms. The subjects were presented with paintings by Vermeer and De Hooch, whilst their body sway and eye movements were recorded. Moreover, test and questionnaires on mental imagery (MRT, VVIQ and OSIQ) were administered. Three major results were obtained: (1) the degree of pictorial depth did not influence body sway; (2) fixations to distant elements in paintings (i.e. backgrounds) were accompanied by an increase in body sway; and (3) mental rotation test scores correlated positively with body sway. Our results suggest that in certain cases--despite the fictional character of art--observers' reactions resemble reactions to real stimuli. It is proposed that these reactions are mediated by mental imagery (e.g. mental rotation) that contributes to the act of representing alternative to real artistic spaces.

Kinesthetic motor imagery modulates body sway.

Science.gov (United States)

Rodrigues, E C; Lemos, T; Gouvea, B; Volchan, E; Imbiriba, L A; Vargas, C D

2010-08-25

The aim of this study was to investigate the effect of imagining an action implicating the body axis in the kinesthetic and visual motor imagery modalities upon the balance control system. Body sway analysis (measurement of center of pressure, CoP) together with electromyography (EMG) recording and verbal evaluation of imagery abilities were obtained from subjects during four tasks, performed in the upright position: to execute bilateral plantar flexions; to imagine themselves executing bilateral plantar flexions (kinesthetic modality); to imagine someone else executing the same movement (visual modality), and to imagine themselves singing a song (as a control imagery task). Body sway analysis revealed that kinesthetic imagery leads to a general increase in CoP oscillation, as reflected by an enhanced area of displacement. This effect was also verified for the CoP standard deviation in the medial-lateral direction. An increase in the trembling displacement (equivalent to center of pressure minus center of gravity) restricted to the anterior-posterior direction was also observed to occur during kinesthetic imagery. The visual imagery task did not differ from the control (sing) task for any of the analyzed parameters. No difference in the subjects' ability to perform the imagery tasks was found. No modulation of EMG data were observed across imagery tasks, indicating that there was no actual execution during motor imagination. These results suggest that motor imagery performed in the kinesthetic modality evokes motor representations involved in balance control. Copyright (c)10 IBRO. Published by Elsevier Ltd. All rights reserved.

Influence of age on postural sway during different dual-task conditions.

Directory of Open Access Journals (Sweden)

Marco eBergamin

2014-10-01

Full Text Available Dual-task performance assessments of competing parallel tasks and postural outcomes are growing in importance for geriatricians, as it is associated with predicting fall risk in older adults. This study aims to evaluate the postural stability during different dual-task conditions including visual (SMBT, verbal (CBAT and cognitive (MAT tasks in comparison with the standard Romberg’s open eyes position (OE. Furthermore, these conditions were investigated in a sample of young adults and a group of older healthy subjects to examine a potential interaction between type of secondary task and age status. To compare these groups across the four conditions, a within-between mixed model ANOVA was applied. Thus, a stabilometric platform has been used to measure center of pressure velocity (CoPV, sway area (SA, antero-posterior (AP and medio-lateral (ML oscillations as extents of postural sway. Tests of within-subjects effects indicated that different four conditions influenced the static balance for CoPV (p<0.001, SA (p<0.001. Post-hoc analyses indicated that CBAT task induced the worst balance condition on CoPV and resulted in significantly worse scores than OE (-11.4%; p<0.05, SMBT (-17.8% p<0.01 and MAT (-17.8% p<0.01 conditions; the largest SA was found in OE, and it was statistically larger than SMBT (-27.0%, p<0.01 and MAT (-23.1%; p<0.01. The between-subjects analysis indicated a general lower balance control in the group of elderly subjects (CoPV p<0.001, SA p<0.002, while, the mixed model ANOVA did not detect any interaction effect between types of secondary task and groups in any parameters (CoPV p=0.154, SA p=0.125. Postural sway during dual-task assessments was also found to decrease with advancing age, however, no interactions between aging and types of secondary tasks were found. Overall, these results indicated that the secondary task which most influenced the length of sway path, as measured by postural stability was a simple verbal

Resting State Default Mode Network Connectivity, Dual Task Performance, Gait Speed, and Postural Sway in Older Adults with Mild Cognitive Impairment.

Science.gov (United States)

Crockett, Rachel A; Hsu, Chun Liang; Best, John R; Liu-Ambrose, Teresa

2017-01-01

Aging is associated with an increased risk of falling. In particular, older adults with mild cognitive impairment (MCI) are more vulnerable to falling compared with their healthy counterparts. Major contributors to this increased falls risk include a decline in dual task performance, gait speed, and postural sway. Recent evidence highlights the potential influence of the default mode network (DMN), the frontoparietal network (FPN), and the supplementary motor area (SMA) on dual task performance, gait speed, and postural sway. The DMN is active during rest and deactivates during task-oriented processes, to maintain attention and stay on task. The FPN and SMA are involved in top-down attentional control, motor planning, and motor execution. The DMN shows less deactivation during task in older adults with MCI. This lack of deactivation is theorized to increase competition for resources between the DMN and task-related brain regions (e.g., the FPN and SMA), increasing distraction from the task and reducing task performance. However, no study has yet investigated the relationship between the between-network connectivity of the DMN with these regions and dual task walking, gait speed or postural sway. We hypothesized that greater functional connectivity both within the DMN and between DMN-FPN and DMN-SMA, will be associated with poorer performance during dual task walking, slower gait speed, and greater postural sway in older adults with MCI. Forty older adults with MCI were measured on a dual task-walking paradigm, gait speed over a 4-m walk, and postural sway using a sway-meter. Greater within-DMN connectivity was significantly correlated with poorer dual task performance. Furthermore, greater inter-network connectivity between the DMN and SMA was significantly correlated with slower gait speed and greater postural sway on the eyes open floor sway task. Thus, greater resting state DMN functional connectivity may be an underlying neural mechanism for reduced dual task

A Cable-Passive Damper System for Sway and Skew Motion Control of a Crane Spreader

Directory of Open Access Journals (Sweden)

La Duc Viet

2015-01-01

Full Text Available While the crane control problem is often approached by applying a certain active control command to some parts of the crane, this paper proposes a cable-passive damper system to reduce the vibration of a four-cable suspended crane spreader. The residual sway and skew motions of a crane spreader always produce the angle deflections between the crane cables and the crane spreader. The idea in this paper is to convert those deflections into energy dissipated by the viscous dampers, which connect the cables and the spreader. The proposed damper system is effective in reducing spreader sway and skew motions. Moreover, the optimal damping coefficient can be found analytically by minimizing the time integral of system energy. The numerical simulations show that the proposed passive system can assist the input shaping control of the trolley motion in reducing both sway and skew responses.

Combination of BTrackS and Geri-Fit as a targeted approach for assessing and reducing the postural sway of older adults with high fall risk.

Science.gov (United States)

Goble, Daniel J; Hearn, Mason C; Baweja, Harsimran S

2017-01-01

Atypically high postural sway measured by a force plate is a known risk factor for falls in older adults. Further, it has been shown that small, but significant, reductions in postural sway are possible with various balance exercise interventions. In the present study, a new low-cost force-plate technology called the Balance Tracking System (BTrackS) was utilized to assess postural sway of older adults before and after 90 days of a well-established exercise program called Geri-Fit. Results showed an overall reduction in postural sway across all participants from pre- to post-intervention. However, the magnitude of effects was significantly influenced by the amount of postural sway demonstrated by individuals prior to Geri-Fit training. Specifically, more participants with atypically high postural sway pre-intervention experienced an overall postural sway reduction. These reductions experienced were typically greater than the minimum detectable change statistic for the BTrackS Balance Test. Taken together, these findings suggest that BTrackS is an effective means of identifying older adults with elevated postural sway, who are likely to benefit from Geri-Fit training to mitigate fall risk.

Combination of BTrackS and Geri-Fit as a targeted approach for assessing and reducing the postural sway of older adults with high fall risk

Directory of Open Access Journals (Sweden)

Goble DJ

2017-02-01

Full Text Available Daniel J Goble, Mason C Hearn, Harsimran S Baweja School of Exercise and Nutritional Sciences, College of Health and Human Services, San Diego State University, San Diego, CA, USA Abstract: Atypically high postural sway measured by a force plate is a known risk factor for falls in older adults. Further, it has been shown that small, but significant, reductions in postural sway are possible with various balance exercise interventions. In the present study, a new low-cost force-plate technology called the Balance Tracking System (BTrackS was utilized to assess postural sway of older adults before and after 90 days of a well-established exercise program called Geri-Fit. Results showed an overall reduction in postural sway across all participants from pre- to post-intervention. However, the magnitude of effects was significantly influenced by the amount of postural sway demonstrated by individuals prior to Geri-Fit training. Specifically, more participants with atypically high postural sway pre-intervention experienced an overall postural sway reduction. These reductions experienced were typically greater than the minimum detectable change statistic for the BTrackS Balance Test. Taken together, these findings suggest that BTrackS is an effective means of identifying older adults with elevated postural sway, who are likely to benefit from Geri-Fit training to mitigate fall risk. Keywords: aging, balance, BTrackS, Geri-Fit, postural sway, fall risk

The effects of unstable surface balance training on postural sway, stability, functional ability and flexibility in women.

Science.gov (United States)

Nepocatych, Svetlana; Ketcham, Caroline J; Vallabhajosula, Srikant; Balilionis, Gytis

2018-01-01

This study examined the effects of balance training routine, using both sides utilized balance trainer (BOSU) and aerobic step (STEP) on postural sway and functional ability in middle-aged women. Twenty-seven females participated in the study, age 40.6±12.0 years, body mass 72.0±14.0 kg, height 164.0±7.7 cm, BMI 26.5±4.5 kg/m2, and relative body fat 33.1±7.4%. Participants were divided into two groups and performed progressive exercise routine on either STEP or BOSU for three weeks. Pre- and post-test consisted of Postural Sway Test performed on the Biodex Balance System, Functional Ability Test, Sit and Reach Test and Plank. A significant time effect was observed for both groups for sway index(P=0.029) and center of pressure antero-posterior (AP) displacement (P=0.038) but not for sway area or medio-lateral (ML) displacement (P>0.05). In addition, BOSU group had significantly lower Sway Index(P=0.048) and ML range (P=0.035) scores when vision and surface was altered compared to STEP group. A significant time effect was observed in walking-up the stairs (P=0.020), sit and reach test (P=0.035), and plank (Ptraining have a potential to induce adaptive responses in neuromuscular system that enhances postural control, balance and functional ability of women. The training using BOSU may help improve static balance and functional ability in women.

Correlation between Mechanical Properties of the Ankle Muscles and Postural Sway during the Menstrual Cycle.

Science.gov (United States)

Yim, JongEun; Petrofsky, Jerrold; Lee, Haneul

2018-03-01

Ankle and foot injuries are common among athletes and physically active individuals. The most common residual disability, ankle sprain, is characterized by instability along with postural sway. If the supporting structures around a joint become lax, posture stability and balance are also affected. Previous studies have examined muscle stiffness and elasticity and postural sway separately; however, the relationship between these factors is yet unknown. It is well known that the levels of sex hormones, especially estrogen, change in women over the phase of the menstrual cycle. Therefore, this study examined the relationship between the mechanical properties of tissue and balance activity using a non-invasive digital palpation device to determine if they undergo any changes over the menstrual cycle in young women. Sixteen young women with regular menstrual cycles completed the study. Tone, stiffness, and elasticity of the ankle muscles (lateral gastrocnemius, peroneus longus, and tibialis anterior) were measured using a non-invasive digital palpation device. Postural sway was recorded while the participants performed balance tasks during ovulation and menstruation. Significantly greater posture sway characteristics and ankle muscle elasticity were found during ovulation than during menstruation; lower tone and stiffness of the ankle muscles were observed at ovulation (p connective tissues. We therefore postulate that estrogen increases joint and muscle laxity and affects posture stability according to the phase of the menstrual cycle.

Influence of musical groove on postural sway.

Science.gov (United States)

Ross, Jessica M; Warlaumont, Anne S; Abney, Drew H; Rigoli, Lillian M; Balasubramaniam, Ramesh

2016-03-01

Timescales of postural fluctuation reflect underlying neuromuscular processes in balance control that are influenced by sensory information and the performance of concurrent cognitive and motor tasks. An open question is how postural fluctuations entrain to complex environmental rhythms, such as in music, which also vary on multiple timescales. Musical groove describes the property of music that encourages auditory-motor synchronization and is used to study voluntary motor entrainment to rhythmic sounds. The influence of groove on balance control mechanisms remains unexplored. We recorded fluctuations in center of pressure (CoP) of standing participants (N = 40) listening to low and high groove music and during quiet stance. We found an effect of musical groove on radial sway variability, with the least amount of variability in the high groove condition. In addition, we observed that groove influenced postural sway entrainment at various temporal scales. For example, with increasing levels of groove, we observed more entrainment to shorter, local timescale rhythmic musical occurrences. In contrast, we observed more entrainment to longer, global timescale features of the music, such as periodicity, with decreasing levels of groove. Finally, musical experience influenced the amount of postural variability and entrainment at local and global timescales. We conclude that groove in music and musical experience can influence the neural mechanisms that govern balance control, and discuss implications of our findings in terms of multiscale sensorimotor coupling. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Do voluntary strength, proprioception, range of motion, or postural sway predict occurrence of lateral ankle sprain?

OpenAIRE

de Noronha, M; Refshauge, K M; Herbert, R D; Kilbreath, S L

2006-01-01

Prevention of ankle sprain, the most common sporting injury, is only possible once risk factors have been identified. Voluntary strength, proprioception, postural sway, and range of motion are possible risk factors. A systematic review was carried out to investigate these possiblities. Eligible studies were those with longitudinal design investigating ankle sprain in subjects aged ⩾15 years. The studies had to have measured range of motion, voluntary strength, proprioception, or postural sway...

Sway as predictor of injuries in children

DEFF Research Database (Denmark)

Runge, Lisbeth; Kristensen, Peter Lund; Junge, Tina

2014-01-01

). Outcome measures Primary outcome was overuse and traumatic injuries, with special emphasis on ankle and knee sprains. Complaints were registered by SMS-track on a weekly basis, and after a telephone interview, clinicians examined and diagnosed the children with complaints. Injuries were diagnosed using...... ICD-10. Results Injuries: 2276, traumatic injuries: 714, ankle sprains: 164, knee sprains: 42 Preliminary multivariate analysis taking into account competing risk showed significant odds ratios (OR) at test 1; A) 1.003 per cm increase of sway; B) overall traumatic injury OR=3.0, ankle sprain OR=5...

MRI-related static magnetic stray fields and postural body sway: a double-blind randomized crossover study.

Science.gov (United States)

van Nierop, Lotte E; Slottje, Pauline; Kingma, Herman; Kromhout, Hans

2013-07-01

We assessed postural body sway performance after exposure to movement induced time-varying magnetic fields in the static magnetic stray field in front of a 7 Tesla (T) magnetic resonance imaging scanner. Using a double blind randomized crossover design, 30 healthy volunteers performed two balance tasks (i.e., standing with eyes closed and feet in parallel and then in tandem position) after standardized head movements in a sham, low exposure (on average 0.24 T static magnetic stray field and 0.49 T·s(-1) time-varying magnetic field) and high exposure condition (0.37 T and 0.70 T·s(-1)). Personal exposure to static magnetic stray fields and time-varying magnetic fields was measured with a personal dosimeter. Postural body sway was expressed in sway path, area, and velocity. Mixed-effects model regression analysis showed that postural body sway in the parallel task was negatively affected (P < 0.05) by exposure on all three measures. The tandem task revealed the same trend, but did not reach statistical significance. Further studies are needed to investigate the possibility of independent or synergetic effects of static magnetic stray field and time-varying magnetic field exposure. In addition, practical safety implications of these findings, e.g., for surgeons and others working near magnetic resonance imaging scanners need to be investigated. Copyright © 2012 Wiley Periodicals, Inc.

Can explicit visual feedback of postural sway efface the effects of sensory manipulations on mediolateral balance performance?

OpenAIRE

Cofre Lizama, L.E.; Pijnappels, M.A.G.M.; Reeves, N.P.; Verschueren, S.M.; van Dieen, J.H.

2016-01-01

Explicit visual feedback on postural sway is often used in balance assessment and training. However, up-weighting of visual information may mask impairments of other sensory systems. We therefore aimed to determine whether the effects of somatosensory, vestibular, and proprioceptive manipulations on mediolateral balance are reduced by explicit visual feedback on mediolateral sway of the body center of mass and by the presence of visual information. We manipulated sensory inputs of the somatos...

Stable structural color patterns displayed on transparent insect wings.

Science.gov (United States)

Shevtsova, Ekaterina; Hansson, Christer; Janzen, Daniel H; Kjærandsen, Jostein

2011-01-11

Color patterns play central roles in the behavior of insects, and are important traits for taxonomic studies. Here we report striking and stable structural color patterns--wing interference patterns (WIPs)--in the transparent wings of small Hymenoptera and Diptera, patterns that have been largely overlooked by biologists. These extremely thin wings reflect vivid color patterns caused by thin film interference. The visibility of these patterns is affected by the way the insects display their wings against various backgrounds with different light properties. The specific color sequence displayed lacks pure red and matches the color vision of most insects, strongly suggesting that the biological significance of WIPs lies in visual signaling. Taxon-specific color patterns are formed by uneven membrane thickness, pigmentation, venation, and hair placement. The optically refracted pattern is also stabilized by microstructures of the wing such as membrane corrugations and spherical cell structures that reinforce the pattern and make it essentially noniridescent over a large range of light incidences. WIPs can be applied to map the micromorphology of wings through direct observation and are useful in several fields of biology. We demonstrate their usefulness as identification patterns to solve cases of cryptic species complexes in tiny parasitic wasps, and indicate their potentials for research on the genetic control of wing development through direct links between the transregulatory wing landscape and interference patterns we observe in Drosophila model species. Some species display sexually dimorphic WIPs, suggesting sexual selection as one of the driving forces for their evolution.

Uncovering stable and occasional human mobility patterns: A case study of the Beijing subway

Science.gov (United States)

Yong, Nuo; Ni, Shunjiang; Shen, Shifei; Chen, Peng; Ji, Xuewei

2018-02-01

There have generally been two kinds of approaches to the empirical study of human mobility. At the group level, some valuable information might be submerged in statistical noise, while due to the diversity of individual purpose and preference, there is still no general statistical regularity of human mobility at the individual level. In this paper, we considered group-level human mobility as the combination of several basic patterns and analyzed the collective mobility by category. Utilizing matrix factorization and correlation analysis, we extracted some of the stable/occasional components from the collective human mobility in the Beijing subway and found that the departure and arrival mobility patterns have different characteristics, both in time and space, under various conditions. We classified individual records into different patterns and analyzed the most likely trip distance by category. The proposed method can decompose stable/occasional mobility patterns from the collective mobility and identify passengers belonging to different patterns, helping us to better understand the origin of different mobility patterns and provide guidance for emergency management of large crowds.

Stable, precise, and reproducible patterning of bicoid and hunchback molecules in the early Drosophila embryo.

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Yurie Okabe-Oho

2009-08-01

Full Text Available Precise patterning of morphogen molecules and their accurate reading out are of key importance in embryonic development. Recent experiments have visualized distributions of proteins in developing embryos and shown that the gradient of concentration of Bicoid morphogen in Drosophila embryos is established rapidly after fertilization and remains stable through syncytial mitoses. This stable Bicoid gradient is read out in a precise way to distribute Hunchback with small fluctuations in each embryo and in a reproducible way, with small embryo-to-embryo fluctuation. The mechanisms of such stable, precise, and reproducible patterning through noisy cellular processes, however, still remain mysterious. To address these issues, here we develop the one- and three-dimensional stochastic models of the early Drosophila embryo. The simulated results show that the fluctuation in expression of the hunchback gene is dominated by the random arrival of Bicoid at the hunchback enhancer. Slow diffusion of Hunchback protein, however, averages out this intense fluctuation, leading to the precise patterning of distribution of Hunchback without loss of sharpness of the boundary of its distribution. The coordinated rates of diffusion and transport of input Bicoid and output Hunchback play decisive roles in suppressing fluctuations arising from the dynamical structure change in embryos and those arising from the random diffusion of molecules, and give rise to the stable, precise, and reproducible patterning of Bicoid and Hunchback distributions.

Payoff non-linearity sways the effect of mistakes on the evolution of reciprocity.

Science.gov (United States)

Kurokawa, Shun

2016-09-01

The existence of cooperation is considered to require explanation, and reciprocity is a potential explanatory mechanism. Animals sometimes fail to cooperate even when they attempt to do so, and a reciprocator has an Achilles' heel: it is vulnerable to error (the interaction between two reciprocators can lead to an endless vendetta.). However, the strategy favored by natural selection is determined also by its interaction with other strategies. The relationship between two reciprocators leading to a collapse of cooperation through error does not straightforwardly imply that mistakes make the conditions under which reciprocity evolves stringent. Hence, mistakes may facilitate the evolution of reciprocity. However, it has been shown through the analysis of the interaction between reciprocators and unconditional defectors that the existence of mistakes makes the conditions for reciprocators stable against invasion by an unconditional defector more stringent, which indicates that mistakes discourage the evolution of reciprocity. However, this result is based on the assumption that the effects of cooperation are additive (payoff is linear), while the game played by real animals does not always display this feature. In such cases, the result may be swayed. In this paper, we remove this assumption, reexamining whether mistakes disturb the evolution of reciprocity. Using the analysis of an evolutionarily stable strategy (ESS), we show that when extra fitness costs are present in cases where mutual cooperation is established, mistakes can facilitate the evolution of reciprocity; whereas, when the effect of cooperation is additive, mistakes always disturb the evolution of reciprocity, as has been shown previously. Copyright © 2016. Published by Elsevier Inc.

An Evaluation of New Indices of Postural Sway in Patients with Knee Osteoarthritis

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SM Mohsenipour

2017-07-01

CONCLUSION: Results of the study demonstrated that patients with more difficult positions (RS, NTS have more sways than those with CDLS, especially in the lateral direction. Therefore, balancing and strengthening exercises are especially important in the lateral direction and in challenging situations.

The Complexity of Standing Postural Sway Associates with Future Falls in Community-Dwelling Older Adults: The MOBILIZE Boston Study

OpenAIRE

Zhou, Junhong; Habtemariam, Daniel; Iloputaife, Ikechukwu; Lipsitz, Lewis A.; Manor, Brad

2017-01-01

Standing postural control is complex, meaning that it is dependent upon numerous inputs interacting across multiple temporal-spatial scales. Diminished physiologic complexity of postural sway has been linked to reduced ability to adapt to stressors. We hypothesized that older adults with lower postural sway complexity would experience more falls in the future. 738 adults aged ?70 years completed the Short Physical Performance Battery test (SPPB) test and assessments of single and dual-task st...

Postural sway and gaze can track the complex motion of a visual target.

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Vassilia Hatzitaki

Full Text Available Variability is an inherent and important feature of human movement. This variability has form exhibiting a chaotic structure. Visual feedback training using regular predictive visual target motions does not take into account this essential characteristic of the human movement, and may result in task specific learning and loss of visuo-motor adaptability. In this study, we asked how well healthy young adults can track visual target cues of varying degree of complexity during whole-body swaying in the Anterior-Posterior (AP and Medio-Lateral (ML direction. Participants were asked to track three visual target motions: a complex (Lorenz attractor, a noise (brown and a periodic (sine moving target while receiving online visual feedback about their performance. Postural sway, gaze and target motion were synchronously recorded and the degree of force-target and gaze-target coupling was quantified using spectral coherence and Cross-Approximate entropy. Analysis revealed that both force-target and gaze-target coupling was sensitive to the complexity of the visual stimuli motions. Postural sway showed a higher degree of coherence with the Lorenz attractor than the brown noise or sinusoidal stimulus motion. Similarly, gaze was more synchronous with the Lorenz attractor than the brown noise and sinusoidal stimulus motion. These results were similar regardless of whether tracking was performed in the AP or ML direction. Based on the theoretical model of optimal movement variability tracking of a complex signal may provide a better stimulus to improve visuo-motor adaptation and learning in postural control.

Postural sway, falls, and cognitive status: a cross-sectional study among older adults.

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Mignardot, Jean-Baptiste; Beauchet, Olivier; Annweiler, Cédric; Cornu, Christophe; Deschamps, Thibault

2014-01-01

Cognitive impairment-related changes in postural sway increase fall risk among older adults. Better understanding this association could be helpful for fall prevention. To examine the center-of-pressure (COP) velocity association with cognitive status and history of falls, in cognitively healthy individuals (CHI), patients with mild cognitive impairment (MCI), and with mild-to-moderate Alzheimer's disease (MMAD). Six hundred and eleven older community-dwellers (77.2 ± 7.9 years; 51.8% men) were separated into CHI, MCI, and MMAD participants. By computing the average absolute maximal velocity (AAMV), the bounding limits of COP velocity dynamics were determined while participants were asked to maintain quiet stance on a force platform with eyes open or with eyes closed. Age, gender, history of falls, body mass index, medications, handgrip strength, Timed Up & Go score were used as covariates. The multivariate ANCOVA, with AAMV in eyes open and eyes closed conditions as dependent variables, showed that the highest AAMVs that bound the COP velocity dynamics of postural sway were associated with cognitive impairment (p = 0.048) (i.e., lowest limits in CHI and MCI as compared with MMAD) and falls (p = 0.033) (i.e., highest limits in fallers). These findings identified the bounding limits of COP velocity as a hallmark feature of cognitive impairment-related changes in postural sway, in particular for MMAD. This point is of special interest for clinical balance assessment and fall prevention in MMAD patients in order to plan long-term targeted fall-prevention programs.

Extended design method for in-plane stability of haunched sway portal frames

NARCIS (Netherlands)

van Hove, B.W.E.M.; Snijder, H.H.; Hofmeyer, H.; Altinga, N.

2017-01-01

In current design rules the effect of a haunch on the sway in-plane stability of a steel portal frame only takes into account the influence of the haunch dimensions on the beam-to-column connection strength and stiffness. The effect of the haunch dimensions on the beam behavior, and thus on the

Dual task interference on postural sway, postural transitions and gait in people with Parkinson's disease and freezing of gait.

Science.gov (United States)

de Souza Fortaleza, Ana Claudia; Mancini, Martina; Carlson-Kuhta, Patty; King, Laurie A; Nutt, John G; Chagas, Eliane Ferrari; Freitas, Ismael Forte; Horak, Fay B

2017-07-01

Freezing of gait (FoG) is associated with less automatic gait and more impaired cognition, balance and postural transitions compared to people with PD who do not have FoG. However, it is unknown whether dual-task cost during postural sway, postural transitions (such as gait initiation and turning), and gait are more in subjects with Parkinson's disease (PD) who have freezing of gait (FoG+) compared to those who do not have FoG (FoG-). Here, we hypothesized that the effects of a cognitive dual task on postural sway, postural transitions and gait would be larger in FoG+ than FoG-. Thirty FoG- and 24 FoG+ performed an Instrumented Stand and Walk test in OFF medication state, with and without a secondary cognitive task (serial subtraction by 3s). Measures of postural sway, gait initiation, turning, and walking were extracted using body-worn inertial sensors. FoG+ showed significantly larger dual task cost than FoG- for several gait metrics, but not during postural sway or postural transitions. During walking, FoG+ exhibited a larger dual task cost than FoG- resulting in shorter stride length and slower stride velocity. During standing, FoG+ showed a larger postural sway compared to FoG- and during gait initiation, FoG+, but not FoG-, showed a longer first step duration during the dual-task condition compared to single-task condition (interaction effect, p=0.04). During turning, both groups showed a slower turn peak speed in the dual-task condition compared to single task condition. These findings partly support our hypothesis that dual task cost on walking is greater in FoG+ than FoG-. Copyright © 2017. Published by Elsevier B.V.

Postural Sway Parameters and Gait Symmetry in Preschool Children: Cross-sectional study

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Fabiane E de Sá

Full Text Available Abstract The most important function of posture is to ensure the maintenance of control during the start and the continuation of human movement, moreover, posture serves as a reference for the production of precise movements. The aim of this study was to relate the postural sway parameters and gait symmetry in preschool children.This study is a cross-sectional study, conducted in 49 children with a mean age of 4.65 ± 0.44 years. Initially, height and body mass of children were measured using anthropometric scales. Next, an electronic baropodometer was used to evaluate the distribution of dynamic plantar pressure (gait and stabilometry (balance.A Student t test or Mann-Whitney test for comparing two groups was used. To correlate variables, a Pearson's correlation or Spearman's correlation coefficient was used. The stabilometric parameters showed no significant difference between an eyes open test and eyes closed test in preschool child. We found a moderate relationship between axis inclination and cadence symmetry (R=0.40;p=0.007. Postural sway parameters have relationship cadence symmetry of the gait in preschool children.

A user`s guide to LUGSAN II. A computer program to calculate and archive lug and sway brace loads for aircraft-carried stores

Energy Technology Data Exchange (ETDEWEB)

Dunn, W.N. [Sandia National Labs., Albuquerque, NM (United States). Mechanical and Thermal Environments Dept.

1998-03-01

LUG and Sway brace ANalysis (LUGSAN) II is an analysis and database computer program that is designed to calculate store lug and sway brace loads for aircraft captive carriage. LUGSAN II combines the rigid body dynamics code, SWAY85, with a Macintosh Hypercard database to function both as an analysis and archival system. This report describes the LUGSAN II application program, which operates on the Macintosh System (Hypercard 2.2 or later) and includes function descriptions, layout examples, and sample sessions. Although this report is primarily a user`s manual, a brief overview of the LUGSAN II computer code is included with suggested resources for programmers.

Adaptive output-based command shaping for sway control of a 3D overhead crane with payload hoisting and wind disturbance

Science.gov (United States)

Abdullahi, Auwalu M.; Mohamed, Z.; Selamat, H.; Pota, Hemanshu R.; Zainal Abidin, M. S.; Ismail, F. S.; Haruna, A.

2018-01-01

Payload hoisting and wind disturbance during crane operations are among the challenging factors that affect a payload sway and thus, affect the crane's performance. This paper proposes a new online adaptive output-based command shaping (AOCS) technique for an effective payload sway reduction of an overhead crane under the influence of those effects. This technique enhances the previously developed output-based command shaping (OCS) which was effective only for a fixed system and without external disturbances. Unlike the conventional input shaping design technique which requires the system's natural frequency and damping ratio, the proposed technique is designed by using the output signal and thus, an online adaptive algorithm can be formulated. To test the effectiveness of the AOCS, experiments are carried out using a laboratory overhead crane with a payload hoisting in the presence of wind, and with different payloads. The superiority of the method is confirmed by 82% and 29% reductions in the overall sway and the maximum transient sway respectively, when compared to the OCS, and two robust input shapers namely Zero Vibration Derivative-Derivative and Extra-Insensitive shapers. Furthermore, the method demonstrates a uniform crane's performance under all conditions. It is envisaged that the proposed method can be very useful in designing an effective controller for a crane system with an unknown payload and under the influence of external disturbances.

Effect of six weeks of dura disc and mini-trampoline balance training on postural sway in athletes with functional ankle instability.

Science.gov (United States)

Kidgell, Dawson J; Horvath, Deanna M; Jackson, Brendan M; Seymour, Philip J

2007-05-01

Lateral ankle sprain (LAS) is one of the most common injuries incurred during sporting activities, and effective rehabilitation programs for this condition are challenging to develop. The purpose of this research was to compare the effect of 6 weeks of balance training on either a mini-trampoline or a dura disc on postural sway and to determine if the mini-trampoline or the dura disc is more effective in improving postural sway. Twenty subjects (11 men, 9 women) with a mean age of 25.4 +/- 4.2 years were randomly allocated into a control group, a dura disc training (DT) group, or a mini-trampoline (MT) group. Subjects completed 6 weeks of balance training. Postural sway was measured by subjects performing a single limb stance on a force plate. The disbursement of the center of pressure was obtained from the force plate in the medial-lateral and the anterior-posterior sway path and was subsequently used for pretest and posttest analysis. After the 6-week training intervention, there was a significant (p 0.05) difference detected for improvements between the MT and DT groups. These results indicate that not only is the mini-trampoline an effective tool for improving balance after LAS, but it is equally as effective as the dura disc.

Postural sway and regional cerebellar volume in adults with attention-deficit/hyperactivity disorder

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Michael J. Hove

2015-01-01

Conclusion: These findings show that sway abnormalities commonly reported in children with ADHD are also present in adults, and for the first time show a relationship between postural control atypicalities and the cerebellum in this group. Our findings extend the literature on motor abnormalities in ADHD and contribute to our knowledge of their neural substrate.

TENS to the Lateral Aspect of the Knees During Stance Attenuates Postural Sway in Young Adults

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Yocheved Laufer

2007-01-01

Full Text Available Somatosensory input is known to be essential for postural control. The present study examined the effects on postural sway of sensory input delivered via transcutaneous electrical nerve stimulation (TENS applied to the knees during stance. Electrodes from a dual-channel portable TENS unit were adhered to the skin overlying the lateral and medial aspect of both knees of 20 young healthy volunteers (mean age 24.0 years, standard deviation 4.0. Postural sway parameters were obtained during static bipedal stance with an AMTI force platform. Four stimulation conditions were tested with eyes open and with eyes closed: no TENS; TENS applied bilaterally; and TENS applied to either the right or the left knee. Participants underwent two eight-trial blocks, with each trial lasting 30 seconds. The order of conditions was randomized for each participant. Stimulation consisted of a biphasic symmetrical stimulus delivered at the sensory detection level, with a pulse duration of 200μsec and a pulse frequency of 100Hz. The application of TENS induced significant reductions in mean sway velocity and in the medio-lateral dispersion of the center of pressure, with no corresponding effect on the anterior-posterior dispersion. These findings suggest that electrical stimulation delivered at the sensory detection level to the lateral aspects of the knees may be effective in improving balance control, and that this effect may be directionally specific.

[Temporal Analysis of Body Sway during Reciprocator Motion Movie Viewing].

Science.gov (United States)

Sugiura, Akihiro; Tanaka, Kunihiko; Wakatabe, Shun; Matsumoto, Chika; Miyao, Masaru

2016-01-01

We aimed to investigate the effect of stereoscopic viewing and the degree of awareness of motion sickness on posture by measuring body sway during motion movie viewing. Nineteen students (12 men and 7 women; age range, 21-24 years) participated in this study. The movie, which showed several balls randomly positioned, was projected on a white wall 2 m in front of the subjects through a two-dimensional (2-D)/three-dimensional (3-D) convertible projector. To measure body sway during movie viewing, the subjects stood statically erect on a Wii balance board, with the toe opening at 18 degrees. The study protocol was as follows: The subjects watched (1) a nonmoving movie for 1 minute as the pretest and then (2) a round-trip sinusoidally moving-in-depth-direction movie for 3 minutes. (3) The initial static movie was shown again for 1 minute. Steps (2) and (3) were treated as one trial, after which two trials (2-D and 3-D movies) were performed in a random sequence. In this study, we found that posture changed according to the motion in the movie and that the longer the viewing time, the higher the synchronization accuracy. These tendencies depended on the level of awareness of motion sickness or the 3-D movie viewed. The mechanism of postural change in movie viewing was not vection but self-defense to resolve sensory conflict between visual information (spatial swing) and equilibrium sense (motionlessness).

A data analysis method for identifying deterministic components of stable and unstable time-delayed systems with colored noise

Energy Technology Data Exchange (ETDEWEB)

Patanarapeelert, K. [Faculty of Science, Department of Mathematics, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand); Frank, T.D. [Institute for Theoretical Physics, University of Muenster, Wilhelm-Klemm-Str. 9, 48149 Muenster (Germany)]. E-mail: tdfrank@uni-muenster.de; Friedrich, R. [Institute for Theoretical Physics, University of Muenster, Wilhelm-Klemm-Str. 9, 48149 Muenster (Germany); Beek, P.J. [Faculty of Human Movement Sciences and Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam (Netherlands); Tang, I.M. [Faculty of Science, Department of Physics, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand)

2006-12-18

A method is proposed to identify deterministic components of stable and unstable time-delayed systems subjected to noise sources with finite correlation times (colored noise). Both neutral and retarded delay systems are considered. For vanishing correlation times it is shown how to determine their noise amplitudes by minimizing appropriately defined Kullback measures. The method is illustrated by applying it to simulated data from stochastic time-delayed systems representing delay-induced bifurcations, postural sway and ship rolling.

Girls with generalized joint hypermobility display changed muscle activity and postural sway during static balance tasks

DEFF Research Database (Denmark)

Juul-Kristensen, B; Johansen, Kl; Hendriksen, P

2016-01-01

OBJECTIVES: To study knee muscle activity and static postural sway in girls with generalized joint hypermobility (GJH). METHOD: Sixteen girls with GJH and 11 girls with non-GJH (NGJH) aged 14 years, randomly recruited among schoolchildren, participated in this study. GJH inclusion criteria were......: Beighton score minimum 6/9 and one hypermobile knee; for NGJH: Beighton score maximum 5/9 and no knees with hypermobility. The participants performed a static two-legged balance test with eyes open (2EO) and eyes closed (2EC) and a one-legged stance test with eyes open (1EO). Postural sway (centre......) of Q, H, and G muscle activity was calculated. Knee function was self-reported using the Knee Injury and Osteoarthritis Outcome Score for children (KOOS-Child). RESULTS: GJH had a significantly lower lateral HQ CCI and a higher medial/lateral HQ CCI ratio in all balance tasks. Group mean EMG varied...

Early embryonic chromosome instability results in stable mosaic pattern in human tissues.

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Hasmik Mkrtchyan

Full Text Available The discovery of copy number variations (CNV in the human genome opened new perspectives on the study of the genetic causes of inherited disorders and the aetiology of common diseases. Here, a single-cell-level investigation of CNV in different human tissues led us to uncover the phenomenon of mitotically derived genomic mosaicism, which is stable in different cell types of one individual. The CNV mosaic ratios were different between the 10 individuals studied. However, they were stable in the T lymphocytes, immortalized B lymphoblastoid cells, and skin fibroblasts analyzed in each individual. Because these cell types have a common origin in the connective tissues, we suggest that mitotic changes in CNV regions may happen early during embryonic development and occur only once, after which the stable mosaic ratio is maintained throughout the differentiated tissues. This concept is further supported by a unique study of immortalized B lymphoblastoid cell lines obtained with 20 year difference from two subjects. We provide the first evidence of somatic mosaicism for CNV, with stable variation ratios in different cell types of one individual leading to the hypothesis of early embryonic chromosome instability resulting in stable mosaic pattern in human tissues. This concept has the potential to open new perspectives in personalized genetic diagnostics and can explain genetic phenomena like diminished penetrance in autosomal dominant diseases. We propose that further genomic studies should focus on the single-cell level, to better understand the aetiology of aging and diseases mediated by somatic mutations.

On the relationship between pain intensity and postural sway in patients with non-specific neck pain

DEFF Research Database (Denmark)

Ruhe, Alexander; Fejer, René; Walker, Bruce

2013-01-01

Increased center of pressure excursions are well documented in patients with non-specific neck pain. While a linear relationship between pain intensity and postural sway has been described in low back pain patients, no such investigation has been conducted in adults with non-specific neck pain....

Additional Haptic Information Provided by Anchors Reduces Postural Sway in Young Adults Less Than Does Light Touch

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Renato Moraes

2018-06-01

Full Text Available This study investigated the effect of adding haptic information to the control of posture, as well as comparing the effect of both the “light touch” (LT and “anchor system” (AS paradigms on postural sway. Additionally, it compared the effect of location and number of points of contact to the control of posture in young adults. The location consisted of using the anchors tied to the finger and held by the hands, and, for LT, the fingertip. For the number of points of contact, participants used two hands, and then separately the dominant hand, and the non-dominant hand, for both anchor and LT paradigms. Participants stood upright with feet-together and in tandem position while performing tasks that combined the use of anchors and LT, points of contact (hand grip and finger, and number of points of contact (two hands and one hand. In this study, the anchors consist of holding in each hand a flexible cable with the other end attached to the ground. The LT consists of slightly touching a rigid surface with the tip of the index finger. The results showed, first, that the anchors improved postural control less than did the LT. Second, they revealed that holding the anchors with the hands or with them tied to the fingertip resulted in a similar reduction in postural sway only in the tandem position. For the feet-together position, the anchors tied to the fingertip were ineffective. Similarly, the use of one or two hands did not affect the contribution of the anchors. However, using two hands in the LT condition was more effective than was one hand. Third, our results showed the presence of a temporal delay between force and center-of-pressure (COP for the anchors, only in the AP direction with feet-together. In conclusion, overall, the anchors were less effective in reducing postural sway than was the LT. The anchors attached to fingertips were as effective as the hand-held anchors in the tandem position, yet ineffective during foot

Can explicit visual feedback of postural sway efface the effects of sensory manipulations on mediolateral balance performance?

NARCIS (Netherlands)

Cofre Lizama, L.E.; Pijnappels, M.A.G.M.; Reeves, N.P.; Verschueren, S.M.; van Dieen, J.H.

2016-01-01

Explicit visual feedback on postural sway is often used in balance assessment and training. However, up-weighting of visual information may mask impairments of other sensory systems. We therefore aimed to determine whether the effects of somatosensory, vestibular, and proprioceptive manipulations on

SeeSway - A free web-based system for analysing and exploring standing balance data.

Science.gov (United States)

Clark, Ross A; Pua, Yong-Hao

2018-06-01

Computerised posturography can be used to assess standing balance, and can predict poor functional outcomes in many clinical populations. A key limitation is the disparate signal filtering and analysis techniques, with many methods requiring custom computer programs. This paper discusses the creation of a freely available web-based software program, SeeSway (www.rehabtools.org/seesway), which was designed to provide powerful tools for pre-processing, analysing and visualising standing balance data in an easy to use and platform independent website. SeeSway links an interactive web platform with file upload capability to software systems including LabVIEW, Matlab, Python and R to perform the data filtering, analysis and visualisation of standing balance data. Input data can consist of any signal that comprises an anterior-posterior and medial-lateral coordinate trace such as center of pressure or mass displacement. This allows it to be used with systems including criterion reference commercial force platforms and three dimensional motion analysis, smartphones, accelerometers and low-cost technology such as Nintendo Wii Balance Board and Microsoft Kinect. Filtering options include Butterworth, weighted and unweighted moving average, and discrete wavelet transforms. Analysis methods include standard techniques such as path length, amplitude, and root mean square in addition to less common but potentially promising methods such as sample entropy, detrended fluctuation analysis and multiresolution wavelet analysis. These data are visualised using scalograms, which chart the change in frequency content over time, scatterplots and standard line charts. This provides the user with a detailed understanding of their results, and how their different pre-processing and analysis method selections affect their findings. An example of the data analysis techniques is provided in the paper, with graphical representation of how advanced analysis methods can better discriminate

Low back pain and postural sway during quiet standing with and without sensory manipulation: A systematic review

NARCIS (Netherlands)

Mazaheri, M.; Coenen, P.; Parnianpour, M; Kiers, H.; van Dieen, J.H.

2013-01-01

A previous review concluded that postural sway is increased in patients with low back pain (LBP). However, more detailed analysis of the literature shows that postural deficit may be dependent on experimental conditions in which patients with LBP have been assessed. The research question to be

The influence of motor imagery on postural sway: Differential effects of type of body movement and person perspective

NARCIS (Netherlands)

Stins, J.F.; Schneider, I.K.; Koole, S.L.; Beek, P.J.

2015-01-01

The present study examined the differential effects of kinesthetic imagery (first person perspective) and visual imagery (third person perspective) on postural sway during quiet standing. Based on an embodied cognition perspective, the authors predicted that kinesthetic imagery would lead to

Validation of SWAY Wind Turbine Response in FAST, with a Focus on the Influence of Tower Wind Loads: Preprint

Energy Technology Data Exchange (ETDEWEB)

Koh, J. H.; Robertson, A.; Jonkman, J.; Driscoll, R.; Yin Kwee Ng, E.

2015-04-23

Need to modify simulated system behavior to the measured data, but the tower wind loads improved the comparison for nonoperating conditions. the SWAY system in both turbine operating and nonoperating conditions. Mixed results were observed when comparing the simulated system behavior to the measured data, but the tower wind loads improved the comparison for nonoperating conditions. without the new tower-load capability to examine its influence on the response characteristics of the system. This is important in situations when the turbine is parked in survival conditions. The simulation results were then compared to measured data from the SWAY system in both turbine operating and nonoperating conditions. Mixed results were observed when comparing the simulated system behavior to the measured data, but the tower wind loads improved the comparison for nonoperating conditions.

Effects of Cable Sway, Electrode Surface Area, and Electrode Mass on Electroencephalography Signal Quality during Motion.

Science.gov (United States)

Symeonidou, Evangelia-Regkina; Nordin, Andrew D; Hairston, W David; Ferris, Daniel P

2018-04-03

More neuroscience researchers are using scalp electroencephalography (EEG) to measure electrocortical dynamics during human locomotion and other types of movement. Motion artifacts corrupt the EEG and mask underlying neural signals of interest. The cause of motion artifacts in EEG is often attributed to electrode motion relative to the skin, but few studies have examined EEG signals under head motion. In the current study, we tested how motion artifacts are affected by the overall mass and surface area of commercially available electrodes, as well as how cable sway contributes to motion artifacts. To provide a ground-truth signal, we used a gelatin head phantom with embedded antennas broadcasting electrical signals, and recorded EEG with a commercially available electrode system. A robotic platform moved the phantom head through sinusoidal displacements at different frequencies (0-2 Hz). Results showed that a larger electrode surface area can have a small but significant effect on improving EEG signal quality during motion and that cable sway is a major contributor to motion artifacts. These results have implications in the development of future hardware for mobile brain imaging with EEG.

The influence of commercial-grade carpet on postural sway and balance strategy among older adults.

Science.gov (United States)

Dickinson, Joan I; Shroyer, JoAnn L; Elias, Jeffrey W

2002-08-01

The purpose of this research study was to examine the effect of a selected commercial-grade carpet on the static balance of healthy, older adults who had not fallen more than twice in the last 6 months. We tested a total of 45 participants. Each participant stood on a computerized balance machine and was subjected to a carpeted versus a noncarpeted condition while exposed to various sensory limitations. We measured both postural sway and balance strategy. The selected commercial-grade carpet did not affect postural sway. The participants were able to adapt to the sensory limitations regardless of whether they were standing on the carpet. Although balance strategy scores were significantly lower during the carpeted conditions, the clinical significance was questionable as the difference between the means was small for practical purposes. Healthy, older adults did not have difficulty maintaining static balance on the carpeted surface; however, the results could be different if participants who had a history of falling had been included. The results from this study are important and provide a basis of comparison for those individuals who have experienced more than two falls in the last 6 months or who have a history of falling.

The Control of Posture in Newly Standing Infants is Task Dependent

Science.gov (United States)

Claxton, Laura J.; Melzer, Dawn K.; Ryu, Joong Hyun; Haddad, Jeffrey M.

2012-01-01

The postural sway patterns of newly standing infants were compared under two conditions: standing while holding a toy and standing while not holding a toy. Infants exhibited a lower magnitude of postural sway and more complex sway patterns when holding the toy. These changes suggest that infants adapt postural sway in a manner that facilitates…

A systematic review of the relationship between physical activities in sports or daily life and postural sway in upright stance.

Science.gov (United States)

Kiers, Henri; van Dieën, Jaap; Dekkers, Henk; Wittink, Harriët; Vanhees, Luc

2013-11-01

In many sports, maintaining balance is necessary to compete at a high level. Also, in many health problems, balance is impaired. Postural sway (PS) is often used as an indicator of upright balance control, and physical activity (PA) might enhance balance control. However, the relationship between PS and PA has never been systematically reviewed. Our objective was to summarize the evidence regarding the relationship between PS in upright bipedal and unipedal standing and PA. We conducted a literature search in MEDLINE, EmBase, CINAHL, the Cochrane Database, and PEDro, up to March 2012, with no limit on the starting date. Characteristics and methodological aspects of each article were extracted by two reviewers. We used centre of pressure (CoP) velocity, and variables related to the CoP area, to compare studies. A total of 39 articles were reviewed from an initial yield of 2,058. Of these 39 studies, 37 used a comparative design, one was a cohort study, and one was a randomized controlled trial. The main conclusion was that in general, sport practitioners sway less than controls, and high-level athletes sway less than low-level athletes. Additionally, we identified specific effects dependent on the use of vision, sport-specific postures, and frequency and duration of the (sports) activity. PS in unperturbed bipedal stance appears to have limited sensitivity to detect subtle differences between groups of healthy people.

Evidence for a general stiffening motor control pattern in neck pain: a cross sectional study.

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Meisingset, Ingebrigt; Woodhouse, Astrid; Stensdotter, Ann-Katrin; Stavdahl, Øyvind; Lorås, Håvard; Gismervik, Sigmund; Andresen, Hege; Austreim, Kristian; Vasseljen, Ottar

2015-03-17

Neck pain is associated with several alterations in neck motion and motor control. Previous studies have investigated single constructs of neck motor control, while few have applied a comprehensive set of tests to investigate cervical motor control. This comparative cross- sectional study aimed to investigate different motor control constructs in neck pain patients and healthy controls. A total of 166 subjects participated in the study, 91 healthy controls (HC) and 75 neck pain patients (NP) with long-lasting moderate to severe neck pain. Neck flexibility, proprioception, head steadiness, trajectory movement control, and postural sway were assessed using a 3D motion tracking system (Liberty). The different constructs of neck motion and motor control were based on tests used in previous studies. Neck flexibility was lower in NP compared to HC, indicated by reduced cervical ROM and conjunct motion. Movement velocity was slower in NP compared to HC. Tests of head steadiness showed a stiffer movement pattern in NP compared to HC, indicated by lower head angular velocity. NP patients departed less from a predictable trajectory movement pattern (figure of eight) compared to healthy controls, but there was no difference for unpredictable movement patterns (the Fly test). No differences were found for postural sway in standing with eyes open and eyes closed. However, NP patients had significantly larger postural sway when standing on a balance pad. Proprioception did not differ between the groups. Largest effect sizes (ES) were found for neck flexibility (ES range: 0.2-0.8) and head steadiness (ES range: 1.3-2.0). Neck flexibility was the only construct that showed a significant association with current neck pain, while peak velocity was the only variable that showed a significant association with kinesiophobia. NP patients showed an overall stiffer and more rigid neck motor control pattern compared to HC, indicated by lower neck flexibility, slower movement velocity

Selection of body sway parameters according to their sensitivity and repeatability

Directory of Open Access Journals (Sweden)

Nejc Sarabon

2010-03-01

Full Text Available For the precise evaluation of body balance, static type of tests performed on a force plate are the most commonly used ones. In these tests, body sway characteristics are analyzed based on the model of inverted pendulum and looking at the center of pressure (COP movement in time. Human body engages different strategies to compensate for balance perturbations. For this reason, there is a need to identify parameters which are sensitive to specific balance changes and which enable us to identify balance sub-components. The aim of our study was to investigate intra-visit repeatability and sensibility of the 40 different body sway parameters. Twenty-nine subjects participated in the study. They performed three different balancing tasks of different levels of difficulty, three repetitions each. The hip-width parallel stance and the single leg stance, both with open eyes, were used as ways to compare different balance intensities due to biomechanical changes. Additionally, deprivation of vision was used in the third balance task to study sensitivity to sensory system changes. As shown by intraclass correlation coefficient (ICC, repeatability of cumulative parameters such as COP, maximal amplitude and frequency showed excellent repeatability (ICC>0,85. Other parameters describing sub-dynamics through single repetition proved to have unsatisfying repeatability. Parameters most sensitive to increased intensity of balancing tasks were common COP, COP in medio-lateral and in antero-posterior direction, and maximal amplitues in the same directions. Frequency of oscilations has proved to be sensitive only to deprivation of vision. As shown in our study, cumulative parameters describing the path which the center of pressure makes proved to be the most repeatable and sensitive to detect different increases of balancing tasks enabling future use in balance studies and in clinical practice.

Effects of Indoor Footwear on Balance and Gait Patterns in Community-Dwelling Older Women.

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Menz, Hylton B; Auhl, Maria; Munteanu, Shannon E

2017-01-01

Footwear worn indoors is generally less supportive than outdoor footwear and may increase the risk of falls. To evaluate balance ability and gait patterns in older women while wearing different styles of indoor footwear: a backless slipper and an enclosed slipper designed to optimise balance. Older women (n = 30) aged 65-83 years (mean 74.4, SD 5.6) performed a series of laboratory tests of balance ability (postural sway, limits of stability, and tandem walking, measured with the NeuroCom® Balance Master) and gait patterns (walking speed, cadence, and step length, measured with the GAITRite® walkway) while wearing (1) socks, (2) backless slippers with a soft sole, and (3) enclosed slippers with a firm sole and Velcro® fastening. Perceptions of the footwear were also documented using a structured questionnaire. Significant overall effects of footwear were observed for postural sway, the limits of stability test (directional control), the tandem walk test (step width and end sway), and temporospatial gait patterns (walking speed, cadence, and step length). No footwear effects were observed for maximum excursion when performing the limits of stability test or for speed when performing the tandem walk test. Post hoc tests indicated that performances were best while wearing the enclosed slippers, intermediate with socks, and worst with backless slippers. The enclosed slippers were perceived to be more attractive, comfortable, and well fitted, but heavier than the backless slippers. Most participants (n = 23; 77%) reported that they would consider wearing the enclosed slippers to reduce their risk of falling. Indoor footwear with an enclosed heel, Velcro® fastening, and a firm sole optimises balance and gait compared to backless slippers, and is therefore recommended to reduce the risk of falling. © 2016 The Author(s) Published by S. Karger AG, Basel.

The effects of arm crank ergometry, cycle ergometry and treadmill walking on postural sway in healthy older females.

Science.gov (United States)

Hill, M W; Oxford, S W; Duncan, M J; Price, M J

2015-01-01

Older adults are increasingly being encouraged to exercise but this may lead to muscle fatigue, which can adversely affect postural stability. Few studies have investigated the effects of upper body exercise on postural sway in groups at risk of falling, such as the elderly. The purpose of this study was to compare the effects arm crank ergometry (ACE), cycle ergometry (CE) and treadmill walking (TM) on postural sway in healthy older females. In addition, this study sought to determine the time necessary to recover postural control after exercise. A total of nine healthy older females participated in this study. Participants stood on a force platform to assess postural sway which was measured by displacement of the centre of pressure before and after six separate exercise trials. Each participant completed three incremental exercise tests to 85% of individual's theoretical maximal heart rate (HRMAX) for ACE, CE and TM. Subsequent tests involved 20-min of ACE, CE and TM exercise at a relative workload corresponding to 50% of each individual's predetermined heart rate reserve (HRE). Post fatigue effects and postural control recovery were measured at different times after exercise (1, 3, 5, 10, 15 and 30-min). None of the participants exhibited impaired postural stability after ACE. In contrast, CE and TM elicited significant post exercise balance impairments, which lasted for ∼ 10 min post exercise. We provide evidence of an exercise mode which does not elicit post exercise balance impairments. Older adults should exercise caution immediately following exercise engaging the lower limbs to avoid fall risk. Copyright © 2014 Elsevier B.V. All rights reserved.

Tonic immobility differentiates stress responses in PTSD.

Science.gov (United States)

Fragkaki, Iro; Stins, John; Roelofs, Karin; Jongedijk, Ruud A; Hagenaars, Muriel A

2016-11-01

Tonic immobility (TI) is a state of physical immobility associated with extreme stress and the development of posttraumatic stress disorder (PTSD). However, it is unknown whether TI is associated with a distinct actual stress response, i.e., objective immobility measured by a stabilometric platform. This study made a first step in exploring this as well as differences in body sway responses between PTSD patients and healthy controls. We hypothesized that PTSD would be related to increased body sway under stress, whereas TI would be related to decreased body sway under stress. Eye closure was selected as a PTSD-relevant stress induction procedure. Body sway and heart rate (HR) were measured in 12 PTSD patients and 12 healthy controls in four conditions: (1) maintaining a stable stance with eyes open, (2) with eyes closed, (3) during a mental arithmetic task with eyes open, and (4) with eyes closed. As predicted, PTSD patients showed increased body sway from eyes open to eyes closed compared to controls and this effect was eliminated by executing the arithmetic task. Most importantly, retrospective self-reported TI was associated with lower body sway increases in PTSD and higher body sway decreases in controls from eyes-open to eyes-closed conditions. These preliminary findings suggest that eye closure has a different effect on PTSD patients than controls and that high self-reported TI might indicate a distinct stress response pattern, i.e., a proneness for immobility. It may be relevant to take such individual differences in stress-response into account in PTSD treatment.

SENSITIVITY OF BODY SWAY PARAMETERS DURING QUIET STANDING TO MANIPULATION OF SUPPORT SURFACE SIZE

Directory of Open Access Journals (Sweden)

Sarabon Nejc

2010-09-01

Full Text Available The centre of pressure (COP movement during stance maintenance on a stable surface is commonly used to describe and evaluate static balance. The aim of our study was to test sensitivity of individual COP parameters to different stance positions which were used to address size specific changes in the support surface. Twenty-nine subjects participated in the study. They carried out three 60-second repetitions of each of the five balance tasks (parallel stance, semi-tandem stance, tandem stance, contra-tandem stance, single leg stance. Using the force plate, the monitored parameters included the total COP distance, the distance covered in antero-posterior and medio-lateral directions, the maximum oscillation amplitude in antero-posterior and medio-lateral directions, the total frequency of oscillation, as well as the frequency of oscillation in antero-posterior and medio-lateral directions. The parameters which describe the total COP distance were the most sensitive to changes in the balance task, whereas the frequency of oscillation proved to be sensitive to a slightly lesser extent. Reductions in the support surface size in each of the directions resulted in proportional changes of antero-posterior and medio- lateral directions. The frequency of oscillation did not increase evenly with the increase in the level of difficulty of the balance task, but reached a certain value, above which it did not increase. Our study revealed the monitored parameters of the COP to be sensitive to the support surface size manipulations. The results of the study provide an important source for clinical and research use of the body sway measurements.

Sway Area and Velocity Correlated With MobileMat Balance Error Scoring System (BESS) Scores.

Science.gov (United States)

Caccese, Jaclyn B; Buckley, Thomas A; Kaminski, Thomas W

2016-08-01

The Balance Error Scoring System (BESS) is often used for sport-related concussion balance assessment. However, moderate intratester and intertester reliability may cause low initial sensitivity, suggesting that a more objective balance assessment method is needed. The MobileMat BESS was designed for objective BESS scoring, but the outcome measures must be validated with reliable balance measures. Thus, the purpose of this investigation was to compare MobileMat BESS scores to linear and nonlinear measures of balance. Eighty-eight healthy collegiate student-athletes (age: 20.0 ± 1.4 y, height: 177.7 ± 10.7 cm, mass: 74.8 ± 13.7 kg) completed the MobileMat BESS. MobileMat BESS scores were compared with 95% area, sway velocity, approximate entropy, and sample entropy. MobileMat BESS scores were significantly correlated with 95% area for single-leg (r = .332) and tandem firm (r = .474), and double-leg foam (r = .660); and with sway velocity for single-leg (r = .406) and tandem firm (r = .601), and double-leg (r = .575) and single-leg foam (r = .434). MobileMat BESS scores were not correlated with approximate or sample entropy. MobileMat BESS scores were low to moderately correlated with linear measures, suggesting the ability to identify changes in the center of mass-center of pressure relationship, but not higher-order processing associated with nonlinear measures. These results suggest that the MobileMat BESS may be a clinically-useful tool that provides objective linear balance measures.

Interwoven fluctuations during intermodal perception: fractality in head sway supports the use of visual feedback in haptic perceptual judgments by manual wielding.

Science.gov (United States)

Kelty-Stephen, Damian G; Dixon, James A

2014-12-01

Intermodal integration required for perceptual learning tasks is rife with individual differences. Participants vary in how they use perceptual information to one modality. One participant alone might change her own response over time. Participants vary further in their use of feedback through one modality to inform another modality. Two experiments test the general hypothesis that perceptual-motor fluctuations reveal both information use within modality and coordination among modalities. Experiment 1 focuses on perceptual learning in dynamic touch, in which participants use exploratory hand-wielding of unseen objects to make visually guided length judgments and use visual feedback to rescale their judgments of the same mechanical information. Previous research found that the degree of fractal temporal scaling (i.e., "fractality") in hand-wielding moderates the use of mechanical information. Experiment 1 shows that head-sway fractality moderates the use of visual information. Further, experience with feedback increases head-sway fractality and prolongs its effect on later hand-wielding fractality. Experiment 2 replicates effects of head-sway fractality moderating use of visual information in a purely visual-judgment task. Together, these findings suggest that fractal fluctuations may provide a modal-general window onto not just how participants use perceptual information but also how well they may integrate information among different modalities. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Stable Chimeras and Independently Synchronizable Clusters

Science.gov (United States)

Cho, Young Sul; Nishikawa, Takashi; Motter, Adilson E.

2017-08-01

Cluster synchronization is a phenomenon in which a network self-organizes into a pattern of synchronized sets. It has been shown that diverse patterns of stable cluster synchronization can be captured by symmetries of the network. Here, we establish a theoretical basis to divide an arbitrary pattern of symmetry clusters into independently synchronizable cluster sets, in which the synchronization stability of the individual clusters in each set is decoupled from that in all the other sets. Using this framework, we suggest a new approach to find permanently stable chimera states by capturing two or more symmetry clusters—at least one stable and one unstable—that compose the entire fully symmetric network.

A systematic review of the relationship between physical activities in sports or daily life and postural sway in upright stance

NARCIS (Netherlands)

Kiers, H.; van Dieen, J.H.; Dekkers, H.; Wittink, H.; Vanhees, L.

2013-01-01

Background: In many sports, maintaining balance is necessary to compete at a high level. Also, in many health problems, balance is impaired. Postural sway (PS) is often used as an indicator of upright balance control, and physical activity (PA) might enhance balance control. However, the

A longitudinal assessment of myoelectric activity, postural sway, and low-back pain during pregnancy.

Science.gov (United States)

Moreira, Luciana S; Elias, Leonardo A; Gomide, Adriane B; Vieira, Marcus F; DO Amaral, Waldemar N

2017-01-01

The present study aimed at investigating the control of upright quiet standing in pregnant women throughout pregnancy, and whether low-back pain exerts influence on this motor task. Myoelectric signals from postural muscles and stabilometric data were collected from 15 non-pregnant and 15 pregnant women during upright quiet standing. Electromyogram envelopes and center of pressure metrics were evaluated in the control group, as well as in pregnant women in their first and third trimester of pregnancy. A correlation analysis was performed between the measured variables and a low-back pain disability index. Pregnant women exhibited a decreased maximum voluntary isometric activity for all postural muscles evaluated. Additionally, the activity of lumbar muscles during the postural task was significantly higher in the pregnant women in comparison to the non-pregnant controls. The soleus muscle maintained its activity at the same level as the gestation progressed. Higher postural oscillations were observed in the anteroposterior direction while mediolateral sway was reduced in the third trimester of pregnancy. No correlation was detected between the lowback pain disability index and neuromechanical variables. This study provides additional data regarding the functioning and adaptations of the postural control system during pregnancy. Also, we provide further evidence that postural control during quiet standing cannot be used to predict the occurrence of low-back pain. We hypothesize that the modifications in the neural drive to the muscles, as well as in postural sway may be related to changes in the biomechanics and hormonal levels experienced by the pregnant women.

Patterning characteristics of a chemically-amplified negative resist in synchrotron radiation lithography

International Nuclear Information System (INIS)

Deguchi, Kimiyoshi; Miyoshi, Kazunori; Ishii, Tetsuyoshi; Matsuda, Tadahito

1992-01-01

To explore the applicability of synchrotron radiation X-ray lithography for fabricating sub-quartermicron devices, we investigate the patterning characteristics of the chemically-amplified negative resist SAL601-ER7. Since these characteristics depend strongly on the conditions of the chemical amplification process, the effects of post-exposure baking and developing conditions on sensitivity and resolution are examined. The resolution-limiting factors are investigated, revealing that pattern collapse during the development process and fog caused by Fresnel diffraction, photo-electron scattering, and acid diffusion in the resist determine the resolution and the maximum aspect ratio of the lines and spaces pattern. Using the model of a swaying beam supported at one end, it is shown that pattern collapse depends on the resist pattern's flexural stiffness. Patterning stability, which depends on the delay time between exposure and baking, is also discussed. (author)

Sway control method and system for rotary cranes

Science.gov (United States)

Robinett, Rush D.; Parker, Gordon G.; Feddema, John T.; Dohrmann, Clark R.; Petterson, Ben J.

1999-01-01

Methods and apparatuses for reducing the oscillatory motion of rotary crane payloads during operator-commanded or computer-controlled maneuvers. An Input-shaping filter receives input signals from multiple operator input devices and converts them into output signals readable by the crane controller to dampen the payload tangential and radial sway associated with rotation of the jib. The input signals are characterized by a hub rotation trajectory .gamma.(t), which includes a jib angular acceleration .gamma., a trolley acceleration x, and a load-line length velocity L. The system state variables are characterized by a tangential rotation angle .theta.(t) and a radial rotation angle .phi.(t) of the load-line. The coupled equations of motion governing the filter are non-linear and configuration-dependent. In one embodiment, a filter is provided between the operator and the crane for filtering undesired frequencies from the angular .gamma. and trolley x velocities to suppress payload oscillation. In another embodiment, crane commands are computer generated and controlled to suppress vibration of the payload using a postulated asymmetrical shape for the acceleration profiles of the jib, which profiles are uniquely determined by a set of parameters (including the acceleration pulse amplitude and the duration and coast time between pulses), or a dynamic programming approach.

Suppression of Transient Events by Levitation (STABLE): Results From the USML-2 Mission. Experiment 38

Science.gov (United States)

Nurre, Gerald S.; Edberg, Donald L.

1998-01-01

Microgravity science payloads can be extremely sensitive to vibrations from machinery, acoustics, ventilation, and crew activity. Suppression of Transient Acceleration by Levitation (STABLE) is an active vibration isolation system designed to protect payloads from these disturbances. This paper gives an account of results from the flight demonstration of the STABLE microgravity isolation system, which was developed and successfully flight tested in orbit during USML-2, with the participation of Astronaut Fred Leslie. Following a very brief description of the operational principles, the hardware and software design, and performance criteria, results of the analysis of measured flight data are presented to provide an evaluation of system performance parameters, including acceleration attenuation, assessment of sway space, system power consumption, and other factors critical to the performance of an isolation system. Lessons learned and potential design improvements and evolutions are discussed. Data reduction by Robert Boucher of McDonnell Douglas Aerospace (MDA) was substantially assisted by Kenneth Hrovat of Tal-Cut, Inc., under support from National Aeronautics and Space Administration/Lewis Research Center (LeRC), Cleveland, OH.

Influence of the visual environment on the postural stability in healthy older women.

Science.gov (United States)

Brooke-Wavell, K; Perrett, L K; Howarth, P A; Haslam, R A

2002-01-01

A poor postural stability in older people is associated with an increased risk of falling. It is recognized that visual environment factors (such as poor lighting and repeating patterns on escalators) may contribute to falls, but little is known about the effects of the visual environment on postural stability in the elderly. To determine whether the postural stability of older women (using body sway as a measure) differed under five different visual environment conditions. Subjects were 33 healthy women aged 65-76 years. Body sway was measured using an electronic force platform which identified the location of their centre of gravity every 0.05 s. Maximal lateral sway and anteroposterior sway were determined and the sway velocity calculated over 1-min trial periods. Body sway was measured under each of the following conditions: (1) normal laboratory lighting (186 lx); (2) moderate lighting (10 lx); (3) dim lighting (1 lx); (4) eyes closed, and (5) repeating pattern projected onto a wall. Each measure of the postural stability was significantly poorer in condition 4 (eyes closed) than in all other conditions. Anteroposterior sway was greater in condition 3 than in conditions 1 and 2, whilst the sway velocity was greater in condition 3 than in condition 2. Lateral sway did not differ significantly between different lighting levels (conditions 1-3). A projected repeating pattern (condition 5) did not significantly influence the postural stability relative to condition 1. The substantially greater body sway with eyes closed than with eyes open confirms the importance of vision in maintaining the postural stability. At the lowest light level, the body sway was significantly increased as compared with the other light levels, but was still substantially smaller than on closing the eyes. A projected repeating pattern did not influence the postural stability. Dim lighting levels and removing visual input appear to be associated with a poorer postural stability in older

Direct printing of patterned three-dimensional ultrafine fibrous scaffolds by stable jet electrospinning for cellular ingrowth

International Nuclear Information System (INIS)

Yuan, Huihua; Zhou, Qihui; Li, Biyun; Bao, Min; Lou, Xiangxin; Zhang, Yanzhong

2015-01-01

Electrospinning has been widely used to produce ultrafine fibers in microscale and nanoscale; however, traditional electrospinning processes are currently beset by troublesome limitations in fabrication of 3D periodic porous structures because of the chaotic nature of the electrospinning jet. Here we report a novel strategy to print 3D poly(L-lactic acid) (PLLA) ultrafine fibrous scaffolds with the fiber diameter of approximately 2 μm by combining a stable jet electrospinning method and an X-Y stage technique. Our approach allows linearly deposited electrospun ultrafine fibers to assemble into 3D structures with tunable pore sizes and desired patterns. Process conditions (e.g., plotting speed, feeding rate, and collecting distance) were investigated in order to achieve stable jet printing of ultrafine PLLA fibers. The proposed 3D scaffold was successfully used for cell penetration and growth, demonstrating great potential for tissue engineering applications. (paper)

Postural sway changes during pregnancy: a descriptive study using stabilometry.

Science.gov (United States)

Oliveira, Liliam F; Vieira, Taian M M; Macedo, Adriana R; Simpson, David M; Nadal, Jurandir

2009-11-01

This study aims to analyse changes in body sway over the course of pregnancy. This is a descriptive study in which stabilometric tests were applied at three stages of pregnancy and with a combination of different visual conditions (eyes open/closed) and support base configuration (feet together/apart). Twenty healthy pregnant women participated in the study. Changes in postural control with pregnancy were analysed via the elliptical area of the stabilograms and spectral analysis of the displacements of the centre of pressure (COP) along the lateral and anterior/posterior directions. The elliptical area encompassing the COP significantly increased over the course of the pregnancy for the feet apart and eyes closed test protocols. The spectral analysis revealed a significant increase of COP oscillations along the anterior-posterior direction when subjects stood with the eyes open/feet together and feet apart. A reduction (significant) of the lateral oscillations of COP was observed for the eyes open/feet together protocol. Pregnancy induced significant changes in the postural control when pregnant women stood with a reduced support base or with eyes closed.

Temperature and Humidity Control in Livestock Stables

DEFF Research Database (Denmark)

Hansen, Michael; Andersen, Palle; Nielsen, Kirsten M.

2010-01-01

The paper describes temperature and humidity control of a livestock stable. It is important to have a correct air flow pattern in the livestock stable in order to achieve proper temperature and humidity control as well as to avoid draught. In the investigated livestock stable the air flow...

Application of stable isotopes and isotope pattern deconvolution-ICPMS to speciation of endogenous and exogenous Fe and Se in rats

International Nuclear Information System (INIS)

Gonzalez Iglesias, H.; Fernandez-Sanchez, M.L.; Garcia Alonso, J.I.; Lopez Sastre, J.B.; Sanz-Medel, A.

2009-01-01

Full text: Enriched stable isotopes are crucial to study essential trace element metabolism (e.g. Se, Fe) in biological systems. Measuring isotope ratios by ICPMS and using appropriate mathematical calculations, based on isotope pattern deconvolution (IPD) may provide quantitative data about endogenous and exogenous essential or toxic elements and their metabolism. In this work, IPD was applied to explore the feasibility of using two Se (or Fe) enriched stable isotopes, one as metabolic tracer and the other as quantitation tracer, to discriminate between the endogenous and supplemented Se (or Fe) species in rat fluids by collision cell ICPMS coupled to HPLC separation. (author)

Effects of body weight-support treadmill training on postural sway and gait independence in patients with chronic spinal cord injury.

Science.gov (United States)

Covarrubias-Escudero, Felipe; Rivera-Lillo, Gonzalo; Torres-Castro, Rodrigo; Varas-Díaz, Gonzalo

2017-10-23

To examine the effects of a six-week body weight-support treadmill training (BWSTT) program on center-of-mass control and gait independence in chronic, incomplete spinal cord injury (iSCI) patients. Descriptive. Clinica Los Coihues. Neurorehabilitation center in Santiago, Chile. 17 chronic iSCI patients and 17 healthy subjects. An instrumented sway (ISway) test was performed before and after the implementation of a six-week BWSTT program. The standing balance of participants was measured by Normalized jerk (NJ) and root mean square (RMS). These values were used to assess the standing balance of participants, and were correlated with the scores obtained on the Walking Index Spinal Cord Injury (WISCI) II test. Significant differences were found in standing balance (i.e., through NJ) after the BWSTT program (P = 0.016), but no significant differences were found in RMS values for postural sway (P = 0.693). None of the patients obtained improved WISCI II scores pre- vs. post-intervention. While a BWSTT program can improve center-of-mass control in iSCI patients, no effects were recorded for gait independence. National Clinical Trials, registry number NCT02703883.

Plant Water Use Strategy in Response to Spatial and Temporal Variation in Precipitation Patterns in China: A Stable Isotope Analysis

Directory of Open Access Journals (Sweden)

Ying Zhao

2018-03-01

Full Text Available Spatial and temporal variation in precipitation patterns can directly alter the survival and growth of plants, yet in China there is no comprehensive and systematic strategy for plant use based on the effects of precipitation patterns. Here, we examined information from 93 published papers (368 plant species on plant xylem water stable isotopes (δD and δ18O in China. The results showed that: (1 The slope of the local meteoric water line (LMWL gradually increased from inland areas to the coast, as a result of continental and seasonal effects. The correlation between δD and δ18O in plant stem water is also well fitted and the correlation coefficients range from 0.78 to 0.89. With respect to the soil water line, the δ18O values in relation to depth (0–100 cm varied over time; (2 Plants’ main water sources are largely affected by precipitation patterns. In general, plants prioritize the use of stable and continuous water sources, while they have a more variable water uptake strategy under drought conditions; (3 There are no spatial and temporal variations in the contribution of the main water source (p > 0.05 because plants maintain growth by shifting their use of water sources when resources are unreliable.

Mapping Precipitation Patterns from the Stable Isotopic Composition of Surface Waters: Olympic Peninsula, Washington State

Science.gov (United States)

Anders, A. M.; Brandon, M. T.

2008-12-01

Available data indicate that large and persistent precipitation gradients are tied to topography at scales down to a few kilometers, but precipitation patterns in the majority of mountain ranges are poorly constrained at scales less than tens of kilometers. A lack of knowledge of precipitation patterns hampers efforts to understand the processes of orographic precipitation and identify the relationships between geomorphic evolution and climate. A new method for mapping precipitation using the stable isotopic composition of surface waters is tested in the Olympic Mountains of Washington State. Measured δD and δ18O of 97 samples of surface water are linearly related and nearly inseparable from the global meteoric water line. A linear orographic precipitation model extended to include in effects of isotopic fractionation via Rayleigh distillation predicts precipitation patterns and isotopic composition of surface water. Seven parameters relating to the climate and isotopic composition of source water are used. A constrained random search identifies the best-fitting parameter set. Confidence intervals for parameter values are defined and precipitation patterns are determined. Average errors for the best-fitting model are 4.8 permil in δD. The difference between the best fitting model and other models within the 95% confidence interval was less than 20%. An independent high-resolution precipitation climatology documents precipitation gradients similar in shape and magnitude to the model derived from surface water isotopic composition. This technique could be extended to other mountain ranges, providing an economical and fast assessment of precipitation patterns requiring minimal field work.

Investigating the center of pressure velocity Romberg's quotient for assessing the visual role on the body sway

OpenAIRE

Silva, Paulo José Guimarães da; Nadal, Jurandir; Infantosi, Antonio Fernando Catelli

2012-01-01

The classical Romberg's test based on stabilometric tests in eyes open (EO) and closed (EC) conditions was used for investigating the influence of visual feedback in the body sway control in healthy adult subjects. Stabilograms from 144 subjects (aged 18-40) resting over a force platform were recorded for 30 s in EO and 30 s in EC conditions. The mean velocity was obtained for EO (VmEO) and EC (VmEC) in both anterior-posterior (y) and medial-lateral (x) directions and in the (x,y) plane, and ...

Forensic Stable Isotope Biogeochemistry

Science.gov (United States)

Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

2016-06-01

Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

Globally Stable Microresonator Turing Pattern Formation for Coherent High-Power THz Radiation On-Chip

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Huang, Shu-Wei; Yang, Jinghui; Yang, Shang-Hua; Yu, Mingbin; Kwong, Dim-Lee; Zelevinsky, T.; Jarrahi, Mona; Wong, Chee Wei

2017-10-01

In nonlinear microresonators driven by continuous-wave (cw) lasers, Turing patterns have been studied in the formalism of the Lugiato-Lefever equation with emphasis on their high coherence and exceptional robustness against perturbations. Destabilization of Turing patterns and the transition to spatiotemporal chaos, however, limit the available energy carried in the Turing rolls and prevent further harvest of their high coherence and robustness to noise. Here, we report a novel scheme to circumvent such destabilization, by incorporating the effect of local mode hybridizations, and we attain globally stable Turing pattern formation in chip-scale nonlinear oscillators with significantly enlarged parameter space, achieving a record-high power-conversion efficiency of 45% and an elevated peak-to-valley contrast of 100. The stationary Turing pattern is discretely tunable across 430 GHz on a THz carrier, with a fractional frequency sideband nonuniformity measured at 7.3 ×10-14 . We demonstrate the simultaneous microwave and optical coherence of the Turing rolls at different evolution stages through ultrafast optical correlation techniques. The free-running Turing-roll coherence, 9 kHz in 200 ms and 160 kHz in 20 minutes, is transferred onto a plasmonic photomixer for one of the highest-power THz coherent generations at room temperature, with 1.1% optical-to-THz power conversion. Its long-term stability can be further improved by more than 2 orders of magnitude, reaching an Allan deviation of 6 ×10-10 at 100 s, with a simple computer-aided slow feedback control. The demonstrated on-chip coherent high-power Turing-THz system is promising to find applications in astrophysics, medical imaging, and wireless communications.

Anamnestic prediction of bucket handle compared to other tear patterns of the medial meniscus in stable knees.

Science.gov (United States)

Haviv, Barak; Bronak, Shlomo; Kosashvili, Yona; Thein, Rafael

2016-12-01

The aim of this study was to analyze and compare the preoperative anamnestic details between patients with an arthroscopic diagnosis of bucket handle and other tear patterns of the medial meniscus in stable knees. A total of 204 patients (mean age 49.3 ± 13 years) were included in the study. The mean age was 49.3 ± 13 years. The study group included 65 patients (63 males, 2 females) with an arthroscopic diagnosis of bucket handle tear and the control group included 139 patients (90 males, 49 females) with non-bucket handle tear patterns. The preoperative clinical assessments of the two groups were analyzed retrospectively. Anamnestic prediction for the diagnosis of a bucket handle tear was based upon various medical history parameters. Multivariate logistic regression was carried out to identify independent anamnestic factors for predicting isolated bucket handle tears of the medial meniscus compared to non-bucket handle tears. Analysis of the multivariate logistic regression yielded 3 statistically significant independent anamnestic risk factors for predicting isolated bucket handle tears of the medial meniscus: male gender (OR, 9.7; 95% CI, 1.1-37.6), locking events (OR, 4.6; 95% CI, 1.8-11.3) and pain in extension (OR, 6.9; 95% CI, 2.5-23.7). Other preoperative variables such as age, BMI, activity level, comorbidities, duration of symptoms, pain location, preceding injury and its mechanism had no significant effect on tear pattern. Preoperative strong clues for bucket handle tears of the medial meniscus in stable knees are male gender, locking events and limitation in extension. Level III, Diagnostic study. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Nintendo Wii Balance Board is sensitive to effects of visual tasks on standing sway in healthy elderly adults.

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Koslucher, Frank; Wade, Michael G; Nelson, Brent; Lim, Kelvin; Chen, Fu-Chen; Stoffregen, Thomas A

2012-07-01

Research has shown that the Nintendo Wii Balance Board (WBB) can reliably detect the quantitative kinematics of the center of pressure in stance. Previous studies used relatively coarse manipulations (1- vs. 2-leg stance, and eyes open vs. closed). We sought to determine whether the WBB could reliably detect postural changes associated with subtle variations in visual tasks. Healthy elderly adults stood on a WBB while performing one of two visual tasks. In the Inspection task, they maintained their gaze within the boundaries of a featureless target. In the Search task, they counted the occurrence of designated target letters within a block of text. Consistent with previous studies using traditional force plates, the positional variability of the center of pressure was reduced during performance of the Search task, relative to movement during performance of the Inspection task. Using detrended fluctuation analysis, a measure of movement dynamics, we found that COP trajectories were more predictable during performance of the Search task than during performance of the Inspection task. The results indicate that the WBB is sensitive to subtle variations in both the magnitude and dynamics of body sway that are related to variations in visual tasks engaged in during stance. The WBB is an inexpensive, reliable technology that can be used to evaluate subtle characteristics of body sway in large or widely dispersed samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Transition of spiral calcium waves between multiple stable patterns can be triggered by a single calcium spark in a fire-diffuse-fire model

Science.gov (United States)

Tang, Ai-Hui; Wang, Shi-Qiang

2009-01-01

Spiral patterns have been found in various nonequilibrium systems. The Ca2+-induced Ca2+ release system in single cardiac cells is unique for highly discrete reaction elements, each giving rise to a Ca2+ spark upon excitation. We imaged the spiral Ca2+ waves in isolated cardiac cells and numerically studied the effect of system excitability on spiral patterns using a two-dimensional fire-diffuse-fire model. We found that under certain conditions, the system was able to display multiple stable patterns of spiral waves, each exhibiting different periods and distinct routines of spiral tips. Transition between these different patterns could be triggered by an internal fluctuation in the form of a single Ca2+ spark. PMID:19792039

Transition of spiral calcium waves between multiple stable patterns can be triggered by a single calcium spark in a fire-diffuse-fire model.

Science.gov (United States)

Tang, Ai-Hui; Wang, Shi-Qiang

2009-09-01

Spiral patterns have been found in various nonequilibrium systems. The Ca(2+)-induced Ca(2+) release system in single cardiac cells is unique for highly discrete reaction elements, each giving rise to a Ca(2+) spark upon excitation. We imaged the spiral Ca(2+) waves in isolated cardiac cells and numerically studied the effect of system excitability on spiral patterns using a two-dimensional fire-diffuse-fire model. We found that under certain conditions, the system was able to display multiple stable patterns of spiral waves, each exhibiting different periods and distinct routines of spiral tips. Transition between these different patterns could be triggered by an internal fluctuation in the form of a single Ca(2+) spark.

Cross-Modal Calibration of Vestibular Afference for Human Balance.

Directory of Open Access Journals (Sweden)

Martin E Héroux

Full Text Available To determine how the vestibular sense controls balance, we used instantaneous head angular velocity to drive a galvanic vestibular stimulus so that afference would signal that head movement was faster or slower than actual. In effect, this changed vestibular afferent gain. This increased sway 4-fold when subjects (N = 8 stood without vision. However, after a 240 s conditioning period with stable balance achieved through reliable visual or somatosensory cues, sway returned to normal. An equivalent galvanic stimulus unrelated to sway (not driven by head motion was equally destabilising but in this situation the conditioning period of stable balance did not reduce sway. Reflex muscle responses evoked by an independent, higher bandwidth vestibular stimulus were initially reduced in amplitude by the galvanic stimulus but returned to normal levels after the conditioning period, contrary to predictions that they would decrease after adaptation to increased sensory gain and increase after adaptation to decreased sensory gain. We conclude that an erroneous vestibular signal of head motion during standing has profound effects on balance control. If it is unrelated to current head motion, the CNS has no immediate mechanism of ignoring the vestibular signal to reduce its influence on destabilising balance. This result is inconsistent with sensory reweighting based on disturbances. The increase in sway with increased sensory gain is also inconsistent with a simple feedback model of vestibular reflex action. Thus, we propose that recalibration of a forward sensory model best explains the reinterpretation of an altered reafferent signal of head motion during stable balance.

Traditional Chinese medicine for stable angina pectoris via TCM pattern differentiation and TCM mechanism: study protocol of a randomized controlled trial.

Science.gov (United States)

Zhang, Zhe; Zhang, Fan; Wang, Yang; Du, Yi; Zhang, Huiyong; Kong, Dezhao; Liu, Yue; Yang, Guanlin

2014-10-30

Stable angina pectoris is experienced as trans-sternal or retro-sternal pressure or pain that may radiate to the left arm, neck or back. Although available evidence relating to its effectiveness and mechanism are weak, traditional Chinese medicine is used as an alternative therapy for stable angina pectoris. We report a protocol of a randomized controlled trial using traditional Chinese medicine to investigate the effectiveness, mechanism and safety for patients with stable angina pectoris. This is a north-east Chinese, multi-center, multi-blinded, placebo-controlled and superiority randomized trail. A total of 240 patients with stable angina pectoris will be randomly assigned to three groups: two treatment groups and a control group. The treatment groups will receive Chinese herbal medicine consisting of Yi-Qi-Jian-Pi and Qu-Tan-Hua-Zhuo granule and Yi-Qi-Jian-Pi and Qu-Tan-Hua-Yu granule, respectively, and conventional medicine. The control group will receive placebo medicine in addition to conventional medicine. All 3 groups will undergo a 12-week treatment and 2-week follow-up. Four visits in sum will be scheduled for each subject: 1 visit each in week 0, week 4, week 12 and week 14. The primary outcomes include: the frequency of angina pectoris attack; the dosage of nitroglycerin; body limited dimension of Seattle Angina Questionnaire. The secondary outcomes include: except for the body limited dimension of SAQ, traditional Chinese medicine pattern questionnaire and so on. Therapeutic mechanism outcomes, safety outcomes and endpoint outcomes will be also assessed. The primary aim of this trial is to develop a standard protocol to utilize high-quality EBM evidence for assessing the effectiveness and safety of SAP via TCM pattern differentiation as well as exploring the efficacy mechanism and regulation with the molecular biology and systems biology. ChiCTR-TRC-13003608, registered 18 June 2013.

Origin of dolomites in a downslope biostrome, Jefferson Formation (Frasnian), central Idaho: evidence from REE patterns, stable isotopes, and petrography

Energy Technology Data Exchange (ETDEWEB)

Dorobek, S.L.

1987-08-01

A completely dolomitized coral-stromatoporoid biostrome occurs at the top of the Dark Dolomite member of the Jefferson Formation (Frasnian) at Grandview Canyon, Lost River Range, central Idaho. The biostrome overlies a thick sequence of dolostones that were deposited in slope to deep ramp settings. The biostrome, therefore, formed in an open marine setting after shallowing of deep water environments. Zoned dolospar cement fills dissolution vugs and tectonic fractures. Stable isotopes for zoned dolospar are -13.1 to -6.5 per thousand delta/sup 18/O (average - 11.5) and -1.5 to -0.1 per thousand delta/sup 13/C (average -0.4). REE patterns for zoned dolospar have positive Ce anomalies, but total REE abundance is similar to REE abundance for replacive dolomites. Stratigraphic occurrence in an open marine setting, stable isotopes, and REE patterns suggest replacive dolomite phases formed during shallow burial diagenesis with significant involvement of nonevaporated sea water. More negative Ce anomalies near the top of the biostrome suggest a diagenetic overprint by oxidizing meteoric waters. Zoned dolospar probably formed from warmer, reducing burial fluids. Carbon for zoned dolospar probably was recycled from preexisting dolomite. These data may be useful for interpreting the origin of other anomalous platform dolostones.

The development of patterns of stable, transient, and school-age onset aggressive behavior in young children.

Science.gov (United States)

Kingston, L; Prior, M

1995-03-01

To examine the development of patterns of aggressive behavior in children from the age of 2 to 8 years. Children with early histories of aggressive behavior were selected from a community sample of 2,400 infants participating in a longitudinal study. The sample was divided into four groups: children with stable aggressive behavior, those with transient aggression, those with aggression only after age 5 years (late onset), and a comparison group of nonaggressive children. Children with stable aggressive behavior were characterized by a difficult temperament, hostile sibling interactions, maternal perception of the child as difficult, and harsher child-rearing practices. Children whose early aggression decreased over time and those who became aggressive only after entering school could not be reliably classified with the selected family variables. Teacher ratings of temperament factors of task orientation and reactivity and ability ratings correctly classified 74% of children whose aggression began at school-age. Children with persistent aggressive behavior differed from those who improved, predominantly in terms of symptom severity. Problems with aggression can be identified early in development, and a significant proportion of aggressive children are at risk for continuing social and scholastic difficulties. Knowledge of associated factors may play an important role in prevention.

Are clusters of dietary patterns and cluster membership stable over time? Results of a longitudinal cluster analysis study.

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Walthouwer, Michel Jean Louis; Oenema, Anke; Soetens, Katja; Lechner, Lilian; de Vries, Hein

2014-11-01

Developing nutrition education interventions based on clusters of dietary patterns can only be done adequately when it is clear if distinctive clusters of dietary patterns can be derived and reproduced over time, if cluster membership is stable, and if it is predictable which type of people belong to a certain cluster. Hence, this study aimed to: (1) identify clusters of dietary patterns among Dutch adults, (2) test the reproducibility of these clusters and stability of cluster membership over time, and (3) identify sociodemographic predictors of cluster membership and cluster transition. This study had a longitudinal design with online measurements at baseline (N=483) and 6 months follow-up (N=379). Dietary intake was assessed with a validated food frequency questionnaire. A hierarchical cluster analysis was performed, followed by a K-means cluster analysis. Multinomial logistic regression analyses were conducted to identify the sociodemographic predictors of cluster membership and cluster transition. At baseline and follow-up, a comparable three-cluster solution was derived, distinguishing a healthy, moderately healthy, and unhealthy dietary pattern. Male and lower educated participants were significantly more likely to have a less healthy dietary pattern. Further, 251 (66.2%) participants remained in the same cluster, 45 (11.9%) participants changed to an unhealthier cluster, and 83 (21.9%) participants shifted to a healthier cluster. Men and people living alone were significantly more likely to shift toward a less healthy dietary pattern. Distinctive clusters of dietary patterns can be derived. Yet, cluster membership is unstable and only few sociodemographic factors were associated with cluster membership and cluster transition. These findings imply that clusters based on dietary intake may not be suitable as a basis for nutrition education interventions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects on muscle strength, maximal jump height, flexibility and postural sway after soccer and Zumba exercise among female hospital employees: a 9-month randomised controlled trial.

Science.gov (United States)

Barene, Svein; Holtermann, Andreas; Oseland, Harald; Brekke, Ole-Lars; Krustrup, Peter

2016-10-01

This 9-month randomised controlled workplace physical activity trial investigated the effects of soccer and Zumba exercise, respectively, on muscle strength, maximal jump height, sit-and-reach flexibility and postural sway among female workers. A total of 107 female hospital employees aged 25-63 were cluster-randomised to a soccer group, a Zumba group or a control group. Training was conducted outside working hours as two to three 1-h weekly sessions the first 3 months and once a week the last 6 months. Tests were conducted at baseline, after 3 and 9 months. The soccer group improved maximal neck extension strength both after 3 (1.2 kg; P flexibility. The present study indicates that workplace-initiated soccer and Zumba exercise may be beneficial for improvement of the neck and trunk strength, which may have preventive effects with regard to future perceived muscle pain in the respective body regions. Furthermore, the Zumba group revealed positive effects on lower limb lean mass and postural sway compared to the control group.

Field-aligned currents and convection patterns in the Southern Polar Cap during stable northward, southward, and azimuthal IMF

International Nuclear Information System (INIS)

Papitashvili, V.O.; Belov, B.A.; Gromova, L.I.

1989-01-01

Equivalent ionospheric current patterns are derived from ground-based geomagnetic observations for events on 11-12 November 1979 (B/sub z/ >> 0), 24 November 1981 (B/sub z/ > 0) (B/sub y/ >> 0), and 25-26 November 1979 (B/sub y/ 0 . Due to stable external conditions, it is possible to calculate the field-aligned current (FAC) density within cells formed by two adjacent stations by taking into account the uniform conductivity of the summer polar ionosphere. These results completely correspond to regressional analysis of interplanetary magnetic fields (IMF) and ground-based geomagnetic data, and also to satellite observations of the NBZ current system. During stable southward IMF a new result was obtained, a reversal of antisunward convection flow is identified, and an NBZ-like FAC system is restored in the central part of the southern polar cap. The authors conclude that there may be an additional NBZ-like FAC system poleward of -85 0 , which is independent of the IMF and is generated by the quasi-viscous interaction between solar-wind plasma and high-latitude lobes of the magnetospheric tail

Dynamical structure of center-of-pressure trajectories with and without functional taping in children with cerebral palsy level I and II of GMFCS.

Science.gov (United States)

Pavão, Silvia Leticia; Ledebt, Annick; Savelsbergh, Geert J P; Rocha, Nelci Adriana C F

2017-08-01

Postural control during quiet standing was examined in typical children (TD) and children with cerebral palsy (CP) level I and II of GMFCS. The immediate effect on postural control of functional taping on the thighs was analyzed. We evaluated 43 TD, 17 CP children level I, and 10 CP children level II. Participants were evaluated in two conditions (with and without taping). The trajectories of the center of pressure (COP) were analyzed by means of conventional posturography (sway amplitude, sway-path-length) and dynamic posturography (degree of twisting-and-turning, sway regularity). Both CP groups showed larger sway amplitude than the TD while only the CP level II showed more regular COP trajectories with less twisting-and-turning. Functional taping didn't affect sway amplitude or sway-path-length. TD children exhibited more twisting-and-turning with functional taping, whereas no effects on postural sway dynamics were observed in CP children. Functional taping doesn't result in immediate changes in quiet stance in CP children, whereas in TD it resulted in faster sway corrections. Children level II invest more attention in postural control than level I, and TD. While quiet standing was more automatized in children level I than in level II, both CP groups showed a less stable balance than TD. Copyright © 2017 Elsevier B.V. All rights reserved.

Diagnostic possibilities of radionuclide investigation in patterns with stable and unstable angina pectoris

International Nuclear Information System (INIS)

Ponomareva, A.G.; Zudbinov, Yu.I.; Sokolov, O.K.; Kudinov, V.I.

1986-01-01

Myocardial radiocardiography and scintigraphy with 99m Tc-pyrophosphate was performed in 58 patients with stable angina and 60 patients with unstable angina. In patients with stable angina, positive scintigrams were mostly recorded after anginal attacks. Their central hemodynamic parameters deteriorated progressively as angina increased in severity. Patients with unstable angina typically showed myocardial accumulation of the label that was unrelated to anginal attacks and recordable by direct-projection scintigraphy. The assessment of myocardial radiocardiographic and scintigraphic data allows one to differentiate between stable and unstable angina

Patterns in Stable Isotope Values of Nitrogen and Carbon in ...

Science.gov (United States)

Stable isotope measurements of nitrogen and carbon (15N, 13ddC) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is critical to interpreting values in these ecosystems. While base-level isotope data are generally readily available for estuaries, nearshore coastal waters, and the open ocean, the continental shelf is less studied. To address this, and as a first step toward developing a surrogate for base-level isotopic signature in this region, we collected surface and deep water samples from the United States’ eastern continental shelf in the Western Atlantic Ocean, from the Gulf of Maine to Cape Hatteras, periodically between 2000 and 2013. During the study, particulate matter 15dN values ranged from 0.8 to 17.4‰, and 13dC values from −26.4 to −15.6‰over the region. We used spatial autocorrelation analysis and random forest modeling to examine the spatial trends and potential environmental drivers of the stable isotope values. We observed general trends toward lower values for both nitrogen and carbon isotopes at the seaward edge of the shelf. Conversely, higher 15dN and 13dC values were observed on the landward edge of the shelf, in particular in the southern portion of the sampling area. Across all sites, the magnitude of the difference between the 15dN of subsurface and surface particulate m

Leg and trunk muscle coordination and postural sway during increasingly difficult standing balance tasks in young and older adults.

Science.gov (United States)

Donath, Lars; Kurz, Eduard; Roth, Ralf; Zahner, Lukas; Faude, Oliver

2016-09-01

Ageing impairs body balance and increases older adults' fall risk. Balance training can improve intrinsic fall risk factors. However, age comparisons of muscle activity responses during balance tasks are lacking. This study investigated relative muscle activity, muscle coordination and postural sway during various recommended static balance training tasks. Muscle activity (%MVC), amplitude ratios (AR) and co-activity (CAI) were determined during standing tasks for 30s (1: double limb stance on a foam surface, eyes open; 2: double limb stance on firm ground, eyes closed; 3: double limb stance, feet in step position on a foam surface, eyes open; 4: double limb stance, feet in step position on firm ground, eyes closed; 5: single limb stance on firm ground, eyes open) in 20 healthy young adults (24±2 y) and 20 older adults (73±6 y). Surface electromyography (SEMG) was applied (SENIAM guidelines) to ankle (tibialis anterior, soleus, medial gastrocnemius, peroneus longus) and thigh (vastus lateralis, vastus medialis, biceps femoris, semitendinosus) muscles (non-dominant leg). Electrodes over trunk (multifidus and internal oblique) muscles were applied bilaterally. Two- to six-fold higher levels of relative muscle activity were found in older adults for ankle (0.0002adults for the trunk (0.001older adults for the ankle (0.009Older adults had higher electrophysiological costs for all stance conditions. Muscle coordination showed inverse activity patterns at the ankle and trunk. Optimal balance and strength training programs should take into account age-specific alterations in muscle activity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Dietary patterns derived using exploratory and confirmatory factor analysis are stable and generalizable across race, region, and gender subgroups in the REGARDS study

Directory of Open Access Journals (Sweden)

Suzanne E Judd

2015-01-01

Full Text Available Background: Examining diet as a whole using dietary patterns as exposures is a complementary method to using single food or nutrients in studies of diet and disease, but the generalizability of patterns across race, region, and gender in the United States has not been established. Objective: To employ rigorous statistical analysis to empirically derive dietary patterns in a large bi-racial, geographically diverse population and examine whether results are stable across population subgroups.Design: The present analysis utilized data from 21,636 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS study who completed the Block98 food frequency questionnaire. We employed exploratory factor analysis and confirmatory factor analyses on 56 different food groups iteratively and examined differences by race, region, sex to determine the optimal factor solution in our sample. Results: Five dietary patterns emerged: the Convenience pattern was characterized by mixed dishes; the Plant-based pattern by fruits, vegetables, and fish; the Sweets/Fats pattern by sweet snacks, desserts, and fats and oils; the Southern pattern by fried foods, organ meat, and sweetened beverages; and the Alcohol/Salads pattern by beer, wine, liquor, and salads. Differences were most pronounced in the Southern pattern with black participants, those residing in the Southeast, and participants not completing high school having the highest scores. Conclusions: Five meaningful dietary patterns emerged in the REGARDS study and showed strong congruence across race, sex and region. Future research will examine associations between these patterns and health outcomes to better understand racial disparities in disease and inform prevention efforts.

Stable isotope (2H, 17O, 18O) and hydro chemical patterns of precipitation collected in weekly resolution at Hannover, Germany

Science.gov (United States)

Koeniger, Paul; Himmelsbach, Thomas

2016-04-01

Long-term observations of stable isotopes (δ18O and δ2H) in precipitation were initiated in May 2008 at the Federal Institute of Geosciences and Natural Resources (BGR) in Hannover, Germany. In 2014 all precipitation samples were re-analyzed because a purchase of a new laser spectrometer (Picarro L2140-i) now allowed measurements of δ17O and a calculation of the 17O-excess parameter. Starting in October 2015 a routine analysis of hydro chemical parameters was added whenever enough sample aliquot was available (major ions, trace elements). A discussion of the stable isotope data of the seven year series of weekly precipitation samples (n = 370) will be presented. Beneath general patterns (seasonality and trends) we also focus on importance of amount weighing procedures, corrections for minor rain amounts, aspects of sample storage and re-analyzes, as well as impacts through changes in analytical equipment (IRMS, CRD spectroscopy) which is visible from the data. For stable isotopes a Thermo Fisher delta plus IRMS (Gasbench and H-Device) was used until 2011 and from 2012 on a Picarro L2120-i water vapor analyzer with long-term accuracies for quality check samples better than 0.2‰ and 0.8‰ for δ18O and δ2H, respectively.

Dietary Patterns Derived Using Exploratory and Confirmatory Factor Analysis are Stable and Generalizable Across Race, Region, and Gender Subgroups in the REGARDS Study

Science.gov (United States)

Judd, Suzanne E.; Letter, Abraham J.; Shikany, James M.; Roth, David L.; Newby, P. K.

2015-01-01

Background: Examining diet as a whole using dietary patterns as exposures is a complementary method to using single food or nutrients in studies of diet and disease, but the generalizability of intake patterns across race, region, and gender in the United States has not been established. Objective: To employ rigorous statistical analysis to empirically derive dietary patterns in a large bi-racial, geographically diverse population and examine whether results are stable across population subgroups. Design: The present analysis utilized data from 21,636 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who completed the Block 98 food frequency questionnaire. We employed exploratory factor analysis and confirmatory factor analyses on 56 different food groups iteratively and examined differences by race, region, and sex to determine the optimal factor solution in our sample. Results: Five dietary patterns emerged: the “Convenience” pattern was characterized by mixed dishes; the “Plant-based” pattern by fruits, vegetables, and fish; the “Sweets/Fats” pattern by sweet snacks, desserts, and fats and oils; the “Southern” pattern by fried foods, organ meat, and sweetened beverages; and the “Alcohol/Salads” pattern by beer, wine, liquor, and salads. Differences were most pronounced in the Southern pattern with black participants, those residing in the Southeast, and participants not completing high school having the highest scores. Conclusion: Five meaningful dietary patterns emerged in the REGARDS study and showed strong congruence across race, sex, and region. Future research will examine associations between these patterns and health outcomes to better understand racial disparities in disease and inform prevention efforts. PMID:25988129

Altered postural control strategies in quiet standing more than 20 years after rupture of the anterior cruciate ligament.

Science.gov (United States)

Stensdotter, Ann-Katrin; Tengman, Eva; Häger, Charlotte

2016-05-01

To explore long-term consequences of anterior cruciate ligament (ACL) rupture on postural sway and control strategies during bilateral quiet standing, in subjects treated with or without reconstructive surgery compared to uninjured controls. 70 individuals who had unilateral ACL rupture 23±2.4 years ago (33 received ACL reconstructive surgery, ACLR, and 37 had physiotherapy only, ACLPT) and 33 uninjured matched controls (CTRL) (mean age 46±5.3) stood quietly with eyes closed for 3min on a firm and on a compliant surface, respectively. Center of pressure (CoP) was registered with a force plate and postural sway was calculated from center of mass (CoM) derived from 3D kinematics. Sway density (SD) analyses of CoP assessed distance and duration of stable phases. The torque controlling postural sway was estimated from CoP-CoM. Comparisons across conditions to CTRL revealed larger CoP-CoM-area in ACLR (p=0.017, CI: 10.95, 143.10), but not in ACLPT. Mean distance between SD-peaks was greater for ACLR (ppostural control efforts than CTRL but without significant differences in postural sway. Control efforts were thus not directly associated with sway and further research should be focused on variance in postural control strategies. Copyright © 2016. Published by Elsevier B.V.

Application of stable isotopes in ecological research : it's all elemental

International Nuclear Information System (INIS)

Rogers, K.M.

2005-01-01

Stable isotopes have been used traditionally in the physical sciences, primarily in geochemistry, sedimentology, and oceanography. Increasingly, however, stable isotopes are also being used in the biological sciences. Application of stable isotopes in ecological studies can provide new and innovative ways of examining a host of topics of fundamental importance to biologists. These topics include, among others, feeding ecology and food webs, nutrient flow and assimilation, habitat use, migration patterns, and distribution and discrimination of species subpopulations. Furthermore, ecological research with isotopes can be applied at many levels (i.e. tissue and organ, whole animal, population, community, and ecosystem). (author). 38 refs., 2 figs

First stable isotope analysis of Asiatic wild ass tail hair from the Mongolian Gobi.

Science.gov (United States)

Horacek, Micha; Sturm, Martina Burnik; Kaczensky, Petra

Stable isotope analysis has become a powerful tool to study feeding ecology, water use or movement pattern in contemporary, historic and ancient species. Certain hair and teeth grow continuously, and when sampled longitudinally can provide temporally explicit information on dietary regime and movement pattern. In an initial trial, we analysed a tail sample of an Asiatic wild ass ( Equus hemionus ) from the Mongolian Gobi. We found seasonal variations in H, C and N isotope patterns, likely being the result of temporal variations in available feeds, water supply and possibly physiological status. Thus stable isotope analysis shows promise to study the comparative ecology of the three autochthonous equid species in the Mongolian Gobi.

Different ankle muscle coordination patterns and co-activation during quiet stance between young adults and seniors do not change after a bout of high intensity training.

Science.gov (United States)

Donath, Lars; Kurz, Eduard; Roth, Ralf; Zahner, Lukas; Faude, Oliver

2015-03-04

Available evidence suggests that young adults and seniors use different strategies to adjust for increasing body sway during quiet standing. Altered antagonist muscle co-activation and different ankle muscle coordination patterns may account for this finding. Consequently, we aimed at addressing whether aging leads to changes in neuromuscular coordination patterns as well as co-activation during quiet stance. We additionally investigated whether a bout of high intensity interval training additionally alters these patterns. Twenty healthy seniors (age: 70 ± 4 y) and twenty young adults (age: 27 ± 3 y) were enrolled in the present study. In between the testing procedures, four consecutive high-intensity intervals of 4 min duration at a target exercise intensity of 90 to 95% HRmax were completed on a treadmill. The total center of pressure (COP) path length displacement served as standing balance performance outcome. In order to assess ankle muscle coordination patterns, amplitude ratios (AR) were calculated for each muscle (e.g. tibialis anterior (TA) [%] = (TA × 100)/(gastrocnemius medialis (GM) + soleus (SOL) + peroneus longus (PL) + TA). The co-activation was calculated for the SOL and TA muscles computing the co-activation index (CAI = 2 × TA/TA + SOL). Seniors showed an inverted ankle muscle coordination pattern during single limb stance with eyes open (SLEO), compared to young adults (rest: GM, S: 15 ± 8% vs Y: 24 ± 9%; p = 0.03; SOL, S: 27 ± 14% vs Y: 37 ± 18%; p = 0.009; TA, S: 31 ± 13% vs Y: 13 ± 7%; p = 0.003). These patterns did not change after a high-intensity training session. A moderate correlation between amplitude ratios of the TA-contribution and postural sway was observed for seniors during SLEO (r = 0.61). Ankle co-activation was twofold elevated in seniors compared to young adults during SLEO (p Seniors with decreased postural control showed higher TA

Estimation of Sway Velocity-Dependent Hydrodynamic Derivatives in Surface Ship Manoeuvring Using Ranse Based CFD

Directory of Open Access Journals (Sweden)

Sheeja Janardhanan

2010-09-01

Full Text Available The hydrodynamic derivatives appearing in the manoeuvring equations of motion are the primary parameters in the prediction of the trajectory of a vessel. Determination of these derivatives poses major challenge in ship manoeuvring related problems. This paper deals with one such problem in which an attempt has been made to numerically simulate the conventional straight line test in a towing tank using computational fluid dynamics (CFD. Free-surface effects have been neglected here. The domain size has been fixed as per ITTC guide lines. The grid size has been fixed after a thorough grid independency analysis and an optimum grid size has been chosen in order to ensure the insensitivity of the flow parameters to grid size and also to have reduced computational effort. The model has been oriented to wider range of drift angles to capture the non-linear effects and subsequently the forces and moments acting on the model in each angle have been estimated. The sway velocity dependent derivatives have been obtained through plots and curve-fits. The effect of finite water depth on the derivatives has also been looked into. The results have been compared with the available experimental and empirical values and the method was found to be promising.

Stable multiple-layer stationary solutions of a semilinear parabolic equation in two-dimensional domains

Directory of Open Access Journals (Sweden)

Arnaldo Simal do Nascimento

1997-12-01

Full Text Available We use $Gamma$--convergence to prove existence of stable multiple--layer stationary solutions (stable patterns to the reaction--diffusion equation. $$ eqalign{ {partial v_varepsilon over partial t} =& varepsilon^2, hbox{div}, (k_1(xabla v_varepsilon + k_2(x(v_varepsilon -alpha(Beta-v_varepsilon (v_varepsilon -gamma_varepsilon(x,,hbox{ in }Omegaimes{Bbb R}^+ cr &v_varepsilon(x,0 = v_0 quad {partial v_varepsilon over partial widehat{n}} = 0,, quadhbox{ for } xin partialOmega,, t >0,.} $$ Given nested simple closed curves in ${Bbb R}^2$, we give sufficient conditions on their curvature so that the reaction--diffusion problem possesses a family of stable patterns. In particular, we extend to two-dimensional domains and to a spatially inhomogeneous source term, a previous result by Yanagida and Miyata.

Auditory white noise reduces age-related fluctuations in balance.

Science.gov (United States)

Ross, J M; Will, O J; McGann, Z; Balasubramaniam, R

2016-09-06

Fall prevention technologies have the potential to improve the lives of older adults. Because of the multisensory nature of human balance control, sensory therapies, including some involving tactile and auditory noise, are being explored that might reduce increased balance variability due to typical age-related sensory declines. Auditory white noise has previously been shown to reduce postural sway variability in healthy young adults. In the present experiment, we examined this treatment in young adults and typically aging older adults. We measured postural sway of healthy young adults and adults over the age of 65 years during silence and auditory white noise, with and without vision. Our results show reduced postural sway variability in young and older adults with auditory noise, even in the absence of vision. We show that vision and noise can reduce sway variability for both feedback-based and exploratory balance processes. In addition, we show changes with auditory noise in nonlinear patterns of sway in older adults that reflect what is more typical of young adults, and these changes did not interfere with the typical random walk behavior of sway. Our results suggest that auditory noise might be valuable for therapeutic and rehabilitative purposes in older adults with typical age-related balance variability. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

A crawling robot driven by multi-stable origami

Science.gov (United States)

Pagano, Alexander; Yan, Tongxi; Chien, Brian; Wissa, A.; Tawfick, S.

2017-09-01

Using origami folding to construct and actuate mechanisms and machines offers attractive opportunities from small, scalable, and cheap robots to deployable adaptive structures. This paper presents the design of a bio-inspired origami crawling robot constructed by folding sheets of paper. The origami building block structure is based on the Kresling crease pattern (CP), a chiral tower with a polygonal base, which expands and contracts through coupled longitudinal and rotational motion similar to a screw. We design the origami to have multi-stable structural equilibria which can be tuned by changing the folding CP. Kinematic analysis of these structures based on rigid-plates and hinges at fold lines precludes the shape transformation associated with the bistability of the physical models. To capture the kinematics of the bi-stable origami, the panels’ deformation behavior is modeled utilizing principles of virtual folds. Virtual folds approximate material bending by hinged, rigid panels, which facilitates the development of a kinematic solution via rigid-plate rotation analysis. As such, the kinetics and stability of folded structures are investigated by assigning suitable torsional spring constants to the fold lines. The results presented demonstrate the effect of fold-pattern geometries on the snapping behavior of the bi-stable origami structure based on the Kresling pattern. The crawling robot is presented as a case study for the use of this origami structure to mimic crawling locomotion. The robot is comprised of two origami towers nested inside a paper bellow, and connected by 3D printed end plates. DC motors are used to actuate the expansion and contraction of the internal origami structures to achieve forward locomotion and steering. Beyond locomotion, this simple design can find applications in manipulators, booms, and active structures.

Psychological and Demographic Correlates of Career Patterns

Science.gov (United States)

Reitzle, Matthias; Korner, Astrid; Vondracek, Fred W.

2009-01-01

Recent years have witnessed a growing diversity of career patterns, resulting from the relative decline of stable employment. In the present study of 1368 employed and self-employed German adults career pattern diversity was assessed using nine pictograms. The goal was to identify psychological and demographic correlates of these patterns and to…

Seasonal Cyclicity in Trace Elements and Stable Isotopes of Modern Horse Enamel.

Science.gov (United States)

de Winter, Niels J; Snoeck, Christophe; Claeys, Philippe

2016-01-01

The study of stable isotopes in fossil bioapatite has yielded useful results and has shown that bioapatites are able to faithfully record paleo-environmental and paleo-climatic parameters from archeological to geological timescales. In an effort to establish new proxies for the study of bioapatites, intra-tooth records of enamel carbonate stable isotope ratios from a modern horse are compared with trace element profiles measured using laboratory micro X-Ray Fluorescence scanning. Using known patterns of tooth eruption and the relationship between stable oxygen isotopes and local temperature seasonality, an age model is constructed that links records from six cheek upper right teeth from the second premolar to the third molar. When plotted on this age model, the trace element ratios from horse tooth enamel show a seasonal pattern with a small shift in phase compared to stable oxygen isotope ratios. While stable oxygen and carbon isotopes in tooth enamel are forced respectively by the state of the hydrological cycle and the animal's diet, we argue that the seasonal signal in trace elements reflects seasonal changes in dust intake and diet of the animal. The latter explanation is in agreement with seasonal changes observed in carbon isotopes of the same teeth. This external forcing of trace element composition in mammal tooth enamel implies that trace element ratios may be used as proxies for seasonal changes in paleo-environment and paleo-diet.

Letter to the Editor: On "Advantages and disadvantages of stiffness instructions when studying postural control" by C.T. Bonnet: You just can't win: Advantages and disadvantages of the postural stability requirement.

Science.gov (United States)

Lajoie, Y; Richer, N; Jehu, D A; Polskaia, N; Saunders, D

2016-05-01

In the examination of postural control, instructions to stand as still as possible are common and promote a relatively unnatural sway pattern. The validity of the stability requirement is discussed in the present commentary in response to the discussion initiated by Cedrick T. Bonnet. The advantages of using the stability requirement include: evaluating unbiased postural control, reducing variability in postural sway, manipulating focus of attention, examining the ability to maintain an upright stance, and ecological validity of testing. The disadvantages include: constraining natural postural sway, increasing the complexity of the control condition, promoting an internal focus of attention, and reducing the ability to detect exploratory behaviour. After evaluating the aforementioned advantages and disadvantages, the present commentary suggests that researchers should strive to provide specific instructions to maintain feet, arm and eye position without specifically requiring participants to reduce their postural sway. Copyright © 2015 Elsevier B.V. All rights reserved.

Stable convergence and stable limit theorems

CERN Document Server

Häusler, Erich

2015-01-01

The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

Effect of cognitive challenge on the postural control of patients with ACL reconstruction under visual and surface perturbations.

Science.gov (United States)

Lion, Alexis; Gette, Paul; Meyer, Christophe; Seil, Romain; Theisen, Daniel

2018-02-01

Our study aimed to evaluate the effect of cognitive challenge on double-leg postural control under visual and surface perturbations of patients with anterior cruciate ligament reconstruction (ACLR) cleared to return to sport. Double-leg stance postural control of 19 rehabilitated patients with ACLR (age: 24.8 ± 6.7 years, time since surgery: 9.2 ± 1.6 months) and 21 controls (age: 24.9 ± 3.7 years) was evaluated in eight randomized situations combining two cognitive (with and without silent backward counting in steps of seven), two visual (eyes open, eyes closed) and two surface (stable support, foam support) conditions. Sway area and sway path of the centre of foot pressure were measured during three 20-s recordings for each situation. Higher values indicated poorer postural control. Generally, postural control of patients with ACLR and controls was similar for sway area and sway path (p > 0.05). The lack of visual anchorage and the disturbance of the plantar input by the foam support increased sway area and sway path (p postural control during double-leg stance tests. The use of a dual task paradigm under increased task complexity modified postural control, but in a similar way in patients with ACLR than in healthy controls. Double-leg stance tests, even under challenging conditions, are not sensitive enough to reveal postural control differences between rehabilitated patients with ACLR and controls. Copyright © 2017 Elsevier B.V. All rights reserved.

Associations of anthropometry since birth with sagittal posture at age 7 in a prospective birth cohort: the Generation XXI Study.

Science.gov (United States)

Araújo, Fábio A; Lucas, Raquel; Simpkin, Andrew J; Heron, Jon; Alegrete, Nuno; Tilling, Kate; Howe, Laura D; Barros, Henrique

2017-07-26

Adult sagittal posture is established during childhood and adolescence. A flattened or hypercurved spine is associated with poorer musculoskeletal health in adulthood. Although anthropometry from birth onwards is expected to be a key influence on sagittal posture design, this has never been assessed during childhood. Our aim was to estimate the association between body size throughout childhood with sagittal postural patterns at age 7. Prospective cohort study. A subsample of 1029 girls and 1101 boys taking part in the 7-year-old follow-up of the birth cohort Generation XXI (Porto, Portugal) was included. We assessed the associations between anthropometric measurements (weight, height and body mass index) at birth, 4 and 7 years of age and postural patterns at age 7. Postural patterns were defined using latent profile analysis, a probabilistic model-based technique which allows for simultaneously including anthropometrics as predictors of latent profiles by means of logistic regression. Postural patterns identified were sway, flat and "neutral to hyperlordotic"in girls, and "sway to neutral", flat and hyperlordotic in boys; with flat and hyperlordotic postures representing a straightened and a rounded spine, respectively. In both girls and boys, higher weight was associated with lower odds of a flat pattern compared with a sway/"sway to neutral"pattern, with stronger associations at older ages: for example, ORs were 0.68 (95% CI 0.53 to 0.88) per SD increase in birth weight and 0.36 (95% CI 0.19 to 0.68) per SD increase in weight at age 7 in girls, with similar findings in boys. Boys with higher ponderal index at birth were more frequently assigned to the hyperlordotic pattern (OR=1.44 per SD; p=0.043). Our findings support a prospective sculpting role of body size and therefore of load on musculoskeletal spinopelvic structures, with stronger associations as children get older. © Article author(s) (or their employer(s) unless otherwise stated in the text of the

Chimera patterns in the Kuramoto–Battogtokh model

International Nuclear Information System (INIS)

Smirnov, Lev; Osipov, Grigory; Pikovsky, Arkady

2017-01-01

Kuramoto and Battogtokh (2002 Nonlinear Phenom. Complex Syst . 5 380) discovered chimera states represented by stable coexisting synchrony and asynchrony domains in a lattice of coupled oscillators. After a reformulation in terms of a local order parameter, the problem can be reduced to partial differential equations. We find uniformly rotating, spatially periodic chimera patterns as solutions of a reversible ordinary differential equation, and demonstrate a plethora of such states. In the limit of neutral coupling they reduce to analytical solutions in the form of one- and two-point chimera patterns as well as localized chimera solitons. Patterns at weakly attracting coupling are characterized by virtue of a perturbative approach. Stability analysis reveals that only the simplest chimeras with one synchronous region are stable. (letter)

Chimera patterns in the Kuramoto-Battogtokh model

Science.gov (United States)

Smirnov, Lev; Osipov, Grigory; Pikovsky, Arkady

2017-02-01

Kuramoto and Battogtokh (2002 Nonlinear Phenom. Complex Syst. 5 380) discovered chimera states represented by stable coexisting synchrony and asynchrony domains in a lattice of coupled oscillators. After a reformulation in terms of a local order parameter, the problem can be reduced to partial differential equations. We find uniformly rotating, spatially periodic chimera patterns as solutions of a reversible ordinary differential equation, and demonstrate a plethora of such states. In the limit of neutral coupling they reduce to analytical solutions in the form of one- and two-point chimera patterns as well as localized chimera solitons. Patterns at weakly attracting coupling are characterized by virtue of a perturbative approach. Stability analysis reveals that only the simplest chimeras with one synchronous region are stable.

Model of the transverse modes of stable and unstable porro–prism resonators using symmetry considerations

CSIR Research Space (South Africa)

Burger, L

2007-01-01

Full Text Available of this type of resonator. Further use of the model reveals the formation of more complex beam patterns, and the nature of these patterns is investigated. Also, the output of stable and unstable resonator modes is presented....

Difference in postural control between patients with functional and mechanical ankle instability.

Science.gov (United States)

Chen, Henry; Li, Hong-Yun; Zhang, Jian; Hua, Ying-Hui; Chen, Shi-Yi

2014-10-01

Lateral ankle sprain is one of the most common injuries. Since the structural and pathological differences in mechanical ankle instability (MAI) and functional ankle instability (FAI) may not be the same, it may be better to treat these as separate groups. The purpose of this study was to compare the difference in postural sway between MAI and FAI in patients with chronic ankle instability (CAI). Twenty-six patients with CAI and 14 healthy control participants were included in the study. The CAI patients were subdivided into MAI (15 patients) and FAI (11 patients) groups. Patients who were diagnosed with lateral ankle ligaments rupture by magnetic resonance imaging and ultrasonography were assigned to the MAI group. All participants performed single-limb postural sway tests 3 times on each leg with eyes closed and open. The average distances from the mean center of pressure position in the mediolateral and anteroposterior directions were recorded and compared among the 3 groups. The unstable ankles in the MAI group showed significantly greater postural sway in the anterior, posterior, and medial directions compared with those in the control group with eyes closed. With eyes open, significantly greater postural sway was found in the anterior direction. In the FAI group, no difference was found in postural sway compared with those in the control group. The MAI group showed significantly greater postural sway in the anterior direction compared with the FAI group with eyes closed and open. No significant difference in postural sway was found between the unstable and stable ankles in the MAI or FAI groups, with or without vision. Patients with MAI have deficits in postural control, especially in anterior-posterior directions. However, no difference was found in postural sway in patients with FAI compared with healthy people. As MAI patients suffer from deficits in postural control, balance training should be applied in those patients. In addition, special training

Seasonal Cyclicity in Trace Elements and Stable Isotopes of Modern Horse Enamel.

Directory of Open Access Journals (Sweden)

Niels J de Winter

Full Text Available The study of stable isotopes in fossil bioapatite has yielded useful results and has shown that bioapatites are able to faithfully record paleo-environmental and paleo-climatic parameters from archeological to geological timescales. In an effort to establish new proxies for the study of bioapatites, intra-tooth records of enamel carbonate stable isotope ratios from a modern horse are compared with trace element profiles measured using laboratory micro X-Ray Fluorescence scanning. Using known patterns of tooth eruption and the relationship between stable oxygen isotopes and local temperature seasonality, an age model is constructed that links records from six cheek upper right teeth from the second premolar to the third molar. When plotted on this age model, the trace element ratios from horse tooth enamel show a seasonal pattern with a small shift in phase compared to stable oxygen isotope ratios. While stable oxygen and carbon isotopes in tooth enamel are forced respectively by the state of the hydrological cycle and the animal's diet, we argue that the seasonal signal in trace elements reflects seasonal changes in dust intake and diet of the animal. The latter explanation is in agreement with seasonal changes observed in carbon isotopes of the same teeth. This external forcing of trace element composition in mammal tooth enamel implies that trace element ratios may be used as proxies for seasonal changes in paleo-environment and paleo-diet.

Distribution of radiocesium and stable elements within a pine tree

International Nuclear Information System (INIS)

Yoshida, S.; Watanabe, M.; Suzuki, A.

2011-01-01

Distributions of 137 Cs and stable elements in different parts of a pine tree collected in Chernobyl-contaminated area in Belarus were determined. Samples include annual tree rings of wood, branches and needles with different ages. The concentrations of 137 Cs and stable Cs in annual tree rings were the highest in cambium and decreased sharply towards inside. The youngest needles and branches contained higher 137 Cs and stable Cs than older ones. The concentration of 137 Cs being highest in growing parts suggests the highest radiation dose to the radiation-sensitive parts of tree. Distribution patterns of stable elements in pine tree differ among the elements. Distributions similar to those of Cs were observed for K and Rb, suggesting that alkaline metals tend to be translocated to young growing parts of pine tree. A similar distribution was also observed for phosphorus. Distributions of alkaline earth metals and several heavy metals were different from those of alkaline metals. (authors)

Study of horizontal-vertical interactive Sway Rocking (SR) model for basemat uplift. Part 2: non-linear response analysis and validation

International Nuclear Information System (INIS)

Momma, T.; Shirahama, K.; Suzuki, K.; Ogihara, M.

1995-01-01

Non-linear earthquake response analyses of a BWR MARK-II type nuclear reactor building are conducted by using a Sway Rocking model (SR model) proposed in Part 1 considering the interaction between horizontal and vertical motion. The results are compared with those of accurate mathematical model using the Green Function method. Horizontal response of the SR model agrees very well with that of the Green Function model. The floor response spectra of induced vertical motions by both methods are also corresponding well in periodic characteristics as well as peak-levels. From these results, it is confirmed that the horizontal-vertical interactive SR model is applicable to non-linear response analyses considering basemat uplift. Based on the comparison of the induced vertical motions due to basemat uplift by both methods, an application limit of the horizontal-vertical interactive SR model is set up at the ground contact ratio of about 50%. (author). 4 refs., 8 figs., 1 tab

Haptic cues for orientation and postural control in sighted and blind individuals

Science.gov (United States)

Jeka, J. J.; Easton, R. D.; Bentzen, B. L.; Lackner, J. R.

1996-01-01

Haptic cues from fingertip contact with a stable surface attenuate body sway in subjects even when the contact forces are too small to provide physical support of the body. We investigated how haptic cues derived from contact of a cane with a stationary surface at low force levels aids postural control in sighted and congenitally blind individuals. Five sighted (eyes closed) and five congenitally blind subjects maintained a tandem Romberg stance in five conditions: (1) no cane; (2,3) touch contact (postural sway in all subjects, compared to the no-cane condition. A slanted cane was far more effective in reducing postural sway than was a perpendicular cane. Cane use also decreased head displacement of sighted subjects far more than that of blind subjects. These results suggest that head movement control is linked to postural control through gaze stabilization reflexes in sighted subjects; such reflexes are absent in congenitally blind individuals and may account for their higher levels of head displacement.

Engineering stable topography in dense bio-mimetic 3D collagen scaffolds

Directory of Open Access Journals (Sweden)

T Alekseeva

2012-01-01

Full Text Available Topographic features are well known to influence cell behaviour and can provide a powerful tool for engineering complex, functional tissues. This study aimed to investigate the mechanisms of formation of a stable micro-topography on plastic compressed (PC collagen gels. The uni-directional fluid flow that accompanies PC of collagen gels creates a fluid leaving surface (FLS and a non-fluid leaving surface (non-FLS. Here we tested the hypothesis that the resulting anisotropy in collagen density and stiffness between FLS and non-FLS would influence the fidelity and stability of micro-grooves patterned on these surfaces. A pattern template of parallel-aligned glass fibres was introduced to the FLS or non-FLS either at the start of the compression or halfway through, when a dense FLS had already formed. Results showed that both early and late patterning of the FLS generated grooves that had depth (25 ±7 µm and 19 ±8 µm, respectively and width (55 ±11 µm and 50 ±12 µm, respectively which matched the glass fibre diameter (50 µm. In contrast, early and late patterning of the non-FLS gave much wider (151 ±50 µm and 89 ±14 µm, respectively and shallower (10 ±2.7 µm and 13 ±3.5 µm, respectively grooves than expected. The depth to width ratio of the grooves generated on the FLS remained unaltered under static culture conditions over 2 weeks, indicating that grooves were stable under long term active cell-mediated matrix remodelling. These results indicate that the FLS, characterised by a higher matrix collagen density and stiffness than the non-FLS, provides the most favourable mechanical surface for precise engineering of a stable micro-topography in 3D collagen hydrogel scaffolds.

A stable pattern of EEG spectral coherence distinguishes children with autism from neuro-typical controls - a large case control study

Directory of Open Access Journals (Sweden)

Duffy Frank H

2012-06-01

Full Text Available Abstract Background The autism rate has recently increased to 1 in 100 children. Genetic studies demonstrate poorly understood complexity. Environmental factors apparently also play a role. Magnetic resonance imaging (MRI studies demonstrate increased brain sizes and altered connectivity. Electroencephalogram (EEG coherence studies confirm connectivity changes. However, genetic-, MRI- and/or EEG-based diagnostic tests are not yet available. The varied study results likely reflect methodological and population differences, small samples and, for EEG, lack of attention to group-specific artifact. Methods Of the 1,304 subjects who participated in this study, with ages ranging from 1 to 18 years old and assessed with comparable EEG studies, 463 children were diagnosed with autism spectrum disorder (ASD; 571 children were neuro-typical controls (C. After artifact management, principal components analysis (PCA identified EEG spectral coherence factors with corresponding loading patterns. The 2- to 12-year-old subsample consisted of 430 ASD- and 554 C-group subjects (n = 984. Discriminant function analysis (DFA determined the spectral coherence factors' discrimination success for the two groups. Loading patterns on the DFA-selected coherence factors described ASD-specific coherence differences when compared to controls. Results Total sample PCA of coherence data identified 40 factors which explained 50.8% of the total population variance. For the 2- to 12-year-olds, the 40 factors showed highly significant group differences (P Conclusions Classification success suggests a stable coherence loading pattern that differentiates ASD- from C-group subjects. This might constitute an EEG coherence-based phenotype of childhood autism. The predominantly reduced short-distance coherences may indicate poor local network function. The increased long-distance coherences may represent compensatory processes or reduced neural pruning. The wide average spectral range

Longitudinal fasting blood glucose patterns and arterial stiffness risk in a population without diabetes.

Science.gov (United States)

Wu, Yuntao; Yu, Junxing; Jin, Cheng; Li, Yun; Su, Jinmei; Wei, Guoqing; Zheng, Xiaoming; Gao, Jingsheng; Gao, Wenyuan; Wu, Shouling

2017-01-01

To identify long-term fasting blood glucose trajectories and to assess the association between the trajectories and the risk of arterial stiffness in individuals without diabetes. We enrolled 16,454 non-diabetic participants from Kailuan cohort. Fasting blood glucose concentrations were measured in 2006, 2008, and 2010 survey. Brachial-ankle pulse wave velocities were measured during 2011 to 2016. Multivariate regression model was used to estimate the difference of brachial-ankle pulse wave velocity levels and logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (95%CIs) of arterial stiffness risk, according to the fasting blood glucose trajectories. We identified five distinct fasting blood glucose trajectories and each of the trajectories was labeled according to its range and change over 2006-2010 survey: elevated-stable pattern (5.0% of participants), elevated-decreasing pattern (6.6%), moderate-increasing pattern (10.9%), moderate-stable pattern (59.3%), and low-stable pattern (18.2%). After adjustment for potential confounders, individuals with elevated-stable pattern had a 42.6 cm/s (95%CI: 24.7 to 60.6 cm/s) higher brachial-ankle pulse wave velocity level and a 37% (OR 1.37, 95%CI: 1.14 to 1.66) higher arterial stiffness risk, and individuals with moderate-increasing pattern had a 19.6 cm/s (95%CI: 6.9 to 32.3 cm/s) higher brachial-ankle pulse wave velocity level and a 17% (OR 1.17, 95%CI: 1.03 to 1.33) higher arterial stiffness risk, related to individuals with moderate-stable pattern. We did not find significant associations of the elevated-decreasing or low-stable patterns with arterial stiffness. Consistently, the cumulative average, variability, and increased rate of fasting blood glucose during 2006-2010 survey were significantly associated with the arterial stiffness risk. Discrete fasting blood glucose trajectories were associated with the arterial stiffness risk in non-diabetic individuals.

Pattern formation, logistics, and maximum path probability

Science.gov (United States)

Kirkaldy, J. S.

1985-05-01

The concept of pattern formation, which to current researchers is a synonym for self-organization, carries the connotation of deductive logic together with the process of spontaneous inference. Defining a pattern as an equivalence relation on a set of thermodynamic objects, we establish that a large class of irreversible pattern-forming systems, evolving along idealized quasisteady paths, approaches the stable steady state as a mapping upon the formal deductive imperatives of a propositional function calculus. In the preamble the classical reversible thermodynamics of composite systems is analyzed as an externally manipulated system of space partitioning and classification based on ideal enclosures and diaphragms. The diaphragms have discrete classification capabilities which are designated in relation to conserved quantities by descriptors such as impervious, diathermal, and adiabatic. Differentiability in the continuum thermodynamic calculus is invoked as equivalent to analyticity and consistency in the underlying class or sentential calculus. The seat of inference, however, rests with the thermodynamicist. In the transition to an irreversible pattern-forming system the defined nature of the composite reservoirs remains, but a given diaphragm is replaced by a pattern-forming system which by its nature is a spontaneously evolving volume partitioner and classifier of invariants. The seat of volition or inference for the classification system is thus transferred from the experimenter or theoretician to the diaphragm, and with it the full deductive facility. The equivalence relations or partitions associated with the emerging patterns may thus be associated with theorems of the natural pattern-forming calculus. The entropy function, together with its derivatives, is the vehicle which relates the logistics of reservoirs and diaphragms to the analog logistics of the continuum. Maximum path probability or second-order differentiability of the entropy in isolation are

Stable isotopes in Lithuanian bioarcheological material

Science.gov (United States)

Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

2015-04-01

Schutkowski. "Diet and social status during the La Tène period in Bohemia: carbon and nitrogen stable isotope analysis of bone collagen from Kutná Hora-Karlov and Radovesice." Journal of Anthropological Archaeology 24.2 (2005): 135-147. Schutkowski, Holger, et al. "Diet, status and decomposition at Weingarten: trace element and isotope analyses on early mediaeval skeletal material." Journal of Archaeological Science 26.6 (1999): 675-685. Zernitskaya, Valentina, et al. "Vegetation pattern and sedimentation changes in the context of the Lateglacial climatic events: Case study of Staroje Lake (Eastern Belarus)." Quaternary International (2014).

Stable annual pattern of water use by Acacia tortilis in Sahelian Africa.

Science.gov (United States)

Do, Frederic C; Rocheteau, Alain; Diagne, Amadou L; Goudiaby, Venceslas; Granier, André; Lhomme, Jean-Paul

2008-01-01

Water use by mature trees of Acacia tortilis (Forsk.) Hayne ssp. raddiana (Savi) Brenan var. raddiana growing in the northern Sahel was continuously recorded over 4 years. Water use was estimated from xylem sap flow measured by transient heat dissipation. Concurrently, cambial growth, canopy phenology, leaf water potential, climatic conditions and soil water availability (SWA) were monitored. In addition to the variation attributable to interannual variation in rainfall, SWA was increased by irrigation during one wet season. The wet season lasted from July to September, and annual rainfall ranged between 146 and 367 mm. The annual amount and pattern of tree water use were stable from year-to-year despite interannual and seasonal variations in SWA in the upper soil layers. Acacia tortilis transpired readily throughout the year, except for one month during the dry season when defoliation was at a maximum. Maximum water use of about 23 l (dm sapwood area)(-2) day(-1) was recorded at the end of the wet season. While trees retained foliage in the dry season, the decline in water use was modest at around 30%. Variation in predawn leaf water potential indicated that the trees were subject to soil water constraint. The rapid depletion of water in the uppermost soil layers after the wet season implies that there was extensive use of water from deep soil layers. The deep soil profile revealed (1) the existence of living roots at 25 m and (2) that the availability of soil water was low (-1.6 MPa) down to the water table at a depth of 31 m. However, transpiration was recorded at a predawn leaf water potential of -2.0 MPa, indicating that the trees used water from both intermediary soil layers and the water table. During the full canopy stage, mean values of whole-tree hydraulic conductance were similar in the wet and dry seasons. We propose that the stability of water use at the seasonal and annual scales resulted from a combination of features, including an extensive rooting

New stable phase in binary Fe-Nd

International Nuclear Information System (INIS)

Schneider, G.; Landgraf, F.J.G.; Villas-Boas, V.; Bezerra, G.H.; Missell, F.P.; Ray, A.E.

1992-01-01

An investigation of binary Fe-Nd alloys revealed the existence of an oxygen-free, stable Fe-rich phase A 2 , formed peritecticly in the range 750-800 deg C. EPMA shows this phase to contain 22.8 atomic percent Nd. This ferromagnetic phase has T c = 230 de C, but is magnetically soft. The X-ray diffraction pattern can be indexed using a hexagonal cell with a = 2.021 nm. and c = 1.235 nm. (author)

Dynamic Determinants of the Uncontrolled Manifold during Human Quiet Stance.

Science.gov (United States)

Suzuki, Yasuyuki; Morimoto, Hiroki; Kiyono, Ken; Morasso, Pietro G; Nomura, Taishin

2016-01-01

Human postural sway during stance arises from coordinated multi-joint movements. Thus, a sway trajectory represented by a time-varying postural vector in the multiple-joint-angle-space tends to be constrained to a low-dimensional subspace. It has been proposed that the subspace corresponds to a manifold defined by a kinematic constraint, such that the position of the center of mass (CoM) of the whole body is constant in time, referred to as the kinematic uncontrolled manifold ( kinematic-UCM ). A control strategy related to this hypothesis ( CoM-control-strategy ) claims that the central nervous system (CNS) aims to keep the posture close to the kinematic-UCM using a continuous feedback controller, leading to sway patterns that mostly occur within the kinematic-UCM, where no corrective control is exerted. An alternative strategy proposed by the authors ( intermittent control-strategy ) claims that the CNS stabilizes posture by intermittently suspending the active feedback controller, in such a way to allow the CNS to exploit a stable manifold of the saddle-type upright equilibrium in the state-space of the system, referred to as the dynamic-UCM , when the state point is on or near the manifold. Although the mathematical definitions of the kinematic- and dynamic-UCM are completely different, both UCMs play similar roles in the stabilization of multi-joint upright posture. The purpose of this study was to compare the dynamic performance of the two control strategies. In particular, we considered a double-inverted-pendulum-model of postural control, and analyzed the two UCMs defined above. We first showed that the geometric configurations of the two UCMs are almost identical. We then investigated whether the UCM-component of experimental sway could be considered as passive dynamics with no active control, and showed that such UCM-component mainly consists of high frequency oscillations above 1 Hz, corresponding to anti-phase coordination between the ankle and hip. We

Dynamic determinants of the uncontrolled manifold during human quiet stance

Directory of Open Access Journals (Sweden)

Yasuyuki Suzuki

2016-12-01

Full Text Available Human postural sway during stance arises from coordinated multi-joint movements. Thus, a sway trajectory represented by a time-varying postural vector in the multiple-joint-angle-space tends to be constrained to a low-dimensional subspace. It has been proposed that the subspace corresponds to a manifold defined by a kinematic constraint, such that the position of the center of mass (CoM of the whole body is constant in time, referred to as the kinematic uncontrolled manifold (kinematic-UCM. A control strategy related to this hypothesis (CoM-control-strategy claims that the central nervous system (CNS aims to keep the posture close to the kinematic-UCM using a continuous feedback controller, leading to sway patterns that mostly occur within the kinematic-UCM, where no corrective control is exerted. An alternative strategy proposed by the authors (intermittent control-strategy claims that the CNS stabilizes posture by intermittently suspending the active feedback controller, in such a way to allow the CNS to exploit a stable manifold of the saddle-type upright equilibrium in the state-space of the system, referred to as the dynamic-UCM, when the state point is on or near the manifold. Although the mathematical definitions of the kinematic- and dynamic-UCM are completely different, both UCMs play similar roles in the stabilization of multi-joint upright posture. The purpose of this study was to compare the dynamic performance of the two control strategies. In particular, we considered a double-inverted-pendulum-model of postural control, and analyzed the two UCMs defined above. We first showed that the geometric configurations of the two UCMs are almost identical. We then investigated whether the UCM-component of experimental sway could be considered as passive dynamics with no active control, and showed that such UCM-component mainly consists of high frequency oscillations above 1 Hz, corresponding to anti-phase coordination between the ankle and

Mogul-Patterned Elastomeric Substrate for Stretchable Electronics.

Science.gov (United States)

Lee, Han-Byeol; Bae, Chan-Wool; Duy, Le Thai; Sohn, Il-Yung; Kim, Do-Il; Song, You-Joon; Kim, Youn-Jea; Lee, Nae-Eung

2016-04-01

A mogul-patterned stretchable substrate with multidirectional stretchability and minimal fracture of layers under high stretching is fabricated by double photolithography and soft lithography. Au layers and a reduced graphene oxide chemiresistor on a mogul-patterned poly(dimethylsiloxane) substrate are stable and durable under various stretching conditions. The newly designed mogul-patterned stretchable substrate shows great promise for stretchable electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stable Superstring Relics and Ultrahigh Energy Cosmic Rays

CERN Document Server

Coriano, Claudio; Plumacher, Michael; Coriano, Claudio; Faraggi, Alon E.; Plumacher, Michael

2001-01-01

One of the most intriguing experimental results of recent years is the observation of Ultrahigh Energy Cosmic Rays (UHECRs) above the GZK cutoff. Plausible candidates for the UHECR primaries are the decay products of a meta--stable matter state with mass of order O(10^{12-15 GeV}), which simultaneously is a good cold dark matter candidate. We study possible meta-stable matter states that arise from Wilson line breaking of GUT symmetries in semi-realistic heterotic string models. In the models that we study the exotic matter states can be classified according to patterns of SO(10) symmetry breaking. We show that cryptons, which are states that carry fractional electric charge $\\pm1/2$, and are confined by a hidden gauge group cannot produce viable dark matter. This is due to the fact that, in addition to the lightest neutral bound state, cryptons give rise to meta-stable charged bound states. However, these states may still account for the UHECR events. We argue that the uniton, which is an exotic Standard Mod...

A bio-inspired spatial patterning circuit.

Science.gov (United States)

Chen, Kai-Yuan; Joe, Danial J; Shealy, James B; Land, Bruce R; Shen, Xiling

2014-01-01

Lateral Inhibition (LI) is a widely conserved patterning mechanism in biological systems across species. Distinct from better-known Turing patterns, LI depend on cell-cell contact rather than diffusion. We built an in silico genetic circuit model to analyze the dynamic properties of LI. The model revealed that LI amplifies differences between neighboring cells to push them into opposite states, hence forming stable 2-D patterns. Inspired by this insight, we designed and implemented an electronic circuit that recapitulates LI patterning dynamics. This biomimetic system serve as a physical model to elucidate the design principle of generating robust patterning through spatial feedback, regardless of the underlying devices being biological or electrical.

Stable isotope composition of human fingernails from Slovakia

International Nuclear Information System (INIS)

Grolmusová, Zuzana; Rapčanová, Anna; Michalko, Juraj; Čech, Peter; Veis, Pavel

2014-01-01

Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ 13 C and δ 15 N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in 13 C and 15 N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ 13 C and δ 15 N values. These data were compared to previously published δ 13 C and δ 15 N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking. - Highlights: • This study deals with stable isotope analyses of fingernails from Slovak volunteers. • δ 13 C and δ 15 N values of vegetarian and omnivore fingernails were compared. • Influence of sex, diet and smoking was studied

Recent fertility trends in industrialized countries: toward a fluctuating or a stable pattern?

Science.gov (United States)

Day, L H

1995-09-01

The conclusion of this analysis of fertility trends in industrialized countries is that future trends will be evident from accurate data and the inclusion of causal factors such as religion, ethnicity, migration status, marital status, employment status, neighborhood residence, or housing type. Period fertility measures are considered to be unreliable but useful as indicators of potential future changes in fertility. The expectation is that developed countries with low birth rates will have greater fluctuations than trends. Current patterns of fertility in developed countries are thought to have occurred due to substantial control over both the number and the timing of fertility. Patterns in the recent past have reflected further decline, an end to decline and a continued increase, or fluctuation. The most widespread pattern is continued increase following a period of low fertility. This pattern is in evidence in almost every country of northern and western Europe, Canada, the United States, and New Zealand. Countries with continued declines include Japan and eastern and southern European countries, which were the last to experience declines to replacement levels. Countries with fluctuating patterns include Norway, Sweden, and Switzerland. Countries with greater fluctuations include Belgium, Iceland, the former West Germany, the Netherlands, and Poland. The argument is made to not count these patterns as fluctuations due to 1) the similarity in magnitude, timing, and direction; 2) the small changes after the low was reached; and 3) their appearance everywhere at the same time. Stability of rates in the future appears to be a reasonable prospect due to the greater openness about human sexuality and the wider roles for women. Changes have occurred in attitudes about family size in the direction of smaller families, and the range in family size has narrowed considerably. Potential increases may occur due to a new emphasis on family and parenthood, the diminished

Durability and flexibility of chimpanzee grooming patterns during a period of dominance instability.

Science.gov (United States)

Koyama, Nicola F; Ronkainen, Kirsty; Aureli, Filippo

2017-11-01

Growing evidence from studies on primates and other taxa has shown that the maintenance of long-term affiliative patterns influences fitness. Thus, understanding how individuals regulate social interactions in response to environmental and social factors contributes to our understanding of the evolutionary basis of sociality. We investigated the durability of affiliation patterns in chimpanzees across three 3-month periods of varying social uncertainty depending on the degree of stability in the male hierarchy, with a 2-year gap between each period. Periods were unstable (no clear alpha male), recently stable (new alpha male just established) and stable (alpha male in place for 2 years). We focused on three features of social exchange shared by human and non-human primates: consistency of exchanges across periods, durability of preferred partners, and degree of reciprocity in each period. We compared male-to-male, female-to-female, male-to-female, and female-to-male grooming patterns. Overall, more grooming was exchanged in the stable period. Grooming patterns were not consistent across the three periods, but were only consistent between the recently stable and stable periods for female-to-female and male-to-female dyads. As predicted from the opportunistic nature of male relationships, male-to-male grooming was least likely to be correlated across all periods and males had relatively fewer durable (i.e., preferred partners in all periods) same-sex partners than females. Our predictions that grooming reciprocity would be less likely during the unstable period and in male-male dyads were only partially supported. We found grooming reciprocity in all periods for female-female dyads but only in the stable period for male-male and female-male dyads. Although long-term affiliative patterns are well studied in primates, this is the first study to investigate the association between social uncertainty and durability of affiliative patterns. Our findings suggest social

The Effect of Surface Patterning on Corrosion Resistance of Biomedical Devices

Science.gov (United States)

Guo, Mengnan; Toloei, Alisina; Rotermund, Harm H.

2016-10-01

In this study, two styles of surface topographies have been created on stainless steel wires to test their corrosion resistance as simulated implanted biomedical devices. Grade 316 LVM stainless steel wire was initially polished to G1500 surface finish before treatment to produce the two different topographies: 1. Unidirectional roughness was created using SiC papers and 2. Various patterns were created with specific hole diameter and inter-hole spacing using focused ion beam (FIB). In order to simulate the environment of implanted biomedical devices, a three-electrode electrochemical cell with 0.9% (by mass) NaCl solution has been used to test the corrosion resistance of the samples by potentiodynamic polarization test method. SEM and EDS analyzed the appearance and chemical composition of different elements including oxygen on the surface. The potential of stable pitting, time related to the initiation of the stable pitting, and the highest corrosion current associated with stable pitting have been compared for samples with the two styles of topography. It was found that surfaces with patterns have a relatively higher pitting potential and it takes longer time to initiate stable pitting than the surface without any patterns.

Stable one-dimensional periodic waves in Kerr-type saturable and quadratic nonlinear media

International Nuclear Information System (INIS)

Kartashov, Yaroslav V; Egorov, Alexey A; Vysloukh, Victor A; Torner, Lluis

2004-01-01

We review the latest progress and properties of the families of bright and dark one-dimensional periodic waves propagating in saturable Kerr-type and quadratic nonlinear media. We show how saturation of the nonlinear response results in the appearance of stability (instability) bands in a focusing (defocusing) medium, which is in sharp contrast with the properties of periodic waves in Kerr media. One of the key results discovered is the stabilization of multicolour periodic waves in quadratic media. In particular, dark-type waves are shown to be metastable, while bright-type waves are completely stable in a broad range of energy flows and material parameters. This yields the first known example of completely stable periodic wave patterns propagating in conservative uniform media supporting bright solitons. Such results open the way to the experimental observation of the corresponding self-sustained periodic wave patterns

Seasonal variation in water uptake patterns of three plant species based on stable isotopes in the semi-arid Loess Plateau.

Science.gov (United States)

Wang, Jian; Fu, Bojie; Lu, Nan; Zhang, Li

2017-12-31

Water is a limiting factor and significant driving force for ecosystem processes in arid and semi-arid areas. Knowledge of plant water uptake pattern is indispensable for understanding soil-plant interactions and species coexistence. The 'Grain for Green' project that started in 1999 in the Loess Plateau of China has led to large scale vegetation change. However, little is known about the water uptake patterns of the main plant species that inhabit in this region. In this study, the seasonal variations in water uptake patterns of three representative plant species, Stipa bungeana, Artemisia gmelinii and Vitex negundo, that are widely distributed in the semi-arid area of the Loess Plateau, were identified by using dual stable isotopes of δ 2 H and δ 18 O in plant and soil water coupled with a Bayesian mixing model MixSIAR. The soil water at the 0-120cm depth contributed 79.54±6.05% and 79.94±8.81% of the total water uptake of S. bungeana and A. gmelinii, respectively, in the growing season. The 0-40cm soil contributed the most water in July (74.20±15.20%), and the largest proportion of water (33.10±15.20%) was derived from 120-300cm soils in August for A. gmelinii. However, V. negundo obtained water predominantly from surface soil horizons (0-40cm) and then switched to deep soil layers (120-300cm) as the season progressed. This suggested that V. negundo has a greater degree of ecological plasticity as it could explore water sources from deeper soils as the water stress increased. This capacity can mainly be attributed to its functionally dimorphic root system. V. negundo may have a competitive advantage when encountering short-term drought. The ecological plasticity of plant water use needs to be considered in plant species selection and ecological management and restoration of the arid and semi-arid ecosystems in the Loess Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

PENGEMBANGAN MEDIA PEMBELAJARAN IPS SEJARAH MELALUI APLIKASI SWAY BERKONTEN INDIS DI SMP NEGERI 8 MADIUN

Directory of Open Access Journals (Sweden)

Khoirul Huda

2017-08-01

Full Text Available Education in Indonesia is seen from the perspective of the present field experiencing many multicomplex problems. The role of educators in utilizing learning conditions through the composition of teaching tools has not been powerless. Minimnya in designing models, strategies or media that are not adequate. This condition is often seen in SMP Negeri 8 Madiun. Based on the observations mention First, the teaching model of IPS History is still conventional with the lecture method. Educators have not taken advantage of interesting and interactive media variations leading to saturation. Second, the limitations of resource utilization. Whereas the surrounding environment learning source can be used for learning IPS History such as Indis building (Housing Employee KA, SMPN 1 Madiun School Building, City Hall, Giringan PLTA, pagotan sugar factory and kawedanan Uteran or Kandangan coffee garden. The purpose of this research is to develop the media office Sway berkonten Indis to form a draft prototype that has been tested. Research type is Research and Development. The result of this research is limited test at SMP Negeri 10 Madiun got average score 4,23, produce very good score (X => 4,21 so media is considered feasible. The expanded scale test at SMP Negeri 8 Madiun shows the average of 60,35 (pre-test and 94,46 (post-test, and statistic test of Paired Samples T Test. The result of significance value is 0.00, so the result shows less than 0.05 and  means rejected so that there has been a significant increase.

Stable isotopes

International Nuclear Information System (INIS)

Evans, D.K.

1986-01-01

Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

Stable Isotope Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

stableGP

Data.gov (United States)

National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

Stable isotope composition of human fingernails from Slovakia

Energy Technology Data Exchange (ETDEWEB)

Grolmusová, Zuzana, E-mail: zuzana.grolmusova@geology.sk [Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F2, 842 48 Bratislava (Slovakia); State Geological Institute of Dionýz Štúr, Laboratory of Isotope Geology, Mlynská dolina 1, 817 04 Bratislava (Slovakia); Rapčanová, Anna [Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F2, 842 48 Bratislava (Slovakia); Michalko, Juraj; Čech, Peter [State Geological Institute of Dionýz Štúr, Laboratory of Isotope Geology, Mlynská dolina 1, 817 04 Bratislava (Slovakia); Veis, Pavel [Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Department of Experimental Physics, Mlynská dolina F2, 842 48 Bratislava (Slovakia); State Geological Institute of Dionýz Štúr, Laboratory of Isotope Geology, Mlynská dolina 1, 817 04 Bratislava (Slovakia)

2014-10-15

Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ{sup 13}C and δ{sup 15}N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in {sup 13}C and {sup 15}N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ{sup 13}C and δ{sup 15}N values. These data were compared to previously published δ{sup 13}C and δ{sup 15}N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking. - Highlights: • This study deals with stable isotope analyses of fingernails from Slovak volunteers. • δ{sup 13}C and δ{sup 15}N values of vegetarian and omnivore fingernails were compared. • Influence of sex, diet and smoking was studied.

Regional and inter annual patterns of heavy metals, organochlorines and stable isotopes in narwhals (Monodon monoceros) from West Greenland

DEFF Research Database (Denmark)

Dietz, R.; Riget, F.; Hobson, K.A.

2004-01-01

Samples of 150 narwhals obtained in different years from two West Greenland areas, Avanersuaq and Uummannaq, were compared for concentrations of and regional differences in heavy metals and organochlorines and stable-carbon and nitrogen isotopes. Cadmium, Hg, and Se concentrations increased....../age composition of the data. PCB and DDT concentrations in West Greenland narwhals were half those found in East Greenland and Svalbard. Stable-carbon isotope ratios in muscle of 150 narwhals showed a decreasing trend in the first year when they gradually reduced their dependency on mother's milk, after which...... between stable isotope ratios and metal and OC concentrations....

Sway‐dependent changes in standing ankle stiffness caused by muscle thixotropy

Science.gov (United States)

Sakanaka, Tania E.; Lakie, Martin

2016-01-01

Key points The passive stiffness of the calf muscles contributes to standing balance, although the properties of muscle tissue are highly labile.We investigated the effect of sway history upon intrinsic ankle stiffness and demonstrated reductions in stiffness of up to 43% during conditions of increased baseline sway.This sway dependence was most apparent when using low amplitude stiffness‐measuring perturbations, and the short‐range stiffness component was smaller during periods of high sway.These characteristics are consistent with the thixotropic properties of the calf muscles causing the observed changes in ankle stiffness.Periods of increased sway impair the passive stabilization of standing, demanding more active neural control of balance. Abstract Quiet standing is achieved through a combination of active and passive mechanisms, consisting of neural control and intrinsic mechanical stiffness of the ankle joint, respectively. The mechanical stiffness is partly determined by the calf muscles. However, the viscoelastic properties of muscle are highly labile, exhibiting a strong dependence on movement history. By measuring the effect of sway history upon ankle stiffness, the present study determines whether this lability has consequences for the passive stabilization of human standing. Ten subjects stood quietly on a rotating platform whose axis was collinear with the ankle joint. Ankle sway was increased by slowly tilting this platform in a random fashion, or decreased by fixing the body to a board. Ankle stiffness was measured by using the same platform to simultaneously apply small, brief perturbations (ankle stiffness by up to 43% compared to the body‐fixed condition. Normal quiet stance was associated with intermediate values. The effect was most apparent when using smaller perturbation amplitudes to measure stiffness (0.1 vs. 0.6 deg). Furthermore, torque responses exhibited a biphasic pattern, consisting of an initial steep rise followed by a

Computational Model and Numerical Simulation for Submerged Mooring Monitoring Platform’s Dynamical Response

Directory of Open Access Journals (Sweden)

He Kongde

2015-01-01

Full Text Available Computational model and numerical simulation for submerged mooring monitoring platform were formulated aimed at the dynamical response by the action of flow force, which based on Hopkinson impact load theory, taken into account the catenoid effect of mooring cable and revised the difference of tension and tangential direction action force by equivalent modulus of elasticity. Solved the equation by hydraulics theory and structural mechanics theory of oceaneering, studied the response of buoy on flow force. The validity of model were checked and the results were in good agreement; the result show the buoy will engender biggish heave and swaying displacement, but the swaying displacement got stable quickly and the heaven displacement cause vibration for the vortex-induced action by the flow.

Is Sensation Seeking a Stable Trait or Does It Change over Time?

Science.gov (United States)

Lynne-Landsman, Sarah D.; Graber, Julia A.; Nichols, Tracy R.; Botvin, Gilbert J.

2011-01-01

The theory of sensation seeking has conceptualized this construct as a stable personality trait associated with a variety of problem behaviors. Reckless behavior theory posits that increases in reckless behavior during adolescence can be attributed, in part, to increases in sensation seeking. This study evaluated patterns of stability and change…

A model of the transverse modes of stable and unstable porro-prism resonators using symmetry considerations

Science.gov (United States)

Burger, Liesl; Forbes, Andrew

2007-09-01

A simple model of a Porro prism laser resonator has been found to correctly predict the formation of the "petal" mode patterns typical of these resonators. A geometrical analysis of the petals suggests that these petals are the lowest-order modes of this type of resonator. Further use of the model reveals the formation of more complex beam patterns, and the nature of these patterns is investigated. Also, the output of stable and unstable resonator modes is presented.

Leg-adjustment strategies for stable running in three dimensions

International Nuclear Information System (INIS)

Peuker, Frank; Maufroy, Christophe; Seyfarth, André

2012-01-01

The dynamics of the center of mass (CoM) in the sagittal plane in humans and animals during running is well described by the spring-loaded inverted pendulum (SLIP). With appropriate parameters, SLIP running patterns are stable, and these models can recover from perturbations without the need for corrective strategies, such as the application of additional forces. Rather, it is sufficient to adjust the leg to a fixed angle relative to the ground. In this work, we consider the extension of the SLIP to three dimensions (3D SLIP) and investigate feed-forward strategies for leg adjustment during the flight phase. As in the SLIP model, the leg is placed at a fixed angle. We extend the scope of possible reference axes from only fixed horizontal and vertical axes to include the CoM velocity vector as a movement-related reference, resulting in six leg-adjustment strategies. Only leg-adjustment strategies that include the CoM velocity vector produced stable running and large parameter domains of stability. The ability of the model to recover from perturbations along the direction of motion (directional stability) depended on the strategy for lateral leg adjustment. Specifically, asymptotic and neutral directional stability was observed for strategies based on the global reference axis and the velocity vector, respectively. Additional features of velocity-based leg adjustment are running at arbitrary low speed (kinetic energy) and the emergence of large domains of stable 3D running that are smoothly transferred to 2D SLIP stability and even to 1D SLIP hopping. One of the additional leg-adjustment strategies represented a large convex region of parameters where stable and robust hopping and running patterns exist. Therefore, this strategy is a promising candidate for implementation into engineering applications, such as robots, for instance. In a preliminary comparison, the model predictions were in good agreement with the experimental data, suggesting that the 3D SLIP is an

Role of the Frontal Cortex in Standing Postural Sway Tasks While Dual-Tasking: A Functional Near-Infrared Spectroscopy Study Examining Working Memory Capacity

Directory of Open Access Journals (Sweden)

Hiroyuki Fujita

2016-01-01

Full Text Available Posture control during a dual-task involves changing the distribution of attention resources between the cognitive and motor tasks and involves the frontal cortex working memory (WM. The present study aimed to better understand the impact of frontal lobe activity and WM capacity in postural control during a dual-task. High and low WM-span groups were compared using their reading span test scores. High and low WM capacity were compared based on cognitive and balance performance and hemoglobin oxygenation (oxyHb levels during standing during single (S-S, standing during dual (S-D, one leg standing during single (O-S, and one leg standing during dual (O-D tasks. For sway pass length, significant difference in only the O-D task was observed between both groups. oxyHb levels were markedly increased in the right dorsolateral prefrontal cortex and supplementary motor area in the high-span group during a dual-task. Therefore, WM capacity influenced the allocation of attentional resources and motor performance.

Self-esteem Is Mostly Stable Across Young Adulthood: Evidence from Latent STARTS Models.

Science.gov (United States)

Wagner, Jenny; Lüdtke, Oliver; Trautwein, Ulrich

2016-08-01

How stable is self-esteem? This long-standing debate has led to different conclusions across different areas of psychology. Longitudinal data and up-to-date statistical models have recently indicated that self-esteem has stable and autoregressive trait-like components and state-like components. We applied latent STARTS models with the goal of replicating previous findings in a longitudinal sample of young adults (N = 4,532; Mage  = 19.60, SD = 0.85; 55% female). In addition, we applied multigroup models to extend previous findings on different patterns of stability for men versus women and for people with high versus low levels of depressive symptoms. We found evidence for the general pattern of a major proportion of stable and autoregressive trait variance and a smaller yet substantial amount of state variance in self-esteem across 10 years. Furthermore, multigroup models suggested substantial differences in the variance components: Females showed more state variability than males. Individuals with higher levels of depressive symptoms showed more state and less autoregressive trait variance in self-esteem. Results are discussed with respect to the ongoing trait-state debate and possible implications of the group differences that we found in the stability of self-esteem. © 2015 Wiley Periodicals, Inc.

Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras

Directory of Open Access Journals (Sweden)

Autumn Oczkowski

2016-12-01

Full Text Available Stable isotope measurements of nitrogen and carbon (δ15N, δ13C are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is critical to interpreting values in these ecosystems. While base-level isotope data are generally readily available for estuaries, nearshore coastal waters, and the open ocean, the continental shelf is less studied. To address this, and as a first step towards developing a surrogate for base-level isotopic signature in this region, we collected surface and deep water samples from the United States’ eastern continental shelf in the Western Atlantic Ocean, from the Gulf of Maine to Cape Hatteras, periodically between 2000 and 2013. During the study, particulate matter δ15N values ranged from 0.8 to 17.4 ‰, and δ13C values from -26.4 to -15.6 ‰ over the region. We used spatial autocorrelation analysis and random forest modeling to examine the spatial trends and potential environmental drivers of the stable isotope values. We observed general trends towards lower values for both nitrogen and carbon isotopes at the seaward edge of the shelf. Conversely, higher δ15N and δ13C values were observed on the landward edge of the shelf, in particular in the southern portion of the sampling area. Across all sites, the magnitude of the difference between the δ15N of subsurface and surface particulate matter (PM significantly increased with water depth (r2 = 0.41, df = 35, p < 0.001, while δ13C values did not change. There were significant positive correlation between δ15N and δ13C values for surface PM in each of the three marine ecoregions that make up the study area. Stable isotope dynamics on the shelf can inform both nearshore and open ocean research efforts, reflecting regional productivity patterns and, even possibly, large-scale climate fluctuations.

Haptic Cues for Balance: Use of a Cane Provides Immediate Body Stabilization

Directory of Open Access Journals (Sweden)

Stefania Sozzi

2017-12-01

Full Text Available Haptic cues are important for balance. Knowledge of the temporal features of their effect may be crucial for the design of neural prostheses. Touching a stable surface with a fingertip reduces body sway in standing subjects eyes closed (EC, and removal of haptic cue reinstates a large sway pattern. Changes in sway occur rapidly on changing haptic conditions. Here, we describe the effects and time-course of stabilization produced by a haptic cue derived from a walking cane. We intended to confirm that cane use reduces body sway, to evaluate the effect of vision on stabilization by a cane, and to estimate the delay of the changes in body sway after addition and withdrawal of haptic input. Seventeen healthy young subjects stood in tandem position on a force platform, with eyes closed or open (EO. They gently lowered the cane onto and lifted it from a second force platform. Sixty trials per direction of haptic shift (Touch → NoTouch, T-NT; NoTouch → Touch, NT-T and visual condition (EC-EO were acquired. Traces of Center of foot Pressure (CoP and the force exerted by cane were filtered, rectified, and averaged. The position in space of a reflective marker positioned on the cane tip was also acquired by an optoelectronic device. Cross-correlation (CC analysis was performed between traces of cane tip and CoP displacement. Latencies of changes in CoP oscillation in the frontal plane EC following the T-NT and NT-T haptic shift were statistically estimated. The CoP oscillations were larger in EC than EO under both T and NT (p < 0.001 and larger during NT than T conditions (p < 0.001. Haptic-induced effect under EC (Romberg quotient NT/T ~ 1.2 was less effective than that of vision under NT condition (EC/EO ~ 1.5 (p < 0.001. With EO cane had little effect. Cane displacement lagged CoP displacement under both EC and EO. Latencies to changes in CoP oscillations were longer after addition (NT-T, about 1.6 s than withdrawal (T-NT, about 0.9 s of haptic

Tapered composite likelihood for spatial max-stable models

KAUST Repository

Sang, Huiyan

2014-05-01

Spatial extreme value analysis is useful to environmental studies, in which extreme value phenomena are of interest and meaningful spatial patterns can be discerned. Max-stable process models are able to describe such phenomena. This class of models is asymptotically justified to characterize the spatial dependence among extremes. However, likelihood inference is challenging for such models because their corresponding joint likelihood is unavailable and only bivariate or trivariate distributions are known. In this paper, we propose a tapered composite likelihood approach by utilizing lower dimensional marginal likelihoods for inference on parameters of various max-stable process models. We consider a weighting strategy based on a "taper range" to exclude distant pairs or triples. The "optimal taper range" is selected to maximize various measures of the Godambe information associated with the tapered composite likelihood function. This method substantially reduces the computational cost and improves the efficiency over equally weighted composite likelihood estimators. We illustrate its utility with simulation experiments and an analysis of rainfall data in Switzerland.

Tapered composite likelihood for spatial max-stable models

KAUST Repository

Sang, Huiyan; Genton, Marc G.

2014-01-01

Spatial extreme value analysis is useful to environmental studies, in which extreme value phenomena are of interest and meaningful spatial patterns can be discerned. Max-stable process models are able to describe such phenomena. This class of models is asymptotically justified to characterize the spatial dependence among extremes. However, likelihood inference is challenging for such models because their corresponding joint likelihood is unavailable and only bivariate or trivariate distributions are known. In this paper, we propose a tapered composite likelihood approach by utilizing lower dimensional marginal likelihoods for inference on parameters of various max-stable process models. We consider a weighting strategy based on a "taper range" to exclude distant pairs or triples. The "optimal taper range" is selected to maximize various measures of the Godambe information associated with the tapered composite likelihood function. This method substantially reduces the computational cost and improves the efficiency over equally weighted composite likelihood estimators. We illustrate its utility with simulation experiments and an analysis of rainfall data in Switzerland.

Software patterns, knowledge maps, and domain analysis

CERN Document Server

Fayad, Mohamed E; Hegde, Srikanth GK; Basia, Anshu; Vakil, Ashka

2014-01-01

Preface AcknowledgmentsAuthors INTRODUCTIONAn Overview of Knowledge MapsIntroduction: Key Concepts-Software Stable Models, Knowledge Maps, Pattern Language, Goals, Capabilities (Enduring Business Themes + Business Objects) The Motivation The Problem The Objectives Overview of Software Stability Concepts Overview of Knowledge Maps Pattern Languages versus Knowledge Maps: A Brief ComparisonThe Solution Knowledge Maps Methodology or Concurrent Software Development ModelWhy Knowledge Maps? Research Methodology Undertaken Research Verification and Validation The Stratification of This Book Summary

On Oscillatory Pattern of Malaria Dynamics in a Population with Temporary Immunity

Directory of Open Access Journals (Sweden)

J. Tumwiine

2007-01-01

Full Text Available We use a model to study the dynamics of malaria in the human and mosquito population to explain the stability patterns of malaria. The model results show that the disease-free equilibrium is globally asymptotically stable and occurs whenever the basic reproduction number, R0 is less than unity. We also note that when R0>1, the disease-free equilibrium is unstable and the endemic equilibrium is stable. Numerical simulations show that recoveries and temporary immunity keep the populations at oscillation patterns and eventually converge to a steady state.

Uptake of radionuclides and stable elements from paddy soil to rice: a review

International Nuclear Information System (INIS)

Uchida, S.; Tagami, K.; Shang, Z.R.; Choi, Y.H.

2009-01-01

The critical paths for radionuclides and the critical foods in Asian countries differ from those in Western countries because agricultural products and diets are different. Consequently, safety assessments for Asian countries must consider rice as a critical food. As most rice is produced under flooded conditions, the uptake of radionuclides by rice is affected by soil conditions. In this report, we summarize radionuclide and stable element soil-to-plant transfer factors (TFs) for rice. Field observation results for fallout 137 Cs and stable Cs TFs indicated that while fallout 137 Cs had higher TF than stable Cs over several decades, the GM (geometric mean) values were similar with the GM of TF value for 137 Cs being 3.6 x 10 -3 and that for stable Cs being 2.5 x 10 -3 . Although there are some limitations to the use of TF for stable elements under some circumstances, these values can be used to evaluate long-term transfer of long-lived radionuclides in the environment. The compiled data showed that TF values were higher in brown rice than in white rice because distribution patterns for elements were different in the bran and white parts of rice grains.

Effect of expertise in shooting and Taekwondo on bipedal and unipedal postural control isolated or concurrent with a reaction-time task.

Science.gov (United States)

Negahban, Hossein; Aryan, Najmolhoda; Mazaheri, Masood; Norasteh, Ali Asghar; Sanjari, Mohammad Ali

2013-06-01

It was hypothesized that training in 'static balance' or 'dynamic balance' sports has differential effects on postural control and its attention demands during quiet standing. In order to test this hypothesis, two groups of female athletes practicing shooting, as a 'static balance' sport, and Taekwondo, as a 'dynamic balance' sport, and a control group of non-physically active females voluntarily participated in this study. Postural control was assessed during bipedal and unipedal stance with and without performing a Go/No-go reaction time task. Visual and/or support surface conditions were manipulated in bipedal and unipedal stances in order to modify postural difficulty. Mixed model analysis of variance was used to determine the effects of dual tasking on postural and cognitive performance. Similar pattern of results were found in bipedal and unipedal stances, with Taekwondo practitioners displaying larger sway, shooters displaying lower sway and non-athletes displaying sway characteristics intermediate to Taekwondo and shooting athletes. Larger effect was found in bipedal stance. Single to dual-task comparison of postural control showed no significant effect of mental task on sway velocity in shooters, indicating less cognitive effort invested in balance control during bipedal stance. We suggest that expertise in shooting has a more pronounced effect on decreased sway in static balance conditions. Furthermore, shooters invest less attention in postures that are more specific to their training, i.e. bipedal stance. Copyright © 2012 Elsevier B.V. All rights reserved.

Examining the stability of dual-task posture and reaction time measures in older adults over five sessions: a pilot study.

Science.gov (United States)

Jehu, Deborah A; Paquet, Nicole; Lajoie, Yves

2016-12-01

Improved performance may be inherent due to repeated exposure to a testing protocol. However, limited research has examined this phenomenon in postural control. The aim was to determine the influence of repeated administration of a dual-task testing protocol once per week for 5 weeks on postural sway and reaction time. Ten healthy older adults (67.0 ± 6.9 years) stood on a force plate for 30 s in feet apart and semi-tandem positions while completing simple reaction time (SRT) and choice reaction time (CRT) tasks. They were instructed to stand as still as possible while verbally responding as fast as possible to the stimuli. No significant differences in postural sway were shown over time (p > 0.05). A plateau in average CRT emerged as the time effect revealed longer CRT during session 1 compared to sessions 3-5 (p task context. Postural sway and SRT were stable over the 5 testing sessions, but variability of CRT continued to improve over time. These findings form a basis for future studies to examine performance-related improvements due to repeated exposure to a testing protocol in a dual-task setting.

Network patterns in exponentially growing two-dimensional biofilms

Science.gov (United States)

Zachreson, Cameron; Yap, Xinhui; Gloag, Erin S.; Shimoni, Raz; Whitchurch, Cynthia B.; Toth, Milos

2017-10-01

Anisotropic collective patterns occur frequently in the morphogenesis of two-dimensional biofilms. These patterns are often attributed to growth regulation mechanisms and differentiation based on gradients of diffusing nutrients and signaling molecules. Here, we employ a model of bacterial growth dynamics to show that even in the absence of growth regulation or differentiation, confinement by an enclosing medium such as agar can itself lead to stable pattern formation over time scales that are employed in experiments. The underlying mechanism relies on path formation through physical deformation of the enclosing environment.

Fingertip touch improves postural stability in patients with peripheral neuropathy.

Science.gov (United States)

Dickstein, R; Shupert, C L; Horak, F B

2001-12-01

The purpose of this work was to determine whether fingertip touch on a stable surface could improve postural stability during stance in subjects with somatosensory loss in the feet from diabetic peripheral neuropathy. The contribution of fingertip touch to postural stability was determined by comparing postural sway in three touch conditions (light, heavy and none) in eight patients and eight healthy control subjects who stood on two surfaces (firm or foam) with eyes open or closed. In the light touch condition, fingertip touch provided only somatosensory information because subjects exerted less than 1 N of force with their fingertip to a force plate, mounted on a vertical support. In the heavy touch condition, mechanical support was available because subjects transmitted as much force to the force plate as they wished. In the no touch condition, subjects held the right forefinger above the force plate. Antero-posterior (AP) and medio-lateral (ML) root mean square (RMS) of center of pressure (CoP) sway and trunk velocity were larger in subjects with somatosensory loss than in control subjects, especially when standing on the foam surface. The effects of light and heavy touch were similar in the somatosensory loss and control groups. Fingertip somatosensory input through light touch attenuated both AP and ML trunk velocity as much as heavy touch. Light touch also reduced CoP sway compared to no touch, although the decrease in CoP sway was less effective than with heavy touch, particularly on the foam surface. The forces that were applied to the touch plate during light touch preceded movements of the CoP, lending support to the suggestion of a feedforward mechanism in which fingertip inputs trigger the activation of postural muscles for controlling body sway. These results have clinical implications for understanding how patients with peripheral neuropathy may benefit from a cane for postural stability in stance.

Tai Chi training reduced coupling between respiration and postural control.

Science.gov (United States)

Holmes, Matthew L; Manor, Brad; Hsieh, Wan-hsin; Hu, Kun; Lipsitz, Lewis A; Li, Li

2016-01-01

In order to maintain stable upright stance, the postural control system must account for the continuous perturbations to the body's center-of-mass including those caused by spontaneous respiration. Both aging and disease increase "posturo-respiratory synchronization;" which reflects the degree to which respiration affects postural sway fluctuations over time. Tai Chi training emphasizes the coordination of respiration and bodily movements and may therefore optimize the functional interaction between these two systems. The purpose of the project was to examine the effect of Tai Chi training on the interaction between respiration and postural control in older adults. We hypothesized that Tai Chi training would improve the ability of the postural control system to compensate for respiratory perturbations and thus, reduce posturo-respiratory synchronization. Participants were recruited from supportive housing facilities and randomized to a 12-week Tai Chi intervention (n=28; 86 ± 5 yrs) or educational-control program (n=34, 85 ± 6 yrs). Standing postural sway and respiration were simultaneously recorded with a force plate and respiratory belt under eyes-open and eyes-closed conditions. Posturo-respiratory synchronization was determined by quantifying the variation of the phase relationship between the dominant oscillatory mode of respiration and corresponding oscillations within postural sway. Groups were similar in age, gender distribution, height, body mass, and intervention compliance. Neither intervention altered average sway speed, sway magnitude or respiratory rate. As compared to the education-control group, however, Tai Chi training reduced posturo-respiratory synchronization when standing with eyes open or closed (ppostural control or respiration, yet reduced the coupling between respiration and postural control. The beneficial effects of Tai Chi training may therefore stem in part from optimization of this multi-system interaction. Copyright © 2015

Influence of forest disturbance on stable nitrogen isotope ratios in soil and vegetation profiles

Science.gov (United States)

Jennifer D. Knoepp; Scott R. Taylor; Lindsay R. Boring; Chelcy F. Miniat

2015-01-01

Soil and plant stable nitrogen isotope ratios (15 N) are influenced by atmospheric nitrogen (N) inputs and processes that regulate organic matter (OM) transformation and N cycling. The resulting 15N patterns may be useful for discerning ecosystem differences in N cycling. We studied two ecosystems; longleaf pine wiregrass (...

Changes of postural control and muscle activation pattern in response to external perturbations after neck flexor fatigue in young subjects with and without chronic neck pain.

Science.gov (United States)

Cheng, Chih-Hsiu; Chien, Andy; Hsu, Wei-Li; Yen, Ling-Wei; Lin, Yang-Hua; Cheng, Hsin-Yi Kathy

2015-03-01

Previous studies have identified sensorimotor disturbances and greater fatigability of neck muscles in patients with neck pain. The purpose of this study was to investigate the effect of neck pain and neck flexor fatigue on standing balance following postural perturbations. Twenty patients with chronic neck pain (CNP) (24.7±3.6 year-old) and 20 age-matched asymptomatic subjects (22.1±2.2 year-old) were recruited. Subjects stood barefoot on a force plate and experienced backward perturbations before and after neck flexor fatigue. Center of pressure, electromyography of cervical and lumbar muscles, and head/trunk accelerations were recorded. Two-way ANOVA (pain×fatigue) was used for statistical analysis. CNP group showed larger body sway during quiet standing but not during perturbed standing compared with asymptomatic adults. In both groups, neck flexor fatigue resulted in greater body sway during the quiet standing but smaller body sway during perturbed standing, increased neck muscle activations and decreased lumbar muscle activations, as well as increased time to maximal head acceleration. Disturbed balance control was observed in CNP patients during the quiet standing. However, a rigid strategy was used to minimize the postural sway and to protect the head against backward perturbations in both CNP and asymptomatic young adults after neck flexor fatigue. The results facilitate the understanding of how the subjects with chronic neck pain and with neck muscle fatigue deal with the challenging condition. Further studies are needed to verify if such phenomenon could be changed after the intervention of specific flexor muscle retraining and balance control exercises. Copyright © 2015 Elsevier B.V. All rights reserved.

THE COMPARISON OF THE LUMBAR MULTIFIDUS MUSCLES FUNCTION BETWEEN GYMNASTIC ATHLETES WITH SWAY-BACK POSTURE AND NORMAL POSTURE.

Science.gov (United States)

Mahdavie, Elnaz; Rezasoltani, Asghar; Simorgh, Leila

2017-08-01

The prevalence of sway back posture (SBP) is very high among elite gymnasts. This posture may be partly due to the improper function of lumbar multifidus muscles (LMM) as lumbar stabilizers muscles. The aim of this study was to compare the thicknesses of LMM measured at rest and during the contraction elicited during an arm lift between elite gymnasts with SBP and normal posture. Observational, descriptive, comparative. The participants consist of twenty gymnasts between the ages of 17 and 30 who had trained in gymnastics for more than ten years. They were assigned to two groups: SBP (n=10) and control (n=10). Posture analysis with grid paper and plumb line was performed for all subjects. The thickness of LMM on dominant side of spinal column was measured by a real-time ultrasound at five lumbar levels. The thickness of the LMM was measured both at rest and during the contraction elicited during an arm lift. The variation between the LMM thickness between the muscle at rest and muscle at the peak of contraction was regarded as LMM muscle function. The thickness of LMM was less in SBP group than the control group at all lumbar segments. The variation in LMM thickness between the state of rest and muscle contraction was significantly less in athletes with SBP than controls when compared at all levels of the lumbar spine (p antigravity and stabilizing muscle group was decreased during arm raising in gymnasts with SBP. 3a.

Situation of nuclear power generation in Sweden: swaying nuclear energy policy and conversion from nuclear phase-out policy

International Nuclear Information System (INIS)

Kuroda, Yuji

2017-01-01

In Sweden, fossil fuels cannot be produced domestically, and most of them depend on foreign imports. For this reason, together with hydropower generation using abundant water resources, nuclear power generation was introduced and used since the early stage. Nuclear power generation in 2015 reached 35% of total generated power energy. As of 2016, Sweden was steadily constructing the world's second final disposal site of high-level radioactive waste. On the other hand, this country is known as the one that decided nuclear phase-out policy earliest in the world. However, the country's nuclear policy is swaying together with changes in political party power due to election results. In 1980, they decided the policy of abolishing all nuclear power generation by 2010. Thereafter, the nuclear phase-out policy was frozen and maximum 10 units of nuclear plants were accepted. The goal of the latest policy is to allow new construction up to 10 units as replacement, and to use 100% of renewable energy in 2040. However, the year of 2040 is not a deadline for the abolishment of nuclear power generation. In Sweden's public opinion on nuclear power generation, the early abolition was dominant at about 50% during 1986∼1995, but this opinion decreased to about 10% in the 2000s. There is an increasing number of opinions saying that the existing nuclear plants should be continuously operated for a while, and phased out step by step in the future. (A.O.)

Pattern formation in superdiffusion Oregonator model

Science.gov (United States)

Feng, Fan; Yan, Jia; Liu, Fu-Cheng; He, Ya-Feng

2016-10-01

Pattern formations in an Oregonator model with superdiffusion are studied in two-dimensional (2D) numerical simulations. Stability analyses are performed by applying Fourier and Laplace transforms to the space fractional reaction-diffusion systems. Antispiral, stable turing patterns, and travelling patterns are observed by changing the diffusion index of the activator. Analyses of Floquet multipliers show that the limit cycle solution loses stability at the wave number of the primitive vector of the travelling hexagonal pattern. We also observed a transition between antispiral and spiral by changing the diffusion index of the inhibitor. Project supported by the National Natural Science Foundation of China (Grant Nos. 11205044 and 11405042), the Research Foundation of Education Bureau of Hebei Province, China (Grant Nos. Y2012009 and ZD2015025), the Program for Young Principal Investigators of Hebei Province, China, and the Midwest Universities Comprehensive Strength Promotion Project.

Unstable patterns and robust synchronization in a model of motor pathway in birdsong

International Nuclear Information System (INIS)

Moukam Kakmeni, F.M.; Bowong, S.; Nana, L.; Kofane, T.C.

2006-10-01

This paper investigates the fundamental dynamical mechanism responsible for transition to chaos in periodically modulated Duffing-Van der Pol oscillator. It is shown that a modulationally unstable pattern appears into an initially stable motionless state. A further spatiotemporal transition occurs with a sharp interface from the selected stable pattern to a stabilized pattern or chaotic state. Also, the synchronization of the chaotic state of the model is investigated. The results are discussed in the context of generalized synchronization. The main idea is to construct an augmented dynamical system from the synchronization error system, which is itself uncertain. The advantage of this method over existing results is that the synchronization time is explicitly computed. Numerical simulations are provided to verify the operation of the proposed algorithm. (author)

A neural interface provides long-term stable natural touch perception.

Science.gov (United States)

Tan, Daniel W; Schiefer, Matthew A; Keith, Michael W; Anderson, James Robert; Tyler, Joyce; Tyler, Dustin J

2014-10-08

Touch perception on the fingers and hand is essential for fine motor control, contributes to our sense of self, allows for effective communication, and aids in our fundamental perception of the world. Despite increasingly sophisticated mechatronics, prosthetic devices still do not directly convey sensation back to their wearers. We show that implanted peripheral nerve interfaces in two human subjects with upper limb amputation provided stable, natural touch sensation in their hands for more than 1 year. Electrical stimulation using implanted peripheral nerve cuff electrodes that did not penetrate the nerve produced touch perceptions at many locations on the phantom hand with repeatable, stable responses in the two subjects for 16 and 24 months. Patterned stimulation intensity produced a sensation that the subjects described as natural and without "tingling," or paresthesia. Different patterns produced different types of sensory perception at the same location on the phantom hand. The two subjects reported tactile perceptions they described as natural tapping, constant pressure, light moving touch, and vibration. Changing average stimulation intensity controlled the size of the percept area; changing stimulation frequency controlled sensation strength. Artificial touch sensation improved the subjects' ability to control grasping strength of the prosthesis and enabled them to better manipulate delicate objects. Thus, electrical stimulation through peripheral nerve electrodes produced long-term sensory restoration after limb loss. Copyright © 2014, American Association for the Advancement of Science.

Preliminary evaluation of prototype footwear and insoles to optimise balance and gait in older people.

Science.gov (United States)

Menz, Hylton B; Auhl, Maria; Munteanu, Shannon E

2017-09-11

Footwear has the potential to influence balance in either a detrimental or beneficial manner, and is therefore an important consideration in relation to falls prevention. The objective of this study was to evaluate balance ability and gait patterns in older women while wearing prototype footwear and insoles designed to improve balance. Older women (n = 30) aged 65 - 83 years (mean 74.4, SD 5.6) performed a series of laboratory tests of balance ability (postural sway on a foam rubber mat, limits of stability and tandem walking, measured with the Neurocom® Balance Master) and gait patterns (walking speed, cadence, step length and step width at preferred speed, measured with the GAITRite® walkway) while wearing (i) flexible footwear (Dunlop Volley™), (ii) their own footwear, and (iii) prototype footwear and insoles designed to improve dynamic balance. Perceptions of the footwear were also documented using a structured questionnaire. There was no difference in postural sway, limits of stability or gait patterns between the footwear conditions. However, when performing the tandem walking test, there was a significant reduction in step width and end sway when wearing the prototype footwear compared to both the flexible footwear and participants' own footwear. Participants perceived their own footwear to be more attractive, comfortable, well-fitted and easier to put on and off compared to the prototype footwear. Despite this, most participants (n = 18, 60%) reported that they would consider wearing the prototype footwear to reduce their risk of falling. The prototype footwear and insoles used in this study improve balance when performing a tandem walk test, as evidenced by a narrower step width and decreased sway at completion of the task. However, further development of the design is required to make the footwear acceptable to older women from the perspective of aesthetics and comfort. Australian New Zealand Clinical Trials Registry. ACTRN12617001128381 , 01

Stable water isotope and surface heat flux simulation using ISOLSM: Evaluation against in-situ measurements

KAUST Repository

Cai, Mick Y.; Wang, Lixin; Parkes, Stephen; Strauss, Josiah; McCabe, Matthew; Evans, Jason P.; Griffiths, Alan D.

2015-01-01

The stable isotopes of water are useful tracers of water sources and hydrological processes. Stable water isotope-enabled land surface modeling is a relatively new approach for characterizing the hydrological cycle, providing spatial and temporal variability for a number of hydrological processes. At the land surface, the integration of stable water isotopes with other meteorological measurements can assist in constraining surface heat flux estimates and discriminate between evaporation (E) and transpiration (T). However, research in this area has traditionally been limited by a lack of continuous in-situ isotopic observations. Here, the National Centre for Atmospheric Research stable isotope-enabled Land Surface Model (ISOLSM) is used to simulate the water and energy fluxes and stable water isotope variations. The model was run for a period of one month with meteorological data collected from a coastal sub-tropical site near Sydney, Australia. The modeled energy fluxes (latent heat and sensible heat) agreed reasonably well with eddy covariance observations, indicating that ISOLSM has the capacity to reproduce observed flux behavior. Comparison of modeled isotopic compositions of evapotranspiration (ET) against in-situ Fourier Transform Infrared spectroscopy (FTIR) measured bulk water vapor isotopic data (10. m above the ground), however, showed differences in magnitude and temporal patterns. The disparity is due to a small contribution from local ET fluxes to atmospheric boundary layer water vapor (~1% based on calculations using ideal gas law) relative to that advected from the ocean for this particular site. Using ISOLSM simulation, the ET was partitioned into E and T with 70% being T. We also identified that soil water from different soil layers affected T and E differently based on the simulated soil isotopic patterns, which reflects the internal working of ISOLSM. These results highlighted the capacity of using the isotope-enabled models to discriminate

Stable water isotope and surface heat flux simulation using ISOLSM: Evaluation against in-situ measurements

KAUST Repository

Cai, Mick Y.

2015-04-01

The stable isotopes of water are useful tracers of water sources and hydrological processes. Stable water isotope-enabled land surface modeling is a relatively new approach for characterizing the hydrological cycle, providing spatial and temporal variability for a number of hydrological processes. At the land surface, the integration of stable water isotopes with other meteorological measurements can assist in constraining surface heat flux estimates and discriminate between evaporation (E) and transpiration (T). However, research in this area has traditionally been limited by a lack of continuous in-situ isotopic observations. Here, the National Centre for Atmospheric Research stable isotope-enabled Land Surface Model (ISOLSM) is used to simulate the water and energy fluxes and stable water isotope variations. The model was run for a period of one month with meteorological data collected from a coastal sub-tropical site near Sydney, Australia. The modeled energy fluxes (latent heat and sensible heat) agreed reasonably well with eddy covariance observations, indicating that ISOLSM has the capacity to reproduce observed flux behavior. Comparison of modeled isotopic compositions of evapotranspiration (ET) against in-situ Fourier Transform Infrared spectroscopy (FTIR) measured bulk water vapor isotopic data (10. m above the ground), however, showed differences in magnitude and temporal patterns. The disparity is due to a small contribution from local ET fluxes to atmospheric boundary layer water vapor (~1% based on calculations using ideal gas law) relative to that advected from the ocean for this particular site. Using ISOLSM simulation, the ET was partitioned into E and T with 70% being T. We also identified that soil water from different soil layers affected T and E differently based on the simulated soil isotopic patterns, which reflects the internal working of ISOLSM. These results highlighted the capacity of using the isotope-enabled models to discriminate

One-dimensional stable distributions

CERN Document Server

Zolotarev, V M

1986-01-01

This is the first book specifically devoted to a systematic exposition of the essential facts known about the properties of stable distributions. In addition to its main focus on the analytic properties of stable laws, the book also includes examples of the occurrence of stable distributions in applied problems and a chapter on the problem of statistical estimation of the parameters determining stable laws. A valuable feature of the book is the author's use of several formally different ways of expressing characteristic functions corresponding to these laws.

Is parricide a stable phenomenon? An analysis of parricide offenders in a forensic hospital

Directory of Open Access Journals (Sweden)

Lisieux Elaine de Borba-Telles

2017-01-01

Conclusions: Regarding weapon usage and the characteristics of victims and offenders, the observed pattern is consistent with previous researches, which allows concluding that the phenomenon of parricide is relatively stable and homogeneous. A forensic psychiatric evaluation of parricide offenders should be warranted given the high prevalence of mental illness among them.

Bi-stable optical actuator

Science.gov (United States)

Holdener, Fred R.; Boyd, Robert D.

2000-01-01

The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

Remarks on stable and quasi-stable k-strings at large N

International Nuclear Information System (INIS)

Armoni, A.; Shifman, M.

2003-01-01

We discuss k-strings in the large-N Yang-Mills theory and its supersymmetric extension. Whereas the tension of the bona fide (stable) QCD string is expected to depend only on the N-ality of the representation, tensions that depend on specific representation R are often reported in the lattice literature. In particular, adjoint strings are discussed and found in certain simulations. We clarify this issue by systematically exploiting the notion of the quasi-stable strings which becomes well-defined at large N. The quasi-stable strings with representation-dependent tensions decay, but the decay rate (per unit length per unit time) is suppressed as Λ 2 F(N) where F(N) falls off as a function of N. It can be determined on the case-by-case basis. The quasi-stable strings eventually decay into stable strings whose tension indeed depends only on the N-ality. We also briefly review large-N arguments showing why the Casimir formula for the string tension cannot be correct, and present additional arguments in favor of the sine formula. Finally, we comment on the relevance of our estimates to Euclidean lattice measurements

Investigating differences in light stable isotopes between Thai jasmine rice and Sungyod rice

Science.gov (United States)

Kukusamude, C.; Kongsri, S.

2017-10-01

We report the differences in light stable isotopes between two kinds of Thai rice (Thai jasmine and Sungyod rice). Thai jasmine rice and Sungyod rice were cultivated in the northeast and the south of Thailand. Light isotopes including 13C, 15N and 18O of Thai jasmine rice and Sungyod rice samples were carried out using isotope ratio mass spectrometry (IRMS). Thai jasmine rice (Khao Dawk Mali 105) was cultivated from Thung Kula Rong Hai area, whereas Sungyod rice was cultivated from Phathalung province. Hypothesis testing of difference of each isotope between Thai jasmine rice and Sungyod rice was also studied. The study was the feasibility test whether the light stable isotopes can be the variables to identify Thai jasmine rice and Sungyod rice. The result shows that there was difference in the isotope patterns of Thai jasmine rice and Sungyod rice. Our results may provide the useful information in term of stable isotope profiles of Thai rice.

Evolutionary Stable Strategy

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General Article Volume 21 Issue 9 September 2016 pp 803- ... Keywords. Evolutionary game theory, evolutionary stable state, conflict, cooperation, biological games.

Stable Isotopic Analysis on Water Utilization of Two Xerophytic Shrubs in a Revegetated Desert Area: Tengger Desert, China

OpenAIRE

Lei Huang; Zhishan Zhang

2015-01-01

Stable isotope studies on stable isotope ratios of hydrogen and oxygen in water within plants provide new information on water sources and water use patterns under natural conditions. In this study, the sources of water uptake for two typical xerophytic shrubs, Caragana korshinskii and Artemisia ordosica, were determined at four different-aged revegetated sites (1956, 1964, 1981, and 1987) in the Tengger Desert, a revegetated desert area in China. Samples from precipitation, soil water at dif...

Food-web inferences of stable isotope spatial patterns in copepods and yellowfin tuna in the pelagic eastern Pacific Ocean

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Olson, Robert J.; Popp, Brian N.; Graham, Brittany S.; López-Ibarra, Gladis A.; Galván-Magaña, Felipe; Lennert-Cody, Cleridy E.; Bocanegra-Castillo, Noemi; Wallsgrove, Natalie J.; Gier, Elizabeth; Alatorre-Ramírez, Vanessa; Ballance, Lisa T.; Fry, Brian

2010-07-01

Evaluating the impacts of climate and fishing on oceanic ecosystems requires an improved understanding of the trophodynamics of pelagic food webs. Our approach was to examine broad-scale spatial relationships among the stable N isotope values of copepods and yellowfin tuna ( Thunnus albacares), and to quantify yellowfin tuna trophic status in the food web based on stable-isotope and stomach-contents analyses. Using a generalized additive model fitted to abundance-weighted-average δ 15N values of several omnivorous copepod species, we examined isotopic spatial relationships among yellowfin tuna and copepods. We found a broad-scale, uniform gradient in δ 15N values of copepods increasing from south to north in a region encompassing the eastern Pacific warm pool and parts of several current systems. Over the same region, a similar trend was observed for the δ 15N values in the white muscle of yellowfin tuna caught by the purse-seine fishery, implying limited movement behavior. Assuming the omnivorous copepods represent a proxy for the δ 15N values at the base of the food web, the isotopic difference between these two taxa, “ ΔYFT-COP,” was interpreted as a trophic-position offset. Yellowfin tuna trophic-position estimates based on their bulk δ 15N values were not significantly different than independent estimates based on stomach contents, but are sensitive to errors in the trophic enrichment factor and the trophic position of copepods. An apparent inshore-offshore, east to west gradient in yellowfin tuna trophic position was corroborated using compound-specific isotope analysis of amino acids conducted on a subset of samples. The gradient was not explained by the distribution of yellowfin tuna of different sizes, by seasonal variability at the base of the food web, or by known ambit distances (i.e. movements). Yellowfin tuna stomach contents did not show a regular inshore-offshore gradient in trophic position during 2003-2005, but the trophic

Experimental study on flame pattern formation and combustion completeness in a radial microchannel

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Fan, Aiwu; Minaev, Sergey; Kumar, Sudarshan; Liu, Wei; Maruta, Kaoru

2007-12-01

Combustion behavior in a radial microchannel with a gap of 2.0 mm and a diameter of 50 mm was experimentally investigated. In order to simulate the heat recirculation, which is an essential strategy in microscale combustion devices, positive temperature gradients along the radial flow direction were given to the microchannel by an external heat source. A methane-air mixture was supplied from the center of the top plate through a 4.0 mm diameter delivery tube. A variety of flame patterns, including a stable circular flame and several unstable flame patterns termed unstable circular flame, single and double pelton-like flames, traveling flame and triple flame, were observed in the experiments. The regime diagram of all these flame patterns is presented in this paper. Some characteristics of the various flame patterns, such as the radii of stable and unstable circular flames, major combustion products and combustion efficiencies of all these flame patterns, were also investigated. Furthermore, the effect of the heat recirculation on combustion stability was studied by changing the wall temperature levels.

Group living in squamate reptiles: a review of evidence for stable aggregations.

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Gardner, Michael G; Pearson, Sarah K; Johnston, Gregory R; Schwarz, Michael P

2016-11-01

How sociality evolves and is maintained remains a key question in evolutionary biology. Most studies to date have focused on insects, birds, and mammals but data from a wider range of taxonomic groups are essential to identify general patterns and processes. The extent of social behaviour among squamate reptiles is under-appreciated, yet they are a promising group for further studies. Living in aggregations is posited as an important step in the evolution of more complex sociality. We review data on aggregations among squamates and find evidence for some form of aggregations in 94 species across 22 families. Of these, 18 species across 7 families exhibited 'stable' aggregations that entail overlapping home ranges and stable membership in long-term (years) or seasonal aggregations. Phylogenetic analysis suggests that stable aggregations have evolved multiple times in squamates. We: (i) identify significant gaps in our understanding; (ii) outline key traits which should be the focus of future research; and (iii) outline the potential for utilising reproductive skew theory to provide insights into squamate sociality. © 2015 Cambridge Philosophical Society.

The use of stable isotopes for studies on the physiology of plants

International Nuclear Information System (INIS)

Moyse, Alexis.

1982-01-01

The use of the stable isotopes 15 N, 18 O, 13 C for studies on the physiology of plants especially of plants grown under natural environment conditions is reviewed. Analysis of isotopic discrimination give estimates of the various patterns of carbon and nitrogen nutrition and of the rate of water circulation. The method can also be used for paleoclimatology and for the detection of frauds in food products [fr

Diet-tissue stable isotope (delta¹³C and delta¹⁵N) discrimination factors for multiple tissues from terrestrial reptiles (rock iguanas, Cyclura species)

OpenAIRE

Steinitz, Ronnie

2015-01-01

Trophic interactions can drive community structure; therefore, studying food webs is key in understanding ecological communities. Stable isotope analysis is a powerful tool for reconstructing foraging patterns. However, stable isotope discrimination factors (delta¹³C and delta¹⁵N) are needed to best use this tool. We determined the first delta¹³C and delta¹⁵N values for Rock Iguanas (Cyclura spp.) to better understand isotope fractionation patterns in reptiles and estimate wild reptile diets....

[Applications of stable isotope analysis in the trophic ecology studies of cephalopods].

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Li, Yun-Kai; Gong, Yi; Chen, Xin-Jun

2014-05-01

Cephalopods play an important role in marine food webs, however, knowledge about their complex life history, especially their feeding ecology, remains limited. With the rapidly increasing use of stable isotope analysis (SIA) in ecology, it becomes a powerful tool and complement of traditional methods for investigating the trophic ecology and migration patterns of invertebrates. Here, after summarizing the current methods for trophic ecology investigation of cephalopods, applications of SIA in studying the trophic ecology of cephalopods were reviewed, including the key issues such as standardization of available tissues for SIA analyzing, diet shift and migration patterns of cephalopods, with the aim of advancing its application in the biology of cephalopods in the future.

Long-distance Dispersal Patterns of Male Cerulean Warblers (Dendroica cerulea Measured by Stable-hydrogen Isotopes

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M. Katherine. Girvan

2007-12-01

Full Text Available Despite the fundamental role played by long-distance dispersal in population dynamics, the mechanisms promoting or inhibiting dispersal by migratory songbirds are poorly understood. We used stable-hydrogen isotopes (δD to evaluate several hypotheses related to long-distance dispersal in the Cerulean Warbler (Dendroica cerulea, a migratory songbird at the center of considerable conservation attention. Feather samples were collected from 103 males throughout the breeding range. We assumed feathers were molted in late summer on the breeding grounds and thus δD values provided an estimate of breeding or hatching location for the previous year. We used a likelihood-based assignment test to estimate the origin of birds the previous year and derived expected δD values for the entire Cerulean Warbler breeding range from precipitation-based maps. Using Bayes' Rule, we also incorporated a prior probability of breeding origin based on estimated rates of site fidelity and survival between breeding seasons. We found that long-distance breeding dispersal by adult male Cerulean Warblers was a fairly common occurrence with 20 of 71 (28.2% individuals originating from a region other than the one they were sampled in. Surprisingly, long-distance natal dispersal was uncommon; only three of 32 (9.4% second-year birds were estimated to have hatched in a region outside their capture region. Young males may be using a form of post-fledging prospecting or conspecific attraction when selecting their first breeding habitats. Populations on the breeding range periphery, such as Ontario and Tennessee, tended to receive fewer long-distance dispersers than did other regions but produced more dispersing individuals than did core regions, suggesting that these areas could act as important sources for other regions. The tendency of a region to produce dispersing individuals was not significantly related to its relative abundance, implying that population abundance is not a

Preparation of conductive Cu patterns by directly writing using nano-Cu ink

Energy Technology Data Exchange (ETDEWEB)

Li, Wei [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Li, Wenjiang; Wei, Jun [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Tan, Junjun [School of Chemical and Materials and Engineering, Hubei University of Technology, Hubei 435003 (China); Chen, Minfang, E-mail: mfchentj@126.com [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2014-07-01

Conductive and air-stable Cu patterns were directly made on ordinary photo paper using a roller pen filled with nano-Cu ink, which was mainly composed of metallic Cu nanoparticles (NPs) capped with poly(N-vinylpyrrolidone) (PVP). The nano-Cu NPs were obtained via the reduction of Cu{sup 2+} ions by using an excess of hydrazine and PVP. The low sintering temperature (160 °C) in Ar atmosphere played an important role for the preparation of air-stable Cu patterns. The conductivity of a radio-frequency identification antenna made from nano-Cu ink was tested by a lamp, and its resistivity achieved 13.4 ± 0.4 μΩ cm. The Cu NPs were confirmed by means of X-ray powder diffraction and X-ray photoelectron spectra, and the Cu patterns were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. A mechanism for the high conductivity of the Cu pattern made from Cu NPs is proposed. - Highlights: • The synthesis of pure Cu is related to the reducing agent and capping agent. • The sintering under Ar atmosphere prevents Cu pattern's rapid oxidation. • The formation of the bulk Cu decreases the resistivity of the Cu pattern.

Surface Patterning Using Diazonium Ink Filled Nanopipette.

Science.gov (United States)

Zhou, Min; Yu, Yun; Blanchard, Pierre-Yves; Mirkin, Michael V

2015-11-03

Molecular grafting of diazonium is a widely employed surface modification technique. Local electrografting of this species is a promising approach to surface doping and related properties tailoring. The instability of diazonium cation complicates this process, so that this species was generated in situ in many reported studies. In this Article, we report the egress transfer of aryl diazonium cation across the liquid/liquid interface supported at the nanopipette tip that can be used for controlled delivery this species to the external aqueous phase for local substrate patterning. An aryl diazonium salt was prepared with weakly coordinating and lipophilic tetrakis(pentafluorophenyl)borate anion stable as a solid and soluble in low polarity media. The chemically stable solution of this salt in 1,2-dichloroethane can be used as "diazonium ink". The ink-filled nanopipette was employed as a tip in the scanning electrochemical microscope (SECM) for surface patterning with the spatial resolution controlled by the pipette orifice radius and a few nanometers film thickness. The submicrometer-size grafted spots produced on the HOPG surface were located and imaged with the atomic force microscope (AFM).

Formation of periodic and localized patterns in an oscillating granular layer.

Energy Technology Data Exchange (ETDEWEB)

Aranson, I.; Tsimring, L. S.; Materials Science Division; Bar Ilan Univ.; Univ. of California at San Diego

1998-02-01

A simple phenomenological model for pattern formation in a vertically vibrated layer of granular particles is proposed. This model exhibits a variety of stable cellular patterns including standing rolls and squares as well as localized excitations (oscillons and worms), similar to recent experimental observations (Umbanhowar et al., 1996). The model is an order parameter equation for the parametrically excited waves coupled to the mass conservation law. The structure and dynamics of the solutions resemble closely the properties of patterns observed in the experiments.

Factors controlling stable isotope composition of European precipitation

International Nuclear Information System (INIS)

Rozanski, K.; Sonntag, C.; Muennich, K.O.

1982-01-01

The seasonal and spatial variations of stable isotope ratios in present day European precipitation are simulated with a simple multibox model of the mean west-east horizontal transport of the atmospheric water vapour across the European continent. Isotope fractionation during the formation of precipitation leads to an increasing depletion of heavy isotopes in the residual air moisture as it moves towards the centre of the continent. This isotopic depletion is partly compensated, particularly in summer, by evapotranspiration, which is assumed to transfer soil water into the atmosphere without isotope fractionation. The model estimates are based on horizontal water vapour flux data, varying seasonally between 88 and 130 kg m -1 s -1 for the Atlantic coast region, and on the monthly precipitation, evapotranspiration and surface air temperature data available for various locations in Europe. Both continental and seasonal temperature effects observed in the stable isotope composition of European precipitation are fairly well reproduced by the model. The calculations show that the isotopic composition of local precipitation is primarily controlled by regional scale processes, i.e. by the water vapour transport patterns into the continent, and by the average precipitation-evapotranspiration history of the air masses precipitating at a given place. Local parameters such as the surface and/or cloud base temperature or the amount of precipitation modify the isotope ratios only slightly. Implications of the model predictions for the interpretation of stable isotope ratios in earlier periods as they are preserved in ice cores and in groundwater are also discussed. (Auth.)

Stable Boundary Layer Issues

OpenAIRE

Steeneveld, G.J.

2012-01-01

Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

Chemical fractionation of radionuclides and stable elements in aquatic plants of the Yenisei River.

Science.gov (United States)

Bolsunovsky, Alexander

2011-09-01

The Yenisei River is contaminated with artificial radionuclides released by one of the Russian nuclear plants. The aquatic plants growing in the radioactively contaminated parts of the river contain artificial radionuclides. The aim of the study was to investigate accumulation of artificial radionuclides and stable elements by submerged plants of the Yenisei River and estimate the strength of their binding to plant biomass by using a new sequential extraction scheme. The aquatic plants sampled were: Potamogeton lucens, Fontinalis antipyretica, and Batrachium kauffmanii. Gamma-spectrometric analysis of the samples of aquatic plants has revealed more than 20 radionuclides. We also investigated the chemical fractionation of radionuclides and stable elements in the biomass and rated radionuclides and stable elements based on their distribution in biomass. The greatest number of radionuclides strongly bound to biomass cell structures was found for Potamogeton lucens and the smallest for Batrachium kauffmanii. For Fontinalis antipyretica, the number of distribution patterns that were similar for both radioactive isotopes and their stable counterparts was greater than for the other studied species. The transuranic elements (239)Np and (241)Am were found in the intracellular fraction of the biomass, and this suggested their active accumulation by the plants.

Patterns of breast cancer mortality trends in Europe.

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Amaro, Joana; Severo, Milton; Vilela, Sofia; Fonseca, Sérgio; Fontes, Filipa; La Vecchia, Carlo; Lunet, Nuno

2013-06-01

To identify patterns of variation in breast cancer mortality in Europe (1980-2010), using a model-based approach. Mortality data were obtained from the World Health Organization database and mixed models were used to describe the time trends in the age-standardized mortality rates (ASMR). Model-based clustering was used to identify clusters of countries with homogeneous variation in ASMR. Three patterns were identified. Patterns 1 and 2 are characterized by stable or slightly increasing trends in ASMR in the first half of the period analysed, and a clear decline is observed thereafter; in pattern 1 the median of the ASMR is higher, and the highest rates were achieved sooner. Pattern 3 is characterised by a rapid increase in mortality until 1999, declining slowly thereafter. This study provides a general model for the description and interpretation of the variation in breast cancer mortality in Europe, based in three main patterns. Copyright © 2013 Elsevier Ltd. All rights reserved.

Golan Heights Groundwater Systems: Separation By REE+Y And Stable Isotopes

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Siebert, C.; Geyer, S.; Knoeller, K.; Roediger, T.; Weise, S.; Dulski, P.; Moeller, P.; Guttman, J.

2008-12-01

In a semi-arid to arid country like Israel, all freshwater resources are under (over-) utilization. Particularly, the Golan Heights rank as one of the most important extraction areas of groundwater of good quality and quantity. Additionally the mountain range feed to a high degree the most important freshwater reservoir of Israel, the Sea of Galilee. Hence, knowing the sources and characters of the Golan Heights groundwater systems is an instantaneous demand regarding sustainable management and protection. Within the "German-Israeli-Jordanian-Palestinian Joint Research Program for the Sustainable Utilisation of Aquifer Systems", hundreds of water samples were taken from all over the Jordan-Dead Sea rift-system to understand groundwater flow-systems and salinisation. For that purpose, each sample was analysed for major and minor ions, rare earth elements including yttrium (REY) and stable isotopes of water (d18O, d2H). The REY distribution in groundwater is established during infiltration by the first water-rock interaction and consequently reflects the leachable components of sediments and rocks of the recharge area. In well- developed flow-systems, REY are adsorbed onto pore surfaces are in equilibrium with the percolating groundwater, even if the lithology changes (e.g. inter-aquifer flow). Thus, groundwater sampled from wells and springs still show the REY distribution pattern established in the recharge area. Since high temperatures do not occur in Golan Heights, d2H and d18O are less controlled by water-rock interaction than by climatic and geomorphological factors at the time of replenishment. Applying the REY signature as a grouping criterion of groundwaters, d18O vs. d2H plots yield a new dimension in interpreting isotope data. The combined use of hydrochemical and isotopic methods enabled us to contain the areas of replenishment and the flow-paths of all investigated groundwater in the Golan Heights. Despite location, salinity or temperature of spring or

Wall-crossing between stable and co-stable ADHM data

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Ohkawa, Ryo

2018-06-01

We prove formula between Nekrasov partition functions defined from stable and co-stable ADHM data for the plane following method by Nakajima and Yoshioka (Kyoto J Math 51(2):263-335, 2011) based on the theory of wall-crossing formula developed by Mochizuki (Donaldson type invariants for algebraic surfaces: transition of moduli stacks, Lecture notes in mathematics, vol 1972, Springer, Berlin, 2009). This formula is similar to conjectures by Ito et al. [J High Energy Phys 2013(5):045, 2013, (4.1), (4.2)] for A1 singularity.

Rhythmic patterns in ancient shells: Can we reconstruct sub-annual cyclicity in trace element and stable isotope profiles from rudist bivalves?

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de Winter, N.; Sinnesael, M.; Vansteenberge, S.; Goderis, S.; Snoeck, C.; Van Malderen, S. J. M.; Vanhaecke, F. F.; Claeys, P.

2017-12-01

Well-preserved shells of Torreites rudists from the Late Campanian Saiwan Formation in Oman exhibit fine internal layering. These fine (±20 µm) laminae are rhythmically bundled (±400 µm) and subdivide the shells' larger scale annual lamination (±15 mm), suggesting the presence of several interfering cycles in shell growth rate. The aim of the present study is to determine the duration and chemical signature of these rhythmic variations in shell composition. To achieve this, a range of micro-analytical techniques is applied on cross sections through the shells. Firstly, microscopy-based layer counting and colorimetric analysis are carried out on thin sections of shell calcite. Secondly, X-Ray Fluorescence (XRF) and Fourier Transform InfraRed (FTIR) mapping of cross sections of the shells reveal chemical and structural differences between laminae in 2D. Thirdly, high-resolution XRF (25 µm) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS; 10 µm) trace element profiles are used to quantify variations in chemical composition between shell laminae. Fourthly, annual chronology is established based on micro-sampled stable carbon and oxygen stable isotope measurements (250 µm) along the growth axis of the shells. Finally, spectral analysis routines are applied to extract rhythmic patterns matched to the shell laminae from the structural, chemical and colorimetric data. Combining these methods allows for a full evaluation of the structural and chemical characteristics as well as the timing of sub-annual lamination in rudist shells. The results of this study shed light on the external factors that influenced growth rates in rudist bivalves. A better understanding of the timing of deposition of these laminae allows them to be used to improve age models of geochemical records in rudist shells. Characterization of small scale variations in shell composition will characterize the uncertainties contained within lower resolution proxy records from

Note: Using a Kösters prism to create a fringe pattern.

Science.gov (United States)

Capellmann, R F; Bewerunge, J; Platten, F; Egelhaaf, S U

2017-05-01

The interference of two crossed laser beams results in a standing wave. Such fringe patterns are exploited in different instruments such as interferometers or laser-Doppler anemometers. We create a fringe pattern in the sample plane of a microscope using a compact apparatus based on a Kösters prism. The fringe pattern is shown to be spatially and temporally very stable, covers a large area, and its spacing is easily tunable. In addition, we exploit it to impose a sinusoidal potential on colloidal particles.

Stable water isotope patterns in a climate change hotspot: the isotope hydrology framework of Corsica (western Mediterranean).

Science.gov (United States)

van Geldern, Robert; Kuhlemann, Joachim; Schiebel, Ralf; Taubald, Heinrich; Barth, Johannes A C

2014-06-01

The Mediterranean is regarded as a region of intense climate change. To better understand future climate change, this area has been the target of several palaeoclimate studies which also studied stable isotope proxies that are directly linked to the stable isotope composition of water, such as tree rings, tooth enamel or speleothems. For such work, it is also essential to establish an isotope hydrology framework of the region of interest. Surface waters from streams and lakes as well as groundwater from springs on the island of Corsica were sampled between 2003 and 2009 for their oxygen and hydrogen isotope compositions. Isotope values from lake waters were enriched in heavier isotopes and define a local evaporation line (LEL). On the other hand, stream and spring waters reflect the isotope composition of local precipitation in the catchment. The intersection of the LEL and the linear fit of the spring and stream waters reflect the mean isotope composition of the annual precipitation (δP) with values of-8.6(± 0.2) ‰ for δ(18)O and-58(± 2) ‰ for δ(2)H. This value is also a good indicator of the average isotope composition of the local groundwater in the island. Surface water samples reflect the altitude isotope effect with a value of-0.17(± 0.02) ‰ per 100 m elevation for oxygen isotopes. At Vizzavona Pass in central Corsica, water samples from two catchments within a lateral distance of only a few hundred metres showed unexpected but systematic differences in their stable isotope composition. At this specific location, the direction of exposure seems to be an important factor. The differences were likely caused by isotopic enrichment during recharge in warm weather conditions in south-exposed valley flanks compared to the opposite, north-exposed valley flanks.

An algebraic method for constructing stable and consistent autoregressive filters

International Nuclear Information System (INIS)

Harlim, John; Hong, Hoon; Robbins, Jacob L.

2015-01-01

In this paper, we introduce an algebraic method to construct stable and consistent univariate autoregressive (AR) models of low order for filtering and predicting nonlinear turbulent signals with memory depth. By stable, we refer to the classical stability condition for the AR model. By consistent, we refer to the classical consistency constraints of Adams–Bashforth methods of order-two. One attractive feature of this algebraic method is that the model parameters can be obtained without directly knowing any training data set as opposed to many standard, regression-based parameterization methods. It takes only long-time average statistics as inputs. The proposed method provides a discretization time step interval which guarantees the existence of stable and consistent AR model and simultaneously produces the parameters for the AR models. In our numerical examples with two chaotic time series with different characteristics of decaying time scales, we find that the proposed AR models produce significantly more accurate short-term predictive skill and comparable filtering skill relative to the linear regression-based AR models. These encouraging results are robust across wide ranges of discretization times, observation times, and observation noise variances. Finally, we also find that the proposed model produces an improved short-time prediction relative to the linear regression-based AR-models in forecasting a data set that characterizes the variability of the Madden–Julian Oscillation, a dominant tropical atmospheric wave pattern

Angina Pectoris (Stable Angina)

Science.gov (United States)

... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Angina Pectoris (Stable Angina) Updated:Aug 21,2017 You may have heard the term “angina pectoris” or “stable angina” in your doctor’s office, ...

Increased neutrophil expression of pattern recognition receptors during COPD exacerbations

NARCIS (Netherlands)

Pouwels, Simon D.; Van Geffen, Wouter H.; Jonker, Marnix R.; Kerstjens, Huib A. M.; Nawijn, Martijn C.; Heijink, Irene H.

Previously, we observed increased serum levels of damage-associated molecular patterns (DAMPs) during COPD exacerbations. Here, gene expression of DAMP receptors was measured in peripheral blood neutrophils of COPD patients during stable disease and severe acute exacerbation. The expression of

Stable reconstruction of Arctic sea level for the 1950-2010 period

OpenAIRE

Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

2016-01-01

Reconstruction of historical Arctic sea level is generally difficult due to the limited coverage and quality of both tide gauge and altimetry data in the area. Here a strategy to achieve a stable and plausible reconstruction of Arctic sea level from 1950 to today is presented. This work is based on the combination of tide gauge records and a new 20-year reprocessed satellite altimetry derived sea level pattern. Hence the study is limited to the area covered by satellite altimetry (68ºN and 82...

The Contribution of Proprioceptive Information to Postural Control in Elderly and Patients with Parkinson’s Disease with a History of Falls

Science.gov (United States)

Bekkers, Esther M. J.; Dockx, Kim; Heremans, Elke; Vercruysse, Sarah; Verschueren, Sabine M. P.; Mirelman, Anat; Nieuwboer, Alice

2014-01-01

Proprioceptive deficits negatively affect postural control but their precise contribution to postural instability in Parkinson’s disease (PD) is unclear. We investigated if proprioceptive manipulations differentially affect balance, measured by force plates, during quiet standing in 13 PD patients and 13 age-matched controls with a history of falls. Perceived limits of stability (LoS) were derived from the differences between maximal center of pressure (CoP) displacement in anterior–posterior (AP) and medio-lateral (ML) direction during a maximal leaning task. Task conditions comprised standing with eyes open (EO) and eyes closed (EC): (1) on a stable surface; (2) an unstable surface; and (3) with Achilles tendon vibration. CoP displacements were calculated as a percentage of their respective LoS. Perceived LoS did not differ between groups. PD patients showed greater ML CoP displacement than elderly fallers (EF) across all conditions (p = 0.043) and tended to have higher postural sway in relation to the LoS (p = 0.050). Both groups performed worse on an unstable surface and during tendon vibration compared to standing on a stable surface with EO and even more so with EC. Both PD and EF had more AP sway in all conditions with EC compared to EO (p postural control in fallers with and without PD. PD fallers showed higher ML sway after sensory manipulations, as a result of which these values approached their perceived LoS more closely than in EF. We conclude that despite a similar fall history, PD patients showed more ML instability than EF, irrespective of sensory manipulation, but had a similar reliance on ankle proprioception. Hence, we recommend that rehabilitation and fall prevention for PD should focus on motor rather than on sensory aspects. PMID:25505395

The contribution of proprioceptive information to postural control in elderly and patients with Parkinson's disease with a history of falls.

Science.gov (United States)

Bekkers, Esther M J; Dockx, Kim; Heremans, Elke; Vercruysse, Sarah; Verschueren, Sabine M P; Mirelman, Anat; Nieuwboer, Alice

2014-01-01

Proprioceptive deficits negatively affect postural control but their precise contribution to postural instability in Parkinson's disease (PD) is unclear. We investigated if proprioceptive manipulations differentially affect balance, measured by force plates, during quiet standing in 13 PD patients and 13 age-matched controls with a history of falls. Perceived limits of stability (LoS) were derived from the differences between maximal center of pressure (CoP) displacement in anterior-posterior (AP) and medio-lateral (ML) direction during a maximal leaning task. Task conditions comprised standing with eyes open (EO) and eyes closed (EC): (1) on a stable surface; (2) an unstable surface; and (3) with Achilles tendon vibration. CoP displacements were calculated as a percentage of their respective LoS. Perceived LoS did not differ between groups. PD patients showed greater ML CoP displacement than elderly fallers (EF) across all conditions (p = 0.043) and tended to have higher postural sway in relation to the LoS (p = 0.050). Both groups performed worse on an unstable surface and during tendon vibration compared to standing on a stable surface with EO and even more so with EC. Both PD and EF had more AP sway in all conditions with EC compared to EO (p postural control in fallers with and without PD. PD fallers showed higher ML sway after sensory manipulations, as a result of which these values approached their perceived LoS more closely than in EF. We conclude that despite a similar fall history, PD patients showed more ML instability than EF, irrespective of sensory manipulation, but had a similar reliance on ankle proprioception. Hence, we recommend that rehabilitation and fall prevention for PD should focus on motor rather than on sensory aspects.

Combinatorial Study of Surface Pattern Formation in Thin Block Copolymer Films

International Nuclear Information System (INIS)

Smith, Archie P.; Douglas, Jack F.; Meredith, J. Carson; Amis, Eric J.; Karim, Alamgir

2001-01-01

Surface pattern formation in diblock copolymer films is investigated as a function of film thickness h and molecular mass M . Smooth films are observed for certain h ranges centered about multiples of the lamellar thickness L 0 , and we attribute this effect to an increase in the surface chain density with h in the outer brushlike copolymer layer. We also observe apparently stable labyrinthine surface patterns for other h ranges, and the average size of these patterns is found to scale as λ∼L -2.5 0 . Hole and island patterns occur for h ranges between those of the labyrinthine patterns and the smooth regions, and their size similarly decreases with L 0 and M

Normal modified stable processes

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Shephard, N.

2002-01-01

Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process......This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...

Uses of stable isotopes

International Nuclear Information System (INIS)

Axente, Damian

1998-01-01

The most important fields of stable isotope use with examples are presented. These are: 1. Isotope dilution analysis: trace analysis, measurements of volumes and masses; 2. Stable isotopes as tracers: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic; 3. Isotope equilibrium effects: measurement of equilibrium effects, investigation of equilibrium conditions, mechanism of drug action, study of natural processes, water cycle, temperature measurements; 4. Stable isotope for advanced nuclear reactors: uranium nitride with 15 N as nuclear fuel, 157 Gd for reactor control. In spite of some difficulties of stable isotope use, particularly related to the analytical techniques, which are slow and expensive, the number of papers reporting on this subject is steadily growing as well as the number of scientific meetings organized by International Isotope Section and IAEA, Gordon Conferences, and regional meeting in Germany, France, etc. Stable isotope application development on large scale is determined by improving their production technologies as well as those of labeled compound and the analytical techniques. (author)

New DRIE-Patterned Electrets for Vibration Energy Harvesting

Directory of Open Access Journals (Sweden)

Chaillout J.-J.

2012-10-01

Full Text Available This paper is about a new manufacturing process aimed at developing stable SiO2/Si3N4 patterned electrets using a Deep Reactive Ion Etching (DRIE step for an application in electret-based Vibration Energy Harvesters (e-VEH. This process consists in forming continuous layers of SiO2/Si3N4 electrets in order to limit surface conduction phenomena and is a new way to see the problem of electret patterning. Experimental results prove that patterned electrets charged by a positive corona discharge show excellent stability with high surface charge densities that may reach 5mC/m2 on 1.1μm-thick layers, even with fine patterning and harsh temperature conditions (up to 250°C. This paves the way to new e-VEH designs and manufacturing processes.

Stable isotopes labelled compounds

International Nuclear Information System (INIS)

1982-09-01

The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

Stable Boundary Layer Issues

NARCIS (Netherlands)

Steeneveld, G.J.

2012-01-01

Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

Advances in single-molecule magnet surface patterning through microcontact printing.

Science.gov (United States)

Mannini, Matteo; Bonacchi, Daniele; Zobbi, Laura; Piras, Federica M; Speets, Emiel A; Caneschi, Andrea; Cornia, Andrea; Magnani, Agnese; Ravoo, Bart Jan; Reinhoudt, David N; Sessoli, Roberta; Gatteschi, Dante

2005-07-01

We present an implementation of strategies to deposit single-molecule magnets (SMMs) using microcontact printing microCP). We describe different approaches of microCP to print stripes of a sulfur-functionalized dodecamanganese (III, IV) cluster on gold surfaces. Comparison by atomic force microscopy profile analysis of the patterned structures confirms the formation of a chemically stable single layer of SMMs. Images based on chemical contrast, obtained by time-of-flight secondary ion mass spectrometry, confirm the patterned structure.

Trophic relationships in a tropical stream food web assessed by stable isotope analysis

OpenAIRE

Coat, Sophie; Monti, Dominique; Bouchon, Claude; Lepoint, Gilles

2009-01-01

1. Stable isotope analysis, coupled with dietary data from the literature, was used to investigate trophic patterns of freshwater fauna in a tropical stream food web (Guadeloupe, French West Indies). 2. Primary producers (biofilm, algae and plant detritus of terrestrial origin) showed distinct delta C-13 signatures, which allowed for a powerful discrimination of carbon sources. Both autochthonous (C-13-enriched signatures) and allochthonous (C-13-depleted signatures) resources enter the food ...

One-pot radioiodination of aryl amines via stable diazonium salts: preparation of 125I-imaging agents

OpenAIRE

Sloan, Nikki L.; Luthra, Sajinder K.; McRobbie, Graeme; Pimlott, Sally L.; Sutherland, Andrew

2017-01-01

An operationally simple, one-pot, two-step tandem procedure that allows the incorporation of radioactive iodine into aryl amines via stable diazonium salts is described. The mild conditions are tolerant of various functional groups and substitution patterns, allowing late-stage, rapid access to a wide range of 125I-labelled aryl compounds and SPECT radiotracers.

Patterns of poverty exposure and children’s trajectories of externalizing and internalizing behaviors

OpenAIRE

Comeau, Jinette; Boyle, Michael H.

2017-01-01

Using data from the Child Supplement of the National Longitudinal Survey of Youth, we compare trajectories of externalizing and internalizing behaviors among children exposed to five patterns of poverty from birth to age 14: always or never poor – stable patterns; a single transition into or out of poverty, or repeated fluctuations in and out of poverty – changing patterns. We also examine how low maternal education and single parenthood interact with these poverty exposures to compound their...

Structure of acid-stable carmine.

Science.gov (United States)

Sugimoto, Naoki; Kawasaki, Yoko; Sato, Kyoko; Aoki, Hiromitsu; Ichi, Takahito; Koda, Takatoshi; Yamazaki, Takeshi; Maitani, Tamio

2002-02-01

Acid-stable carmine has recently been distributed in the U.S. market because of its good acid stability, but it is not permitted in Japan. We analyzed and determined the structure of the major pigment in acid-stable carmine, in order to establish an analytical method for it. Carminic acid was transformed into a different type of pigment, named acid-stable carmine, through amination when heated in ammonia solution. The features of the structure were clarified using a model compound, purpurin, in which the orientation of hydroxyl groups on the A ring of the anthraquinone skeleton is the same as that of carminic acid. By spectroscopic means and the synthesis of acid-stable carmine and purpurin derivatives, the structure of the major pigment in acid-stable carmine was established as 4-aminocarminic acid, a novel compound.

Stable nitrogen isotope analysis of dentine serial sections elucidate sex differences in weaning patterns of wild chimpanzees (Pan troglodytes).

Science.gov (United States)

Fahy, Geraldine E; Richards, Michael P; Fuller, Benjamin T; Deschner, Tobias; Hublin, Jean-Jacques; Boesch, Christophe

2014-04-01

Offspring provisioning is one of the most energetically demanding aspects of reproduction for female mammals. Variation in lactation length and weaning strategies between chimpanzees (Pan troglodytes), our closest living relative, and modern human societies have been reported. When and why these changes occurred is frequently debated. Our study used stable nitrogen isotope data of tooth root dentine from wild Western chimpanzees (Pan troglodytes verus) in Taï National Park, Côte d'Ivoire, to quantify weaning in these chimpanzees and explore if infant sex plays a role in maternal investment. We analyzed serial sections of deciduous lateral incisor root dentine from four Taï chimpanzees to establish the δ(15) N signal of nursing infants; we then analyzed serial sections of first permanent mandibular molar root dentine from 12 Taï chimpanzees to provide quantitative δ(15) N data on weaning in this population. Up to 2 years of age both sexes exhibited dentine δ(15) N values ≈2-3‰ higher than adult female Taï chimpanzees, consistent with a nursing signal. Thereafter a steady decrease in δ(15) N values consistent with the onset, and progression, of weaning, was visible. Sex differences were also evident, where male δ(15) N values decreased at a significantly slower rate compared to females. Confirmation of sex differences in maternal investment among Taï chimpanzees, demonstrates the viability of using isotope analysis to investigate weaning in non-human primates. Additionally, assuming that behaviors observed in the Taï chimpanzees are illustrative of the ancestral pattern, our results provide a platform to enable the trajectory of weaning in human evolution to be further explored. Copyright © 2013 Wiley Periodicals, Inc.

Outcomes of stable and unstable patterns of subjective cognitive decline – results from the Leipzig Longitudinal Study of the Aged (LEILA75+

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Susanne Roehr

2016-11-01

Full Text Available Abstract Background Subjective cognitive decline (SCD, i.e., the self-perceived feeling of worsening cognitive function, may be the first notable syndrome of preclinical Alzheimer’s disease and other dementias. However, not all individuals with SCD progress. Stability of SCD, i.e., repeated reports of SCD, could contribute to identify individuals at risk, as stable SCD may more likely reflect the continuous neurodegenerative process of Alzheimer’s and other dementias. Methods Cox regression analyses were used to assess the association between stability of SCD and progression to MCI and dementia in data derived from the population-based Leipzig Longitudinal Study of the Aged (LEILA75+. Results Of 453 cognitively unimpaired individuals with a mean age of 80.5 years (SD = 4.2, 139 (30.7 % reported SCD at baseline. Over the study period (M = 4.8 years, SD = 2.2, 84 (18.5 % individuals had stable SCD, 195 (43.1 % unstable SCD and 174 (38.4 % never reported SCD. Stable SCD was associated with increased risk of progression to MCI and dementia (unadjusted HR = 1.8, 95 % CI = 1.2–2.6; p < .01, whereas unstable SCD yielded a decreased progression risk (unadjusted HR = 0.5, 95 % CI = 0.4–0.7; p < .001 compared to no SCD. When adjusted for baseline cognitive functioning, progression risk in individuals with stable SCD was significantly increased in comparison to individuals with unstable SCD, but not compared to individuals without SCD. Conclusions Our results, though preliminary, suggest that stable SCD, i.e., repeated reports of SCD, may yield an increased risk of progression to MCI and dementia compared to unstable SCD. Baseline cognitive scores, though within a normal range, seem to be a driver of progression in stable SCD. Future research is warranted to investigate whether stability could hold as a SCD research feature.

Applications of stable isotopes

International Nuclear Information System (INIS)

Letolle, R.; Mariotti, A.; Bariac, T.

1991-06-01

This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

DNA Methylation and Methylation Polymorphism in Genetically Stable In vitro Regenerates of Jatropha curcas L. Using Methylation-Sensitive AFLP Markers.

Science.gov (United States)

Rathore, Mangal S; Jha, Bhavanath

2016-03-01

The present investigation aimed to evaluate the degree and pattern of DNA methylation using methylation-sensitive AFLP (MS-AFLP) markers in genetically stable in vitro regenerates of Jatropha curcas L.. The genetically stable in vitro regenerates were raised through direct organogenesis via enhanced axillary shoot bud proliferation (Protocol-1) and in vitro-derived leaf regeneration (Protocol-2). Ten selective combinations of MS-AFLP primers produced 462 and 477 MS-AFLP bands in Protocol-1 (P-1) and Protocol-2 (P-2) regenerates, respectively. In P-1 regenerates, 15.8-31.17 % DNA was found methylated with an average of 25.24 %. In P-2 regenerates, 15.93-32.7 % DNA was found methylated with an average of 24.11 %. Using MS-AFLP in P-1 and P-2 regenerates, 11.52-25.53 % and 13.33-25.47 % polymorphism in methylated DNA was reported, respectively. Compared to the mother plant, P-1 regenerates showed hyper-methylation while P-2 showed hypo-methylation. The results clearly indicated alternation in degree and pattern of DNA methylation; hence, epigenetic instability in the genetically stable in vitro regenerates of J. curcas, developed so far using two different regeneration systems and explants of two different origins. The homologous nucleotide fragments in genomes of P-1 and P-2 regenerates showing methylation re-patterning might be involved in immediate adaptive responses and developmental processes through differential regulation of transcriptome under in vitro conditions.

Non-Gaussian distributions of melodic intervals in music: The Lévy-stable approximation

Science.gov (United States)

Niklasson, Gunnar A.; Niklasson, Maria H.

2015-11-01

The analysis of structural patterns in music is of interest in order to increase our fundamental understanding of music, as well as for devising algorithms for computer-generated music, so called algorithmic composition. Musical melodies can be analyzed in terms of a “music walk” between the pitches of successive tones in a notescript, in analogy with the “random walk” model commonly used in physics. We find that the distribution of melodic intervals between tones can be approximated with a Lévy-stable distribution. Since music also exibits self-affine scaling, we propose that the “music walk” should be modelled as a Lévy motion. We find that the Lévy motion model captures basic structural patterns in classical as well as in folk music.

Longitudinal analysis of dietary patterns in Chinese adults from 1991 to 2009.

Science.gov (United States)

Batis, Carolina; Sotres-Alvarez, Daniela; Gordon-Larsen, Penny; Mendez, Michelle A; Adair, Linda; Popkin, Barry

2014-04-28

In the present study, we aimed to identify the changes or stability in the structure of dietary patterns and tracking, trends and factors related to the adherence to these dietary patterns in China from 1991 to 2009. We analysed dietary data collected during seven waves of the China Health and Nutrition Survey and included 9253 adults with complete dietary data for three or more waves. Dietary intake assessment was carried out over a 3 d period with 24 h recalls and a household food inventory. Using factor analysis in each wave, we found that the structure of the two dietary patterns identified remained stable over the studied period. The traditional southern dietary pattern was characterised by high intakes of rice, fresh leafy vegetables, low-fat red meat, pork, organ meats, poultry and fish/seafood and low intakes of wheat flour and maize/coarse grains and the modern high-wheat dietary pattern was characterised by high intakes of wheat buns/breads, cakes/cookies/pastries, deep-fried wheat, nuts/seeds, starchy root/tuber products, fruits, eggs/egg products, soya milk, animal-based milk and instant noodles/frozen dumplings. Temporal tracking (maintenance of a relative position over time) was higher for the traditional southern dietary pattern, whereas adherence to the modern high-wheat dietary pattern had an upward trend over time. Higher income, education and urbanicity levels were positively associated with both the dietary patterns, but the association became weaker in the later years. These results suggest that even in the context of rapid economic changes in China, the way people chose to combine their foods remained relatively stable. However, the increasing popularity of the modern high-wheat dietary pattern, a pattern associated with several energy-dense foods, is a cause of concern.

Unintentional Interpersonal Synchronization Represented as a Reciprocal Visuo-Postural Feedback System: A Multivariate Autoregressive Modeling Approach.

Directory of Open Access Journals (Sweden)

Shuntaro Okazaki

Full Text Available People's behaviors synchronize. It is difficult, however, to determine whether synchronized behaviors occur in a mutual direction--two individuals influencing one another--or in one direction--one individual leading the other, and what the underlying mechanism for synchronization is. To answer these questions, we hypothesized a non-leader-follower postural sway synchronization, caused by a reciprocal visuo-postural feedback system operating on pairs of individuals, and tested that hypothesis both experimentally and via simulation. In the behavioral experiment, 22 participant pairs stood face to face either 20 or 70 cm away from each other wearing glasses with or without vision blocking lenses. The existence and direction of visual information exchanged between pairs of participants were systematically manipulated. The time series data for the postural sway of these pairs were recorded and analyzed with cross correlation and causality. Results of cross correlation showed that postural sway of paired participants was synchronized, with a shorter time lag when participant pairs could see one another's head motion than when one of the participants was blindfolded. In addition, there was less of a time lag in the observed synchronization when the distance between participant pairs was smaller. As for the causality analysis, noise contribution ratio (NCR, the measure of influence using a multivariate autoregressive model, was also computed to identify the degree to which one's postural sway is explained by that of the other's and how visual information (sighted vs. blindfolded interacts with paired participants' postural sway. It was found that for synchronization to take place, it is crucial that paired participants be sighted and exert equal influence on one another by simultaneously exchanging visual information. Furthermore, a simulation for the proposed system with a wider range of visual input showed a pattern of results similar to the

Template-assisted electrohydrodynamic atomization of polycaprolactone for orthopedic patterning applications

Energy Technology Data Exchange (ETDEWEB)

Nithyanandan, Anouska; Mahalingam, Suntharavathanan; Huang, Jie [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom); Rehman, Sarrawat; Draper, Edward [JRI Orthopaedics Ltd., 18 Churchill Way, 35A Business Park, Chapeltown, Sheffield S35 2PY (United Kingdom); Edirisinghe, Mohan, E-mail: m.edirisinghe@ucl.ac.uk [Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

2013-12-01

This paper presents the development of the novel deposition of biodegradable polycaprolactone (PCL) polymer patterns on a metallic substrate using a jet spraying technique, template-assisted electrohydrodynamic atomization (TAEA), at ambient temperature. The structure of patterns was controlled by systematically varying the polymer concentration (2–15 wt.%) and the flow rate (1–25 μl min{sup −1}). Polymer deposition was carried out in the stable cone-jet mode to precisely control the surface structure and morphology. The patterns were studied by optical microscopy, scanning electron microscopy and profilometry, and a high degree of control over the pattern geometry and thickness was achieved by varying the spraying time. The hardness and the effective elastic modulus of the polymer patterns were estimated using nanoindentation. The effect of load, loading rate and the holding time on the hardness and effective elastic modulus was derived. Optimal results were obtained with 5 wt.% PCL in DMAC solution sprayed within the stable cone-jet mode operating window at a flow rate of 15 μl min{sup −1} for 300 s at 11.1 kV with a working distance of 60 mm. Hexagonal patterns were well-defined and repeatable with thickness of ∼ 34 μm. The hardness is 1.6 MPa at a loading rate of 0.1 μN/s and nearly halved when the load rate was increased to 1 μN/s. The effective elastic modulus of ∼ 12 MPa is obtained for a load rate of 0.1 μN/s. - Highlights: • For the first time, hexagonal PCL patterns have been applied onto Ti using TAEA. • TAEA produces controlled polymer topographies at ambient temperature. • PCL concentration (2–15 wt.%) and flow rate (1–25 μl min{sup −1}) were systematically varied. • Pattern hardness was 1.6 MPa and effective modulus was 12 MPa for load rate 0.1 μN/s. • Mean pattern thickness was ∼ 34 μm, increasing with flow rate and PCL concentration.

Contribution of Head Position, Standing Surface, and Vision to Postural Control in Community-Dwelling Older Adults.

Science.gov (United States)

Pociask, Fredrick D; DiZazzo-Miller, Rosanne; Goldberg, Allon; Adamo, Diane E

2016-01-01

Postural control requires the integration of sensorimotor information to maintain balance and to properly position and orient the body in response to external stimuli. Age-related declines in peripheral and central sensory and motor function contribute to postural instability and falls. This study investigated the contribution of head position, standing surface, and vision on postural sway in 26 community-dwelling older adults. Participants were asked to maintain a stable posture under conditions that varied standing surface, head position, and the availability of visual information. Significant main and interaction effects were found for all three factors. Findings from this study suggest that postural sway responses require the integration of available sources of sensory information. These results have important implications for fall risks in older adults and suggest that when standing with the head extended and eyes closed, older adults may place themselves at risk for postural disequilibrium and loss of balance. Copyright © 2016 by the American Occupational Therapy Association, Inc.

Stable three-dimensional solitons in attractive Bose-Einstein condensates loaded in an optical lattice

International Nuclear Information System (INIS)

Mihalache, D.; Mazilu, D.; Lederer, F.; Malomed, B.A.; Crasovan, L.-C.; Kartashov, Y.V.; Torner, L.

2005-01-01

The existence and stability of solitons in Bose-Einstein condensates with attractive interatomic interactions, described by the Gross-Pitaevskii equation with a three-dimensional (3D) periodic potential, are investigated in a systematic form. We find a one-parameter family of stable 3D solitons in a certain interval of values of their norm, provided that the strength of the potential exceeds a threshold value. The minimum number of 7 Li atoms in the stable solitons is 60, and the energy of the soliton at the stability threshold is ≅6 recoil energies in the lattice. The respective energy versus norm diagram features two cuspidal points, resulting in a typical swallowtail pattern, which is a generic feature of 3D solitons supported by quasi-two-dimensional or fully dimensional lattice potentials

Stable isotopes of carbon and nitrogen as markers of dietary variation among sociocultural subgroups of Inuit in Greenland

DEFF Research Database (Denmark)

Bjerregaard, Peter; Larsen, Christina V L; Dahl-Petersen, Inger K

2017-01-01

OBJECTIVES: We assessed the use of stable isotopes of carbon and nitrogen as biomarkers for traditional versus store-bought food among the Inuit. Furthermore, we compared the isotope patterns among sociocultural population groups. METHODS: As a part of a country-wide health survey in Greenland...... food in the diet was estimated at 21% from the mean δ(13) C value, 25% from the mean δ(15) N value, and 23% from the FFQ. CONCLUSION: Nail samples for analysis of stable isotopes of carbon and nitrogen were convenient to collect during a large population health survey among the Inuit. Isotope...

Vitamin D deficiency intensifies deterioration of risk factors, such as male sex and absence of vision, leading to increased postural body sway.

Science.gov (United States)

Krause, Matthias; Anschütz, Wilma; Vettorazzi, Eik; Breer, Stefan; Amling, Michael; Barvencik, Florian

2014-01-01

Due to inconsistent findings, the influence of vitamin D on postural body sway (PBS) is currently under debate. This study evaluated the impact of vitamin D on PBS with regards to different foot positions and eye opening states in community-dwelling older individuals. In a cross-sectional study, we assessed PBS in 342 older individuals (264 females [average age (± SD): 68.3 ± 9.0 years], 78 males [65.7 ± 9.6 years]). A detailed medical history and vitamin D level were obtained for each individual. Fall risk was evaluated using the New York-Presbyterian Fall Risk Assessment Tool (NY PFRA). PBS parameters (area, distance, velocity, frequency) were evaluated on a pressure plate with feet in closed stance (CS) or hip-width stance (HWS), open eyes and closed eyes. Statistical analysis included logarithmic mixed models for repeated measures with the MIXED model procedure to test the influence of vitamin D (categorized in 30 μg/l), foot position, eye opening state, age, sex and frequency of physical activity on PBS. Vitamin D was not an independent risk factor for falls experienced in the last 12 months. Nonetheless, PBS was higher in patients with vitamin D deficiency (risk factors for increased PBS like male sex and absence of vision are additionally compromised by vitamin D deficiency. Copyright © 2013 Elsevier B.V. All rights reserved.

Using the stable carbon and nitrogen isotope compositions of vervet monkeys (Chlorocebus pygerythrus to examine questions in ethnoprimatology.

Directory of Open Access Journals (Sweden)

James E Loudon

Full Text Available This study seeks to understand how humans impact the dietary patterns of eight free-ranging vervet monkey (Chlorocebus pygerythrus groups in South Africa using stable isotope analysis. Vervets are omnivores that exploit a wide range of habitats including those that have been anthropogenically-disturbed. As humans encroach upon nonhuman primate landscapes, human-nonhuman primate interconnections become increasingly common, which has led to the rise of the field of ethnoprimatology. To date, many ethnoprimatological studies have examined human-nonhuman primate associations largely in qualitative terms. By using stable carbon (δ13C and nitrogen (δ15N isotope analysis, we use quantitative data to understand the degree to which humans impact vervet monkey dietary patterns. Based on initial behavioral observations we placed the eight groups into three categories of anthropogenic disturbance (low, mid, and high. Using δ13C and δ15N values we estimated the degree to which each group and each anthropogenically-disturbed category was consuming C4 plants (primarily sugar cane, corn, or processed foods incorporating these crops. δ13C values were significantly different between groups and categories of anthropogenic-disturbance. δ15N values were significantly different at the group level. The two vervet groups with the highest consumption of C4 plants inhabited small nature reserves, appeared to interact with humans only sporadically, and were initially placed in the mid level of anthropogenic-disturbance. However, further behavioral observations revealed that the high δ13C values exhibited by these groups were linked to previously unseen raiding of C4 crops. By revealing these cryptic feeding patterns, this study illustrates the utility of stable isotopes analysis for some ethnoprimatological questions.

Population Games, Stable Games, and Passivity

Directory of Open Access Journals (Sweden)

Michael J. Fox

2013-10-01

Full Text Available The class of “stable games”, introduced by Hofbauer and Sandholm in 2009, has the attractive property of admitting global convergence to equilibria under many evolutionary dynamics. We show that stable games can be identified as a special case of the feedback-system-theoretic notion of a “passive” dynamical system. Motivated by this observation, we develop a notion of passivity for evolutionary dynamics that complements the definition of the class of stable games. Since interconnections of passive dynamical systems exhibit stable behavior, we can make conclusions about passive evolutionary dynamics coupled with stable games. We show how established evolutionary dynamics qualify as passive dynamical systems. Moreover, we exploit the flexibility of the definition of passive dynamical systems to analyze generalizations of stable games and evolutionary dynamics that include forecasting heuristics as well as certain games with memory.

Unique dietary patterns and chronic disease risk profiles of adult men: the Framingham nutrition studies.

Science.gov (United States)

Millen, Barbara E; Quatromoni, Paula A; Pencina, Michael; Kimokoti, Ruth; Nam, Byung-H O; Cobain, Sonia; Kozak, Waldemar; Appugliese, Danielle P; Ordovas, Jose; D'Agostino, Ralph B

2005-11-01

To identify the dietary patterns of adult men and examine their relationships with nutrient intake and chronic disease risk over long-term follow-up. Baseline 145-item food frequency questionnaires from 1,666 Framingham Offspring-Spouse cohort men were used to identify comprehensive dietary patterns. Independent 3-day dietary records at baseline and 8 years later provided estimates of subjects' nutrient intake by dietary pattern. Chronic disease risk factor status was compared at baseline and 16-year follow-up across all male dietary patterns. Cluster analysis was applied to food frequency data to identify non-overlapping male dietary patterns. Analysis of covariance and logistic regression were used to compare nutrient intake, summary nutritional risk scores, and chronic disease risk status at baseline and follow-up by male dietary pattern. Five distinct and comprehensive dietary patterns of Framingham Offspring-Spouse men were identified and ordered according to overall nutritional risk: Transition to Heart Healthy, Higher Starch, Average Male, Lower Variety, and Empty Calories. Nutritional risk was high and varied by dietary pattern; key nutrient contrasts were stable over 8-year follow-up. Chronic disease risk also varied by dietary pattern and specific subgroup differences persisted over 16 years, notably rates of overweight/obesity and smoking. Quantitative cluster analysis applied to food frequency questionnaire data identified five distinct, comprehensive, and stable dietary patterns of adult Framingham Offspring-Spouse cohort men. The close associations between the dietary patterns, nutritional risk, and chronic disease profiles of men emphasize the importance of targeted preventive nutrition interventions to promote health in the male population.

A one-pot radioiodination of aryl amines via stable diazonium salts: preparation of 125I-imaging agents.

Science.gov (United States)

Sloan, Nikki L; Luthra, Sajinder K; McRobbie, Graeme; Pimlott, Sally L; Sutherland, Andrew

2017-10-05

An operationally simple, one-pot, two-step tandem procedure that allows the incorporation of radioactive iodine into aryl amines via stable diazonium salts is described. The mild conditions are tolerant of various functional groups and substitution patterns, allowing late-stage, rapid access to a wide range of 125 I-labelled aryl compounds and SPECT radiotracers.

Determining origin in a migratory marine vertebrate: a novel method to integrate stable isotopes and satellite tracking

Science.gov (United States)

Vander Zanden, Hannah B.; Tucker, Anton D.; Hart, Kristen M.; Lamont, Margaret M.; Fujisaki, Ikuko; Addison, David S.; Mansfield, Katherine L.; Phillips, Katrina F.; Wunder, Michael B.; Bowen, Gabriel J.; Pajuelo, Mariela; Bolten, Alan B.; Bjorndal, Karen A.

2015-01-01

Stable isotope analysis is a useful tool to track animal movements in both terrestrial and marine environments. These intrinsic markers are assimilated through the diet and may exhibit spatial gradients as a result of biogeochemical processes at the base of the food web. In the marine environment, maps to predict the spatial distribution of stable isotopes are limited, and thus determining geographic origin has been reliant upon integrating satellite telemetry and stable isotope data. Migratory sea turtles regularly move between foraging and reproductive areas. Whereas most nesting populations can be easily accessed and regularly monitored, little is known about the demographic trends in foraging populations. The purpose of the present study was to examine migration patterns of loggerhead nesting aggregations in the Gulf of Mexico (GoM), where sea turtles have been historically understudied. Two methods of geographic assignment using stable isotope values in known-origin samples from satellite telemetry were compared: 1) a nominal approach through discriminant analysis and 2) a novel continuous-surface approach using bivariate carbon and nitrogen isoscapes (isotopic landscapes) developed for this study. Tissue samples for stable isotope analysis were obtained from 60 satellite-tracked individuals at five nesting beaches within the GoM. Both methodological approaches for assignment resulted in high accuracy of foraging area determination, though each has advantages and disadvantages. The nominal approach is more appropriate when defined boundaries are necessary, but up to 42% of the individuals could not be considered in this approach. All individuals can be included in the continuous-surface approach, and individual results can be aggregated to identify geographic hotspots of foraging area use, though the accuracy rate was lower than nominal assignment. The methodological validation provides a foundation for future sea turtle studies in the region to inexpensively

Cognition-emotion interactions: patterns of change and implications for math problem solving

Science.gov (United States)

Trezise, Kelly; Reeve, Robert A.

2014-01-01

Surprisingly little is known about whether relationships between cognitive and emotional states remain stable or change over time, or how different patterns of stability and/or change in the relationships affect problem solving abilities. Nevertheless, cross-sectional studies show that anxiety/worry may reduce working memory (WM) resources, and the ability to minimize the effects anxiety/worry is higher in individuals with greater WM capacity. To investigate the patterns of stability and/or change in cognition-emotion relations over time and their implications for problem solving, 126 14-year-olds’ algebraic WM and worry levels were assessed twice in a single day before completing an algebraic math problem solving test. We used latent transition analysis to identify stability/change in cognition-emotion relations, which yielded a six subgroup solution. Subgroups varied in WM capacity, worry, and stability/change relationships. Among the subgroups, we identified a high WM/low worry subgroup that remained stable over time and a high WM/high worry, and a moderate WM/low worry subgroup that changed to low WM subgroups over time. Patterns of stability/change in subgroup membership predicted algebraic test results. The stable high WM/low worry subgroup performed best and the low WM capacity-high worry “unstable across time” subgroup performed worst. The findings highlight the importance of assessing variations in cognition-emotion relationships over time (rather than assessing cognition or emotion states alone) to account for differences in problem solving abilities. PMID:25132830

Cognition-emotion interactions: Patterns of change and implications for math problem solving

Directory of Open Access Journals (Sweden)

Kelly eTrezise

2014-07-01

Full Text Available Surprisingly little is known about whether relationships between cognitive and emotional states remain stable or change over time, or how different patterns of stability and/or change in the relationships affect problem solving abilities. Nevertheless, cross-sectional studies show that anxiety/worry may reduce working memory resources, and the ability to minimize the effects anxiety/worry is higher in individuals with greater WM capacity. To investigate the patterns of stability and/or change in cognition-emotion relations over time and their implications for problem solving, 126 14-year-olds’ algebraic WM and worry levels were assessed twice in a single day before completing an algebraic math problem solving test. We used latent transition analysis to identify stability/change in cognition-emotion relations, which yielded a six subgroup solution. Subgroups varied in WM capacity, worry, and stability/change relationships. Among the subgroups, we identified a high WM/low worry subgroup that remained stable over time and a high WM/high worry, and a moderate WM/low worry subgroup that changed to low WM subgroups over time. Patterns of stability/change in subgroup membership predicted algebraic test results. The stable high WM/low worry subgroup performed best and the low WM capacity-high worry unstable across time subgroup performed worst. The findings highlight the importance of assessing variations in cognition-emotion relationships over time (rather than assessing cognition or emotion states alone to account for differences in problem solving abilities.

Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system.

Science.gov (United States)

Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng

2015-12-21

We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices.

Patterns and potential drivers of dramatic changes in Tibetan lakes, 1972-2010.

Science.gov (United States)

Li, Yingkui; Liao, Jingjuan; Guo, Huadong; Liu, Zewen; Shen, Guozhuang

2014-01-01

Most glaciers in the Himalayas and the Tibetan Plateau are retreating, and glacier melt has been emphasized as the dominant driver for recent lake expansions on the Tibetan Plateau. By investigating detailed changes in lake extents and levels across the Tibetan Plateau from Landsat/ICESat data, we found a pattern of dramatic lake changes from 1970 to 2010 (especially after 2000) with a southwest-northeast transition from shrinking, to stable, to rapidly expanding. This pattern is in distinct contrast to the spatial characteristics of glacier retreat, suggesting limited influence of glacier melt on lake dynamics. The plateau-wide pattern of lake change is related to precipitation variation and consistent with the pattern of permafrost degradation induced by rising temperature. More than 79% of lakes we observed on the central-northern plateau (with continuous permafrost) are rapidly expanding, even without glacial contributions, while lakes fed by retreating glaciers in southern regions (with isolated permafrost) are relatively stable or shrinking. Our study shows the limited role of glacier melt and highlights the potentially important contribution of permafrost degradation in predicting future water availability in this region, where understanding these processes is of critical importance to drinking water, agriculture, and hydropower supply of densely populated areas in South and East Asia.

A mathematical basis for plant patterning derived from physico-chemical phenomena.

Science.gov (United States)

Beleyur, Thejasvi; Abdul Kareem, Valiya Kadavu; Shaji, Anil; Prasad, Kalika

2013-04-01

The position of leaves and flowers along the stem axis generates a specific pattern, known as phyllotaxis. A growing body of evidence emerging from recent computational modeling and experimental studies suggests that regulators controlling phyllotaxis are chemical, e.g. the plant growth hormone auxin and its dynamic accumulation pattern by polar auxin transport, and physical, e.g. mechanical properties of the cell. Here we present comprehensive views on how chemical and physical properties of cells regulate the pattern of leaf initiation. We further compare different computational modeling studies to understand their scope in reproducing the observed patterns. Despite a plethora of experimental studies on phyllotaxis, understanding of molecular mechanisms of pattern initiation in plants remains fragmentary. Live imaging of growth dynamics and physicochemical properties at the shoot apex of mutants displaying stable changes from one pattern to another should provide mechanistic insights into organ initiation patterns. Copyright © 2013 WILEY Periodicals, Inc.

400 Years of summer hydroclimate from stable isotopes in Iberian trees

Science.gov (United States)

Andreu-Hayles, Laia; Ummenhofer, Caroline C.; Barriendos, Mariano; Schleser, Gerhard H.; Helle, Gerhard; Leuenberger, Markus; Gutiérrez, Emilia; Cook, Edward R.

2017-07-01

Tree rings are natural archives that annually record distinct types of past climate variability depending on the parameters measured. Here, we use ring-width and stable isotopes in cellulose of trees from the northwestern Iberian Peninsula (IP) to understand regional summer hydroclimate over the last 400 years and the associated atmospheric patterns. Correlations between tree rings and climate data demonstrate that isotope signatures in the targeted Iberian pine forests are very sensitive to water availability during the summer period, and are mainly controlled by stomatal conductance. Non-linear methods based on extreme events analysis allow for capturing distinct seasonal climatic variability recorded by tree-ring parameters and asymmetric signals of the associated atmospheric features. Moreover, years with extreme high (low) values in the tree-ring records were characterised by coherent large-scale atmospheric circulation patterns with reduced (enhanced) moisture transport onto the northwestern IP. These analyses of extremes revealed that high/low proxy values do not necessarily correspond to mirror images in the atmospheric anomaly patterns, suggesting different drivers of these patterns and the corresponding signature recorded in the proxies. Regional hydroclimate features across the broader IP and western Europe during extreme wet/dry summers detected by the northwestern IP trees compare favourably to independent multicentury sea level pressure and drought reconstructions for Europe. Historical records also validate our findings that attribute non-linear moisture signals recorded by extreme tree-ring values to distinct large-scale atmospheric patterns and allow for 400-year reconstructions of the frequency of occurrence of extreme conditions in late spring and summer hydroclimate.

Stable particles

International Nuclear Information System (INIS)

Samios, N.P.

1993-01-01

I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

Selective wetting-induced micro-electrode patterning for flexible micro-supercapacitors.

Science.gov (United States)

Kim, Sung-Kon; Koo, Hyung-Jun; Lee, Aeri; Braun, Paul V

2014-08-13

Selective wetting-induced micro-electrode patterning is used to fabricate flexible micro-supercapacitors (mSCs). The resulting mSCs exhibit high performance, mechanical stability, stable cycle life, and hold great promise for facile integration into flexible devices requiring on-chip energy storage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of horse stable environment on human airways

Directory of Open Access Journals (Sweden)

Pringle John

2009-05-01

Full Text Available Abstract Background Many people spend considerable amount of time each day in equine stable environments either as employees in the care and training of horses or in leisure activity. However, there are few studies available on how the stable environment affects human airways. This study examined in one horse stable qualitative differences in indoor air during winter and late summer conditions and assessed whether air quality was associated with clinically detectable respiratory signs or alterations to selected biomarkers of inflammation and lung function in stable personnel. Methods The horse stable environment and stable-workers (n = 13 in one stable were investigated three times; first in the winter, second in the interjacent late summer and the third time in the following winter stabling period. The stable measurements included levels of ammonia, hydrogen sulphide, total and respirable dust, airborne horse allergen, microorganisms, endotoxin and glucan. The stable-workers completed a questionnaire on respiratory symptoms, underwent nasal lavage with subsequent analysis of inflammation markers, and performed repeated measurements of pulmonary function. Results Measurements in the horse stable showed low organic dust levels and high horse allergen levels. Increased viable level of fungi in the air indicated a growing source in the stable. Air particle load as well as 1,3-β-glucan was higher at the two winter time-points, whereas endotoxin levels were higher at the summer time-point. Two stable-workers showed signs of bronchial obstruction with increased PEF-variability, increased inflammation biomarkers relating to reported allergy, cold or smoking and reported partly work-related symptoms. Furthermore, two other stable-workers reported work-related airway symptoms, of which one had doctor's diagnosed asthma which was well treated. Conclusion Biomarkers involved in the development of airway diseases have been studied in relation to

Influence of horse stable environment on human airways.

Science.gov (United States)

Elfman, Lena; Riihimäki, Miia; Pringle, John; Wålinder, Robert

2009-05-25

Many people spend considerable amount of time each day in equine stable environments either as employees in the care and training of horses or in leisure activity. However, there are few studies available on how the stable environment affects human airways. This study examined in one horse stable qualitative differences in indoor air during winter and late summer conditions and assessed whether air quality was associated with clinically detectable respiratory signs or alterations to selected biomarkers of inflammation and lung function in stable personnel. The horse stable environment and stable-workers (n = 13) in one stable were investigated three times; first in the winter, second in the interjacent late summer and the third time in the following winter stabling period. The stable measurements included levels of ammonia, hydrogen sulphide, total and respirable dust, airborne horse allergen, microorganisms, endotoxin and glucan. The stable-workers completed a questionnaire on respiratory symptoms, underwent nasal lavage with subsequent analysis of inflammation markers, and performed repeated measurements of pulmonary function. Measurements in the horse stable showed low organic dust levels and high horse allergen levels. Increased viable level of fungi in the air indicated a growing source in the stable. Air particle load as well as 1,3-beta-glucan was higher at the two winter time-points, whereas endotoxin levels were higher at the summer time-point. Two stable-workers showed signs of bronchial obstruction with increased PEF-variability, increased inflammation biomarkers relating to reported allergy, cold or smoking and reported partly work-related symptoms. Furthermore, two other stable-workers reported work-related airway symptoms, of which one had doctor's diagnosed asthma which was well treated. Biomarkers involved in the development of airway diseases have been studied in relation to environmental exposure levels in equine stables. Respirable dust and 1

Stable configurations in social networks

Science.gov (United States)

Bronski, Jared C.; DeVille, Lee; Ferguson, Timothy; Livesay, Michael

2018-06-01

We present and analyze a model of opinion formation on an arbitrary network whose dynamics comes from a global energy function. We study the global and local minimizers of this energy, which we call stable opinion configurations, and describe the global minimizers under certain assumptions on the friendship graph. We show a surprising result that the number of stable configurations is not necessarily monotone in the strength of connection in the social network, i.e. the model sometimes supports more stable configurations when the interpersonal connections are made stronger.

Development of Stable Isotope Technology

International Nuclear Information System (INIS)

Jeong, Do Young; Kim, Cheol Jung; Han, Jae Min

2009-03-01

KAERI has obtained an advanced technology with singular originality for laser stable isotope separation. Objectives for this project are to get production technology of Tl-203 stable isotope used for medical application and are to establish the foundation of the pilot system, while we are taking aim at 'Laser Isotope Separation Technology to make resistance to the nuclear proliferation'. And we will contribute to ensuring a nuclear transparency in the world society by taking part in a practical group of NSG and being collaboration with various international groups related to stable isotope separation technology

Calcium stable isotope geochemistry

Energy Technology Data Exchange (ETDEWEB)

Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

2016-08-01

This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

Calcium stable isotope geochemistry

International Nuclear Information System (INIS)

Gausonne, Nikolaus; Schmitt, Anne-Desiree; Heuser, Alexander; Wombacher, Frank; Dietzel, Martin; Tipper, Edward; Schiller, Martin

2016-01-01

This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

Stable isotopes in barnacles as a tool to understand green sea turtle (Chelonia mydas) regional movement patterns

Science.gov (United States)

Detjen, M.; Sterling, E.; Gómez, A.

2015-12-01

Sea turtles are migratory animals that travel long distances between their feeding and breeding grounds. Traditional methods for researching sea turtle migratory behavior have important disadvantages, and the development of alternatives would enhance our ability to monitor and manage these globally endangered species. Here we report on the isotope signatures in green sea-turtle (Chelonia mydas) barnacles (Platylepas sp.) and discuss their potential relevance as tools with which to study green sea turtle migration and habitat use patterns. We analyzed oxygen (δ18O) and carbon (δ13C) isotope ratios in barnacle calcite layers from specimens collected from green turtles captured at the Palmyra Atoll National Wildlife Refuge (PANWR) in the central Pacific. Carbon isotopes were not informative in this study. However, the oxygen isotope results suggest likely regional movement patterns when mapped onto a predictive oxygen isotope map of the Pacific. Barnacle proxies could therefore complement other methods in understanding regional movement patterns, informing more effective conservation policy that takes into account connectivity between populations.

Continuous control of asymmetric forebody vortices in a bi-stable state

Science.gov (United States)

Wang, Qi-te; Cheng, Ke-ming; Gu, Yun-song; Li, Zhuo-qi

2018-02-01

Aiming at the problem of continuous control of asymmetric forebody vortices at a high angle of attack in a bi-stable regime, a dual synthetic jet actuator embedded in an ogive forebody was designed. Alternating unsteady disturbance with varying degree asymmetrical flow fields near the nozzles is generated by adjusting the duty cycle of the drive signal of the actuator, specifically embodying the asymmetric time-averaged pattern of jet velocity, vorticity, and turbulent kinetic energy. Experimental results show that within the range of relatively high angles of attack, including the angle-of-attack region in a bi-stable state, the lateral force of the ogive forebody is continuously controlled by adjusting the duty cycle of the drive signal; the position of the forebody vortices in space, the vorticity magnitude, the total pressure coefficient near the vortex core, and the vortex breakdown location are continuously changed with the duty cycle increased observed from the time-averaged flow field. Instantaneous flow field results indicate that although the forebody vortices are in an unsteady oscillation state, a continuous change in the forebody vortices' oscillation balance position as the duty cycle increases leads to a continuous change in the model's surface pressure distribution and time-averaged lateral force. Different from the traditional control principle, in this study, other different degree asymmetrical states of the forebody vortices except the bi-stable state are obtained using the dual synthetic jet control technology.

Essential roles for lines in mediating leg and antennal proximodistal patterning and generating a stable Notch signaling interface at segment borders.

Science.gov (United States)

Greenberg, Lina; Hatini, Victor

2009-06-01

The Drosophila leg imaginal disc provides a paradigm with which to understand the fundamental developmental mechanisms that generate an intricate appendage structure. Leg formation depends on the subdivision of the leg proximodistal (PD) axis into broad domains by the leg gap genes. The leg gap genes act combinatorially to initiate the expression of the Notch ligands Delta (Dl) and Serrate (Ser) in a segmental pattern. Dl and Ser induce the expression of a set of transcriptional regulators along the segment border, which mediate leg segment growth and joint morphogenesis. Here we show that Lines accumulates in nuclei in the presumptive tarsus and the inter-joints of proximal leg segments and governs the formation of these structures by destabilizing the nuclear protein Bowl. Across the presumptive tarsus, lines modulates the opposing expression landscapes of the leg gap gene dachshund (dac) and the tarsal PD genes, bric-a-brac 2 (bab), apterous (ap) and BarH1 (Bar). In this manner, lines inhibits proximal tarsal fates and promotes medial and distal tarsal fates. Across proximal leg segments, lines antagonizes bowl to promote Dl expression by relief-of-repression. In turn, Dl signals asymmetrically to stabilize Bowl in adjacent distal cells. Bowl, then, acts cell-autonomously, together with one or more redundant factors, to repress Dl expression. Together, lines and bowl act as a binary switch to generate a stable Notch signaling interface between Dl-expressing cells and adjacent distal cell. lines plays analogous roles in developing antennae, which are serially homologous to legs, suggesting evolutionarily conserved roles for lines in ventral appendage formation.

Do Specific Transitional Patterns of Antisocial Behavior during Adolescence Increase Risk for Problems in Young Adulthood?

Science.gov (United States)

Cook, Emily C.; Pflieger, Jacqueline C.; Connell, Arin M.; Connell, Christian M.

2014-01-01

Latent transition analysis was used to identify patterns and trajectories of antisocial behavior (ASB) and their association with young adult outcomes in a nationally representative sample of adolescents (N = 5,422; 53.9% female). Participants were on average 13.96 years of age (SD= 1.06) at wave 1 of the study. Latent class analysis identified four classes of ASB including a non-ASB class, an aggressive class, a petty theft class, and a serious ASB class. In general, youth who were classified as serious stable ASB were the most at risk for problematic functioning in young adulthood. Youth who escalated to more serious patterns of ASB or reduced involvement also were at greater risk of negative outcomes in young adulthood compared to stable non-ASB youth, although they generally fared better than youth involved in stable patterns of more serious ASB. Gender differences indicated that involvement in ASB was a greater risk factor for alcohol use among boys and a greater risk factor for depression among girls in young adulthood. Results are discussed in terms of the predictive validity of classes of ASB to functioning in young adulthood and the implications of this research for prevention efforts. PMID:24893667

Unpredictably Stable

DEFF Research Database (Denmark)

Failla, Virgilio; Melillo, Francesca; Reichstein, Toke

2014-01-01

Is entrepreneurship a more stable career choice for high employment turnover individuals? We find that a transition to entrepreneurship induces a shift towards stayer behavior and identify job matching, job satisfaction and lock-in effects as main drivers. These findings have major implications...

On the physical basis of pattern formation in nonlinear systems

International Nuclear Information System (INIS)

Sanduloviciu, M.; Lozneanu, E.; Popescu, S.

2003-01-01

Spatial, respectively spatiotemporal patterns appear in a gaseous conductor (plasma) when an external constraint produces a local gradient of electron kinetic energy. Under such conditions, collective quantum effects related to the spatial separation of the excitation and ionization cross-sections determine the appearance of adjacent opposite space charges. The state of the resulting space charge configuration depends on the self-enhancement process of positive ions production, which destabilizes the system. Thus, a spatial pattern in the form of a stable double layer appears after self-organization when the above gradient is smaller than that for which the double layer transits into a moving phase (spatiotemporal pattern). The proposed explanation, based on investigations performed on self-organization phenomena observed in gaseous conductors, suggests a new possibility to clarify the challenging problems concerning the actual physical basis of pattern formation in semiconductors

Activity patterns in networks stabilized by background oscillations.

Science.gov (United States)

Hoppensteadt, Frank

2009-07-01

The brain operates in a highly oscillatory environment. We investigate here how such an oscillating background can create stable organized behavior in an array of neuro-oscillators that is not observable in the absence of oscillation, much like oscillating the support point of an inverted pendulum can stabilize its up position, which is unstable without the oscillation. We test this idea in an array of electronic circuits coming from neuroengineering: we show how the frequencies of the background oscillation create a partition of the state space into distinct basins of attraction. Thus, background signals can stabilize persistent activity that is otherwise not observable. This suggests that an image, represented as a stable firing pattern which is triggered by a voltage pulse and is sustained in synchrony or resonance with the background oscillation, can persist as a stable behavior long after the initial stimulus is removed. The background oscillations provide energy for organized behavior in the array, and these behaviors are categorized by the basins of attraction determined by the oscillation frequencies.

Influences of environment and disturbance on forest patterns in coastal Oregon watersheds.

Science.gov (United States)

Michael C. Wimberly; Thomas A. Spies

2001-01-01

Modern ecology often emphasizes the distinction between traditional theories of stable, environmentally structured communities and a new paradigm of disturbance driven, nonequilibrium dynamics. However, multiple hypotheses for observed vegetation patterns have seldom been explicitly tested. We used multivariate statistics and variation partitioning methods to assess...

Variation in catchment areas of Indiana bat (Myotis sodalis) hibernacula inferred from stable hydrogen (δ2H) isotope analysis.

Science.gov (United States)

E.R. Britzke; S.C. Loeb; C.S. Romanek; K.A. Hobson; M.J. Vonhof

2013-01-01

Understanding seasonal movements of bats is important for effective conservation efforts. Although female Indiana bats (Myotis sodalis Miller and Allen, 1928) have been documented to migrate >500 km, knowledge of their migratory patterns is still extremely limited. We used the relationship between latitude and stable hydrogen isotope ratio in bat hair (δ...

Stable isotopes as tracers for radionuclides

International Nuclear Information System (INIS)

Giussani, A.; Bartolo, D. de; Cantone, M.C.; Zilker, T.; Greim, H.; Roth, P.; Werner, E.

2000-01-01

The assessment of internal dose after incorporation of radionuclides requires as input data the knowledge of the uptake into the systemic circulation, the distribution and retention in selected organs, the excretion pathways. Realistic biokinetic models are needed for reliable estimates, correct interpretation of bioassay measurements, appropriate decision-making in radiological emergencies. For many radionuclides, however, the biokinetic models currently recommended are often generic, with very few specific parameters, due to the lack of experimental human data. The use of stable isotopes as tracers enables to determine important biokinetic parameters such as the fractional uptake, the clearance from the transfer compartment, the excretion patterns under experimentally controlled conditions. The subjects investigated are not exposed to any radiation risk, so this technique enables to obtain biokinetic information also for sensitive groups of the population, such as children or pregnant women, and to determine age- and gender-specific model parameters. Sophisticated analytical method, able to discriminate and quantitate different isotopes of the same element in complex matrices such as biological fluids, have to be purposely developed and optimized. Activation analysis and mass spectrometry are the most proper techniques of choice. Experiments were conducted with molybdenum, tellurium, ruthenium and zirconium. Activation analysis with protons, thermal ionization mass spectrometry and inductively coupled mass spectrometry were employed for the determination of stable isotopes of these elements in blood plasma and urine samples. Several deviations from the predictions of the ICRP models were observed. For example, modifications to the current model for molybdenum have been suggested on the basis of these results. The dose coefficients to the target regions calculated with this proposed model are even of one order of magnitude different than the ICRP estimates

Control of Turing patterns and their usage as sensors, memory arrays, and logic gates

Science.gov (United States)

Muzika, František; Schreiber, Igor

2013-10-01

We study a model system of three diffusively coupled reaction cells arranged in a linear array that display Turing patterns with special focus on the case of equal coupling strength for all components. As a suitable model reaction we consider a two-variable core model of glycolysis. Using numerical continuation and bifurcation techniques we analyze the dependence of the system's steady states on varying rate coefficient of the recycling step while the coupling coefficients of the inhibitor and activator are fixed and set at the ratios 100:1, 1:1, and 4:5. We show that stable Turing patterns occur at all three ratios but, as expected, spontaneous transition from the spatially uniform steady state to the spatially nonuniform Turing patterns occurs only in the first case. The other two cases possess multiple Turing patterns, which are stabilized by secondary bifurcations and coexist with stable uniform periodic oscillations. For the 1:1 ratio we examine modular spatiotemporal perturbations, which allow for controllable switching between the uniform oscillations and various Turing patterns. Such modular perturbations are then used to construct chemical computing devices utilizing the multiple Turing patterns. By classifying various responses we propose: (a) a single-input resettable sensor capable of reading certain value of concentration, (b) two-input and three-input memory arrays capable of storing logic information, (c) three-input, three-output logic gates performing combinations of logical functions OR, XOR, AND, and NAND.

45-110 GHz Quad-Ridge Horn With Stable Gain and Symmetric Beam

Science.gov (United States)

Manafi, Sara; Al-Tarifi, Muhannad; Filipovic, Dejan S.

2017-09-01

A quad-ridge horn antenna with stabilized gain and minimum difference between Eand H-plane half-power beamwidths (HPBWs) is demonstrated for operation over 45-110 GHz bandwidth. Multistep flaring and corrugations on a finite ground plane are applied to obtain stable radiation patterns with 16-dBi minimum gain over the entire range. The computational studies are validated through measurements of a 3-D printed prototype using the direct metal laser sintering (DMLS) process. Accurate fabrication with achieved surface roughness of DMLS is a viable fabrication process for wideband horn antennas at millimeter-wave frequencies.

Juvenile life history of NE Atlantic orange roughy from otolith stable isotopes

Science.gov (United States)

Shephard, Samuel; Trueman, Clive; Rickaby, Rosalind; Rogan, Emer

2007-08-01

Otoliths of pre-recruit orange roughy ( Hoplostethus atlanticus) were sampled from different deep-water habitats ('flat' and 'hill') and areas (north and south) on the Porcupine Bank. Age-based profiles for stable isotopes of carbon (δ 13C) and oxygen (δ 18O) in these otoliths were developed, which provide a fish life-history record of water depth and metabolic activity. These profiles were consistent among all individuals implying endogenous (ontogenic) influences on the pattern. The data indicate that post-larval orange roughy are mesopelagic active foragers, early juvenile fish move into a low energy deep-demersal phase, and older pre-recruit orange roughy assume the habitat depth and metabolic rate typical of adults. Comparison of otolith stable isotope profiles among areas and habitats on the Porcupine Bank suggest that juvenile orange roughy from South 'hill' and 'flat' habitats experience differing temperature and metabolic status at certain life stages. This may reflect oceanographic and ecological divergence between the two environments and suggests fine-scale population structure that may reduce resilience to exploitation.

Children's organized physical activity patterns from childhood into adolescence.

Science.gov (United States)

Findlay, Leanne C; Garner, Rochelle E; Kohen, Dafna E

2009-11-01

Few longitudinal studies of physical activity have included young children or used nationally representative datasets. The purpose of the current study was to explore patterns of organized physical activity for Canadian children aged 4 through 17 years. Data from 5 cycles of the National Longitudinal Survey of Children and Youth were analyzed separately for boys (n = 4463) and girls (n = 4354) using multiple trajectory modeling. Boys' and girls' organized physical activity was best represented by 3 trajectory groups. For boys, these groups were labeled: high stable, high decreasing, and low decreasing participation. For girls, these groups were labeled: high decreasing, moderate stable, and low decreasing participation. Risk factors (parental education, household income, urban/rural dwelling, and single/dual parent) were explored. For boys and girls, having a parent with postsecondary education and living in a higher income household were associated with a greater likelihood of weekly participation in organized physical activity. Living in an urban area was also significantly associated with a greater likelihood of weekly participation for girls. Results suggest that Canadian children's organized physical activity is best represented by multiple patterns of participation that tend to peak in middle childhood and decline into adolescence.

Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots

KAUST Repository

Muraro, D.

2013-12-31

As multicellular organisms grow, positional information is continually needed to regulate the pattern in which cells are arranged. In the Arabidopsis root, most cell types are organized in a radially symmetric pattern; however, a symmetry-breaking event generates bisymmetric auxin and cytokinin signaling domains in the stele. Bidirectional cross-talk between the stele and the surrounding tissues involving a mobile transcription factor, SHORT ROOT (SHR), and mobile microRNA species also determines vascular pattern, but it is currently unclear how these signals integrate. We use a multicellular model to determine a minimal set of components necessary for maintaining a stable vascular pattern. Simulations perturbing the signaling network show that, in addition to the mutually inhibitory interaction between auxin and cytokinin, signaling through SHR, microRNA165/6, and PHABULOSA is required to maintain a stable bisymmetric pattern. We have verified this prediction by observing loss of bisymmetry in shr mutants. The model reveals the importance of several features of the network, namely the mutual degradation of microRNA165/6 and PHABULOSA and the existence of an additional negative regulator of cytokinin signaling. These components form a plausible mechanism capable of patterning vascular tissues in the absence of positional inputs provided by the transport of hormones from the shoot.

Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots

KAUST Repository

Muraro, D.; Mellor, N.; Pound, M. P.; Help, H.; Lucas, M.; Chopard, J.; Byrne, H. M.; Godin, C.; Hodgman, T. C.; King, J. R.; Pridmore, T. P.; Helariutta, Y.; Bennett, M. J.; Bishopp, A.

2013-01-01

As multicellular organisms grow, positional information is continually needed to regulate the pattern in which cells are arranged. In the Arabidopsis root, most cell types are organized in a radially symmetric pattern; however, a symmetry-breaking event generates bisymmetric auxin and cytokinin signaling domains in the stele. Bidirectional cross-talk between the stele and the surrounding tissues involving a mobile transcription factor, SHORT ROOT (SHR), and mobile microRNA species also determines vascular pattern, but it is currently unclear how these signals integrate. We use a multicellular model to determine a minimal set of components necessary for maintaining a stable vascular pattern. Simulations perturbing the signaling network show that, in addition to the mutually inhibitory interaction between auxin and cytokinin, signaling through SHR, microRNA165/6, and PHABULOSA is required to maintain a stable bisymmetric pattern. We have verified this prediction by observing loss of bisymmetry in shr mutants. The model reveals the importance of several features of the network, namely the mutual degradation of microRNA165/6 and PHABULOSA and the existence of an additional negative regulator of cytokinin signaling. These components form a plausible mechanism capable of patterning vascular tissues in the absence of positional inputs provided by the transport of hormones from the shoot.

Career patterns and job satisfaction of Canadian nurse educators.

Science.gov (United States)

Barrett, M C; Goldenberg, D; Faux, S

1992-08-01

The purpose of this study was to describe the career patterns and job satisfaction of Ontario university and college nurse educators. A descriptive survey design was employed using mailed questionnaires. The sample comprised 60 nurse educators, 30 from three universities and 30 from three colleges. Forty-four returned the completed questionnaire, giving a response rate of 73%. The variables about the career patterns and goals of the nurse educators included their past and present job satisfaction. Career patterns were described as stable, double-track, interrupted and unstable. Similarities and differences were compared and described in relation to these factors. Significant differences in job satisfaction were found between university and college faculty on nine of the 36 job characteristics (for example, leadership style, independence, autonomy and salary). There were no significant differences in job satisfaction for each of the career patterns and the selected demographic variables of age, years in nursing education, educational level and salary between the university and college faculty.

Pattern formation in three-dimensional reaction-diffusion systems

Science.gov (United States)

Callahan, T. K.; Knobloch, E.

1999-08-01

Existing group theoretic analysis of pattern formation in three dimensions [T.K. Callahan, E. Knobloch, Symmetry-breaking bifurcations on cubic lattices, Nonlinearity 10 (1997) 1179-1216] is used to make specific predictions about the formation of three-dimensional patterns in two models of the Turing instability, the Brusselator model and the Lengyel-Epstein model. Spatially periodic patterns having the periodicity of the simple cubic (SC), face-centered cubic (FCC) or body-centered cubic (BCC) lattices are considered. An efficient center manifold reduction is described and used to identify parameter regimes permitting stable lamellæ, SC, FCC, double-diamond, hexagonal prism, BCC and BCCI states. Both models possess a special wavenumber k* at which the normal form coefficients take on fixed model-independent ratios and both are described by identical bifurcation diagrams. This property is generic for two-species chemical reaction-diffusion models with a single activator and inhibitor.

Stable rotating dipole solitons in nonlocal media

DEFF Research Database (Denmark)

Lopez-Aguayo, Servando; Skupin, Stefan; Desyatnikov, Anton S.

2006-01-01

We present the first example of stable rotating two-soliton bound states in nonlinear optical media with nonlocal response. We show that, in contrast to media with local response, nonlocality opens possibilities to generate stable azimuthons.......We present the first example of stable rotating two-soliton bound states in nonlinear optical media with nonlocal response. We show that, in contrast to media with local response, nonlocality opens possibilities to generate stable azimuthons....

The contribution of proprioceptive information to postural control in elderly and patients with Parkinson’s disease with a history of falls

Directory of Open Access Journals (Sweden)

Esther Maria Johanna Bekkers

2014-11-01

Full Text Available Proprioceptive deficits negatively affect postural control but their precise contribution to postural instability in Parkinson’s disease (PD is unclear. We investigated if proprioceptive manipulations differentially affect balance, measured by force plates, during quiet standing in 13 PD patients and 13 age-matched controls with a history of falls. Perceived limits of stability (LoS were derived from the differences between maximal center of pressure (CoP displacement in anterior-posterior (AP and medio-lateral (ML direction during a maximal leaning task. Task conditions comprised standing with eyes open (EO and eyes closed (EC, (1 on a stable surface; (2 an unstable surface and (3 with Achilles tendon vibration. CoP displacements were calculated as a percentage of their respective LoS. Perceived LoS did not differ between groups. PD patients showed greater ML CoP displacement than elderly fallers (EF across all conditions (p = 0.043 and tended to have higher postural sway in relation to the LoS (p = 0.050. Both groups performed worse on an unstable surface and during tendon vibration compared to standing on a stable surface with EO and even more so with EC. Both PD and EF had more AP sway in all conditions with EC compared to EO (p < 0.001 and showed increased CoP displacements when relying on proprioception only compared to standing with normal sensory input. This implies a similar role of the proprioceptive system in postural control in fallers with and without PD. PD fallers showed higher ML sway after sensory manipulations disturbing postural control, as a result of which these values approached their perceived LoS more closely than in EF. We conclude that despite a similar fall history, PD patients showed more ML instability than EF, irrespective of sensory manipulation, but had a similar reliance on ankle proprioception. Hence, we recommend that rehabilitation and fall prevention for PD should focus on motor rather than on sensory

Application of Stable Isotope-Assisted Metabolomics for Cell Metabolism Studies

Science.gov (United States)

You, Le; Zhang, Baichen; Tang, Yinjie J.

2014-01-01

The applications of stable isotopes in metabolomics have facilitated the study of cell metabolisms. Stable isotope-assisted metabolomics requires: (1) properly designed tracer experiments; (2) stringent sampling and quenching protocols to minimize isotopic alternations; (3) efficient metabolite separations; (4) high resolution mass spectrometry to resolve overlapping peaks and background noises; and (5) data analysis methods and databases to decipher isotopic clusters over a broad m/z range (mass-to-charge ratio). This paper overviews mass spectrometry based techniques for precise determination of metabolites and their isotopologues. It also discusses applications of isotopic approaches to track substrate utilization, identify unknown metabolites and their chemical formulas, measure metabolite concentrations, determine putative metabolic pathways, and investigate microbial community populations and their carbon assimilation patterns. In addition, 13C-metabolite fingerprinting and metabolic models can be integrated to quantify carbon fluxes (enzyme reaction rates). The fluxome, in combination with other “omics” analyses, may give systems-level insights into regulatory mechanisms underlying gene functions. More importantly, 13C-tracer experiments significantly improve the potential of low-resolution gas chromatography-mass spectrometry (GC-MS) for broad-scope metabolism studies. We foresee the isotope-assisted metabolomics to be an indispensable tool in industrial biotechnology, environmental microbiology, and medical research. PMID:24957020

Personality stability is associated with better cognitive performance in adulthood: are the stable more able?

Science.gov (United States)

Graham, Eileen K; Lachman, Margie E

2012-09-01

Although personality is relatively stable over time, there are individual differences in the patterns and magnitude of change. There is some evidence that personality change in adulthood is related to physical health and longevity. The present study expanded this work to consider whether personality stability or change would be associated with better cognitive functioning, especially in later adulthood. A total of 4,974 individuals participated in two waves of The Midlife in the United States Study (MIDUS) in 1994-1995 and 2004-2005. Participants completed the MIDUS personality inventory at both times and the Brief Test of Adult Cognition by Telephone cognitive battery at Time 2. Multiple regression and analysis of covariance analyses showed that, consistent with predictions, individuals remaining stable in openness to experience and neuroticism had faster reaction times and better inductive reasoning than those who changed. Among older adults, those who remained stable or decreased in neuroticism had significantly faster reaction times than those who increased. As predicted, personality stability on some traits was associated with more adaptive cognitive performance on reasoning and reaction time. Personality is discussed as a possible resource for protecting against or minimizing age-related declines in cognition.

Temporal stability of Escherichia coli concentration patterns in two irrigation ponds in Maryland

Science.gov (United States)

Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli is a common microbial indicator used to evaluate recreational and irrigation water quality. We hypothesized that there is a temporally stable pattern of E.coli concentrations ...

Tempered stable laws as random walk limits

OpenAIRE

Chakrabarty, Arijit; Meerschaert, Mark M.

2010-01-01

Stable laws can be tempered by modifying the L\\'evy measure to cool the probability of large jumps. Tempered stable laws retain their signature power law behavior at infinity, and infinite divisibility. This paper develops random walk models that converge to a tempered stable law under a triangular array scheme. Since tempered stable laws and processes are useful in statistical physics, these random walk models can provide a basic physical model for the underlying physical phenomena.

Self-organized dendritic patterns in the polymer Langmuir-Blodgett film

Energy Technology Data Exchange (ETDEWEB)

Matsui, Jun, E-mail: jun_m@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai, 980-8577 (Japan); Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi 332-0012 (Japan); Suzuki, Toshio; Mikayama, Takeshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai, 980-8577 (Japan); Aoki, Atsushi [Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology Gokiso, Shouwa-ku, Nagoya 466-8555 (Japan); Miyashita, Tokuji [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku Sendai, 980-8577 (Japan)

2011-01-03

We report the formation of a self-organized dendritic pattern of nanometer thickness in polymer Langmuir-Blodgett (LB) films. Poly(N-dodecylacrylamide) (pDDA)/chloroform solution was spread on a water surface to form a stable polymer monolayer. A pDDA monolayer was deposited onto a hydrophilic silicon substrate by upward deposition from a water subphase, and a second layer was then deposited by downward deposition. The substrate with the two layers was withdrawn from a clean water surface at a high speed to form the dendritic pattern, which was imaged by atomic force microscopy. The height of the pattern, 3.5 nm, corresponds to the height of a bilayer pDDA LB film, suggesting that the pattern forms when the deposited outermost layer overturns by meniscus oscillation. A similar dendritic structure of narrower width and lower height was fabricated on a hydrophobic silicon substrate.

Auditory cues for orientation and postural control in sighted and congenitally blind people

Science.gov (United States)

Easton, R. D.; Greene, A. J.; DiZio, P.; Lackner, J. R.

1998-01-01

This study assessed whether stationary auditory information could affect body and head sway (as does visual and haptic information) in sighted and congenitally blind people. Two speakers, one placed adjacent to each ear, significantly stabilized center-of-foot-pressure sway in a tandem Romberg stance, while neither a single speaker in front of subjects nor a head-mounted sonar device reduced center-of-pressure sway. Center-of-pressure sway was reduced to the same level in the two-speaker condition for sighted and blind subjects. Both groups also evidenced reduced head sway in the two-speaker condition, although blind subjects' head sway was significantly larger than that of sighted subjects. The advantage of the two-speaker condition was probably attributable to the nature of distance compared with directional auditory information. The results rule out a deficit model of spatial hearing in blind people and are consistent with one version of a compensation model. Analysis of maximum cross-correlations between center-of-pressure and head sway, and associated time lags suggest that blind and sighted people may use different sensorimotor strategies to achieve stability.

The Myopic Stable Set for Social Environments

NARCIS (Netherlands)

Demuynck, Thomas; Herings, P. Jean-Jacques; Saulle, Riccardo; Seel, Christian

2017-01-01

We introduce a new solution concept for models of coalition formation, called the myopic stable set. The myopic stable set is defined for a very general class of social environments and allows for an infinite state space. We show that the myopic stable set exists and is non-empty. Under minor

Dental family stress and coping patterns.

Science.gov (United States)

Nevin, R S; Sampson, V M

1986-10-01

This exploratory study of 28 married male dentists and their families was designed to gain an understanding about the stressors that dentists and their spouses experience, the life events and family strains they incur, the behavioral coping patterns they utilize, and their psychosocial characteristics. The study found that although stable dental families did encounter a significant number of stressors arising from both the dental practice and the family, they maintained their sense of balance through strong family coping skills and family resources. The effect of the dentist's office-related stress was directly felt in the family, especially by the spouse. Strong coping patterns resulted when dentists and spouses maintained a balance of time and responsibility, satisfaction in work and family activity, regular communication, sharing of decision making, good physical health, and the inclusion of an active exercise program within multiple demands on their time.

Stable isotope analysis in primatology: a critical review.

Science.gov (United States)

Sandberg, Paul A; Loudon, James E; Sponheimer, Matt

2012-11-01

Stable isotope analysis has become an important tool in ecology over the last 25 years. A wealth of ecological information is stored in animal tissues in the relative abundances of the stable isotopes of several elements, particularly carbon and nitrogen, because these isotopes navigate through ecological processes in predictable ways. Stable carbon and nitrogen isotopes have been measured in most primate taxonomic groups and have yielded information about dietary content, dietary variability, and habitat use. Stable isotopes have recently proven useful for addressing more fine-grained questions about niche dynamics and anthropogenic effects on feeding ecology. Here, we discuss stable carbon and nitrogen isotope systematics and critically review the published stable carbon and nitrogen isotope data for modern primates with a focus on the problems and prospects for future stable isotope applications in primatology. © 2012 Wiley Periodicals, Inc.

Stable cycling in discrete-time genetic models.

OpenAIRE

Hastings, A

1981-01-01

Examples of stable cycling are discussed for two-locus, two-allele, deterministic, discrete-time models with constant fitnesses. The cases that cycle were found by using numerical techniques to search for stable Hopf bifurcations. One consequence of the results is that apparent cases of directional selection may be due to stable cycling.

Stable cycling in discrete-time genetic models.

Science.gov (United States)

Hastings, A

1981-11-01

Examples of stable cycling are discussed for two-locus, two-allele, deterministic, discrete-time models with constant fitnesses. The cases that cycle were found by using numerical techniques to search for stable Hopf bifurcations. One consequence of the results is that apparent cases of directional selection may be due to stable cycling.

Low-driving-voltage and colour-stable white organic light-emitting diodes with a cross-patterned multi-emissive layer

International Nuclear Information System (INIS)

Hyun, Woo Jin; Park, O Ok; Park, Jae Kyun; Chin, Byung Doo

2012-01-01

We have applied a simple cross-patterning technique for the fabrication of phosphorescent white organic light-emitting diodes (WOLEDs) with red, green and blue (RGB) emitters; the resulting device has relatively low driving voltage and high colour stability. The selectively cross-patterned multicolour emitting layer (EML) was easily prepared using a metal mask without an alignment process. Not only was the characteristic of low driving voltage obtained but also of improved colour stability, which can be ascribed to the simplified stack of the EML and the corresponding suppression of the biased shift in the recombination zone. The spatial distribution and variation of the stacked EML structure could explain the origin of the robust white emission. Compared with the conventional WOLED with a RGB simple stack, the cross-patterned multi-EML device showed a slight change in colour coordinates in the luminance range 100-8000 cd m -2 , with a decrease in the driving voltage of 0.5-2.0 V, while the luminous efficiency was maintained. (paper)

Local Search Approaches in Stable Matching Problems

Directory of Open Access Journals (Sweden)

Toby Walsh

2013-10-01

Full Text Available The stable marriage (SM problem has a wide variety of practical applications, ranging from matching resident doctors to hospitals, to matching students to schools or, more generally, to any two-sided market. In the classical formulation, n men and n women express their preferences (via a strict total order over the members of the other sex. Solving an SM problem means finding a stable marriage where stability is an envy-free notion: no man and woman who are not married to each other would both prefer each other to their partners or to being single. We consider both the classical stable marriage problem and one of its useful variations (denoted SMTI (Stable Marriage with Ties and Incomplete lists where the men and women express their preferences in the form of an incomplete preference list with ties over a subset of the members of the other sex. Matchings are permitted only with people who appear in these preference lists, and we try to find a stable matching that marries as many people as possible. Whilst the SM problem is polynomial to solve, the SMTI problem is NP-hard. We propose to tackle both problems via a local search approach, which exploits properties of the problems to reduce the size of the neighborhood and to make local moves efficiently. We empirically evaluate our algorithm for SM problems by measuring its runtime behavior and its ability to sample the lattice of all possible stable marriages. We evaluate our algorithm for SMTI problems in terms of both its runtime behavior and its ability to find a maximum cardinality stable marriage. Experimental results suggest that for SM problems, the number of steps of our algorithm grows only as O(n log(n, and that it samples very well the set of all stable marriages. It is thus a fair and efficient approach to generate stable marriages. Furthermore, our approach for SMTI problems is able to solve large problems, quickly returning stable matchings of large and often optimal size, despite the

Healthy older adults balance pattern under dual task conditions: exploring the strategy and trend

Directory of Open Access Journals (Sweden)

Bahareh Zeynalzadeh Ghoochani

2016-10-01

Full Text Available Background: In line with health promotion plans, early intervention and fall prevention in geriatric population, it is important to study healthy individuals balance mechanisms. The aim of this research was to investigate the effect of adding and removing visual input and dual task on elderly balance. Methods: Twenty healthy elderly recruited from four different senior citizen health club centers and from the University of Social Welfare and Rehabilitation Sciences (USWR participated in this analytic cross-sectional study. At USWR’s Motor Control Laboratory, the participants’ postural sway were assessed using force plate in 4 distinct double leg standing conditions with and without presence of visual input and Stroop dual task. Postural and Stroop variables were compared. Results: Findings indicated that when the elderly encountered with either dual task or absence of visual input, they can still manage the situation in a way that changes in sway parameter would not become significant. But, when these two conditions occurred simultaneously, the participant’s balance strategy fluctuated. Therefore, the mean velocity showed a significant difference between the "single quiet standing" condition and the condition of standing with eyes closed while the participants were answering Stroop dual task (Mean difference = -0.007, 95% CI = -0.012, -0.002. Conclusion: It appears that velocity parameter is sensitive to small changes, so it is recommended that researchers include this parameter in their future analyses. Balance in elderly can be manipulated by dual task and visual input deprivation.

Stable beams

CERN Multimedia

2015-01-01

Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

Stable isotope research pool inventory

International Nuclear Information System (INIS)

1980-12-01

This report contains a listing of electromagnetically separated stable isotopes which are available for distribution within the United States for non-destructive research use from the Oak Ridge National Laboratory on a loan basis. This inventory includes all samples of stable isotopes in the Materials Research Collection and does not designate whether a sample is out on loan or in reprocessing

Switching among graphic patterns is governed by oscillatory coordination dynamics: Implications for understanding handwriting.

Directory of Open Access Journals (Sweden)

Pier-Giorgio eZanone

2013-09-01

Full Text Available Revisiting an original idea by Hollerbach (1981, previous work has established that the production of graphic shapes, assumed to be the blueprint for handwriting, is governed by the dynamics of orthogonal non-linear coupled oscillators. Such dynamics determines few stable coordination patterns, giving rise to a limited set of preferred graphic shapes, namely, four lines and four ellipsoids independent of orientation. The present study investigates the rules of switching among such graphic coordination patterns. Seven participants were required to voluntarily switch within twelve pairs of shapes presented on a graphic tablet. In line with previous theoretical and experimental work on bimanual coordination, results corroborated our hypothesis that the relative stability of the produced coordination patterns determines the time needed for switching: the transition to a more stable pattern was shorter, and inversely. Moreover, switching between patterns with the same orientation but different eccentricities was faster than with a change in orientation. Nonetheless, the switching time covaried strictly with the change in relative phase effected by the transition between two shapes, whether this implied a change in eccentricity or in orientation. These findings suggest a new operational definition of what the (motor units or strokes of handwriting are and shed a novel light on how co-articulation and recruitment of degrees of freedom may occur in graphic skills. They also yield some leads for understanding the acquisition and the neural underpinnings of handwriting.

Prospective Analysis of Behavioral Economic Predictors of Stable Moderation Drinking Among Problem Drinkers Attempting Natural Recovery.

Science.gov (United States)

Tucker, Jalie A; Cheong, JeeWon; Chandler, Susan D; Lambert, Brice H; Pietrzak, Brittney; Kwok, Heather; Davies, Susan L

2016-12-01

As interventions have expanded beyond clinical treatment to include brief interventions for persons with less severe alcohol problems, predicting who can achieve stable moderation drinking has gained importance. Recent behavioral economic (BE) research on natural recovery has shown that active problem drinkers who allocate their monetary expenditures on alcohol and saving for the future over longer time horizons tend to have better subsequent recovery outcomes, including maintenance of stable moderation drinking. This study compared the predictive utility of this money-based "Alcohol-Savings Discretionary Expenditure" (ASDE) index with multiple BE analogue measures of behavioral impulsivity and self-control, which have seldom been investigated together, to predict outcomes of natural recovery attempts. Community-dwelling problem drinkers, enrolled shortly after stopping abusive drinking without treatment, were followed prospectively for up to a year (N = 175 [75.4% male], M age = 50.65 years). They completed baseline assessments of preresolution drinking practices and problems, analogue behavioral choice tasks (Delay Discounting, Melioration-Maximization, and Alcohol Purchase Tasks), and a Timeline Followback interview including expenditures on alcohol compared to voluntary savings (ASDE index) during the preresolution year. Multinomial logistic regression models showed that, among the BE measures, only the ASDE index predicted stable moderation drinking compared to stable abstinence or unstable resolutions involving relapse. As hypothesized, stable moderation was associated with more balanced preresolution allocations to drinking and savings (odds ratio = 1.77, 95% confidence interval = 1.02 to 3.08, p < 0.05), suggesting it is associated with longer-term behavior regulation processes than abstinence. The ASDE's unique predictive utility may rest on its comprehensive representation of contextual elements to support this patterning of behavioral

Prospective Analysis of Behavioral Economic Predictors of Stable Moderation Drinking Among Problem Drinkers Attempting Natural Recovery

Science.gov (United States)

Tucker, Jalie A.; Cheong, JeeWon; Chandler, Susan D.; Lambert, Brice H.; Pietrzak, Brittney; Kwok, Heather; Davies, Susan L.

2016-01-01

Background As interventions have expanded beyond clinical treatment to include brief interventions for persons with less severe alcohol problems, predicting who can achieve stable moderation drinking has gained importance. Recent behavioral economic (BE) research on natural recovery has shown that active problem drinkers who allocate their monetary expenditures on alcohol and saving for the future over longer time horizons tend to have better subsequent recovery outcomes, including maintenance of stable moderation drinking. The present study compared the predictive utility of this money-based “Alcohol-Savings Discretionary Expenditure” (ASDE) index with multiple BE analogue measures of behavioral impulsivity and self-control, which have seldom been investigated together, to predict outcomes of natural recovery attempts. Methods Community-dwelling problem drinkers, enrolled shortly after stopping abusive drinking without treatment, were followed prospectively for up to a year (N = 175 [75.4% male], M age = 50.65 years). They completed baseline assessments of pre-resolution drinking practices and problems; analogue behavioral choice tasks (Delay Discounting, Melioration-Maximization, and Alcohol Purchase Tasks); and a Timeline Followback interview including expenditures on alcohol compared to voluntary savings (ASDE index) during the pre-resolution year. Results Multinomial logistic regression models showed that, among the BE measures, only the ASDE index predicted stable moderation drinking compared to stable abstinence or unstable resolutions involving relapse. As hypothesized, stable moderation was associated with more balanced pre-resolution allocations to drinking and savings (OR = 1.77, 95% CI = 1.02 ∼ 3.08, p < .05), suggesting it is associated with longer term behavior regulation processes than abstinence. Conclusions The ASDE's unique predictive utility may rest on its comprehensive representation of contextual elements to support this patterning of

Emergent pattern formation in an interstitial biofilm

Science.gov (United States)

Zachreson, Cameron; Wolff, Christian; Whitchurch, Cynthia B.; Toth, Milos

2017-01-01

Collective behavior of bacterial colonies plays critical roles in adaptability, survivability, biofilm expansion and infection. We employ an individual-based model of an interstitial biofilm to study emergent pattern formation based on the assumptions that rod-shaped bacteria furrow through a viscous environment and excrete extracellular polymeric substances which bias their rate of motion. Because the bacteria furrow through their environment, the substratum stiffness is a key control parameter behind the formation of distinct morphological patterns. By systematically varying this property (which we quantify with a stiffness coefficient γ ), we show that subtle changes in the substratum stiffness can give rise to a stable state characterized by a high degree of local order and long-range pattern formation. The ordered state exhibits characteristics typically associated with bacterial fitness advantages, even though it is induced by changes in environmental conditions rather than changes in biological parameters. Our findings are applicable to a broad range of biofilms and provide insights into the relationship between bacterial movement and their environment, and basic mechanisms behind self-organization of biophysical systems.

General asymmetric neutral networks and structure design by genetic algorithms: A learning rule for temporal patterns

Energy Technology Data Exchange (ETDEWEB)

Bornholdt, S. [Heidelberg Univ., (Germany). Inst., fuer Theoretische Physik; Graudenz, D. [Lawrence Berkeley Lab., CA (United States)

1993-07-01

A learning algorithm based on genetic algorithms for asymmetric neural networks with an arbitrary structure is presented. It is suited for the learning of temporal patterns and leads to stable neural networks with feedback.

General asymmetric neutral networks and structure design by genetic algorithms: A learning rule for temporal patterns

International Nuclear Information System (INIS)

Bornholdt, S.

1993-07-01

A learning algorithm based on genetic algorithms for asymmetric neural networks with an arbitrary structure is presented. It is suited for the learning of temporal patterns and leads to stable neural networks with feedback

Numerical approaches to model perturbation fire in turing pattern formations

Science.gov (United States)

Campagna, R.; Brancaccio, M.; Cuomo, S.; Mazzoleni, S.; Russo, L.; Siettos, K.; Giannino, F.

2017-11-01

Turing patterns were observed in chemical, physical and biological systems described by coupled reaction-diffusion equations. Several models have been formulated proposing the water as the causal mechanism of vegetation pattern formation, but this isn't an exhaustive hypothesis in some natural environments. An alternative explanation has been related to the plant-soil negative feedback. In Marasco et al. [1] the authors explored the hypothesis that both mechanisms contribute in the formation of regular and irregular vegetation patterns. The mathematical model consists in three partial differential equations (PDEs) that take into account for a dynamic balance between biomass, water and toxic compounds. A numerical approach is mandatory also to investigate on the predictions of this kind of models. In this paper we start from the mathematical model described in [1], set the model parameters such that the biomass reaches a stable spatial pattern (spots) and present preliminary studies about the occurrence of perturbing events, such as wildfire, that can affect the regularity of the biomass configuration.

Effectiveness and risks of stable iodine prophylaxis

International Nuclear Information System (INIS)

Waight, P.J.

1995-01-01

The factors upon which the efficacy of stable iodine prophylaxis depends are reviewed, with particular reference to the dose of stable iodine, the timing of the dose, the influence of dietary iodine and the impact of the other prospective actions. The risks of stable iodine ingestion are estimated, and their application to the principle of Justification in outlined. (Author)

Ballooning stable high beta tokamak equilibria

International Nuclear Information System (INIS)

Tuda, Takashi; Azumi, Masafumi; Kurita, Gen-ichi; Takizuka, Tomonori; Takeda, Tatsuoki

1981-04-01

The second stable regime of ballooning modes is numerically studied by using the two-dimensional tokamak transport code with the ballooning stability code. Using the simple FCT heating scheme, we find that the plasma can locally enter this second stable regime. And we obtained equilibria with fairly high beta (β -- 23%) stable against ballooning modes in a whole plasma region, by taking into account of finite thermal diffusion due to unstable ballooning modes. These results show that a tokamak fusion reactor can operate in a high beta state, which is economically favourable. (author)

Ground level air convection produces frost damage patterns in turfgrass.

Science.gov (United States)

Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

2015-11-01

Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

Ground level air convection produces frost damage patterns in turfgrass

Science.gov (United States)

Ackerson, Bruce J.; Beier, Richard A.; Martin, Dennis L.

2015-11-01

Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass ( Cynodon species Rich.), zoysiagrass ( Zoysia species Willd.), and buffalograss [ Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

Existence and construction of large stable food webs

Science.gov (United States)

Haerter, Jan O.; Mitarai, Namiko; Sneppen, Kim

2017-09-01

Ecological diversity is ubiquitous despite the restrictions imposed by competitive exclusion and apparent competition. To explain the observed richness of species in a given habitat, food-web theory has explored nonlinear functional responses, self-interaction, or spatial structure and dispersal—model ingredients that have proven to promote stability and diversity. We return instead here to classical Lotka-Volterra equations, where species-species interaction is characterized by a simple product and spatial restrictions are ignored. We quantify how this idealization imposes constraints on coexistence and diversity for many species. To this end, we introduce the concept of free and controlled species and use this to demonstrate how stable food webs can be constructed by the sequential addition of species. The resulting food webs can reach dozens of species and generally yield nonrandom degree distributions in accordance with the constraints imposed through the assembly process. Our model thus serves as a formal starting point for the study of sustainable interaction patterns between species.

Technical Reviews on Pattern Recognition in Process Analytical Technology

International Nuclear Information System (INIS)

Kim, Jong Yun; Choi, Yong Suk; Ji, Sun Kyung; Park, Yong Joon; Song, Kyu Seok; Jung, Sung Hee

2008-12-01

Pattern recognition is one of the first and the most widely adopted chemometric tools among many active research area in chemometrics such as design of experiment(DoE), pattern recognition, multivariate calibration, signal processing. Pattern recognition has been used to identify the origin of a wine and the time of year that the vine was grown by using chromatography, cause of fire by using GC/MS chromatography, detection of explosives and land mines, cargo and luggage inspection in seaports and airports by using a prompt gamma-ray activation analysis, and source apportionment of environmental pollutant by using a stable isotope ratio mass spectrometry. Recently, pattern recognition has been taken into account as a major chemometric tool in the so-called 'process analytical technology (PAT)', which is a newly-developed concept in the area of process analytics proposed by US Food and Drug Administration (US FDA). For instance, identification of raw material by using a pattern recognition analysis plays an important role for the effective quality control of the production process. Recently, pattern recognition technique has been used to identify the spatial distribution and uniformity of the active ingredients present in the product such as tablet by transforming the chemical data into the visual information

Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

Science.gov (United States)

Valenzuela, Luciano O; Chesson, Lesley A; Bowen, Gabriel J; Cerling, Thure E; Ehleringer, James R

2012-01-01

Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰). Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments.

Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

Directory of Open Access Journals (Sweden)

Luciano O Valenzuela

Full Text Available Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization. Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13C values (-22.7 to -18.3‰, and significantly higher δ(15N (7.8 to 10.3‰ and δ(34S (4.8 to 8.3‰ values than samples from the USA (δ(13C: -21.9 to -15.0‰, δ(15N: 6.7 to 9.9‰, δ(34S: -1.2 to 9.9‰. Within Europe, we detected differences in hair δ(13C and δ(34S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments.

Instabilities of convection patterns in a shear-thinning fluid between plates of finite conductivity

Science.gov (United States)

Varé, Thomas; Nouar, Chérif; Métivier, Christel

2017-10-01

Rayleigh-Bénard convection in a horizontal layer of a non-Newtonian fluid between slabs of arbitrary thickness and finite thermal conductivity is considered. The first part of the paper deals with the primary bifurcation and the relative stability of convective patterns at threshold. Weakly nonlinear analysis combined with Stuart-Landau equation is used. The competition between squares and rolls, as a function of the shear-thinning degree of the fluid, the slabs' thickness, and the ratio of the thermal conductivity of the slabs to that of the fluid is investigated. Computations of heat transfer coefficients are in agreement with the maximum heat transfer principle. The second part of the paper concerns the stability of the convective patterns toward spatial perturbations and the determination of the band width of the stable wave number in the neighborhood of the critical Rayleigh number. The approach used is based on the Ginzburg-Landau equations. The study of rolls stability shows that: (i) for low shear-thinning effects, the band of stable wave numbers is bounded by zigzag instability and cross-roll instability. Furthermore, the marginal cross-roll stability boundary enlarges with increasing shear-thinning properties; (ii) for high shear-thinning effects, Eckhaus instability becomes more dangerous than cross-roll instability. For square patterns, the wave number selection is always restricted by zigzag instability and by "rectangular Eckhaus" instability. In addition, the width of the stable wave number decreases with increasing shear-thinning effects. Numerical simulations of the planform evolution are also presented to illustrate the different instabilities considered in the paper.

Complexity-Based Measures Inform Effects of Tai Chi Training on Standing Postural Control: Cross-Sectional and Randomized Trial Studies

Science.gov (United States)

Wayne, Peter M.; Gow, Brian J.; Costa, Madalena D.; Peng, C.-K.; Lipsitz, Lewis A.; Hausdorff, Jeffrey M.; Davis, Roger B.; Walsh, Jacquelyn N.; Lough, Matthew; Novak, Vera; Yeh, Gloria Y.; Ahn, Andrew C.; Macklin, Eric A.; Manor, Brad

2014-01-01

Background Diminished control of standing balance, traditionally indicated by greater postural sway magnitude and speed, is associated with falls in older adults. Tai Chi (TC) is a multisystem intervention that reduces fall risk, yet its impact on sway measures vary considerably. We hypothesized that TC improves the integrated function of multiple control systems influencing balance, quantifiable by the multi-scale “complexity” of postural sway fluctuations. Objectives To evaluate both traditional and complexity-based measures of sway to characterize the short- and potential long-term effects of TC training on postural control and the relationships between sway measures and physical function in healthy older adults. Methods A cross-sectional comparison of standing postural sway in healthy TC-naïve and TC-expert (24.5±12 yrs experience) adults. TC-naïve participants then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Postural sway was assessed before and after the training during standing on a force-plate with eyes-open (EO) and eyes-closed (EC). Anterior-posterior (AP) and medio-lateral (ML) sway speed, magnitude, and complexity (quantified by multiscale entropy) were calculated. Single-legged standing time and Timed-Up–and-Go tests characterized physical function. Results At baseline, compared to TC-naïve adults (n = 60, age 64.5±7.5 yrs), TC-experts (n = 27, age 62.8±7.5 yrs) exhibited greater complexity of sway in the AP EC (P = 0.023), ML EO (Padults. Trial Registration ClinicalTrials.gov NCT01340365 PMID:25494333

Wettability transition of plasma-treated polystyrene micro/nano pillars-aligned patterns

Directory of Open Access Journals (Sweden)

2010-12-01

Full Text Available This paper reports the wettability transition of plasma-treated polystyrene (PS micro/nano pillars-aligned patterns. The micro/nano pillars were prepared using hot embossing on silicon microporous template and alumina nanoporous template, which were fabricated by ultraviolet (UV lithography and inductive coupled plasma (ICP etching, and two-step anodic oxidation, respectively. The results indicate that the combination of micro/nano patterning and plasma irradiation can easily regulate wettabilities of PS surfaces, i.e. from hydrophilicity to hydrophobicity, or from hydrophobicity to superhydrophilicity. During the wettability transition from hydrophobicity to hydrophilicity there is only mild hydrophilicity loss. After plasma irradiation, moreover, the wettability of PS micro/nano pillars-aligned patterns is more stable than that of flat PS surfaces. The observed wettability transition and wettability stability of PS micro/nano pillars-aligned patterns are new phenomena, which may have potential in creating programmable functional polymer surfaces.

Local control of globally competing patterns in coupled Swift-Hohenberg equations

Science.gov (United States)

Becker, Maximilian; Frenzel, Thomas; Niedermayer, Thomas; Reichelt, Sina; Mielke, Alexander; Bär, Markus

2018-04-01

We present analytical and numerical investigations of two anti-symmetrically coupled 1D Swift-Hohenberg equations (SHEs) with cubic nonlinearities. The SHE provides a generic formulation for pattern formation at a characteristic length scale. A linear stability analysis of the homogeneous state reveals a wave instability in addition to the usual Turing instability of uncoupled SHEs. We performed weakly nonlinear analysis in the vicinity of the codimension-two point of the Turing-wave instability, resulting in a set of coupled amplitude equations for the Turing pattern as well as left- and right-traveling waves. In particular, these complex Ginzburg-Landau-type equations predict two major things: there exists a parameter regime where multiple different patterns are stable with respect to each other and that the amplitudes of different patterns interact by local mutual suppression. In consequence, different patterns can coexist in distinct spatial regions, separated by localized interfaces. We identified specific mechanisms for controlling the position of these interfaces, which distinguish what kinds of patterns the interface connects and thus allow for global pattern selection. Extensive simulations of the original SHEs confirm our results.

Lead-210, polonium-210, and stable lead in the food-chain lichen, reindeer and man

International Nuclear Information System (INIS)

Persson, B.R.

1972-01-01

The measurements of stable lead and the natural fallout radionuclides lead-210 and polonium-210 in communities of lichen (Cladonia alpestris) in central Sweden from 1961 to 1970 indicate a quite constant level. The average lead-210 content per unit area in lichen carpets was found to be 15 +- 2 nCi m -2 , the average lead-210 activity concentration 6.7 +- 0.9 nCi per kg dry weight and the lead-210 specific activity 630 +- 60 nCi per g of stable lead. The polonium-210/lead-210 activity ratio was about 0.9 +- 0.1. The vertical distribution of lead-210 in the lichen carpet showed a maximum concentration in the top layer. The distribution was similar during 1967 and 1968 but the low amount of precipitation during 1968 and 1969 disturbed the distribution pattern in 1969 and 1970. The transfer of lead-210, polonium-210 and stable lead through the food chain: lichen, reindeer, and man was characterized. The absorbed dose rate in Lapps due to polonium-210 was estimated to be about 6 to 8 mrad per year in gonads and 8 to 20 mrad per year in bone tissues. This is about ten percent of their entire absorbed dose contribution from all natural radiation sources. (U.S.)

Tukey max-stable processes for spatial extremes

KAUST Repository

Xu, Ganggang

2016-09-21

We propose a new type of max-stable process that we call the Tukey max-stable process for spatial extremes. It brings additional flexibility to modeling dependence structures among spatial extremes. The statistical properties of the Tukey max-stable process are demonstrated theoretically and numerically. Simulation studies and an application to Swiss rainfall data indicate the effectiveness of the proposed process. © 2016 Elsevier B.V.

Stable Myoelectric Control of a Hand Prosthesis using Non-Linear Incremental Learning

Directory of Open Access Journals (Sweden)

Arjan eGijsberts

2014-02-01

Full Text Available Stable myoelectric control of hand prostheses remains an open problem. The only successful human-machine interface is surface electromyography, typically allowing control of a few degrees of freedom. Machine learning techniques may have the potential to remove these limitations, but their performance is thus far inadequate: myoelectric signals change over time under the influence of various factors, deteriorating control performance. It is therefore necessary, in the standard approach, to regularly retrain a new model from scratch.We hereby propose a non-linear incremental learning method in which occasional updates with a modest amount of novel training data allow continual adaptation to the changes in the signals. In particular, Incremental Ridge Regression and an approximation of the Gaussian Kernel known as Random Fourier Features are combined to predict finger forces from myoelectric signals, both finger-by-finger and grouped in grasping patterns.We show that the approach is effective and practically applicable to this problem by first analyzing its performance while predicting single-finger forces. Surface electromyography and finger forces were collected from 10 intact subjects during four sessions spread over two different days; the results of the analysis show that small incremental updates are indeed effective to maintain a stable level of performance.Subsequently, we employed the same method on-line to teleoperate a humanoid robotic arm equipped with a state-of-the-art commercial prosthetic hand. The subject could reliably grasp, carry and release everyday-life objects, enforcing stable grasping irrespective of the signal changes, hand/arm movements and wrist pronation and supination.

Left Hand Thumb Imprint Patterns Among Medical Students.

Science.gov (United States)

Khan, Omair; Haroon, Muhammad Zeeshan; Rashid, Muhammad Adnan; Khan, Muhammad Naseem; Khan, Delawar

2017-01-01

Finger printing is an absolute method of identification. Recovery of finger prints from a crime scene is an important method of Forensic identification. Human finger prints are detailed, unique, difficult to alter, easily classifiable and durable over life making them stable and long-term tool of human identification. This cross-sectional study was conducted on 95,3rd year MBBS students of Ayub Medical College Abbottabad from December 2014 to August 2015 to establish the frequency of left hand thumb imprints by rolling and plain method. Study shows Loops among most common finger print pattern in 55 (58%) students out of 95, followed by whorls 33 (35%), arches 5 (5%) and composite 2 (2%). It is thus concluded that most common finger print pattern is loops followed by whorls, arches and composite.

Chance and stability stable distributions and their applications

CERN Document Server

Uchaikin, Vladimir V

1999-01-01

An introduction to the theory of stable distributions and their applications. It contains a modern outlook on the mathematical aspects of the theory. The authors explain numerous peculiarities of stable distributions and describe the principle concept of probability theory and function analysis. A significant part of the book is devoted to applications of stable distributions. Another notable feature is the material on the interconnection of stable laws with fractals, chaos and anomalous transport processes.

French days on stable isotopes

International Nuclear Information System (INIS)

2000-01-01

These first French days on stable isotopes took place in parallel with the 1. French days of environmental chemistry. Both conferences had common plenary sessions. The conference covers all aspects of the use of stable isotopes in the following domains: medicine, biology, environment, tracer techniques, agronomy, food industry, geology, petroleum geochemistry, cosmo-geochemistry, archaeology, bio-geochemistry, hydrology, climatology, nuclear and particle physics, astrophysics, isotope separations etc.. Abstracts available on CD-Rom only. (J.S.)

Pharmaceuticals labelled with stable isotopes

International Nuclear Information System (INIS)

Krumbiegel, P.

1986-11-01

The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

Development of a Safety Management Web Tool for Horse Stables.

Science.gov (United States)

Leppälä, Jarkko; Kolstrup, Christina Lunner; Pinzke, Stefan; Rautiainen, Risto; Saastamoinen, Markku; Särkijärvi, Susanna

2015-11-12

Managing a horse stable involves risks, which can have serious consequences for the stable, employees, clients, visitors and horses. Existing industrial or farm production risk management tools are not directly applicable to horse stables and they need to be adapted for use by managers of different types of stables. As a part of the InnoEquine project, an innovative web tool, InnoHorse, was developed to support horse stable managers in business, safety, pasture and manure management. A literature review, empirical horse stable case studies, expert panel workshops and stakeholder interviews were carried out to support the design. The InnoHorse web tool includes a safety section containing a horse stable safety map, stable safety checklists, and examples of good practices in stable safety, horse handling and rescue planning. This new horse stable safety management tool can also help in organizing work processes in horse stables in general.

Regional hardening of Upper Cretaceous Chalk in eastern England, UK: trace element and stable isotope patterns in the Upper Cenomanian and Turonian Chalk and their significance

Science.gov (United States)

Jeans, Christopher V.; Long, Dee; Hu, Xiu-Fang; Mortimore, Rory N.

2014-12-01

The regional hardening of the Late Cenomanian to Early Turonian Chalk of the Northern Province of eastern England has been investigated by examining the pattern of trace elements and stable carbon and oxygen isotopes in the bulk calcite of two extensive and stratigraphically adjacent units each 4 to 5 m thick of hard chalk in Lincolnshire and Yorkshire. These units are separated by a sequence, 0.3-1.3 m thick, of variegated marls and clayey marls. Modelling of the geochemistry of the hard chalk by comparison with the Standard Louth Chalk, combined with associated petrographic and geological evidence, indicates that (1) the hardening is due to the precipitation of a calcite cement, and (2) the regional and stratigraphical patterns of geochemical variation in the cement are largely independent of each other and have been maintained by the impermeable nature of the thin sequence of the clay-rich marls that separate them. Two phases of calcite cementation are recognised. The first phase was microbially influenced and did not lithify the chalk. It took place predominantly in oxic and suboxic conditions under considerable overpressure in which the Chalk pore fluids circulated within the units, driven by variations in compaction, temperature, pore fluid pressure and local tectonics. There is evidence in central and southern Lincolnshire of the loss of Sr and Mgenriched pore fluids to the south during an early part of this phase. The second phase of calcite precipitation was associated with the loss of overpressure in probably Late Cretaceous and in Cenozoic times as the result of fault movement in the basement penetrating the overlying Chalk and damaging the seal between the two chalk units. This greatly enhanced grain pressures, resulting in grain welding and pressure dissolution, causing lithification with the development of stylolites, marl seams, and brittle fractures. Associated with this loss of overpressure was the penetration of the chalk units by allochthonous

Tempered stable distributions stochastic models for multiscale processes

CERN Document Server

Grabchak, Michael

2015-01-01

This brief is concerned with tempered stable distributions and their associated Levy processes. It is a good text for researchers interested in learning about tempered stable distributions.  A tempered stable distribution is one which takes a stable distribution and modifies its tails to make them lighter. The motivation for this class comes from the fact that infinite variance stable distributions appear to provide a good fit to data in a variety of situations, but the extremely heavy tails of these models are not realistic for most real world applications. The idea of using distributions that modify the tails of stable models to make them lighter seems to have originated in the influential paper of Mantegna and Stanley (1994). Since then, these distributions have been extended and generalized in a variety of ways. They have been applied to a wide variety of areas including mathematical finance, biostatistics,computer science, and physics.

Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

Directory of Open Access Journals (Sweden)

Thomas Larsen

Full Text Available Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13C patterns among amino acids (δ(13CAA could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13CAA patterns in contrast to bulk δ(13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

Science.gov (United States)

Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M; Piatkowski, Uwe; McCarthy, Matthew D

2013-01-01

Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13)C patterns among amino acids (δ(13)CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13)CAA patterns in contrast to bulk δ(13)C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13)CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13)C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13)C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

Flying Drosophilamelanogaster maintain arbitrary but stable headings relative to the angle of polarized light.

Science.gov (United States)

Warren, Timothy L; Weir, Peter T; Dickinson, Michael H

2018-05-11

Animals must use external cues to maintain a straight course over long distances. In this study, we investigated how the fruit fly Drosophila melanogaster selects and maintains a flight heading relative to the axis of linearly polarized light, a visual cue produced by the atmospheric scattering of sunlight. To track flies' headings over extended periods, we used a flight simulator that coupled the angular velocity of dorsally presented polarized light to the stroke amplitude difference of the animals' wings. In the simulator, most flies actively maintained a stable heading relative to the axis of polarized light for the duration of 15 min flights. We found that individuals selected arbitrary, unpredictable headings relative to the polarization axis, which demonstrates that D . melanogaster can perform proportional navigation using a polarized light pattern. When flies flew in two consecutive bouts separated by a 5 min gap, the two flight headings were correlated, suggesting individuals retain a memory of their chosen heading. We found that adding a polarized light pattern to a light intensity gradient enhanced flies' orientation ability, suggesting D . melanogaster use a combination of cues to navigate. For both polarized light and intensity cues, flies' capacity to maintain a stable heading gradually increased over several minutes from the onset of flight. Our findings are consistent with a model in which each individual initially orients haphazardly but then settles on a heading which is maintained via a self-reinforcing process. This may be a general dispersal strategy for animals with no target destination. © 2018. Published by The Company of Biologists Ltd.

From Patterns to Function in Living Systems: Dryland Ecosystems as a Case Study

Science.gov (United States)

Meron, Ehud

2018-03-01

Spatial patterns are ubiquitous in animate matter. Besides their intricate structure and beauty they generally play functional roles. The capacity of living systems to remain functional in changing environments is a question of utmost importance, but its intimate relationship to pattern formation is largely unexplored. Here, we address this relationship using dryland vegetation as a case study. Following a brief introduction to pattern-formation theory, we describe a mathematical model that captures several mechanisms of vegetation pattern formation and discuss ecological contexts that showcase different mechanisms. Using this model, we unravel the different vegetation patterns that keep dryland ecosystems viable along the rainfall gradient, identify multistability ranges where fronts separating domains of alternative stable states exist, and highlight the roles of front dynamics in mitigating or reversing desertification. The utility of satellite images in testing model predictions is discussed. An outlook on outstanding open problems concludes this paper.

The Speed Control of Constant Tension Motor of Marine Crane

Directory of Open Access Journals (Sweden)

Chen Xinyang

2016-01-01

Full Text Available This article describes the working principle of the marine beacon crane hanging disc mechanical anti-sway device, and establish mathematical model on the rope controlling hanging disc of mechanical anti-sway device; Through matlab simulation analysis, this article obtains the relation curve between the velocity of traction rope of hanging disc and output frequency of the crane motor, combining rotary crane scaled model, this article carries out anti-sway experiment for the rotary crane to examine the crane’s anti-sway effects.

運動中の姿勢制御と重心移動の関係に関する考察

OpenAIRE

朴沢, 二郎; Jiro, Hozawa; 仙台大学; Sendai College

1997-01-01

The speed of lateral body sway during the movements was recorded by the gravicorder (NEC 1G06) from 12 subjects with normal equilirium function, and the following results were obtainded; 1) When the sway action was performed on the horizontal platform of the gravicorder, there was no directional preponderance in sway speed of all subjects. 2) When the platform was tilted to the right or left, all subjects swayed faster to the tilted side. 3) When the subjects stooped as to lower their gravity...

Magnesium stable isotope ecology using mammal tooth enamel

Science.gov (United States)

Martin, Jeremy E.; Vance, Derek; Balter, Vincent

2015-01-01

Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ13C) and to a lesser extent on strontium/calcium (Sr/Ca) and barium/calcium (Ba/Ca) elemental ratios. Recent developments in nontraditional stable isotopes provide an unprecedented opportunity to use additional paleodietary proxies to disentangle complex diets such as omnivory. Of particular relevance for paleodietary reconstruction are metals present in large quantity in bone and enamel apatite, providing that biologically mediated fractionation processes are constrained. Calcium isotope ratios (δ44Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ26Mg) also meet these criteria but a comprehensive understanding of its variability awaits new isotopic data. Here, 11 extant mammal species of known ecology from a single locality in equatorial Africa were sampled for tooth enamel and, together with vegetation and feces, analyzed for δ26Mg, δ13C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ26Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this 26Mg enrichment up the trophic chain is due to a 26Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ26Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ26Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages.

Stable isotope research pool inventory

International Nuclear Information System (INIS)

1984-03-01

This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

Patterning of the turtle shell.

Science.gov (United States)

Moustakas-Verho, Jacqueline E; Cebra-Thomas, Judith; Gilbert, Scott F

2017-08-01

Interest in the origin and evolution of the turtle shell has resulted in a most unlikely clade becoming an important research group for investigating morphological diversity in developmental biology. Many turtles generate a two-component shell that nearly surrounds the body in a bony exoskeleton. The ectoderm covering the shell produces epidermal scutes that form a phylogenetically stable pattern. In some lineages, the bones of the shell and their ectodermal covering become reduced or lost, and this is generally associated with different ecological habits. The similarity and diversity of turtles allows research into how changes in development create evolutionary novelty, interacting modules, and adaptive physiology and anatomy. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparison of the accuracy of patterns processed from an inlay casting wax, an auto-polymerized resin and a light-cured resin pattern material.

Science.gov (United States)

Rajagopal, Praveen; Chitre, Vidya; Aras, Meena A

2012-01-01

Traditionally, inlay casting waxes have been used to fabricate patterns for castings. Newer resin pattern materials offer greater rigidity and strength, allowing easier laboratory and intraoral adjustment without the fear of pattern damage. They also claim to possess a greater dimensional stability when compared to inlay wax. This study attempted to determine and compare the marginal accuracy of patterns fabricated from an inlay casting wax, an autopolymerized pattern resin and a light polymerized pattern resin on storage off the die for varying time intervals. Ten patterns each were fabricated from an inlay casting wax (GC Corp., Tokyo, Japan), an autopolymerized resin pattern material (Pattern resin, GC Corp, Tokyo, Japan) and a light-cured resin pattern material (Palavit GLC, Hereaus Kulzer GmbH, Germany). The completed patterns were stored off the die at room temperature. Marginal gaps were evaluated by reseating the patterns on their respective dies and observing it under a stereomicroscope at 1, 12, and 24 h intervals after pattern fabrication. The results revealed that the inlay wax showed a significantly greater marginal discrepancy at the 12 and 24 h intervals. The autopolymerized resin showed an initial (at 1 h) marginal discrepancy slightly greater than inlay wax, but showed a significantly less marginal gap (as compared to inlay wax) at the other two time intervals. The light-cured resin proved to be significantly more dimensionally stable, and showed minimal change during the storage period. The resin pattern materials studied, undergo a significantly less dimensional change than the inlay waxes on prolonged storage. They would possibly be a better alternative to inlay wax in situations requiring high precision or when delayed investment (more than 1 h) of patterns can be expected.

Linking foraging strategies of marine calanoid copepods to patterns of nitrogen stable isotope signatures in a mesocosm study

DEFF Research Database (Denmark)

Sommer, Frank; Saage, A.; Santer, B.

2005-01-01

foraging mode and, further, with its nitrogen stable isotope signature (delta(15)N). This is because a more carnivorous diet may be expected to result in a higher delta(15)N. We tested this hypothesis in a mesocosm study using a density gradient (0 to 80 ind. 1(-1)) of calanoid copepods. We expected......The foraging modes of calanoid copepods differ in that stationary suspension-feeding is more easily detected by prey with strong escape responses (ciliates) than is 'cruising' or 'ambushing' feeding. Thus, the ability of a copepod to include heterotrophic prey in its diet may be associated with its...

Complexity-Based Measures Inform Effects of Tai Chi Training on Standing Postural Control: Cross-Sectional and Randomized Trial Studies.

Science.gov (United States)

Wayne, Peter M; Gow, Brian J; Costa, Madalena D; Peng, C-K; Lipsitz, Lewis A; Hausdorff, Jeffrey M; Davis, Roger B; Walsh, Jacquelyn N; Lough, Matthew; Novak, Vera; Yeh, Gloria Y; Ahn, Andrew C; Macklin, Eric A; Manor, Brad

2014-01-01

Diminished control of standing balance, traditionally indicated by greater postural sway magnitude and speed, is associated with falls in older adults. Tai Chi (TC) is a multisystem intervention that reduces fall risk, yet its impact on sway measures vary considerably. We hypothesized that TC improves the integrated function of multiple control systems influencing balance, quantifiable by the multi-scale "complexity" of postural sway fluctuations. To evaluate both traditional and complexity-based measures of sway to characterize the short- and potential long-term effects of TC training on postural control and the relationships between sway measures and physical function in healthy older adults. A cross-sectional comparison of standing postural sway in healthy TC-naïve and TC-expert (24.5±12 yrs experience) adults. TC-naïve participants then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Postural sway was assessed before and after the training during standing on a force-plate with eyes-open (EO) and eyes-closed (EC). Anterior-posterior (AP) and medio-lateral (ML) sway speed, magnitude, and complexity (quantified by multiscale entropy) were calculated. Single-legged standing time and Timed-Up-and-Go tests characterized physical function. At baseline, compared to TC-naïve adults (n = 60, age 64.5±7.5 yrs), TC-experts (n = 27, age 62.8±7.5 yrs) exhibited greater complexity of sway in the AP EC (P = 0.023), ML EO (P<0.001), and ML EC (P<0.001) conditions. Traditional measures of sway speed and magnitude were not significantly lower among TC-experts. Intention-to-treat analyses indicated no significant effects of short-term TC training; however, increases in AP EC and ML EC complexity amongst those randomized to TC were positively correlated with practice hours (P = 0.044, P = 0.018). Long- and short-term TC training were positively associated with physical function. Multiscale entropy offers a complementary

Complexity-Based Measures Inform Effects of Tai Chi Training on Standing Postural Control: Cross-Sectional and Randomized Trial Studies.

Directory of Open Access Journals (Sweden)

Peter M Wayne

Full Text Available Diminished control of standing balance, traditionally indicated by greater postural sway magnitude and speed, is associated with falls in older adults. Tai Chi (TC is a multisystem intervention that reduces fall risk, yet its impact on sway measures vary considerably. We hypothesized that TC improves the integrated function of multiple control systems influencing balance, quantifiable by the multi-scale "complexity" of postural sway fluctuations.To evaluate both traditional and complexity-based measures of sway to characterize the short- and potential long-term effects of TC training on postural control and the relationships between sway measures and physical function in healthy older adults.A cross-sectional comparison of standing postural sway in healthy TC-naïve and TC-expert (24.5±12 yrs experience adults. TC-naïve participants then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Postural sway was assessed before and after the training during standing on a force-plate with eyes-open (EO and eyes-closed (EC. Anterior-posterior (AP and medio-lateral (ML sway speed, magnitude, and complexity (quantified by multiscale entropy were calculated. Single-legged standing time and Timed-Up-and-Go tests characterized physical function.At baseline, compared to TC-naïve adults (n = 60, age 64.5±7.5 yrs, TC-experts (n = 27, age 62.8±7.5 yrs exhibited greater complexity of sway in the AP EC (P = 0.023, ML EO (P<0.001, and ML EC (P<0.001 conditions. Traditional measures of sway speed and magnitude were not significantly lower among TC-experts. Intention-to-treat analyses indicated no significant effects of short-term TC training; however, increases in AP EC and ML EC complexity amongst those randomized to TC were positively correlated with practice hours (P = 0.044, P = 0.018. Long- and short-term TC training were positively associated with physical function.Multiscale entropy offers a complementary

Three-dimensional chimera patterns in networks of spiking neuron oscillators

Science.gov (United States)

Kasimatis, T.; Hizanidis, J.; Provata, A.

2018-05-01

We study the stable spatiotemporal patterns that arise in a three-dimensional (3D) network of neuron oscillators, whose dynamics is described by the leaky integrate-and-fire (LIF) model. More specifically, we investigate the form of the chimera states induced by a 3D coupling matrix with nonlocal topology. The observed patterns are in many cases direct generalizations of the corresponding two-dimensional (2D) patterns, e.g., spheres, layers, and cylinder grids. We also find cylindrical and "cross-layered" chimeras that do not have an equivalent in 2D systems. Quantitative measures are calculated, such as the ratio of synchronized and unsynchronized neurons as a function of the coupling range, the mean phase velocities, and the distribution of neurons in mean phase velocities. Based on these measures, the chimeras are categorized in two families. The first family of patterns is observed for weaker coupling and exhibits higher mean phase velocities for the unsynchronized areas of the network. The opposite holds for the second family, where the unsynchronized areas have lower mean phase velocities. The various measures demonstrate discontinuities, indicating criticality as the parameters cross from the first family of patterns to the second.

Spatiotemporal throughfall patterns beneath an urban tree row

Science.gov (United States)

Bogeholz, P.; Van Stan, J. T., II; Hildebrandt, A.; Friesen, J.; Dibble, M.; Norman, Z.

2016-12-01

Much recent research has focused on throughfall patterns in natural forests as they can influence the heterogeneity of surface ecohydrological and biogeochemical processes. However, to the knowledge of the authors, no work has assessed how urban forest structures affect the spatiotemporal variability of throughfall water flux. Urbanization greatly alters not only a significant portion of the land surface, but canopy structure, with the most typical urban forest configuration being landscaped tree rows along streets, swales, parking lot medians, etc. This study examines throughfall spatiotemporal patterns for a landscaped tree row of Pinus elliottii (Engelm., slash pine) on Georgia Southern University's campus (southeastern, USA) using 150 individual observations per storm. Throughfall correlation lengths beneath this tree row were similar to, but appeared to be more stable across storm size than, observations in past studies on natural forests. Individual tree overlap and the planting interval also may more strongly drive throughfall patterns in tree rows. Meteorological influences beyond storm magnitude (intensity, intermittency, wind conditions, and atmospheric moisture demand) are also examined.

Metabolic studies in man using stable isotopes

International Nuclear Information System (INIS)

Faust, H.; Jung, K.; Krumbiegel, P.

1993-01-01

In this project, stable isotope compounds and stable isotope pharmaceuticals were used (with emphasis on the application of 15 N) to study several aspects of nitrogen metabolism in man. Of the many methods available, the 15 N stable isotope tracer technique holds a special position because the methodology for application and nitrogen isotope analysis is proven and reliable. Valid routine methods using 15 N analysis by emission spectrometry have been demonstrated. Several methods for the preparation of biological material were developed during our participation in the Coordinated Research Programme. In these studies, direct procedures (i.e. use of diluted urine as a samples without chemical preparation) or rapid isolation methods were favoured. Within the scope of the Analytical Quality Control Service (AQCS) enriched stable isotope reference materials for medical and biological studies were prepared and are now available through the International Atomic Energy Agency. The materials are of special importance as the increasing application of stable isotopes as tracers in medical, biological and agricultural studies has focused interest on reliable measurements of biological material of different origin. 24 refs

Rambling and trembling in response to body loading.

Science.gov (United States)

Tahayor, Behdad; Riley, Zachary A; Mahmoudian, Armaghan; Koceja, David M; Hong, Siang Lee

2012-04-01

Various studies have suggested that postural sway is controlled by at least two subsystems. Rambling-Trembling analysis is a widely accepted methodology to dissociate the signals generated by these two hypothetical subsystems. The core assumption of this method is based on the equilibrium point hypothesis which suggests that the central nervous system preserves upright standing by transiently shifting the center of pressure (COP) from one equilibrium point to another. The trajectory generated by this shifting is referred to as rambling and its difference from the original COP signal is referred to as trembling. In this study we showed that these two components of COP are differentially affected when standing with external loads. Using Detrended Fluctuation analysis, we compared the pattern of these two signals in different configurations of body loading. Our findings suggest that by applying an external load, the dynamics of the trembling component is altered independently of the area of postural sway and also independently of the rambling component. The dynamics of rambling changed only during the backloading condition in which the postural sway area also substantially increased. It can be suggested that during loaded standing, the trembling mechanism (which is suggested to be activated by peripheral mechanisms and reflexes) is altered without affecting the central influence on the shifts of the equilibrium point.

Stable isotope research pool inventory

International Nuclear Information System (INIS)

1982-01-01

This report contains a listing of electromagnetically separated stable isotopes which are available for distribution within the United States for nondestructive research use from the Oak Ridge National Laboratory on a loan basis. This inventory includes all samples of stable isotopes in the Material Research Collection and does not designate whether a sample is out on loan or in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

Inverse relations in the patterns of muscle and center of pressure dynamics during standing still and movement postures.

Science.gov (United States)

Morrison, S; Hong, S L; Newell, K M

2007-08-01

The aim of this study was to investigate the postural center of pressure (COP) and surface muscle (EMG) dynamics of young adult participants under conditions where they were required to voluntarily produce random and regular sway motions in contrast to that of standing still. Frequency, amplitude and regularity measures of the COP excursion and EMG activity were assessed, as were measures of the coupling relations between the COP and EMG outputs. The results demonstrated that, even when standing still, there was a high degree of regularity in the COP output, with little difference in the modal frequency dynamics between standing still and preferred motion. Only during random conditions was a significantly greater degree of irregularity observed in the COP measures. The random-like movements were also characterized by a decrease in the level of synchrony between COP motion on the anterior-posterior (AP) and medio-lateral (ML) axes. In contrast, at muscle level, the random task resulted in the highest level of regularity (decreased ApEn) for the EMG output for soleus and tibialis anterior. The ability of individuals to produce a random motion was achieved through the decoupling of the COP motion in each dimension. This decoupling strategy was reflected by increased regularity of the EMG output as opposed to any significant change in the synchrony in the firing patterns of the muscles examined. Increased regularity across the individual muscles was accompanied by increased irregularity in COP dynamics, which can be characterized as a complexity tradeoff. Collectively, these findings support the view that the dynamics of muscle firing patterns does not necessarily map directly to the dynamics at the movement task level and vice versa.

Characterizing HIV epidemiology in stable couples in Cambodia, the Dominican Republic, Haiti, and India.

Science.gov (United States)

Chemaitelly, H; Abu-Raddad, L J

2016-01-01

Using a set of statistical methods and HIV mathematical models applied on nationally representative Demographic and Health Survey data, we characterized HIV serodiscordancy patterns and HIV transmission dynamics in stable couples (SCs) in four countries: Cambodia, the Dominican Republic, Haiti, and India. The majority of SCs affected by HIV were serodiscordant, and about a third of HIV-infected persons had uninfected partners. Overall, nearly two-thirds of HIV infections occurred in individuals in SCs, but only about half of these infections were due to transmissions within serodiscordant couples. The majority of HIV incidence in the population occurred through extra-partner encounters in SCs. There is similarity in HIV epidemiology in SCs between these countries and countries in sub-Saharan Africa, despite the difference in scale of epidemics. It appears that HIV epidemiology in SCs may share similar patterns globally, possibly because it is a natural 'spillover' effect of HIV dynamics in high-risk populations.

Exact simulation of max-stable processes.

Science.gov (United States)

Dombry, Clément; Engelke, Sebastian; Oesting, Marco

2016-06-01

Max-stable processes play an important role as models for spatial extreme events. Their complex structure as the pointwise maximum over an infinite number of random functions makes their simulation difficult. Algorithms based on finite approximations are often inexact and computationally inefficient. We present a new algorithm for exact simulation of a max-stable process at a finite number of locations. It relies on the idea of simulating only the extremal functions, that is, those functions in the construction of a max-stable process that effectively contribute to the pointwise maximum. We further generalize the algorithm by Dieker & Mikosch (2015) for Brown-Resnick processes and use it for exact simulation via the spectral measure. We study the complexity of both algorithms, prove that our new approach via extremal functions is always more efficient, and provide closed-form expressions for their implementation that cover most popular models for max-stable processes and multivariate extreme value distributions. For simulation on dense grids, an adaptive design of the extremal function algorithm is proposed.

Cell patterning through inkjet printing of one cell per droplet

International Nuclear Information System (INIS)

Yamaguchi, Shuichi; Akiyama, Yoshitake; Morishima, Keisuke; Ueno, Akira

2012-01-01

The inkjet ejection technology used in printers has been adopted and research has been conducted on manufacturing artificial tissue by patterning cells through micronozzle ejection of small droplets containing multiple cells. However, stable injection of cells has proven difficult, owing to the frequent occurrence of nozzle clogging. In this paper, a piezoelectric inkjet head constructed with a glass capillary that enabled viewing of the nozzle section was developed, the movement of cells ejected from the nozzle tip was analyzed, and a method for stably ejecting cells was verified. A pull–push ejection method was compared with a push–pull ejection method regarding the voltage waveform applied to the piezoelectric element of the head. The push–pull method was found to be more suitable for stable ejection. Further, ejection of one cell per droplet was realized by detecting the position of the cell in the nozzle section and utilizing these position data. Thus, a method for more precise patterning of viable cells at desired position and number was established. This method is very useful and promising not only for biofabrication, 3D tissue construction, cell printing, but also for a number of biomedical application, such as bioMEMS, lab on a chip research field. (paper)

Creation of wettability contrast patterns on metallic surfaces via pen drawn masks

Science.gov (United States)

Choi, Won Tae; Yang, Xiaolong; Breedveld, Victor; Hess, Dennis W.

2017-12-01

Micropatterned surfaces with wettability contrast have attracted considerable attention due to potential applications in 2D microfluidics, bioassays, and water harvesting. A simple method to develop wettability contrast patterns on metallic surfaces by using a commercial marker is described. A marker-drawn ink pattern on a copper surface displays chemical resistance to an aqueous solution of sodium bicarbonate and ammonium persulfate, thereby enabling selective nanowire growth in areas where ink is absent. Subsequent ink removal by an organic solvent followed by fluorocarbon film deposition yields a stable hydrophobic/super-hydrophobic patterned copper surface. Using this approach, hydrophobic dot and line patterns were constructed. The adhesion force of water droplets to the dots was controlled by adjusting pattern size, thus enabling controlled droplet transfer between two surfaces. Anisotropy of water droplet adhesion to line patterns can serve as a basis for directional control of water droplet motion. This general approach has also been employed to generate wettability contrast on aluminum surfaces, thereby demonstrating versatility. Due to its simplicity, low cost, and virtual independence of solid surface material, ink marker pens can be employed to create wettability patterns for a variety of applications, in fields as diverse as biomedicine and energy.

Mechanisms of postural control in alcoholic men and women: biomechanical analysis of musculoskeletal coordination during quiet standing.

Science.gov (United States)

Sullivan, Edith V; Rose, Jessica; Pfefferbaum, Adolf

2010-03-01

Excessive sway during quiet standing is a common sequela of chronic alcoholism even with prolonged sobriety. Whether alcoholic men and women who have remained abstinent from alcohol for weeks to months differ from each other in the degree of residual postural instability and biomechanical control mechanisms has not been directly tested. We used a force platform to characterize center-of-pressure biomechanical features of postural sway, with and without stabilizing conditions from touch, vision, and stance, in 34 alcoholic men, 15 alcoholic women, 22 control men, and 29 control women. Groups were matched in age (49.4 years), general intelligence, socioeconomic status, and handedness. Each alcoholic group was sober for an average of 75 days. Analysis of postural sway when using all 3 stabilizing conditions versus none revealed diagnosis and sex differences in ability to balance. Alcoholics had significantly longer sway paths, especially in the anterior-posterior direction, than controls when maintaining erect posture without balance aids. With stabilizing conditions the sway paths of all groups shortened significantly, especially those of alcoholic men, who demonstrated a 3.1-fold improvement in sway path difference between the easiest and most challenging conditions; the remaining 3 groups, each showed a approximately 2.4-fold improvement. Application of a mechanical model to partition sway paths into open-loop and closed-loop postural control systems revealed that the sway paths of the alcoholic men but not alcoholic women were characterized by greater short-term (open-loop) diffusion coefficients without aids, often associated with muscle stiffening response. With stabilizing factors, all 4 groups showed similar long-term (closed loop) postural control. Correlations between cognitive abilities and closed-loop sway indices were more robust in alcoholic men than alcoholic women. Reduction in sway and closed-loop activity during quiet standing with stabilizing

Stable Water Use Efficiency under Climate Change of Three Sympatric Conifer Species at the Alpine Treeline.

Science.gov (United States)

Wieser, Gerhard; Oberhuber, Walter; Gruber, Andreas; Leo, Marco; Matyssek, Rainer; Grams, Thorsten Erhard Edgar

2016-01-01

The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies, and Larix decidua trees from 1975 to 2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE) of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ(13)C and Δ(18)O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI) suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species.

The secret gardener: vegetation and the emergence of biogeomorphic patterns in tidal environments.

Science.gov (United States)

Da Lio, Cristina; D'Alpaos, Andrea; Marani, Marco

2013-01-01

The presence and continued existence of tidal morphologies, and in particular of salt marshes, is intimately connected with biological activity, especially with the presence of halophytic vegetation. Here, we review recent contributions to tidal biogeomorphology and identify the presence of multiple competing stable states arising from a two-way feedback between biomass productivity and topographic elevation. Hence, through the analysis of previous and new results on spatially extended biogeomorphological systems, we show that multiple stable states constitute a unifying framework explaining emerging patterns in tidal environments from the local to the system scale. Furthermore, in contrast with traditional views we propose that biota in tidal environments is not just passively adapting to morphological features prescribed by sediment transport, but rather it is 'The Secret Gardener', fundamentally constructing the tidal landscape. The proposed framework allows to identify the observable signature of the biogeomorphic feedbacks underlying tidal landscapes and to explore the response and resilience of tidal biogeomorphic patterns to variations in the forcings, such as the rate of relative sea-level rise.

Stable isotope mass spectrometry in petroleum exploration

International Nuclear Information System (INIS)

Mathur, Manju

1997-01-01

The stable isotope mass spectrometry plays an important role to evaluate the stable isotopic composition of hydrocarbons. The isotopic ratios of certain elements in petroleum samples reflect certain characteristics which are useful for petroleum exploration

Arrival and Departure Patterns of Public Sector Employees before and after Implementation of Flexitime.

Science.gov (United States)

Ronen, Simcha

1981-01-01

Examined the effects of a flexible working hours schedule on the arrival and departure times of 162 public sector employees. Results indicated that workers, when scheduling their own workday, deviate only moderately from their preflexitime arrival/departure times; and they tend to develop relatively stable arrival/departure patterns. (Author/RC)

Patterns in blood pressure medication use in US incident dialysis patients over the first 6 months

NARCIS (Netherlands)

St Peter, Wendy L.; Sozio, Stephen M.; Shafi, Tariq; Ephraim, Patti L.; Luly, Jason; McDermott, Aidan; Bandeen-Roche, Karen; Meyer, Klemens B.; Crews, Deidra C.; Scialla, Julia J.; Miskulin, Dana C.; Tangri, Navdeep; Jaar, Bernard G.; Michels, Wieneke M.; Wu, Albert W.; Boulware, L. Ebony

2013-01-01

Several observational studies have evaluated the effect of a single exposure window with blood pressure (BP) medications on outcomes in incident dialysis patients, but whether BP medication prescription patterns remain stable or a single exposure window design is adequate to evaluate effect on

Balance and Gait Represent Independent Domains of Mobility in Parkinson Disease

Science.gov (United States)

Horak, Fay B.; Carlson-Kuhta, Patricia; Nutt, John G.; Salarian, Arash

2016-01-01

Background The Instrumented Stand and Walk (ISAW) test, which includes 30 seconds of stance, step initiation, gait, and turning, results in many objective balance and gait metrics from body-worn inertial sensors. However, it is not clear which metrics provide independent information about mobility. Objective It was hypothesized that balance and gait represent several independent domains of mobility and that not all domains would be abnormal in individuals with Parkinson disease (PD) or would change with levodopa therapy. Design This was a cross-sectional study. Methods A factor analysis approach was used to identify independent measures of mobility extracted from the ISAW in 100 participants with PD and 21 control participants. First, a covariance analysis showed that postural sway measures were independent of gait measures. Then, the factor analysis revealed 6 independent factors (mobility domains: sway area, sway frequency, arm swing asymmetry, trunk motion during gait, gait speed, and cadence) that accounted for 87% of the variance of performance across participants. Results Sway area, gait speed, and trunk motion differed between the PD group in the off-levodopa state and the control group, but sway frequency (but not sway area) differed between the PD group in the off-levodopa state and the control group. Four of the 6 factors changed significantly with levodopa (off to on): sway area, sway frequency, trunk motion during gait, and cadence. When participants were on levodopa, the sway area increased compared with off levodopa, becoming more abnormal, whereas the other 3 significant metrics moved toward, but did not reach, the healthy control values. Limitations Exploratory factor analysis was limited to the PD population. Conclusions The different sensitivity various balance and gait domains to PD and to levodopa also support neural control of at least 6 independent mobility domains, each of which warrants clinical assessment for impairments in mobility. PMID

Consistent habitat segregation between sexes in the spider crabs Maja brachydactyla and Maja squinado (Brachyura, as revealed by stable isotopes

Directory of Open Access Journals (Sweden)

Guillermo Guerao

2016-03-01

Full Text Available Differences in the resource use patterns of males and females of the spider crab species Maja brachydactyla Balss, 1922 and M. squinado (Herbst, 1788 from several geographic areas (three in the Atlantic and two in the Mediterranean were studied through the analysis of stable isotopes of carbon and nitrogen in the exoskeleton of post-pubertal (adult specimens. Results confirmed that males and females from the same population usually did not differ in δ15N values and hence foraged at the same trophic level. In contrast, females were usually enriched in 13C as compared with males from the same population, thus suggesting that females use shallower habitats than males before the terminal moult. The results reported here also indicate that stable isotop.

Dynamic postural stability during advancing pregnancy.

Science.gov (United States)

McCrory, J L; Chambers, A J; Daftary, A; Redfern, M S

2010-08-26

Pregnant women are at an increased risk of experiencing a fall. Numerous anatomical, physiological, and hormonal alterations occur during pregnancy, but the influence of these factors on dynamic postural stability has not been explored. The purpose of this study was to examine dynamic postural stability in pregnant women during their second and third trimesters as well as in a group of non-pregnant control women. Eighty-one women (41 pregnant, 40 controls) participated stood on a force plate that translated anteroposteriorly at small, medium, and large magnitudes. Reaction time and center of pressure (COP) movement during the translations were analyzed. Trimester, perturbation direction, and perturbation magnitude were the independent variables in a mixed-model analysis of variance on each of the following dependent variables: reaction time, initial sway, total sway, and sway velocity. Reaction time to the perturbation was not significantly different between the groups. Initial sway, total sway, and sway velocity were significantly less during the third trimester than during the second trimester and when compared to the non-pregnant controls (Ppostural stability. 2010 Elsevier Ltd. All rights reserved.

Patterns and stability of a whirlpool flow

Energy Technology Data Exchange (ETDEWEB)

Carrión, Luis [Universidad de las Fuerzas Armadas-ESPE, Av. Gral. Rumiñahui s/n Sangolquí 171103 (Ecuador); Herrada, Miguel A; María López-Herrera, José [E.S.I, Universidad de Sevilla, Camino de los Descubrimientos s/n 41092 (Spain); Shtern, Vladimir N [Shtern Research and Consulting, Houston, Texas 77096, United States of America (United States)

2017-04-15

This numerical study reveals stable multi-eddy patterns of a steady axisymmetric air–water flow driven by the rotating bottom disk in a vertical sealed cylindrical container. As rotation strength Re increases, eddies emerge, coalesce, separate, and disappear in both air and water. The topological scenario varies with water volume fraction H{sub w} according to the results obtained for H{sub w}  = 0.3, 0.5, and 0.8. Interesting features are: (a) zipper-like chains of air and water eddies forming as the interface bends and (b) bubble-ring air eddies existing in the Re ranges specified in the paper. The stability analysis, performed with the help of a novel efficient technique for two-fluid flows, shows that these multi-eddy motions are stable. The shear-layer instability develops as the interface approaches either the top or bottom of the container and some eddies vanish. The physical reasoning behind the eddy formation and the flow instability is provided. The results are of fundamental interest and can have applications in bioreactors. (paper)

Multi-stable perception balances stability and sensitivity

Directory of Open Access Journals (Sweden)

Alexander ePastukhov

2013-03-01

Full Text Available We report that multi-stable perception operates in a consistent, dynamical regime, balancing the conflicting goals of stability and sensitivity. When a multi-stable visual display is viewed continuously, its phenomenal appearance reverses spontaneously at irregular intervals. We characterized the perceptual dynamics of individual observers in terms of four statistical measures: the distribution of dominance times (mean and variance and the novel, subtle dependence on prior history (correlation and time-constant.The dynamics of multi-stable perception is known to reflect several stabilizing and destabilizing factors. Phenomenologically, its main aspects are captured by a simplistic computational model with competition, adaptation, and noise. We identified small parameter volumes (~3% of the possible volume in which the model reproduced both dominance distribution and history-dependence of each observer. For 21 of 24 data sets, the identified volumes clustered tightly (~15% of the possible volume, revealing a consistent `operating regime' of multi-stable perception. The `operating regime' turned out to be marginally stable or, equivalently, near the brink of an oscillatory instability. The chance probability of the observed clustering was <0.02.To understand the functional significance of this empirical `operating regime', we compared it to the theoretical `sweet spot' of the model. We computed this `sweet spot' as the intersection of the parameter volumes in which the model produced stable perceptual outcomes and in which it was sensitive to input modulations. Remarkably, the empirical `operating regime' proved to be largely coextensive with the theoretical `sweet spot'. This demonstrated that perceptual dynamics was not merely consistent but also functionally optimized (in that it balances stability with sensitivity. Our results imply that multi-stable perception is not a laboratory curiosity, but reflects a functional optimization of perceptual

Numerical simulations of cellular detonation diffraction in a stable gaseous mixture

Directory of Open Access Journals (Sweden)

Jian Li

2016-09-01

Full Text Available In this paper, the diffraction phenomenon of gaseous cellular detonations emerging from a confined tube into a sudden open space is simulated using the reactive Euler equations with a two-step Arrhenius chemistry model. Both two-dimensional and axisymmetric configurations are used for modeling cylindrical and spherical expansions, respectively. The chemical parameters are chosen for a stable gaseous explosive mixture in which the cellular detonation structure is highly regular. Adaptive mesh refinement (AMR is used to resolve the detonation wave structure and its evolution during the transmission. The numerical results show that the critical channel width and critical diameter over the detonation cell size are about 13±1 and 25±1, respectively. These numerical findings are comparable with the experimental observation and confirm again that the critical channel width and critical diameter differ essentially by a factor close to 2, equal to the geometrical scaling based on front curvature theory. Unlike unstable mixtures where instabilities manifested in the detonation front structure play a significant role during the transmission, the present numerical results and the observed geometrical scaling provide again evidence that the failure of detonation diffraction in stable mixtures with a regular detonation cellular pattern is dominantly caused by the global curvature due to the wave divergence resulting in the global decoupling of the reaction zone with the expanding shock front.

Analysing Stable Time Series

National Research Council Canada - National Science Library

Adler, Robert

1997-01-01

We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...

Tukey max-stable processes for spatial extremes

KAUST Repository

Xu, Ganggang; Genton, Marc G.

2016-01-01

We propose a new type of max-stable process that we call the Tukey max-stable process for spatial extremes. It brings additional flexibility to modeling dependence structures among spatial extremes. The statistical properties of the Tukey max

Seasonal variations of stable isotope in precipitation and moisture transport at Yushu,eastern Tibetan Plateau

Institute of Scientific and Technical Information of China (English)

2008-01-01

Precipitation δ 18O at Yushu, eastern Tibetan Plateau, shows strong fluctuation and lack of clear seasonality. The seasonal pattern of precipitation stable isotope at Yushu is apparently different from either that of the southwest monsoon region to the south or that of the inland region to the north. This different seasonal pattern probably reflects the shift of different moisture sources. In this paper, we present the spatial comparison of the seasonal patterns of precipitation δ 18O, and calculate the moisture transport flux by using the NCAR/NCEP reanalysis data. This allows us to discuss the relation between moisture transport flux and precipitation δ 18O. This study shows that both the southwest monsoon from south and inland air mass transport from north affected the seasonal precipitation δ 18O at Yushu, eastern Tibetan Plateau. Southwest monsoon brings the main part of the moisture, but southwest transport flux is weaker than in the southern part of the Tibetan Plateau. However, contribution of the inland moisture from north or local evaporation moisture is enhanced. The combined effect is the strong fluctuation of summer precipitation δ 18O at Yushu and comparatively poor seasonality.

How Life History Can Sway the Fixation Probability of Mutants

Science.gov (United States)

Li, Xiang-Yi; Kurokawa, Shun; Giaimo, Stefano; Traulsen, Arne

2016-01-01

In this work, we study the effects of demographic structure on evolutionary dynamics when selection acts on reproduction, survival, or both. In contrast to the previously discovered pattern that the fixation probability of a neutral mutant decreases while the population becomes younger, we show that a mutant with a constant selective advantage may have a maximum or a minimum of the fixation probability in populations with an intermediate fraction of young individuals. This highlights the importance of life history and demographic structure in studying evolutionary dynamics. We also illustrate the fundamental differences between selection on reproduction and selection on survival when age structure is present. In addition, we evaluate the relative importance of size and structure of the population in determining the fixation probability of the mutant. Our work lays the foundation for also studying density- and frequency-dependent effects in populations when demographic structures cannot be neglected. PMID:27129737

Patterns of patterns of synchronization: Noise induced attractor switching in rings of coupled nonlinear oscillators

Energy Technology Data Exchange (ETDEWEB)

Emenheiser, Jeffrey [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Physics, University of California, Davis, California 95616 (United States); Chapman, Airlie; Mesbahi, Mehran [William E. Boeing Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Pósfai, Márton [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Crutchfield, James P. [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Physics, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Santa Fe Institute, Santa Fe, New Mexico 87501 (United States); D' Souza, Raissa M. [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Santa Fe Institute, Santa Fe, New Mexico 87501 (United States); Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States)

2016-09-15

Following the long-lived qualitative-dynamics tradition of explaining behavior in complex systems via the architecture of their attractors and basins, we investigate the patterns of switching between distinct trajectories in a network of synchronized oscillators. Our system, consisting of nonlinear amplitude-phase oscillators arranged in a ring topology with reactive nearest-neighbor coupling, is simple and connects directly to experimental realizations. We seek to understand how the multiple stable synchronized states connect to each other in state space by applying Gaussian white noise to each of the oscillators' phases. To do this, we first analytically identify a set of locally stable limit cycles at any given coupling strength. For each of these attracting states, we analyze the effect of weak noise via the covariance matrix of deviations around those attractors. We then explore the noise-induced attractor switching behavior via numerical investigations. For a ring of three oscillators, we find that an attractor-switching event is always accompanied by the crossing of two adjacent oscillators' phases. For larger numbers of oscillators, we find that the distribution of times required to stochastically leave a given state falls off exponentially, and we build an attractor switching network out of the destination states as a coarse-grained description of the high-dimensional attractor-basin architecture.

Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes.

Science.gov (United States)

Vizza, Carmella; Sanderson, Beth L; Coe, Holly J; Chaloner, Dominic T

2017-03-01

Stable isotope ratios (δ 13 C and δ 15 N) have been used extensively to trace nutrients from Pacific salmon, but salmon transfer more than carbon and nitrogen to stream ecosystems, such as phosphorus, minerals, proteins, and lipids. To examine the importance of these nutrients, metrics other than isotopes need to be considered, particularly when so few studies have made direct links between these nutrients and how they affect riparian organisms. Our study specifically examined δ 13 C and δ 15 N of riparian organisms from salmon and non-salmon streams in Idaho, USA, at different distances from the streams, and examined whether the quality of riparian plants and the body condition of invertebrates varied with access to these nutrients. Overall, quality and condition metrics did not mirror stable isotope patterns. Most notably, all riparian organisms exhibited elevated δ 15 N in salmon streams, but also with proximity to both stream types suggesting that both salmon and landscape factors may affect δ 15 N. The amount of nitrogen incorporated from Pacific salmon was low for all organisms (1950s. In addition, our results support those of other studies that have cautioned that inferences from natural abundance isotope data, particularly in conjunction with mixing models for salmon-derived nutrient percentage estimates, may be confounded by biogeochemical transformations of nitrogen, physiological processes, and even historical legacies of nitrogen sources. Critically, studies should move beyond simply describing isotopic patterns to focusing on the consequences of salmon-derived nutrients by quantifying the condition and fitness of organisms putatively using those resources.

Wetland Loss Patterns and Inundation-Productivity Relationships Prognosticate Widespread Salt Marsh Loss for Southern New England

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Tidal salt marsh is a key defense against, yet is especially vulnerable to, the effects of accelerated sea level rise. To determine whether salt marshes in southern New England will be stable given increasing inundation over the coming decades, we examined current loss patterns, ...

A study of distribution, sex differences and stability of lip print patterns in an Indian population.

Science.gov (United States)

Kapoor, Neeti; Badiye, Ashish

2017-09-01

Lip prints are very useful in forensic investigations. The objective of this study is to determine predominant lip print pattern found among a central Indian population, to evaluate whether any sex difference exists and to study the permanence of the pattern over a 6 month duration. This study included 200 healthy adult subjects comprising of 100 males and 100 females in the age group of 18-25 years. A convenient and easier method of data collection i.e., digital photography was used instead of the traditional lipstick methods. Lip prints were then divided into four quadrants and recognized as per Suzuki and Tsuchihashi's classification. Type I (30.63%) was found to be most predominant overall in the Marathi population. Type I (29.75%) and Type III (35.75%) were found most prevalent in males and females respectively. Applying the Chi-Square test, statistically significant differences ( p  < 0.05) were observed between male and female lip print patterns in each of the quadrants individually and all quadrants taken together. The lip print patterns remained stable over a period of six-months. Being stable and with significant sex differences, lip prints can be effectively used as an important tool in forensic investigations for individualization as well as identification of sex of the donor, thus, narrowing down the scope of investigation to almost half.

Stable isotope studies

International Nuclear Information System (INIS)

Ishida, T.

1992-01-01

The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

Electromiography comparison of distal and proximal lower limb muscle activity patterns during external perturbation in subjects with and without functional ankle instability.

Science.gov (United States)

Kazemi, Khadijeh; Arab, Amir Massoud; Abdollahi, Iraj; López-López, Daniel; Calvo-Lobo, César

2017-10-01

Ankle sprain is one of the most common injuries among athletes and the general population. Most ankle injuries commonly affect the lateral ligament complex. Changes in postural sway and hip abductor muscle strength may be generated after inversion ankle sprain. Therefore, the consequences of ankle injury may affect proximal structures of the lower limb. The aim is to describe and compare the activity patterns of distal and proximal lower limb muscles following external perturbation in individuals with and without functional ankle instability. The sample consisted of 16 women with functional ankle instability and 18 healthy women were recruited to participate in this research. The external perturbation via body jacket using surface electromyography, amplitude and onset of muscle activity of gluteus maximums, gluteus medius, tibialis anterior, and peroneus longus was recorded and analyzed during external perturbation. There were differences between the onset of muscles activity due to perturbation direction in the two groups (healthy and functional ankle instability). In the healthy group, there were statistically significant differences in amplitude of proximal muscle activity with distal muscle activity during front perturbation with eyes open and closed. In the functional ankle instability group; there were statistically significant differences in amplitude of proximal muscle activity with distal muscle activity during perturbation of the front and back with eyes open. There were statistically significant differences in the onset of muscle activity and amplitude of muscle activity, with-in and between groups (Pankle instability, activation patterns of the lower limb proximal muscles may be altered. Copyright © 2017 Elsevier B.V. All rights reserved.

Late Glacial Tropical Savannas in Sundaland Inferred From Stable Carbon Isotope Records of Cave Guano

Science.gov (United States)

Wurster, C. M.; Bird, M. I.; Bull, I.; Dungait, J.; Bryant, C. L.; Ertunç, T.; Hunt, C.; Lewis, H. A.; Paz, V.

2008-12-01

During the Last Glacial Period (LGP), reduced global sea level exposed the continental shelf south of Thailand to Sumatra, Java, and Borneo to form the contiguous continent of Sundaland. However, the type and extent of vegetation that existed on much of this exposed landmass during the LGP remains speculative. Extensive bird and bat guano deposits in caves throughout this region span beyond 40,000 yr BP, and contain a wealth of untapped stratigraphic palaeoenvironmental information. Stable carbon isotope ratios of insectivorous bird and bat guano contain a reliable record of the animal's diet and, through non-specific insect predation, reflect the relative abundance of major physiological pathways in plants. Various physiological pathways of carbon fixation in plants yield differing stable carbon isotope ratios. Stable carbon isotope values of C3 plants are lower than C4 vegetation due to different enzymatic discriminations of the heavy isotope through the carbon fixing pathways. In tropical locales, grasses nearly always follow the C4 photosynthetic pathway, whereas tropical rainforest uses C3 photosynthesis, providing a proxy for vegetation and therefore climate change in the past. Here we discuss four guano stable-isotope records, based on insect cuticle and n-alkane analysis, supplemented by pollen analysis. All sites suggest a C3 dominated ecosystem for the Holocene, consistent with the wet tropical forest vegetation present at all locations. Two sites from Palawan Island, Philippines, record stable carbon isotope values of guano that document a drastic change from C3 (forest) to C4 (savanna) dominated ecosystems during the Last Glacial Maximum (LGM). A third location, at Niah Great Cave, Malaysia, indicates C3-dominant vegetation throughout the record, but does display variation in stable carbon isotope values likely linked to humidity changes. A fourth location, Batu Caves in Peninsular Malaysia, also indicates open vegetation during the LGM. Vegetation

Wideband quin-stable energy harvesting via combined nonlinearity

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Chen Wang

2017-04-01

Full Text Available In this work, we propose a wideband quintuple-well potential piezoelectric-based vibration energy harvester using a combined nonlinearity: the magnetic nonlinearity induced by magnetic force and the piecewise-linearity produced by mechanical impact. With extra stable states compared to other multi-stable harvesters, the quin-stable harvester can distribute its potential energy more uniformly, which provides shallower potential wells and results in lower excitation threshold for interwell motion. The mathematical model of this quin-stable harvester is derived and its equivalent piecewise-nonlinear restoring force is measured in the experiment and identified as piecewise polynomials. Numerical simulations and experimental verifications are performed in different levels of sinusoid excitation ranging from 1 to 25 Hz. The results demonstrate that, with lower potential barriers compared with tri-stable counterpart, the quin-stable arrangement can escape potential wells more easily for doing high-energy interwell motion over a wider band of frequencies. Moreover, by utilizing the mechanical stoppers, this harvester can produce significant output voltage under small tip deflections, which results in a high power density and is especially suitable for a compact MEMS approach.

Effects of a flat prosthetic foot rocker section on balance and mobility.

Science.gov (United States)

Hansen, Andrew; Nickel, Eric; Medvec, Joseph; Brielmaier, Steven; Pike, Alvin; Weber, Marilyn

2014-01-01

Previous studies have shown that the effective rocker shape of the physiologic ankle-foot system during standing and fore-aft swaying is much flatter than that used during walking, which indicates a more stable base of support for the standing/swaying activity. Previous work suggests that flat regions within the effective rocker shapes of prosthetic ankle-foot systems could provide enhanced stability for standing balance tasks. An experimental prosthetic foot was altered to provide three different flat region lengths within its effective rocker shape. It was hypothesized that longer flat regions of the effective rocker shape would lead to improved standing balance outcomes and reduced walking performance for unilateral transtibial prosthesis users. However, no significant changes were seen in the balance and mobility outcomes of 12 unilateral transtibial prosthesis users when using the three prosthetic foot conditions. Subjects in the study significantly preferred prosthetic feet with relatively low to moderate flat regions over those with long flat regions. All the subjects without loss of light touch or vibratory sensation selected the prosthetic foot with the shortest flat region. More work is needed to investigate the effects of prosthetic foot properties on balance and mobility of prosthesis users.

Spongiosa Primary Development: A Biochemical Hypothesis by Turing Patterns Formations

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Oscar Rodrigo López-Vaca

2012-01-01

Full Text Available We propose a biochemical model describing the formation of primary spongiosa architecture through a bioregulatory model by metalloproteinase 13 (MMP13 and vascular endothelial growth factor (VEGF. It is assumed that MMP13 regulates cartilage degradation and the VEGF allows vascularization and advances in the ossification front through the presence of osteoblasts. The coupling of this set of molecules is represented by reaction-diffusion equations with parameters in the Turing space, creating a stable spatiotemporal pattern that leads to the formation of the trabeculae present in the spongy tissue. Experimental evidence has shown that the MMP13 regulates VEGF formation, and it is assumed that VEGF negatively regulates MMP13 formation. Thus, the patterns obtained by ossification may represent the primary spongiosa formation during endochondral ossification. Moreover, for the numerical solution, we used the finite element method with the Newton-Raphson method to approximate partial differential nonlinear equations. Ossification patterns obtained may represent the primary spongiosa formation during endochondral ossification.

Age-related patterns of drug use initiation among polydrug using regular psychostimulant users.

Science.gov (United States)

Darke, Shane; Kaye, Sharlene; Torok, Michelle

2012-09-01

To determine age-related patterns of drug use initiation, drug sequencing and treatment entry among regular psychostimulant users. Cross-sectional study of 269 regular psychostimulant users, administered a structured interview examining onset of use for major licit and illicit drugs. The mean age at first intoxication was not associated with age or gender. In contrast, younger age was associated with earlier ages of onset for all of the illicit drug classes. Each additional year of age was associated with a 4 month increase in onset age for methamphetamine, and 3 months for heroin. By the age of 17, those born prior to 1961 had, on average, used only tobacco and alcohol, whereas those born between 1986 and 1990 had used nine different drug classes. The period between initial use and the transition to regular use, however, was stable. Age was also negatively correlated with both age at initial injection and regular injecting. Onset sequences, however, remained stable. Consistent with the age-related patterns of drug use, each additional year of age associated with a 0.47 year increase in the age at first treatment. While the age at first intoxication appeared stable, the trajectory through illicit drug use was substantially truncated. The data indicate that, at least among those who progress to regular illicit drug use, younger users are likely to be exposed to far broader polydrug use in their teens than has previously been the case. © 2012 Australasian Professional Society on Alcohol and other Drugs.

Analog electronic model of the lobster pyloric central pattern generator

Energy Technology Data Exchange (ETDEWEB)

Volkovskii, A [Institute for Nonlinear Science, University of California San Diego, CA (United States); Brugioni, S [Institute for Nonlinear Science, University of California San Diego, CA (United States); Istituto Nazionale di Ottica Applicata Largo E. Fermi 6 50125 Florence (Italy); Levi, R [Institute for Nonlinear Science, University of California San Diego, CA (United States); Rabinovich, M [Institute for Nonlinear Science, University of California San Diego, CA (United States); Selverston, A [Institute for Nonlinear Science, University of California San Diego, CA (United States); Abarbane, H D I [Institute for Nonlinear Science, University of California San Diego, CA (United States)

2005-01-01

An electronic circuit intended to simulate the nonlinear dynamics of a simplified 3-cell model of the pyloric central pattern generator in California spiny lobster stomato gastric ganglion is presented. The model employs the synaptic phase locked loop (SPLL) concept where the frequency of oscillations of a postsynaptic cell is mainly controlled by the synaptic current which depends on the phase shift between the oscillations. The theoretical study showed that the system has a stable steady state with correct phase shifts between the oscillations and that this regime is stable when the frequency of the pacemaker cell is varied over a wide range. The main bifurcations in the system were studied analytically, in computer simulations, and in experiments with the electronic circuit. The experimental measurements are in good agreement with the expectations of the theoretical model.

Sense of Humor, Stable Affect, and Psychological Well-Being

Directory of Open Access Journals (Sweden)

Arnie Cann

2014-08-01

Full Text Available A good sense of humor has been implicated as a quality that could contribute to psychological well-being. The mechanisms through which sense of humor might operate include helping to reappraise threats, serving as a character strength, or facilitating happiness. The current research attempts to integrate these possibilities by examining whether a good sense of humor might operate globally by helping to maintain a more stable positive affect. Stable positive affect has been shown to facilitate more effective problem solving and to build resilience. However, not all humor is adaptive humor, so we also examine the roles that different styles of humor use might play. Individual differences in humor styles were used to predict stable levels of affect. Then, in a longitudinal design, humor styles and stable affect were used to predict subsequent resilience and psychological health. The results indicated that stable affect was related to resilience and psychological well-being, and that a sense of humor that involves self-enhancing humor, humor based on maintaining a humorous perspective about one’s experiences, was positively related to stable positive affect, negatively related to stable negative affect, and was mediated through stable affect in influencing resilience, well-being and distress. Thus, while a good sense of humor can lead to greater resilience and better psychological health, the current results, focusing on stable affect, find only self-enhancing humor provides reliable benefits.

Applications of stable isotopes in clinical pharmacology

NARCIS (Netherlands)

Schellekens, Reinout C A; Stellaard, Frans; Woerdenbag, Herman J; Frijlink, Henderik W; Kosterink, Jos G W

2011-01-01

This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the

Which Diet-Related Behaviors in Childhood Influence a Healthier Dietary Pattern? From the Ewha Birth and Growth Cohort.

Science.gov (United States)

Lee, Hye Ah; Hwang, Hyo Jeong; Oh, Se Young; Park, Eun Ae; Cho, Su Jin; Kim, Hae Soon; Park, Hyesook

2016-12-23

This study was performed to examine how childhood dietary patterns change over the short term and which changes in diet-related behaviors influence later changes in individual dietary patterns. Using food frequency questionnaire data obtained from children at 7 and 9 years of age from the Ewha Birth and Growth Cohort, we examined dietary patterns by principal component analysis. We calculated the individual changes in dietary pattern scores. Changes in dietary habits such as eating a variety of food over two years were defined as "increased", "stable", or "decreased". The dietary patterns, termed "healthy intake", "animal food intake", and "snack intake", were similar at 7 and 9 years of age. These patterns explained 32.3% and 39.1% of total variation at the ages of 7 and 9 years, respectively. The tracking coefficient of snack intake had the highest coefficient (γ = 0.53) and that of animal food intake had the lowest (γ = 0.21). Intra-individual stability in dietary habits ranged from 0.23 to 0.47, based on the sex-adjusted weighted kappa values. Of the various behavioral factors, eating breakfast every day was most common in the "stable" group (83.1%), whereas consuming milk or dairy products every day was the least common (49.0%). Moreover, changes in behavior that improved the consumption of milk or dairy products or encouraged the consumption of vegetables with every meal had favorable effects on changes in healthy dietary pattern scores over two years. However, those with worsened habits, such as less food variety and more than two portions of fried or stir-fried food every week, had unfavorable effects on changes in healthy dietary pattern scores. Our results suggest that diet-related behaviors can change, even over a short period, and these changes can affect changes in dietary pattern.

Detonation of Meta-stable Clusters

Energy Technology Data Exchange (ETDEWEB)

Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.

2008-05-31

We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

Perspective: Highly stable vapor-deposited glasses

Science.gov (United States)

Ediger, M. D.

2017-12-01

This article describes recent progress in understanding highly stable glasses prepared by physical vapor deposition and provides perspective on further research directions for the field. For a given molecule, vapor-deposited glasses can have higher density and lower enthalpy than any glass that can be prepared by the more traditional route of cooling a liquid, and such glasses also exhibit greatly enhanced kinetic stability. Because vapor-deposited glasses can approach the bottom of the amorphous part of the potential energy landscape, they provide insights into the properties expected for the "ideal glass." Connections between vapor-deposited glasses, liquid-cooled glasses, and deeply supercooled liquids are explored. The generality of stable glass formation for organic molecules is discussed along with the prospects for stable glasses of other types of materials.

Effects of euthanasia method on stable-carbon and stable-nitrogen isotope analysis for an ectothermic vertebrate.

Science.gov (United States)

Atwood, Meredith A

2013-04-30

Stable isotope analysis is a critical tool for understanding ecological food webs; however, results can be sensitive to sample preparation methods. To limit the possibility of sample contamination, freezing is commonly used to euthanize invertebrates and preserve non-lethal samples from vertebrates. For destructive sampling of vertebrates, more humane euthanasia methods are preferred to freezing and it is essential to evaluate how these euthanasia methods affect stable isotope results. Stable isotope ratios and elemental composition of carbon and nitrogen were used to evaluate whether the euthanasia method compromised the integrity of the sample for analysis. Specifically, the stable isotope and C:N ratios were compared for larval wood frogs (Rana sylvatica  =  Lithobates sylvaticus), an ectothermic vertebrate, that had been euthanized by freezing with four different humane euthanasia methods: CO2, benzocaine, MS-222 (tricaine methanesulfonate), and 70% ethanol. The euthanasia method was not related to the δ(13)C or δ(15)N values and the comparisons revealed no differences between freezing and any of the other treatments. However, there were slight (non-significant) differences in the isotope ratios of benzocaine and CO2 when each was compared with freezing. The elemental composition was altered by the euthanasia method employed. The percentage nitrogen was higher in CO2 treatments than in freezing, and similar (non-significant) trends were seen for ethanol treatments relative to freezing. The resulting C:N ratios were higher for benzocaine treatments than for both CO2 and ethanol. Similar (non-significant) trends suggested that the C:N ratios were also higher for animals euthanized by freezing than for both CO2 and ethanol euthanasia methods. The euthanasia method had a larger effect on elemental composition than stable isotope ratios. The percentage nitrogen and the subsequent C:N ratios were most affected by the CO2 and ethanol euthanasia methods, whereas

Development of postural control and maturation of sensory systems in children of different ages a cross-sectional study.

Science.gov (United States)

Sá, Cristina Dos Santos Cardoso de; Boffino, Catarina Costa; Ramos, Renato Teodoro; Tanaka, Clarice

To evaluate the stability, postural adjustments and contributions of sensory information for postural control in children. 40 boys and 40 girls were equally divided into groups of 5, 7, 9 and 12 years (G5, G7, G9 and G12). All children were submitted to dynamic posturography using a modified sensory organization test, using four sensory conditions: combining stable or sway referencing platform with eyes opened, or closed. The area and displacements of the center of pressure were used to determine stability, while the adjustments were used to measure the speed of the center of pressure displacements. These measurements were compared between groups and test conditions. Stability tends to increase with age and to decrease with sensory manipulation with significant differences between G5 and G7 in different measures. G7 differed from G12 under the conditions of stable and sway platform with eyes open. G9 did not differ from G12. Similar behavior was observed for adjustments, especially in anterior-posterior directions. Postural stability and adjustments were associated with age and were influenced by sensory manipulation. The ability to perform anterior-posterior adjustments was more evident and sensory maturation occurred firstly on the visual system, then proprioceptive system, and finally, the vestibular system, reaching functional maturity at nine years of age. Seven-year-olds seem to go through a period of differentiated singularity in postural control. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

Assessment of postural instability in patients with Parkinson's disease.

Science.gov (United States)

Błaszczyk, J W; Orawiec, R; Duda-Kłodowska, D; Opala, G

2007-10-01

Postural instability is one of the most disabling features of idiopathic Parkinson's disease (PD). In this study, we focused on postural instability as the main factor predisposing parkinsonians to falls. For this purpose, changes in sway characteristics during quiet stance due to visual feedback exclusion were studied. We searched for postural sway measures that could be potential discriminators for an increased fall risk. A group of 110 subjects: 55 parkinsonians (Hoehn and Yahr: 1-3), and 55 age-matched healthy volunteers participated in the experiment. Their spontaneous sway characteristics while standing quiet with eyes open and eyes closed were analyzed. We found that an increased mediolateral sway and sway area while standing with eyes closed are characteristic of parkinsonian postural instability and may serve to quantify well a tendency to fall. These sway indices significantly correlated with disease severity rated both by the Hoehn and Yahr scale as well as by the Motor Section of the UPDRS. A forward shift of a mean COP position in parkinsonians which reflects their flexed posture was also significantly greater to compare with the elderly subjects and exhibited a high sensitivity to visual conditions. Both groups of postural sway abnormalities identified here may be used as accessible and reliable measures which allow for quantitative assessment of postural instability in Parkinson's disease.

Myocardial perfusion SPECT in stable angina;Place de la scintigraphie myocardique dans l'angor stable

Energy Technology Data Exchange (ETDEWEB)

Jau, P.; Jacob, T. [HP Clairval, Service de medecine nucleaire, 13 - Marseille (France); Lecorff, G.; Bouvier, J.L.; Novella, P.; Bechet, V.; Pelet, V. [HP Clairval, Service de cardiologie, 13 - Marseille (France)

2010-03-15

We study the precise contribution of myocardial scintigraphy in the therapeutic management of stable coronary artery disease. Until recently, treatment was focused on revascularization, often by coronary angioplasty.Recent studies have challenged this practice by showing the absence of superiority of angioplasty compared to optimal medical therapy.The problem now is to define for each stable coronary artery disease, and individually, the best of both treatment options. In this spirit, the functional approach to coronary artery disease by myocardial perfusion scintigraphy is most interesting.The diagnostic performance, including sensitivity and negative predictive value, and the prognostic value of the technique are clearly established. Recent studies show that a therapeutic decision based on a functional approach to the patient is valid.We need to know this development in cardiology for best position in the multidisciplinary discussions, myocardial scintigraphy as a functional approach to stable coronary artery disease. (N.C.)

Stable Tetraquarks

Energy Technology Data Exchange (ETDEWEB)

Quigg, Chris [Fermilab

2018-04-13

For very heavy quarks, relations derived from heavy-quark symmetry imply novel narrow doubly heavy tetraquark states containing two heavy quarks and two light antiquarks. We predict that double-beauty states will be stable against strong decays, whereas the double-charm states and mixed beauty+charm states will dissociate into pairs of heavy-light mesons. Observing a new double-beauty state through its weak decays would establish the existence of tetraquarks and illuminate the role of heavy color-antitriplet diquarks as hadron constituents.

Development of stable isotope manufacturing in Russia

International Nuclear Information System (INIS)

Pokidychev, A.; Pokidycheva, M.

1999-01-01

For the past 25 years, Russia has relied heavily on the electromagnetic separation process for the production of middle and heavy mass stable isotopes. The separation of most light isotopes had been centered in Georgia which, after the collapse of the USSR, left Russia without this capability. In the mid-1970s, development of centrifuge technology for the separation of stable isotopes was begun. Alternative techniques such as laser separation, physical-chemical methods, and ion cyclotron resonance have also been investigated. Economic considerations have played a major role in the development and current status of the stable isotope enrichment capabilities of Russia

Finite element analysis of three patterns of internal fixation of fractures of the mandibular condyle.

Science.gov (United States)

Aquilina, Peter; Chamoli, Uphar; Parr, William C H; Clausen, Philip D; Wroe, Stephen

2013-06-01

The most stable pattern of internal fixation for fractures of the mandibular condyle is a matter for ongoing discussion. In this study we investigated the stability of three commonly used patterns of plate fixation, and constructed finite element models of a simulated mandibular condylar fracture. The completed models were heterogeneous in the distribution of bony material properties, contained about 1.2 million elements, and incorporated simulated jaw-adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. This model was considerably larger and more complex than previous finite element models that have been used to analyse the biomechanical behaviour of differing plating techniques. The use of two parallel 2.0 titanium miniplates gave a more stable configuration with lower mean element stresses and displacements over the use of a single miniplate. In addition, a parallel orientation of two miniplates resulted in lower stresses and displacements than did the use of two miniplates in an offset pattern. The use of two parallel titanium plates resulted in a superior biomechanical result as defined by mean element stresses and relative movement between the fractured fragments in these finite element models. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

[Current Treatment of Stable Angina].

Science.gov (United States)

Toggweiler, Stefan; Jamshidi, Peiman; Cuculi, Florim

2015-06-17

Current therapy for stable angina includes surgical and percutaneous revascularization, which has been improved tremendously over the last decades. Smoking cessation and regular exercise are the cornerstone for prevention of further cerebrovascular events. Medical treatment includes treatment of cardiovascular risk factors and antithrombotic management, which can be a challenge in some patients. Owing to the fact the coronary revascularization is readily accessible these days in many industrialized countries, the importance of antianginal therapy has decreased over the past years. This article presents a contemporary overview of the management of patients with stable angina in the year 2015.

Stable SU(5) monopoles with higher magnetic charge

International Nuclear Information System (INIS)

Miyamoto, S.; Sato, H.; Tomohiro, S.

1985-01-01

Taking into account the electroweak breaking effects, some multiply charged monopoles were shown to be stable by Gardner and Harvey. We give the explicit Ansa$uml: tze for finite-energy, nonsingular solutions of these stable higher-strength monopoles with eg = 1,(3/2),3. We also give the general stability conditions and the detailed behavior of the interaction potentials between two monopoles which produce the stable higher-strength monopoles

Stable isotopes and biomarkers in microbial ecology

NARCIS (Netherlands)

Boschker, H.T.S.; Middelburg, J.J.

2002-01-01

The use of biomarkers in combination with stable isotope analysis is a new approach in microbial ecology and a number of papers on a variety of subjects have appeared. We will first discuss the techniques for analysing stable isotopes in biomarkers, primarily gas chromatography-combustion-isotope

Stable isotope records for the last 10 000 years from Okshola cave (Fauske, northern Norway and regional comparisons

Directory of Open Access Journals (Sweden)

H. Linge

2009-11-01

Full Text Available The sensitivity of terrestrial environments to past changes in heat transport is expected to be manifested in Holocene climate proxy records on millennial to seasonal timescales. Stalagmite formation in the Okshola cave near Fauske (northern Norway began at about 10.4 ka, soon after the valley was deglaciated. Past monitoring of the cave and surface has revealed stable modern conditions with uniform drip rates, relative humidity and temperature. Stable isotope records from two stalagmites provide time-series spanning from c. 10 380 yr to AD 1997; a banded, multi-coloured stalagmite (Oks82 was formed between 10 380 yr and 5050 yr, whereas a pristine, white stalagmite (FM3 covers the period from ~7500 yr to the present. The stable oxygen isotope (δ¹⁸O_c, stable carbon isotope (δ¹³C_c, and growth rate records are interpreted as showing i a negative correlation between cave/surface temperature and δ¹⁸O_c, ii a positive correlation between wetness and δ¹³C_c, and iii a positive correlation between temperature and growth rate. Following this, the data from Okshola show that the Holocene was characterised by high-variability climate in the early part, low-variability climate in the middle part, and high-variability climate and shifts between two distinct modes in the late part.

A total of nine Scandinavian stalagmite δ¹⁸O_c records of comparable dating precision are now available for parts or most of the Holocene. None of them show a clear Holocene thermal optimum, suggesting that they are influenced by annual mean temperature (cave temperature rather than seasonal temperature. For the last 1000 years, δ¹⁸O_c values display a depletion-enrichment-depletion pattern commonly interpreted as reflecting the conventional view on climate development for the last millennium. Although the δ¹⁸

Malaria infection during pregnancy in area of stable transmission ...

African Journals Online (AJOL)

Malaria infection during pregnancy in area of stable transmission. ... (LBW), a leading cause of neonatal death in areas of stable malaria transmission. ... areas of stable malaria transmission and the effective strategies for prevention and control. Keywords: malaria, pregnancy, semi-immune women, anaemia, low birthweight

Angular Stable Miniplate Fixation of Chronic Unstable Scaphoid Nonunion.

Science.gov (United States)

Schormans, Philip M J; Brink, Peter R G; Poeze, Martijn; Hannemann, Pascal F W

2018-02-01

Background  Around 5 to 15% of all scaphoid fractures result in nonunion. Treatment of long-lasting scaphoid nonunion remains a challenge for the treating surgeon. Healing of scaphoid nonunion is essential for prevention of scaphoid nonunion advanced collapse and the subsequent predictable pattern of radiocarpal osteoarthritis. Purpose  The purpose of this study was to investigate the feasibility of fixation of the scaphoid nonunion with a volar angular stable miniplate and cancellous bone grafting. We hypothesized that this technique could be successful, even in patients with previous surgery for nonunion and in patients with a long duration of nonunion. Patients and Methods  A total of 21 patients enrolled in a single-center prospective cohort study. Healing of nonunion was assessed on multiplanar computed tomography scan of the wrist at a 3-month interval. Functional outcome was assessed by measuring grip strength, range of motion, and by means of the patient-rated wrist and hand evaluation (PRWHE) questionnaire. Results  During follow-up, 19 out of 21 patients (90%) showed radiological healing of the nonunion. The range of motion did not improve significantly. Postoperative PRWHE scores decreased by 34 points. Healing occurred regardless of the length of time of the nonunion (range: 6-183 months) and regardless of previous surgery (38% of patients). Conclusion  Volar angular stable miniplate fixation with autologous cancellous bone grafting is a successful technique for the treatment of chronic unstable scaphoid nonunion, even in patients with long-lasting nonunion and in patients who underwent previous surgery for a scaphoid fracture. Rotational interfragmentary stability might be an important determining factor for the successful treatment of unstable scaphoid nonunion. Level of Evidence  Level IV.

A Stable-Isotope Mass Spectrometry-Based Metabolic Footprinting Approach to Analyze Exudates from Phytoplankton

Directory of Open Access Journals (Sweden)

Mark R. Viant

2013-10-01

Full Text Available Phytoplankton exudates play an important role in pelagic ecology and biogeochemical cycles of elements. Exuded compounds fuel the microbial food web and often encompass bioactive secondary metabolites like sex pheromones, allelochemicals, antibiotics, or feeding attractants that mediate biological interactions. Despite this importance, little is known about the bioactive compounds present in phytoplankton exudates. We report a stable-isotope metabolic footprinting method to characterise exudates from aquatic autotrophs. Exudates from 13C-enriched alga were concentrated by solid phase extraction and analysed by high-resolution Fourier transform ion cyclotron resonance mass spectrometry. We used the harmful algal bloom forming dinoflagellate Alexandrium tamarense to prove the method. An algorithm was developed to automatically pinpoint just those metabolites with highly 13C-enriched isotope signatures, allowing us to discover algal exudates from the complex seawater background. The stable-isotope pattern (SIP of the detected metabolites then allowed for more accurate assignment to an empirical formula, a critical first step in their identification. This automated workflow provides an effective way to explore the chemical nature of the solutes exuded from phytoplankton cells and will facilitate the discovery of novel dissolved bioactive compounds.

Stable water use efficiency under climate change of three sympatric conifer species at the Alpine treeline

Directory of Open Access Journals (Sweden)

Gerhard eWieser

2016-06-01

Full Text Available The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies and Larix decidua trees from 1975-2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ13C and Δ18O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species.

Some implications of changing patterns of mineral consumption

Science.gov (United States)

Menzie, W. David; DeYoung,, John H.; Steblez, Walter G.

2003-01-01

DeYoung and Menzie (1999) examined the relations among population, Gross Domestic Product, and mineral consumption (aluminum, cement, copper, and salt) for Japan, Korea, and the United States between 1965 and 1995. They noted the extremely rapid growth of consumption in Korea between 1975 and 1995. Concomitantly, Korea's population growth rate declined. This paper extends that earlier work by examining patterns of consumption of these same commodities in the twenty most populous countries for the period 1970 through 1995. Developed countries, such as France, Germany, Japan, the United Kingdom, and the United States, show patterns of consumption that are stable (cement, copper, and salt) or grow slowly (aluminum). Some developing countries, including China, Thailand, and Turkey, show more rapid growth of consumption, especially of cement, copper, and aluminum. These changing patterns of mineral consumption in developing countries have important implications -- if they continue, there could be major increases in world mineral consumption and major increases in environmental residuals from mineral production and use. If China reaches the level of consumption of copper of developed countries, world consumption could reach levels more than twice that of 1995 (10.5 million tons).

Stability of nonlinear waves and patterns and related topics

Science.gov (United States)

Ghazaryan, Anna; Lafortune, Stephane; Manukian, Vahagn

2018-04-01

Periodic and localized travelling waves such as wave trains, pulses, fronts and patterns of more complex structure often occur in natural and experimentally built systems. In mathematics, these objects are realized as solutions of nonlinear partial differential equations. The existence, dynamic properties and bifurcations of those solutions are of interest. In particular, their stability is important for applications, as the waves that are observable are usually stable. When the waves are unstable, further investigation is warranted of the way the instability is exhibited, i.e. the nature of the instability, and also coherent structures that appear as a result of an instability of travelling waves. A variety of analytical, numerical and hybrid techniques are used to study travelling waves and their properties. This article is part of the theme issue `Stability of nonlinear waves and patterns and related topics'.

Dynamics and control of twisting bi-stable structures

Science.gov (United States)

Arrieta, Andres F.; van Gemmeren, Valentin; Anderson, Aaron J.; Weaver, Paul M.

2018-02-01

Compliance-based morphing structures have the potential to offer large shape adaptation, high stiffness and low weight, while reducing complexity, friction, and scalability problems of mechanism based systems. A promising class of structure that enables these characteristics are multi-stable structures given their ability to exhibit large deflections and rotations without the expensive need for continuous actuation, with the latter only required intermittently. Furthermore, multi-stable structures exhibit inherently fast response due to the snap-through instability governing changes between stable states, enabling rapid configuration switching between the discrete number of programmed shapes of the structure. In this paper, the design and utilisation of the inherent nonlinear dynamics of bi-stable twisting I-beam structures for actuation with low strain piezoelectric materials is presented. The I-beam structure consists of three compliant components assembled into a monolithic single element, free of moving parts, and showing large deflections between two stable states. Finite element analysis is utilised to uncover the distribution of strain across the width of the flange, guiding the choice of positioning for piezoelectric actuators. In addition, the actuation authority is maximised by calculating the generalised coupling coefficient for different positions of the piezoelectric actuators. The results obtained are employed to tailor and test I-beam designs exhibiting desired large deflection between stable states, while still enabling the activation of snap-through with the low strain piezoelectric actuators. To this end, the dynamic response of the I-beams to piezoelectric excitation is investigated, revealing that resonant excitations are insufficient to dynamically trigger snap-through. A novel bang-bang control strategy, which exploits the nonlinear dynamics of the structure successfully triggers both single and constant snap-through between the stable states

Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

International Nuclear Information System (INIS)

Rastogi, Lori; Kora, Aruna Jyothi; Arunachalam, J.

2012-01-01

A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: ► Method for NaBH 4 reduced and BSA capped gold nanoparticle was standardized. ► Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. ► Nanoparticles are extremely stable towards pH modification and electrolyte addition. ► Antibiotic conjugated nanoparticles exhibited enhanced antibacterial activity

Modelling stable atmospheric boundary layers over snow

NARCIS (Netherlands)

Sterk, H.A.M.

2015-01-01

Thesis entitled:

Modelling Stable Atmospheric Boundary Layers over Snow

H.A.M. Sterk

Wageningen, 29th of April, 2015

Summary

The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs

Moving localized structures and spatial patterns in quadratic media with a saturable absorber

International Nuclear Information System (INIS)

Tlidi, M; Taki, M; Berre, M Le; Reyssayre, E; Tallet, A; Di Menza, L

2004-01-01

For near the first lasing threshold, we give a detailed derivation of a real order parameter equation for the degenerate optical parametric oscillator with a saturable absorber. For this regime, we study analytically the role of the quasi-homogeneous neutral mode in the pattern formation process. We show that this effect stabilized the hexagonal patterns below the lasing threshold. More importantly, we find numerically that when Turing and Hopf bifurcations interact, a stable moving asymmetric localized structure with a constant transverse velocity is generated. The formation of the moving localized structures is analysed for both the propagation and the mean field models. A quantitative confrontation of the two models is discussed

Role of stable isotope analyses in reconstructing past life-histories and the provenancing human skeletal remains: a review

Directory of Open Access Journals (Sweden)

Sehrawat Jagmahender Singh

2017-09-01

Full Text Available This article reviews the present scenario of use of stable isotopes (mainly δ13C, δ15N, δ18O, 87Sr to trace past life behaviours like breast feeding and weaning practices, the geographic origin, migration history, paleodiet and subsistence patterns of past populations from the chemical signatures of isotopes imprinted in human skeletal remains. This approach is based on the state that food-web isotopic signatures are seen in the human bones and teeth and such signatures can change parallely with a variety of biogeochemical processes. By measuring δ13C and δ15N isotopic values of subadult tissues of different ages, the level of breast milk ingestion at particular ages and the components of the complementary foods can be assessed. Strontium and oxygen isotopic analyses have been used for determining the geographic origins and reconstructing the way of life of past populations as these isotopes can map the isotopic outline of the area from where the person acquired water and food during initial lifetime. The isotopic values of strontium and oxygen values are considered specific to geographical areas and serve as reliable chemical signatures of migration history of past human populations (local or non-local to the site. Previous isotopic studies show that the subsistence patterns of the past human populations underwent extensive changes from nomadic to complete agricultural dependence strategies. The carbon and nitrogen isotopic values of local fauna of any archaeological site can be used to elucidate the prominence of freshwater resources in the diet of the past human populations found near the site. More extensive research covering isotopic descriptions of various prehistoric, historic and modern populations is needed to explore the role of stable isotope analysis for provenancing human skeletal remains and assessing human migration patterns/routes, geographic origins, paleodiet and subsistence practices of past populations.

Applications of stable isotope analysis in mammalian ecology.

Science.gov (United States)

Walter, W David; Kurle, Carolyn M; Hopkins, John B

2014-01-01

In this editorial, we provide a brief introduction and summarize the 10 research articles included in this Special Issue on Applications of stable isotope analysis in mammalian ecology. The first three articles report correction and discrimination factors that can be used to more accurately estimate the diets of extinct and extant mammals using stable isotope analysis. The remaining seven applied research articles use stable isotope analysis to address a variety of wildlife conservation and management questions from the oceans to the mountains.

Postural stability in a population of dancers, healthy non-dancers, and vestibular neuritis patients.

Science.gov (United States)

Martin-Sanz, Eduardo; Ortega Crespo, Isabel; Esteban-Sanchez, Jonathan; Sanz, Ricardo

2017-09-01

Several studies have indicated better balance control in dancers than in control participants, but some controversy remains. The aim of our study is to evaluate the postural stability in a cohort of dancers, non-dancers, compensated, and non-compensated unilateral vestibular neuritis (VN). This is a prospective study of control subjects, dancers, and VN patients between June 2009 and December 2015. Dancers from the Dance Conservatory of Madrid and VN patients were referred to our department for analysis. After the clinical history, neuro-otological examination, audiogram, and caloric tests, the diagnosis was done. Results from clinical examination were used for the categorization of compensation situation. A computerized dynamic posturography was performed to every subject. Forty dancers and 38 women formed both 'dancer' and 'normal' cohorts. Forty-two compensated and 39 uncompensated patients formed both 'compensated' and 'uncompensated' cohorts. Dancers had significantly greater antero-posterior (AP) body sway than controls during condition 5 and 6 in the Sensory Organization Test (SOT) (p body sway in every SOT studied condition (p body say in SOT 5 and 6, showed greater values in compensated patients than the control group, the mean analysis did not show any statistical difference between the compensated and dancer groups, in such SOT conditions. Dancers demonstrated greater sways than non-dancers when they relied their postural control on vestibular input alone. Compensated patients had a similar posturographic pattern that the dancers cohort, suggesting a similar shift from visual to somatosensory information.

Clinically stable angina pectoris is not necessarily associated with histologically stable atherosclerotic plaques

NARCIS (Netherlands)

van der Wal, A. C.; Becker, A. E.; Koch, K. T.; Piek, J. J.; Teeling, P.; van der Loos, C. M.; David, G. K.

1996-01-01

OBJECTIVE: To investigate the extent of plaque inflammation in culprit lesions of patients with chronic stable angina. DESIGN: Retrospective study. SETTING: Amsterdam reference centre. SUBJECTS: 89 consecutive patients who underwent directional coronary atherectomy, 58 of whom met the following

Dynamical SUSY breaking in meta-stable vacua

International Nuclear Information System (INIS)

Intriligator, Kenneth; Seiberg, Nathan; Shih, David

2006-01-01

Dynamical supersymmetry breaking in a long-lived meta-stable vacuum is a phenomenologically viable possibility. This relatively unexplored avenue leads to many new models of dynamical supersymmetry breaking. Here, we present a surprisingly simple class of models with meta-stable dynamical supersymmetry breaking: N = 1 supersymmetric QCD, with massive flavors. Though these theories are strongly coupled, we definitively demonstrate the existence of meta-stable vacua by using the free-magnetic dual. Model building challenges, such as large flavor symmetries and the absence of an R-symmetry, are easily accommodated in these theories. Their simplicity also suggests that broken supersymmetry is generic in supersymmetric field theory and in the landscape of string vacua

Impact of mitochondrial Ca2+ cycling on pattern formation and stability.

Science.gov (United States)

Falcke, M; Hudson, J L; Camacho, P; Lechleiter, J D

1999-07-01

Energization of mitochondria significantly alters the pattern of Ca2+ wave activity mediated by activation of the inositol (1,4,5) trisphosphate (IP3) receptor (IP3R) in Xenopus oocytes. The number of pulsatile foci is reduced and spiral Ca2+ waves are no longer observed. Rather, target patterns of Ca2+ release predominate, and when fragmented, fail to form spirals. Ca2+ wave velocity, amplitude, decay time, and periodicity are also increased. We have simulated these experimental findings by supplementing an existing mathematical model with a differential equation for mitochondrial Ca2+ uptake and release. Our calculations show that mitochondrial Ca2+ efflux plays a critical role in pattern formation by prolonging the recovery time of IP3Rs from a refractory state. We also show that under conditions of high energization of mitochondria, the Ca2+ dynamics can become bistable with a second stable stationary state of high resting Ca2+ concentration.

Stable isotope time series and dentin increments elucidate Pleistocene proboscidean paleobiology

Science.gov (United States)

Fisher, Daniel; Rountrey, Adam; Smith, Kathlyn; Fox, David

2010-05-01

Investigations of stable isotope composition of mineralized tissues have added greatly to our knowledge of past climates and dietary behaviors of organisms, even when they are implemented through 'bulk sampling', in which a single assay yields a single, time-averaged value. Likewise, the practice of 'sclerochronology', which documents periodic structural increments comprising a growth record for accretionary tissues, offers insights into rates of growth and age data at a scale of temporal resolution permitted by the nature of structural increments. We combine both of these approaches to analyze dental tissues of late Pleistocene proboscideans. Tusk dentin typically preserves a record of accretionary growth consisting of histologically distinct increments on daily, approximately weekly, and yearly time scales. Working on polished transverse or longitudinal sections, we mill out a succession of temporally controlled dentin samples bounded by clear structural increments with a known position in the sequence of tusk growth. We further subject each sample (or an aliquot thereof) to multiple compositional analyses - most frequently to assess δ18O and δ13C of hydroxyapatite carbonate, and δ13C and δ15N of collagen. This yields, for each animal and each series of years investigated, a set of parallel compositional time series with a temporal resolution of 1-2 months (or finer if we need additional precision). Patterns in variation of thickness of periodic sub-annual increments yield insight into intra-annual and inter-annual variation of tusk growth rate. This is informative even by itself, but it is still more valuable when coupled with compositional time series. Further, the controls on different stable isotope systems are sufficiently different that the data ensemble yields 'much more than the sum of its parts.' By assessing how compositions and growth rates covary, we monitor with greater confidence changes in local climate, diet, behavior, and health status. We

A Comparison between Standard and Functional Clustering Methodologies: Application to Agricultural Fields for Yield Pattern Assessment

Directory of Open Access Journals (Sweden)

Simone Pascucci

2018-04-01

Full Text Available The recognition of spatial patterns within agricultural fields, presenting similar yield potential areas, stable through time, is very important for optimizing agricultural practices. This study proposes the evaluation of different clustering methodologies applied to multispectral satellite time series for retrieving temporally stable (constant patterns in agricultural fields, related to within-field yield spatial distribution. The ability of different clustering procedures for the recognition and mapping of constant patterns in fields of cereal crops was assessed. Crop vigor patterns, considered to be related to soils characteristics, and possibly indicative of yield potential, were derived by applying the different clustering algorithms to time series of Landsat images acquired on 94 agricultural fields near Rome (Italy. Two different approaches were applied and validated using Landsat 7 and 8 archived imagery. The first approach automatically extracts and calculates for each field of interest (FOI the Normalized Difference Vegetation Index (NDVI, then exploits the standard K-means clustering algorithm to derive constant patterns at the field level. The second approach applies novel clustering procedures directly to spectral reflectance time series, in particular: (1 standard K-means; (2 functional K-means; (3 multivariate functional principal components clustering analysis; (4 hierarchical clustering. The different approaches were validated through cluster accuracy estimates on a reference set of FOIs for which yield maps were available for some years. Results show that multivariate functional principal components clustering, with an a priori determination of the optimal number of classes for each FOI, provides a better accuracy than those of standard clustering algorithms. The proposed novel functional clustering methodologies are effective and efficient for constant pattern retrieval and can be used for a sustainable management of

Interactive Stable Ray Tracing

DEFF Research Database (Denmark)

Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig

2017-01-01

Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...

Histomorphological patterns in osseous rests exposed at fire

International Nuclear Information System (INIS)

Medina, C.; Tiesler, V.; Oliva, A.I.; Quintana, P.

2005-01-01

Histomorphology as part of morphological research studies bony structure on the tissue level. Its methods are applied in this investigation to evaluate histomorphological impact patterns in heat-exposed bony material, particularly color changes, fissure patterns, volumetric reduction, and changes in the size of Haversian canals. These variables were evaluated in exposed thin sections of porcine long bones, obtained during two experimental series. The first one was conducted under stable thermal conditions in a furnace by measuring heat impact in stepped time (I to S hours) and temperature intervals (200 to 800 C). During a second experimental phase, bony samples were exposed to direct fire in defined time and heat intervals. The treated specimens were then sectioned and microscopically scrutinized. The results presented here were designed to offer new analytical, measurable standards in the investigation of forms of heat exposition of the human body, applicable in forensics and the study of ancient Maya posthumous body treatments. (Author)

Moving stable solitons in Galileon theory

International Nuclear Information System (INIS)

Masoumi, Ali; Xiao Xiao

2012-01-01

Despite the no-go theorem Endlich et al. (2011) which rules out static stable solitons in Galileon theory, we propose a family of solitons that evade the theorem by traveling at the speed of light. These domain-wall-like solitons are stable under small fluctuations-analysis of perturbation shows neither ghost-like nor tachyon-like instabilities, and perturbative collision of these solitons suggests that they pass through each other asymptotically, which maybe an indication of the integrability of the theory itself.

Patterning nonisometric origami in nematic elastomer sheets

Science.gov (United States)

Plucinsky, Paul; Kowalski, Benjamin A.; White, Timothy J.; Bhattacharya, Kaushik

Nematic elastomers dramatically change their shape in response to diverse stimuli including light and heat. In this paper, we provide a systematic framework for the design of complex three dimensional shapes through the actuation of heterogeneously patterned nematic elastomer sheets. These sheets are composed of \\textit{nonisometric origami} building blocks which, when appropriately linked together, can actuate into a diverse array of three dimensional faceted shapes. We demonstrate both theoretically and experimentally that: 1) the nonisometric origami building blocks actuate in the predicted manner, 2) the integration of multiple building blocks leads to complex multi-stable, yet predictable, shapes, 3) we can bias the actuation experimentally to obtain a desired complex shape amongst the multi-stable shapes. We then show that this experimentally realized functionality enables a rich possible design landscape for actuation using nematic elastomers. We highlight this landscape through theoretical examples, which utilize large arrays of these building blocks to realize a desired three dimensional origami shape. In combination, these results amount to an engineering design principle, which we hope will provide a template for the application of nematic elastomers to emerging technologies.

Gas phase thermal diffusion of stable isotopes

International Nuclear Information System (INIS)

Eck, C.F.

1979-01-01

The separation of stable isotopes at Mound Facility is reviewed from a historical perspective. The historical development of thermal diffusion from a laboratory process to a separation facility that handles all the noble gases is described. In addition, elementary thermal diffusion theory and elementary cascade theory are presented along with a brief review of the uses of stable isotopes

Stable isotope paleoaltimetry and the evolution of landscapes and life

Science.gov (United States)

Mulch, Andreas

2016-01-01

circulation and associated teleconnections in the global climate system that affect δ18O or δD of precipitation; (2) Evaluating on a case-by-case basis if temporal and spatial changes in isotope lapse rates influence interpretations of paleoelevation; (3) Interfacing with phylogenetic techniques to evaluate competing hypotheses with respect to the timing of surface uplift and the diversification of lineages; (4) Characterizing feedbacks between changes in surface elevation and atmospheric circulation as these are likely to be equally important to the diversification of lineages than changes in surface elevation alone. Tackling these challenges will benefit from the accelerating pace of improved data-model comparisons and rapidly evolving geochemical techniques for reconstructing precipitation patterns. Most importantly, stable isotope paleoaltimetry has the potential to develop into a truly interdisciplinary field if innovative tectonic/paleoclimatic and evolutionary biology/phylogenetic approaches are integrated into a common research framework. It therefore, opens new avenues to study the long-term evolution of landscapes and life. article>

Precipitation isotopes link regional climate patterns to water supply in a tropical mountain forest, eastern Puerto Rico

Science.gov (United States)

Scholl, Martha A.; Murphy, Sheila F.

2014-05-01

Like many mountainous areas in the tropics, watersheds in the Luquillo Mountains of eastern Puerto Rico have abundant rainfall and stream discharge and provide much of the water supply for the densely populated metropolitan areas nearby. Projected changes in regional temperature and atmospheric dynamics as a result of global warming suggest that water availability will be affected by changes in rainfall patterns. It is essential to understand the relative importance of different weather systems to water supply to determine how changes in rainfall patterns, interacting with geology and vegetation, will affect the water balance. To help determine the links between climate and water availability, stable isotope signatures of precipitation from different weather systems were established to identify those that are most important in maintaining streamflow and groundwater recharge. Precipitation stable isotope values in the Luquillo Mountains had a large range, from fog/cloud water with δ2H, δ18O values as high as +12 ‰, -0.73 ‰ to tropical storm rain with values as low as -127 ‰, -16.8 ‰. Temporal isotope values exhibit a reverse seasonality from those observed in higher latitude continental watersheds, with higher isotopic values in the winter and lower values in the summer. Despite the higher volume of convective and low-pressure system rainfall, stable isotope analyses indicated that under the current rainfall regime, frequent trade -wind orographic showers contribute much of the groundwater recharge and stream base flow. Analysis of rain events using 20 years of 15 -minute resolution data at a mountain station (643 m) showed an increasing trend in rainfall amount, in agreement with increased precipitable water in the atmosphere, but differing from climate model projections of drying in the region. The mean intensity of rain events also showed an increasing trend. The determination of recharge sources from stable isotope tracers indicates that water supply

Stability properties of nonlinear dynamical systems and evolutionary stable states

Energy Technology Data Exchange (ETDEWEB)

Gleria, Iram, E-mail: iram@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-AL (Brazil); Brenig, Leon [Faculté des Sciences, Université Libre de Bruxelles, 1050 Brussels (Belgium); Rocha Filho, Tarcísio M.; Figueiredo, Annibal [Instituto de Física and International Center for Condensed Matter Physics, Universidade de Brasília, 70919-970 Brasília-DF (Brazil)

2017-03-18

Highlights: • We address the problem of equilibrium stability in a general class of non-linear systems. • We link Evolutionary Stable States (ESS) to stable fixed points of square quasi-polynomial (QP) systems. • We show that an interior ES point may be related to stable interior fixed points of QP systems. - Abstract: In this paper we address the problem of stability in a general class of non-linear systems. We establish a link between the concepts of asymptotic stable interior fixed points of square Quasi-Polynomial systems and evolutionary stable states, a property of some payoff matrices arising from evolutionary games.

Postural stability is compromised by fatiguing overhead work.

Science.gov (United States)

Nussbaum, Maury A

2003-01-01

In a laboratory setting, 16 participants performed a repetitive overhead tapping task for 3 hours or until self-terminated due to substantial shoulder discomfort. Several measures of postural sway and stability were obtained using a force plate, both during quiet standing and during performance of the tapping task. Sway area and peak sway velocity showed consistent increases with time, whereas changes in average velocity and peak whole-body center-of-mass acceleration were either small or nonsignificant. Although relatively insensitive to several task variables, changes in sway areas and peak velocities were substantially larger in trials terminated by the participants. It is argued that fatigue plays a more important role than simple task duration in causing the observed increases in sway, and hence decreases in postural stability. Potential whole-body consequences of localized musculoskeletal stresses appear supported by the results, and implications for safety, risks of falls, and work scheduling are discussed.

24-Hour protein, arginine and citrulline metabolism in fed critically ill children – a stable isotope tracer study

Science.gov (United States)

de Betue, Carlijn T.I.; Garcia Casal, Xiomara C.; van Waardenburg, Dick A.; Schexnayder, Stephen M.; Joosten, Koen F.M.; Deutz, Nicolaas E.P.; Engelen, Marielle P.K.J.

2017-01-01

Background & aims The reference method to study protein and arginine metabolism in critically ill children is measuring plasma amino acid appearances with stable isotopes during a short (4–8h) time period and extrapolate results to 24-hour. However, 24-hour measurements may be variable due to critical illness related factors and a circadian rhythm could be present. Since only short duration stable isotope studies in critically ill children have been conducted before, the aim of this study was to investigate 24-hour appearance of specific amino acids representing protein and arginine metabolism, with stable isotope techniques in continuously fed critically ill children. Methods In eight critically ill children, admitted to the pediatric (n=4) or cardiovascular (n=4) intensive care unit, aged 0–10 years, receiving continuous (par)enteral nutrition with protein intake 1.0–3.7 g/kg/day, a 24-hour stable isotope tracer protocol was carried out. L-[ring-2H5]-phenylalanine, L-[3,3-2H2]-tyrosine, L-[5,5,5-2H3]-leucine, L-[guanido-15N2]-arginine and L-[5-13C-3,3,4,4-2H4]-citrulline were infused intravenously and L-[15N]-phenylalanine and L-[1-13C]leucine enterally. Arterial blood was sampled every hour. Results Coefficients of variation, representing intra-individual variability, of the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline were high, on average 14–19% for intravenous tracers and 23–26% for enteral tracers. No evident circadian rhythm was present. The pattern and overall 24-hour level of whole body protein balance differed per individual. Conclusions In continuously fed stable critically ill children, the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline show high variability. This should be kept in mind when performing stable isotope studies in this population. There was no apparent circadian rhythm. PMID:28089618

Evidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova

Science.gov (United States)

Banerjee, Projjwal; Qian, Yong-Zhong; Heger, Alexander; Haxton, W. C.

2016-11-01

About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of the solar system. A core-collapse supernova, whose shock wave is capable of compressing such a cloud, is an obvious candidate for the initiating event. This hypothesis can be tested because supernovae also produce telltale patterns of short-lived radionuclides, which would be preserved today as isotopic anomalies. Previous studies of the forensic evidence have been inconclusive, finding a pattern of isotopes differing from that produced in conventional supernova models. Here we argue that these difficulties either do not arise or are mitigated if the initiating supernova was a special type, low in mass and explosion energy. Key to our conclusion is the demonstration that short-lived 10Be can be readily synthesized in such supernovae by neutrino interactions, while anomalies in stable isotopes are suppressed.

Axi-symmetric patterns of active polar filaments on spherical and composite surfaces

Science.gov (United States)

Srivastava, Pragya; Rao, Madan

2014-03-01

Experiments performed on Fission Yeast cells of cylindrical and spherical shapes, rod-shaped bacteria and reconstituted cylindrical liposomes suggest the influence of cell geometry on patterning of cortical actin. A theoretical model based on active hydrodynamic description of cortical actin that includes curvature-orientation coupling predicts spontaneous formation of acto-myosin rings, cables and nodes on cylindrical and spherical geometries [P. Srivastava et al, PRL 110, 168104(2013)]. Stability and dynamics of these patterns is also affected by the cellular shape and has been observed in experiments performed on Fission Yeast cells of spherical shape. Motivated by this, we study the stability and dynamics of axi-symmetric patterns of active polar filaments on the surfaces of spherical, saddle shaped and conical geometry and classify the stable steady state patterns on these surfaces. Based on the analysis of the fluorescence images of Myosin-II during ring slippage we propose a simple mechanical model for ring-sliding based on force balance and make quantitative comparison with the experiments performed on Fission Yeast cells. NSF Grant DMR-1004789 and Syracuse Soft Matter Program.

Synthesis of stable ultra-small Cu nanoparticles for direct writing flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Li, Wei [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Chen, Minfang, E-mail: mfchentj@126.com [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2014-01-30

In this study, pure Cu nanoparticles (NPs) have been successfully synthesized and the Cu nano-ink was prepared for direct writing on photo paper using a roller pen. The tri-sodium citrate was used as initial reducing-cum-surfactant agent followed by hydrazine as a second massive reducing agent and cetyltrimethylammonium bromide (CTAB) as extra surfactant agent. From the XRD, TEM, and HR-TEM analyses, the synthesized particles are confirmed to be Cu in spherical shape with sizes range of 2.5 ± 1.0 nm. By analyzing the FT-IR spectroscopy and TGA curves, it was found that the obtained particles capped with tri-sodium citrate and CTAB layers are stable to oxidation up to the temperature 228 °C. The reduced size and enhanced air-stability of the Cu NPs result in an improved particle density upon sintering, which is mainly responsible for the increased conductivity of the Cu patterns. The resistivity of Cu patterns sintered in Ar at 160 °C for 2 h is 7.2 ± 0.6 μΩ cm, which is 4.40 times the bulk Cu resistivity. The drawn Cu lines exhibited excellent integrity and good conductivity, which were experimentally tested. Moreover, a Cu electrode and a sample RFID antenna were successfully made.

Effects of ceftiofur treatment on the susceptibility of commensal porcine E.coli--comparison between treated and untreated animals housed in the same stable.

Science.gov (United States)

Beyer, Anne; Baumann, Sven; Scherz, Gesine; Stahl, Jessica; von Bergen, Martin; Friese, Anika; Roesler, Uwe; Kietzmann, Manfred; Honscha, Walther

2015-10-15

Healthy farm animals have been found to act as a reservoir of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli). Therefore, the objective of the study was to determine the input of antimicrobial active ceftiofur metabolites in the stable via faeces and urine after intramuscular administration of the drug to pigs and the elucidation of the Escherichia coli ESBL resistance pattern of treated and untreated pigs housed in the same barn during therapy. For determination of the minimal inhibitory concentration (MIC) the method of microdilutionaccording to the recommended procedure of the Clinical and Laboratory Standards Institute was used. Inaddition to that, a qualitative determination was performed by agar dilution. Unsusceptible E. coli speciesselected via agar dilution with cefotaxime were confirmed by MALDI-TOF and ESBL encoding genes wereidentified by PCR. The amounts of ceftiofur measured as desfuroylceftiofur (DFC) in the different probes (plasma, urine, faeces and dust) were analysed by UPLC-MS/MS. In a first experiment two groups of pigs (6 animals per group) were housed in the same barn in two separated boxes. One group (group B) were treated with ceftiofur according to the licence (3 mg/kg administered intramuscularly (i.m.) on three consecutive days, day 1-3). During a second treatment period (day 29-31) an increased rate of ESBL resistant E. coli was detectable in these treated pigs and in the air of the stable. Moreover, the second group of animals (group A) formerly untreated but housed for the whole period in the same stable as the treated animals revealed increased resistance rates during their first treatment (day 45-47) with ceftiofur. In order to investigate the environmental input of ceftiofur during therapy and to simulate oral uptake of ceftiofur residues from the air of the stable a second set of experiments were performed. Pigs (6 animals) were treated with an interval of 2 weeks for 3 days with different doses of

On some topological properties of stable measures

DEFF Research Database (Denmark)

Nielsen, Carsten Krabbe

1996-01-01

Summary The paper shows that the set of stable probability measures and the set of Rational Beliefs relative to a given stationary measure are closed in the strong topology, but not closed in the topology of weak convergence. However, subsets of the set of stable probability measures which...... are characterized by uniformity of convergence of the empirical distribution are closed in the topology of weak convergence. It is demonstrated that such subsets exist. In particular, there is an increasing sequence of sets of SIDS measures who's union is the set of all SIDS measures generated by a particular...... system and such that each subset consists of stable measures. The uniformity requirement has a natural interpretation in terms of plausibility of Rational Beliefs...

Electricity deregulation, spot price patterns and demand-side management

International Nuclear Information System (INIS)

Li, Y.; Flynn, P.C.

2006-01-01

This paper examines extensive hourly or half-hourly power price data from 14 deregulated power markets. It analyzes average diurnal patterns, relationship to system load, volatility, and consistency over time. Diurnal patterns indicate the average price spread between off-peak and on-peak and weekend vs. weekday power consumption. Volatility is measured by price velocity: the average normalized hourly change in power price, calculated daily. The calculated price velocity is broken down into an expected component that arises from the diurnal pattern and an unexpected component that arises from unknown factors. The analysis reveals significant differences among markets, suggesting that demand-side management (DSM) of power consumption is far more difficult in some markets than in others. At one extreme, Spain, Britain and Scandinavia show consistent diurnal price patterns, a stable relationship between price and system load, and a low unexplained component of price volatility. A power consumer in these markets could form a reasonable expectation of a reward for DSM of elective power consumption. At the other extreme, two markets in Australia show erratic diurnal price patterns from year to year, low correlation between price and system load, and a high amount of unexpected price velocity. A power consumer in these markets would have far greater difficulty in realizing a benefit from DSM. Markets that experienced one period of very high prices without a clear external cause, such as California and Alberta, appear to have a significant longer-term erosion of public support for deregulation. (author)

Spatial pattern recognition of seismic events in South West Colombia

Science.gov (United States)

Benítez, Hernán D.; Flórez, Juan F.; Duque, Diana P.; Benavides, Alberto; Lucía Baquero, Olga; Quintero, Jiber

2013-09-01

Recognition of seismogenic zones in geographical regions supports seismic hazard studies. This recognition is usually based on visual, qualitative and subjective analysis of data. Spatial pattern recognition provides a well founded means to obtain relevant information from large amounts of data. The purpose of this work is to identify and classify spatial patterns in instrumental data of the South West Colombian seismic database. In this research, clustering tendency analysis validates whether seismic database possesses a clustering structure. A non-supervised fuzzy clustering algorithm creates groups of seismic events. Given the sensitivity of fuzzy clustering algorithms to centroid initial positions, we proposed a methodology to initialize centroids that generates stable partitions with respect to centroid initialization. As a result of this work, a public software tool provides the user with the routines developed for clustering methodology. The analysis of the seismogenic zones obtained reveals meaningful spatial patterns in South-West Colombia. The clustering analysis provides a quantitative location and dispersion of seismogenic zones that facilitates seismological interpretations of seismic activities in South West Colombia.

TOF for heavy stable particle identification

International Nuclear Information System (INIS)

Chang, C.Y.

1983-01-01

Searching for heavy stable particle production in a new energy region of hadron-hadron collisions is of fundamental theoretical interest. Observation of such particles produced in high energy collisions would indicate the existence of stable heavy leptons or any massive hadronic system carrying new quantum numbers. Experimentally, evidence of its production has not been found for PP collisions either at FNAL or at the CERN ISR for √S = 23 and 62 GeV respectively. However, many theories beyond the standard model do predict its existence on a mass scale ranging from 50 to a few hundred GeV. If so, it would make a high luminosity TeV collider an extremely ideal hunting ground for searching the production of such a speculated object. To measure the mass of a heavy stable charged particle, one usually uses its time of flight (TOF) and/or dE/dX information. For heavy neutral particle, one hopes it may decay at some later time after its production. Hence a pair of jets or a jet associated with a high P/sub t/ muon originated from some places other than the interacting point (IP) of the colliding beams may be a good signal. In this note, we examine the feasibility of TOF measurement on a heavy stable particle produced in PP collisions at √S = 1 TeV and a luminosity of 10 33 cm -2 sec -1 with a single arm spectrometer pointing to the IP

Atypical mitochondrial inheritance patterns in eukaryotes.

Science.gov (United States)

Breton, Sophie; Stewart, Donald T

2015-10-01

Mitochondrial DNA (mtDNA) is predominantly maternally inherited in eukaryotes. Diverse molecular mechanisms underlying the phenomenon of strict maternal inheritance (SMI) of mtDNA have been described, but the evolutionary forces responsible for its predominance in eukaryotes remain to be elucidated. Exceptions to SMI have been reported in diverse eukaryotic taxa, leading to the prediction that several distinct molecular mechanisms controlling mtDNA transmission are present among the eukaryotes. We propose that these mechanisms will be better understood by studying the deviations from the predominating pattern of SMI. This minireview summarizes studies on eukaryote species with unusual or rare mitochondrial inheritance patterns, i.e., other than the predominant SMI pattern, such as maternal inheritance of stable heteroplasmy, paternal leakage of mtDNA, biparental and strictly paternal inheritance, and doubly uniparental inheritance of mtDNA. The potential genes and mechanisms involved in controlling mitochondrial inheritance in these organisms are discussed. The linkage between mitochondrial inheritance and sex determination is also discussed, given that the atypical systems of mtDNA inheritance examined in this minireview are frequently found in organisms with uncommon sexual systems such as gynodioecy, monoecy, or andromonoecy. The potential of deviations from SMI for facilitating a better understanding of a number of fundamental questions in biology, such as the evolution of mtDNA inheritance, the coevolution of nuclear and mitochondrial genomes, and, perhaps, the role of mitochondria in sex determination, is considerable.

Stable atomic hydrogen: Polarized atomic beam source

International Nuclear Information System (INIS)

Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

1984-01-01

We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

The Nature of Stable Insomnia Phenotypes

Science.gov (United States)

Pillai, Vivek; Roth, Thomas; Drake, Christopher L.

2015-01-01

Study Objectives: We examined the 1-y stability of four insomnia symptom profiles: sleep onset insomnia; sleep maintenance insomnia; combined onset and maintenance insomnia; and neither criterion (i.e., insomnia cases that do not meet quantitative thresholds for onset or maintenance problems). Insomnia cases that exhibited the same symptom profile over a 1-y period were considered to be phenotypes, and were compared in terms of clinical and demographic characteristics. Design: Longitudinal. Setting: Urban, community-based. Participants: Nine hundred fifty-four adults with Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition based current insomnia (46.6 ± 12.6 y; 69.4% female). Interventions: None. Measurements and results: At baseline, participants were divided into four symptom profile groups based on quantitative criteria. Follow-up assessment 1 y later revealed that approximately 60% of participants retained the same symptom profile, and were hence judged to be phenotypes. Stability varied significantly by phenotype, such that sleep onset insomnia (SOI) was the least stable (42%), whereas combined insomnia (CI) was the most stable (69%). Baseline symptom groups (cross-sectionally defined) differed significantly across various clinical indices, including daytime impairment, depression, and anxiety. Importantly, however, a comparison of stable phenotypes (longitudinally defined) did not reveal any differences in impairment or comorbid psychopathology. Another interesting finding was that whereas all other insomnia phenotypes showed evidence of an elevated wake drive both at night and during the day, the “neither criterion” phenotype did not; this latter phenotype exhibited significantly higher daytime sleepiness despite subthreshold onset and maintenance difficulties. Conclusions: By adopting a stringent, stability-based definition, this study offers timely and important data on the longitudinal trajectory of specific insomnia phenotypes. With

Differences Between Men and Women in Balance and Tremor in Relation to Plantar Fascia Laxity During the Menstrual Cycle.

Science.gov (United States)

Lee, Haneul; Petrofsky, Jerrold

2018-03-01

  Although much attention has been paid to the effect of estrogen on the knee ligaments, little has been done to examine the ligaments in the foot, such as the plantar fascia, and how they may be altered during the menstrual cycle.   To (1) examine sex differences in plantar fascia thickness and laxity and postural sway and (2) identify any menstrual cycle effects on plantar fascia laxity, postural sway, and neuromuscular tremor between menstruation and the ovulation phase.   Case-control study.   Research laboratory.   Fifteen healthy women (age = 25.9 ± 1.8 years) and 15 healthy men (age = 27.3 ± 2.0 years) volunteered to participate in this study.   We asked participants to perform 8 balance tasks on a force platform while we assessed postural sway and tremor.   Plantar fascia length and thickness unloaded and loaded with body weight were measured via ultrasound. Postural sway and tremor were measured using a force platform.   Plantar fascia length and thickness with pressure were greater in ovulating women compared with men ( P women during menstruation and men. Postural sway and tremor were greater at ovulation than during menstruation ( P men had less sway than ovulating women on the 3 most difficult balance tasks ( P women. Postural sway and tremor in men were the same as in women during menstruation. These findings support the need to be aware of the effect of sex hormones on balance to prevent lower extremity injuries during sport activities.

Stable isotope research pool inventory

International Nuclear Information System (INIS)

1986-08-01

This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high-abundance, naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56. All requests for the loan of samples should be submitted with a summary of the purpose of the loan to: Iotope Distribution Office, Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, Tennessee 37831. Requests from non-DOE contractors and from foreign institutions require DOE approval

Long-term stability of tidal and diel-related patterns in mangrove creek fish assemblages in North Brazil

Science.gov (United States)

Castellanos-Galindo, G. A.; Krumme, U.

2014-08-01

Intertidal fish assemblages are thought to respond to tidal and diel rhythms although the assumption that these patterns are stable over long time scales (>1 year) is largely untested. Testing the validity of this assumption is necessary to assess whether short-term temporal patterns, once established, can be extrapolated over time and give a better understanding of the temporal dynamics of fish assemblages in coastal habitats. Here, we compare the fish assemblage structure from two intertidal mangrove creeks in North Brazil (Bragança Peninsula, Caeté estuary) sampled with the same sampling methodology (block nets), effort (two lunar cycles) and design (accounting for the combination of tidal and diel cycle) in the rainy seasons of 1999 and 2012 to evaluate the persistence, stability and recurrence of short-term patterns in the fish community organization. The interaction of tidal and diel cycles (inundations at spring tide-night, spring tide-day, neap tide-night, neap tide-day), found to be stable after 13 years, resulted in recurrent and stable intertidal mangrove fish assemblage compositions. The intertidal mangrove creek fish assemblage consisted of a persistent number of dominant species (seven). However, there were notable changes in fish catch mass, abundance and species dominance between 1999 and 2012. The most severe drought in North Brazil in 30 years, linked to lower precipitation and river runoff in the rainy season of 2012, may have resulted in (1) lower abundance of small juveniles of several dominant species in this assemblage (especially Ariidae - Cathorops agassizii and Sciades herzbergii) and (2) increased dominance of large-sized specimens of the tetraodontid Colomesus psittacus. Our findings highlight: (1) the overriding importance and stability of the interactive pulse of the tidal and diel cycles in determining short-term temporal patterns in intertidal mangrove fish assemblages in neotropical macrotidal estuaries despite the occurrence of

Concentration of stable elements in food products

International Nuclear Information System (INIS)

Montford, M.A.; Shank, K.E.; Hendricks, C.; Oakes, T.W.

1980-01-01

Food samples were taken from commercial markets and analyzed for stable element content. The concentrations of most stable elements (Ag, Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, La, Mg, Mn, Mo, Na, Rb, Sb, Sc, Se, Sr, Ta, Th, Ti, V, Zn, Zr) were determined using multiple-element neutron activation analysis, while the concentrations of other elements (Cd, Hg, Ni, Pb) were determined using atomic absorption. The relevance of the concentrations found are noted in relation to other literature values. An earlier study was extended to include the determination of the concentration of stable elements in home-grown products in the vicinity of the Oak Ridge National Laboratory. Comparisons between the commercial and local food-stuff values are discussed

Evidence for universality and cultural variation of differential emotion response patterning.

Science.gov (United States)

Scherer, K R; Wallbott, H G

1994-02-01

The major controversy concerning psychobiological universality of differential emotion patterning versus cultural relativity of emotional experience is briefly reviewed. Data from a series of cross-cultural questionnaire studies in 37 countries on 5 continents are reported and used to evaluate the respective claims of the proponents in the debate. Results show highly significant main effects and strong effect sizes for the response differences across 7 major emotions (joy, fear, anger, sadness, disgust, shame, and guilt). Profiles of cross-culturally stable differences among the emotions with respect to subjective feeling, physiological symptoms, and expressive behavior are also reported. The empirical evidence is interpreted as supporting theories that postulate both a high degree of universality of differential emotion patterning and important cultural differences in emotion elicitation, regulation, symbolic representation, and social sharing.

Stable isotope views on ecosystem function: challenging or challenged?

Science.gov (United States)

Resco, Víctor; Querejeta, José I; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A; Torres-Cañabate, Patricia; Valladares, Fernando

2010-06-23

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Ubeda, 18-22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes.

Postural adjustments associated with voluntary contraction of leg muscles in standing man.

Science.gov (United States)

Nardone, A; Schieppati, M

1988-01-01

The postural adjustments associated with a voluntary contraction of the postural muscles themselves have been studied in the legs of normal standing men. We focussed on the following questions. Do postural adjustments precede the focal movement as in the case of movements of the upper limb? Which muscle(s) are involved in the task of stabilizing posture? Can the same postural muscle be activated in postural stabilization and in voluntary movement at the same time, in spite of the opposite changes in activity possibly required by these conditions? Six subjects standing on a dynamometric platform were asked to rise onto the tips their toes by contracting their soleus muscles, or to rock on their heels by contracting their tibialis anterior muscles. The tasks were made in a reaction time (RT) situation or in a self-paced mode, standing either freely or holding onto a stable structure. Surface EMGs of leg and thigh muscles, and the foot-floor reaction forces were recorded. The following results were obtained in the RT mode, standing freely. 1. Rising onto toe tips: a striking silent period in soleus preceded its voluntary activation; during this silent period, a tibialis anterior burst could be observed in three subjects; these anticipatory activities induced a forward sway, as monitored by a change in the force exerted along the x axis of the platform. 2. Rocking on heels: an enhancement in tonic EMG of soleus was observed before tibialis anterior voluntary burst, at a mean latency from the go-signal similar to that of the silent period; this anticipatory activity induced a backward body sway. 3. Choice RT conditions showed that the above anticipatory patterns in muscle activity were pre-programmed, specific for the intended tasks, and closely associated with the focal movement. When both tasks were performed in a self-paced mode, all the above EMG and mechanical features were more pronounced and unfolded in time. If the subjects held onto the frame, the early

Equilibrium contact angle or the most-stable contact angle?

Science.gov (United States)

Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

2014-04-01

It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. © 2013 Elsevier B.V. All rights reserved.

Medieval Horse Stable; The Results of Multi Proxy Interdisciplinary Research

Science.gov (United States)

Dejmal, Miroslav; Lisá, Lenka; Fišáková Nývltová, Miriam; Bajer, Aleš; Petr, Libor; Kočár, Petr; Kočárová, Romana; Nejman, Ladislav; Rybníček, Michal; Sůvová, Zdenka; Culp, Randy; Vavrčík, Hanuš

2014-01-01

A multi proxy approach was applied in the reconstruction of the architecture of Medieval horse stable architecture, the maintenance practices associated with that structure as well as horse alimentation at the beginning of 13th century in Central Europe. Finally, an interpretation of the local vegetation structure along Morava River, Czech Republic is presented. The investigated stable experienced two construction phases. The infill was well preserved and its composition reflects maintenance practices. The uppermost part of the infill was composed of fresh stabling, which accumulated within a few months at the end of summer. Horses from different backgrounds were kept in the stable and this is reflected in the results of isotope analyses. Horses were fed meadow grasses as well as woody vegetation, millet, oat, and less commonly hemp, wheat and rye. Three possible explanations of stable usage are suggested. The stable was probably used on a temporary basis for horses of workers employed at the castle, courier horses and horses used in battle. PMID:24670874

Stable isotope labeling strategy based on coding theory

Energy Technology Data Exchange (ETDEWEB)

Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori, E-mail: kigawa@riken.jp [RIKEN Quantitative Biology Center (QBiC), Laboratory for Biomolecular Structure and Dynamics (Japan)

2015-10-15

We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells.

Stable isotope labeling strategy based on coding theory

International Nuclear Information System (INIS)

Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori

2015-01-01

We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells

The use of stable isotopes in medicinal chemistry

International Nuclear Information System (INIS)

Halliday, D.; Thompson, G.N.

1988-01-01

Stable isotopes have been employed increasingly as tracers over the last decade both to provide the clinician with the opportunity to broaden, in a quantitative manner, discrete areas of diagnosis and research, and the clinical chemist with definitive methodology for specific analyte analysis. These non-radioactive 'heavy' isotopes contain one or more extra neutrons in the nucleus compared with their more abundant 'lighter' analogues. Impetus in the application of stable isotopes for in vivo studies has come from an increased awareness of the possible harmful effects in the use of radionuclides, and a realisation of several positive advantages conferred by the use of stable isotopes in their own right - certain elements of clinical importance (especially nitrogen) lack a useable radio-nuclide equivalent; use of a 'cocktail' of stable isotopes permits a range of studies to be performed in the same patient simultaneously and, within specific constraints, serial studies can be performed in the same patients. (author)

Evapotranspiration patterns in complex upland forests reveal contrasting topographic thresholds of non-linearity

Science.gov (United States)

Metzen, D.; Sheridan, G. J.; Benyon, R. G.; Bolstad, P. V.; Nyman, P.; Lane, P. N. J.

2017-12-01

Large areas of forest are often treated as being homogeneous just because they fall in a single climate category. However, we observe strong vegetation patterns in relation to topography in SE Australian forests and thus hypothesise that ET will vary spatially as well. Spatial heterogeneity evolves over different temporal scales in response to climatic forcing with increasing time lag from soil moisture (sub-yearly), to vegetation (10s -100s of years) to soil properties and topography (>100s of years). Most importantly, these processes and time scales are not independent, creating feedbacks that result in "co-evolved stable states" which yield the current spatial terrain, vegetation and ET patterns. We used up-scaled sap flux and understory ET measurements from water-balance plots, as well as LiDAR derived terrain and vegetation information, to infer links between spatio-temporal energy and water fluxes, topography and vegetation patterns at small catchment scale. Topography caused variations in aridity index between polar and equatorial-facing slopes (1.3 vs 1.8), which in turn manifested in significant differences in sapwood area index (6.9 vs 5.8), overstory LAI (3.0 vs 2.3), understory LAI (0.5 vs 0.4), sub-canopy radiation load (4.6 vs 6.8 MJ m-2 d-1), overstory transpiration (501 vs 347 mm a-1) and understory ET (79 vs 155 mm a-1). Large spatial variation in overstory transpiration (195 to 891 mm a-1) was observed over very short distances (100s m); a range representative of diverse forests such as arid open woodlands and wet mountain ash forests. Contrasting, non-linear overstory and understory ET patterns were unveiled between aspects, and topographic thresholds were lower for overstory than understory ET. While ET partitioning remained stable on polar-facing slopes regardless of slope position, overstory contribution gradually decreased with increasing slope inclination on equatorial aspects. Further, we show that ET patterns and controls underlie strong

Axial segregation of granular media rotated in a drum mixer: Pattern evolution

International Nuclear Information System (INIS)

Hill, K.M.; Kakalios, J.; Caprihan, A.

1997-01-01

In the traditional axial segregation effect, a homogeneous mixture of different types of granular material rotated in a drum mixer segregates into surface bands of relatively pure single concentrations along the axis of rotation. This effect primarily has been studied with respect to the initial segregation. However, the initial pattern is not stable, but evolves in time with continued rotation through metastable states of fewer and fewer bands. We describe two experimental studies of this evolution that provide a more complete picture of the dynamics involved in the pattern progression. The use of a charge coupled device camera in conjunction with digital analysis techniques provides a quantitative measure of the state of the surface as a function of time, while magnetic resonance imaging techniques provide a noninvasive method for studying the segregation beneath the surface. These methods indicate that the underlying mechanisms for the pattern evolution may originate in the bulk of the material, beneath the avalanching surface. copyright 1997 The American Physical Society

College students' drinking patterns: trajectories of AUDIT scores during the first four years at university.

Science.gov (United States)

Johnsson, Kent O; Leifman, Anders; Berglund, Mats

2008-01-01

Changes in AUDIT score trajectories were examined in a student population during their first 4 years at a university, including high-risk consumers and a subsample of low-risk consumers. 359 students were selected for the present study, comprising all high-risk consumers (the 27% with highest scores, i.e. 11 for males and 7 for females) and a randomized sample of low-risk consumers (n = 177 and 182, respectively). The Alcohol Use Disorder Identification Test (AUDIT) was used as screening instrument. Trajectory analyses were made using a semiparametric group-based model. In the low-AUDIT group, five distinct trajectories were identified: three stable non-risky consumption groups (83%) and two increasing groups (17%; from non-risky to risky). In the high-AUDIT group, three groups were identified: two stable high groups (58%) and one decreasing group (from risky to non-risky consumption; 41%). In the integrated model, stable risky consumption comprised 16% of the total sample, decreasing consumption 11%, increasing consumption comprised 13% and stable non-risky consumption 60% of the sample. Gender influenced the trajectories. The pattern of changes in risk consumption is similar to that found in corresponding US studies. (c) 2008 S. Karger AG, Basel

Stable structures of Al510–800 clusters and lowest energy sequence of truncated octahedral Al clusters up to 10,000 atoms

International Nuclear Information System (INIS)

Wu, Xia; He, Chengdong

2012-01-01

Highlights: ► The stable structures of Al 510–800 clusters are obtained with the NP-B potential. ► Al 510–800 clusters adopt truncated octahedral (TO) growth pattern based on complete TOs at Al 405 , Al 586 , and Al 711 . ► The lowest energy sequence of complete TOs up to the size 10,000 is proposed. -- Abstract: The stable structures of Al 510–800 clusters are obtained using dynamic lattice searching with constructed cores (DLSc) method by the NP-B potential. According to the structural growth rule, octahedra and truncated octahedra (TO) configurations are adopted as the inner cores in DLSc method. The results show that in the optimized structures two complete TO structures are found at Al 586 and Al 711 . Furthermore, Al 510–800 clusters adopt TO growth pattern on complete TOs at Al 405 , Al 586 , and Al 711 , and the configurations of the surface atoms are investigated. On the other hand, Al clusters with complete TO motifs are studied up to the size 10,000 by the geometrical construction method. The structural characteristics of complete TOs are denoted by the term “family”, and the growth sequence of Al clusters is investigated. The lowest energy sequence of complete TOs is proposed.

Delay-induced cluster patterns in coupled Cayley tree networks

Science.gov (United States)

Singh, A.; Jalan, S.

2013-07-01

We study effects of delay in diffusively coupled logistic maps on the Cayley tree networks. We find that smaller coupling values exhibit sensitiveness to value of delay, and lead to different cluster patterns of self-organized and driven types. Whereas larger coupling strengths exhibit robustness against change in delay values, and lead to stable driven clusters comprising nodes from last generation of the Cayley tree. Furthermore, introduction of delay exhibits suppression as well as enhancement of synchronization depending upon coupling strength values. To the end we discuss the importance of results to understand conflicts and cooperations observed in family business.

How stable 'should' epigenetic modifications be? Insights from adaptive plasticity and bet hedging.

Science.gov (United States)

Herman, Jacob J; Spencer, Hamish G; Donohue, Kathleen; Sultan, Sonia E

2014-03-01

Although there is keen interest in the potential adaptive value of epigenetic variation, it is unclear what conditions favor the stability of these variants either within or across generations. Because epigenetic modifications can be environmentally sensitive, existing theory on adaptive phenotypic plasticity provides relevant insights. Our consideration of this theory suggests that stable maintenance of environmentally induced epigenetic states over an organism's lifetime is most likely to be favored when the organism accurately responds to a single environmental change that subsequently remains constant, or when the environmental change cues an irreversible developmental transition. Stable transmission of adaptive epigenetic states from parents to offspring may be selectively favored when environments vary across generations and the parental environment predicts the offspring environment. The adaptive value of stability beyond a single generation of parent-offspring transmission likely depends on the costs of epigenetic resetting. Epigenetic stability both within and across generations will also depend on the degree and predictability of environmental variation, dispersal patterns, and the (epi)genetic architecture underlying phenotypic responses to environment. We also discuss conditions that favor stability of random epigenetic variants within the context of bet hedging. We conclude by proposing research directions to clarify the adaptive significance of epigenetic stability. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Stable isotopes

International Nuclear Information System (INIS)

Brazier, J.L.; Guinamant, J.L.

1995-01-01