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Sample records for greater postural instability

  1. Cinerama sickness and postural instability.

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    Bos, Jelte E; Ledegang, Wietse D; Lubeck, Astrid J A; Stins, John F

    2013-01-01

    Motion sickness symptoms and increased postural instability induced by motion pictures have been reported in a laboratory, but not in a real cinema. We, therefore, carried out an observational study recording sickness severity and postural instability in 19 subjects before, immediately and 45 min after watching a 1 h 3D aviation documentary in a cinema. Sickness was significantly larger right after the movie than before, and in a lesser extent still so after 45 min. The average standard deviation of the lateral centre of pressure excursions was significantly larger only right afterwards. When low-pass filtered at 0.1 Hz, lateral and for-aft excursions were both significantly larger right after the movie, while for-aft excursions then remained larger even after 45 min. Speculating on previous findings, we predict more sickness and postural instability in 3D than in 2D movies, also suggesting a possible, but yet unknown risk for work-related activities and vehicle operation. Watching motion pictures may be sickening and posturally destabilising, but effects in a cinema are unknown. We, therefore, carried out an observational study showing that sickness then is mainly an issue during the exposure while postural instability is an issue afterwards.

  2. Assessment of postural instability in patients with Parkinson's disease.

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    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.

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

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    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

  4. Postural instability in Charcot-Marie-Tooth 1A disease.

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    Tozza, Stefano; Aceto, Maria Gabriella; Pisciotta, Chiara; Bruzzese, Dario; Iodice, Rosa; Santoro, Lucio; Manganelli, Fiore

    2016-09-01

    The aim of this study was to evaluate the influence of somatosensory impairment, distal muscle weakness and foot deformities on the balance in 21 CMT1A patients using a baropodometric platform. Stabilometric analysis by measuring sway area and velocity of a centre of pressure (CoP) both at open and closed eyes were used to assess postural imbalance. Static analysis, by measuring the load and the plantar surface of forefoot, midfoot and hindfoot was used to define the footprint shape and to assess as a whole foot deformities. Stabilometric and static results were compared with those of a control group. In CMT1A patients, stabilometric findings were correlated with static parameters, Achilles' tendon retraction, distal muscle strength and CMT examination score (CMTES). CMT1A patients compared to controls had lower plantar surface and load on midfoot, and higher load on a forefoot. CMT1A patients had a greater postural instability, since they had a higher CoP velocity, both at open and closed eyes. Moreover, the CoP velocity correlated inversely with the strength of ankle dorsi-flexion muscles and directly with CMTES as whole and with the item "motor symptoms legs". Postural imbalance was not correlated with sensory impairment and foot deformities as expressed by static analysis and Achilles' tendon retraction. In this study we demonstrated an altered balance in CMT1A patients during upright standing. The imbalance in our CMT patients seems to be related to the weakness of ankle dorsi-flexor muscles rather than sensory impairment or foot deformities. These results could be due to a mildly affected CMT1A population, evaluated in an early stage of the disease. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Is Weight-Bearing Asymmetry Associated with Postural Instability after Stroke? A Systematic Review

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    Jip F. Kamphuis

    2013-01-01

    Full Text Available Introduction. Improvement of postural stability is an important goal during poststroke rehabilitation. Since weight-bearing asymmetry (WBA towards the nonparetic leg is common, training of weight-bearing symmetry has been a major focus in post-stroke balance rehabilitation. It is assumed that restoration of a more symmetrical weight distribution is associated with improved postural stability. Objective. To determine to what extent WBA is associated with postural instability in people after stroke. Methods. Electronic databases were searched (Cochrane, MEDLINE, EMBASE, and CINAHL until March 2012. Main Eligibility Criteria. (1 Participants were people after stroke. (2 The association between WBA and postural stability was reported. Quality of reporting was assessed with the STROBE checklist and a related tool for reporting of confounding. Results. Nine observational studies met all criteria. Greater spontaneous WBA was associated with higher center of pressure (COP velocity and with poorer synchronization of COP trajectories between the legs (two and one studies, resp.. Evidence for associations between WBA and performance on clinical balance tests or falls was weak. Conclusion. Greater WBA after stroke was associated with increased postural sway, but the current literature does not provide evidence for a causal relationship. Further studies should investigate whether reducing WBA would improve postural stability.

  6. Can Postural Instability Respond to Galvanic Vestibular Stimulation in Patients with Parkinson’s Disease?

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    Hiroshi Kataoka

    2016-01-01

    Full Text Available Objective Galvanic vestibular stimulation (GVS activates the vestibular afferents, and these changes in vestibular input exert a strong influence on the subject’s posture or standing balance. In patients with Parkinson’s disease (PD, vestibular dysfunction might contribute to postural instability and gait disorders. Methods Current intensity was increased to 0.7 mA, and the current was applied to the patients for 20 minutes. To perform a sham stimulation, the current intensity was increased as described and then decreased to 0 mA over the course of 10 seconds. The patient’s status was recorded continuously for 20 minutes with the patient in the supine position. Results Three out of 5 patients diagnosed with PD with postural instability and/or abnormal axial posture showed a reduction in postural instability after GVS. The score for item 12 of the revised Unified Parkinson’s Disease Rating Scale part 3 was decreased in these patients. Conclusions The mechanism of postural instability is complex and not completely understood. In 2 out of the 5 patients, postural instability was not changed in response to GVS. Nonetheless, the GVS-induced change in postural instability for 3 patients in our study suggests that GVS might be a therapeutic option for postural instability.

  7. Unraveling the mechanisms underlying postural instability in Parkinson's disease using dynamic posturography

    NARCIS (Netherlands)

    Nonnekes, J.H.; Kam, D. de; Geurts, A.C.; Weerdesteijn, V.G.M.; Bloem, B.R.

    2013-01-01

    Postural instability, one of the cardinal symptoms of Parkinson's disease (PD), has devastating consequences for affected patients. Better strategies to prevent falls are needed, but this calls for an improved understanding of the complex mechanisms underlying postural instability. We must also

  8. Spatiotemporal postural control deficits are present in those with chronic ankle instability

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    McKeon Patrick O

    2008-06-01

    Full Text Available Abstract Background Postural control deficits have been purported to be a potential contributing factor in chronic ankle instability (CAI. Summary forceplate measures such as center of pressure velocity and area have not consistently detected postural control deficits associated with CAI. A novel measurement technique derived from the dynamical systems theory of motor control known as Time-to-boundary (TTB has shown promise in detecting deficits in postural control related to chronic ankle instability (CAI. In a previous study, TTB deficits were detected in a sample of females with CAI. The purpose of this study was to examine postural control in sample of males and females with and without CAI using TTB measures. Methods This case-control study was performed in a research laboratory. Thirty-two subjects (18 males, 14 females with self-reported CAI were recruited and matched to healthy controls. All subjects performed three, ten-second trials of single-limb stance on a forceplate with eyes open and eyes closed. Main outcome measures included the TTB absolute minimum (s, mean of TTB minima (s, and standard deviation of TTB minima (s in the anteroposterior and mediolateral directions. A series of group by gender analyses of variance were conducted to evaluate the differences in postural control for all TTB variables separately with eyes open and eyes closed. Results There were no significant group by gender interactions or gender main effects for any of the measures. There, however, significant group main effects for 4 of the 6 measures with eyes closed as the CAI group demonstrated significant deficits in comparison to the control group. There were no significant differences between groups in any of the TTB measures with eyes open. Conclusion TTB deficits were present in the CAI group compared to the control group. These deficits were detected with concurrent removal of visual input. CAI may place significantly greater constraints on the

  9. Modulation of the Fibularis Longus Hoffmann Reflex and Postural Instability Associated With Chronic Ankle Instability

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    Kim, Kyung-Min; Hart, Joseph M.; Saliba, Susan A.; Hertel, Jay

    2016-01-01

    Context: Individuals with chronic ankle instability (CAI) present with decreased modulation of the Hoffmann reflex (H-reflex) from a simple to a more challenging task. The neural alteration is associated with impaired postural control, but the relationship has not been investigated in individuals with CAI. Objective: To determine differences in H-reflex modulation and postural control between individuals with or without CAI and to identify if they are correlated in individuals with CAI. Design: Descriptive laboratory study. Setting: Laboratory. Patients or Other Participants: A total of 15 volunteers with CAI (9 males, 6 females; age = 22.6 ± 5.8 years, height = 174.7 ± 8.1 cm, mass = 74.9 ± 12.8 kg) and 15 healthy sex-matched volunteers serving as controls (9 males, 6 females; age = 23.8 ± 5.8 years, height = 171.9 ± 9.9 cm, mass = 68.9 ± 15.5 kg) participated. Intervention(s): Maximum H-reflex (Hmax) and motor wave (Mmax) from the soleus and fibularis longus were recorded while participants lay prone and then stood in unipedal stance. We assessed postural tasks of unipedal stance with participants' eyes closed for 10 seconds using a forceplate. Main Outcome Measure(s): We normalized Hmax to Mmax to obtain Hmax : Mmax ratios for the 2 positions. For each muscle, H-reflex modulation was quantified using the percentage change scores in Hmax : Mmax ratios calculated from prone position to unipedal stance. Center-of-pressure data were used to compute 4 time-to-boundary variables. Separate independent-samples t tests were performed to determine group differences. Pearson product moment correlation coefficients were calculated between the modulation and balance measures in the CAI group. Results: The CAI group presented less H-reflex modulation in the soleus (t26 = −3.77, P = .001) and fibularis longus (t25 = −2.59, P = .02). The mean of the time-to-boundary minima in the anteroposterior direction was lower in the CAI group (t28 = −2.06, P = .048

  10. Postural instability in Parkinson?s disease ? 120 years after Charcot?s death

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    Hélio Afonso Ghizoni Teive

    2014-08-01

    Full Text Available The authors present the original Charcot’s description of postural instability in Parkinson’s disease as well as the evolution of this sign after 120 years of Charcot’s death.

  11. A weak balance: the contribution of muscle weakness to postural instability and falls.

    NARCIS (Netherlands)

    Horlings, G.C.; Engelen, B.G.M. van; Allum, J.H.J.; Bloem, B.R.

    2008-01-01

    Muscle strength is a potentially important factor contributing to postural control. In this article, we consider the influence of muscle weakness on postural instability and falling. We searched the literature for research evaluating muscle weakness as a risk factor for falls in community-dwelling

  12. Unraveling the mechanisms underlying postural instability in Parkinson's disease using dynamic posturography.

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    Nonnekes, Jorik; de Kam, Digna; Geurts, Alexander C H; Weerdesteyn, Vivian; Bloem, Bastiaan R

    2013-12-01

    Postural instability, one of the cardinal symptoms of Parkinson's disease (PD), has devastating consequences for affected patients. Better strategies to prevent falls are needed, but this calls for an improved understanding of the complex mechanisms underlying postural instability. We must also improve our ability to timely identify patients at risk of falling. Dynamic posturography is a promising avenue to achieve these goals. The latest moveable platforms can deliver 'real-life' balance perturbations, permitting study of everyday fall circumstances. Dynamic posturography studies have shown that PD patients have fundamental problems in scaling their postural responses in accordance with the need of the actual balance task at hand. On-going studies evaluate the predictive ability of impaired posturography performance for daily life falls. We also review recent work aimed at exploring balance correcting steps in PD, and the presumed interaction between startle pathways and postural responses.

  13. Medio-lateral postural instability in subjects with tinnitus

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    Zoi eKapoula

    2011-05-01

    Full Text Available Background: Many patients show modulation of tinnitus by gaze, jaw or neck movements, reflecting abnormal sensorimotor integration and interaction between various inputs. Postural control is based on multi-sensory integration (visual, vestibular, somatosensory, and oculomotor and indeed there is now evidence that posture can also be influenced by sound. Perhaps tinnitus influences posture similarly to external sound. This study examines the quality of postural performance in quiet stance in patients with modulated tinnitus.Methods: Twenty-three patients with highly modulated tinnitus were selected in the ENT service. Twelve reported exclusively or predominately left tinnitus, eight right and three bilateral. Eighteen control subjects were also tested. Subjects were asked to fixate a target at 40cm for 51s; posturography was performed with the platform (Technoconcept, 40Hz for both the eyes open and eyes closed conditions.Results: For both conditions, tinnitus subjects showed abnormally high lateral body sway (SDx. This was corroborated by fast Fourrier Transformation (FFTx and wavelet analysis. For patients with left tinnitus only, medio-lateral sway increased significantly when looking away from the center. Conclusions: Similarly to external sound stimulation, tinnitus could influence lateral sway by activating attention shift, and perhaps vestibular responses. Poor integration of sensorimotor signals is another possibility. Such abnormalities would be accentuated in left tinnitus because of the importance of the right cerebral cortex in processing both auditory-tinnitus and attention.

  14. Postural instability in subjects with Parkinson's disease undergoing different sensory pitfalls

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    Silva, Thaís Cardoso Da; Felippe, Lilian Assunção; Carregaro, Rodrigo Luiz; Christofoletti, Gustavo

    2017-01-01

    Purpose. Previous research has reported postural instability in subjects with Parkinson's disease (PD). However, there are still doubts about the effect of sensory stimuli on one's balance. In this study, we further investigated the stabilometric measures of individuals with PD, analysing the impact

  15. Postural instability in subjects with Parkinson's disease undergoing different sensory pitfalls

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    Silva, Thaís Cardoso Da; Felippe, Lilian Assunção; Carregaro, Rodrigo Luiz; Christofoletti, Gustavo

    2018-01-01

    Purpose. Previous research has reported postural instability in subjects with Parkinson's disease (PD). However, there are still doubts about the effect of sensory stimuli on one's balance. In this study, we further investigated the stabilometric measures of individuals with PD, analysing the impact

  16. Effects of stereotactic neurosurgery on postural instability and gait in Parkinson's disease

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    Bakker, Maaike; Esselink, Rianne A. J.; Munneke, Marten; Limousin-Dowsey, Patricia; Speelman, Hans D.; Bloem, Bastiaan R.

    2004-01-01

    Postural instability and gait disability (PIGD) are disabling signs of Parkinson's disease. Stereotactic surgery aimed at the internal globus pallidus (GPi) or subthalamic nucleus (STN) might improve PIGD, but the precise effects remain unclear. We performed a systematic review of studies that

  17. Individuals with chronic ankle instability exhibit dynamic postural stability deficits and altered unilateral landing biomechanics: A systematic review.

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    Simpson, Jeffrey D; Stewart, Ethan M; Macias, David M; Chander, Harish; Knight, Adam C

    2018-06-13

    To evaluate the literature regarding unilateral landing biomechanics and dynamic postural stability in individuals with and without chronic ankle instability (CAI). Four online databases (PubMed, ScienceDirect, Scopus, and SportDiscus) were searched from the earliest records to 31 January 2018, as well as reference sections of related journal articles, to complete the systematic search. Studies investigating the influence of CAI on unilateral landing biomechanics and dynamic postural stability were systematically reviewed and evaluated. Twenty articles met the criteria and were included in the systematic review. Individuals with CAI were found to have deficits in dynamic postural stability on the affected limb with medium to large effect sizes and altered lower extremity kinematics, most notably in the ankle and knee, with medium to large effect sizes. Additionally, greater loading rates and peak ground reaction forces, in addition to reductions in ankle muscle activity were also found in individuals with CAI during unilateral jump-landing tasks. Individuals with CAI demonstrate dynamic postural stability deficits, lower extremity kinematic alterations, and reduced neuromuscular control during unilateral jump-landings. These are likely factors that contribute recurrent lateral ankle sprain injuries during dynamic activity in individuals with CAI. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Quantitative and clinical description of postural instability in women with breast cancer treated with taxane chemotherapy.

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    Wampler, Meredith A; Topp, Kimberly S; Miaskowski, Christine; Byl, Nancy N; Rugo, Hope S; Hamel, Kate

    2007-08-01

    To describe the postural control of women who received taxane chemotherapy for treatment of breast cancer using quantitative and clinically feasible measures. Prospective descriptive study. University-based comprehensive cancer center. Twenty women who completed taxane treatment for breast cancer and 20 healthy controls participated in this study. Not applicable. Two quantitative measures of postural control were used, Sensory Organization Test (SOT) and center of pressure (COP) velocities. Two clinically feasible measures of postural control were used, the Fullerton Advanced Balance Scale (FABS) and Timed Up & Go (TUG) test. Compared with healthy controls, women with breast cancer had poorer postural control on all of the outcome measures. FABS and TUG scores correlated moderately with SOT and COP scores. After taxane chemotherapy, women with breast cancer show significantly increased postural instability compared with matched controls. Clinically feasible measures of postural control correlated with quantitative tests. These results suggest that these clinical measures may be useful to screen patients to determine who may benefit from rehabilitation.

  19. Primary postural instability: a cause of recurrent sudden falls in the elderly.

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    Djaldetti, R; Lorberboym, M; Melamed, E

    2006-12-01

    Elderly patients with recurrent falls are frequently diagnosed with an extrapyramidal syndrome. This study aims to characterise a distinct group of patients with recurrent falls and postural instability as a hallmark of the clinical examination. The study took place in the Movement Disorders Unit, Rabin Medical Center, Petah Tiqva, Israel among 26 patients with recurrent falls who had no clinical evidence of a neurodegenerative disease. Medical records, neurological examination and brain imaging studies were assessed. Falls in these patients were sudden, unprovoked, with no vertigo or loss of consciousness. All had postural instability with minimal or no abnormality on the neurological examination. Brain imaging showed diffuse ischaemic changes in 65%. [(123)I]-FPCIT SPECT with the dopamine transporter ligand, performed in five patients, was normal in all. Recurrent falls might be caused by a neurological syndrome that primarily affects balance control. The importance of identifying this disorder is its distinction from other parkinsonian syndromes causing falls.

  20. Absence of rotation perception during warm water caloric irrigation in some seniors with postural instability

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    Elodie eChiarovano

    2016-01-01

    Full Text Available Falls in seniors are a major public health problem. Falls lead to fear of falling, reduced mobility and decreased quality of life. Vestibular dysfunction is one of the fall risk factors. The relationship between objective measures of vestibular responses and age has been studied. However, the effects of age on vestibular perception during caloric stimulation have not been studied.Twenty senior subjects were included in the study separated in two groups: 10 seniors reporting postural instability (PI and exhibiting absence of vestibular perception when they tested with caloric stimulation and 10 sex and age-matched seniors with no such problems (controls. We assessed vestibular perception on a binary rating scale during the warm irrigation of the caloric test. The function of the various vestibular receptors was assessed using video-head impulse test (vHIT, caloric tests, and cervical and ocular VEMPs. The Equitest was used to evaluate balance. No horizontal canal dysfunction assessed using both caloric test and vHIT was detected in either group. No significant difference was detected between PI and control groups for the peak SPV of caloric induced ocular nystagmus or for the HVOR gain. All of the controls perceived rotation when the maximal SPV during warm irrigation was equal to or greater than 15°/s. None of the subjects in the PI group perceived rotation even while the peak SPV exceeded 15°/s, providing objective evidence of normal peripheral horizontal canal function. All of the PI group had abnormal Equitest results, particularly in the two last conditions.These investigations show for the first time that vestibular perception can be absent during a caloric test despite normal horizontal canal function. We call this dissociation vestibular neglect. Patients with poor vestibular perception may not be aware of postural perturbations and so will not correct for them. Thus, falls in the elderly may result, amongst other factors, from a

  1. The influence of aging and attentional demands on recovery from postural instability.

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    Stelmach, G E; Zelaznik, H N; Lowe, D

    1990-06-01

    It is well known that the risk of a debilitating injury from a fall is much higher for elderly than for young individuals. In addition, it is well documented that healthy elderly subjects exhibit increased postural sway during normal stance tasks. In the present experiment, we explored the notion that control of minor postural instability in elderly subjects is attention demanding. Postural sway of eight elderly (mean age = 70.0 years) and eight young (mean age = 20.0 years) subjects was measured under two different secondary demands during stable and mildly unstable upright stance. There were two types of work loads. Either a cognitive (math task) or motor (hand-squeeze) task was performed during the second segment of a 50-second standing trial. The effect of these work loads on mean velocity, range, and variability of range of center of foot pressure was measured during the destabilizing activity of arm swinging and subsequent recovery period. Following seven seconds of 1 Hz arm-swinging activity, elderly subjects showed a marked increase in recovery time to normal stance when concurrently performing an arithmetic task. This result suggests that recovery from a posturally destabilizing activity, involving proprioceptive and vestibular information, places increased attentional demands on the postural support system of the elderly.

  2. Postural instability and gait are associated with severity and prognosis of Parkinson disease.

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    van der Heeden, Jorine F; Marinus, Johan; Martinez-Martin, Pablo; Rodriguez-Blazquez, Carmen; Geraedts, Victor J; van Hilten, Jacobus J

    2016-06-14

    Differences in disease progression in Parkinson disease (PD) have variously been attributed to 2 motor subtypes: tremor-dominant (TD) and postural instability and gait difficulty (PIGD)-dominant (PG). We evaluated the role of these phenotypic variants in severity and progression of nondopaminergic manifestations of PD and motor complications. Linear mixed models were applied to data from the Profiling Parkinson's disease (PROPARK) cohort (n = 396) to evaluate the effect of motor subtype on severity and progression of cognitive impairment (Scales for Outcomes in Parkinson's disease [SCOPA]-Cognition [SCOPA-COG]), depression (Hospital Anxiety and Depression Scale [HADS]), autonomic dysfunction (SCOPA-Autonomic [SCOPA-AUT]), excessive daytime sleepiness, psychotic symptoms (SCOPA-Psychiatric Complications [SCOPA-PC]), and motor complications. In first analyses, subtype as determined by the commonly used ratio of tremor over PIGD score was entered as a factor, whereas in second analyses separate tremor and PIGD scores were used. Results were verified in an independent cohort (Estudio Longitudinal de Pacientes con Enfermedad de Parkinson [ELEP]; n = 365). The first analyses showed that PG subtype patients had worse SCOPA-COG, HADS, SCOPA-AUT, SCOPA-PC, and motor complications scores, and exhibited faster progression on the SCOPA-COG. The second analyses showed that only higher PIGD scores were associated with worse scores for these variables; tremor score was not associated with severity or progression of any symptom. Analyses in the independent cohort yielded similar results. In contrast to PIGD, which consistently was associated with greater severity of nondopaminergic symptoms, there was no evidence of a benign effect of tremor. Our findings do not support the use of the TD subtype as a prognostic trait in PD. The results showed that severity of PIGD is a useful indicator of severity and prognosis in PD by itself. © 2016 American Academy of Neurology.

  3. Unipedal postural stability in nonathletes with core instability after intensive abdominal drawing-in maneuver.

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    Lee, Nam G; You, Joshua Sung H; Kim, Tae H; Choi, Bong S

    2015-02-01

    The exact neuromechanical nature and relative contribution of the abdominal drawing-in maneuver (ADIM) to postural instability warrants further investigation in uninjured and injured populations. To determine the effects of the ADIM on static core and unipedal postural stability in nonathletes with core instability. Controlled laboratory study. University research laboratory. A total of 19 nonathletes (4 women: age = 22.3 ± 1.3 years, height = 164.0 ± 1.7 cm, mass = 56.0 ± 4.6 kg; 15 men: age = 24.6 ± 2.8 years, height = 172.6 ± 4.7 cm, mass = 66.8 ± 7.6 kg) with core instability. Participants received ADIM training with visual feedback 20 minutes each day for 7 days each week over a 2-week period. Core instability was determined using a prone formal test and measured by a pressure biofeedback unit. Unipedal postural stability was determined by measuring the center-of-pressure sway and associated changes in the abdominal muscle-thickness ratios. Electromyographic activity was measured concurrently in the external oblique, erector spinae, gluteus medius, vastus medialis oblique, tibialis anterior, and medial gastrocnemius muscles. All participants initially were unable to complete the formal test. However, after the 2-week ADIM training period, all participants were able to reduce the pressure biofeedback unit by a range of 4 to 10 mm Hg from an initial 70 mm Hg and maintain it at 60 to 66 mm Hg with minimal activation of the external oblique (t(18) = 3.691, P = .002) and erector spinae (t(18) = 2.823, P = .01) muscles. Monitoring of the pressure biofeedback unit and other muscle activations confirmed that the correct muscle contraction defining the ADIM was accomplished. This core stabilization was well maintained in the unipedal-stance position, as evidenced by a decrease in the center-of-pressure sway measures (t(18) range, 3.953-5.775, P < .001), an increased muscle-thickness ratio for the transverse abdominis (t(18) = -2.327, P = .03), and a reduction in

  4. Intensive Abdominal Drawing-In Maneuver After Unipedal Postural Stability in Nonathletes With Core Instability

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    Lee, Nam G.; You, Joshua (Sung) H.; Kim, Tae H.; Choi, Bong S.

    2015-01-01

    Context: The exact neuromechanical nature and relative contribution of the abdominal drawing-in maneuver (ADIM) to postural instability warrants further investigation in uninjured and injured populations. Objective: To determine the effects of the ADIM on static core and unipedal postural stability in nonathletes with core instability. Design: Controlled laboratory study. Setting: University research laboratory. Patients or Other Participants: A total of 19 nonathletes (4 women: age = 22.3 ± 1.3 years, height = 164.0 ± 1.7 cm, mass = 56.0 ± 4.6 kg; 15 men: age = 24.6 ± 2.8 years, height = 172.6 ± 4.7 cm, mass = 66.8 ± 7.6 kg) with core instability. Intervention(s): Participants received ADIM training with visual feedback 20 minutes each day for 7 days each week over a 2-week period. Main Outcome Measures(s): Core instability was determined using a prone formal test and measured by a pressure biofeedback unit. Unipedal postural stability was determined by measuring the center-of-pressure sway and associated changes in the abdominal muscle-thickness ratios. Electromyographic activity was measured concurrently in the external oblique, erector spinae, gluteus medius, vastus medialis oblique, tibialis anterior, and medial gastrocnemius muscles. Results: All participants initially were unable to complete the formal test. However, after the 2-week ADIM training period, all participants were able to reduce the pressure biofeedback unit by a range of 4 to 10 mm Hg from an initial 70 mm Hg and maintain it at 60 to 66 mm Hg with minimal activation of the external oblique (t18 = 3.691, P = .002) and erector spinae (t18 = 2.823, P = .01) muscles. Monitoring of the pressure biofeedback unit and other muscle activations confirmed that the correct muscle contraction defining the ADIM was accomplished. This core stabilization was well maintained in the unipedal-stance position, as evidenced by a decrease in the center-of-pressure sway measures (t18 range, 3.953–5.775, P

  5. Postural instability in subjects with parkinson’s disease undergoing different sensory pitfalls

    Directory of Open Access Journals (Sweden)

    Silva Thaís Cardoso Da

    2017-12-01

    Full Text Available Purpose. Previous research has reported postural instability in subjects with Parkinson’s disease (PD. However, there are still doubts about the effect of sensory stimuli on one’s balance. In this study, we further investigated the stabilometric measures of individuals with PD, analysing the impact of different sensory stimuli on the outcomes. Methods. The total of 26 participants (13 with PD and 13 matched control peers were submitted to 8 sensorimotor dynamics differing in relation to support base (30 cm vs. 10 cm, feet in parallel vs. feet in semi-tandem position, contact surface (foam vs. no foam, and visual conditions (eyes open vs. eyes closed. The measures used to assess one’s balance were body position in space, area of support base, and velocity of postural control. The variables involved the anterior-posterior and the mediolateral axes. Participants with PD were evaluated during the off medication state. Mann-Whitney U test and Friedman’s test were applied to carry out inter- and intra-group comparisons. Significance was set at 5%. Results. Cross-sectional analyses illustrated that tasks with sensory pitfalls impacted postural stability to a larger extent in PD subjects. The differences were found in anterior-posterior body position, area of support base, anterior-posterior velocity, and mediolateral velocity. Complementary analyses confirmed considerable instability on balance when support bases were small and visual information was absent (p < 0.05. Conclusions. The current results confirm worse postural stability response in subjects with PD and highlight that the interference of the sensory pitfalls is notable when individuals are off medication.

  6. Comparison of dynamic postural stability scores between athletes with and without chronic ankle instability during lateral jump landing.

    Science.gov (United States)

    Shiravi, Zeinab; Shadmehr, Azadeh; Moghadam, Saeed Talebian; Moghadam, Behrouz Attarbashi

    2017-01-01

    Many ankle injuries occur while participating in sports that require jumping and landing such as basketball, volleyball and soccer. Most recent studies have investigated dynamic postural stability of patients with chronic ankle instability after landing from a forward jump. The present study aimed to investigate the dynamic postural stability of the athletes who suffer from chronic ankle sprain while landing from a lateral jump. Twelve athletes with self-reported unilateral chronic ankle instability (4 females and 8 males) and 12 matched controls (3 females and 9 males) voluntarily participated in the study. Dynamic postural stability index and its directional indices were measured while performing lateral jump landing test. No differences were found between athletes with and without chronic ankle instability during our landing protocol by means of the dynamic postural stability index and its directional indices. Findings showed that in each group, medial/lateral stability index is significantly higher than anterior/posterior and vertical stability indexes. Findings showed that dynamic postural stability was not significantly different between the two groups. Future studies should examine chronic ankle instability patients with more severe disabilities and expose them to more challenging dynamic balance conditions to further explore postural stability. IIIa.

  7. Foam pad of appropriate thickness can improve diagnostic value of foam posturography in detecting postural instability.

    Science.gov (United States)

    Liu, Bo; Leng, Yangming; Zhou, Renhong; Liu, Jingjing; Liu, Dongdong; Liu, Jia; Zhang, Su-Lin; Kong, Wei-Jia

    2018-04-01

    The present study investigated the effect of foam thickness on postural stability in patients with unilateral vestibular hypofunction (UVH) during foam posturography. Static and foam posturography were performed in 33 patients (UVH group) and 30 healthy subjects (control group) with eyes open (EO) and closed (EC) on firm surface and on 1-5 foam pad(s). Sway velocity (SV) of center of pressure, standing time before falling (STBF) and falls reaction were recorded and analyzed. (1) SVs had an increasing tendency in both groups as the foam pads were added under EO and EC conditions. (2) STBFs, only in UVH group with EC, decreased with foam thickness increasing. (3) Significant differences in SV were found between the control and UVH group with EO (except for standing on firm surface, on 1 and 2 foam pad(s)) and with EC (all surface conditions). (4) Receiver operating characteristic curve analysis showed that the SV could better reflect the difference in postural stability between the two groups while standing on the 4 foam pads with EC. Our study showed that diagnostic value of foam posturography in detecting postural instability might be enhanced by using foam pad of right thickness.

  8. Comparison of Postural Stubility and Auditory Short- Term Memory Taks Interference between Patients with Functional Ankle Instability and Healthy Individuals

    Directory of Open Access Journals (Sweden)

    Maryam Hayati

    2010-04-01

    Full Text Available Objective: With increased recognition of the importance of conscious process and cognition activities in the stability and regulation of posture and also in line of probable adaptation in central nervous system in patients with functional ankle instability, this study was aimed to assess interference patterns between short–term memory task and postural stability tasks in functional ankle instability patients in comparison with healthy individuals. Materials & Methods: In this cross–sectional and case–control study, with dual–task paradigm fifteen functional ankle instability patients whom were selected simply and conveniently and fifteen healthy persons whom were matched with patients as control group were assessed and compared. Six steps of tests were performed for every case with two situation of balance Biodex system instability and three situation of auditory short–term memory task. Data were analyzed by repeated measurement ANOVA. Results: Finding showed that there was significant interference between postural task and cognitive task in both groups (P<0.05 , but there was no significant difference between interferences of two groups. Conclusion: Present study, certificated disruption in information processing in a peripheral musculoskeletal injury such as functional ankle instability. Application of training programs in order to facilitate central information processing in balance rehabilitation process of this patients and improved dual–task paradigms with different degrees of cognitive and postural tasks seems to be effective.

  9. Use of Mobile Device Accelerometry to Enhance Evaluation of Postural Instability in Parkinson Disease.

    Science.gov (United States)

    Ozinga, Sarah J; Linder, Susan M; Alberts, Jay L

    2017-04-01

    To determine the accuracy of inertial measurement unit data from a mobile device using the mobile device relative to posturography to quantify postural stability in individuals with Parkinson disease (PD). Criterion standard. Motor control laboratory at a clinic. A sample (N=28) of individuals with mild to moderate PD (n=14) and age-matched community-dwelling individuals without PD (n=14) completed the study. Not applicable. Center of mass (COM) acceleration measures were compared between the mobile device and the NeuroCom force platform to determine the accuracy of mobile device measurements during performance of the Sensory Organization Test (SOT). Analyses examined test-retest reliability of both systems and sensitivity of (1) the equilibrium score from the SOT and (2) COM acceleration measures from the force platform and mobile device to quantify postural stability across populations. Metrics of COM acceleration from inertial measurement unit data and the NeuroCom force platform were significantly correlated across balance conditions and groups (Pearson r range, .35 to .97). The SOT equilibrium scores failed to discriminate individuals with and without PD. However, the multiplanar measures of COM acceleration from the mobile device exhibited good to excellent reliability across SOT conditions and were able to discriminate individuals with and without PD in conditions with the greatest balance demands. Metrics employing medial-lateral movement produce a more sensitive outcome than the equilibrium score in identifying postural instability associated with PD. Overall, the output from the mobile device provides an accurate and reliable method of rapidly quantifying balance in individuals with PD. The portable and affordable nature of a mobile device with the application makes it ideally suited to use biomechanical data to aid in clinical decision making. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  10. The Effect of Fatigue and Instability on Postural Control Parameters in Standing Posture in Healthy Adults and Patients with Chronic Low Back Pain

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    Amir Hosein Kahlaee

    2012-06-01

    Full Text Available Background: This study aims at analyzing the effect of fatigue and instability on postural control parameters in both healthy people and patients with the chronic nonspecific low-back pain.Materials and Methods: In this non-experimental case-control study, oscillations of center of pressure were statistically analyzed in 16 healthy people and 15 patients with the chronic nonspecific low back pain. The analysis was conducted through two stages: before and after fatigue and under both stable and unstable surfaces. Results: Under the pre-fatigue, stable condition, there was not any difference between the two groups. Both fatigue and unstable surface changed our variables (sway area, range, velocity, frequency and total power of the signal. All the changes in variables were significant in the low-back pain group; while changes in the healthy group only covered the time-domain variables. The effect of instability was higher than that of fatigue. Conclusion: The postural control system for patients with low-back pain before fatigue and under stable condition, revealed sufficient competence to provide postural stability and its function cannot be differentiated from that in healthy people. Meanwhile, different mechanisms were used by these patients to confront stability challenging factors and further neural activity was required to counteract such factors.

  11. The effectiveness of foot orthotics in improving postural control in individuals with chronic ankle instability: a critically appraised topic.

    Science.gov (United States)

    Gabriner, Michael L; Braun, Brittany A; Houston, Megan N; Hoch, Matthew C

    2015-02-01

    Chronic ankle instability (CAI) is a condition commonly experienced by physically active individuals. It has been suggested that foot orthotics may increase a CAI patient's postural control. For patients with CAI, is there evidence to suggest that an orthotic intervention will help improve postural control? The literature was searched for studies of level 2 evidence or higher that investigated the effects of foot orthotics on postural control in patients with CAI. The search of the literature produced 5 possible studies for inclusion; 2 studies met the inclusion criteria and were included. One randomized controlled trial and 1 outcomes study were included. Foot orthotics appear to be effective at improving postural control in patients with CAI. There is moderate evidence to support the use of foot orthotics in the treatment of CAI to help improve postural control. There is grade B evidence that foot orthotics help improve postural control in people with CAI. The Centre of Evidence Based Medicine recommends a grade of B for level 2 evidence with consistent findings.

  12. Postural instability detection: aging and the complexity of spatial-temporal distributional patterns for virtually contacting the stability boundary in human stance.

    Directory of Open Access Journals (Sweden)

    Melissa C Kilby

    Full Text Available Falls among the older population can severely restrict their functional mobility and even cause death. Therefore, it is crucial to understand the mechanisms and conditions that cause falls, for which it is important to develop a predictive model of falls. One critical quantity for postural instability detection and prediction is the instantaneous stability of quiet upright stance based on motion data. However, well-established measures in the field of motor control that quantify overall postural stability using center-of-pressure (COP or center-of-mass (COM fluctuations are inadequate predictors of instantaneous stability. For this reason, 2D COP/COM virtual-time-to-contact (VTC is investigated to detect the postural stability deficits of healthy older people compared to young adults. VTC predicts the temporal safety margin to the functional stability boundary ( =  limits of the region of feasible COP or COM displacement and, therefore, provides an index of the risk of losing postural stability. The spatial directions with increased instability were also determined using quantities of VTC that have not previously been considered. Further, Lempel-Ziv-Complexity (LZC, a measure suitable for on-line monitoring of stability/instability, was applied to explore the temporal structure or complexity of VTC and the predictability of future postural instability based on previous behavior. These features were examined as a function of age, vision and different load weighting on the legs. The primary findings showed that for old adults the stability boundary was contracted and VTC reduced. Furthermore, the complexity decreased with aging and the direction with highest postural instability also changed in aging compared to the young adults. The findings reveal the sensitivity of the time dependent properties of 2D VTC to the detection of postural instability in aging, availability of visual information and postural stance and potential applicability as a

  13. Virtual Reality Telerehabilitation for Postural Instability in Parkinson’s Disease: A Multicenter, Single-Blind, Randomized, Controlled Trial

    Directory of Open Access Journals (Sweden)

    Marialuisa Gandolfi

    2017-01-01

    Full Text Available Introduction. Telerehabilitation enables patients to access remote rehabilitation services for patient-physiotherapist videoconferencing in their own homes. Home-based virtual reality (VR balance training has been shown to reduce postural instability in patients with Parkinson’s disease (PD. The primary aim was to compare improvements in postural stability after remotely supervised in-home VR balance training and in-clinic sensory integration balance training (SIBT. Methods. In this multicenter study, 76 PD patients (modified Hoehn and Yahr stages 2.5–3 were randomly assigned to receive either in-home VR telerehabilitation (n=38 or in-clinic SIBT (n=38 in 21 sessions of 50 minutes each, 3 days/week for 7 consecutive weeks. VR telerehabilitation consisted of graded exergames using the Nintendo Wii Fit system; SIBT included exercises to improve postural stability. Patients were evaluated before treatment, after treatment, and at 1-month follow-up. Results. Analysis revealed significant between-group differences in improvement on the Berg Balance Scale for the VR telerehabilitation group (p=0.04 and significant Time × Group interactions in the Dynamic Gait Index (p=0.04 for the in-clinic group. Both groups showed differences in all outcome measures over time, except for fall frequency. Cost comparison yielded between-group differences in treatment and equipment costs. Conclusions. VR is a feasible alternative to in-clinic SIBT for reducing postural instability in PD patients having a caregiver.

  14. Association of postural instability with asymptomatic cerebrovascular damage and cognitive decline: the Japan Shimanami health promoting program study.

    Science.gov (United States)

    Tabara, Yasuharu; Okada, Yoko; Ohara, Maya; Uetani, Eri; Kido, Tomoko; Ochi, Namiko; Nagai, Tokihisa; Igase, Michiya; Miki, Tetsuro; Matsuda, Fumihiko; Kohara, Katsuhiko

    2015-01-01

    Asymptomatic cerebral small-vessel disease (cSVD) in elderly individuals are potent risk factors for stroke. In addition to common clinical risk factors, postural instability has been postulated to be associated with cSVD in older frail patients. Here, we conducted a cross-sectional study to understand the possible link between postural instability and asymptomatic cSVD further, namely periventricular hyperintensity, lacunar infarction, and microbleeds, as well as cognitive function, in a middle-aged to elderly general population (n=1387). Postural instability was assessed based on one-leg standing time (OLST) and posturography findings. cSVD was evaluated by brain MRI. Mild cognitive impairment was assessed using a computer-based questionnaire, and carotid intima-media thickness as an index of atherosclerosis was measured via ultrasonography. Frequency of short OLST, in particular 2, 34.5%; microbleeds lesion: none, 10.1%; 1, 15.3%; >2, 30.0%; periventricular hyperintensity grade: 0, 5.7%; 1, 11.5%; >2, 23.7%). The association of short OLST with lacunar infarction and microbleeds but not periventricular hyperintensity remained significant even after adjustment for possible covariates (lacunar infarction, P=0.009; microbleeds, P=0.003; periventricular hyperintensity, P=0.601). In contrast, no significant association was found between posturographic parameters and cSVD, whereas these parameters were linearly associated with OLST. Short OLST was also significantly associated with reduced cognitive function independent of covariates, including cSVD (P=0.002). Postural instability was found to be associated with early pathological changes in the brain and functional decline, even in apparently healthy subjects. © 2014 American Heart Association, Inc.

  15. The effect of medication and the role of postural instability in different components of freezing of gait (FOG).

    Science.gov (United States)

    Nantel, Julie; Bronte-Stewart, Helen

    2014-04-01

    Freezing of gait (FOG) is associated with gait asymmetry and arrhythmicity, cognitive impairment in Parkinson's disease (PD). However, the role of postural instability (PI) in and the effect of dopaminergic medication (meds) on FOG are unclear. We investigated the effect of meds on FOG using a validated metric, Stepping in Place (SIP) and the relationship between PI and FOG. We assessed static posturography (off meds), SIP, UPDRS-III (off/on meds) and the FOG-questionnaire (FOG-Q) in 15 freezers/15 non-freezers and 14 healthy controls. UPDRS-III, rigidity, tremor (P FOG-Q was correlated with CoP anteroposterior displacement and mediolateral VCoP (R = 0.42; R = 0.40, P FOG frequency and duration but not of gait asymmetry and arrhythmicity on meds suggests that both dopaminergic and non-dopaminergic networks contribute to FOG. The correlations between postural instability and FOG severity and SIP asymmetry on meds, suggest that as the disease progresses, postural instability interferes with gait symmetry and lead to on meds FOG and falls. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Longer reaction time of the fibularis longus muscle and reduced postural control in basketball players with functional ankle instability: A pilot study.

    Science.gov (United States)

    Méndez-Rebolledo, Guillermo; Guzmán-Muñoz, Eduardo; Gatica-Rojas, Valeska; Zbinden-Foncea, Hermann

    2015-08-01

    Motor control evaluation in subjects with functional ankle instability is questionable when both ankles of the same subject are compared (affected vs non-affected). To compare the postural control and reaction time of ankle muscles among: basketball players with FAI (instability group), basketball players without FAI (non-instability group) and healthy non-basketball-playing participants (control group). Case-control study. Laboratory. Instability (n = 10), non-instability (n = 10), and control groups (n = 11). Centre of pressure variables (area, velocity and sway) were measured with a force platform. Reaction time of ankle muscles was measured via electromyography. A one-way ANOVA demonstrated that there were significant differences between the instability and non-instability groups in the fibularis longus (p postural control and longer reaction time of the fibularis and tibialis anterior muscles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Absence of Rotation Perception during Warm Water Caloric Irrigation in Some Seniors with Postural Instability.

    Science.gov (United States)

    Chiarovano, Elodie; Vidal, Pierre-Paul; Magnani, Christophe; Lamas, Georges; Curthoys, Ian S; de Waele, Catherine

    2016-01-01

    Falls in seniors are a major public health problem. Falls lead to fear of falling, reduced mobility, and decreased quality of life. Vestibular dysfunction is one of the fall risk factors. The relationship between objective measures of vestibular responses and age has been studied. However, the effects of age on vestibular perception during caloric stimulation have not been studied. Twenty senior subjects were included in the study, and separated in two groups: 10 seniors reporting postural instability (PI) and exhibiting absence of vestibular perception when they tested with caloric stimulation and 10 sex- and age-matched seniors with no such problems (controls). We assessed vestibular perception on a binary rating scale during the warm irrigation of the caloric test. The function of the various vestibular receptors was assessed using video head impulse test (vHIT), caloric tests, and cervical and ocular vestibular-evoked myogenic potentials. The Equitest was used to evaluate balance. No horizontal canal dysfunction assessed using both caloric test and vHIT was detected in either group. No significant difference was detected between PI and control groups for the peak SPV of caloric-induced ocular nystagmus or for the HVOR gain. All the controls perceived rotation when the maximal SPV during warm irrigation was equal to or ≥15°/s. None of the subjects in the PI group perceived rotation even while the peak SPV exceeded 15°/s, providing objective evidence of normal peripheral horizontal canal function. All the PI group had abnormal Equitest results, particularly in the two last conditions. These investigations show for the first time that vestibular perception can be absent during a caloric test despite normal horizontal canal function. We call this as dissociation vestibular neglect. Patients with poor vestibular perception may not be aware of postural perturbations and so will not correct for them. Thus, falls in the elderly may result, among other factors, from

  18. Differential effect of environmental risk factors on postural instability gait difficulties and tremor dominant Parkinson's disease.

    Science.gov (United States)

    Skeie, G O; Muller, B; Haugarvoll, K; Larsen, J P; Tysnes, O B

    2010-09-15

    Both environmental and genetic factors contribute to the development of Parkinson's disease (PD). We have examined environmental risk factors in a Norwegian population of incident PD patients and controls, the Norwegian ParkWest study. All five neurological wards in the study area of Western Norway participated in the study. A 4-step diagnostic procedure was used to establish a representative cohort of patients with incident PD at a high level of diagnostic accuracy. 212 incident PD patients and 175 age- and gender-matched controls were included. PD patients and controls were asked for information on occupation, education, exposure to pesticides, tobacco, alcohol, and caffeine. Agricultural work was associated with a higher risk of PD (OR 1.75 (1.03-3.0) P = 0.009). There were no differences as to other occupations. Smoking (OR 0.63 (0.42-0.95) P = 0.016) and alcohol use (OR 0.55 P = 0.008) were associated with a lower risk for PD. Interestingly, this inverse association was only seen in postural instability gait difficulties (PIGD) PD (P = 0.046 for smoking, P = 0.07 for alcohol consumption), and not in tremor dominant (TD) PD which was similar to controls. Consumption of coffee was lower in PD patients (3.3 ± 1.8 cups per day vs. 3.8 ± 2.0 in controls P = 0.02). In the regression model including intake of alcohol, coffee, and smoke, only coffee (P = 0.007) and alcohol intake (P = 0.021) remained significant whereas smoking was no longer significant. Thus, it seems as though only coffee intake reduces the risk of PD in general while associations to alcohol and smoking differ between PIGD and TD-PD patients. © 2010 Movement Disorder Society.

  19. Changes in Postural Control After a Ball-Kicking Balance Exercise in Individuals With Chronic Ankle Instability

    Science.gov (United States)

    Conceição, Josilene Souza; Schaefer de Araújo, Felipe Gustavo; Santos, Gilmar Moraes; Keighley, John

    2016-01-01

    Context:  Rehabilitation programs for patients with chronic ankle instability (CAI) generally involve balance-perturbation training (BPT). Anticipatory postural adjustments (APAs) and compensatory postural adjustments (CPAs) are the primary strategies used to maintain equilibrium during body perturbations. Little is known, however, about how APAs and CPAs are modified to promote better postural control for individuals with CAI after BPT. Objective:  To investigate the effect of BPT that involves kicking a ball on postural-control strategies in individuals with CAI. Design:  Randomized controlled clinical trial. Setting:  Laboratory. Patients or Other Participants:  We randomly assigned 44 volunteers with CAI to either a training group (TG; 11 women, 11 men; age = 24 ± 4 years, height = 173.0 ± 9.8 cm, mass = 72.64 ± 11.98 kg) or control group (CG; 11 women, 11 men; age = 22 ± 3 years, height = 171.0 ± 9.7 cm, mass = 70.00 ± 11.03 kg). Intervention(s):  The TG performed a single 30-minute training session that involved kicking a ball while standing on 1 foot. The CG received no intervention. Main Outcome Measure(s):  The primary outcome was the sum of the integrated electromyographic activity (∑∫EMG) of the lower extremity muscles in the supporting limb that were calculated during typical intervals for APAs and CPAs. A secondary outcome was center-of-pressure displacement during similar intervals. Results:  In the TG after training, the ∑∫EMG decreased in both dorsal and ventral muscles during compensatory adjustment (ie, the time interval that followed lower limb movement). During this interval, muscle activity (∑∫EMG) was less in the TG than in the CG. Consequently, center-of-pressure displacement increased during the task after training. Conclusions:  A single session of ball-kicking BPT promoted changes in postural-control strategies in individuals with CAI. These results should stimulate new and more comprehensive studies to

  20. Spherical Lenses and Prisms Lead to Postural Instability in Both Dyslexic and Non Dyslexic Adolescents

    Science.gov (United States)

    Kapoula, Zoi; Gaertner, Chrystal; Matheron, Eric

    2012-01-01

    There is controversy as to whether dyslexic children present systematic postural deficiency. Clinicians use a combination of ophthalmic prisms and proprioceptive soles to improve postural performances. This study examines the effects of convergent prisms and spherical lenses on posture. Fourteen dyslexics (13–17 years-old) and 11 non dyslexics (13–16 years-old) participated in the study. Quiet stance posturography was performed with the TechnoConcept device while subjects fixated a target at eye-level from a distance of 1_m. Four conditions were run: normal viewing; viewing the target with spherical lenses of −1 diopter (ACCOM1) over each eye; viewing with −3 diopters over each eye (ACCOM3); viewing with a convergent prism of 8 diopters per eye. Relative to normal viewing, the −1 lenses increased the surface of body sway significantly whereas the −3 diopter lenses only resulted in a significant increase of antero-posterior body sway. Thus, adolescents would appear to cope more effectively with stronger conflicts rather than subtle ones. The prism condition resulted in a significant increase in both the surface and the antero-posterior body sway. Importantly, all of these effects were similar for the two groups. Wavelet analysis (time frequency domain) revealed high spectral power of antero-posterior sway for the prism condition in both groups. In the ACCOM3 condition, the spectral power of antero-posterior sway decreased for non dyslexics but increased for dyslexics suggesting that dyslexics encounter more difficulty with accommodation. The cancelling time for medium range frequency (believed to be controlled by the cerebellum), was shorter in dyslexics, suggesting fewer instances of optimal control. We conclude that dyslexics achieve similar postural performances albeit less efficiently. Prisms and lenses destabilize posture for all teenagers. Thus, contrary to adults, adolescents do not seem to use efferent, proprioceptive ocular motor signals to

  1. Spherical lenses and prisms lead to postural instability in both dyslexic and non dyslexic adolescents.

    Directory of Open Access Journals (Sweden)

    Zoi Kapoula

    Full Text Available There is controversy as to whether dyslexic children present systematic postural deficiency. Clinicians use a combination of ophthalmic prisms and proprioceptive soles to improve postural performances. This study examines the effects of convergent prisms and spherical lenses on posture. Fourteen dyslexics (13-17 years-old and 11 non dyslexics (13-16 years-old participated in the study. Quiet stance posturography was performed with the TechnoConcept device while subjects fixated a target at eye-level from a distance of 1_m. Four conditions were run: normal viewing; viewing the target with spherical lenses of -1 diopter (ACCOM1 over each eye; viewing with -3 diopters over each eye (ACCOM3; viewing with a convergent prism of 8 diopters per eye. Relative to normal viewing, the -1 lenses increased the surface of body sway significantly whereas the -3 diopter lenses only resulted in a significant increase of antero-posterior body sway. Thus, adolescents would appear to cope more effectively with stronger conflicts rather than subtle ones. The prism condition resulted in a significant increase in both the surface and the antero-posterior body sway. Importantly, all of these effects were similar for the two groups. Wavelet analysis (time frequency domain revealed high spectral power of antero-posterior sway for the prism condition in both groups. In the ACCOM3 condition, the spectral power of antero-posterior sway decreased for non dyslexics but increased for dyslexics suggesting that dyslexics encounter more difficulty with accommodation. The cancelling time for medium range frequency (believed to be controlled by the cerebellum, was shorter in dyslexics, suggesting fewer instances of optimal control. We conclude that dyslexics achieve similar postural performances albeit less efficiently. Prisms and lenses destabilize posture for all teenagers. Thus, contrary to adults, adolescents do not seem to use efferent, proprioceptive ocular motor signals to

  2. Face piercing (body art: choosing pleasure vs. possible pain and posture instability

    Directory of Open Access Journals (Sweden)

    Eric eMatheron

    2011-09-01

    Full Text Available Piercings (body art, i.e. with jewelry are more and more widespread. They can induce various complications such as infections, allergies, headaches, and various skin, cartilage, or dental problems which will lead to economic effects on health-care systems. We draw attention to other possible side effects resulting from face piercing complications such as eye misalignment, decreased postural control efficiency, and nonspecific chronic back pain. We found that the origin was pierced jewelry on the face. Removing the jewelry restored eye alignment, improved postural control, and alleviated back pain in a lasting way. This observation is important for health; further investigations would be of interest.

  3. Light touch contact improves pain-evoked postural instability during quiet standing

    DEFF Research Database (Denmark)

    Hirata, Rogerio P.; Christensen, Steffan W.; Agger, Simone

    2018-01-01

    for 40 seconds with their eyes closed. Their postural stability was quantified by the area and velocity of center of pressure (CoP) displacement. The CoP was recorded with and without pain during two different conditions: 1) no touch and 2) the subjects were asked to lightly touch a curtain...

  4. Is weight-bearing asymmetry associated with postural instability after stroke? A systematic review.

    NARCIS (Netherlands)

    Kamphuis, J.F.; Kam, D.C.J. de; Geurts, A.C.H.; Weerdesteijn, V.G.M.

    2013-01-01

    Introduction. Improvement of postural stability is an important goal during poststroke rehabilitation. Since weight-bearing asymmetry (WBA) towards the nonparetic leg is common, training of weight-bearing symmetry has been a major focus in post-stroke balance rehabilitation. It is assumed that

  5. Subthalamic nucleus stimulation and levodopa-resistant postural instability in Parkinson's disease.

    NARCIS (Netherlands)

    Visser, J.E.; Allum, J.H.J.; Carpenter, M.G.; Esselink, R.A.J.; Speelman, J.D.; Borm, G.F.; Bloem, B.R.

    2008-01-01

    We examined the effect of bilateral subthalamic nucleus stimulation on levodopa-resistant balance impairment in 14 patients with Parkinson's disease and 18 matched controls. Instability was quantitatively assessed using standardized multidirectional dynamic posturography. Patients were tested after

  6. Subthalamic nucleus stimulation and levodopa-resistant postural instability in Parkinson's disease

    NARCIS (Netherlands)

    Visser, Jasper E.; Allum, John H. J.; Carpenter, Mark G.; Esselink, Rianne A.; Speelman, Johannes D.; Borm, George F.; Bloem, Bastiaan R.

    2008-01-01

    We examined the effect of bilateral subthalamic nucleus stimulation on levodopa-resistant balance impairment in 14 patients with Parkinson's disease and 18 matched controls. Instability was quantitatively assessed using standardized multidirectional dynamic posturography. Patients were tested after

  7. Assessment of Relationships Between Joint Motion Quality and Postural Control in Patients With Chronic Ankle Joint Instability.

    Science.gov (United States)

    Bączkowicz, Dawid; Falkowski, Krzysztof; Majorczyk, Edyta

    2017-08-01

    Study Design Controlled laboratory study, cross-sectional. Background Lateral ankle sprains are among the most common injuries encountered during athletic participation. Following the initial injury, there is an alarmingly high risk of reinjury and development of chronic ankle instability (CAI), which is dependent on a combination of factors, including sensorimotor deficits and changes in the biomechanical environment of the ankle joint. Objective To evaluate CAI-related disturbances in arthrokinematic motion quality and postural control and the relationships between them. Methods Sixty-three male subjects (31 with CAI and 32 healthy controls) were enrolled in the study. For arthrokinematic motion quality analysis, the vibroarthrographic signals were collected during ankle flexion/extension motion using an acceleration sensor and described by variability (variance of mean squares [VMS]), amplitude (mean of 4 maximal and 4 minimal values [R4]), and frequency (vibroarthrographic signal bands of 50 to 250 Hz [P1] and 250 to 450 Hz [P2]) parameters. Using the Biodex Balance System, single-leg dynamic balance was measured by overall, anteroposterior, and mediolateral stability indices. Results Values of vibroarthrographic parameters (VMS, R4, P1 and P2) were significantly higher in the CAI group than those in the control group (Pankle arthrokinematic motion and postural control were present. Therefore, physical therapy interventions focused on improving ankle neuromuscular control and arthrokinematic function are necessary in CAI patient care. J Orthop Sports Phys Ther 2017;47(8):570-577. Epub 4 Nov 2016. doi:10.2519/jospt.2017.6836.

  8. Absence of rotation perception during warm water caloric irrigation in some seniors with postural instability

    OpenAIRE

    Elodie eChiarovano; Pierre-Paul eVidal; Christophe eMagnani; Georges eLamas; Ian S Curthoys; Catherine eDe Waele; Catherine eDe Waele

    2016-01-01

    Falls in seniors are a major public health problem. Falls lead to fear of falling, reduced mobility and decreased quality of life. Vestibular dysfunction is one of the fall risk factors. The relationship between objective measures of vestibular responses and age has been studied. However, the effects of age on vestibular perception during caloric stimulation have not been studied.Twenty senior subjects were included in the study separated in two groups: 10 seniors reporting postural instabili...

  9. Absence of Rotation Perception during Warm Water Caloric Irrigation in Some Seniors with Postural Instability

    OpenAIRE

    Chiarovano, Elodie; Vidal, Pierre-Paul; Magnani, Christophe; Lamas, Georges; Curthoys, Ian S.; de Waele, Catherine

    2016-01-01

    Falls in seniors are a major public health problem. Falls lead to fear of falling, reduced mobility, and decreased quality of life. Vestibular dysfunction is one of the fall risk factors. The relationship between objective measures of vestibular responses and age has been studied. However, the effects of age on vestibular perception during caloric stimulation have not been studied. Twenty senior subjects were included in the study, and separated in two groups: 10 seniors reporting postural in...

  10. Face Piercing (Body Art): Choosing Pleasure vs. Possible Pain and Posture Instability

    Science.gov (United States)

    Matheron, Eric; Kapoula, Zoï

    2011-01-01

    Piercings (body art, i.e., with jewelry) are more and more widespread. They can induce various complications such as infections, allergies, headaches, and various skin, cartilage, or dental problems, and represent a public health problem. We draw attention to possible side effects resulting from face piercing complications observed on four young adults such as eye misalignment, decreased postural control efficiency, and non-specific chronic back pain with associated comorbidity. We found that the origin was pierced jewelry on the face. Removing the jewelry restored eye alignment, improved postural control, and alleviated back pain in a lasting way. We suggest that pierced facial jewelry can disturb somaesthetic signals driven by the trigeminal nerve, and thus interfere with central integration processes, notably in the cerebellum and the vestibular nucleus involved in postural control and eye alignment. Facial piercings could induce sensory–motor conflict, exacerbate, or precipitate a pre-existing undetermined conflict, which leads pain and complaints. These findings are significant for health; further investigations would be of interest. PMID:21960975

  11. Locomotor Adaptation Improves Balance Control, Multitasking Ability and Reduces the Metabolic Cost of Postural Instability

    Science.gov (United States)

    Bloomberg, J. J.; Peters, B. T.; Mulavara, A. P.; Brady, R. A.; Batson, C. D.; Miller, C. A.; Ploutz-Snyder, R. J.; Guined, J. R.; Buxton, R. E.; Cohen, H. S.

    2011-01-01

    During exploration-class missions, sensorimotor disturbances may lead to disruption in the ability to ambulate and perform functional tasks during the initial introduction to a novel gravitational environment following a landing on a planetary surface. The overall goal of our current project is to develop a sensorimotor adaptability training program to facilitate rapid adaptation to these environments. We have developed a unique training system comprised of a treadmill placed on a motion-base facing a virtual visual scene. It provides an unstable walking surface combined with incongruent visual flow designed to enhance sensorimotor adaptability. Greater metabolic cost incurred during balance instability means more physical work is required during adaptation to new environments possibly affecting crewmembers? ability to perform mission critical tasks during early surface operations on planetary expeditions. The goal of this study was to characterize adaptation to a discordant sensory challenge across a number of performance modalities including locomotor stability, multi-tasking ability and metabolic cost. METHODS: Subjects (n=15) walked (4.0 km/h) on a treadmill for an 8 -minute baseline walking period followed by 20-minutes of walking (4.0 km/h) with support surface motion (0.3 Hz, sinusoidal lateral motion, peak amplitude 25.4 cm) provided by the treadmill/motion-base system. Stride frequency and auditory reaction time were collected as measures of locomotor stability and multi-tasking ability, respectively. Metabolic data (VO2) were collected via a portable metabolic gas analysis system. RESULTS: At the onset of lateral support surface motion, subj ects walking on our treadmill showed an increase in stride frequency and auditory reaction time indicating initial balance and multi-tasking disturbances. During the 20-minute adaptation period, balance control and multi-tasking performance improved. Similarly, throughout the 20-minute adaptation period, VO2 gradually

  12. A new approach of the Star Excursion Balance Test to assess dynamic postural control in people complaining from chronic ankle instability.

    Science.gov (United States)

    Pionnier, Raphaël; Découfour, Nicolas; Barbier, Franck; Popineau, Christophe; Simoneau-Buessinger, Emilie

    2016-03-01

    The purpose of this study was to quantitatively and qualitatively assess dynamic balance with accuracy in individuals with chronic ankle instability (CAI). To this aim, a motion capture system was used while participants performed the Star Excursion Balance Test (SEBT). Reached distances for the 8 points of the star were automatically computed, thereby excluding any dependence to the experimenter. In addition, new relevant variables were also computed, such as absolute time needed to reach each distance, lower limb ranges of motion during unipodal stance, as well as absolute error of pointing. Velocity of the center of pressure and range of variation of ground reaction forces have also been assessed during the unipodal phase of the SEBT thanks to force plates. CAI group exhibited smaller reached distances and greater absolute error of pointing than the control group (p<0.05). Moreover, the ranges of motion of lower limbs joints, the velocity of the center of pressure and the range of variation of the ground reaction forces were all significantly smaller in the CAI group (p<0.05). These reduced quantitative and qualitative performances highlighted a lower dynamic postural control. The limited body movements and accelerations during the unipodal stance in the CAI group could highlight a protective strategy. The present findings could help clinicians to better understand the motor strategies used by CAI patients during dynamic balance and may guide the rehabilitation process. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Experimental observation of the stratified electrothermal instability on aluminum with thickness greater than a skin depth

    Science.gov (United States)

    Hutchinson, T. M.; Awe, T. J.; Bauer, B. S.; Yates, K. C.; Yu, E. P.; Yelton, W. G.; Fuelling, S.

    2018-05-01

    A direct observation of the stratified electrothermal instability on the surface of thick metal is reported. Aluminum rods coated with 70 μ m Parylene-N were driven to 1 MA in 100 ns , with the metal thicker than the skin depth. The dielectric coating suppressed plasma formation, enabling persistent observation of discrete azimuthally correlated stratified thermal perturbations perpendicular to the current whose wave numbers, k , grew exponentially with rate γ (k ) =0.06 n s-1-(0.4 n s-1μ m2ra d-2 ) k2 in ˜1 g /c m3 , ˜7000 K aluminum.

  14. Experimental Observation of the Stratified Electrothermal Instability on Aluminum with Thickness Greater than a Skin Depth

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, Trevor M. [Univ. of Nevada, Reno, NV (United States); Hutchinson, Trevor M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Awe, Thomas James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bauer, Bruno S. [Univ. of Nevada, Reno, NV (United States); Yates, Kevin [Univ. of New Mexico, Albuquerque, NM (United States); Yu, Edmund p. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yelton, William G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fuelling, Stephan [Univ. of Nevada, Reno, NV (United States)

    2017-07-01

    The first direct observation of the stratified electrothermal instability on the surface of thick metal is reported. Aluminum rods coated with 70 μm Parylene-N were driven to 1 MA in approximately 100 ns, with the metal thicker than the skin depth. The dielectric coating suppressed plasma formation, enabling persistent observation of discrete azimuthally-correlated stratified structures perpendicular to the current. Strata amplitudes grow rapidly, while their Fourier spectrum shifts toward longer wavelength. Assuming blackbody emission, radiometric calculations indicate strata are temperature perturbations that grow exponentially with rate γ = 0.04 ns -1 in 3000- 10,000 K aluminum.

  15. The Effect of Joint Mobilization on Dynamic Postural Control in Patients With Chronic Ankle Instability: A Critically Appraised Topic.

    Science.gov (United States)

    Kosik, Kyle B; Gribble, Phillip A

    2018-01-01

    Clinical Scenario: Dorsiflexion range of motion is an important factor in the performance of the Star Excursion Balance Test (SEBT). While patients with chronic ankle instability (CAI) commonly experience decreased reach distances on the SEBT, ankle joint mobilization has been suggested to be an effective therapeutic intervention for targeting dorsiflexion range of motion. What is the evidence to support ankle joint mobilization for improving performance on the SEBT in patients with CAI? Summary of Key Findings: The literature was searched for articles examining the effects of ankle joint mobilization on scores of the SEBT. A total of 3 peer-reviewed articles were retrieved, 2 prospective individual cohort studies and 1 randomized controlled trial. Only 2 articles demonstrated favorable results following 6 sessions of ankle joint mobilization. Clinical Bottom Line: Despite the mixed results, the majority of the available evidence suggests that ankle joint mobilization improves dynamic postural control. Strength of Recommendation: In accordance with the Centre of Evidence Based Medicine, the inconsistent results and the limited high-quality studies indicate that there is level C evidence to support the use of ankle joint mobilization to improve performance on the SEBT in patients with CAI.

  16. The Neural Basis of Postural Instability Gait Disorder Subtype of Parkinson's Disease: A PET and fMRI Study.

    Science.gov (United States)

    Zhang, Li; Li, Tian-Nv; Yuan, Yong-Sheng; Jiang, Si-Ming; Tong, Qing; Wang, Min; Wang, Jian-Wei; Chen, Hua-Jun; Ding, Jian; Xu, Qin-Rong; Zhang, Ke-Zhong

    2016-05-01

    The aim of this study is to further uncover the neural basis of postural instability gait disorder (PIGD) subtype of Parkinson's disease. With F-18 fluorodeoxyglucose PET (FDG-PET), brain glucose metabolism of patients with PIGD (n = 15) was compared with healthy controls (n = 17) and tremor-dominant (TD) patients (n = 15), and the correlation between metabolism and PIGD symptoms was also assessed. Within PIGD symptom-correlated hypometabolic areas, the relationship of functional connectivity (FC) with motor and cognitive symptoms was examined by using functional MRI. Compared with controls, patients with PIGD displayed a distributed pattern of brain hypometabolism including striatal, frontal, and parietal areas. Relative to the pattern of TD patients, the pattern of patients with PIGD had additional metabolic decreases in caudate and inferior parietal lobule (IPL, Brodmann area [BA] 40). In PIGD group, the metabolic reductions in IPL (BA 40), middle frontal gyrus (MFG, BA 9) and fusiform gyrus (FG, BA 20) were associated with severe PIGD symptoms. Regions showing such correlation were chosen for further seed-based FC analysis. Decreased FC within the prefrontal-parietal network (between the MFG and IPL) was associated with severe PIGD symptoms. The involvement of the caudate, FG, and prefrontal-parietal network may be associated with the prominent gait impairments of PIGD subtype. Our findings expand the pathophysiological knowledge of PIGD subtype and provide valuable information for potential neuromodulation therapies alleviating gait disorders. © 2016 John Wiley & Sons Ltd.

  17. Executive Function and Postural Instability in People with Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Dong Xu

    2014-01-01

    Full Text Available The specific aspects of cognition contributing to balance and gait have not been clarified in people with Parkinson’s disease (PD. Twenty PD participants and twenty age- and gender-matched healthy controls were assessed on cognition and clinical mobility tests. General cognition was assessed with the Mini Mental State Exam and Addenbrooke’s Cognitive Exam. Executive function was evaluated using the Trail Making Tests (TMT-A and TMT-B and a computerized cognitive battery which included a series of choice reaction time (CRT tests. Clinical gait and balance measures included the Tinetti, Timed Up & Go, Berg Balance, and Functional Reach tests. PD participants performed significantly worse than the controls on the tests of cognitive and executive function, balance, and gait. PD participants took longer on Trail Making Tests, CRT-Location, and CRT-Colour (inhibition response. Furthermore, executive function, particularly longer times on CRT-Distracter and greater errors on the TMT-B, was associated with worse balance and gait performance in the PD group. Measures of general cognition were not associated with balance and gait measures in either group. For PD participants, attention and executive function were impaired. Components of executive function, particularly those involving inhibition response and distracters, were associated with poorer balance and gait performance in PD.

  18. Effects of reduced plantar cutaneous sensation on static postural control in individuals with and without chronic ankle instability.

    Science.gov (United States)

    Song, Kyeongtak; Kang, Tae Kyu; Wikstrom, Erik A; Jun, Hyung-Pil; Lee, Sae Yong

    2017-10-01

    The purpose of this study was to determine how reduced plantar cutaneous sensation influences static postural control in individuals with and without CAI. A case-control study design. Twenty-six individuals with self-reported CAI and 26 matched healthy controls participated in this study. The plantar aspect of the participants' foot was then submersed in ice water (0°C) for 10min to reduce plantar sensation. Before and after the cooling procedure, plantar cutaneous sensation thresholds and single leg balance with eyes open and closed were assessed. Significantly, higher scores were observed in both groups after ice water submersion (ppostural control improvement in both groups post-cooling. In single limb balance with eyes closed, Group×Intervention interactions were observed for the TTB AP mean (p=0.003) and TTB AP SD (p=0.017); indicating postural control deficits in CAI group post-cooling, but no changes in the control group. The main finding of this study was that reduced plantar cutaneous sensation induced by an ice submersion procedure caused eyes closed postural control impairments in those with CAI but not healthy controls. The present investigation demonstrated that the ability to dynamically reweight among sensory inputs to maintain postural stability appears to be diminished in CAI patients compared to healthy controls. Copyright © 2016. Published by Elsevier Ltd.

  19. White matter hyperintensities in Parkinson's disease: do they explain the disparity between the postural instability gait difficulty and tremor dominant subtypes?

    Directory of Open Access Journals (Sweden)

    Talia Herman

    Full Text Available BACKGROUND: Brain white matter hyperintensities (WMHs commonly observed on brain imaging of older adults are associated with balance and gait impairment and have also been linked to cognitive deficits. Parkinson's disease (PD is traditionally sub-classified into the postural instability gait difficulty (PIGD sub-type, and the tremor dominant (TD sub-type. Considering the known association between WMHs and axial symptoms like gait disturbances and postural instability, one can hypothesize that WMHs might contribute to the disparate clinical sub-types of patients with PD. METHODS: 110 patients with PD underwent a clinical evaluation and a 3T MRI exam. Based on the Unified Parkinson Disease Rating Scale, the patients were classified into motor sub-types, i.e., TD or PIGD, and scores reflecting PIGD and TD symptoms were computed. We compared white matter burden using three previously validated methods: one using a semi-quantitative visual rating scale in specific brain regions and two automated methods. RESULTS: Overall, MRI data were obtained in 104 patients. The mean WMHs scores and the percent of subjects with lesions in specific brain regions were similar in the two subtypes, p = 0.678. The PIGD and the TD scores did not differ even when comparing patients with a relatively high burden of WMHs to patients with a relatively low burden. Across most of the brain regions, mild to moderate correlations between WMHs and age were found (r = 0.23 to 0.41; p<0.021. Conversely, no significant correlations were found between WMHs and the PIGD score or disease duration. In addition, depressive symptoms and cerebro-vascular risk factors were similar among the two subtypes. CONCLUSIONS: In contrast to what has been reported previously among older adults, the present study could not demonstrate any association between WMHs and the PIGD or TD motor sub-types in patients with PD.

  20. The effect of perindopril on postural instability in older people with a history of falls-a randomised controlled trial.

    Science.gov (United States)

    Sumukadas, Deepa; Price, Rosemary; McMurdo, Marion E T; Rauchhaus, Petra; Struthers, Allan; McSwiggan, Stephen; Arnold, Graham; Abboud, Rami; Witham, Miles

    2018-01-01

    double-blind, parallel group, placebo-controlled randomised trial. we recruited people aged >65 years with at least one fall in the previous year. Participants received 4 mg perindopril or placebo daily for 15 weeks. The primary outcome was the between-group difference in force-plate measured anteroposterior (AP) sway at 15 weeks. Secondary outcomes included other measures of postural sway, limits of stability during maximal forward, right and left leaning, blood pressure, muscle strength, 6-min walk distance and falls. The primary outcome was assessed using two-way ANOVA, adjusted for baseline factors. we randomised 80 participants. Mean age was 78.0 (SD 7.4) years; 60 (75%) were female. About 77/80 (96%) completed the trial. At 15 weeks there were no significant between-group differences in AP sway with eyes open (mean difference 0 mm, 95% CI -8 to 7 mm, P = 0.91) or eyes closed (mean difference 2 mm, 95% CI -7 to 12 mm, P = 0.59); no differences in other measures of postural stability, muscle strength or function. About 16/40 (42%) of patients in each group had orthostatic hypotension at follow-up. The median number (IQR) of falls was 1 (0,4) in the perindopril versus 1 (0,2) in the placebo group (P = 0.24). perindopril did not improve postural sway in older people at risk of falls. ISRCTN58995463. © The Author 2017. Published by Oxford University Press on behalf of the British Geriatrics Society.

  1. Immediate effects of the suboccipital muscle inhibition technique in craniocervical posture and greater occipital nerve mechanosensitivity in subjects with a history of orthodontia use: a randomized trial.

    Science.gov (United States)

    Heredia Rizo, Alberto M; Pascual-Vaca, Ángel Oliva; Cabello, Manuel Albornoz; Blanco, Cleofás Rodríguez; Pozo, Fernando Piña; Carrasco, Antonio Luque

    2012-07-01

    The purpose of this study was to measure the immediate differences in craniocervical posture and pressure pain threshold of the greater occipital (GO) nerve in asymptomatic subjects with a history of having used orthodontics, after intervention by a suboccipital muscle inhibition (SMI) technique. This was a randomized, single-blind, clinical study with a sample of 24 subjects (21±1.78 years) that were divided into an experimental group (n=12) who underwent the SMI technique and a sham group (n=12) who underwent a sham (placebo) intervention. The sitting and standing craniovertebral angle and the pressure pain threshold of the GO nerve in both hemispheres were measured. The between-group comparison of the sample indicated that individuals subjected to the SMI technique showed a statistically significant increase in the craniovertebral angle in both the sitting (P<.001, F1,22=102.09, R2=0.82) and the standing (P<.001, F1,22=21.42, R2=0.56) positions and in the GO nerve pressure pain threshold in the nondominant hemisphere (P=.014, F1,22=7.06, R2=0.24). There were no statistically significant differences observed for the GO nerve mechanosensitivity in the dominant side (P=.202). Suboccipital muscle inhibition technique immediately improved the position of the head with the subject seated and standing, the clinical effect size being large in the former case. It also immediately decreased the mechanosensitivity of the GO nerve in the nondominant hemisphere, although the effect size was small. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

  2. Genomic instability in mice is greater in Fanconi anemia caused by deficiency of Fancd2 than Fancg.

    Science.gov (United States)

    Reliene, Ramune; Yamamoto, Mitsuko L; Rao, P Nagesh; Schiestl, Robert H

    2010-12-01

    Fanconi anemia (FA) results from mutations in the FANC genes and is characterized by bone marrow failure, birth defects, and a high incidence of cancer. FANCG is a part of the FA core complex that is responsible for monoubiquitination of FANCD2 and FANCI. The precise role of the FA pathway is not well understood, although it may be involved in homologous recombination (HR), nonhomologous end joining, and translesion synthesis (TLS). Fancd2(-/-) mice have a more severe phenotype than Fancg(-/-), and other FA core complex-deficient mice, although both Fancg and Fancd2 belong to the same FA pathway. We hypothesized that Fancd2 deficiency results in a more severe phenotype because Fancd2 also has a FA pathway-independent function in the maintenance of genomic integrity. To test this hypothesis, we determined the level of DNA damage and genomic instability in Fancd2(-/-), Fancg(-/-), and wild-type controls. Fancd2(-/-) mice displayed a higher magnitude of chromosomal breakage and micronucleus formation than the wild-type or Fancg(-/-) mice. Also, DNA strand breaks were increased in Fancd2(-/-) but not in Fancg(-/-) mice. In addition, Fancd2(-/-) mice displayed an elevated frequency of DNA deletions, resulting from HR at the endogenous p(un) locus. In contrast, in Fancg(-/-) mice, the frequency of DNA deletions was decreased. Thus, Fancd2 but not Fancg deficiency results in elevated chromosomal/DNA breakage and permanent genome rearrangements. This provides evidence that Fancd2 plays an additional role in the maintenance of genomic stability than Fancg, which might explain the higher predisposition to cancer seen in the Fancd2(-/-) mice.

  3. The role of Postural instability/gait difficulty and Fear of falling in predicting falls in non-demented older adults

    Science.gov (United States)

    Allali, Gilles; Ayers, Emmeline I.; Holtzer, Roee; Verghese, Joe

    2016-01-01

    Introduction Postural instability/gait difficulty (PIGD) and fear of falling (FoF) frequently co-exist, but their individual predictive values for falls have not been compared in aging. This study aims to determine both independent and combined effect of PIGD and FoF to falls in older adults without dementia. Methods PIGD and other extrapyramidal signs were systematically assessed in 449 community-dwelling participants without Parkinson’s disease (76.48 ± 6.61 ys; 56.8% female) enrolled in this longitudinal cohort study. Presence of FoF was measured by a single-item question (Do you have a FoF?) and self-confidence by the Activities-specific Balance Confidence scale (ABC scale). Results One hundred sixty-nine participants (38 %) had an incident fall over a mean follow-up of 20.1 ± 12.2 months. PIGD was present in 32% and FoF in 23% of the participants. Both PIGD (adjusted hazard ratio (aHR): 2.28; p = 0.016) and self-confidence (aHR: 0.99; p = 0.040) predicted falls when entered simultaneously in the Cox model. However, presence of FoF (aHR: 1.99; p = 0.021) and self-confidence (aHR: 0.98; p = 0.006) predicted falls only in individuals with PIGD. Conclusions PIGD and FoF were associated with future falls in older adults without dementia but FoF was a fall’s predictor only in individuals with PIGD. PMID:27866086

  4. Different patterns of spontaneous brain activity between tremor-dominant and postural instability/gait difficulty subtypes of Parkinson's disease: a resting-state fMRI study.

    Science.gov (United States)

    Chen, Hui-Min; Wang, Zhi-Jiang; Fang, Jin-Ping; Gao, Li-Yan; Ma, Ling-Yan; Wu, Tao; Hou, Ya-Nan; Zhang, Jia-Rong; Feng, Tao

    2015-10-01

    Postural instability/gait difficulty (PIGD) and tremor-dominant (TD) subtypes of Parkinson's disease (PD) show different clinical manifestations; however, their underlying neural substrates remain incompletely understood. This study aimed at investigating the subtype-specific patterns of spontaneous brain activity in PD. Thirty-one patients with PD (12 TD/19 PIGD) and 22 healthy gender- and age-matched controls were recruited. Resting-state functional magnetic resonance imaging data were collected, and amplitude of low-frequency fluctuations (ALFF) was measured. Voxelwise one-way analysis of covariance and post hoc analyses of ALFF were performed among the three groups, with age and gender as covariates (levodopa daily dosage and gray matter volume as additional covariates for validation analysis). Correlations of clinical variables (e.g., disease duration and PIGD/tremor subscale score) with ALFF values were examined. Compared with controls, patients with TD exhibited higher ALFF in the right cerebellar posterior lobe and patients with PIGD exhibited lower ALFF in the bilateral putamen and cerebellar posterior lobe, and higher values primarily in several cortical areas including the inferior and superior temporal gyrus, superior frontal, and parietal gyrus. Compared with patients with PIGD, patients with TD had higher ALFF in the bilateral putamen and the cerebellar posterior lobe, as well as lower ALFF in the bilateral temporal gyrus and the left superior parietal lobule. In all patients, ALFF in the bilateral cerebellar posterior lobe positively correlated with tremor score and ALFF in the bilateral putamen negatively correlated with PIGD score. Different patterns of spontaneous neural activity in the cerebellum and putamen may underlie the neural substrate of PD motor subtypes. © 2015 John Wiley & Sons Ltd.

  5. Impact of soft and hard insole density on postural stability in older adults.

    Science.gov (United States)

    Losa Iglesias, Marta Elena; Becerro de Bengoa Vallejo, Ricardo; Palacios Peña, Domingo

    2012-01-01

    A significant predictor of falls in the elderly population is attributed to postural instability. Thus, it is important to identify and implement practical clinical interventions to enhance postural stability in older adults. Shoe insoles have been identified as a mechanism to enhance postural control, and our study aimed to evaluate the impact of 2 shoe insoles on static standing balance in healthy, older adults compared with standing posture while barefoot. We hypothesized that both hard and soft shoe insoles would decrease postural sway compared with the barefoot condition. Indeed, excursion distances and sway areas were reduced, and sway velocity was decreased when wearing insoles. The hard insole was also effective when visual feedback was removed, suggesting that the more rigid an insole, the greater potential reduction in fall risk. Thus, shoe insoles may be a cost-effective, clinical intervention that is easy to implement to reduce the risk of falling in the elderly population. Copyright © 2012 Mosby, Inc. All rights reserved.

  6. Gait, posture and cognition in Parkinson's disease

    OpenAIRE

    Barbosa, Alessandra Ferreira; Chen, Janini; Freitag, Fernanda; Valente, Debora; Souza, Carolina de Oliveira; Voos, Mariana Callil; Chien, Hsin Fen

    2016-01-01

    ABSTRACT Gait disorders and postural instability are the leading causes of falls and disability in Parkinson's disease (PD). Cognition plays an important role in postural control and may interfere with gait and posture assessment and treatment. It is important to recognize gait, posture and balance dysfunctions by choosing proper assessment tools for PD. Patients at higher risk of falling must be referred for rehabilitation as early as possible, because antiparkinsonian drugs and surgery do n...

  7. Three-dimensional evaluation of postural stability in Parkinson's disease with mobile technology.

    Science.gov (United States)

    Ozinga, Sarah J; Koop, Mandy Miller; Linder, Susan M; Machado, Andre G; Dey, Tanujit; Alberts, Jay L

    2017-01-01

    Postural instability is a hallmark of Parkinson's disease. Objective metrics to characterize postural stability are necessary for the development of treatment algorithms to aid in the clinical setting. The aim of this project was to validate a mobile device platform and resultant three-dimensional balance metric that characterizes postural stability. A mobile Application was developed, in which biomechanical data from inertial sensors within a mobile device were processed to characterize movement of center of mass in the medial-lateral, anterior-posterior and trunk rotation directions. Twenty-seven individuals with Parkinson's disease and 27 age-matched controls completed various balance tasks. A postural stability metric quantifying the amplitude (peak-to-peak) of sway acceleration in each movement direction was compared between groups. The peak-to-peak value in each direction for each individual with Parkinson's disease across all trials was expressed as a normalized value of the control data to identify individuals with severe postural instability, termed Cleveland Clinic-Postural Stability Index. In all conditions, the balance metric for peak-to-peak was significantly greater in Parkinson's disease compared to controls (p mobile device sensors, provides a rapid and systematic metric for quantifying postural stability in Parkinson's disease.

  8. Gait, posture and cognition in Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Alessandra Ferreira Barbosa

    Full Text Available ABSTRACT Gait disorders and postural instability are the leading causes of falls and disability in Parkinson's disease (PD. Cognition plays an important role in postural control and may interfere with gait and posture assessment and treatment. It is important to recognize gait, posture and balance dysfunctions by choosing proper assessment tools for PD. Patients at higher risk of falling must be referred for rehabilitation as early as possible, because antiparkinsonian drugs and surgery do not improve gait and posture in PD.

  9. Postural stability in the elderly during sensory perturbations and dual tasking: the influence of refractive blur.

    Science.gov (United States)

    Anand, Vijay; Buckley, John G; Scally, Andy; Elliott, David B

    2003-07-01

    To determine the influence of refractive blur on postural stability during somatosensory and vestibular system perturbation and dual tasking. Fifteen healthy, elderly subjects (mean age, 71 +/- 5 years), who had no history of falls and had normal vision, were recruited. Postural stability during standing was assessed using a force platform, and was determined as the root mean square (RMS) of the center of pressure (COP) signal in the anterior-posterior (A-P) and medial-lateral directions collected over a 30-second period. Data were collected under normal standing conditions and with somatosensory and vestibular system perturbations. Measurements were repeated with an additional physical and/or cognitive task. Postural stability was measured under conditions of binocular refractive blur of 0, 1, 2, 4, and 8 D and with eyes closed. The data were analyzed with a population-averaged linear model. The greatest increases in postural instability were due to disruptions of the somatosensory and vestibular systems. Increasing refractive blur caused increasing postural instability, and its effect was greater when the input from the other sensory systems was disrupted. Performing an additional cognitive and physical task increased A-P RMS COP further. All these detrimental effects on postural stability were cumulative. The findings highlight the multifactorial nature of postural stability and indicate why the elderly, many of whom have poor vision and musculoskeletal and central nervous system degeneration, are at greater risk of falling. The findings also highlight that standing instability in both normal and perturbed conditions was significantly increased with refractive blur. Correcting visual impairment caused by uncorrected refractive error could be a useful intervention strategy to help prevent falls and fall-related injuries in the elderly.

  10. 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.

  11. Postural stability changes in the elderly with cataract simulation and refractive blur.

    Science.gov (United States)

    Anand, Vijay; Buckley, John G; Scally, Andy; Elliott, David B

    2003-11-01

    To determine the influence of cataractous and refractive blur on postural stability and limb-load asymmetry (LLA) and to establish how postural stability changes with the spatial frequency and contrast of the visual stimulus. Thirteen elderly subjects (mean age, 70.76 +/- 4.14 [SD] years) with no history of falls and normal vision were recruited. Postural stability was determined as the root mean square [RMS] of the center of pressure (COP) signal in the anterior-posterior (A-P) and medial-lateral directions and LLA was determined as the ratio of the average body weight placed on the more-loaded limb to the less-loaded limb, recorded during a 30-second period. Data were collected under normal standing conditions and with somatosensory system input disrupted. Measurements were repeated with four visual targets with high (8 cyc/deg) or low (2 cyc/deg) spatial frequency and high (Weber contrast, approximately 95%) or low (Weber contrast, approximately 25%) contrast. Postural stability was measured under conditions of binocular refractive blur of 0, 1, 2, 4, and 8 D and with cataract simulation. The data were analyzed in a population-averaged linear model. The cataract simulation caused significant increases in postural instability equivalent to that caused by 8-D blur conditions, and its effect was greater when the input from the somatosensory system was disrupted. High spatial frequency targets increased postural instability. Refractive blur, cataract simulation, or eye closure had no effect on LLA. Findings indicate that cataractous and refractive blur increase postural instability, and show why the elderly, many of whom have poor vision along with musculoskeletal and central nervous system degeneration, are at greater risk of falling. Findings also highlight that changes in contrast sensitivity rather than resolution changes are responsible for increasing postural instability. Providing low spatial frequency information in certain environments may be useful in

  12. Postural ortostatisk takykardisyndrom

    DEFF Research Database (Denmark)

    Brinth, Louise; Pors, Kirsten; Mehlsen, Jesper

    2014-01-01

    Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous condition of dysautonomia and suspected autoimmunity characterized by abnormal increments in heart rate upon assumption of the upright posture accompanied by symptoms of cerebral hypoperfusion and sympathoexcitation. An increase...... in heart rate equal to or greater than 30 bpm or to levels higher than 120 bpm during a head-up tilt test is the main diagnostic criterion. Management includes both non-pharmacological and pharmacological treatment focusing on stress management, volume expansion and heart rate control....

  13. The Interaction between Visual and Proprioception Information for Dynamic Postural Control in Healthy Individuals

    Directory of Open Access Journals (Sweden)

    yasin hoseini

    2017-06-01

    Conclusion: the posture is controled mostly by the motion in the knee joint rather than the hip or ankle joints. It is recommended to enhance the knee extensors to prevent falling in people with high risk of postural instability.

  14. The Effect of 2 Forms of Talocrural Joint Traction on Dorsiflexion Range of Motion and Postural Control in Those With Chronic Ankle Instability.

    Science.gov (United States)

    Powden, Cameron J; Hogan, Kathleen K; Wikstrom, Erik A; Hoch, Matthew C

    2017-05-01

    Talocrural joint mobilizations are commonly used to address deficits associated with chronic ankle instability (CAI). Examine the immediate effects of talocrural joint traction in those with CAI. Blinded, crossover. Laboratory. Twenty adults (14 females; age = 23.80 ± 4.02 y; height = 169.55 ± 12.38 cm; weight = 78.34 ± 16.32 kg) with self-reported CAI participated. Inclusion criteria consisted of a history of ≥1 ankle sprain, ≥2 episodes of giving way in the previous 3 mo, answering "yes" to ≥4 questions on the Ankle Instability Instrument, and ≤24 on the Cumberland Ankle Instability Tool. Subjects participated in 3 sessions in which they received a single treatment session of sustained traction (ST), oscillatory traction (OT), or a sham condition in a randomized order. Interventions consisted of four 30-s sets of traction with 1 min of rest between sets. During ST and OT, the talus was distracted distally from the ankle mortise to the end-range of accessory motion. ST consisted of continuous distraction and OT involved 1-s oscillations between the mid and end-range of accessory motion. The sham condition consisted of physical contact without force application. Preintervention and postintervention measurements of weight-bearing dorsiflexion, dynamic balance, and static single-limb balance were collected. The independent variable was treatment (ST, OT, sham). The dependent variables included pre-to-posttreatment change scores for the WBLT (cm), normalized SEBTAR (%), and time-to-boundary (TTB) variables(s). Separate 1-way ANOVAs examined differences between treatments for each dependent variable. Alpha was set a priori at P manual therapies.

  15. 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.

  16. Posture and isokinetic shoulder strength in female water polo players

    African Journals Online (AJOL)

    Kathryn van Boom

    pathological injuries, such as rotator cuff tendinitis, shoulder instability and shoulder ... and specific postural characteristics, which will be useful in future studies. ... concentric and eccentric IR and ER shoulder muscle strength in 15 club-level ...

  17. Postural changes versus balance control and falls in community-living older adults: a systematic review

    Directory of Open Access Journals (Sweden)

    Viviane Lemos Silva Fernandes

    2018-06-01

    Full Text Available Abstract Introduction: Since falls are considered to be a public health problem, it is important to identify whether postural changes over time contribute to the risk of falls in older adults. Objective: To investigate whether postural changes increase fall risk and/or postural imbalance in healthy, community-dwelling older adults. Methods: In April 2016, two reviewers independently searched the PubMed, Web of Science, SPORTDiscus, and CINAHL databases for studies in English published in the previous 10 years, using the following combined keywords: “posture” or (“kyphosis”,“lumbar lordosis”,“flexed posture”,“spinal curvature”,“spinal sagittal contour” AND “elderly” AND “fall”. Study quality was assessed according to the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology guidelines for observational studies. Results: The search retrieved 1,734 articles. Only observational studies that assessed posture, balance, and/or falls in older adults were considered eligible for review. The final sample included 17 articles: reliability and reproducibility of the instruments were not reported in five studies, while two studies offered a questionable description of the instruments used. Fourteen articles analyzed postural changes at the trunk level and three articles assessed them at the ankles and feet. Most studies found a positive association between postural changes and an increased risk for loss of balance and falls. Conclusion: Thoracic hyperkyphosis, loss of lumbar lordosis, and decreased plantar arch seem to contribute to greater postural instability, and thus to a higher risk of falls in community-living older adults.

  18. Ehlers-Danlos Syndrome, Hypermobility Type: Impact of Somatosensory Orthoses on Postural Control (A Pilot Study

    Directory of Open Access Journals (Sweden)

    Emma G. Dupuy

    2017-06-01

    Full Text Available Elhers-Danlos syndrome (EDS is the clinical manifestation of connective tissue disorders, and comprises several clinical forms with no specific symptoms and selective medical examinations which result in a delay in diagnosis of about 10 years. The EDS hypermobility type (hEDS is characterized by generalized joint hypermobility, variable skin hyperextensibility and impaired proprioception. Since somatosensory processing and multisensory integration are crucial for both perception and action, we put forth the hypothesis that somatosensory deficits in hEDS patients may lead, among other clinical symptoms, to misperception of verticality and postural instability. Therefore, the purpose of this study was twofold: (i to assess the impact of somatosensory deficit on subjective visual vertical (SVV and postural stability; and (ii to quantify the effect of wearing somatosensory orthoses (i.e., compressive garments and insoles on postural stability. Six hEDS patients and six age- and gender-matched controls underwent a SVV (sitting, standing, lying on the right side evaluation and a postural control evaluation on a force platform (Synapsys, with or without visual information (eyes open (EO/eyes closed (EC. These two latter conditions performed either without orthoses, or with compression garments (CG, or insoles, or both. Results showed that patients did not exhibit a substantial perceived tilt of the visual vertical in the direction of the body tilt (Aubert effect as did the control subjects. Interestingly, such differential effects were only apparent when the rod was initially positioned to the left of the vertical axis (opposite the longitudinal body axis. In addition, patients showed greater postural instability (sway area than the controls. The removal of vision exacerbated this instability, especially in the mediolateral (ML direction. The wearing of orthoses improved postural stability, especially in the eyes-closed condition, with a particularly

  19. Postural ortostatisk takykardi-syndrom

    DEFF Research Database (Denmark)

    Brinth, Louise; Pors, Kirsten; Mehlsen, Jesper

    2015-01-01

    Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous condition of dysautonomia and suspected autoimmunity characterized by abnormal increments in heart rate upon assumption of the upright posture accompanied by symptoms of cerebral hypoperfusion and sympathoexcitation. An increase...... in heart rate equal to or greater than 30 bpm or to levels higher than 120 bpm during a head-up tilt test is the main diagnostic criterion. Management includes both non-pharmacological and pharmacological treatment focusing on stress management, volume expansion and heart rate control....

  20. Determining postural stability

    Science.gov (United States)

    Lieberman, Erez (Inventor); Forth, Katharine E. (Inventor); Paloski, William H. (Inventor)

    2011-01-01

    A method for determining postural stability of a person can include acquiring a plurality of pressure data points over a period of time from at least one pressure sensor. The method can also include the step of identifying a postural state for each pressure data point to generate a plurality of postural states. The method can include the step of determining a postural state of the person at a point in time based on at least the plurality of postural states.

  1. Interactions between posture and locomotion: motor patterns in humans walking with bent posture versus erect posture.

    Science.gov (United States)

    Grasso, R; Zago, M; Lacquaniti, F

    2000-01-01

    Human erect locomotion is unique among living primates. Evolution selected specific biomechanical features that make human locomotion mechanically efficient. These features are matched by the motor patterns generated in the CNS. What happens when humans walk with bent postures? Are normal motor patterns of erect locomotion maintained or completely reorganized? Five healthy volunteers walked straight and forward at different speeds in three different postures (regular, knee-flexed, and knee- and trunk-flexed) while their motion, ground reaction forces, and electromyographic (EMG) activity were recorded. The three postures imply large differences in the position of the center of body mass relative to the body segments. The elevation angles of the trunk, pelvis, and lower limb segments relative to the vertical in the sagittal plane, the ground reaction forces and the rectified EMGs were analyzed over the gait cycle. The waveforms of the elevation angles along the gait cycle remained essentially unchanged irrespective of the adopted postures. The first two harmonics of these kinematic waveforms explain >95% of their variance. The phase shift but not the amplitude ratio between the first harmonic of the elevation angle waveforms of adjacent pairs was affected systematically by changes in posture. Thigh, shank, and foot angles covaried close to a plane in all conditions, but the plane orientation was systematically different in bent versus erect locomotion. This was explained by the changes in the temporal coupling among the three segments. For walking speeds >1 m s(-1), the plane orientation of bent locomotion indicates a much lower mechanical efficiency relative to erect locomotion. Ground reaction forces differed prominently in bent versus erect posture displaying characteristics intermediate between those typical of walking and those of running. Mean EMG activity was greater in bent postures for all recorded muscles independent of the functional role. The waveforms

  2. Postural steadiness and ankle force variability in peripheral neuropathy

    Science.gov (United States)

    Paxton, Roger J.; Feldman-Kothe, Caitlin; Trabert, Megan K.; Hitchcock, Leah N.; Reiser, Raoul F.; Tracy, Brian L.

    2015-01-01

    Introduction The purpose was to determine the effect of peripheral neuropathy (PN) on motor output variability for ankle muscles of older adults, and the relation between ankle motor variability and postural stability in PN patients. Methods Older adults with (O-PN) and without PN (O), and young adults (Y) underwent assessment of standing postural stability and ankle muscle force steadiness. Results O-PN displayed impaired ankle muscle force control and postural stability compared with O and Y groups. For O-PN, the amplitude of plantarflexor force fluctuations was moderately correlated with postural stability under no-vision conditions (r = 0.54, P = 0.01). Discussion The correlation of variations in ankle force with postural stability in PN suggests a contribution of ankle muscle dyscontrol to the postural instability that impacts physical function for older adults with PN. PMID:26284897

  3. Kinematics of the human mandible for different head postures.

    Science.gov (United States)

    Visscher, C M; Huddleston Slater, J J; Lobbezoo, F; Naeije, M

    2000-04-01

    The influence of head posture on movement paths of the incisal point (IP) and of the mandibular condyles during free open-close movements was studied. Ten persons, without craniomandibular or cervical spine disorders, participated in the study. Open close mandibular movements were recorded with the head in five postures, viz., natural head posture, forward head posture, military posture, and lateroflexion to the right and to the left side, using the Oral Kinesiologic Analysis System (OKAS-3D). This study showed that in a military head posture, the opening movement path of the incisal point is shifted anteriorly relative to the path in a natural head posture. In a forward head posture, the movement path is shifted posteriorly whereas during lateroflexion, it deviates to the side the head has moved to. Moreover, the intra-articular distance in the temporomandibular joint during closing is smaller with the head in military posture and greater in forward head posture, as compared to the natural head posture. During lateroflexion, the intra-articular distance on the ipsilateral side is smaller. The influence of head posture upon the kinematics of the mandible is probably a manifestation of differences in mandibular loading in the different head postures.

  4. Guide to Good Posture

    Science.gov (United States)

    ... you are moving or still, can prevent pain, injuries, and other health problems. What is posture? Posture is how you hold your body. There are two types: Dynamic posture is how you hold yourself when you are moving, like when you are walking, running, or bending over to pick up something. Static ...

  5. Does increased postural threat lead to more conscious control of posture?

    Science.gov (United States)

    Huffman, J L; Horslen, B C; Carpenter, M G; Adkin, A L

    2009-11-01

    Although it is well established that postural threat modifies postural control, little is known regarding the underlying mechanism(s) responsible for these changes. It is possible that changes in postural control under conditions of elevated postural threat result from a shift to a more conscious control of posture. The purpose of this study was to determine the influence of elevated postural threat on conscious control of posture and to determine the relationship between conscious control and postural control measures. Forty-eight healthy young adults stood on a force plate at two different surface heights: ground level (LOW) and 3.2-m above ground level (HIGH). Centre of pressure measures calculated in the anterior-posterior (AP) direction were mean position (AP-MP), root mean square (AP-RMS) and mean power frequency (AP-MPF). A modified state-specific version of the Movement Specific Reinvestment Scale was used to measure conscious motor processing (CMP) and movement self-consciousness (MSC). Balance confidence, fear of falling, perceived stability, and perceived and actual anxiety indicators were also collected. A significant effect of postural threat was found for movement reinvestment as participants reported more conscious control and a greater concern about their posture at the HIGH height. Significant correlations between CMP and MSC with AP-MP were observed as participants who consciously controlled and were more concerned for their posture leaned further away from the platform edge. It is possible that changes in movement reinvestment can influence specific aspects of posture (leaning) but other aspects may be immune to these changes (amplitude and frequency).

  6. Postural control and functional balance in individuals with diabetic peripheral neuropathy

    Directory of Open Access Journals (Sweden)

    Ana Claudia de Souza Fortaleza

    2013-04-01

    Full Text Available Diabetic Peripheral Neuropathy (DPN brings on reduced somatosensation, which can lead to changes in postural control. The objective of this study was to evaluate postural control in a standing position and in different conditions, as well as functional balance in individuals with DPN, make the correlation between the results obtained from the postural control assessment with the values from the functional balance test and compare the results obtained in the neuropathy group with those of the control group, checking for possible differences between the evaluation conditions of both groups. The study included 13 women with DPN (NG and 17 non-diabetic women (CG. Postural control assessment was performed by kinemetry in the following conditions: eyes opened (EO, eyes closed (EC, and semi-tandem (ST. The data was processed in MATLAB and the following variables were generated: mean amplitude of oscillation (MAO in the anterior-posterior (AP and medial-lateral (ML direction; and average speed of oscillation (ASO in AP and ML direction. Functional balance was assessed by the Timed Up and Go Test. There was significant difference between the groups (p≤0.005 in MAO-AP EO and EC, MAO-ML EC and ST, and ASO-ML ST. There were differences between the conditions EO and ST (p≤0.005 and EC and ST (p≤0.005 for the variables MAO-ML and ASO-ML with greater damage to the NG, which also had a lower functional balance (p=0.001. ML instability was positively correlated with functional imbalance. The results show a change in the postural control system in the DPN, which could lead these individuals to a higher risk for falls and functional impairment.

  7. Postural control and functional balance in individuals with diabetic peripheral neuropathy

    Directory of Open Access Journals (Sweden)

    Ana Claudia de Souza Fortaleza

    2013-03-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2013v15n3p305 Diabetic Peripheral Neuropathy (DPN brings on reduced somatosensation, which can lead to changes in postural control. The objective of this study was to evaluate postural control in a standing position and in different conditions, as well as functional balance in individuals with DPN, make the correlation between the results obtained from the postural control assessment with the values from the functional balance test and compare the results obtained in the neuropathy group with those of the control group, checking for possible differences between the evaluation conditions of both groups. The study included 13 women with DPN (NG and 17 non-diabetic women (CG. Postural control assessment was performed by kinemetry in the following conditions: eyes opened (EO, eyes closed (EC, and semi-tandem (ST. The data was processed in MATLAB and the following variables were generated: mean amplitude of oscillation (MAO in the anterior-posterior (AP and medial-lateral (ML direction; and average speed of oscillation (ASO in AP and ML direction. Functional balance was assessed by the Timed Up and Go Test. There was significant difference between the groups (p≤0.005 in MAO-AP EO and EC, MAO-ML EC and ST, and ASO-ML ST. There were differences between the conditions EO and ST (p≤0.005 and EC and ST (p≤0.005 for the variables MAO-ML and ASO-ML with greater damage to the NG, which also had a lower functional balance (p=0.001. ML instability was positively correlated with functional imbalance. The results show a change in the postural control system in the DPN, which could lead these individuals to a higher risk for falls and functional impairment.

  8. Postural effects when cycling in late pregnancy.

    Science.gov (United States)

    O'Neill, Maureen E; Cooper, Karen A; Boyce, E Stewart; Hunyor, Stephen N

    2006-12-01

    This study assessed if upright cycling is preferable to semi-recumbent cycling during pregnancy. Healthy women with low risk singleton pregnancies were tested at 34-38 weeks gestation. They cycled for 12 min, either semi-recumbent (45 degrees, n = 27) or upright (n = 23), at 135-145 beats min(-1). When semi-recumbent, minute ventilation was greater (pposture-independent. All increased with exercise (p0.05). Small post-exercise fetal heart rate increases (by 8 beats min(-1), ppostures (n = 11 in each sub-group), with no adverse changes. Fetal heart rate accelerations and uterine activity (n = 11 in each sub-group) were not influenced by posture or exercise. (1) Neither posture had a distinct advantage. (2) Both postures were safe for short duration cycling. (3) The same target maternal heart rates are suitable for both postures because they resulted in similar oxygen consumptions and fetal heart rates.

  9. The Effect of Wearing Different Types of Respirators on Postural Stability and Comfort

    OpenAIRE

    Farhang Akbar-Khanzadeh; Sandra M. Woolley; Kent Huang

    2012-01-01

    Respirators are commonly used to protect workers against workplace airborne contaminants, but this equipment may become a safety hazard by creating discomfort, disorientation and postural instability.Although postural stability is critical to workers, especially those working near moving objects or on surfaces where a loss of balance may become life threatening, little attention has been given to the effect of respirators on wearers’ postural stability. The purpose of this study was to examin...

  10. Postural orientation : Age-related changes in variability and time-to-boundary

    NARCIS (Netherlands)

    Van Wegen, E. E.H.; Van Emmerik, R. E.A.; Riccio, G. E.

    2002-01-01

    The relation between age-specific postural instability and the detection of stability boundaries was examined. Balance control was investigated under different visual conditions (eyes open/closed) and postural orientations·(forward/backward lean) while standing on a force platform. Dependent

  11. Clinical working postures of bachelor of oral health students.

    Science.gov (United States)

    Horton, S J; Johnstone, C L; Hutchinson, C M W; Taylor, P A; Wade, K J

    2011-09-01

    To observe and describe the clinical working postures of final-year Bachelor of Oral Health (BOH) students. Pilot observational study. The University of Otago Faculty of Dentistry and School of Physiotherapy. Eight final-year BOH students voluntarily participated in this study, where postural data were collected using a digital video camera during a standard clinical treatment session. The postural data were analysed using 3D Match biomechanical software. Final-year BOH students who work in the seated position are exposed to neck flexion of greater than 35 degrees, together with trunk flexion greater than 20 degrees and bilateral elbow flexion greater than 90 degrees. The findings of this study agree with the findings of previous postural studies of dental professionals. Dental hygiene students, together with their clinical supervisors, need to be aware of the importance of good working posture early in their careers, and pay particular attention to the degree of neck flexion occurring for prolonged periods.

  12. Postural stability and occlusal status among Japanese elderly.

    Science.gov (United States)

    Song-Yu, Xuan; Rodis, Omar M M; Ogata, Sagiri; Can-Hu, Jin; Nishimura, Michiko; Matsumura, Seishi

    2012-06-01

    There are still no data available on the relationship between postural stability and occlusal status among the elderly. To examine relationships between postural stability and occlusal status through a cohort study among elderly Japanese. Oral examination, occlusal status, postural stability and a questionnaire were conducted and given to 87 community-dwelling Japanese at enrolment. The average occlusal pressure of the female group was statistically higher than the male group while average occlusal pressure and postural stability length were lesser in the group with more remaining teeth. Postural stability area and number of remaining teeth showed statistically significant correlations. Postural stability length was lesser in the group with strong occlusal force. Furthermore, the number of decayed teeth was fewer in the good hygiene group. This study identified a close relationship between occlusal status and postural stability of Japanese older individuals. Occlusal hypofunction was observed more in those with occlusal problems, and a decrease in their occlusal functions resulted in postural instability. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

  13. Changes in postural control in patients with Parkinson's disease: a posturographic study.

    Science.gov (United States)

    Doná, F; Aquino, C C; Gazzola, J M; Borges, V; Silva, S M C A; Ganança, F F; Caovilla, H H; Ferraz, H B

    2016-09-01

    Postural instability is one of the most disabling features in Parkinson's disease (PD), and often leads to falls that reduce mobility and functional capacity. The objectives of this study were to analyse the limit of stability (LOS) and influence of the manipulation of visual, somatosensorial and visual-vestibular information on postural control in patients with PD and healthy subjects. Cross-sectional. Movement Disorders Unit, university setting. Eighty-two subjects aged between 37 and 83 years: 41 with Parkinson's disease in the 'on' state and 41 healthy subjects with no neurological disorders. Both groups were matched in terms of sex and age. Unified Parkinson's Disease Rating Scale (UPDRS)-motor score, modified Hoehn and Yahr staging, Dynamic Gait Index (DGI) and posturography with integrated virtual reality. The parameters analysed by posturography were LOS area, area of body centre of pressure excursion and balance functional reserve in the standing position in 10 conditions (open and closed eyes, unstable surface with eyes closed, saccadic and optokinetic stimuli, and visual-vestibular interaction). The mean UPDRS motor score and DGI score were 27 [standard deviation (SD) 14] and 21 (SD 3), respectively. Thirteen participants scored between 0 and 19 points, indicating major risk of falls. Posturographic assessment showed that patients with PD had significantly lower LOS area and balance functional reserve values, and greater body sway area in all posturographic conditions compared with healthy subjects. Patients with PD have reduced LOS area and greater postural sway compared with healthy subjects. The deterioration in postural control was significantly associated with major risk of falls. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  14. [Posture and gait disorders and the incidence of falling in patients with Parkinson].

    Science.gov (United States)

    Cano-de la Cuerda, R; Macías-Jiménez, A I; Cuadrado-Pérez, M L; Miangolarra-Page, J C; Morales-Cabezas, M

    Although falls are one of the main causes of morbidity and mortality in patients with Parkinson's disease, studies about its incidence and predicting factors are scarce. Our study involved 25 patients with PD (15 males and 10 females; age: 75.8 +/- 6.5 years). A closed survey was used to determine a retrospective record of falls during the last year. An analysis was performed to examine whether there was a relationship with Hoehn and Yahr staging, the score on the Up and Go scale or the Barthel index and with possible risk factors for falls. All the patients had suffered falls at some time over the last year (mean number of falls: 6.5 +/- 3.8). 56% of the falls happened during the phases of the day when patient mobility was at its highest. A significant correlation was found between the number of falls and the Hoehn and Yahr and the Up and Go scores. The number of falls was significantly higher in patients with loss of postural reflexes, the need for help in order to walk, and blockage and festination phenomena. No association was found with fear of falling, visual alterations or postural lateralisation. Association with the Barthel index and dependence for activities of daily living reached almost significant levels. Postural instability and disorders affecting gait appear to be the factors that give patients with PD a greater propensity to fall. Patients who present such alterations should be submitted to rehabilitation therapy aimed at preventing them from falling.

  15. 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

  16. Assessing Somatosensory Utilization during Unipedal Postural Control.

    Science.gov (United States)

    Goel, Rahul; De Dios, Yiri E; Gadd, Nichole E; Caldwell, Erin E; Peters, Brian T; Reschke, Millard F; Bloomberg, Jacob J; Oddsson, Lars I E; Mulavara, Ajitkumar P

    2017-01-01

    Multisensory-visual, vestibular and somatosensory information is integrated for appropriate postural control. The primary goal of this study was to assess somatosensory utilization during a functional motor task of unipedal postural control, in normal healthy adults. Assessing individual bias in the utilization of individual sensory contributions during postural control may help customization of rehabilitation protocols. In this study, a test paradigm of unipedal stance control in supine orientation with and without vision was assessed. Postural control in this test paradigm was hypothesized to utilize predominantly contributions of somatosensory information from the feet and ankle joint, with minimal vestibular input. Fourteen healthy subjects "stood" supine on their dominant leg while strapped to a backpack frame that was freely moving on air-bearings, to remove available otolith tilt cues with respect to gravity that influences postural control when standing upright. The backpack was attached through a cable to a pneumatic cylinder that provided a gravity-like load. Subjects performed three trials each with Eyes-open (EO) and Eyes-closed (EC) while loaded with 60% body weight. There was no difference in unipedal stance time (UST) across the two conditions with EC condition challenging the postural control system greater than the EO condition. Stabilogram-diffusion analysis (SDA) indicated that the critical mean square displacement was significantly different between the two conditions. Vestibular cues, both in terms of magnitude and the duration for which relevant information was available for postural control in this test paradigm, were minimized. These results support our hypothesis that maintaining unipedal stance in supine orientation without vision, minimizes vestibular contribution and thus predominantly utilizes somatosensory information for postural control.

  17. Postural control and central motor pathway involvement in type 2 ...

    African Journals Online (AJOL)

    Logistic regression analysis showed peripheral neuropathy as the main factor implicated in postural instability in these patients. However, significant correlation was found between MEP amplitude and MCT composite score in patients without peripheral neuropathy. Conclusion: Although type 2 diabetic patients had ...

  18. Inefficient postural responses to unexpected slips during walking in older adults.

    Science.gov (United States)

    Tang, P F; Woollacott, M H

    1998-11-01

    Slips account for a high percentage of falls and subsequent injuries in community-dwelling older adults but not in young adults. This phenomenon suggests that although active and healthy older adults preserve a mobility level comparable to that of young adults, these older adults may have difficulty generating efficient reactive postural responses when they slip. This study tested the hypothesis that active and healthy older adults use a less effective reactive balance strategy than young adults when experiencing an unexpected forward slip occurring at heel strike during walking. This less effective balance strategy would be manifested by slower and smaller postural responses, altered temporal and spatial organization of the postural responses, and greater upper trunk instability after the slip. Thirty-three young adults (age range=19-34 yrs, mean=25+/-4 yrs) and 32 community-dwelling older adults (age range=70-87 yrs, mean=74+/-14 yrs) participated. Subjects walked across a movable forceplate which simulated a forward slip at heel strike. Surface electromyography was recorded from bilateral leg, thigh, hip, and trunk muscles. Kinematic data were collected from the right (perturbed) side of the body. Although the predominant postural muscles and the activation sequence of these muscles were similar between the two age groups, the postural responses of older adults were of longer onset latencies, smaller magnitudes, and longer burst durations compared to young adults. Older adults also showed a longer coactivation duration for the ankle, knee, and trunk agonist/antagonist pairs on the perturbed side and for the knee agonist/antagonist pair on the nonperturbed side. Behaviorally, older adults became less stable after the slips. This was manifested by a higher incidence of being tripped (21 trials in older vs 5 trials in young adults) and a greater trunk hyperextension with respect to young adults. Large arm elevation was frequently used by older adults to assist in

  19. Postural control and head stability during natural gaze behaviour in 6- to 12-year-old children.

    Science.gov (United States)

    Schärli, A M; van de Langenberg, R; Murer, K; Müller, R M

    2013-06-01

    We investigated how the influence of natural exploratory gaze behaviour on postural control develops from childhood into adulthood. In a cross-sectional design, we compared four age groups: 6-, 9-, 12-year-olds and young adults. Two experimental trials were performed: quiet stance with a fixed gaze (fixed) and quiet stance with natural exploratory gaze behaviour (exploratory). The latter was elicited by having participants watch an animated short film on a large screen in front of them. 3D head rotations in space and centre of pressure (COP) excursions on the ground plane were measured. Across conditions, both head rotation and COP displacement decreased with increasing age. Head movement was greater in the exploratory condition in all age groups. In all children-but not in adults-COP displacement was markedly greater in the exploratory condition. Bivariate correlations across groups showed highly significant positive correlations between COP displacement in ML direction and head rotation in yaw, roll, and pitch in both conditions. The regularity of COP displacements did not show a clear developmental trend, which indicates that COP dynamics were qualitatively similar across age groups. Together, the results suggest that the contribution of head movement to eye-head saccades decreases with age and that head instability-in part resulting from such gaze-related head movements-is an important limiting factor in children's postural control. The lack of head stabilisation might particularly affect children in everyday activities in which both postural control and visual exploration are required.

  20. 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.

  1. Kinematics in newly walking toddlers does not depend upon postural stability

    NARCIS (Netherlands)

    Ivanenko, Yuri P; Dominici, Nadia; Cappellini, Germana; Lacquaniti, Francesco

    When a toddler starts to walk without support, gait kinematics and electromyographic (EMG) activity differ from those of older children and the body displays considerable oscillations due to poor equilibrium. Postural instability clearly affects motor patterns in adults, but does instability explain

  2. Exercise and Posture

    Science.gov (United States)

    ... About Spondylitis › Treatment Information › Exercise & Posture Print Page Exercise Exercise is an integral part of any spondylitis ... For First Responders For Chiropractors Research Article Archive Exercise Guidelines Having an exercise program that accomplishes your ...

  3. Influence of pain on postural control in women with neck pain

    Directory of Open Access Journals (Sweden)

    Juliana Soares

    2013-04-01

    Full Text Available The objective of this study was to investigate the influence of pain on postural control in women with neck pain and the relationship with possible changes in sensory systems and posture. The neck pain group was composed of women, aged between 20 and 50years, complaining of neck pain for more than three months; the control group was composed of women without complaints of neck pain. For the characterization of the groups, we used anamnesis, neck disability index and Visual Analogue Scale. Postural balance was assessed on force platform. Postural balance with manipulation of the sensory systems was measured by Foam Laser Dynamic Posturography, exposing the individual to six sensory organization tests. Posture was assessed by the Postural Assessment Software. The normality of the variables were verified using Shapiro-Wilk test, Student’s t-test and Mann-Whitney test for comparison between groups, with a significance level of5%. Groups were homogeneous in demographic variables. We observed higher amplitude and displacement velocity of the center of pressure in the neck pain group, showing greater postural balance. There were significant diferences incraniovertebral angle, showing forward head posture in symptomatic women. In dynamics posturography, we observed a difference between the groups: the score obtainedin the six sensory conditions showed that neck pain group presented greater balance impairment. Neck pain and forward head posture have a deleterious effect on postural control in symptomatic women, both in the static posture and dynamic posture.

  4. Measuring postural control during mini-squat posture in men with early knee osteoarthritis.

    Science.gov (United States)

    Petrella, M; Gramani-Say, K; Serrão, P R M S; Lessi, G C; Barela, J A; Carvalho, R P; Mattiello, S M

    2017-04-01

    Studies have suggested a compromised postural control in individuals with knee osteoarthritis (OA) evidenced by larger and faster displacement of center of pressure (COP). However, quantification of postural control in the mini-squat posture performed by patients with early knee OA and its relation to muscle strength and self-reported symptoms have not been investigated. The main aim of this cross-sectional, observational, controlled study was to determine whether postural control in the mini-squat posture differs between individuals with early knee OA and a control group (CG) and verify the relation among knee extensor torque (KET) and self-reported physical function, stiffness and pain. Twenty four individuals with knee OA grades I and II (OAG) (mean age: 52.35±5.00) and twenty subjects without knee injuries (CG) (mean age: 51.40±8.07) participated in this study. Participants were assessed in postural control through a force plate (Bertec Mod. USA), which provided information about the anterior-posterior (AP) and medial-lateral (ML) COP displacement during the mini-squat, in isometric, concentric and eccentric knee extensor torque (KET) (90°/s) through an isokinetic dynamometer (BiodexMulti-Joint System3, Biodex Medical Incorporation, New York, NY, USA), and in self-reported symptoms through the WOMAC questionnaire. The main outcomes measured were the AP and ML COP amplitude and velocity of displacement; isometric, concentric, and eccentric KET and self-reported physical function, stiffness and pain. No significant differences were found between groups for postural control (p>0.05). Significant lower eccentric KET (p=0.01) and higher scores for the WOMAC subscales of pain (p=postural instability and the need to include quadriceps muscle strengthening, especially by eccentric contractions. The relationship between the self-reported symptoms and a lower and slower COP displacement suggest that the postural control strategy during tasks with a semi-flexed knee

  5. Neural basis of postural focus effect on concurrent postural and motor tasks: phase-locked electroencephalogram responses.

    Science.gov (United States)

    Huang, Cheng-Ya; Zhao, Chen-Guang; Hwang, Ing-Shiou

    2014-11-01

    Dual-task performance is strongly affected by the direction of attentional focus. This study investigated neural control of a postural-suprapostural procedure when postural focus strategy varied. Twelve adults concurrently conducted force-matching and maintained stabilometer stance with visual feedback on ankle movement (visual internal focus, VIF) and on stabilometer movement (visual external focus, VEF). Force-matching error, dynamics of ankle and stabilometer movements, and event-related potentials (ERPs) were registered. Postural control with VEF caused superior force-matching performance, more complex ankle movement, and stronger kinematic coupling between the ankle and stabilometer movements than postural control with VIF. The postural focus strategy also altered ERP temporal-spatial patterns. Postural control with VEF resulted in later N1 with less negativity around the bilateral fronto-central and contralateral sensorimotor areas, earlier P2 deflection with more positivity around the bilateral fronto-central and ipsilateral temporal areas, and late movement-related potential commencing in the left frontal-central area, as compared with postural control with VIF. The time-frequency distribution of the ERP principal component revealed phase-locked neural oscillations in the delta (1-4Hz), theta (4-7Hz), and beta (13-35Hz) rhythms. The delta and theta rhythms were more pronounced prior to the timing of P2 positive deflection, and beta rebound was greater after the completion of force-matching in VEF condition than VIF condition. This study is the first to reveal the neural correlation of postural focusing effect on a postural-suprapostural task. Postural control with VEF takes advantage of efficient task-switching to facilitate autonomous postural response, in agreement with the "constrained-action" hypothesis. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Carpal instability

    International Nuclear Information System (INIS)

    Schmitt, R.; Froehner, S.; Coblenz, G.; Christopoulos, G.

    2006-01-01

    This review addresses the pathoanatomical basics as well as the clinical and radiological presentation of instability patterns of the wrist. Carpal instability mostly follows an injury; however, other diseases, like CPPD arthropathy, can be associated. Instability occurs either if the carpus is unable to sustain physiologic loads (''dyskinetics'') or suffers from abnormal motion of its bones during movement (''dyskinematics''). In the classification of carpal instability, dissociative subcategories (located within proximal carpal row) are differentiated from non-dissociative subcategories (present between the carpal rows) and combined patterns. It is essential to note that the unstable wrist initially does not cause relevant signs in standard radiograms, therefore being ''occult'' for the radiologic assessment. This paper emphasizes the high utility of kinematographic studies, contrast-enhanced magnetic resonance imaging (MRI) and MR arthrography for detecting these predynamic and dynamic instability stages. Later in the natural history of carpal instability, static malalignment of the wrist and osteoarthritis will develop, both being associated with significant morbidity and disability. To prevent individual and socio-economic implications, the handsurgeon or orthopedist, as well as the radiologist, is challenged for early and precise diagnosis. (orig.)

  7. Body posture modulates action perception.

    Science.gov (United States)

    Zimmermann, Marius; Toni, Ivan; de Lange, Floris P

    2013-04-03

    Recent studies have highlighted cognitive and neural similarities between planning and perceiving actions. Given that action planning involves a simulation of potential action plans that depends on the actor's body posture, we reasoned that perceiving actions may also be influenced by one's body posture. Here, we test whether and how this influence occurs by measuring behavioral and cerebral (fMRI) responses in human participants predicting goals of observed actions, while manipulating postural congruency between their own body posture and postures of the observed agents. Behaviorally, predicting action goals is facilitated when the body posture of the observer matches the posture achieved by the observed agent at the end of his action (action's goal posture). Cerebrally, this perceptual postural congruency effect modulates activity in a portion of the left intraparietal sulcus that has previously been shown to be involved in updating neural representations of one's own limb posture during action planning. This intraparietal area showed stronger responses when the goal posture of the observed action did not match the current body posture of the observer. These results add two novel elements to the notion that perceiving actions relies on the same predictive mechanism as planning actions. First, the predictions implemented by this mechanism are based on the current physical configuration of the body. Second, during both action planning and action observation, these predictions pertain to the goal state of the action.

  8. Postural stability in patients with decompression sickness evaluated by means of Quantitative Romberg testing

    DEFF Research Database (Denmark)

    Hedetoft, Morten; Hyldegaard, Ole

    2015-01-01

    obtained with the Quantitative Romberg test were observed in the group of DCS with vertigo relative to DCS without vertigo and healthy controls. A stepwise improvement in postural instability for DCS patients with vertigo was found following HBO2 therapy. After three treatments of HBO2, postural stability...... was found to be within the normal range of healthy controls. CONCLUSIONS: The Quantitative Romberg test offers the the clinician a fast, reliable and objective set of parametrical data to document postural instability in patients with either confirmed or suspected DCS.......OBJECTIVE: The present study was designed to retrospectively evaluate the use of quantitative Romberg's testing on postural stability during the course of hyperbaric oxygen (HBO2) therapy in patients presenting with decompression sickness (DCS). METHODS: The Quantitative Romberg test was used...

  9. Neck Vibration Proprioceptive Postural Response Intact in Progressive Supranuclear Palsy unlike Idiopathic Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Stefan Kammermeier

    2017-12-01

    Full Text Available Progressive supranuclear palsy (PSP and late-stage idiopathic Parkinson’s disease (IPD are neurodegenerative movement disorders resulting in different postural instability and falling symptoms. IPD falls occur usually forward in late stage, whereas PSP falls happen in early stages, mostly backward, unprovoked, and with high morbidity. Postural responses to sensory anteroposterior tilt illusion by bilateral dorsal neck vibration were probed in both groups versus healthy controls on a static recording posture platform. Three distinct anteroposterior body mass excursion peaks (P1–P3 were observed. 18 IPD subjects exhibited well-known excessive response amplitudes, whereas 21 PSP subjects’ responses remained unaltered to 22 control subjects. Neither IPD nor PSP showed response latency deficits, despite brainstem degeneration especially in PSP. The observed response patterns suggest that PSP brainstem pathology might spare the involved proprioceptive pathways and implies viability of neck vibration for possible biofeedback and augmentation therapy in PSP postural instability.

  10. Nuclear Posture Review

    Science.gov (United States)

    2018-02-01

    REVIEW margin for further delay in recapitalizing the physical infrastructure needed to produce strategic materials and components for U.S. nuclear... REVIEW 2018 This page left intentionally blank REVIEW NUCLEAR POSTURE REVIEW FEBRUARY 2018...OFFICE OF THE SECRETARY OF DEFENSE This page left intentionally blank REVIEW CONTENTS SECRETARY’S PREFACE

  11. 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

  12. Relationships among head posture, pain intensity, disability and deep cervical flexor muscle performance in subjects with postural neck pain

    Directory of Open Access Journals (Sweden)

    Arun V. Subbarayalu, PhD

    2017-12-01

    Full Text Available Objectives: Information Technology (IT professionals working with computers gradually develop forward head posture and, as a result, these professionals are susceptible to several neck disorders. This study intended to reveal the relationships between pain intensity, disability, head posture and deep cervical flexor (DCF muscle performance in patients with postural neck pain. Methods: A cross-sectional study was conducted on 84 IT professionals who were diagnosed with postural neck pain. The participants were recruited with a random sampling approach. A Visual Analogue Scale (VAS, the Northwick Park Neck Pain Questionnaire (NPQ, the Modified Head Posture Spinal Curvature Instrument (MHPSCI, and the Stabilizer Pressure Biofeedback Unit were used to measure neck pain intensity, neck disability, head posture, and DCF muscle performance, respectively. Results: The Pearson correlation coefficient revealed a significantly strong positive relationship between the VAS and the NPQ (r = 0.734. The cranio-vertebral (CV angle was found to have a significantly negative correlation with the VAS (r = −0.536 and a weak negative correlation with the NPQ (r = −0.389. Conclusion: This study concluded that a smaller CV angle corresponded to greater neck pain intensity and disability. Furthermore, there is no significant relationship between CV angle and DCF muscle performance, indicating that head posture re-education through postural correction exercises would not completely correct the motor control deficits in DCF muscles. In addition, a suitable exercise regimen that exclusively targets the deep cervical flexor muscle to improve its endurance is warranted. Keywords: Craniovertebral angle, Disability deep cervical flexors muscle performance, Head posture, Postural neck pain

  13. Forearm posture and mobility in quadrupedal dinosaurs.

    Science.gov (United States)

    VanBuren, Collin S; Bonnan, Matthew

    2013-01-01

    Quadrupedality evolved four independent times in dinosaurs; however, the constraints associated with these transitions in limb anatomy and function remain poorly understood, in particular the evolution of forearm posture and rotational ability (i.e., active pronation and supination). Results of previous qualitative studies are inconsistent, likely due to an inability to quantitatively assess the likelihood of their conclusions. We attempt to quantify antebrachial posture and mobility using the radius bone because its morphology is distinct between extant sprawled taxa with a limited active pronation ability and parasagittal taxa that have an enhanced ability to actively pronate the manus. We used a sliding semi-landmark, outline-based geometric morphometric approach of the proximal radial head and a measurement of the angle of curvature of the radius in a sample of 189 mammals, 49 dinosaurs, 35 squamates, 16 birds, and 5 crocodilians. Our results of radial head morphology showed that quadrupedal ceratopsians, bipedal non-hadrosaurid ornithopods, and theropods had limited pronation/supination ability, and sauropodomorphs have unique radial head morphology that likely allowed limited rotational ability. However, the curvature of the radius showed that no dinosaurian clade had the ability to cross the radius about the ulna, suggesting parallel antebrachial elements for all quadrupedal dinosaurs. We conclude that the bipedal origins of all quadrupedal dinosaur clades could have allowed for greater disparity in forelimb posture than previously appreciated, and future studies on dinosaur posture should not limit their classifications to the overly simplistic extant dichotomy.

  14. Forearm posture and mobility in quadrupedal dinosaurs.

    Directory of Open Access Journals (Sweden)

    Collin S VanBuren

    Full Text Available Quadrupedality evolved four independent times in dinosaurs; however, the constraints associated with these transitions in limb anatomy and function remain poorly understood, in particular the evolution of forearm posture and rotational ability (i.e., active pronation and supination. Results of previous qualitative studies are inconsistent, likely due to an inability to quantitatively assess the likelihood of their conclusions. We attempt to quantify antebrachial posture and mobility using the radius bone because its morphology is distinct between extant sprawled taxa with a limited active pronation ability and parasagittal taxa that have an enhanced ability to actively pronate the manus. We used a sliding semi-landmark, outline-based geometric morphometric approach of the proximal radial head and a measurement of the angle of curvature of the radius in a sample of 189 mammals, 49 dinosaurs, 35 squamates, 16 birds, and 5 crocodilians. Our results of radial head morphology showed that quadrupedal ceratopsians, bipedal non-hadrosaurid ornithopods, and theropods had limited pronation/supination ability, and sauropodomorphs have unique radial head morphology that likely allowed limited rotational ability. However, the curvature of the radius showed that no dinosaurian clade had the ability to cross the radius about the ulna, suggesting parallel antebrachial elements for all quadrupedal dinosaurs. We conclude that the bipedal origins of all quadrupedal dinosaur clades could have allowed for greater disparity in forelimb posture than previously appreciated, and future studies on dinosaur posture should not limit their classifications to the overly simplistic extant dichotomy.

  15. Gabapentin can improve postural stability and quality of life in primary orthostatic tremor.

    Science.gov (United States)

    Rodrigues, Julian P; Edwards, Dylan J; Walters, Susan E; Byrnes, Michelle L; Thickbroom, Gary; Stell, Rick; Mastaglia, Frank L

    2005-07-01

    Primary orthostatic tremor (OT) is characterized by leg tremor and instability on standing. High frequency (13-18 Hz) tremor bursting is present in leg muscles during stance, and posturography has shown greater than normal sway. We report on an open-label add-on study of gabapentin in 6 patients with OT. Six patients were studied with surface electromyography, force platform posturography, and a modified Parkinson's disease questionnaire (PDQ-39) quality of life (QOL) scale before and during treatment with gabapentin 300 mg t.d.s. If on other medications for OT, these were continued unchanged. Of the 6 patients, 4 reported a subjective benefit of 50 to 75% with gabapentin, 3 of whom showed reduced tremor amplitude and postural sway of up to 70%. Dynamic balance improved in all 3 patients who completed the protocol. QOL data from 5 patients showed improvement in all cases. No adverse effects were noted. Gabapentin may improve tremor, stability, and QOL in patients with OT, and symptomatic response correlated with a reduction in tremor amplitude and postural sway. The findings confirm previous reports of symptomatic benefit with gabapentin and provide justification for larger controlled clinical trials. Further work is required to establish the optimal dosage and to validate the methods used to quantify the response to treatment. Copyright 2005 Movement Disorder Society.

  16. Chronic Low Quality Sleep Impairs Postural Control in Healthy Adults.

    Science.gov (United States)

    Furtado, Fabianne; Gonçalves, Bruno da Silva B; Abranches, Isabela Lopes Laguardia; Abrantes, Ana Flávia; Forner-Cordero, Arturo

    2016-01-01

    The lack of sleep, both in quality and quantity, is an increasing problem in modern society, often related to workload and stress. A number of studies have addressed the effects of acute (total) sleep deprivation on postural control. However, up to date, the effects of chronic sleep deficits, either in quantity or quality, have not been analyzed. Thirty healthy adults participated in the study that consisted of registering activity with a wrist actigraph for more than a week before performing a series of postural control tests. Sleep and circadian rhythm variables were correlated and the sum of activity of the least active 5-h period, L5, a rhythm variable, obtained the greater coefficient value with sleep quality variables (wake after sleep onset WASO and efficiency sleep). Cluster analysis was performed to classify subjects into two groups based on L5 (low and high). The balance tests scores used to asses postural control were measured using Biodex Balance System and were compared between the two groups with different sleep quality. The postural tests were divided into dynamic (platform tilt with eyes open, closed and cursor) and static (clinical test of sensory integration). The results showed that during the tests with eyes closed, the group with worse sleep quality had also worse postural control performance. Lack of vision impairs postural balance more deeply in subjects with chronic sleep inefficiency. Chronic poor sleep quality impairs postural control similarly to total sleep deprivation.

  17. Chronic Low Quality Sleep Impairs Postural Control in Healthy Adults.

    Directory of Open Access Journals (Sweden)

    Fabianne Furtado

    Full Text Available The lack of sleep, both in quality and quantity, is an increasing problem in modern society, often related to workload and stress. A number of studies have addressed the effects of acute (total sleep deprivation on postural control. However, up to date, the effects of chronic sleep deficits, either in quantity or quality, have not been analyzed. Thirty healthy adults participated in the study that consisted of registering activity with a wrist actigraph for more than a week before performing a series of postural control tests. Sleep and circadian rhythm variables were correlated and the sum of activity of the least active 5-h period, L5, a rhythm variable, obtained the greater coefficient value with sleep quality variables (wake after sleep onset WASO and efficiency sleep. Cluster analysis was performed to classify subjects into two groups based on L5 (low and high. The balance tests scores used to asses postural control were measured using Biodex Balance System and were compared between the two groups with different sleep quality. The postural tests were divided into dynamic (platform tilt with eyes open, closed and cursor and static (clinical test of sensory integration. The results showed that during the tests with eyes closed, the group with worse sleep quality had also worse postural control performance. Lack of vision impairs postural balance more deeply in subjects with chronic sleep inefficiency. Chronic poor sleep quality impairs postural control similarly to total sleep deprivation.

  18. Postural Control and Gait Performance in the Diabetic Peripheral Neuropathy: A Systematic Review.

    Science.gov (United States)

    Mustapa, Amirah; Justine, Maria; Mohd Mustafah, Nadia; Jamil, Nursuriati; Manaf, Haidzir

    2016-01-01

    Purpose. The aim of this paper is to review the published studies on the characteristics of impairments in the postural control and gait performance in diabetic peripheral neuropathy (DPN). Methods. A review was performed by obtaining publication of all papers reporting on the postural control and gait performance in DPN from Google Scholar, Ovid, SAGE, Springerlink, Science Direct (SD), EBSCO Discovery Service, and Web of Science databases. The keywords used for searching were "postural control," "balance," "gait performance," "diabetes mellitus," and "diabetic peripheral neuropathy." Results. Total of 4,337 studies were hit in the search. 1,524 studies were screened on their titles and citations. Then, 79 studies were screened on their abstract. Only 38 studies were eligible to be selected: 17 studies on postural control and 21 studies on the gait performance. Most previous researches were found to have strong evidence of postural control impairments and noticeable gait deficits in DPN. Deterioration of somatosensory, visual, and vestibular systems with the pathologic condition of diabetes on cognitive impairment causes further instability of postural and gait performance in DPN. Conclusions. Postural instability and gait imbalance in DPN may contribute to high risk of fall incidence, especially in the geriatric population. Thus, further works are crucial to highlight this fact in the hospital based and community adults.

  19. Postural Control and Gait Performance in the Diabetic Peripheral Neuropathy: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Amirah Mustapa

    2016-01-01

    Full Text Available Purpose. The aim of this paper is to review the published studies on the characteristics of impairments in the postural control and gait performance in diabetic peripheral neuropathy (DPN. Methods. A review was performed by obtaining publication of all papers reporting on the postural control and gait performance in DPN from Google Scholar, Ovid, SAGE, Springerlink, Science Direct (SD, EBSCO Discovery Service, and Web of Science databases. The keywords used for searching were “postural control,” “balance,” “gait performance,” “diabetes mellitus,” and “diabetic peripheral neuropathy.” Results. Total of 4,337 studies were hit in the search. 1,524 studies were screened on their titles and citations. Then, 79 studies were screened on their abstract. Only 38 studies were eligible to be selected: 17 studies on postural control and 21 studies on the gait performance. Most previous researches were found to have strong evidence of postural control impairments and noticeable gait deficits in DPN. Deterioration of somatosensory, visual, and vestibular systems with the pathologic condition of diabetes on cognitive impairment causes further instability of postural and gait performance in DPN. Conclusions. Postural instability and gait imbalance in DPN may contribute to high risk of fall incidence, especially in the geriatric population. Thus, further works are crucial to highlight this fact in the hospital based and community adults.

  20. Postural control and freezing of gait in Parkinson's disease.

    Science.gov (United States)

    Schlenstedt, Christian; Muthuraman, Muthuraman; Witt, Karsten; Weisser, Burkhard; Fasano, Alfonso; Deuschl, Günther

    2016-03-01

    The relationship between freezing of gait (FOG) and postural instability in Parkinson's disease (PD) is unclear. We analyzed the impact of FOG on postural control. 31 PD patients with FOG (PD+FOG), 27 PD patients without FOG (PD-FOG) and 22 healthy control (HC) were assessed in the ON state. Postural control was measured with the Fullerton Advanced Balance (FAB) scale and with center of pressure (COP) analysis during quiet stance and maximal voluntary forward/backward leaning. The groups were balanced concerning age, disease duration and disease severity. PD+FOG performed significantly worse in the FAB scale (21.8 ± 5.8) compared to PD-FOG (25.6 ± 5.0) and HC (34.9 ± 2.4) (mean ± SD, p postural control asymmetry. PD+FOG have reduced postural control compared to PD-FOG and HC. Our results show a relationship between the anterior-posterior COP position during quiet stance and FOG. The COP shift towards posterior in PD+FOG leads to a restricted precondition to generate forward progression during gait initiation. This may contribute to the occurrence of FOG or might be a compensatory strategy to avoid forward falls. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. POSTURAL SHOCK IN PREGNANCY

    Science.gov (United States)

    Wilkening, Ralph L.; Knauer, John; Larson, Roger K.

    1955-01-01

    Signs and symptoms of shock may be produced in some patients in late pregnancy by putting them in the dorsal recumbent posture. Change from this position will relieve the condition. The features of the supine hypotensive syndrome can be duplicated by applying pressure to the abdomen with the patient in a lateral position. The postural variations of venous pressure, blood pressure, and pulse appear to be due to obstruction of venous return from the lower portion of the body caused by the large uterus of late pregnancy compressing the vena cava. When shock is observed in a woman in late pregnancy, she should be turned to a lateral position before more active measures of treatment are begun. ImagesFigure 1. PMID:14351983

  2. Relationship between static foot posture and foot mobility

    Directory of Open Access Journals (Sweden)

    McPoil Thomas G

    2011-01-01

    Full Text Available Abstract Background It is not uncommon for a person's foot posture and/or mobility to be assessed during a clinical examination. The exact relationship, however, between static posture and mobility is not known. Objective The purpose of this study was to determine the degree of association between static foot posture and mobility. Method The static foot posture and foot mobility of 203 healthy individuals was assessed and then analyzed to determine if low arched or "pronated" feet are more mobile than high arched or "supinated" feet. Results The study demonstrated that those individuals with a lower standing dorsal arch height and/or a wider standing midfoot width had greater mobility in their foot. In addition, those individuals with higher Foot Posture Index (FPI values demonstrated greater mobility and those with lower FPI values demonstrated less mobility. Finally, the amount of foot mobility that an individual has can be predicted reasonably well using either a 3 or 4 variable linear regression model. Conclusions Because of the relationship between static foot posture and mobility, it is recommended that both be assessed as part of a comprehensive evaluation of a individual with foot problems.

  3. 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.

  4. Increased alertness, better than posture prioritization, explains dual-task performance in prosthesis users and controls under increasing postural and cognitive challenge.

    Science.gov (United States)

    Howard, Charla L; Perry, Bonnie; Chow, John W; Wallace, Chris; Stokic, Dobrivoje S

    2017-11-01

    Sensorimotor impairments after limb amputation impose a threat to stability. Commonly described strategies for maintaining stability are the posture first strategy (prioritization of balance) and posture second strategy (prioritization of concurrent tasks). The existence of these strategies was examined in 13 below-knee prosthesis users and 15 controls during dual-task standing under increasing postural and cognitive challenge by evaluating path length, 95% sway area, and anterior-posterior and medial-lateral amplitudes of the center of pressure. The subjects stood on two force platforms under usual (hard surface/eyes open) and difficult (soft surface/eyes closed) conditions, first alone and while performing a cognitive task without and then with instruction on cognitive prioritization. During standing alone, sway was not significantly different between groups. After adding the cognitive task without prioritization instruction, prosthesis users increased sway more under the dual-task than single-task standing (p ≤ 0.028) during both usual and difficult conditions, favoring the posture second strategy. Controls, however, reduced dual-task sway under a greater postural challenge (p ≤ 0.017), suggesting the posture first strategy. With prioritization of the cognitive task, sway was unchanged or reduced in prosthesis users, suggesting departure from the posture second strategy, whereas controls maintained the posture first strategy. Individual analysis of dual tasking revealed that greater postural demand in controls and greater cognitive challenge in prosthesis users led to both reduced sway and improved cognitive performance, suggesting cognitive-motor facilitation. Thus, activation of additional resources through increased alertness, rather than posture prioritization, may explain dual-task performance in both prosthesis users and controls under increasing postural and cognitive challenge.

  5. 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.

  6. Postural orientation and equilibrium: what do we need to know about neural control of balance to prevent falls?

    Science.gov (United States)

    Horak, Fay B

    2006-09-01

    Postural control is no longer considered simply a summation of static reflexes but, rather, a complex skill based on the interaction of dynamic sensorimotor processes. The two main functional goals of postural behaviour are postural orientation and postural equilibrium. Postural orientation involves the active alignment of the trunk and head with respect to gravity, support surfaces, the visual surround and internal references. Sensory information from somatosensory, vestibular and visual systems is integrated, and the relative weights placed on each of these inputs are dependent on the goals of the movement task and the environmental context. Postural equilibrium involves the coordination of movement strategies to stabilise the centre of body mass during both self-initiated and externally triggered disturbances of stability. The specific response strategy selected depends not only on the characteristics of the external postural displacement but also on the individual's expectations, goals and prior experience. Anticipatory postural adjustments, prior to voluntary limb movement, serve to maintain postural stability by compensating for destabilising forces associated with moving a limb. The amount of cognitive processing required for postural control depends both on the complexity of the postural task and on the capability of the subject's postural control system. The control of posture involves many different underlying physiological systems that can be affected by pathology or sub-clinical constraints. Damage to any of the underlying systems will result in different, context-specific instabilities. The effective rehabilitation of balance to improve mobility and to prevent falls requires a better understanding of the multiple mechanisms underlying postural control.

  7. Validity and reliability of a dental operator posture assessment instrument (PAI).

    Science.gov (United States)

    Branson, Bonnie G; Williams, Karen B; Bray, Kimberly Krust; Mcllnay, Sandy L; Dickey, Diana

    2002-01-01

    Basic operating posture is considered an important occupational health issue for oral health care clinicians. It is generally agreed that the physical posture of the operator, while providing care, should be such that all muscles are in a relaxed, well-balanced, and neutral position. Postures outside of this neutral position are likely to cause musculoskeletal discomfort. To date, the range of the neutral operator position has not been well-defined; nor have any specific instruments been identified that can quantitatively or semi-quantitatively assess dental operator posture. This paper reports on the development of an instrument that can be used to semi-quantitatively evaluate postural components. During the first phase of the study, an expert panel defined the basic parameters for acceptable, compromised, and harmful operator postures and established face validity of a posture assessment instrument (PAI). During the second phase, the PAI was tested for reliability using generalizability theory. Four raters tested the instrument for reliability. Overall, total PAI scores were similar amongst three of the raters, with the fourth rater's scores being slightly greater than the other three. The main effect of the rater on individual postural components was moderate, indicating that rater variance contributed to 11.9% of total variance. The PAI measures posture as it occurs and will have numerous applications when evaluating operator performance in the dental and dental hygiene education setting. Also, the PAI will prove useful when examining the effects of operator posture and musculoskeletal disorders.

  8. Anticipatory and Compensatory Postural Adjustments in Response to External Lateral Shoulder Perturbations in Subjects with Parkinson's Disease.

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    Alexandre Kretzer E Castro de Azevedo

    Full Text Available The purpose of this study was to investigate the anticipatory (APA and compensatory (CPA postural adjustments in individuals with Parkinson's disease (PD during lateral instability of posture. Twenty-six subjects (13 individuals with PD and 13 healthy matched controls were exposed to predictable lateral postural perturbations. The electromyographic (EMG activity of the lateral muscles and the displacement of the center of pressure (COP were recorded during four time intervals that are typical for postural adjustments, i.e., immediately before (APA1, APA2 and after (CPA1 and CPA2 the postural disturbances. The magnitude of the activity of the lateral muscles in the group with PD was lower only during the CPA time intervals and not during the anticipatory adjustments (APAs. Despite this finding, subjects with PD exhibit smaller COP excursions before and after the disturbance, probably due to lack of flexibility and proprioceptive impairments. The results of this study suggest that postural instability in subjects with PD can be partially explained by decreased postural sway, before and after perturbations, and reduced muscular activity after body disturbances. Our findings can motivate new studies to investigate therapeutic interventions that optimize the use of postural adjustment strategies in subjects with PD.

  9. The differences in postural reactions between scoliosis and scoliotic posture

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    Jacek Wilczyński

    2017-05-01

    Full Text Available The aim of the research was to demonstrate the differences in amplitudes of postural reactions in girls with scoliotic posture and idiopathic scoliosis. 28 girls aged 7-18 years old were involved in the study. Children attended to the Interschool Centre of Corrective Exercises in Starachowice. The research was conducted in June 2011. Spine research was made by Exhibeon digital radiography. Based on the size of the angle of spinal curvature there were identified: scoliotic posture: 1-9° and scoliosis: ≥10°. Postural reactions were examined by static-dynamic Tecnobody’s ST 310 Plus Stability System platform. There were 21 (75% children with scoliotic posture, and 7 (25% with idiopathic scoliosis. Student's t-test showed a significantly higher postural reactions for scoliosis in relation to scoliotic postures in case of: Average Forward-Backward Speed (OE, (p=0,05, Medium-Lateral Standard Deviation X (CE, (p=0,002, and Ellipse area (CE, (p=0,012. To verify the significant differences, demonstrating the lack of homogeneity of variance, the Mann–Whitney U-test has been used, which showed a significant differences between the scoliotic posture and scoliosis in case of: Medium-Lateral Standard Deviation X (CE, (p=0,0012, Average Forward-Backward Speed (OE, (p=0,0548, and Ellipse area (CE (p=0,0047. Together with an increase of the angle of curvature, the value of these postural reactions also grew. Most of postural reactions didn’t fit the norm.

  10. Do older adults perceive postural constraints for reach estimation?

    Science.gov (United States)

    Cordova, Alberto; Gabbard, Carl

    2014-01-01

    BACKGROUND/STUDY CONTEXT: Recent evidence indicates that older persons have difficulty mentally representing intended movements. Furthermore, in an estimation of reach paradigm using motor imagery, a form of mental representation, older persons significantly overestimated their ability compared with young adults. The authors tested the notion that older adults may also have difficulty perceiving the postural constraints associated with reach estimation. The authors compared young (Mage = 22 years) and older (Mage = 67) adults on reach estimation while seated and in a more postural demanding standing and leaning forward position. The expectation was a significant postural effect with the standing condition, as evidenced by reduced overestimation. Whereas there was no difference between groups in the seated condition (both overestimated), older adults underestimated whereas the younger group once again overestimated in the standing condition. From one perspective, these results show that older adults do perceive postural constraints in light of their own physical capabilities. That is, that group perceived greater postural demands with the standing posture and elected to program a more conservative strategy, resulting in underestimation.

  11. Quantitative Postural Analysis of Children With Congenital Visual Impairment.

    Science.gov (United States)

    de Pádua, Michelle; Sauer, Juliana F; João, Silvia M A

    2018-01-01

    The aim of this study was to compare the postural alignment of children with visual impairment with that of children without visual impairment. The sample studied was 74 children of both sexes ages 5 to 12 years. Of these, 34 had visual impairment and 40 were control children. Digital photos from the standing position were used to analyze posture. Postural variables, such as tilt of the head, shoulder position, scapula position, lateral deviation of the spine, ankle position in the frontal plane and head posture, angle of thoracic kyphosis, angle of lumbar lordosis, pelvis position, and knee position in the frontal and sagittal planes, were measured with the Postural Assessment Software 0.63, version 36 (SAPO, São Paulo, Brazil), with markers placed in predetermined bony landmarks. The main results of this study showed that children with visual impairment have increased head tilt (P Visual impairment influences postural alignment. Children with visual impairment had increased head tilt, uneven shoulders, greater lateral deviation of the spine, thoracic kyphosis, lower lumbar lordosis, and more severe valgus deformities on knees. Copyright © 2017. Published by Elsevier Inc.

  12. Increased dynamic regulation of postural tone through Alexander Technique training.

    Science.gov (United States)

    Cacciatore, T W; Gurfinkel, V S; Horak, F B; Cordo, P J; Ames, K E

    2011-02-01

    Gurfinkel and colleagues (2006) recently found that healthy adults dynamically modulate postural muscle tone in the body axis during anti-gravity postural maintenance and that this modulation is inversely correlated with axial stiffness. Our objective in the present study was to investigate whether dynamic modulation of axial postural tone can change through training. We examined whether teachers of the Alexander Technique (AT), who undergo "long-term" (3-year) training, have greater modulation of axial postural tone than matched control subjects. In addition, we performed a longitudinal study on the effect of "short-term" (10-week) AT training on the axial postural tone of individuals with low back pain (LBP), since short term AT training has previously been shown to reduce LBP. Axial postural tone was quantified by measuring the resistance of the neck, trunk and hips to small (±10°), slow (1°/s) torsional rotation during stance. Modulation of tone was determined by the torsional resistance to rotation (peak-to-peak, phase-advance, and variability of torque) and axial muscle activity (EMG). Peak-to-peak torque was lower (∼50%), while phase-advance and cycle-to-cycle variability were enhanced for AT teachers compared to matched control subjects at all levels of the axis. In addition, LBP subjects decreased trunk and hip stiffness following short-term AT training compared to a control intervention. While changes in static levels of postural tone may have contributed to the reduced stiffness observed with the AT, our results suggest that dynamic modulation of postural tone can be enhanced through long-term training in the AT, which may constitute an important direction for therapeutic intervention. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. POSTUR PADA WANITA HAMIL

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    Paryono .

    2013-09-01

    Full Text Available ABSTRACTIntroduction: Pregnancy effects in changes on all body systems leading to a new balance women and maternal adaptation.Weight gain in pregnant women from both the uterus and breast development generally occurs at the front of the body, butwhen standing they were still able to maintain a posture that does not face. The purpose of this article is to examine thereasons why pregnant women do not fall to front and how the good attitude of the pregnant woman's body.Materials and Methods: Material of this article are literatures related to pregnancy and the pregnant woman's bodyp o s t u r e , a n d t h e y w e r e c o l l e c t e d b y l i t e r a t u r e ' s s t u d y a n d l i t e r a r y s t u d y .Discussion: Increased abdominal distension that makes tilting the pelvis forward, decreased abdominal muscle tone andincrease weight gain in late pregnancy requires a readjustment spinal curvature. Woman's center of gravity shifts forward.Lumbosakrum normal curve should be more curved and the curvature of the servikodorsal be formed to maintain balance.Assessment of anterior view, lateral and posterior body should include an understanding of the physical structures such asjoints and muscles as well as how the meridian pathways. To compensate for the anterior position of the enlarged uterus,lordosis shifting center of gravity to the back of the lower limbs. There is an increased sacroiliac joint mobility,sakrokoksigeal, and pubic joints during pregnancy, possibly due to hormonal changes. Individual assessments will berequired to determine the pattern of muscle for every person, especially for those who have musculoskeletal problems.Conclusions and Recommendations: The size of the stomach in a pregnant woman, then the gravity of the body changes.Body to be biased toward the rear, but this position makes your back hurt. Advice for pregnant women in order to maintainyour posture as follows: head upKeyword : Posture, Pregnancy, Women.

  14. Direct observation of nonequilibrium electroosmotic instability

    NARCIS (Netherlands)

    Rubinstein, S.M.; Manukyan, G.; Staicu, A.D.; Rubinstein, I.; Zaltzman, B.; Lammertink, Rob G.H.; Mugele, Friedrich Gunther; Wessling, Matthias

    2008-01-01

    We present a visualization of the predicted instability in ionic conduction from a binary electrolyte into a charge selective solid. This instability develops when a voltage greater than critical is applied to a thin layer of copper sulfate flanked by a copper anode and a cation selective membrane.

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

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    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

  16. Body posture and postural stability of people practicing qigong

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    Jacek Wilczyński

    2015-07-01

    Full Text Available Introduction: Correct and stable posture is essential for the implementation of the majority of voluntary movements and locomotion. The study of postural stability is an element of clinical trials evaluating physical activity in order to determine the optimal therapeutic procedures. Qigong exercises are not only a form of prevention, helpful in maintaining wellbeing, but also a means of therapy in many diseases, including disorders of postural stability. Aim of the research: To analyse the association between the quality of posture and postural stability of people practicing qigong. Material and methods : The study involved 32 people. The mean age of those tested was 54 years. Posture study used optoelectronic method Diers formetric III 4D. Postural stability was tested on the platform Biodex Balance System. The studies were performed at the Posture Laboratory of the Institute of Physiotherapy at Jan Kochanowski University in Kielce. Results and conclusions : Spearman rank order correlation showed a positive correlation of relative rotation of the spine area with a general indicator of stability (p = 0.0206 at an average level (R = 0.4075 and with the index of the stability A/P (p = 0.0310, although at a lower level (R = 0.3819. With the increase in the relative rotation of the spine area the overall stability indicator and stability indicator A/P also increased. Significant positive correlations were also seen for the surface rotation (+max and a general indication of the stability and the stability index A/P. With the increase of surface rotation (+max of the spine the overall stability indicator and stability indicator A/P also increased.

  17. First-Person Perspective Virtual Body Posture Influences Stress: A Virtual Reality Body Ownership Study

    Science.gov (United States)

    Bergström, Ilias; Kilteni, Konstantina; Slater, Mel

    2016-01-01

    In immersive virtual reality (IVR) it is possible to replace a person’s real body by a life-sized virtual body that is seen from first person perspective to visually substitute their own. Multisensory feedback from the virtual to the real body (such as the correspondence of touch and also movement) can also be present. Under these conditions participants typically experience a subjective body ownership illusion (BOI) over the virtual body, even though they know that it is not their real one. In most studies and applications the posture of the real and virtual bodies are as similar as possible. Here we were interested in whether the BOI is diminished when there are gross discrepancies between the real and virtual body postures. We also explored whether a comfortable or uncomfortable virtual body posture would induce feelings and physiological responses commensurate with the posture. We carried out an experiment with 31 participants in IVR realized with a wide field-of-view head-mounted display. All participants were comfortably seated. Sixteen of them were embodied in a virtual body designed to be in a comfortable posture, and the remainder in an uncomfortable posture. The results suggest that the uncomfortable body posture led to lesser subjective BOI than the comfortable one, but that participants in the uncomfortable posture experienced greater awareness of their autonomic physiological responses. Moreover their heart rate, heart rate variability, and the number of mistakes in a cognitive task were associated with the strength of their BOI in the uncomfortable posture: greater heart rate, lower heart rate variability and more mistakes were associated with higher levels of the BOI. These findings point in a consistent direction—that the BOI over a body that is in an uncomfortable posture can lead to subjective, physiological and cognitive effects consistent with discomfort that do not occur with the BOI over a body in a comfortable posture. PMID:26828365

  18. Mild hallux valgus angle affects single-limb postural stability in asymptomatic subjects.

    Science.gov (United States)

    Çınar-Medeni, Özge; Atalay Guzel, Nevin; Basar, Selda

    2016-01-01

    Single-limb postural stability is a key component of lower extremity functional status. Factors affecting postural stability should be well defined to prevent injuries. The aim of this study was to investigate the effect of the hallux valgus angle on postural stability in asymptomatic subjects. A total of 19 subjects were included in the study. The hallux valgus angle and postural stability were assessed. Participants were assigned to two groups according to whether the hallux valgus angle was pathological or not. A hallux valgus angle greater than 15 degrees was accepted as pathological. The relationship between the hallux valgus angle and postural stability, and the differences in postural stability scores between the two groups were analyzed. Postural stability was assessed with a stabilometer. The test was performed with the eyes open. We found a significant correlation between the hallux valgus angle and mediolateral and overall stability index (r= 0.484, p= 0.036; r = 0.463, p= 0.046 respectively). Subjects with a pathological mild hallux valgus angle had greater stability index scores than normal subjects (phallux valgus angle has negative effects on postural stability as a forefoot deformity. This deformity should be taken into account for injury prevention strategies in pain-free younger adults.

  19. Does a crouched leg posture enhance running stability and robustness?

    Science.gov (United States)

    Blum, Yvonne; Birn-Jeffery, Aleksandra; Daley, Monica A; Seyfarth, Andre

    2011-07-21

    Humans and birds both walk and run bipedally on compliant legs. However, differences in leg architecture may result in species-specific leg control strategies as indicated by the observed gait patterns. In this work, control strategies for stable running are derived based on a conceptual model and compared with experimental data on running humans and pheasants (Phasianus colchicus). From a model perspective, running with compliant legs can be represented by the planar spring mass model and stabilized by applying swing leg control. Here, linear adaptations of the three leg parameters, leg angle, leg length and leg stiffness during late swing phase are assumed. Experimentally observed kinematic control parameters (leg rotation and leg length change) of human and avian running are compared, and interpreted within the context of this model, with specific focus on stability and robustness characteristics. The results suggest differences in stability characteristics and applied control strategies of human and avian running, which may relate to differences in leg posture (straight leg posture in humans, and crouched leg posture in birds). It has been suggested that crouched leg postures may improve stability. However, as the system of control strategies is overdetermined, our model findings suggest that a crouched leg posture does not necessarily enhance running stability. The model also predicts different leg stiffness adaptation rates for human and avian running, and suggests that a crouched avian leg posture, which is capable of both leg shortening and lengthening, allows for stable running without adjusting leg stiffness. In contrast, in straight-legged human running, the preparation of the ground contact seems to be more critical, requiring leg stiffness adjustment to remain stable. Finally, analysis of a simple robustness measure, the normalized maximum drop, suggests that the crouched leg posture may provide greater robustness to changes in terrain height

  20. Instability following total knee arthroplasty.

    Science.gov (United States)

    Rodriguez-Merchan, E Carlos

    2011-10-01

    Background Knee prosthesis instability (KPI) is a frequent cause of failure of total knee arthroplasty. Moreover, the degree of constraint required to achieve immediate and long-term stability in total knee arthroplasty (TKA) is frequently debated. Questions This review aims to define the problem, analyze risk factors, and review strategies for prevention and treatment of KPI. Methods A PubMed (MEDLINE) search of the years 2000 to 2010 was performed using two key words: TKA and instability. One hundred and sixty-five initial articles were identified. The most important (17) articles as judged by the author were selected for this review. The main criteria for selection were that the articles addressed and provided solutions to the diagnosis and treatment of KPI. Results Patient-related risk factors predisposing to post-operative instability include deformity requiring a large surgical correction and aggressive ligament release, general or regional neuromuscular pathology, and hip or foot deformities. KPI can be prevented in most cases with appropriate selection of implants and good surgical technique. When ligament instability is anticipated post-operatively, the need for implants with a greater degree of constraint should be anticipated. In patients without significant varus or valgus malalignment and without significant flexion contracture, the posterior cruciate ligament (PCL) can be retained. However, the PCL should be sacrificed when deformity exists particularly in patients with rheumatoid arthritis, previous patellectomy, previous high tibial osteotomy or distal femoral osteotomy, and posttraumatic osteoarthritis with disruption of the PCL. In most cases, KPI requires revision surgery. Successful outcomes can only be obtained if the cause of KPI is identified and addressed. Conclusions Instability following TKA is a common cause of the need for revision. Typically, knees with deformity, rheumatoid arthritis, previous patellectomy or high tibial osteotomy, and

  1. Effects of focal ankle joint cooling on unipedal static balance in individuals with and without chronic ankle instability.

    Science.gov (United States)

    Kim, Kyung-Min; Hart, Joseph M; Saliba, Susan A; Hertel, Jay

    2015-01-01

    Application of cryotherapy over an injured joint has been shown to improve muscle function, yet it is unknown how ankle cryotherapy affects postural control. Our purpose was to determine the effects of a 20-min focal ankle joint cooling on unipedal static stance in individuals with and without chronic ankle instability (CAI). Fifteen young subjects with CAI (9 males, 6 females) and 15 healthy gender-matched controls participated. All subjects underwent two intervention sessions on different days in which they had a 1.5L plastic bag filled with either crushed ice (active treatment) or candy corn (sham) applied to the ankle. Unipedal stance with eyes closed for 10s were assessed with a forceplate before and after each intervention. Center of pressure (COP) data were used to compute 10 specific dependent measures including velocity, area, standard deviation (SD), and percent range of COP excursions, and mean and SD of time-to-boundary (TTB) minima in the anterior-posterior (AP) and mediolateral directions. For each measure a three-way (Group-Intervention-Time) repeated ANOVAs found no significant interactions and main effects involving intervention (all Ps > 0.05). There were group main effects found for mean velocity (F(1,28) = 6.46, P = .017), area (F(1,28) = 12.83, P = .001), and mean of TTB minima in the AP direction (F(1,28) = 5.19, P = .031) indicating that the CAI group demonstrated greater postural instability compared to the healthy group. Postural control of unipedal stance was not significantly altered following focal ankle joint cooling in groups both with and without CAI. Ankle joint cryotherapy was neither beneficial nor harmful to single leg balance. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Imaging Posture Veils Neural Signals

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    Robert T Thibault

    2016-10-01

    Full Text Available Whereas modern brain imaging often demands holding body positions incongruent with everyday life, posture governs both neural activity and cognitive performance. Humans commonly perform while upright; yet, many neuroimaging methodologies require participants to remain motionless and adhere to non-ecological comportments within a confined space. This inconsistency between ecological postures and imaging constraints undermines the transferability and generalizability of many a neuroimaging assay.Here we highlight the influence of posture on brain function and behavior. Specifically, we challenge the tacit assumption that brain processes and cognitive performance are comparable across a spectrum of positions. We provide an integrative synthesis regarding the increasingly prominent influence of imaging postures on autonomic function, mental capacity, sensory thresholds, and neural activity. Arguing that neuroimagers and cognitive scientists could benefit from considering the influence posture wields on both general functioning and brain activity, we examine existing imaging technologies and the potential of portable and versatile imaging devices (e.g., functional near infrared spectroscopy. Finally, we discuss ways that accounting for posture may help unveil the complex brain processes of everyday cognition.

  3. SHOULDER EXTERNAL ROTATOR STRENGTH IN RESPONSE TO VARIOUS SITTING POSTURES: A CONTROLLED LABORATORY STUDY.

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    Pheasant, Steven; Haydt, Richard; Gottstein, Thomas; Grasso, Anthony; Lombard, Nicholas; Stone, Brandon

    2018-02-01

    The forward head rounded shoulder (FHRS) sitting posture has been associated with decreased shoulder complex muscle strength and function. Upon clinical observation, the adverse effects of the FHRS sitting posture on shoulder complex isometric muscle strength is also present when testing controls for scapular position. The purpose of the study was to assess the effect of various sitting postures on shoulder external rotator muscle isometric strength when the strength testing controls for scapular position. A cohort study, with subjects serving as their own controls. One hundred subjects ages 20-26 participated in the study. Each subject was placed in a neutral cervical sitting (NCS) posture which was maintained for five minutes after which the strength of the dominant shoulder external rotators was immediately tested with the glenohumeral joint in the neutral position using a Micro-FET3 Hand Held Muscle Testing Dynamometer (HHMTD). Each subject was returned to the NCS posture for subsequent external rotator strength testing after five minutes in a FHRS sitting posture, five additional minutes in the NCS posture and five minutes in a retracted cervical sitting (RCS) posture resulting in each subjects' external rotator strength being tested on four occasions. Subjects were randomized for order between the FHRS and RCS postures. Mean strength values for each condition were normalized to the mean strength value for the 1 st NCS condition for each subject. A statistically significant decline in shoulder external rotator strength following the FHRS sitting posture occurred compared to the appropriate postural conditions (pexternal rotator strength following five minutes in the FHRS sitting posture. The average percentage of strength decline in those with greater than a 10% reduction in external rotator strength was 19%. Sixty-four percent of the subjects experienced less than a 10% decline in shoulder external rotator strength in response to the FHRS sitting posture

  4. Postural control assessment in students with normal hearing and sensorineural hearing loss.

    Science.gov (United States)

    Melo, Renato de Souza; Lemos, Andrea; Macky, Carla Fabiana da Silva Toscano; Raposo, Maria Cristina Falcão; Ferraz, Karla Mônica

    2015-01-01

    Children with sensorineural hearing loss can present with instabilities in postural control, possibly as a consequence of hypoactivity of their vestibular system due to internal ear injury. To assess postural control stability in students with normal hearing (i.e., listeners) and with sensorineural hearing loss, and to compare data between groups, considering gender and age. This cross-sectional study evaluated the postural control of 96 students, 48 listeners and 48 with sensorineural hearing loss, aged between 7 and 18 years, of both genders, through the Balance Error Scoring Systems scale. This tool assesses postural control in two sensory conditions: stable surface and unstable surface. For statistical data analysis between groups, the Wilcoxon test for paired samples was used. Students with hearing loss showed more instability in postural control than those with normal hearing, with significant differences between groups (stable surface, unstable surface) (ppostural control compared to normal hearing students of the same gender and age. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  5. Effect of Symmetry Improvement in Weight Bearing on Postural Stability of Hemiparetic Patients

    Directory of Open Access Journals (Sweden)

    Hossein Asghar-Hosseini

    2008-07-01

    Full Text Available Objective: Impaired postural control has been known as the main cause of fall in hemiparesis after stroke. Is Asymmetry of weight bearing on lower limb is one of the prominent characteristics of postural imbalance in these patients. The aim of this study was to evaluate the effect of symmetry improvement in weight bearing through therapeutic interventions on postural stability in hemiparetic patients. Materials & Methods: In this quasi – experimental study which 27 hemiparetic patients were selected through sample of convenience by simple method from men and women who were referred to neurology clinic of Hazrat-e-Rasool hospital. For postural assessment patients stood quietly with open eyes and close eyes on force plates. Primary assessments included evaluation of asymmetry index (AI, RMS COP displacement (Root Mean Square of Center of Pressure and RMS COP velocity in both frontal and sagital planes. Then a 10mm lift was inserted under the unaffected limb and primary assessments were repeated. Data were analyzed by repeated measure ANOVA test. Results: Simple main effect of lift on asymmetry index was significant (P<0/0001. There was no significant interaction between vision and lift. Simple main effect of lift on postural stability variables was also non significant (for RMS COP displacement in frontal and sagital planes P=0.186 and P=0.245, respectively and for RMS COP velocity P=0.259 and P=0.342 respectively. Conclusion: Inserting a lift can improve symmetry by shifting center of gravity to midline. Since symmetry improvement did not decrease postural instability, asymmetric weight bearing can not be the primary cause of postural instability and may not be the principal target of rehabilitation programs aiming at restoring standing balance after stroke.

  6. Cardiovascular function in pregnancy: effects of posture.

    Science.gov (United States)

    Del Bene, R; Barletta, G; Mello, G; Lazzeri, C; Mecacci, F; Parretti, E; Martini, E; Vecchiarino, S; Franchi, F; La Villa, G

    2001-04-01

    To evaluate the cardiovascular response to active postural changes in pregnancy. Prospective study. Outpatient Clinic, Fetal Maternity Unit. Sixteen healthy women referred prior to pregnancy. Heart rate, arterial pressure, echocardiographic end-diastolic and end-systolic left ventricular volumes (Teichholz' s formula) were measured in the three months before pregnancy, at the end of the first and second trimester, at mid third trimester, and six months after delivery in the supine and standing position, in thirteen women (mean age 33, range 25-38 years). Cardiac output (supine position) significantly increased (28%): it reached its maximum at the second trimester, remained steadily elevated in the mid third trimester, and returned to baseline after delivery. Cardiac output increased during pregnancy also in the active orthostatic position, the percentage increase being greater (70%) since the standing pre-conception value was lower. The postural stress induced similar changes in heart rate, arterial pressure and left ventricular ejection fraction before, during and after pregnancy. However, the reduction in cardiac output associated with early standing attenuated significantly at the second trimester and it was absent at mid third trimester (F = 3.13, P = 0.021). This was due to the interplay between the significantly lesser increase in systemic vascular resistance, occurring since the first trimester, and the significantly lesser decrease in left ventricular end-diastolic volume which was observed in the mid third trimester. These data indicate that the elevated cardiac output is adequately maintained in pregnancy during the postural challenge, due to optimisation of the responses of preload and afterload.

  7. Relationships between Task-Oriented Postural Control and Motor Ability in Children and Adolescents with Down Syndrome

    Science.gov (United States)

    Wang, Hui-Yi; Long, I-Man; Liu, Mei-Fang

    2012-01-01

    Individuals with Down syndrome (DS) have been characterized by greater postural sway in quiet stance and insufficient motor ability. However, there is a lack of studies to explore the properties of dynamic postural sway, especially under conditions of task-oriented movement. The purpose of this study was to investigate the relationships between…

  8. Investigating the Effects of Different Working Postures on Cognitive Performance

    Directory of Open Access Journals (Sweden)

    Sharareh Mohammadi

    2018-01-01

    Conclusion This study demonstrates that cognitive performance is affected by working postures. This study demonstrates that standard sitting posture is the best posture. Therefore, it is recommended that sitting posture can help in increasing cognitive performance in the workplace.

  9. Breathing pattern and head posture: changes in craniocervical angles.

    Science.gov (United States)

    Sabatucci, A; Raffaeli, F; Mastrovincenzo, M; Luchetta, A; Giannone, A; Ciavarella, D

    2015-04-01

    The aim of this study was to observe the influence of oral breathing on head posture and to establish possible postural changes observing the variation of craniocervical angles NSL/OPT and NSL/CVT between oral breathing subjects and physiological breathing subjects. A cross-sectional study was conducted. The sample included 115 subject, 56 boys and 59 girls, 5-22-year-old. Among these, 80 were classified as oral breathers and 35 as physiological breathers. The diagnosis of oral breathing was carried out thanks to characteristic signs and symptoms evaluated on clinical examination, the analysis of characteristic X-ray images, ENT examination with active anterior rhinomanometric (AAR) test. The structural and postural analysis was carried out, calculating the craniofacial angles NSL/OPT and NSL/CVT. Both NSL/OPT and NSL/CVT appear to be significantly greater to those observed in physiological breathing patients. This means that patients who tend to breathe through the mouth rather than exclusively through the nose show a reduction of cervical lordosis and a proinclination of the head. Our study confirms that the oral breathing modifies head position. The significant increase of the craniocervical angles NSL/OPT and NSL/CVT in patients with this altered breathing pattern suggests an elevation of the head and a greater extension of the head compared with the cervical spine. So, to correct the breathing pattern early, either during childhood or during adolescence, can lead to a progressive normalization of craniofacial morphology and head posture.

  10. STATIC AND DYNAMIC POSTURE CONTROL IN POSTLINGUAL COCHLEAR IMPLANTED PATIENTS: Effects of dual-tasking, visual and auditory inputs suppression

    Directory of Open Access Journals (Sweden)

    BERNARD DEMANZE eLaurence

    2014-01-01

    Full Text Available Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body’s position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of post-lingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static and dynamic conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO and eyes closed (EC conditions, with the cochlear implant activated (ON or not (OFF. Results showed that the CI patients significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk while the controls showed a whole body rigidification strategy. Hearing (prosthesis on as well as dual-tasking did not really improve the dynamic postural performance of the CI patients. We conclude that CI patients become strongly visual dependent mainly in challenging postural conditions.

  11. Do children perceive postural constraints when estimating reach or action planning?

    Science.gov (United States)

    Gabbard, Carl; Cordova, Alberto; Lee, Sunghan

    2009-03-01

    Estimation of whether an object is reachable from a specific body position constitutes an important aspect in effective motor planning. Researchers who estimate reachability by way of motor imagery with adults consistently report the tendency to overestimate, with some evidence of a postural effect (postural stability hypothesis). This idea suggests that perceived reaching limits depend on an individual's perceived postural constraints. Based on previous work with adults, the authors expected a significant postural effect with the Reach 2 condition, as evidenced by reduced overestimation. Furthermore, the authors hypothesized that the postural effect would be greater in younger children. They then tested these propositions among children aged 7, 9, and 11 years by asking them to estimate reach while seated (Reach 1) and in the more demanding posture of standing on 1 foot and leaning forward (Reach 2). Results indicated no age or condition difference, therefore providing no support for a postural effect. When the authors compared these data to a published report of adults, a developmental difference emerged. That is, adults recognize the perceived postural constraint of the standing position resulting in under- rather than overestimation, as displayed in the seated condition. Although preliminary, these observations suggest that estimates of reach (action planning) continue to be refined between late childhood and young adulthood.

  12. Kinetic theory of tearing instabilities

    International Nuclear Information System (INIS)

    Drake, J.F.; Lee, Y.C.

    1977-01-01

    The transition of the tearing instability from the collisional to the collisionless regime is investigated kinetically using a Fokker--Planck collision operator to represent electron-ion collisions. As a function of the collisionality of the plasma, the tearing instability falls into three regions, which are referred to as collisionless, semi-collisional, and collisional. The width Δ of the singular layer around kxB 0 =0 is limited by electron thermal motion along B 0 in the collisional and semi-collisional regimes and is typically smaller than rho/sub i/, the ion Larmor radius. Previously accepted theories, which are based on the assumption Δvery-much-greater-thanrho/sub i/, are found to be valid only in the collisional regime. The effects of density and temperature gradients on the instabilities are also studied. The tearing instability is only driven by the temperature gradient in the collisional and semi-collisional regimes. Numerical calculations indicate that the semi-collisional tearing instability is particularly relevant to present day high temperature tokamak discharges

  13. 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.

  14. Dual-Task Interference: The Effects of Verbal Cognitive Tasks on Upright Postural Stability in Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    J. D. Holmes

    2010-01-01

    Full Text Available Although dual-task interference has previously been demonstrated to have a significant effect on postural control among individuals with Parkinson's disease, the impact of speech complexity on postural control has not been demonstrated using quantitative biomechanical measures. The postural stability of twelve participants with idiopathic Parkinson's disease and twelve healthy age-matched controls was evaluated under three conditions: (1 without a secondary task, (2 performing a rote repetition task and (3 generating a monologue. Results suggested a significant effect of cognitive load on biomechanical parameters of postural stability. Although both groups increased their postural excursion, individuals with Parkinson's disease demonstrated significantly reduced excursion as compared with that of healthy age-matched controls. This suggests that participants with Parkinson's disease may be overconstraining their postural adjustments in order to focus attention on the cognitive tasks without losing their balance. Ironically, this overconstraint may place the participant at greater risk for a fall.

  15. Individual differences in brainstem and basal ganglia structure predict postural control and balance loss in young and older adults.

    Science.gov (United States)

    Boisgontier, Matthieu P; Cheval, Boris; Chalavi, Sima; van Ruitenbeek, Peter; Leunissen, Inge; Levin, Oron; Nieuwboer, Alice; Swinnen, Stephan P

    2017-02-01

    It remains unclear which specific brain regions are the most critical for human postural control and balance, and whether they mediate the effect of age. Here, associations between postural performance and corticosubcortical brain regions were examined in young and older adults using multiple structural imaging and linear mixed models. Results showed that of the regions involved in posture, the brainstem was the strongest predictor of postural control and balance: lower brainstem volume predicted larger center of pressure deviation and higher odds of balance loss. Analyses of white and gray matter in the brainstem showed that the pedunculopontine nucleus area appeared to be critical for postural control in both young and older adults. In addition, the brainstem mediated the effect of age on postural control, underscoring the brainstem's fundamental role in aging. Conversely, lower basal ganglia volume predicted better postural performance, suggesting an association between greater neural resources in the basal ganglia and greater movement vigor, resulting in exaggerated postural adjustments. Finally, results showed that practice, shorter height and heavier weight (i.e., higher body mass index), higher total physical activity, and larger ankle active (but not passive) range of motion were predictive of more stable posture, irrespective of age. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Thermoregulatory postures limit antipredator responses in peafowl.

    Science.gov (United States)

    Yorzinski, Jessica L; Lam, Jennifer; Schultz, Rachel; Davis, Melissa

    2018-01-05

    Many animals inhabit environments where they experience temperature fluctuations. One way in which animals can adjust to these temperature changes is through behavioral thermoregulation. However, we know little about the thermal benefits of postural changes and the costs they may incur. In this study, we examined the thermoregulatory role of two postures, the head-tuck and leg-tuck posture, in peafowl ( Pavo cristatus ) and evaluated whether the head-tuck posture imposes a predation cost. The heads and legs of peafowl are significantly warmer when the birds exhibit these postures, demonstrating that these postures serve an important thermoregulatory role. In addition, the birds are slower to respond to an approaching threat when they display the head-tuck posture, suggesting that a thermoregulatory posture can limit antipredator behavior. © 2018. Published by The Company of Biologists Ltd.

  17. Thermoregulatory postures limit antipredator responses in peafowl

    Directory of Open Access Journals (Sweden)

    Jessica L. Yorzinski

    2018-01-01

    Full Text Available Many animals inhabit environments where they experience temperature fluctuations. One way in which animals can adjust to these temperature changes is through behavioral thermoregulation. However, we know little about the thermal benefits of postural changes and the costs they may incur. In this study, we examined the thermoregulatory role of two postures, the head-tuck and leg-tuck posture, in peafowl (Pavo cristatus and evaluated whether the head-tuck posture imposes a predation cost. The heads and legs of peafowl are significantly warmer when the birds exhibit these postures, demonstrating that these postures serve an important thermoregulatory role. In addition, the birds are slower to respond to an approaching threat when they display the head-tuck posture, suggesting that a thermoregulatory posture can limit antipredator behavior.

  18. Feeding and resting postures of wild northern muriquis (Brachyteles hypoxanthus).

    Science.gov (United States)

    Iurck, Maria F; Nowak, Matthew G; Costa, Leny C M; Mendes, Sérgio L; Ford, Susan M; Strier, Karen B

    2013-01-01

    Increased body size in Brachyteles has been regarded as an important evolutionary adaptation that allowed a greater reliance on leaves compared to other more frugivorous Atelidae, but its association with muriqui positional behavior and substrate use is still unknown. Here, we present original data on the feeding and resting postures of the northern muriqui (Brachyteles hypoxanthus) and evaluate predictions about the relationships between body size, postural behavior, and substrate use derived from previously published data for other atelids (e.g. Alouatta, Ateles, and Lagothrix). The study was undertaken from August 2002 to July 2003 on a large group of well-habituated muriquis inhabiting the Reserva Particular do Patrimônio Natural - Felíciano Miguel Abdala in Minas Gerais, Brazil. Consistent with our predictions, we found that B. hypoxanthus was highly suspensory during postural feeding (60.9%) and commonly used tail-hind limb suspension/horizontal tripod (38.0%) or tail-forelimb/hind limb suspension (21.4%). However, although tail-suspensory postures permitted the muriquis to use the terminal canopy and small-sized substrates, these areas were also accessed via tail-assisted above-branch postural behaviors involving multiple substrates. Unexpectedly, tail-suspensory postures were found to be frequently associated with large substrates, tree trunks, and the understory. We suggest that Brachyteles' ability to access food resources from all areas of a feeding tree and from tree crowns at different canopy levels may account for their ability to efficiently exploit food resources in seasonal disturbed forest fragments of the Brazilian Atlantic Forest today. © 2012 Wiley Periodicals, Inc.

  19. Anisotropic gravitational instability

    International Nuclear Information System (INIS)

    Polyachenko, V.L.; Fridman, A.M.

    1988-01-01

    Exact solutions of stability problems are obtained for two anisotropic gravitational systems of different geometries - a layer of finite thickness at rest and a rotating cylinder of finite radius. It is shown that the anisotropic gravitational instability which develops in both cases is of Jeans type. However, in contrast to the classical aperiodic Jeans instability, this instability is oscillatory. The physics of the anisotropic gravitational instability is investigated. It is shown that in a gravitating layer this instability is due, in particular, to excitation of previously unknown interchange-Jeans modes. In the cylinder, the oscillatory Jeans instability is associated with excitation of a rotational branch, this also being responsible for the beam gravitational instability. This is the reason why this instability and the anisotropic gravitational instability have so much in common

  20. Comparison of postural stability between injured and uninjured ballet dancers.

    Science.gov (United States)

    Lin, Cheng-Feng; Lee, I-Jung; Liao, Jung-Hsien; Wu, Hong-Wen; Su, Fong-Chin

    2011-06-01

    Ballet movements require a limited base of support; thus, ballet dancers require a high level of postural control. However, postural stability in ballet dancers is still unclear and needs to be understood. To evaluate ballet dancers' postural stability in performing single-leg standing, the en pointe task, and the first and fifth positions and to determine differences in task performance among healthy nondancers, healthy dancers, and dancers with ankle sprains. Controlled laboratory study. Injured dancers, uninjured dancers, and nondancers were recruited for this study (N = 33 age-matched participants; n= 11 per group). The tasks tested were single-leg standing with eyes open and closed, first position, fifth position, and en pointe. Center of pressure parameters were calculated from the ground-reaction force collected with 1 force plate. Analysis of variance was used to assess the differences of center of pressure parameters among 3 groups in single-leg standing; independent t test was used to examine the differences of center of pressure parameters between injured and uninjured dancers. During single-leg standing, injured dancers had significantly greater maximum displacement in the medial-lateral direction and total trajectory of center of pressure, compared with the uninjured dancers and nondancers. During the first and fifth positions, the injured dancers demonstrated significantly greater standard deviation of center of pressure position in the medial-lateral and anterior-posterior directions, compared with the uninjured dancers. During en pointe, the injured dancers had significantly greater maximum displacement in the medial-lateral direction and the anterior-posterior direction, compared with the uninjured dancers. The injured and uninjured dancers demonstrated differences in postural stability in the medial-lateral direction during single-leg standing and the ballet postures. Although the injured dancers received ballet training, their postural stability

  1. Thermoregulatory postures limit antipredator responses in peafowl

    OpenAIRE

    Jessica L. Yorzinski; Jennifer Lam; Rachel Schultz; Melissa Davis

    2018-01-01

    Many animals inhabit environments where they experience temperature fluctuations. One way in which animals can adjust to these temperature changes is through behavioral thermoregulation. However, we know little about the thermal benefits of postural changes and the costs they may incur. In this study, we examined the thermoregulatory role of two postures, the head-tuck and leg-tuck posture, in peafowl (Pavo cristatus) and evaluated whether the head-tuck posture imposes a predation cost. The h...

  2. Measuring postural sway in sitting

    DEFF Research Database (Denmark)

    Curtis, Derek John; Hansen, Lisbeth; Luun, Malene

    2015-01-01

    group appeared to result from an equally stable trunk supported on a less stable pelvis. Mediolateral marker sway and intersegmental angular sway showed a clearer age dependency. Trunk postural control does not appear to differ between children older and younger than 10 years old, but sagittal plane...... and younger than 10 years old, participated in this study. The children sat unsupported for 30 s while their posture and sway were quantified using stereophotogrammetry. The tendency in both age groups was to sit with a backward tilted pelvis and a kyphotic trunk. The sitting position was most varied...

  3. Postural Control in Children with Autism.

    Science.gov (United States)

    Kohen-Raz, Reuven; And Others

    1992-01-01

    Postural control was evaluated in 91 autistic, 166 normal, and 18 mentally retarded children using a computerized posturographic procedure. In comparison to normal children, the autistic subjects were less likely to exhibit age-related changes in postural performance, and postures were more variable and less stable. (Author/JDD)

  4. Automated Assessment of Postural Stability (AAPS)

    Science.gov (United States)

    2016-10-01

    performed a battery of standard clinical tests of dynamic posture, whereas the fourth subject performed the stereotyped postures (e.g. movements restricted...Processing & Control [2] Napoli A, Ward C, Glass S, Tucker C, Obeid I (2016) “Automated Assessment of Postural Stability System,” IEEE Engineering in

  5. Greater autonomy at work

    NARCIS (Netherlands)

    Houtman, I.L.D.

    2004-01-01

    In the past 10 years, workers in the Netherlands increasingly report more decision-making power in their work. This is important for an economy in recession and where workers face greater work demands. It makes work more interesting, creates a healthier work environment, and provides opportunities

  6. The effects of anxiety and external attentional focus on postural control in patients with Parkinson's disease

    Science.gov (United States)

    Jazaeri, Seyede Zohreh; Azad, Akram; Mehdizadeh, Hajar; Habibi, Seyed Amirhassan; Mandehgary Najafabadi, Mahbubeh; Saberi, Zakieh Sadat; Rahimzadegan, Hawre; Moradi, Saeed; Behzadipour, Saeed; Parnianpour, Mohamad; Khalaf, Kinda

    2018-01-01

    Background Although anxiety is a common non-motor outcome of Parkinson's disease (PD) affecting 40% of patients, little attention has been paid so far to its effects on balance impairment and postural control. Improvement of postural control through focusing on the environment (i.e. external focus) has been reported, but the role of anxiety, as a confounding variable, remains unclear. Objectives This study aimed to investigate the influence of anxiety and attentional focus instruction on the standing postural control of PD patients. Methods Thirty-four patients with PD (17 with high anxiety (HA-PD) and 17 with low anxiety (LA-PD)), as well as 17 gender- and age-matched healthy control subjects (HC) participated in the study. Postural control was evaluated using a combination of two levels of postural difficulty (standing on a rigid force plate surface with open eyes (RO) and standing on a foam surface with open eyes (FO)), as well as three attentional focus instructions (internal, external and no focus). Results Only the HA-PD group demonstrated significant postural control impairment as compared to the control, as indicated by significantly greater postural sway measures. Moreover, external focus significantly reduced postural sway in all participants especially during the FO condition. Conclusion The results of the current study provide evidence that anxiety influences balance control and postural stability in patients with PD, particularly those with high levels of anxiety. The results also confirmed that external focus is a potential strategy that significantly improves the postural control of these patients. Further investigation of clinical applicability is warranted towards developing effective therapeutic and rehabilitative treatment plans. PMID:29390029

  7. The effects of anxiety and external attentional focus on postural control in patients with Parkinson's disease.

    Science.gov (United States)

    Jazaeri, Seyede Zohreh; Azad, Akram; Mehdizadeh, Hajar; Habibi, Seyed Amirhassan; Mandehgary Najafabadi, Mahbubeh; Saberi, Zakieh Sadat; Rahimzadegan, Hawre; Moradi, Saeed; Behzadipour, Saeed; Parnianpour, Mohamad; Taghizadeh, Ghorban; Khalaf, Kinda

    2018-01-01

    Although anxiety is a common non-motor outcome of Parkinson's disease (PD) affecting 40% of patients, little attention has been paid so far to its effects on balance impairment and postural control. Improvement of postural control through focusing on the environment (i.e. external focus) has been reported, but the role of anxiety, as a confounding variable, remains unclear. This study aimed to investigate the influence of anxiety and attentional focus instruction on the standing postural control of PD patients. Thirty-four patients with PD (17 with high anxiety (HA-PD) and 17 with low anxiety (LA-PD)), as well as 17 gender- and age-matched healthy control subjects (HC) participated in the study. Postural control was evaluated using a combination of two levels of postural difficulty (standing on a rigid force plate surface with open eyes (RO) and standing on a foam surface with open eyes (FO)), as well as three attentional focus instructions (internal, external and no focus). Only the HA-PD group demonstrated significant postural control impairment as compared to the control, as indicated by significantly greater postural sway measures. Moreover, external focus significantly reduced postural sway in all participants especially during the FO condition. The results of the current study provide evidence that anxiety influences balance control and postural stability in patients with PD, particularly those with high levels of anxiety. The results also confirmed that external focus is a potential strategy that significantly improves the postural control of these patients. Further investigation of clinical applicability is warranted towards developing effective therapeutic and rehabilitative treatment plans.

  8. Corona-induced electrohydrodynamic instabilities in low conducting liquids

    Energy Technology Data Exchange (ETDEWEB)

    Vega, F.; Perez, A.T. [Depto. Electronica y Electromagnetismo, Facultad de Fisica, Universidad de Sevilla, Avda. Reina Mercedes, s/n. 41012, Sevilla (Spain)

    2003-06-01

    The rose-window electrohydrodynamic (EHD) instability has been observed when a perpendicular field with an additional unipolar ion injection is applied onto a low conducting liquid surface. This instability has a characteristic pattern with cells five to 10 times greater than those observed in volume instabilities caused by unipolar injection. We have used corona discharge from a metallic point to perform some measurements of the rose-window instability in low conducting liquids. The results are compared to the linear theoretical criterion for an ohmic liquid. They confirmed that the minimum voltage for this instability is much lower than that for the interfacial instability in high conducting liquids. This was predicted theoretically in the dependence of the critical voltage as a function of the non-dimensional conductivity. It is shown that in a non-ohmic liquid the rose window appears as a secondary instability after the volume instability. (orig.)

  9. Effects of the anchor system on postural control in older Adults

    Directory of Open Access Journals (Sweden)

    Eliane Mauerberg de Castro

    2012-03-01

    Full Text Available Falls are common during aging, and can have drastic consequences. Within this context, maintaining the ability to balance plays an essential role in enabling older adults to continue to perform their daily activities. Therefore, the use of interventional and treatment tools for development of balance becomes essential. The objective of this study was to analyze the anchor system as a potential tool for decreasing body sway in older and young adults. Older adults had more postural sway than their young counterparts. The absence of visual information led to larger instability in both groups. The anchor system improved postural stability of both groups. Thus, it may be a useful tool for posture stabilization in old and young adults.

  10. Postural control during one-leg stance in active and sedentary older people

    Directory of Open Access Journals (Sweden)

    Leonardo George Victorio Victor

    2014-09-01

    Full Text Available Physical inactivity and aging are functional disability factors for older individuals, causing loss of balance and increasing the risk of falls. The purpose of this study was to compare the balance of physically independent older individuals, both participants and non-participants in a regular exercise program. Fifty six physically independent older participants were divided into G1ACTIVE = 28 individuals who participate in a regular exercise program and G2SEDENTARY = 28 individuals who did not participate in any physical exercise program. All participants underwent an eyes-open during one-leg balance test on a force platform. The postural oscillation parameters included center of pressure (COP; sway mean velocity and frequency of COP oscillations. G2 SEDENTARY showed higher postural instability than G1ACTIVE. Significant differences were observed for the main balance parameters. The results of this study support the concept that participation in regular physical activity is beneficial for postural balance of older individuals.

  11. Visual Vection does not Perturb Squatting Posture

    Directory of Open Access Journals (Sweden)

    Dietrich Gilles

    2011-12-01

    Full Text Available Vision contributes fundamentally to the control of the standing posture. The illusion of self motion falsely perceived (vection increases postural sway while standing. In this paper we examine the effect of vection on both standing and deep squatting with the hypothesis that the squatting posture should not be disturbed by the conflict of sensory information due to vection. The results show that standing posture only was affected by the visual stimuli. The widespread use of squatting for work as well as rest could be due in part to this lack of effect of sensory perturbation on postural stability.

  12. Sectoral Diversification as Insurance against Economic Instability

    OpenAIRE

    Jan Kluge

    2015-01-01

    This paper examines the extent to which sectoral diversification can act as an insurance mechanism against fluctuations in regional gross value added growth rates. I apply portfolio theory to the growth-instability properties of German districts. Furthermore, I define a comprehensive diversification measure and use Stochastic Frontier Analysis in order to estimate whether diversification allows regions to achieve more efficient growth-instability combinations, i.e., greater stability at given...

  13. Physiological Mechanisms Mediating the Coupling between Heart Period and Arterial Pressure in Response to Postural Changes in Humans

    NARCIS (Netherlands)

    Silvani, A.; Calandra-Buonaura, G.; Johnson, B.D.; Helmond, N. van; Barletta, G.; Cecere, A.G.; Joyner, M.J.; Cortelli, P.

    2017-01-01

    The upright posture strengthens the coupling between heart period (HP) and systolic arterial pressure (SAP) consistently with a greater contribution of the arterial baroreflex to cardiac control, while paradoxically decreasing cardiac baroreflex sensitivity (cBRS). To investigate the physiological

  14. Instabilities in inhomogeneous plasma

    International Nuclear Information System (INIS)

    Mikhailovsky, A.B.

    1983-01-01

    The plasma inhomogeneity across the magnetic field causes a wide class of instabilities which are called instabilities of an inhomogeneous plasma or gradient instabilities. The instabilities that can be studied in the approximation of a magnetic field with parallel straight field lines are treated first, followed by a discussion of the influence of shear on these instabilities. The instabilities of a weakly inhomogeneous plasma with the Maxwellian velocity distribution of particles caused by the density and temperature gradients are often called drift instabilities, and the corresponding types of perturbations are the drift waves. An elementary theory of drift instabilities is presented, based on the simplest equations of motion of particles in the field of low-frequency and long-wavelength perturbations. Following that is a more complete theory of inhomogeneous collisionless plasma instabilities which uses the permittivity tensor and, in the case of electrostatic perturbations, the scalar of permittivity. The results are used to study the instabilities of a strongly inhomogeneous plasma. The instabilities of a plasma in crossed fields are discussed and the electromagnetic instabilities of plasma with finite and high pressure are described. (Auth.)

  15. Relationship Between Postural Control and Restricted, Repetitive Behaviors in Autism Spectrum Disorders

    Directory of Open Access Journals (Sweden)

    Krestin eRadonovich

    2013-05-01

    Full Text Available Restricted, repetitive behaviors (RRBs are one of the core diagnostic criteria of autism spectrum disorders (ASD, and include simple repetitive motor behaviors and more complex cognitive behaviors, such as compulsions and restricted interests. In addition to the core symptoms, impaired movement is often observed in ASD. Research suggests that the postural system in individuals with ASD is immature and may never reach adult levels. RRBs have been related to postural sway in individuals with mental retardation.Our goals were to determine whether subjects with ASD had greater postural sway and whether RBS-R scores were related to the magnitude of postural sway. We compared the center of pressure (COP sway area during quiet stance with scores on the Repetitive Behavior Scale-Revised (RBS-R in children with ASD and typically developing controls (TD ages 3-16. All subjects had Nonverbal IQ>70. Subjects performed four quiet stance trials at a self–selected stance width for 15 seconds. Subjects with ASD had greater postural sway area compared to controls. Not surprisingly, subjects with ASD exhibited greater frequencies and intensities of RRBs overall and on all 6 subscales. Further, there was a positive correlation between postural sway area and presence of RRBs. Interestingly, results of the postural sway area for the ASD group suggests that roughly half of the ASD subjects scored comparable to TD controls, whereas the other half scored >2 SD worse. Motor impaired children did not have significantly worse IQ scores, but were younger and had more RRBs.Results support previous findings of relationships between RRBs and postural control. It appears that motor control impairments may characterize a subset of individuals with ASD. Better delineation of motor control abilities in individuals with ASD will be important to help explain variations of abilities in ASD, inform treatment, and guide examination of underlying neural involvement in this diverse

  16. 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

  17. Influence of deep brain stimulation on postural stability in patients with Parkinson disease

    OpenAIRE

    Zelenková, Jana

    2012-01-01

    Parkinson's disease is a neurodegenerative disease of the basal ganglia. Its main symptoms are rigidity, tremor, bradykinesia, hypokinesia and postural instability. One possible way how to infuence diseases is neurosurgical treatment - deep brain stimulation. The principle is the implantation of electrodes in the basal ganglia and modulation of activity of the basal ganglia circuits due to electrical stimulation. Stimulation affects the motor symptoms of Parkinson's disease. This thesis deals...

  18. Greater-confinement disposal

    International Nuclear Information System (INIS)

    Trevorrow, L.E.; Schubert, J.P.

    1989-01-01

    Greater-confinement disposal (GCD) is a general term for low-level waste (LLW) disposal technologies that employ natural and/or engineered barriers and provide a degree of confinement greater than that of shallow-land burial (SLB) but possibly less than that of a geologic repository. Thus GCD is associated with lower risk/hazard ratios than SLB. Although any number of disposal technologies might satisfy the definition of GCD, eight have been selected for consideration in this discussion. These technologies include: (1) earth-covered tumuli, (2) concrete structures, both above and below grade, (3) deep trenches, (4) augered shafts, (5) rock cavities, (6) abandoned mines, (7) high-integrity containers, and (8) hydrofracture. Each of these technologies employ several operations that are mature,however, some are at more advanced stages of development and demonstration than others. Each is defined and further described by information on design, advantages and disadvantages, special equipment requirements, and characteristic operations such as construction, waste emplacement, and closure

  19. Dose postural control improve following application of transcutaneous electrical nerve stimulation in diabetic peripheral neuropathic patients? A randomized placebo control trial.

    Science.gov (United States)

    Saadat, Z; Rojhani-Shirazi, Z; Abbasi, L

    2017-12-01

    peripheral neuropathy is the most common problem of diabetes. Neuropathy leads to lower extremity somatosensory deficits and postural instability in these patients. However, there are not sufficient evidences for improving postural control in these patients. To investigate the effects of transcutaneous electrical nerve stimulation (TENS) on postural control in patients with diabetic neuropathy. Twenty eighth patients with diabetic neuropathy (40-55 Y/O) participated in this RCT study. Fourteen patients in case group received TENS and sham TENS was used for control group. Force plate platform was used to extract sway velocity and COP displacement parameters for postural control evaluation. The mean sway velocity and center of pressure displacement along the mediolateral and anteroposterior axes were not significantly different between two groups after TENS application (p>0.05). Application of 5min high frequency TENS on the knee joint could not improve postural control in patients with diabetic neuropathy. Copyright © 2017. Published by Elsevier Ltd.

  20. What is the most effective posture to conduct vibration from the lower to the upper extremities during whole-body vibration exercise?

    Directory of Open Access Journals (Sweden)

    Tsukahara Y

    2016-01-01

    Full Text Available Yuka Tsukahara, Jun Iwamoto, Kosui Iwashita, Takuma Shinjo, Koichiro Azuma, Hideo MatsumotoInstitute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan Background: Whole-body vibration (WBV exercise is widely used for training and rehabilitation. However, the optimal posture for training both the upper and lower extremities simultaneously remains to be established. Objectives: The objective of this study was to search for an effective posture to conduct vibration from the lower to the upper extremities while performing WBV exercises without any adverse effects. Methods: Twelve healthy volunteers (age: 22–34 years were enrolled in the study. To measure the magnitude of vibration, four accelerometers were attached to the upper arm, back, thigh, and calf of each subject. Vibrations were produced using a WBV platform (Galileo 900 with an amplitude of 4 mm at two frequencies, 15 and 30 Hz. The following three postures were examined: posture A, standing posture with the knees flexed at 30°; posture B, crouching position with no direct contact between the knees and elbows; and posture C, crouching position with direct contact between the knees and elbows. The ratio of the magnitude of vibration at the thigh, back, and upper arm relative to that at the calf was used as an index of vibration conduction. Results: Posture B was associated with a greater magnitude of vibration to the calf than posture A at 15 Hz, and postures B and C were associated with greater magnitudes of vibration than posture A at 30 Hz. Posture C was associated with a vibration conduction to the upper arm that was 4.62 times and 8.26 times greater than that for posture A at 15 and 30 Hz, respectively. Conclusion: This study revealed that a crouching position on a WBV platform with direct contact between the knees and elbows was effective for conducting vibration from the lower to the upper extremities. Keywords: whole-body vibration exercise, upper

  1. MODIFIED PATH METHODOLOGY FOR OBTAINING INTERVAL-SCALED POSTURAL ASSESSMENTS OF FARMWORKERS.

    Science.gov (United States)

    Garrison, Emma B; Dropkin, Jonathan; Russell, Rebecca; Jenkins, Paul

    2018-01-29

    Agricultural workers perform tasks that frequently require awkward and extreme postures that are associated with musculoskeletal disorders (MSDs). The PATH (Posture, Activity, Tools, Handling) system currently provides a sound methodology for quantifying workers' exposure to these awkward postures on an ordinal scale of measurement, which places restrictions on the choice of analytic methods. This study reports a modification of the PATH methodology that instead captures these postures as degrees of flexion, an interval-scaled measurement. Rather than making live observations in the field, as in PATH, the postural assessments were performed on photographs using ImageJ photo analysis software. Capturing the postures in photographs permitted more careful measurement of the degrees of flexion. The current PATH methodology requires that the observer in the field be trained in the use of PATH, whereas the single photographer used in this modification requires only sufficient training to maintain the proper camera angle. Ultimately, these interval-scale measurements could be combined with other quantitative measures, such as those produced by electromyograms (EMGs), to provide more sophisticated estimates of future risk for MSDs. Further, these data can provide a baseline from which the effects of interventions designed to reduce hazardous postures can be calculated with greater precision. Copyright© by the American Society of Agricultural Engineers.

  2. Investigation of postural edema in the lower extremities of traffic control workers

    Directory of Open Access Journals (Sweden)

    Ana Paula Nunes Pereira Brito

    2013-12-01

    Full Text Available OBJECTIVE: Determine the prevalence of postural edema and investigate whether working posture - sitting down or standing up - affect its frequency. METHODS: Sixteen traffic control agents were assessed by water displacement volumetry and the results were analyzed in two groups, depending on working posture. Those who worked standing up for more than 4 hours were allocated to the SU group and those who worked sitting down for more than 4 hours were allocated to the SD group. Each worker was assessed before and after their working shift for three consecutive days. Data were analyzed using ANOVA and the test of equality of two proportions. The significance level was set at p ≤ 0.05. The assessment showed that members of both groups had postural edema of the lower extremities (p ≤ 0.001. RESULTS: When the frequency of postural edema was compared across groups, a trend was observed for greater edema formation in the SU group than in the SD group, although without statistically significant difference. CONCLUSION: It was concluded that traffic control agents suffer postural edema after 4 hours working in either of the postures investigated although with a predominance of edema formation among those who work standing up.

  3. The influence of gravity on regional lung blood flow in humans: SPECT in the upright and head-down posture.

    Science.gov (United States)

    Ax, M; Sanchez-Crespo, A; Lindahl, S G E; Mure, M; Petersson, J

    2017-06-01

    Previous studies in humans have shown that gravity has little influence on the distribution of lung blood flow while changing posture from supine to prone. This study aimed to evaluate the maximal influence of posture by comparison of regional lung blood flow in the upright and head-down posture in 8 healthy volunteers, using a tilt table. Regional lung blood flow was marked by intravenous injection of macroaggregates of human albumin labeled with 99m Tc or 113m In, in the upright and head-down posture, respectively, during tidal breathing. Both radiotracers remain fixed in the lung after administration. The distribution of radioactivity was mapped using quantitative single photon emission computed tomography (SPECT) corrected for attenuation and scatter. All images were obtained supine during tidal breathing. A shift from upright to the head-down posture caused a clear redistribution of blood flow from basal to apical regions. We conclude that posture plays a role for the distribution of lung blood flow in upright humans, and that the influence of posture, and thereby gravity, is much greater in the upright and head-down posture than in horizontal postures. However, the results of the study demonstrate that lung structure is the main determinant of regional blood flow and gravity is a secondary contributor to the distribution of lung blood flow in the upright and head-down positions. NEW & NOTEWORTHY Using a dual-isotope quantitative SPECT method, we demonstrated that although a shift in posture redistributes blood flow in the direction of gravity, the results are also consistent with lung structure being a greater determinant of regional blood flow than gravity. To our knowledge, this is the first study to use modern imaging methods to quantify the shift in regional lung blood flow in humans at a change between the upright and head-down postures. Copyright © 2017 the American Physiological Society.

  4. More features, greater connectivity.

    Science.gov (United States)

    Hunt, Sarah

    2015-09-01

    Changes in our political infrastructure, the continuing frailties of our economy, and a stark growth in population, have greatly impacted upon the perceived stability of the NHS. Healthcare teams have had to adapt to these changes, and so too have the technologies upon which they rely to deliver first-class patient care. Here Sarah Hunt, marketing co-ordinator at Aid Call, assesses how the changing healthcare environment has affected one of its fundamental technologies - the nurse call system, argues the case for wireless such systems in terms of what the company claims is greater adaptability to changing needs, and considers the ever-wider range of features and functions available from today's nurse call equipment, particularly via connectivity with both mobile devices, and ancillaries ranging from enuresis sensors to staff attack alert 'badges'.

  5. Greater oil investment opportunities

    International Nuclear Information System (INIS)

    Arenas, Ismael Enrique

    1997-01-01

    Geologically speaking, Colombia is a very attractive country for the world oil community. According to this philosophy new and important steps are being taken to reinforce the oil sector: Expansion of the exploratory frontier by including a larger number of sedimentary areas, and the adoption of innovative contracting instruments. Colombia has to offer, Greater economic incentives for the exploration of new areas to expand the exploratory frontier, stimulation of exploration in areas with prospectivity for small fields. Companies may offer Ecopetrol a participation in production over and above royalties, without it's participating in the investments and costs of these fields, more favorable conditions for natural gas seeking projects, in comparison with those governing the terms for oil

  6. Postural risk assessment of mechanised firewood processing.

    Science.gov (United States)

    Spinelli, Raffaele; Aminti, Giovanni; De Francesco, Fabio

    2017-03-01

    The study assessed the postural risk of mechanised firewood processing with eight machines, representing the main technology solutions available on the market. Assessment was conducted with the Ovako Working posture Analysis System (OWAS) on 1000 still frames randomly extracted from videotaped work samples. The postural risk associated with firewood processing was variable and associated with technology type. Simple, manually operated new machines incurred a higher postural risk compared with semi- or fully automatic machines. In contrast, new semi-automatic and automatic machines were generally free from postural risk. In all cases, attention should be paid to postural risk that may occur during blockage resolution. The study did not cover the postural risk of firewood processing sites as a whole. The study provided useful information for selecting firewood processing machinery and for improving firewood machinery design, as part of a more articulate strategy aimed at enhancing the safety of firewood processing work sites. Practitioner Summary: The postural risk associated with mechanised firewood processing (eg cutting and splitting) depends on the type of equipment. Postural risk is highest (OWAS Action Category 2) with new in-line machines, designed for operation by a single worker. Fully automatic machines present minimum postural risk, except during blockage resolution.

  7. STEADFAST: Psychotherapeutic Intervention Improves Postural Strategy of Somatoform Vertigo and Dizziness

    Science.gov (United States)

    Best, Christoph; Tschan, Regine; Stieber, Nikola; Beutel, Manfred E.; Eckhardt-Henn, Annegret; Dieterich, Marianne

    2015-01-01

    Patients with somatoform vertigo and dizziness (SVD) disorders often report instability of stance or gait and fear of falling. Posturographic measurements indeed indicated a pathological postural strategy. Our goal was to evaluate the effectiveness of a psychotherapeutic and psychoeducational short-term intervention (PTI) using static posturography and psychometric examination. Seventeen SVD patients took part in the study. The effects of PTI on SVD were evaluated with quantitative static posturography. As primary endpoint a quotient characterizing the relation between horizontal and vertical sway was calculated (Q H/V), reflecting the individual postural strategy. Results of static posturography were compared to those of age- and gender-matched healthy volunteers (n = 28); baseline measurements were compared to results after PTI. The secondary endpoint was the participation-limiting consequences of SVD as measured by the Vertigo Handicap Questionnaire (VHQ). Compared to the healthy volunteers, the patients with SVD showed a postural strategy characterized by stiffening-up that resulted in a significantly reduced body sway quotient before PTI (patients: Q H/V = 0.31 versus controls: Q H/V = 0.38; p = 0.022). After PTI the postural behavior normalized, and psychological distress was reduced. PTI therefore appears to modify pathological balance behaviour. The postural strategy of patients with SVD possibly results from anxious anticipatory cocontraction of the antigravity muscles. PMID:26843786

  8. STEADFAST: Psychotherapeutic Intervention Improves Postural Strategy of Somatoform Vertigo and Dizziness

    Directory of Open Access Journals (Sweden)

    Christoph Best

    2015-01-01

    Full Text Available Patients with somatoform vertigo and dizziness (SVD disorders often report instability of stance or gait and fear of falling. Posturographic measurements indeed indicated a pathological postural strategy. Our goal was to evaluate the effectiveness of a psychotherapeutic and psychoeducational short-term intervention (PTI using static posturography and psychometric examination. Seventeen SVD patients took part in the study. The effects of PTI on SVD were evaluated with quantitative static posturography. As primary endpoint a quotient characterizing the relation between horizontal and vertical sway was calculated (QH/V, reflecting the individual postural strategy. Results of static posturography were compared to those of age- and gender-matched healthy volunteers (n=28; baseline measurements were compared to results after PTI. The secondary endpoint was the participation-limiting consequences of SVD as measured by the Vertigo Handicap Questionnaire (VHQ. Compared to the healthy volunteers, the patients with SVD showed a postural strategy characterized by stiffening-up that resulted in a significantly reduced body sway quotient before PTI (patients: QH/V=0.31 versus controls: QH/V=0.38; p=0.022. After PTI the postural behavior normalized, and psychological distress was reduced. PTI therefore appears to modify pathological balance behaviour. The postural strategy of patients with SVD possibly results from anxious anticipatory cocontraction of the antigravity muscles.

  9. Postural control in blind subjects.

    Science.gov (United States)

    Soares, Antonio Vinicius; Oliveira, Cláudia Silva Remor de; Knabben, Rodrigo José; Domenech, Susana Cristina; Borges Junior, Noe Gomes

    2011-12-01

    To analyze postural control in acquired and congenitally blind adults. A total of 40 visually impaired adults participated in the research, divided into 2 groups, 20 with acquired blindness and 20 with congenital blindness - 21 males and 19 females, mean age 35.8 ± 10.8. The Brazilian version of Berg Balance Scale and the motor domain of functional independence measure were utilized. On Berg Balance Scale the mean for acquired blindness was 54.0 ± 2.4 and 54.4 ± 2.5 for congenitally blind subjects; on functional independence measure the mean for acquired blind group was 87.1 ± 4.8 and 87.3 ± 2.3 for congenitally blind group. Based upon the scale used the results suggest the ability to control posture can be developed by compensatory mechanisms and it is not affected by visual loss in congenitally and acquired blindness.

  10. Postural control in blind subjects

    Directory of Open Access Journals (Sweden)

    Antonio Vinicius Soares

    2011-12-01

    Full Text Available Objective: To analyze postural control in acquired and congenitally blind adults. Methods: A total of 40 visually impaired adults participated in the research, divided into 2 groups, 20 with acquired blindness and 20 with congenital blindness - 21 males and 19 females, mean age 35.8 ± 10.8. The Brazilian version of Berg Balance Scale and the motor domain of functional independence measure were utilized. Results: On Berg Balance Scale the mean for acquired blindness was 54.0 ± 2.4 and 54.4 ± 2.5 for congenitally blind subjects; on functional independence measure the mean for acquired blind group was 87.1 ± 4.8 and 87.3 ± 2.3 for congenitally blind group. Conclusion: Based upon the scale used the results suggest the ability to control posture can be developed by compensatory mechanisms and it is not affected by visual loss in congenitally and acquired blindness.

  11. Risk factors associated with structural postural changes in the spinal column of children and adolescents

    Directory of Open Access Journals (Sweden)

    Juliana Adami Sedrez

    2015-03-01

    Full Text Available OBJECTIVE: To investigate the association between behavioral risk factors, specifically postural habits, with the presence of structural changes in the spinal column of children and adolescents. METHODS: 59 students were evaluated through the self-reporting Back Pain and Body Posture Evaluation Instrument and spinal panoramic radiographic examination. Spine curvatures were classified based on Cobb angles, as normal or altered in the saggital plane and as normal or scoliotic in the frontal plane. Data were analyzed using SPSS 18.0, based on descriptive statistics and chi-square association test (a=0,05. RESULTS: The prevalence of postural changes was 79.7% (n=47, of which 47.5% (n=28 showed frontal plane changes and 61% (n=36 sagital plane changes. Significant association was found between the presence of thoracic kyphosis and female gender, practice of physical exercises only once or twice a week, sleep time greater than 10 hours, inadequate postures when sitting on a seat and sitting down to write, and how school supplies are carried. Lumbar lordosis was associated with the inadequate way of carrying the school backpack (asymmetric; and scoliosis was associated wuth the practice of competitive sports and sleep time greater than 10 hours. CONCLUSIONS: Lifestyle may be associated with postural changes. It is important to develop health policies in order to reduce the prevalence of postural changes, by decreasing the associated risk factors.

  12. Cerebral palsy: Influence of TheraTogs ® on gait, posture and in functional performance

    Directory of Open Access Journals (Sweden)

    Raquel Ehlert

    Full Text Available Abstract Introduction: For children with cerebral palsy, orthoses take an important role in improving posture, gait, functional performance and preventing secondary musculoskeletal disorders. Objective: To evaluate the influence of TheraTogs® on the posture, distribution of plantar pressure during gait and functional performance of a child with spastic diplegia cerebral palsy. Methods: A quantitative evaluation was carried out on a case study in which an 11-year-old child diagnosed with diplegic cerebral palsy underwent postural assessment through the Postural Assessment Software (PAS, plantar pressure distribution assessment during barefoot gait through the Emed-X system, before and after the intervention period of 8 weeks and functional assessment (Pediatric Evaluation of Disability Inventory - PEDI, with and without TheraTogs®. Results: In posture, TheraTogs® had greater influence on hip extension and this change was greater during its use. In the plantar pressure distribution assessment, an increase in posteriorization of plantar pressure occurred in the initial contact, the performance of the push-off phase and initial swing phase improved. In functionality, the child showed improvements in mobility, however, their self-care ability with TheraTogs® was reduced. Conclusion: Although improvements in posture, gait and functionality were verified with the use of TheraTogs®, the excessive heat, difficulties in toileting and self-care were disadvantages in wearing TheraTogs®.

  13. Instability after total hip arthroplasty

    Science.gov (United States)

    Werner, Brian C; Brown, Thomas E

    2012-01-01

    Instability following total hip arthroplasty (THA) is an unfortunately frequent and serious problem that requires thorough evaluation and preoperative planning before surgical intervention. Prevention through optimal index surgery is of great importance, as the management of an unstable THA is challenging even for an experienced joints surgeon. However, even after well-planned surgery, a significant incidence of recurrent instability still exists. Non-operative management is often successful if the components are well-fixed and correctly positioned in the absence of neurocognitive disorders. If conservative management fails, surgical options include revision of malpositioned components; exchange of modular components such as the femoral head and acetabular liner; bipolar arthroplasty; tripolar arthroplasty; use of a larger femoral head; use of a constrained liner; soft tissue reinforcement and advancement of the greater trochanter. PMID:22919568

  14. Feedback control of resistive instabilities

    International Nuclear Information System (INIS)

    White, R.B.; Rutherford, P.H.; Furth, H.P.; Park, W.; Chen, L.

    1985-12-01

    Resistive instabilities are responsible for much of the global behavior and the determination of the possible domains of operation of tokamaks. Their successful control could have definite advantages, even making available new regimes of operation. Elimination of sawtoothing might allow operation with higher currents and more peaked current profiles, with q on axis well below unity. In this work different feedback schemes are explored. Simple analytical derivations of the effects of local heating and current drive feedback are presented. Although control of modes with m greater than or equal to 2 is fairly straightforward, the control of the m = 1 mode is more difficult because of its proximity to ideal instability. The most promising scheme utilizes high energy trapped particles. 20 refs., 3 figs

  15. Postural Stabilization Strategies to Motor Contagion Induced by Action Observation Are Impaired in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Elisa Pelosin

    2018-03-01

    Full Text Available Postural reactions can be influenced by concomitant tasks or different contexts and are modulated by a higher order motor control. Recent studies investigated postural changes determined by motor contagion induced by action observation (chameleon effect showing that observing a model in postural disequilibrium induces an increase in healthy subjects’ body sway. Parkinson’s disease (PD is associated with postural instability and impairments in cognitively controlled balance tasks. However, no studies investigated if viewing postural imbalance might influence postural stability in PD and if patients are able to inhibit a visual postural perturbation. In this study, an action observation paradigm for assessing postural reaction to motor contagion in PD subjects and healthy older adults was used. Postural stability changes were measured during the observation of a static stimulus (control condition and during a point-light display of a gymnast balancing on a rope (biological stimulus. Our results showed that, during the observation of the biological stimulus, sway area and antero-posterior and medio-lateral displacements of center of pressure significantly increased only in PD participants, whereas correct stabilization reactions were present in elderly subjects. These results demonstrate that PD leads to a decreased capacity to control automatic imitative tendencies induced by motor contagion. This behavior could be the consequence either of an inability to inhibit automatic imitative tendencies or of the cognitive load requested by the task. Whatever the case, the issue about the ability to inhibit automatic imitative tendencies could be crucial for PD patients since it might increase falls risk and injuries.

  16. Detecting altered postural control after cerebral concussion in athletes with normal postural stability

    OpenAIRE

    Cavanaugh, J; Guskiewicz, K; Giuliani, C; Marshall, S; Mercer, V; Stergiou, N

    2005-01-01

    Objective: To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion.

  17. Common postural defects among music students.

    Science.gov (United States)

    Blanco-Piñeiro, Patricia; Díaz-Pereira, M Pino; Martínez, Aurora

    2015-07-01

    Postural quality during musical performance affects both musculoskeletal health and the quality of the performance. In this study we examined the posture of 100 students at a Higher Conservatory of Music in Spain. By analysing video tapes and photographs of the students while performing, a panel of experts extracted values of 11 variables reflecting aspects of overall postural quality or the postural quality of various parts of the body. The most common postural defects were identified, together with the situations in which they occur. It is concluded that most students incur in unphysiological postures during performance. It is hoped that use of the results of this study will help correct these errors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Craniocervical Posture in Patients with Obstructive Sleep Apnea

    Directory of Open Access Journals (Sweden)

    Piccin, Chaiane Facco

    2016-07-01

    Full Text Available Introduction Obstructive Sleep Apnea (OSA is characterized by repeated episodes of upper airway obstruction during sleep. Objective The objective of this study is to verify the craniofacial characteristics and craniocervical posture of OSA and healthy subjects, determining possible relationships with the apnea/hypopnea index (AHI. Methods This case-control study evaluated 21 subjects with OSA, who comprised the OSA group (OSAG, and 21 healthy subjects, who constituted the control group (CG. Cephalometry analyzed head posture measurements, craniofacial measurements, and air space. Head posture was also assessed by means of photogrammetry. Results The groups were homogeneous regarding gender (12 men and 9 women in each group, age (OSAG = 41.86 ± 11.26 years; GC = 41.19 ± 11.20 years, and body mass index (OSAG = 25.65 ± 2.46 kg/m2; CG = 24.72 ± 3.01 kg/m2. We found significant differences between the groups, with lower average pharyngeal space and greater distance between the hyoid bone and the mandibular plane in OSAG, when compared with CG. A positive correlation was found between higher head hyperextension and head anteriorization, with greater severity of OSA as assessed by AHI. Conclusion OSAG subjects showed changes in craniofacial morphology, with lower average pharyngeal space and greater distance from the hyoid bone to the mandibular plane, as compared with healthy subjects. Moreover, in OSA subjects, the greater the severity of OSA, the greater the head hyperextension and anteriorization.

  19. Assessing Somatosensory Utilization during Unipedal Postural Control

    OpenAIRE

    Goel, Rahul; De Dios, Yiri E.; Gadd, Nichole E.; Caldwell, Erin E.; Peters, Brian T.; Reschke, Millard F.; Bloomberg, Jacob J.; Oddsson, Lars I. E.; Mulavara, Ajitkumar P.

    2017-01-01

    Multisensory—visual, vestibular and somatosensory information is integrated for appropriate postural control. The primary goal of this study was to assess somatosensory utilization during a functional motor task of unipedal postural control, in normal healthy adults. Assessing individual bias in the utilization of individual sensory contributions during postural control may help customization of rehabilitation protocols. In this study, a test paradigm of unipedal stance control in supine orie...

  20. Joint Instability and Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Darryl Blalock

    2015-01-01

    Full Text Available Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA. Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA.

  1. Joint instability and osteoarthritis.

    Science.gov (United States)

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA.

  2. Education and the Prevention of Postural Defects

    Directory of Open Access Journals (Sweden)

    Olchowska-Kotala Agnieszka

    2014-12-01

    Full Text Available Purpose. The aim of this study was to determine: whether and at what stage of education is proper body posture learned, the intention of young adults to participate in activities teaching proper posture, and the effects of factors related with the said intention. Methods. The study involved 430 university students aged 18-24 years. Anthropometric data was collected. Participants completed questionnaires assessing physical activity level (IPAQ and their intention to participate in extracurricular activities teaching proper posture while sitting or walking, proper running technique, corrective gymnastics, or weight loss exercises. A self-assessment of posture, physical fitness, attractiveness, and body satisfaction was also completed. Results. Lower back pain was experienced by 41% of the respondents. Most were taught proper posture-related habits in primary school, followed by secondary school, and then at university. Many students expressed their intention to participate in the extracurricular activities. None of the questionnaire variables were associated with the intention to learn proper walking posture or proper running technique. The intention to participate in classes teaching proper sitting posture was associated with lower back pain in women and low physical activity level in men. In women, a relationship was found between the intention to participate in weight loss exercises and body dissatisfaction, high BMI, and poor self-evaluations of posture and attractiveness. In men, this activity was associated with body dissatisfaction. Conclusions. There is a need for further education on the development of proper postural habits at the university level.

  3. The dentist's operating posture - ergonomic aspects.

    Science.gov (United States)

    Pîrvu, C; Pătraşcu, I; Pîrvu, D; Ionescu, C

    2014-06-15

    The practice of dentistry involves laborious high finesse dental preparations, precision and control in executions that require a particular attention, concentration and patience of the dentist and finally the dentist's physical and mental resistance. The optimal therapeutic approach and the success of practice involve special working conditions for the dentist and his team in an ergonomic environment. The meaning of the posture in ergonomics is the manner in which different parts of the body are located and thus the reports are established between them in order to allow a special task execution. This article discusses the posture adopted by dentists when they work, beginning with the balanced posture and going to different variants of posture. The ideal posture of a dentist gives him, on the one hand the optimal working conditions (access, visibility and control in the mouth) and on the other hand, physical and psychological comfort throughout the execution of the clinical acts. Although the theme of dentist posture is treated with great care and often presented in the undergraduate courses and the continuing education courses on ergonomics in dentistry, many dentists do not know the subject well enough nor the theoretical issues and therefore nor the practical applicability. The risk and perspective of the musculoskeletal disorders related to unbalanced postures should determine the dentists take postural corrective actions and compensation measures in order to limit the negative effects of working in a bad posture.

  4. Postural adaptations to repeated optic flow stimulation in older adults

    Science.gov (United States)

    O’Connor, Kathryn W.; Loughlin, Patrick J.; Redfern, Mark S.; Sparto, Patrick J.

    2008-01-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of three conditions were performed: 1) constant 12 cm optic flow amplitude (24 cm peak-to-peak), 2) constant 4 cm amplitude (8 cm p-t-p), and 3) a transition in amplitude from 4 to 12 cm. The average power of head sway velocity (Pvel) was calculated for consecutive 5 s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the Pvel. Pvel was greater in older adults in all conditions (p Pvel of the older adults decreased significantly between all 3 trials, but decreased only between trial 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12 cm did not significantly change, older adults had an increase in Pvel following the transition, ranging from 6.5 dB for the first trial to 3.4 dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization. PMID:18329878

  5. Resistive instabilities in tokamaks

    International Nuclear Information System (INIS)

    Rutherford, P.H.

    1985-10-01

    Low-m tearing modes constitute the dominant instability problem in present-day tokamaks. In this lecture, the stability criteria for representative current profiles with q(0)-values slightly less than unit are reviewed; ''sawtooth'' reconnection to q(0)-values just at, or slightly exceeding, unity is generally destabilizing to the m = 2, n = 1 and m = 3, n = 2 modes, and severely limits the range of stable profile shapes. Feedback stabilization of m greater than or equal to 2 modes by rf heating or current drive, applied locally at the magnetic islands, appears feasible; feedback by island current drive is much more efficient, in terms of the radio-frequency power required, then feedback by island heating. Feedback stabilization of the m = 1 mode - although yielding particularly beneficial effects for resistive-tearing and high-beta stability by allowing q(0)-values substantially below unity - is more problematical, unless the m = 1 ideal-MHD mode can be made positively stable by strong triangular shaping of the central flux surfaces. Feedback techniques require a detectable, rotating MHD-like signal; the slowing of mode rotation - or the excitation of non-rotating modes - by an imperfectly conducting wall is also discussed

  6. Hydrodynamic instabilities in inertial fusion

    International Nuclear Information System (INIS)

    Hoffman, N.M.

    1994-01-01

    This report discusses topics on hydrodynamics instabilities in inertial confinement: linear analysis of Rayleigh-Taylor instability; ablation-surface instability; bubble rise in late-stage Rayleigh-Taylor instability; and saturation and multimode interactions in intermediate-stage Rayleigh-Taylor instability

  7. Spatial orientation and postural control in patients with Parkinson's disease.

    Science.gov (United States)

    Pawlitzki, E; Schlenstedt, C; Schmidt, N; Rotkirch, I; Gövert, F; Hartwigsen, G; Witt, K

    2018-02-01

    Postural instability is one of the most disabling and risky symptoms of advanced Parkinson's disease (PD). The purpose of this study was to investigate whether and how this is mediated by a centrally impaired spatial orientation. Therefore, we performed a spatial orientation study in 21 PD patients (mean age 68years, SD 8.5 years, 9 women) in a medically on condition and 21 healthy controls (mean age 68.9years, SD 5.5years, 14 women). We compared their spatial responses to the horizontal axis (Sakashita's visual target cancellation task), the vertical axis (bucket-test), the sagittal axis (tilt table test) and postural stability using the Fullerton Advanced Balance Scale (FAB). We found larger deviations on the vertical axis in PD patients, although the direct comparisons of performance in PD patients and healthy controls did not reveal significant differences. While the total scores of the FAB Scale were significantly worse in PD (25.9 points, SD 7.2 points) compared to controls (35.1 points, SD 2.3 points, pbalance control. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Neck pain and postural balance among workers with high postural demands - a cross-sectional study

    DEFF Research Database (Denmark)

    Jørgensen, Marie B.; Skotte, Jørgen H.; Holtermann, Andreas

    2011-01-01

    Neck pain is related to impaired postural balance among patients and is highly prevalent among workers with high postural demands, for example, cleaners. We therefore hypothesised, that cleaners with neck pain suffer from postural dysfunction. This cross-sectional study tested if cleaners with neck...... pain have an impaired postural balance compared with cleaners without neck pain. Postural balance of 194 cleaners with (n = 85) and without (N = 109) neck pain was studied using three different tests. Success or failure to maintain the standing position for 30 s in unilateral stance was recorded...... to cleaners without neck/low back pain (p balance, measured as CEA (p

  9. Genomic instability following irradiation

    International Nuclear Information System (INIS)

    Hacker-Klom, U.B.; Goehde, W.

    2001-01-01

    Ionising irradiation may induce genomic instability. The broad spectrum of stress reactions in eukaryontic cells to irradiation complicates the discovery of cellular targets and pathways inducing genomic instability. Irradiation may initiate genomic instability by deletion of genes controlling stability, by induction of genes stimulating instability and/or by activating endogeneous cellular viruses. Alternatively or additionally it is discussed that the initiation of genomic instability may be a consequence of radiation or other agents independently of DNA damage implying non nuclear targets, e.g. signal cascades. As a further mechanism possibly involved our own results may suggest radiation-induced changes in chromatin structure. Once initiated the process of genomic instability probably is perpetuated by endogeneous processes necessary for proliferation. Genomic instability may be a cause or a consequence of the neoplastic phenotype. As a conclusion from the data available up to now a new interpretation of low level radiation effects for radiation protection and in radiotherapy appears useful. The detection of the molecular mechanisms of genomic instability will be important in this context and may contribute to a better understanding of phenomenons occurring at low doses <10 cSv which are not well understood up to now. (orig.)

  10. Cardiovascular and Postural Control Interactions during Hypergravity: Effects on Cerebral Autoregulation in Males and Females

    Science.gov (United States)

    Goswami, Nandu; Blaber, Andrew; Bareille, Marie-Pierre; Beck, Arnaud; Avan, Paul; Bruner, Michelle; Hinghofer-Szalkay, Helmut

    2012-07-01

    Orthostatic intolerance remains a problem upon return to Earth from the microgravity environment of spaceflight. A variety of conditions including hypovolemia, cerebral vasoconstriction, cerebral or peripheral vascular disease, or cardiac arrhythmias may result in syncope if the person remains upright. Current research indicates that there is a greater dependence on visual and somatosensory information at the beginning of space flight with a decreased otolith gain during prolonged space flight (Herault et al., 2002). The goal of the research is to further our understanding of the fundamental adaptive homeostatic mechanisms involved in gravity related changes in cardiovascular and postural function. Cardiovascular, cerebrovascular, and postural sensory motor control systems in male and female participants before, during, and after exposure to graded levels of hyper-G were investigated. Hypotheses: 1) Activation of skeletal muscle pump will be directly related to the degree of orthostatic stress. 2) Simultaneous measurement of heart rate, blood pressure and postural sway will predict cardio-postural stability. Blood pressure and heart rate (means and variability), postural sway, center of pressure (COP), baroreflex function, calf blood flow, middle cerebral artery blood flow, non-invasive intracranial pressure measurements, and two-breath CO2 were measured. Results from the study will be used to provide an integrated insight into mechanisms of cardio-postural control and cerebral autoregulation, which are important aspects of human health in flights to Moon, Mars and distant planets.

  11. Aging causes a reorganization of cortical and spinal control of posture

    Directory of Open Access Journals (Sweden)

    Selma ePapegaaij

    2014-03-01

    Full Text Available Classical studies in animal preparations suggest a strong role for spinal control of posture. In young adults it is now established that the cerebral cortex contributes to postural control of unperturbed and perturbed standing. The age-related degeneration and accompanying functional changes in the brain, reported so far mainly in conjunction with simple manual motor tasks, may also affect the mechanisms that control complex motor tasks involving posture. This review outlines the age-related structural and functional changes at spinal and cortical levels and provides a mechanistic analysis of how such changes may be linked to the behaviorally manifest postural deficits in old adults. The emerging picture is that the age-related reorganization in motor control during voluntary tasks, characterized by differential modulation of spinal reflexes, greater cortical activation and cortical disinhibition, is also present during postural tasks. We discuss the possibility that this reorganization underlies the increased coactivation and dual task interference reported in elderly. Finally, we propose a model for future studies to unravel the structure-function-behavior relations in postural control and aging.

  12. Comparison of posture among adolescent male volleyball players and non-athletes

    Science.gov (United States)

    2014-01-01

    Due to high training loads and frequently repeated unilateral exercises, several types of sports training can have an impact on the process of posture development in young athletes. The objective of the study was to assess and compare the postures of adolescent male volleyball players and their non-training peers. The study group comprised 104 volleyball players while the control group consisted of 114 non-training individuals aged 14-16 years. Body posture was assessed by the Moiré method. The volleyball players were significantly taller, and had greater body weight and fat-free mass. The analysis of posture relative to symmetry in the frontal and transverse planes did not show any significant differences between the volleyball players and non-athletes. Postural asymmetries were observed in both the volleyball players and the control participants. Lumbar lordosis was significantly less defined in the volleyball players compared to non-training individuals while no difference was observed in thoracic kyphosis. All athletes demonstrated a loss of lumbar lordosis and an increase in thoracic kyphosis. Significant differences in anteroposterior curvature of the spine between the volleyball players and the non-athletes might be associated with both training and body height. Considering the asymmetric spine overloads which frequently occur in sports training, meticulous posture assessment in young athletes seems well justified. PMID:25729154

  13. Comparison of posture among adolescent male volleyball players and non-athlete

    Directory of Open Access Journals (Sweden)

    Małgorzata Grabara

    2014-10-01

    Full Text Available Due to high training loads and frequently repeated unilateral exercises, several types of sports training can have an impact on the process of posture development in young athletes. The objective of the study was to assess and compare the postures of adolescent male volleyball players and their non-training peers. The study group comprised 104 volleyball players while the control group consisted of 114 non-training individuals aged 14-16 years. Body posture was assessed by the Moiré method. The volleyball players were significantly taller, and had greater body weight and fat-free mass. The analysis of posture relative to symmetry in the frontal and transverse planes did not show any significant differences between the volleyball players and non-athletes. Postural asymmetries were observed in both the volleyball players and the control participants. Lumbar lordosis was significantly less defined in the volleyball players compared to non-training individuals while no difference was observed in thoracic kyphosis. All athletes demonstrated a loss of lumbar lordosis and an increase in thoracic kyphosis. Significant differences in anteroposterior curvature of the spine between the volleyball players and the non-athletes might be associated with both training and body height. Considering the asymmetric spine overloads which frequently occur in sports training, meticulous posture assessment in young athletes seems well justified.

  14. Body posture and pulmonary function in mouth and nose breathing children: cross-sectional study

    Directory of Open Access Journals (Sweden)

    Jovana de Moura Milanesi

    Full Text Available Abstract Introduction: Mouth breathing can lead to changes in body posture and pulmonary function. However, the consequences are still inconclusive and a number of studies are controversial. Objective: Evaluate and correlate spirometric parameters and postural measures in mouth breathing children, and compare them to nose breathers. Methods: two groups of 6 to 12 year-old children were evaluated: mouth breathers (MB, n = 55 and nose breathers (NB, n = 45. Spirometry and body posture analysis using photogrammetry (SAPo 0.68® v were carried out. The following spirometric measures were evaluated: peak expiratory flow (PEF, forced expiratory volume in 1 second (FEV1, forced vital capacity (FVC, FEV1/FVC ratio (% and forced expiratory flow between 25% and 75% of FVC (FEF 25-75%. Biophotogrammetric measures analyzed were: horizontal alignment of acromions (HAA and anterior superior iliac spine (HAASIS, Charpy angle, horizontal alignment of the head (HAH, cervical lordosis (CL, thoracic kyphosis (TK, lumbar lordosis (LL, cervical distance (CD and lumbar distance (LD. Results: There were no intergroup differences in spirometric and postural variables. Positive and moderate correlations were found between CL and CD measures with PEF, FEV1, FVC and FEF 25-75%, while weak correlations were observed between lumbar lordosis and PEF, FEV1 and FVC. Conclusion: The breathing mode had no influence on postural and respiratory measures. However, greater forward head posture, with smaller cervical lordosis, was related to higher lung volumes and flows in both groups.

  15. Comparison of posture among adolescent male volleyball players and non-athletes

    Directory of Open Access Journals (Sweden)

    Małgorzata Grabara

    2014-11-01

    Full Text Available Due to high training loads and frequently repeated unilateral exercises, several types of sports training can have an impact on the process of posture development in young athletes. The objective of the study was to assess and compare the postures of adolescent male volleyball players and their non-training peers. The study group comprised 104 volleyball players while the control group consisted of 114 non-training individuals aged 14-16 years. Body posture was assessed by the Moiré method. The volleyball players were significantly taller, and had greater body weight and fat-free mass. The analysis of posture relative to symmetry in the frontal and transverse planes did not show any significant differences between the volleyball players and non-athletes. Postural asymmetries were observed in both the volleyball players and the control participants. Lumbar lordosis was significantly less defined in the volleyball players compared to non-training individuals while no difference was observed in thoracic kyphosis. All athletes demonstrated a loss of lumbar lordosis and an increase in thoracic kyphosis. Significant differences in anteroposterior curvature of the spine between the volleyball players and the non-athletes might be associated with both training and body height. Considering the asymmetric spine overloads which frequently occur in sports training, meticulous posture assessment in young athletes seems well justified.

  16. Static and dynamic posture control in postlingual cochlear implanted patients: effects of dual-tasking, visual and auditory inputs suppression.

    Science.gov (United States)

    Bernard-Demanze, Laurence; Léonard, Jacques; Dumitrescu, Michel; Meller, Renaud; Magnan, Jacques; Lacour, Michel

    2013-01-01

    Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well

  17. Functional Neuroanatomy for Posture and Gait Control

    Directory of Open Access Journals (Sweden)

    Kaoru Takakusaki

    2017-01-01

    Full Text Available Here we argue functional neuroanatomy for posture- gait control. Multi-sensory information such as somatosensory, visual and vestibular sensation act on various areas of the brain so that adaptable posture- gait control can be achieved. Automatic process of gait, which is steady-state stepping movements associating with postural reflexes including headeye coordination accompanied by appropriate alignment of body segments and optimal level of postural muscle tone, is mediated by the descending pathways from the brainstem to the spinal cord. Particularly, reticulospinal pathways arising from the lateral part of the mesopontine tegmentum and spinal locomotor network contribute to this process. On the other hand, walking in unfamiliar circumstance requires cognitive process of postural control, which depends on knowledges of self-body, such as body schema and body motion in space. The cognitive information is produced at the temporoparietal association cortex, and is fundamental to sustention of vertical posture and construction of motor programs. The programs in the motor cortical areas run to execute anticipatory postural adjustment that is optimal for achievement of goal-directed movements. The basal ganglia and cerebellum may affect both the automatic and cognitive processes of posturegait control through reciprocal connections with the brainstem and cerebral cortex, respectively. Consequently, impairments in cognitive function by damages in the cerebral cortex, basal ganglia and cerebellum may disturb posture-gait control, resulting in falling.

  18. Neuromechanical tuning of nonlinear postural control dynamics

    Science.gov (United States)

    Ting, Lena H.; van Antwerp, Keith W.; Scrivens, Jevin E.; McKay, J. Lucas; Welch, Torrence D. J.; Bingham, Jeffrey T.; DeWeerth, Stephen P.

    2009-06-01

    Postural control may be an ideal physiological motor task for elucidating general questions about the organization, diversity, flexibility, and variability of biological motor behaviors using nonlinear dynamical analysis techniques. Rather than presenting "problems" to the nervous system, the redundancy of biological systems and variability in their behaviors may actually be exploited to allow for the flexible achievement of multiple and concurrent task-level goals associated with movement. Such variability may reflect the constant "tuning" of neuromechanical elements and their interactions for movement control. The problem faced by researchers is that there is no one-to-one mapping between the task goal and the coordination of the underlying elements. We review recent and ongoing research in postural control with the goal of identifying common mechanisms underlying variability in postural control, coordination of multiple postural strategies, and transitions between them. We present a delayed-feedback model used to characterize the variability observed in muscle coordination patterns during postural responses to perturbation. We emphasize the significance of delays in physiological postural systems, requiring the modulation and coordination of both the instantaneous, "passive" response to perturbations as well as the delayed, "active" responses to perturbations. The challenge for future research lies in understanding the mechanisms and principles underlying neuromechanical tuning of and transitions between the diversity of postural behaviors. Here we describe some of our recent and ongoing studies aimed at understanding variability in postural control using physical robotic systems, human experiments, dimensional analysis, and computational models that could be enhanced from a nonlinear dynamics approach.

  19. Compromising Postural Balance in the Elderly

    NARCIS (Netherlands)

    Swanenburg, Jaap; de Bruin, Eling D.; Uebelhart, Daniel; Mulder, Theo

    2009-01-01

    Background: Additional tasks that are assumed to disturb standing postural control can be divided in added motor or added cognitive tasks. It is unknown which type of task causes the most disturbances of postural control in elderly. Objective: The aim of this study was to determine whether the dual

  20. Postural Variables in Girls Practicing Volleyball

    Science.gov (United States)

    Grabara, Malgorzata; Hadzik, Andrzej

    2009-01-01

    Study aim: To assess body posture of young female volleyball players in relation to their untrained mates. Material and methods: A group of 42 volleyball players and another of 43 untrained girls, all aged 13-16 years were studied with respect to their body posture indices by using computer posturography. Spinal angles and curvatures were…

  1. The Relationship Between Postural and Movement Stability.

    Science.gov (United States)

    Feldman, Anatol G

    2016-01-01

    Postural stabilization is provided by stretch reflexes, intermuscular reflexes, and intrinsic muscle properties. Taken together, these posture-stabilizing mechanisms resist deflections from the posture at which balance of muscle and external forces is maintained. Empirical findings suggest that for each muscle, these mechanisms become functional at a specific, spatial threshold-the muscle length or respective joint angle at which motor units begin to be recruited. Empirical data suggest that spinal and supraspinal centers can shift the spatial thresholds for a group of muscles that stabilized the initial posture. As a consequence, the same stabilizing mechanisms, instead of resisting motion from the initial posture, drive the body to another stable posture. In other words by shifting spatial thresholds, the nervous system converts movement resisting to movement-producing mechanisms. It is illustrated that, contrary to conventional view, this control strategy allows the system to transfer body balance to produce locomotion and other actions without loosing stability at any point of them. It also helps orient posture and movement with the direction of gravity. It is concluded that postural and movement stability is provided by a common mechanism.

  2. Lung function and postural changes during pregnancy.

    Science.gov (United States)

    Nørregaard, O; Schultz, P; Ostergaard, A; Dahl, R

    1989-11-01

    The aim of this study was to determine the effects of postural changes on lung function in pregnant women during the first, second, third trimester and post partum. A significant decrease in FRC, PEF and FEV1 was observed as a result of the postural changes. Arterial oxygenation, MVV and DLCO remained largely the same.

  3. Effects of posture on postoperative pulmonary function

    DEFF Research Database (Denmark)

    Nielsen, K G; Holte, Kathrine; Kehlet, H

    2003-01-01

    BACKGROUND: Pulmonary morbidity is still a relevant complication to major surgery despite improvements in surgical technique and anaesthetic methods. Postoperative posture may be a pathogenic factor, but the effects of changes in postoperative posture on pulmonary function have not been reviewed...

  4. Correcting Poor Posture without Awareness or Willpower

    Science.gov (United States)

    Wernik, Uri

    2012-01-01

    In this article, a new technique for correcting poor posture is presented. Rather than intentionally increasing awareness or mobilizing willpower to correct posture, this approach offers a game using randomly drawn cards with easy daily assignments. A case using the technique is presented to emphasize the subjective experience of living with poor…

  5. INFLUENCE OF INJURY ON DYNAMIC POSTURAL CONTROL IN RUNNERS.

    Science.gov (United States)

    Meardon, Stacey; Klusendorf, Anna; Kernozek, Thomas

    2016-06-01

    Injury has been linked with altered postural control in active populations. The association between running injury and dynamic postural control has not been examined. The purpose of this study was to examine dynamic postural control in injured and uninjured runners using the Star Excursion Balance Test (SEBT), Time to Stabilization (TTS) of ground reaction forces following a single-leg landing, and postural stability indices reflecting the fluctuations in GRFs during single-leg landing and stabilization tasks (forward and lateral hop). It was hypothesized that dynamic postural control differences would exist between runners with a history of injury that interrupted training for ≥7 days (INJ) when compared to runners without injury (CON). Case-control study. Twenty-two INJ (14 F, 8 M; 23.7 ± 2.1 y; 22.3 ± 2.8 kg/m2; 29.5 ± 16.3 mi/wk) currently running > 50% pre-injury mileage without pain were compared with twenty-two matched CON (14F, 8M; 22.7 ± 1.2 y; 22.7 ± 2.7 kg/m2; 31.2 ± 19.6 mi/wk). INJ group was stratified by site of injury into two groups (Hip/Thigh/Knee and Lower Leg/Ankle/Foot) for secondary analysis. Leg length-normalized anterior, posterolateral, and posteromedial reach distances on the SEBT, medial/lateral and anterior/posterior ground reaction force TTS, directional postural stability indices, and a composite dynamic postural stability index (DPSI), were assessed using mixed model ANOVA (α=0.05) and effect sizes (d). No group X direction interaction or group differences were observed for the SEBT (p=0.51, 0.71) or TTS (p=0.83, 0.72) measures. A group X direction interaction was found for postural stability indices during the forward landing task (ppostural stability index (VPSI) (p=0.01 for both, d=0.80, 0.95) and DPSI (p=0.01, 0.02, d=0.75, 0.93) when compared to CON suggesting impaired balance control. A group X direction interaction was also found for postural stability indices during the lateral landing

  6. Reversibility of pulmonary function after inhaling salbutamol in different doses and body postures in asthmatic children.

    Science.gov (United States)

    Visser, R; Kelderman, S; de Jongh, F H C; van der Palen, J; Thio, B J

    2015-10-01

    Pulmonary medication is often delivered in the form of medical aerosols designed for inhalation. Recently, breath actuated inhalers (BAI's) gained popularity as they can be used without spacers. A major drawback of BAI's is the impaction in the upper airway. Stretching the upper airway by a forward leaning body posture with the neck extended ("sniffing position") during inhalation may reduce upper airway impaction and improve pulmonary deposition. Aim of this study was to investigate the reversibility of lung function with different doses salbutamol inhaled with a BAI in the forward leaning posture compared to the standard posture in asthmatic children. 22 clinically stable asthmatic children, 5-14 years old, performed four reversibility measurements. Children inhaled 200 μg or 400 μg salbutamol with a BAI in the standard or in the forward leaning posture with the neck extended in a randomized single-blinded cross-over design. Reversibility of lung function after inhaling salbutamol in the forward leaning posture was not significantly different compared to inhalation in the standard posture. Mean FEV1 reversibility was significantly greater after inhaling 400 μg salbutamol compared to 200 μg salbutamol in the standard posture (9.4% ± 9.5% versus 4.5% ± 7.5%, difference 4.9% (95CI 0.9; 9.0%); p = 0.021). In clinically stable asthmatic children, inhalation of salbutamol with a BAI in a forward leaning posture does not increase reversibility of lung function. Inhalation of 400 μg compared to 200 μg salbutamol with a BAI does improve reversibility. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Fatiguing exercise intensity influences the relationship between parameters reflecting neuromuscular function and postural control variables.

    Directory of Open Access Journals (Sweden)

    Sébastien Boyas

    Full Text Available The purpose of this study was to investigate the influence of fatiguing exercise intensity on the nature and extent of fatigue-induced changes in neuromuscular function and postural stability in quiet standing. We also explored the contribution of selected neuromuscular mechanisms involved in force production to postural stability impairment observed following fatigue using an approach based on multivariate regressions. Eighteen young subjects performed 30-s postural trials on one leg with their eyes closed. Postural trials were performed before and after fatiguing exercises of different intensities: 25, 50 and 75% of maximal isometric plantarflexor torque. Fatiguing exercises consisted of sustaining a plantarflexor isometric contraction at the target intensity until task failure. Maximal isometric plantarflexor torque, electromyographic activity of plantarflexor and dorsiflexor muscles, activation level (twitch interpolation technique and twitch contractile properties of plantarflexors were used to characterize neuromuscular function. The 25% exercise was associated with greater central fatigue whereas the 50 and 75% exercises involved mostly peripheral fatigue. However, all fatiguing exercises induced similar alterations in postural stability, which was unexpected considering previous literature. Stepwise multiple regression analyses showed that fatigue-related changes in selected parameters related to neuromuscular function could explain more than half (0.51≤R(2≤0.82 of the changes in postural variables for the 25% exercise. On the other hand, regression models were less predictive (0.17≤R(2≤0.73 for the 50 and 75% exercises. This study suggests that fatiguing exercise intensity does not influence the extent of postural stability impairment, but does influence the type of fatigue induced and the neuromuscular function predictors explaining changes in postural variables.

  8. The Role of Neuromuscular Changes in Aging and Knee Osteoarthritis on Dynamic Postural Control

    Science.gov (United States)

    Takacs, Judit; Carpenter, Mark G.; Garland, S. Jayne; Hunt, Michael A.

    2013-01-01

    Knee osteoarthritis (OA) is a chronic joint condition, with 30% of those over the age of 75 exhibiting severe radiographic disease. Nearly 50% of those with knee OA have experienced a fall in the past year. Falls are a considerable public health concern, with a high risk of serious injury and a significant socioeconomic impact. The ability to defend against a fall relies on adequate dynamic postural control, and alterations in dynamic postural control are seen with normal aging. Neuromuscular changes associated with aging may be responsible for some of these alterations in dynamic postural control. Even greater neuromuscular deficits, which may impact dynamic postural control and the ability to defend against a fall, are seen in people with knee OA. There is little evidence to date on how knee OA affects the ability to respond to and defend against falls and the neuromuscular changes that contribute to balance deficits. As a result, this review will: summarize the key characteristics of postural responses to an external perturbation, highlight the changes in dynamic postural control seen with normal aging, review the neuromuscular changes associated with aging that have known and possible effects on dynamic postural control, and summarize the neuromuscular changes and balance problems in knee OA. Future research to better understand the role of neuromuscular changes in knee OA and their effect on dynamic postural control will be suggested. Such an understanding is critical to the successful creation and implementation of fall prevention and treatment programs, in order to reduce the excessive risk of falling in knee OA. PMID:23696951

  9. An investigation of rugby scrimmaging posture and individual maximum pushing force.

    Science.gov (United States)

    Wu, Wen-Lan; Chang, Jyh-Jong; Wu, Jia-Hroung; Guo, Lan-Yuen

    2007-02-01

    Although rugby is a popular contact sport and the isokinetic muscle torque assessment has recently found widespread application in the field of sports medicine, little research has examined the factors associated with the performance of game-specific skills directly by using the isokinetic-type rugby scrimmaging machine. This study is designed to (a) measure and observe the differences in the maximum individual pushing forward force produced by scrimmaging in different body postures (3 body heights x 2 foot positions) with a self-developed rugby scrimmaging machine and (b) observe the variations in hip, knee, and ankle angles at different body postures and explore the relationship between these angle values and the individual maximum pushing force. Ten national rugby players were invited to participate in the examination. The experimental equipment included a self-developed rugby scrimmaging machine and a 3-dimensional motion analysis system. Our results showed that the foot positions (parallel and nonparallel foot positions) do not affect the maximum pushing force; however, the maximum pushing force was significantly lower in posture I (36% body height) than in posture II (38%) and posture III (40%). The maximum forward force in posture III (40% body height) was also slightly greater than for the scrum in posture II (38% body height). In addition, it was determined that hip, knee, and ankle angles under parallel feet positioning are factors that are closely negatively related in terms of affecting maximum pushing force in scrimmaging. In cross-feet postures, there was a positive correlation between individual forward force and hip angle of the rear leg. From our results, we can conclude that if the player stands in an appropriate starting position at the early stage of scrimmaging, it will benefit the forward force production.

  10. Aging worsens the effects of sleep deprivation on postural control.

    Science.gov (United States)

    Robillard, Rébecca; Prince, François; Filipini, Daniel; Carrier, Julie

    2011-01-01

    Falls increase with age and cause significant injuries in the elderly. This study aimed to determine whether age modulates the interactions between sleep deprivation and postural control and to evaluate how attention influences these interactions in the elderly. Fifteen young (24±2.7 y.o.) and 15 older adults (64±3.2 y.o.) stood still on a force plate after a night of sleep and after total sleep deprivation. Center of pressure range and velocity were measured with eyes open and with eyes closed while participants performed an interference task, a control task, and no cognitive task. Sleep deprivation increased the antero-posterior range of center of pressure in both age groups and center of pressure speed in older participants only. In elderly participants, the destabilizing effects of sleep deprivation were more pronounced with eyes closed. The interference task did not alter postural control beyond the destabilization induced by sleep loss in older subjects. It was concluded that sleep loss has greater destabilizing effects on postural control in older than in younger participants, and may therefore increase the risk of falls in the elderly.

  11. Aging Worsens the Effects of Sleep Deprivation on Postural Control

    Science.gov (United States)

    Robillard, Rébecca; Prince, François; Filipini, Daniel; Carrier, Julie

    2011-01-01

    Falls increase with age and cause significant injuries in the elderly. This study aimed to determine whether age modulates the interactions between sleep deprivation and postural control and to evaluate how attention influences these interactions in the elderly. Fifteen young (24±2.7 y.o.) and 15 older adults (64±3.2 y.o.) stood still on a force plate after a night of sleep and after total sleep deprivation. Center of pressure range and velocity were measured with eyes open and with eyes closed while participants performed an interference task, a control task, and no cognitive task. Sleep deprivation increased the antero-posterior range of center of pressure in both age groups and center of pressure speed in older participants only. In elderly participants, the destabilizing effects of sleep deprivation were more pronounced with eyes closed. The interference task did not alter postural control beyond the destabilization induced by sleep loss in older subjects. It was concluded that sleep loss has greater destabilizing effects on postural control in older than in younger participants, and may therefore increase the risk of falls in the elderly. PMID:22163330

  12. Dual task and postural control in Alzheimer's and Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Larissa Pires de Andrade

    2014-03-01

    Full Text Available Patients with neurodegenerative diseases are required to use cognitive resources while maintaining postural control. The aim of this study was to investigate the effects of a frontal cognitive task on postural control in patients with Alzheimer, Parkinson and controls. Thirty-eight participants were instructed to stand upright on a force platform in two experimental conditions: single and dual task. Participants with Parkinson's disease presented an increase in the coefficient of variation greater than 100% in the dual task as compared to the single task for center of pressure (COP area and COP path. In addition, patients with Parkinson's and Alzheimer's disease had a higher number of errors during the execution of the cognitive task when compared to the group of elderly without neurodegenerative diseases. The motor cortex, which is engaged in postural control, does not seem to compete with frontal brain regions in the performance of the cognitive task. However, patients with Parkinson's and Alzheimer's disease presented worsened performance in cognitive task.

  13. Benefit of bi-ocular visual stimulation for postural control in children with strabismus.

    Science.gov (United States)

    Gaertner, Chrystal; Creux, Charlotte; Espinasse-Berrod, Marie-Andrée; Orssaud, Christophe; Dufier, Jean-Louis; Kapoula, Zoï

    2013-01-01

    Vision is important for postural control as is shown by the Romberg quotient (RQ): with eyes closed, postural instability increases relative to eyes open (RQ = 2). Yet while fixating at far distance, postural stability is similar with eyes open and eyes closed (RQ = 1). Postural stability can be better with both eyes viewing than one eye, but such effect is not consistent among healthy subjects. The first goal of the study is to test the RQ as a function of distance for children with convergent versus divergent strabismus. The second goal is to test whether vision from two eyes relative to vision from one eye provides better postural stability. Thirteen children with divergent strabismus and eleven with convergent strabismus participated in this study. Posturtography was done with the Techno concept device. Experiment 1, four conditions: fixation at 40 cm and at 200 cm both with eyes open and eyes covered (evaluation of RQ). Experiment 2, six conditions: fixation at 40 cm and at 200 cm, with both eyes viewing or under monocular vision (dominant and non-dominant eye). For convergent strabismus, the groups mean value of RQ was 1.3 at near and 0.94 at far distance; for divergent, it was 1.06 at near and 1.68 at far. For all children, the surface of body sway was significantly smaller under both eyes viewing than monocular viewing (either eye). Increased RQ value at near for convergent and at far for divergent strabismus is attributed to the influence of the default strabismus angle and to better use of ocular motor signals. Vision with the two eyes improves postural control for both viewing distances and for both types of strabismus. Such benefit can be due to complementary mechanisms: larger visual field, better quality of fixation and vergence angle due to the use of visual inputs from both eyes.

  14. Benefit of bi-ocular visual stimulation for postural control in children with strabismus.

    Directory of Open Access Journals (Sweden)

    Chrystal Gaertner

    Full Text Available Vision is important for postural control as is shown by the Romberg quotient (RQ: with eyes closed, postural instability increases relative to eyes open (RQ = 2. Yet while fixating at far distance, postural stability is similar with eyes open and eyes closed (RQ = 1. Postural stability can be better with both eyes viewing than one eye, but such effect is not consistent among healthy subjects. The first goal of the study is to test the RQ as a function of distance for children with convergent versus divergent strabismus. The second goal is to test whether vision from two eyes relative to vision from one eye provides better postural stability. Thirteen children with divergent strabismus and eleven with convergent strabismus participated in this study. Posturtography was done with the Techno concept device. Experiment 1, four conditions: fixation at 40 cm and at 200 cm both with eyes open and eyes covered (evaluation of RQ. Experiment 2, six conditions: fixation at 40 cm and at 200 cm, with both eyes viewing or under monocular vision (dominant and non-dominant eye. For convergent strabismus, the groups mean value of RQ was 1.3 at near and 0.94 at far distance; for divergent, it was 1.06 at near and 1.68 at far. For all children, the surface of body sway was significantly smaller under both eyes viewing than monocular viewing (either eye. Increased RQ value at near for convergent and at far for divergent strabismus is attributed to the influence of the default strabismus angle and to better use of ocular motor signals. Vision with the two eyes improves postural control for both viewing distances and for both types of strabismus. Such benefit can be due to complementary mechanisms: larger visual field, better quality of fixation and vergence angle due to the use of visual inputs from both eyes.

  15. Postural control during the Stroop test in dyslexic and non dyslexic teenagers.

    Directory of Open Access Journals (Sweden)

    Zoï Kapoula

    Full Text Available Postural control in quiet stance although simple still requires some cognitive resources; dual cognitive tasks influence further postural control. The present study examines whether or not dyslexic teenagers experience postural instability when performing a Stroop dual task for which their performances are known to be poor. Fifteen dyslexics and twelve non-dyslexics (14 to 17 years old were recruited from the same school. They were asked to perform three tasks: (1 fixate a target, (2 perform an interference Stroop test (naming the colour or the word rather than reading the word, (3 performing flexibility Stroop task: the subject performed the interference task as in (2 except when the word was in a box, in which case he had to read the word. Postural performances were measured with a force platform. The results showed a main task effect on the variance of speed of body sway only: such variance was higher in the flexibility task than for the other two tasks. No group effect was found for any of the parameters of posture (surface, mediolateral and anteroposterior sway, variance of speed. Further wavelet analysis in the time-frequency domain revealed an increase in the spectral power of the medium frequency range believed to be related to cerebellum control; an accompanying increase in the cancellation time of the high frequency band related to reflexive loops occurred for non-dyslexics only. These effects occurred for the flexibility task and could be due to its high cognitive difficulty. Dyslexics displayed shorter cancellation time for the medium frequency band for all tasks, suggesting less efficient cerebellar control, perhaps of eye fixation and attention influencing body sway. We conclude that there is no evidence for a primary posture deficit in 15 year old teenagers who come from the general population and who were recruited in schools.

  16. Postural Coordination during Socio-motor Improvisation.

    Science.gov (United States)

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

    2016-01-01

    Human interaction often relies on socio-motor improvisation. Creating unprepared movements during social interaction is not a random process but relies on rules of synchronization. These situations do not only involve people to be coordinated, but also require the adjustment of their posture in order to maintain balance and support movements. The present study investigated posture in such a context. More precisely, we first evaluated the impact of amplitude and complexity of arm movements on posture in solo situation. Then, we assessed the impact of interpersonal coordination on posture using the mirror game in which dyads performed improvised and synchronized movements (i.e., duo situation). Posture was measured through ankle-hip coordination in medio-lateral and antero-posterior directions (ML and AP respectively). Our results revealed the spontaneous emergence of in-phase pattern in ML direction and antiphase pattern in AP direction for solo and duo situations. These two patterns respectively refer to the simultaneous flexion/extension of the ankles and the hips in the same or opposite direction. It suggests different functional roles of postural coordination patterns in each direction, with in-phase supporting task performance in ML (dynamical stability) and antiphase supporting postural control in AP (mechanical stability). Although amplitude of movement did not influence posture, movement complexity disturbed postural stability in both directions. Conversely, interpersonal coordination promoted postural stability in ML but not in AP direction. These results are discussed in terms of the difference in coupling strength between ankle-hip coordination and interpersonal coordination.

  17. Postural coordination during socio-motor improvisation

    Directory of Open Access Journals (Sweden)

    Mathieu Gueugnon

    2016-08-01

    Full Text Available Human interaction often relies on socio-motor improvisation. Creating unprepared movements during social interaction is not a random process but relies on rules of synchronization. These situations do not only involve people to be coordinated, but also require the adjustment of their posture in order to maintain balance and support movements. The present study investigated posture in such a context. More precisely, we first evaluated the impact of amplitude and complexity of arm movements on posture in solo situation. Then, we assessed the impact of interpersonal coordination on posture using the mirror game in which dyads performed improvised and synchronized movements (i.e., duo situation. Posture was measured through ankle-hip coordination in medio-lateral and antero-posterior directions (ML and AP respectively. Our results revealed the spontaneous emergence of in-phase pattern in ML direction and anti-phase pattern in AP direction for solo and duo situations. These two patterns respectively refer to the simultaneous flexion/extension of the ankles and the hips in the same or opposite direction. It suggests different functional roles of postural coordination patterns in each direction, with in-phase supporting task performance in ML (dynamical stability and antiphase supporting postural control in AP (mechanical stability. Although amplitude of movement did not influence posture, movement complexity disturbed postural stability in both directions. Conversely, interpersonal coordination promoted postural stability in ML but not in AP direction. These results are discussed in terms of the difference in coupling strength between ankle-hip coordination and interpersonal coordination.

  18. Body surface posture evaluation: construction, validation and protocol of the SPGAP system (Posture evaluation rotating platform system).

    Science.gov (United States)

    Schwertner, Debora Soccal; Oliveira, Raul; Mazo, Giovana Zarpellon; Gioda, Fabiane Rosa; Kelber, Christian Roberto; Swarowsky, Alessandra

    2016-05-04

    Several posture evaluation devices have been used to detect deviations of the vertebral column. However it has been observed that the instruments present measurement errors related to the equipment, environment or measurement protocol. This study aimed to build, validate, analyze the reliability and describe a measurement protocol for the use of the Posture Evaluation Rotating Platform System (SPGAP, Brazilian abbreviation). The posture evaluation system comprises a Posture Evaluation Rotating Platform, video camera, calibration support and measurement software. Two pilot studies were carried out with 102 elderly individuals (average age 69 years old, SD = ±7.3) to establish a protocol for SPGAP, controlling the measurement errors related to the environment, equipment and the person under evaluation. Content validation was completed with input from judges with expertise in posture measurement. The variation coefficient method was used to validate the measurement by the instrument of an object with known dimensions. Finally, reliability was established using repeated measurements of the known object. Expert content judges gave the system excellent ratings for content validity (mean 9.4 out of 10; SD 1.13). The measurement of an object with known dimensions indicated excellent validity (all measurement errors reality. To verify the images of objects with known dimensions the values for the width and height were, respectively, CV 0.88 (width) and 2.33 (height), SD 0.22 (width) and 0.35 (height), minimum and maximum values 24.83-25.2 (width) and 14.56 - 15.75 (height). In the analysis of different images (similar) of an individual, greater discrepancies were observed in the values found. The cervical index, for example, presented minimum and maximum values of 15.38 and 37.5, a coefficient of variation of 0.29 and a standard deviation of 6.78. The SPGAP was shown to be a valid and reliable instrument for the quantitative analysis of body posture with applicability and

  19. Postural control deficits in people with fibromyalgia: a pilot study

    Science.gov (United States)

    2011-01-01

    Introduction Postural instability and falls are increasingly recognized problems in patients with fibromyalgia (FM). The purpose of this study was to determine whether FM patients, compared to age-matched healthy controls (HCs), have differences in dynamic posturography, including sensory, motor, and limits of stability. We further sought to determine whether postural instability is associated with strength, proprioception and lower-extremity myofascial trigger points (MTPs); FM symptoms and physical function; dyscognition; balance confidence; and medication use. Last, we evaluated self-reported of falls over the past six months. Methods In this cross-sectional study, we compared middle-aged FM patients and age-matched HCs who underwent computerized dynamic posturography testing and completed the Fibromyalgia Impact Questionnaire-Revised (FIQR) and balance and fall questionnaires. All subjects underwent a neurological and musculoskeletal examination. Descriptive statistics were used to characterize the sample and explore the relationships between variables. The relationships between subjective, clinical and objective variables were evaluated by correlation and regression analyses. Results Twenty-five FM patients and twenty-seven HCs (combined mean age ± standard deviation (SD): 48.6 ± 9.7 years) completed testing. FM patients scored statistically lower on composite sensory organization tests (primary outcome; P < 0.010), as well as with regard to vestibular, visual and somatosensory ratio scores on dynamic posturography. Balance confidence was significantly different between groups, with FM patients reporting less confidence than HCs (mean ± SD: 81.24 ± 19.52 vs. 98.52 ± 2.45; P < 0.001). Interestingly, 76% to 84% of FM patients had gastrocnemius and/or anterior tibialis MTPs. Postural stability was best predicted by dyscognition, FIQR score and body mass index. Regarding falls, 3 (11%) of 27 HCs had fallen only once during the past 6 months, whereas 18 (72

  20. An active balance board system with real-time control of stiffness and time-delay to assess mechanisms of postural stability.

    Science.gov (United States)

    Cruise, Denise R; Chagdes, James R; Liddy, Joshua J; Rietdyk, Shirley; Haddad, Jeffrey M; Zelaznik, Howard N; Raman, Arvind

    2017-07-26

    Increased time-delay in the neuromuscular system caused by neurological disorders, concussions, or advancing age is an important factor contributing to balance loss (Chagdes et al., 2013, 2016a,b). We present the design and fabrication of an active balance board system that allows for a systematic study of stiffness and time-delay induced instabilities in standing posture. Although current commercial balance boards allow for variable stiffness, they do not allow for manipulation of time-delay. Having two controllable parameters can more accurately determine the cause of balance deficiencies, and allows us to induce instabilities even in healthy populations. An inverted pendulum model of human posture on such an active balance board predicts that reduced board rotational stiffness destabilizes upright posture through board tipping, and limit cycle oscillations about the upright position emerge as feedback time-delay is increased. We validate these two mechanisms of instability on the designed balance board, showing that rotational stiffness and board time-delay induced the predicted postural instabilities in healthy, young adults. Although current commercial balance boards utilize control of rotational stiffness, real-time control of both stiffness and time-delay on an active balance board is a novel and innovative manipulation to reveal balance deficiencies and potentially improve individualized balance training by targeting multiple dimensions contributing to standing balance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Physiological Mechanisms Mediating the Coupling between Heart Period and Arterial Pressure in Response to Postural Changes in Humans

    OpenAIRE

    Silvani, Alessandro; Calandra-Buonaura, Giovanna; Johnson, Blair D.; van Helmond, Noud; Barletta, Giorgio; Cecere, Anna G.; Joyner, Michael J.; Cortelli, Pietro

    2017-01-01

    The upright posture strengthens the coupling between heart period (HP) and systolic arterial pressure (SAP) consistently with a greater contribution of the arterial baroreflex to cardiac control, while paradoxically decreasing cardiac baroreflex sensitivity (cBRS). To investigate the physiological mechanisms that mediate the coupling between HP and SAP in response to different postures, we analyzed the cross-correlation functions between low-frequency HP and SAP fluctuations and estimated cBR...

  2. Postural control is altered in patients with ankylosing spondylitis.

    Science.gov (United States)

    Vergara, Martin E; O'Shea, Finbar D; Inman, Robert D; Gage, William H

    2012-05-01

    Ankylosing spondylitis is a chronic inflammatory disorder that can lead to increased axial and peripheral joint stiffness, impairing joint mobility. Impaired axial mobility due to vertebral ankylosis may result in changes in standing postural control. Little research has addressed changes in standing postural control in the ankylosing spondylitis population, nor how these issues might affect clinical understanding and treatment. Sixteen ankylosing spondylitis patients, and 17 healthy controls participated. Each individual completed two 120-second quiet standing trials with eyes open and eyes closed, while standing upon two force platforms. Net center of pressure displacement and mean power frequency in the frontal and sagittal planes were calculated. A Spearman's rank correlation analysis was performed between net center of pressure measures and several clinical measures of disease activity. Frontal plane net center of pressure displacement and frequency content, and sagittal plane net center of pressure displacement were significantly greater within the ankylosing spondylitis patient group. Ankylosing spondylitis patients demonstrated a significant increase in frontal plane net center of pressure displacement in the eyes-closed condition. Net center of pressure displacement and frequency were significantly correlated to the Bath Ankylosing Spondylitis Functional Index, and individual components of the Bath Ankylosing Spondylitis Metrology Index. Quiet standing postural control was altered particularly so in the frontal plane in patients with ankylosing spondylitis, which may be associated with increased fall risk. Posturographic measures of postural control may serve as valuable clinical tools for the monitoring of disease progression and disease status in ankylosing spondylitis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Affective instability as a clinical feature of avoidant personality disorder.

    Science.gov (United States)

    Snir, Avigal; Bar-Kalifa, Eran; Berenson, Kathy R; Downey, Geraldine; Rafaeli, Eshkol

    2017-10-01

    The current study's main goal was to examine whether affective instability is elevated among individuals suffering from avoidant personality disorder (APD) by comparing it to the affective instability found among individuals suffering from borderline personality disorder (BPD) as well that found among healthy controls. Adults (N = 152, aged 18-65 years) with BPD, APD, or no psychopathology participated in a 3-week computerized diary study. We examined temporal instability in negative affect using experience-sampling methods. Both within and between days, individuals with APD showed greater affective instability compared to the healthy control individuals, although less affective instability compared to individuals with BPD. The findings are in line with affective instability (or emotional lability) as a key dimension relevant across personality disorders. Additionally, they emphasize the need for research and clinical attention to affective characteristics (alongside the more readily recognized interpersonal characteristics) of APD. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  4. Tearing instabilities in turbulence

    International Nuclear Information System (INIS)

    Ishizawa, A.; Nakajima, N.

    2009-01-01

    Full text: Effects of micro-turbulence on tearing instabilities are investigated by numerically solving a reduced set of two-fluid equations. Micro-turbulence excites both large-scale and small-scale Fourier modes through energy transfer due to nonlinear mode coupling. The energy transfer to large scale mode does not directly excite tearing instability but it gives an initiation of tearing instability. When tearing instability starts to grow, the excited small scale mode plays an important role. The mixing of magnetic flux by micro-turbulence is the dominant factor of non-ideal MHD effect at the resonant surface and it gives rise to magnetic reconnection which causes tearing instability. Tearing instabilities were investigated against static equilibrium or flowing equilibrium so far. On the other hand, the recent progress of computer power allows us to investigate interactions between turbulence and coherent modes such as tearing instabilities in magnetically confined plasmas by means of direct numerical simulations. In order to investigate effects of turbulence on tearing instabilities we consider a situation that tearing mode is destabilized in a quasi-equilibrium including micro-turbulence. We choose an initial equilibrium that is unstable against kinetic ballooning modes and tearing instabilities. Tearing instabilities are current driven modes and thus they are unstable for large scale Fourier modes. On the other hand kinetic ballooning modes are unstable for poloidal Fourier modes that are characterized by ion Larmor radius. The energy of kinetic ballooning modes spreads over wave number space through nonlinear Fourier mode coupling. We present that micro-turbulence affects tearing instabilities in two different ways by three-dimensional numerical simulation of a reduced set of two-fluid equations. One is caused by energy transfer to large scale modes, the other is caused by energy transfer to small scale modes. The former is the excitation of initial

  5. The Effect of Spinal Tap Test on Different Sensory Modalities of Postural Stability in Idiopathic Normal Pressure Hydrocephalus

    Directory of Open Access Journals (Sweden)

    Katrin Abram

    2016-09-01

    Full Text Available Background/Aims: Postural instability in patients with normal pressure hydrocephalus (NPH is a most crucial symptom leading to falls with secondary complications. The aim of the current study was to evaluate the therapeutic effect of spinal tap on postural stability in these patients. Methods: Seventeen patients with clinical symptoms of NPH were examined using gait scale, computerized dynamic posturography (CDP, and neuropsychological assessment. Examinations were done before and after spinal tap test. Results: The gait score showed a significant improvement 24 h after spinal tap test in all subtests and in the sum score (p Conclusion: Postural stability in NPH is predominantly affected by deficient vestibular functions, which did not improve after spinal tap test. Conditions which improved best were mainly independent from visual control and are based on proprioceptive functions.

  6. Analysis of postural sway in patients with normal pressure hydrocephalus: effects of shunt implantation

    Directory of Open Access Journals (Sweden)

    Czerwosz L

    2009-12-01

    Full Text Available Abstract Poor postural balance is one of the major risk factors for falling in normal pressure hydrocephalus (NPH. Postural instability in the clinic is commonly assessed based upon force platform posturography. In this study we focused on the identification of changes in sway characteristics while standing quiet in patients with NPH before and after shunt implantation. Postural sway area and sway radius were analyzed in a group of 9 patients and 46 controls of both genders. Subject's spontaneous sway was recorded while standing quiet on a force platform for 30-60 s, with eyes open and then closed. Both analyzed sway descriptors identified between-group differences and also an effect of shunt implantation in the NPH group. Sway radius and sway area in patients exhibited very high values compared with those in the control group. Importantly, the effect of eyesight in patients was not observed before shunt implantation and reappeared after the surgical treatment. The study documents that static force platform posturography may be a reliable measure of postural control improvement due to shunt surgery.

  7. Effect of cognitive and motor tasks on postural stability in Parkinson's disease: a posturographic study.

    Science.gov (United States)

    Marchese, Roberta; Bove, Marco; Abbruzzese, Giovanni

    2003-06-01

    To analyse the effect of concomitant cognitive or motor task performance on balance control in Parkinson's disease (PD), we performed a posturographic study in 24 PD patients and in 20 sex- and age-matched control subjects. Postural sway was measured with eyes open (EO) and eyes closed (EC) during quiet stance and during performance of calculation or motor sequence of thumb opposition to the other fingers. No difference of centre of foot pressure (COP) parameters was observed during quiet standing (either EO or EC) between patients and controls, but visual deprivation induced in both groups a worsening of postural stability. COP area was significantly increased in PD patients during dual task performance, whereas no difference of COP path and x-y axes was observed. The effects induced by the performance of cognitive or motor task were significantly more evident in PD patients with clinical evidence of postural instability (presence of prior falls in the history). This study demonstrates that dual task interference on postural control can be observed in PD patients during performance of cognitive as well as motor tasks. The balance deterioration during dual task performance was significantly enhanced in patients with history of prior falls. These findings have some implications for the strategies to be used in reducing the risk of fall in PD. Copyright 2003 Movement Disorder Society

  8. Effects of Spaceflight and Hindlimb Suspension on the Posture and Gait of Rats

    Science.gov (United States)

    Fox, R. A.; Corcoran, M.; Daunton, N. G.; Morey-Holton, E.

    1994-01-01

    Instability of posture and gait in astronauts following spaceflight (SF) is thought to result from muscle atrophy and from changes in sensory-motor integration in the CNS (central nervous system) that occur during adaptation to microgravity (micro-G). Individuals are thought to have developed, during SF, adaptive changes for the processing of proprioceptive, vestibular and visual sensory inputs with reduced weighting of gravity-based signals and increased weighting of visual and tactile cues. This sensory-motor rearrangement in the CNS apparently occurs to optimize neuromuscular system function for effective movement and postural control in micro-G. However, these adaptive changes are inappropriate for the 1 g environment and lead to disruptions in posture and gait on return to Earth. Few reports are available on the effects of SF on the motor behavior of animals. Rats studied following 18.5 - 19.5 days of SF in the COSMOS program were described as being ..'inert, apathetic, slow'.. and generally unstable. The hindlimbs of these rats were ..'thrust out from the body with fingers pulled apart and the shin unnaturally pronated'. On the 6th postflight day motor behavior was described as similar to that observed in preflight observations. Improved understanding of the mechanisms leading to these changes can be obtained in animal models through detailed analysis of neural and molecular mechanisms related to gait. To begin this process the posture and gait of rats were examined following exposure to either SF or hindlimb suspension (HLS), and during recovery from these conditions.

  9. Overview of the management of postural tachycardia syndrome in pregnant patients.

    Science.gov (United States)

    Ruzieh, Mohammed; Grubb, Blair P

    2018-02-16

    Postural tachycardia syndrome (POTS) is a chronic condition characterized by symptoms of orthostatic intolerance. Pregnancy can cause different physiological changes in cardiovascular parameters, that could have greater impact on POTS patients. In this review, we discuss the management of POTS in the pregnant and obstetric settings. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. An investigation into essential aspects of posture in primary school ...

    African Journals Online (AJOL)

    Postures of the subjects were analysed by means of photographic images using the pro forma of Barlow (1956, 1990). The majority of the executives had malposture with 2.3%, 23.3%, 58.1% and 16.3% and 6.3% of the subjects being categorised with slight postural defects, severe postural defects, very severe postural ...

  11. Relativistic gravitational instabilities

    International Nuclear Information System (INIS)

    Schutz, B.F.

    1987-01-01

    The purpose of these lectures is to review and explain what is known about the stability of relativistic stars and black holes, with particular emphases on two instabilities which are due entirely to relativistic effects. The first of these is the post-Newtonian pulsational instability discovered independently by Chandrasekhar (1964) and Fowler (1964). This effectively ruled out the then-popular supermassive star model for quasars, and it sets a limit to the central density of white dwarfs. The second instability was also discovered by Chandrasekhar (1970): the gravitational wave induced instability. This sets an upper bound on the rotation rate of neutron stars, which is near that of the millisecond pulsar PSR 1937+214, and which is beginning to constrain the equation of state of neutron matter. 111 references, 5 figures

  12. Character of decay instability

    International Nuclear Information System (INIS)

    Polovin, R.V.; Demutskii, V.P.

    1981-01-01

    If the initial wave is unstable in the upper half plane Im ω>0 and there are no branch points of the quasiwave number, or if waves traveling in the same direction coalesce at a branch point, the instability is convective. On the other hand, if a branch point k(ω) does exist in the upper half-plane Im ω>0, and not all the waves that merge at this point travel in the same direction, the instability is absolute. A Green's function that describes the evolution of the perturbations of the initial wave in space and in time is constructed. The growth rates of the decay instability of the harmonics are determined. The produced waves are richer in harmonics than the initial waves. It is shown that the decay instability of an Alfven wave is absolute

  13. Spondylolisthesis and Posterior Instability

    International Nuclear Information System (INIS)

    Niggemann, P.; Beyer, H.K.; Frey, H.; Grosskurth, D.; Simons, P.; Kuchta, J.

    2009-01-01

    We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI

  14. Spondylolisthesis and Posterior Instability

    Energy Technology Data Exchange (ETDEWEB)

    Niggemann, P.; Beyer, H.K.; Frey, H.; Grosskurth, D. (Privatpraxis fuer Upright MRT, Koeln (Germany)); Simons, P.; Kuchta, J. (Media Park Klinik, Koeln (Germany))

    2009-04-15

    We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI.

  15. Streaming gravity mode instability

    International Nuclear Information System (INIS)

    Wang Shui.

    1989-05-01

    In this paper, we study the stability of a current sheet with a sheared flow in a gravitational field which is perpendicular to the magnetic field and plasma flow. This mixing mode caused by a combined role of the sheared flow and gravity is named the streaming gravity mode instability. The conditions of this mode instability are discussed for an ideal four-layer model in the incompressible limit. (author). 5 refs

  16. Genomic instability and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Little, John B [Harvard School of Public Health, Boston, MA 02115 (United States)

    2003-06-01

    Genomic instability is a hallmark of cancer cells, and is thought to be involved in the process of carcinogenesis. Indeed, a number of rare genetic disorders associated with a predisposition to cancer are characterised by genomic instability occurring in somatic cells. Of particular interest is the observation that transmissible instability can be induced in somatic cells from normal individuals by exposure to ionising radiation, leading to a persistent enhancement in the rate at which mutations and chromosomal aberrations arise in the progeny of the irradiated cells after many generations of replication. If such induced instability is involved in radiation carcinogenesis, it would imply that the initial carcinogenic event may not be a rare mutation occurring in a specific gene or set of genes. Rather, radiation may induce a process of instability in many cells in a population, enhancing the rate at which the multiple gene mutations necessary for the development of cancer may arise in a given cell lineage. Furthermore, radiation could act at any stage in the development of cancer by facilitating the accumulation of the remaining genetic events required to produce a fully malignant tumour. The experimental evidence for such induced instability is reviewed. (review)

  17. Genomic instability and radiation

    International Nuclear Information System (INIS)

    Little, John B

    2003-01-01

    Genomic instability is a hallmark of cancer cells, and is thought to be involved in the process of carcinogenesis. Indeed, a number of rare genetic disorders associated with a predisposition to cancer are characterised by genomic instability occurring in somatic cells. Of particular interest is the observation that transmissible instability can be induced in somatic cells from normal individuals by exposure to ionising radiation, leading to a persistent enhancement in the rate at which mutations and chromosomal aberrations arise in the progeny of the irradiated cells after many generations of replication. If such induced instability is involved in radiation carcinogenesis, it would imply that the initial carcinogenic event may not be a rare mutation occurring in a specific gene or set of genes. Rather, radiation may induce a process of instability in many cells in a population, enhancing the rate at which the multiple gene mutations necessary for the development of cancer may arise in a given cell lineage. Furthermore, radiation could act at any stage in the development of cancer by facilitating the accumulation of the remaining genetic events required to produce a fully malignant tumour. The experimental evidence for such induced instability is reviewed. (review)

  18. Effect of the Oculus Rift head mounted display on postural stability

    DEFF Research Database (Denmark)

    Epure, Paula; Gheorghe, Cristina; Nissen, Thomas

    2014-01-01

    board controlling a skiing game. Two tests were conducted: full-vision versus blindfolded and HMD versus monitor display. Results were that five of the six balance-impaired adults and six of the eight non-balance-impaired adults showed higher degree of postural stability while using a monitor display......This study explored how a HMD-experienced virtual environment influences physical balance of six balance-impaired adults 59-69 years-of-age, when compared to a control group of eight non-balance-impaired adults, 18-28 years-of-age. The setup included a Microsoft Kinect and a self-created balance....... Conclusions are that HMD, used in this context, leads to postural instability....

  19. 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

  20. The effect of moderate running on foot posture index and plantar pressure distribution in male recreational runners.

    Science.gov (United States)

    Escamilla-Martínez, Elena; Martínez-Nova, Alfonso; Gómez-Martín, Beatriz; Sánchez-Rodríguez, Raquel; Fernández-Seguín, Lourdes María

    2013-01-01

    Fatigue due to running has been shown to contribute to changes in plantar pressure distribution. However, little is known about changes in foot posture after running. We sought to compare the foot posture index before and after moderate exercise and to relate any changes to plantar pressure patterns. A baropodometric evaluation was made, using the FootScan platform (RSscan International, Olen, Belgium), of 30 men who were regular runners and their foot posture was examined using the Foot Posture Index before and after a 60-min continuous run at a moderate pace (3.3 m/sec). Foot posture showed a tendency toward pronation after the 60-min run, gaining 2 points in the foot posture index. The total support and medial heel contact areas increased, as did pressures under the second metatarsal head and medial heel. Continuous running at a moderate speed (3.3 m/sec) induced changes in heel strike related to enhanced pronation posture, indicative of greater stress on that zone after physical activity. This observation may help us understand the functioning of the foot, prevent injuries, and design effective plantar orthoses in sport.

  1. The effects of breath alcohol concentration on postural control.

    Science.gov (United States)

    Fiorentino, Dary D

    2018-05-19

    Two of the 3 standardized field sobriety tests that U.S. law enforcement uses at roadside checks have a postural equilibrium component to them. Those tests have been validated to detect impairment caused by blood alcohol concentrations (BACs) of 0.08 g/dL or above. Many medical and traffic safety associations support a lower limit, and one state, Utah, has passed a law to lower the limit to 0.05 g/dL. Many studies have examined the effects of alcohol on postural control (of which postural equilibrium is a component), with a consensus emerging that impairment is usually found at BACs greater than 0.06 g/dL. Most of these studies, however, had a relatively small number of subjects, usually between 10 and 30. The current study collected data from a much larger sample. The objective of this study was to provide additional evidence that posture control is negatively affected at BACs greater than 0.06 g/dL or breath alcohol concentrations (BrACs) of 0.06 g/210 L. This was a between-subjects study, with BrAC group as the independent variable (5 levels: 0.00, 0.04, 0.06, 0.08, and 0.10 g/210 L); 4 measures of postural control as the dependent variables; and age, height, and weight as the covariates. Posture control was measured with a force-sensing platform connected to a computer. The feet's center of pressure (CoP) on the platform was recorded and the corresponding movement of the body in the anterior-posterior and lateral planes was derived. Participants (N = 96) were randomly assigned to one of the BrAC groups. Positive BrAC groups were compared to the zero BrAC group. Data were examined with hierarchical multiple regression. Adjusted for age, height, and weight, the main effect of lateral CoP with eyes open was not statistically significant. There was a statistically significant main effect of alcohol on anterior-posterior CoP excursion with eyes open and with eyes closed and lateral CoP excursion with eyes closed. For all 3 of those variables, only BrACs of 0

  2. Relationship between Postural Deformities and Frontal Function in Parkinson's Disease

    OpenAIRE

    Ninomiya, Satoko; Morita, Akihiko; Teramoto, Hiroko; Akimoto, Takayoshi; Shiota, Hiroshi; Kamei, Satoshi

    2015-01-01

    Postural deformities and executive dysfunction (ED) are common symptoms of Parkinson's disease (PD); however, the relationship between postural deformities and ED in patients with PD remains unclear. This study assessed the relationship between postural deformities and ED in patients with PD. Sixty-five patients with sporadic PD were assessed for the severity of postural deformities and executive function. The severity of postural deformities was scored using the United Parkinson's Disease Ra...

  3. [Head posture in orthodontics: physiopathology and clinical aspects 2].

    Science.gov (United States)

    Caltabiano, M; Verzi, P; Scire Scappuzzo, G

    1989-01-01

    The Authors review in orthodontic respects present knowledges about head posture involvement in craniofacial morphogenesis and pathology. Relationships between craniofacial morphology, craniocervical posture, craniomandibular posture, cervical spine curvature, hyoid bone position and posture of whole body in space are shown, in attempt to explain conditions such as "forward head posture", mouth breathing and some occlusal disorders. Main methods to evaluate craniocervical relations on lateral skull radiographs are analysed. Pathogenesis of pain syndromes associated with abnormal craniocervical and craniomandibular mechanics are also briefly treated.

  4. Effects of affective picture viewing on postural control

    Directory of Open Access Journals (Sweden)

    Beek Peter J

    2007-10-01

    Full Text Available Abstract Background Emotion theory holds that unpleasant events prime withdrawal actions, whereas pleasant events prime approach actions. Recent studies have suggested that passive viewing of emotion eliciting images results in postural adjustments, which become manifest as changes in body center of pressure (COP trajectories. From those studies it appears that posture is modulated most when viewing pictures with negative valence. The present experiment was conducted to test the hypothesis that pictures with negative valence have a greater impact on postural control than neutral or positive ones. Thirty-four healthy subjects passively viewed a series of emotion eliciting images, while standing either in a bipedal or unipedal stance on a force plate. The images were adopted from the International Affective Picture System (IAPS. We analysed mean and variability of the COP and the length of the associated sway path as a function of emotion. Results The mean position of the COP was unaffected by emotion, but unipedal stance resulted in overall greater body sway than bipedal stance. We found a modest effect of emotion on COP: viewing pictures of mutilation resulted in a smaller sway path, but only in unipedal stance. We obtained valence and arousal ratings of the images with an independent sample of viewers. These subjects rated the unpleasant images as significantly less pleasant than neutral images, and the pleasant images as significantly more pleasant than neutral images. However, the subjects rated the images as overall less pleasant and less arousing than viewers in a closely comparable American study, pointing to unknown differences in viewer characteristics. Conclusion Overall, viewing emotion eliciting images had little effect on body sway. Our finding of a reduction in sway path length when viewing pictures of mutilation was indicative of a freezing strategy, i.e. fear bradycardia. The results are consistent with current knowledge about the

  5. Effects of affective picture viewing on postural control.

    Science.gov (United States)

    Stins, John F; Beek, Peter J

    2007-10-04

    Emotion theory holds that unpleasant events prime withdrawal actions, whereas pleasant events prime approach actions. Recent studies have suggested that passive viewing of emotion eliciting images results in postural adjustments, which become manifest as changes in body center of pressure (COP) trajectories. From those studies it appears that posture is modulated most when viewing pictures with negative valence. The present experiment was conducted to test the hypothesis that pictures with negative valence have a greater impact on postural control than neutral or positive ones. Thirty-four healthy subjects passively viewed a series of emotion eliciting images, while standing either in a bipedal or unipedal stance on a force plate. The images were adopted from the International Affective Picture System (IAPS). We analysed mean and variability of the COP and the length of the associated sway path as a function of emotion. The mean position of the COP was unaffected by emotion, but unipedal stance resulted in overall greater body sway than bipedal stance. We found a modest effect of emotion on COP: viewing pictures of mutilation resulted in a smaller sway path, but only in unipedal stance. We obtained valence and arousal ratings of the images with an independent sample of viewers. These subjects rated the unpleasant images as significantly less pleasant than neutral images, and the pleasant images as significantly more pleasant than neutral images. However, the subjects rated the images as overall less pleasant and less arousing than viewers in a closely comparable American study, pointing to unknown differences in viewer characteristics. Overall, viewing emotion eliciting images had little effect on body sway. Our finding of a reduction in sway path length when viewing pictures of mutilation was indicative of a freezing strategy, i.e. fear bradycardia. The results are consistent with current knowledge about the neuroanatomical organization of the emotion system and

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

    Science.gov (United States)

    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

  7. Postural balance in low back pain patients

    DEFF Research Database (Denmark)

    Maribo, Thomas; Schiøttz-Christensen, Berit; Jensen, Lone Donbæk

    2012-01-01

    INTRODUCTION: Altered postural control has been observed in low back pain (LBP) patients. They seem to be more dependent on vision when standing. The objective of the study was to determine concurrent and predictive validity of measures of postural stability in LBP patients. MATERIALS AND METHODS......: Centre of Pressure (CoP) measurements were tested against pain, fear of pain, and physical function. Velocity, anterior-posterior displacement, and the Romberg Ratio obtained on a portable force platform were used as measures of postural stability. RESULTS: Baseline and 12-week follow-up results of 97....... CONCLUSION: This first study of concurrent and predictive validity of postural balance in LBP patients revealed no association between CoP measures and pain, fear of pain, and physical function....

  8. Postural stability in young and old women

    DEFF Research Database (Denmark)

    Jørgensen, Martin Grønbech

    at an early stage, good knowledge and sensitive measurements of postural stability are essential. In addition, in order to develop effective intervention strategies such knowledge is of major importance. However, no single postural stability parameter has effectively been able to identify individuals at risk...... of falling. Hence, there is a strong need for development and identification of sensitive postural sway parameters in various demographic groups. The aim of this study was to explore differences in postural stability between physically active old (O) and young (Y) women using newly developed sway parameters....... METHODS AND MATERIALS: Center of pressure (CoP) excursion was measured (100 Hz) by force plate (AMTI) analysis in old (72.5±6.3 years) and young (25.8±1.6 years) women during static 2-leg (bilateral) and 1-leg (unilateral) standing (15-s) with eyes opened. RESULTS: O demonstrated elevated CoP sway length...

  9. Impaired postural stability after laparoscopic surgery

    DEFF Research Database (Denmark)

    Eskildsen, K Z; Staehr-Rye, A K; Rasmussen, L S

    2015-01-01

    . METHODS: We included 25 women undergoing outpatient gynaecological laparoscopic surgery in the study. Patients received standardised anaesthesia with propofol, remifentanil and rocuronium. Postural stability was assessed preoperatively, at 30 min after tracheal extubation, and at discharge from the post...

  10. Beyond deficit or compensation: new insights on postural control after long-term total visual loss.

    Science.gov (United States)

    Russo, Maitê M; Lemos, Thiago; Imbiriba, Luís A; Ribeiro, Nathalia L; Vargas, Claudia D

    2017-02-01

    Loss of vision is well known to affect postural control in blind subjects. This effect has classically been framed in terms of deficit or compensation depending on whether body sway increases or decreases in comparison with that of sighted subjects with the eyes open. However, studies have shown that postural responses can be modulated by the context and that changes in postural sway may not necessarily mean a worsened or improved postural control. The goal of our study was to test whether balance is affected by the context in blind subjects. Additional to the quantification of center of pressure (COP) displacement, measurements of body motion (COG) and the correspondent net neuromuscular response (COP-COG) were evaluated in anterior-posterior and medial-lateral directions. Thirty-eight completely blind and thirty-two sighted subjects participated of this study. The volunteers were asked to stand barefoot on a force platform for 60 s in two different conditions: feet apart and feet together. Sighted participants performed the tests with both the eyes open and eyes closed. Results showed that the COP-COG displacements in the blind group were greater than those of the sighted group with eyes open in almost all conditions tested, but not in eyes closed condition. However, the COP and COG results confirmed that the postural responses were context dependent. Together these results suggest that total visual loss does not just lead to a balance deficit or compensation, but to a specific postural signature that might imply in enhancing COP, COG and/or COP-COG in specific postural conditions.

  11. The association between head and cervical posture and temporomandibular disorders: a systematic review.

    Science.gov (United States)

    Olivo, Susan Armijo; Bravo, Jaime; Magee, David J; Thie, Norman M R; Major, Paul W; Flores-Mir, Carlos

    2006-01-01

    To carry out a systematic review to assess the evidence concerning the association between head and cervical posture and temporomandibular disorders (TMD). A search of Medline, Pubmed, Embase, Web of Science, Lilacs, and Cochrane Library databases was conducted in all languages with the help of a health sciences librarian. Key words used in the search were posture, head posture, cervical spine or neck, vertebrae, cervical lordosis, craniomandibular disorders or temporomandibular disorders, temporomandibular disorders, and orofacial pain or facial pain. Abstracts which appeared to fulfill the initial selection criteria were selected by consensus. The original articles were retrieved and evaluated to ensure they met the inclusion criteria. A methodological checklist was used to evaluate the quality of the selected articles and their references were hand-searched for possible missing articles. Twelve studies met all inclusion criteria and were analyzed in detail for their methodology and information quality. Nine articles that analyzed the association between head posture and TMD included patients with mixed TMD diagnosis; 1 article differentiated among muscular, articular, and mixed symptomatology; and 3 articles analyzed information from patients with only articular problems. Finally, 2 studies evaluated the association between head posture and TMD in patients with muscular TMD. Several methodological defects were noted in the 12 studies. Since most of the studies included in this systematic review were of poor methodological quality, the findings of the studies should be interpreted with caution. The association between intra-articular and muscular TMD and head and cervical posture is still unclear, and better controlled studies with comprehensive TMD diagnoses, greater sample sizes, and objective posture evaluation are necessary.

  12. Age-related effects on postural control under multi-task conditions.

    Science.gov (United States)

    Granacher, Urs; Bridenbaugh, Stephanie A; Muehlbauer, Thomas; Wehrle, Anja; Kressig, Reto W

    2011-01-01

    Changes in postural sway and gait patterns due to simultaneously performed cognitive (CI) and/or motor interference (MI) tasks have previously been reported and are associated with an increased risk of falling in older adults. The objectives of this study were to investigate the effects of a CI and/or MI task on static and dynamic postural control in young and elderly subjects, and to find out whether there is an association between measures of static and dynamic postural control while concurrently performing the CI and/or MI task. A total of 36 healthy young (n = 18; age: 22.3 ± 3.0 years; BMI: 21.0 ± 1.6 kg/m(2)) and elderly adults (n = 18; age: 73.5 ± 5.5 years; BMI: 24.2 ± 2.9 kg/m(2)) participated in this study. Static postural control was measured during bipedal stance, and dynamic postural control was obtained while walking on an instrumented walkway. Irrespective of the task condition, i.e. single-task or multiple tasks, elderly participants showed larger center-of-pressure displacements and greater stride-to-stride variability than younger participants. Associations between measures of static and dynamic postural control were found only under the single-task condition in the elderly. Age-related deficits in the postural control system seem to be primarily responsible for the observed results. The weak correlations detected between static and dynamic measures could indicate that fall-risk assessment should incorporate dynamic measures under multi-task conditions, and that skills like erect standing and walking are independent of each other and may have to be trained complementarily. Copyright © 2010 S. Karger AG, Basel.

  13. Postural control among elderly women with and without osteoporosis: is there a difference?

    Directory of Open Access Journals (Sweden)

    Thomaz Nogueira Burke

    Full Text Available CONTEXT AND OBJECTIVE: Little is known about postural control among elderly individuals with osteoporosis and its relationship with falls. It has been suggested that elderly women with kyphosis and osteoporosis are at greater risk of falling. The aim of this study was to evaluate posture and postural control among elderly women with and without osteoporosis. DESIGN AND SETTING: Cross-sectional study conducted at the Physical Therapy and Electromyography Laboratory, School of Medicine, Universidade de São Paulo (USP. METHODS: Sixty-six elderly women were selected from the bone metabolism disorders clinic, Division of Rheumatology, USP, and were divided into two groups: osteoporosis and controls, according to their bone mineral density (BMD. Postural control was assessed using the Limits of Stability (LOS test and the Modified Clinical Test of Sensory Interaction and Balance (CTSIBm and posture, using photometry. RESULTS: The elderly women with osteoporosis swayed at higher velocity on a stable surface with opened eyes (0.30 versus 0.20 degrees/second; P = 0.038. In both groups, the center of pressure (COP was at 30% in the LOS, but with different placements: 156° in the osteoporosis group and 178° in the controls (P = 0.045. Osteoporosis patients fell more than controls did (1.0 versus 0.0; P = 0.036. CONCLUSIONS: The postural control in elderly women with osteoporosis differed from that of the controls, with higher sway velocity and maximum displacement of COP. Despite postural abnormalities such as hyperkyphosis and forward head, the COP position was posteriorized.

  14. Microbunch Instability Theory and Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Stupakov, G.

    2005-01-26

    Over the last years there have been several reports of quasiperiodic bursts of coherent synchrotron radiation (CSR) in electron rings in the microwave and far-infrared range. The observations were made on synchrotron radiation light sources which include the Synchrotron Ultraviolet Radiation Facility SURF II [1], the VUV ring at the National Synchrotron Light Source at BNL [2, 3], second generation light sources MAX-I [4], BESSY II [5], and ALS [6]. General features of those observations can be summarized as follows. Above a threshold current, there is a strongly increased radiation of the beam in the range of wavelengths shorter than the bunch length, {lambda} < {sigma}{sub 2}. At large currents, this radiation is observed as a sequence of random bursts. In the bursting regime, intensity of the radiation scales approximately as square of the number of particles in the bunch, indicating a coherent nature of the phenomenon. It is generally accepted that the source of this radiation is related to the microbunching of the beam arising from development of a microwave instability caused by the coherent synchrotron radiation of the beam. A relativistic electron beam moving in a circular orbit in free space can radiate coherently if the wavelength of the synchrotron radiation exceeds the length of the bunch. In accelerators coherent radiation of the bunch is usually suppressed by the shielding effect of the conducting walls of the vacuum chamber [7-9], which gives an exponential cutoff of wavelengths greater than a certain threshold. However, an initial density fluctuation with a characteristic length much shorter than the shielding threshold would radiate coherently. If the radiation reaction force is such that it results in the growth of the initial fluctuation one can expect an instability that leads to micro-bunching of the beam and an increased coherent radiation at short wavelengths. A possibility of CSR instability was pointed out in Refs. [10, 11].

  15. Effect of absence of vision on posture

    OpenAIRE

    Alotaibi, Abdullah Z.; Alghadir, Ahmad; Iqbal, Zaheen A.; Anwer, Shahnawaz

    2016-01-01

    [Purpose] The visual system is one of the sensory systems that enables the body to assess and process information about the external environment. In the absence of vision, a blind person loses contact with the outside world and develops faulty motor patterns, which results in postural deficiencies. However, literature regarding the development of such deficiencies is limited. The aim of this study was to discuss the effect of absence of vision on posture, the possible biomechanics behind the ...

  16. Posture estimation system for underground mine vehicles

    CSIR Research Space (South Africa)

    Hlophe, K

    2010-09-01

    Full Text Available Page 1 of 8 25th International Conference of CAD/CAM, Robotics & Factories of the Future Conference, 13-16 July 2010, Pretoria, South Africa A POSTURE ESTIMATION SYSTEM FOR UNDERGROUND MINE VEHICLES Khonzumusa Hlophe1, Gideon Ferreira2... and the transmitter. The main difference between the three systems is their implementation. This paper describes an implementation of a posture estimation system for underground mine vehicles. The paper is organized as follows. In the next section, a brief...

  17. Computer use in school: its effect on posture and discomfort in schoolchildren.

    LENUS (Irish Health Repository)

    Kelly, Grace

    2009-01-01

    The aim of the study was to investigate the posture and musculoskeletal discomfort of secondary school students while working at computers in school. Students (n = 40) were observed while working at a computer during their designated computer class. The Rapid Upper Limb Assessment Tool (RULA) was used to assess posture. A Body Discomfort Chart (BDC) and Visual Analogue Scale (VAS) were used to record the area(s) and intensity of musculoskeletal discomfort, if any, experienced by the students at the beginning and end of the computer class. None of the students\\' posture was in the acceptable range (Action Level 1) according to RULA. The majority (65%) were in Action Level 2, 30% were in Action Level 3, and 5% were in Action Level 4. There was a statistically significant increase in reported discomfort from the beginning to the end of the computer class. Longer class length (80 minutes) did not result in greater reporting of discomfort than shorter class length (40 minutes).

  18. Relationship between craniomandibular disorders and poor posture.

    Science.gov (United States)

    Nicolakis, P; Nicolakis, M; Piehslinger, E; Ebenbichler, G; Vachuda, M; Kirtley, C; Fialka-Moser, V

    2000-04-01

    The purpose of this research was to show that a relationship between craniomandibular disorders (CMD) and postural abnormalities has been repeatedly postulated, but still remains unproven. This study was intended to test this hypothesis. Twenty-five CMD patients (mean age 28.2 years) were compared with 25 gender and age matched controls (mean age 28.3 years) in a controlled, investigator-blinded trial. Twelve postural and ten muscle function parameters were examined. Measurements were separated into three subgroups, consisting of those variables associated with the cervical region, the trunk in the frontal plane, and the trunk in the sagittal plane. Within these subgroups, there was significantly more dysfunction in the patients, compared to control subjects (Mann-Whitney U test p Postural and muscle function abnormalities appeared to be more common in the CMD group. Since there is evidence of the mutual influence of posture and the craniomandibular system, control of body posture in CMD patients is recommended, especially if they do not respond to splint therapy. Whether poor posture is the reason or the result of CMD cannot be distinguished by the data presented here.

  19. Plasma physics and instabilities

    International Nuclear Information System (INIS)

    Lashmore-Davies, C.N.

    1981-01-01

    These lectures procide an introduction to the theory of plasmas and their instabilities. Starting from the Bogoliubov, Born, Green, Kirkwood, and Yvon (BBGKY) hierarchy of kinetic equations, the additional concept of self-consistent fields leads to the fundamental Vlasov equation and hence to the warm two-fluid model and the one-fluid MHD, or cold, model. The properties of small-amplitude waves in magnetized (and unmagnetized) plasmas, and the instabilities to which they give rise, are described in some detail, and a complete chapter is devoted to Landau damping. The linear theory of plasma instabilities is illustrated by the current-driven electrostatic kind, with descriptions of the Penrose criterion and the energy principle of ideal MHD. There is a brief account of the application of feedback control. The non-linear theory is represented by three examples: quasi-linear velocity-space instabilities, three-wave instabilities, and the stability of an arbitrarily largeamplitude wave in a plasma. (orig.)

  20. Motor deficits in schizophrenia quantified by nonlinear analysis of postural sway.

    Directory of Open Access Journals (Sweden)

    Jerillyn S Kent

    Full Text Available Motor dysfunction is a consistently reported but understudied aspect of schizophrenia. Postural sway area was examined in individuals with schizophrenia under four conditions with different amounts of visual and proprioceptive feedback: eyes open or closed and feet together or shoulder width apart. The nonlinear complexity of postural sway was assessed by detrended fluctuation analysis (DFA. The schizophrenia group (n = 27 exhibited greater sway area compared to controls (n = 37. Participants with schizophrenia showed increased sway area following the removal of visual input, while this pattern was absent in controls. Examination of DFA revealed decreased complexity of postural sway and abnormal changes in complexity upon removal of visual input in individuals with schizophrenia. Additionally, less complex postural sway was associated with increased symptom severity in participants with schizophrenia. Given the critical involvement of the cerebellum and related circuits in postural stability and sensorimotor integration, these results are consistent with growing evidence of motor, cerebellar, and sensory integration dysfunction in the disorder, and with theoretical models that implicate cerebellar deficits and more general disconnection of function in schizophrenia.

  1. Hippotherapy on postural balance in the sitting position of children with cerebral palsy - Longitudinal study.

    Science.gov (United States)

    Moraes, Andréa Gomes; Copetti, Fernando; Ângelo, Vera Regina; Chiavoloni, Luana; de David, Ana Cristina

    2018-06-11

    To verify the effects of 12, 24, 36 hippotherapy sessions over time on postural balance while sitting in children with cerebral palsy as well the effects of treatment after one interruption period of 45 days. Hippotherapy program with a twice-weekly treatment with a total of 13 children aged 5-10 years old. Measurements of postural balance during sitting were performed using the AMTI AccuSway Plus platform. There was a statistically significant reduction in mediolateral and anteroposterior sway after the first 12 hippotherapy sessions, and further significant sway reduction occurred as the treatment progressed. Changes in the center of pressure displacement velocity variable began to occur after 24 sessions. Seated postural balance improved in children with cerebral palsy, as evidenced by lower COP displacement, particularly after a greater number of sessions. After the last evaluations, when completing 36 sessions of hippotherapy, it was verified that the improvements to the postural balance continued to occur. Therefore, further studies with a longer treatment period may help to clarify if, at some point, there is stabilization in the improvement of postural balance. Furthermore, it is important to analyze the impact of hippotherapy on functional activities over time.

  2. Visual Information and Support Surface for Postural Control in Visual Search Task.

    Science.gov (United States)

    Huang, Chia-Chun; Yang, Chih-Mei

    2016-10-01

    When standing on a reduced support surface, people increase their reliance on visual information to control posture. This assertion was tested in the current study. The effects of imposed motion and support surface on postural control during visual search were investigated. Twelve participants (aged 21 ± 1.8 years; six men and six women) stood on a reduced support surface (45% base of support). In a room that moved back and forth along the anteroposterior axis, participants performed visual search for a given letter in an article. Postural sway variability and head-room coupling were measured. The results of head-room coupling, but not postural sway, supported the assertion that people increase reliance on visual information when standing on a reduced support surface. Whether standing on a whole or reduced surface, people stabilized their posture to perform the visual search tasks. Compared to a fixed target, searching on a hand-held target showed greater head-room coupling when standing on a reduced surface. © The Author(s) 2016.

  3. Posture, head stability, and orientation recovery during vestibular regeneration in pigeons.

    Science.gov (United States)

    Dickman, J David; Lim, Insook

    2004-09-01

    Compensatory behavior such as oculomotor, gaze, and postural responses that occur during movement largely depend upon a functioning vestibular system. In the present study, the initial loss and subsequent recovery of postural and head stability in pigeons undergoing vestibular regeneration were examined. Adult pigeons were trained to manipulate a straight run chamber to peck an illuminated key for fluid reward. Six behavioral measures assessing performance, posture, and head stability were quantified. These included run latency, steps (walking), path negotiation (lane changes), gaze saccades, head bobs, and head shakes. Once normative values were obtained for four birds, complete lesion of all receptor cells and denervation of the epithelia in the vestibular endorgans were produced using a single intralabyrinthine application of streptomycin sulfate. Each bird was then tested at specific times during regeneration and the same behavioral measures examined. At 7 days post-streptomycin treatment (PST), all birds exhibited severe postural and head instability, with tremors, head shakes, staggering, and circling predominating. No normal trial runs, walking, gaze saccades, or head bobs were present. Many of these dysfunctions persisted through 3-4 weeks PST. Gradually, tremor and head shakes diminished and were replaced with an increasing number of normal head bobs during steps and gaze saccades. Beginning at 4 weeks PST, but largely inaccurate, was the observed initiation of directed steps, less staggering, and some successful path negotiation. As regeneration progressed, spatial orientation and navigation ability increased and, by 49 days PST, most trials were successful. By 70 days PST, all birds had recovered to pretreatment levels. Thus, it was observed that ataxia must subside, coincident with normalized head and postural stability prior to the recovery of spatial orientation and path navigation recovery. Parallels in recovery were drawn to hair cell regeneration

  4. Effects of joint mobilization on chronic ankle instability: a randomized controlled trial.

    Science.gov (United States)

    Cruz-Díaz, David; Lomas Vega, Rafael; Osuna-Pérez, Maria Catalina; Hita-Contreras, Fidel; Martínez-Amat, Antonio

    2015-01-01

    To evaluate the effects of joint mobilization, in which movement is applied to the ankle's dorsiflexion range of motion, on dynamic postural control and on the self-reported instability of patients with chronic ankle instability (CAI). A double-blind, placebo-controlled, randomized trial with repeated measures and a follow-up period. Ninety patients with a history of recurrent ankle sprain, self-reported instability, and a limited dorsiflexion range of motion, were randomly assigned to either the intervention group (Joint Mobilizations, 3 weeks, two sessions per week) the placebo group (Sham Mobilizations, same duration as joint mobilization) or the control group, with a 6 months follow-up. Dorsiflexion Range of Motion (DFROM), Star Excursion Balance Test (SEBT) and CAI Tool (CAIT) were outcome measures. A separate 3 × 4 mixed model analysis of variance was performed to examine the effect of treatment conditions and time, and intention-to-treat (ITT) analysis was applied to evaluate the effect of the independent variable. The application of joint mobilization resulted in better scores of DFROM, CAIT, and SEBTs in the intervention group when compared with the placebo or the control groups (p ankle DFROM, postural control, and self-reported instability. These results suggest that joint mobilization could be applied to patients with recurrent ankle sprain to help restore their functional stability. Implications for Rehabilitation Functional instability is a very common sequela in patients with CAI, resulting in reduced quality of living due to the limitations it imposes on daily life activities. The mobilization with movement technique presented by Mulligan, and based on the joint mobilization accompanied by active movement, appears as a valuable tool to be employed by physical therapists to restore ankle function after a recurrent ankle sprain history. ROM restriction, subjective feeling of instability and dynamic postural control are benefiting from the joint

  5. The association of foot arch posture and prior history of shoulder or elbow surgery in elite-level baseball pitchers.

    Science.gov (United States)

    Feigenbaum, Luis A; Roach, Kathryn E; Kaplan, Lee D; Lesniak, Bryson; Cunningham, Sean

    2013-11-01

    Case-control. The specific aim of this study was to examine the association between abnormal foot arch postures and a history of shoulder or elbow surgery in baseball pitchers. Pitching a baseball generates forces throughout the musculoskeletal structures of the upper and lower limbs. Structures such as the longitudinal arch of the foot are adaptable to stresses over time. Repeated pitching-related stresses may contribute to acquiring abnormal foot arch postures. Inversely, congenitally abnormal foot arch posture may lead to altered stresses of the upper limb during pitching. A convenience sample of 77 pitchers was recruited from a Division I university team and a professional baseball franchise. Subjects who had a history of shoulder or elbow surgery to the pitching arm were classified as cases. Subjects who met the criteria for classification of pes planus or pes cavus based on longitudinal arch angle were classified as having abnormal foot arch posture. Odds ratios were calculated to examine the association between abnormal foot arch posture and pitching-arm injury requiring surgery. Twenty-three subjects were classified as cases. The odds of being a case were 3.4 (95% confidence interval: 1.2, 9.6; P = .02) times greater for subjects with abnormal foot arch posture and 2.9 (95% confidence interval: 1.0, 8.1; P = .04) times greater for subjects with abnormal foot posture on the lunge leg. Abnormal foot arch posture and a surgical history in the pitching shoulder or elbow may be associated. Because the foot and its arches are adaptable and change over time, the pathomechanics of this association should be further explored.

  6. Fingerprints of dynamical instabilities

    International Nuclear Information System (INIS)

    Chomaz, Ph.; Colonna, M.; Guarnera, A.

    1993-01-01

    It is explained why any reduced descriptions, such as mean field approximation, are stochastic in nature. It is shown that the introduction of this stochastic dynamics leads to a predictive theory in a statistical sens whatever the individual trajectories are characterized by the occurrence of bifurcations, instabilities or phase transitions. Concerning nuclear matter, the spinodal instability is discussed. In such a critical situation, the possibility to replace the stochastic part of the collision integral in the Boltzmann-Langevin model by the numerical noise associated with the finite number of test particles in ordinary BUU treatment is studied. It is shown that the fingerprints of these instabilities are kept during the evolution because of the relatively long recombination time compared with the typical time scales imposed by the Coulomb repulsion and the possible collective expansion. (author) 5 refs., 12 figs

  7. Instability and star evolution

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.

    1981-01-01

    The observational data are discussed which testify that the phenomena of dynamical instability of stars and stellar systems are definite manifestations of their evolution. The study of these phenomena has shown that the instability is a regular phase of stellar evolution. It has resulted in the recognition of the most important regularities of the process of star formation concerning its nature. This became possible due to the discovery in 1947 of stellar associations in our Galaxy. The results of the study of the dynamical instability of stellar associations contradict the predictions of classical hypothesis of stellar condensation. These data supplied a basis for a new hypothesis on the formation of stars and nebulae by the decay of superdense protostars [ru

  8. Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

    Directory of Open Access Journals (Sweden)

    Brown Cathleen N

    2007-12-01

    Full Text Available Abstract Background Ankle sprains are common injuries that often lead to functional ankle instability (FAI, which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains. Methods This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1 conventional coordination training group (CCT; 2 SR stimulation coordination training group (SCT; or 3 control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P and medial/lateral (M/L center-of-pressure velocity (COPvel, M/L COP standard deviation (COPsd, M/L COP maximum excursion (COPmax, and COP area (COParea. Results Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 ± 0.4 cm/s vs. 2.7 ± 0.6 cm/s, M/L COPvel (2.6 ± 0.5 cm/s vs. 2.9 ± 0.5 cm/s, M/L COPsd (0.63 ± 0.12 cm vs. 0.73 ± 0

  9. Effect of Pregnancy on Postural Tachycardia Syndrome

    Science.gov (United States)

    Kimpinski, Kurt; Iodice, Valeria; Sandroni, Paola; Low, Phillip A.

    2010-01-01

    OBJECTIVES: To compare the clinical presentation, autonomic dysfunction, and pregnancy outcomes in parous and nulliparous women with postural tachycardia syndrome (POTS) and in women with POTS before and after pregnancy. PATIENTS AND METHODS: This study consists of women who had at least 1 pregnancy during which time they met criteria for POTS between May 1993 and July 2009. All patients underwent standard autonomic testing. POTS was defined as a heart rate (HR) increase of greater than 30 beats/min on head-up tilt (HUT) with symptoms of orthostatic intolerance. Patients' charts were reviewed retrospectively to determine pregnancy outcomes. RESULTS: Clinical characteristics related to POTS did not differ between parous and nulliparous women except for disease duration (parous, 3.7±2.6; nulliparous, 2.1±2.2; Pchange in HR on HUT: parous, 42.6±12.0 beats/min; nulliparous, 41.3±10.6 beats/min; P=.39). Of 116 total pregnancies, adverse pregnancy outcomes were reported in 9% and maternal complications in 1%. No complication was related to POTS. There was a trend toward modest improvement in autonomic dysfunction before and after pregnancy (change in HR on HUT: before pregnancy, 38.1±22.7 beats/min; after pregnancy, 21.9±14.9 beats/min; P=.07). CONCLUSION: The long-term impact of pregnancy on POTS does not appear to be clinically important. However, there does appear to be a trend toward improvement in the short-term postpartum period. Adverse pregnancy events were similar to those seen in the general public and do not present a barrier to women with POTS who want to have children. PMID:20516426

  10. Human posture experiments under water: ways of applying the findings to microgravity

    Science.gov (United States)

    Dirlich, Thomas

    differences between underwater and real microgravity environment were analyzed in greater detail: external forces (buoyancy and grav-ity), required fixation, postural changes by breathing and subject orientation to gravitational vector. Goal of this analysis was to understand the respective effects of each environmental influence on subjects posture observed. Each of the different influences was then quantified and the postural change induced by it calculated. These were then combined using a specially programmed multi-body-simulation tool, making it possible to recompute 3D posture data dy-namically to the environmental influences. The simulation is based on the volumetric 3D model of each subject, specific anthropometric data, such as body-fat or muscle ratio, combined with external forces such as gravity and buoyancy. The recomputed data can then be compared independent from the environmental influences. The recomputed 3D posture data can then be re-evaluated focussing again on possible inter-personal neutral posture archetypes in the subject group. Some examples of recomputed data and inter-personal findings will be given.

  11. Anatomy and histochemistry of hindlimb flight posture in birds. I. The extended hindlimb posture of shorebirds.

    Science.gov (United States)

    McFarland, Joshua C; Meyers, Ron A

    2008-08-01

    Birds utilize one of two hindlimb postures during flight: an extended posture (with the hip and knee joints flexed, while the ankle joint is extended caudally) or a flexed posture (with the hip, knee, and ankle joints flexed beneath the body). American Avocets (Recurvirostra americana) and Black-necked Stilts (Himantopus mexicanus) extend their legs caudally during flight and support them for extended periods. Slow tonic and slow twitch muscle fibers are typically found in muscles functioning in postural support due to the fatigue resistance of these fibers. We hypothesized that a set of small muscles composed of high percentages of slow fibers and thus dedicated to postural support would function in securing the legs in the extended posture during flight. This study examined the anatomy and histochemical profile of eleven hindlimb muscles to gain insight into their functional roles during flight. Contrary to our hypothesis, all muscles possessed both fast twitch and slow twitch or slow tonic fibers. We believe this finding is due to the versatility of dynamic and postural functions the leg muscles must facilitate, including standing, walking, running, swimming, and hindlimb support during flight. Whether birds use an extended or flexed hindlimb flight posture may be related to the aerodynamic effect of leg position or may reflect evolutionary history. (c) 2008 Wiley-Liss, Inc.

  12. Causes of genome instability

    DEFF Research Database (Denmark)

    Langie, Sabine A S; Koppen, Gudrun; Desaulniers, Daniel

    2015-01-01

    function, chromosome segregation, telomere length). The purpose of this review is to describe the crucial aspects of genome instability, to outline the ways in which environmental chemicals can affect this cancer hallmark and to identify candidate chemicals for further study. The overall aim is to make......Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus...

  13. Instabilities and nonequilibrium structures

    International Nuclear Information System (INIS)

    Tirapegui, E.; Villarroel, D.

    1987-01-01

    Physical systems can be studied both near to and far from equilibrium where instabilities appear. The behaviour in these two regions is reviewed in this book, from both the theoretical and application points of view. The influence of noise in these situations is an essential feature which cannot be ignored. It is therefore discussed using phenomenological and theoretical approaches for the numerous problems which still remain in the field. This volume should appeal to mathematicians and physicists interested in the areas of instability, bifurcation theory, dynamical systems, pattern formation, nonequilibrium structures and statistical mechanics. (Auth.)

  14. RINGED ACCRETION DISKS: INSTABILITIES

    Energy Technology Data Exchange (ETDEWEB)

    Pugliese, D.; Stuchlík, Z., E-mail: d.pugliese.physics@gmail.com, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

    2016-04-01

    We analyze the possibility that several instability points may be formed, due to the Paczyński mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider a recently proposed model of a ringed accretion disk, made up by several tori (rings) that can be corotating or counter-rotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends on the dimensionless spin of the rotating attractor.

  15. Wavelet Transform Analysis of the Power Spectrum of Centre of Pressure Signals to Detect the Critical Point Interval of Postural Control

    Science.gov (United States)

    Singh, Neeraj Kumar; Snoussi, Hichem; Hewson, David; Duchêne, Jacques

    The aim of this study was to develop a method to detecting the critical point interval (CPI) when sensory feedback is used as part of a closed-loop postural control strategy. Postural balance was evaluated using centre of pressure (COP) displacements from a force plate for 17 control and 10 elderly subjects under eyes open, eyes closed, and vibration conditions. A modified local-maximum-modulus wavelet transform analysis using the power spectrum of COP signals was used to calculate CPI. Lower CPI values indicate increased closed-loop postural control with a quicker response to sensory input. Such a strategy requires greater energy expenditure due to the repeated muscular interventions to remain stable. The CPI for elderly occurred significantly quicker than for controls, indicating tighter control of posture. Similar results were observed for eyes closed and vibration conditions. The CPI parameter can be used to detect differences in postural control due to ageing.

  16. Head movements and postures as pain behavior

    Science.gov (United States)

    Al-Hamadi, Ayoub; Limbrecht-Ecklundt, Kerstin; Walter, Steffen; Traue, Harald C.

    2018-01-01

    Pain assessment can benefit from observation of pain behaviors, such as guarding or facial expression, and observational pain scales are widely used in clinical practice with nonverbal patients. However, little is known about head movements and postures in the context of pain. In this regard, we analyze videos of three publically available datasets. The BioVid dataset was recorded with healthy participants subjected to painful heat stimuli. In the BP4D dataset, healthy participants performed a cold-pressor test and several other tasks (meant to elicit emotion). The UNBC dataset videos show shoulder pain patients during range-of-motion tests to their affected and unaffected limbs. In all videos, participants were sitting in an upright position. We studied head movements and postures that occurred during the painful and control trials by measuring head orientation from video over time, followed by analyzing posture and movement summary statistics and occurrence frequencies of typical postures and movements. We found significant differences between pain and control trials with analyses of variance and binomial tests. In BioVid and BP4D, pain was accompanied by head movements and postures that tend to be oriented downwards or towards the pain site. We also found differences in movement range and speed in all three datasets. The results suggest that head movements and postures should be considered for pain assessment and research. As additional pain indicators, they possibly might improve pain management whenever behavior is assessed, especially in nonverbal individuals such as infants or patients with dementia. However, in advance more research is needed to identify specific head movements and postures in pain patients. PMID:29444153

  17. Postural Response Signal Characteristics Identified by Method of Developed Statokinesigram

    Directory of Open Access Journals (Sweden)

    Barbolyas Boris

    2015-12-01

    Full Text Available Human postural system is taken as complex biological system with specific input and output time characteristics, in this study. Evaluation of measured output characteristics is useful in medical diagnostics or in describing postural system disorders. System theory principle provide suitable basis for postural signals analysis. Participating volunteers were instructed to maintain quiet upright stance posture on firm support surface of stabilometric platform for 60s. Postural system actuation was realized by vibration stimuli applied bilaterally on Achilles tendons for 20s. Postural reaction signal, its time profile and static and dynamic characteristics were evaluated by Method of Developed Statokinesigram Trajectory (MDST.

  18. Buneman instability and Pierce instability in a collisionless bounded plasma

    International Nuclear Information System (INIS)

    Iizuka, Satoru; Saeki, Koichi; Sato, Noriyoshi; Hatta, Yoshisuke

    1983-01-01

    A systematic experiment is performed on the Buneman instability and the Pierce instability in a bounded plasma consisting of beam electrons and stationary ions. Current fluctuations are confirmed to be induced by the Buneman instability. On the other hand, the Pierce instability gives rise to a current limitation. The phenomena are well explained by Mikhailovskii's theory taking account of ion motion in a bounded plasma. (author)

  19. Elbow joint instability

    DEFF Research Database (Denmark)

    Olsen, Bo Sanderhoff; Henriksen, M G; Søjbjerg, Jens Ole

    1994-01-01

    The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the elbow joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant elbow joint instability in valgus and varus...

  20. Structural and Material Instability

    DEFF Research Database (Denmark)

    Cifuentes, Gustavo Cifuentes

    This work is a small contribution to the general problem of structural and material instability. In this work, the main subject is the analysis of cracking and failure of structural elements made from quasi-brittle materials like concrete. The analysis is made using the finite element method. Three...

  1. Agricultural Markets Instability

    NARCIS (Netherlands)

    Garrido, A.; Brümmer, B.; M'Barek, R.; Gielen-Meuwissen, M.P.M.; Morales-Opazo, C.

    2016-01-01

    Since the financial and food price crises of 2007, market instability has been a topic of major concern to agricultural economists and policy professionals. This volume provides an overview of the key issues surrounding food prices volatility, focusing primarily on drivers, long-term implications of

  2. Comment on critical instability

    International Nuclear Information System (INIS)

    King, S.F.; Suzuki, Mahiko

    1992-01-01

    We discuss the problem of the mass splitting between top and bottom quarks, within the context of Nambu-Jona-Lasinio type models involving top and bottom quark condensates. We interpret the phenomenon of 'critical instability' recently proposed to account for such a mass splitting as the fine-tuning of two vacuum expectation values in a composite two-Higgs doublet model. (orig.)

  3. Effect of absence of vision on posture.

    Science.gov (United States)

    Alotaibi, Abdullah Z; Alghadir, Ahmad; Iqbal, Zaheen A; Anwer, Shahnawaz

    2016-04-01

    [Purpose] The visual system is one of the sensory systems that enables the body to assess and process information about the external environment. In the absence of vision, a blind person loses contact with the outside world and develops faulty motor patterns, which results in postural deficiencies. However, literature regarding the development of such deficiencies is limited. The aim of this study was to discuss the effect of absence of vision on posture, the possible biomechanics behind the resulting postural deficiencies, and strategies to correct and prevent them. [Subjects and Methods] Various electronic databases including PubMed, Medline, and Google scholar were examined using the words "body", "posture", "blind" and "absence of vision". References in the retrieved articles were also examined for cross-references. The search was limited to articles in the English language. [Results] A total of 74 papers were shortlisted for this review, most of which dated back to the 1950s and 60s. [Conclusion] Blind people exhibit consistent musculoskeletal deformities. Absence of vision leads to numerous abnormal sensory and motor interactions that often limit blind people in isolation. Rehabilitation of the blind is a multidisciplinary task. Specialists from different fields need to diagnose and treat the deficiencies of the blind together as a team. Before restoring the normal mechanics of posture and gait, the missing link with the external world should be reestablished.

  4. 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.

  5. Tracking Code for Microwave Instability

    International Nuclear Information System (INIS)

    Heifets, S.; SLAC

    2006-01-01

    To study microwave instability the tracking code is developed. For bench marking, results are compared with Oide-Yokoya results [1] for broad-band Q = 1 impedance. Results hint to two possible mechanisms determining the threshold of instability

  6. Instabilities in thin tunnel junctions

    International Nuclear Information System (INIS)

    Konkin, M.K.; Adler, J.G.

    1978-01-01

    Tunnel junctions prepared for inelastic electron tunneling spectroscopy are often plagued by instabilities in the 0-500-meV range. This paper relates the bias at which the instability occurs to the barrier thickness

  7. Collective instabilities of self-gravitating systems, 2

    International Nuclear Information System (INIS)

    Nakamura, Takashi; Takahara, Fumio; Ikeuchi, Satoru

    1975-01-01

    The instability modes of rotating self-gravitating systems are investigated on the assumption of infinitely long cylinder. The systems under consideration are a collisionless stellar system with anisotropic velocity dispersion and a gaseous system with anisotropic pressure. In the collisionless stellar system, the Jeans instability mode and the Harris instability mode exist. The dispersion relation is solved numerically and the following results are obtained: the Harris instability occurs even in the region where Wu did not treat, and although its growth rate amounts to the order of angular velocity of the system for sufficient anisotropy, the Harris instability always accompanies the Jeans instability and the latter is always greater than the former in growth rate. In the gaseous system exist the Jeans instability mode and a certain overstable mode, which are different from the Harris instability mode. It is shown that the overstable mode occurs due to coupling of modes. In relation to these results, some problems in galactic structure are discussed. (auth.)

  8. Nonlinear evolution of MHD instabilities

    International Nuclear Information System (INIS)

    Bateman, G.; Hicks, H.R.; Wooten, J.W.; Dory, R.A.

    1975-01-01

    A 3-D nonlinear MHD computer code was used to study the time evolution of internal instabilities. Velocity vortex cells are observed to persist into the nonlinear evolution. Pressure and density profiles convect around these cells for a weak localized instability, or convect into the wall for a strong instability. (U.S.)

  9. Neck pain and postural balance among workers with high postural demands - a cross-sectional study

    Science.gov (United States)

    2011-01-01

    Background Neck pain is related to impaired postural balance among patients and is highly prevalent among workers with high postural demands, for example, cleaners. We therefore hypothesised, that cleaners with neck pain suffer from postural dysfunction. This cross-sectional study tested if cleaners with neck pain have an impaired postural balance compared with cleaners without neck pain. Methods Postural balance of 194 cleaners with (n = 85) and without (N = 109) neck pain was studied using three different tests. Success or failure to maintain the standing position for 30 s in unilateral stance was recorded. Participants were asked to stand on a force platform for 30 s in the Romberg position with eyes open and closed. The centre of pressure of the sway was calculated, and separated into a slow (rambling) and fast (trembling) component. Subsequently, the 95% confidence ellipse area (CEA) was calculated. Furthermore a perturbation test was performed. Results More cleaners with neck pain (81%) failed the unilateral stance compared with cleaners without neck pain (61%) (p neck pain in comparison with cleaners without neck pain in the Romberg position with eyes closed, but not with eyes open. Conclusions Postural balance is impaired among cleaners with neck pain and the current study suggests a particular role of the slow component of postural sway. Furthermore, the unilateral stance test is a simple test to illustrate functional impairment among cleaners with concurrent neck and low back pain. Trial registration ISRCTN96241850 PMID:21806796

  10. Equilíbrio postural de atletas remadores Equilibrio postural de atletas remadores Postural balance in rowing athletes

    Directory of Open Access Journals (Sweden)

    Taian de Mello Martins Vieira

    2006-06-01

    movimientos laterales y antero-posterior, y el área elíptica del movimiento del centro de presión en el plano de la plataforma. El grupo de atletas no presentó diferencias significativas en los parámetros durante toda la prueba. El grupo de control presentó valores significativamente mas elevados en el área elíptica y la velocidad media a partir de la mitad del test. Los atletas presentaron valores significativamente menores para la escala de Borg, representando mayor resistencia a la incomodidad generada por la actividad. Con base en los resultados, se sugiere que las alteraciones estabilométricas presentadas por el grupo de no atletas sean provenientes de procesos fisiológicos periféricos y que el condicionamiento físico parece ser un factor importante en la manutención del equilibrio estático durante períodos prolongados.The influence of fitness on long-term postural balance is not clear yet. This study aims to compare stabilometric parameters in long-term balance tests performed by rowing athletes and by a control group of non-athletes healthy subjects, who stood upright on a force plate for 31 minutes. At every five minutes of test, a modified Borg scale was shown to the subjects to score the discomfort. The parameters studied were: standard deviation, average velocity and average frequency of the lateral and anterior-posterior centre of pressure displacements, and the elliptical area of the displacement on the level of the force plate. The athletes did not show significant differences in parameters during the entire test. The control group presented significant higher values in the elliptical area and in average velocity from the middle to the end of test. The athletes presented significant lower values in Borg's scale, showing a greater resistance to discomfort. It is suggested that stabilometric alterations showed by the non-athletes occurred in response to peripheral physiological processes, and that physical fitness seems to be an important factor for

  11. Effects of vision and cognitive load on static postural control in subjects with and without patellofemoral pain syndrome.

    Science.gov (United States)

    Zeinalzadeh, Afsaneh; Talebian, Saeed; Naghdi, Soofia; Salavati, Mahyar; Nazary-Moghadam, Salman; Zeynalzadeh Ghoochani, Bahareh

    2018-04-01

    To compare the effects of vision and cognitive load on static postural control in subjects with and without patellofemoral pain syndrome (PFPS). Twenty-eight PFPS patients and 28 controls participated in the study. Postural control was assessed in isolation as well as with visual manipulation and cognitive loading on symptomatic limb. The outcome measures of postural control were quantified in terms of area, anterior-posterior (AP), medial-lateral (ML), and mean velocity (MV) of the displacements of center of pressure (COP). In addition, cognitive performance (auditory Stroop task) was measured in the forms of average reaction time and error ratio in baseline (sitting) and different postural conditions. PFPS subjects showed greater increases in area (p = 0.01), AP (p = 0.01), and ML (p = 0.05) displacements of COP in the blindfolded tasks as compared to control group. However, cognitive load did not differently affect postural control in the two groups. Although PFPS and control group had similar reaction times in the sitting position (p = 0.29), PFPS subjects had longer reaction times than healthy subjects in dual task conditions (p = 0.04). Visual inputs seem to be essential for discriminating postural control between PFPS and healthy individuals. PFPS patients biased toward decreasing cognitive performance more than healthy subjects when they perform the single leg stance and cognitive task concurrently.

  12. Is postural control affected by expertise in alpine skiing?

    OpenAIRE

    Noe, F; Paillard, T

    2005-01-01

    Objectives: This study examined the postural performance of two groups of male skiers competing at different levels and the consequences on postural control of the suppression of visual afferences by eye closure.

  13. Postural hygiene program to prevent low back pain.

    Science.gov (United States)

    Méndez, F J; Gómez-Conesa, A

    2001-06-01

    A quasi-experimental study with 3 x 4 design was performed. To improve the level of knowledge and motor skills and thereby avert the development of painful symptoms. Despite the fact that low back pain affects a high percentage of the population, little research has been carried out to prevent low back pain through health education. The participants in this study were 106 third-grade (9-year-old) students. The program included 11 sessions. The teacher attended the placebo group sessions. No intervention was used with the control group. The level of knowledge and motor skills in the experimental group showed a significant increase immediately after the intervention finished, and at 6- and 12-month intervals after completion of the postural hygiene program (P = 0.00). Some positive changes were generalized to natural situations (P = 0.00). In an independent health check carried out by the local school health services 4 years after application of the postural hygiene program, the results tended slightly to favor the experimental condition over the control conditions (placebo + no intervention). A greater number of the control subjects required medical treatment for low back pain, although this difference was only marginally significant (P = 0.07). The findings from this study support the hypothesis that programs involving practice and motivating strategies impart health knowledge and habits more efficiently than those restricted to the mere transmission of information.

  14. Femoral strength and posture in terrestrial birds and non-avian theropods.

    Science.gov (United States)

    Farke, Andrew A; Alicea, Justy

    2009-09-01

    Osteological and experimental evidence suggest a change in femoral posture between non-avian dinosaurs (in which the femur presumably was carried in a subvertical position) and birds (in which the femur is held nearly horizontal during most phases of terrestrial locomotion). In this study, we used a broad comparative sample to test the hypothesis that cross-sectional properties of the femur records evidence of this presumed change in posture. I(max) and I(min) (second moment of area, related to resistance to bending) and cross-sectional area (indicating resistance to compression) were measured from computed tomography scans of the femora of 30 species of flightless or primarily terrestrial birds, one probable non-dinosaur dinosauromorph, and at least four species of non-avian theropods. It was predicted that birds should have more eccentrically shaped femoral midshafts as measured by I(max)/II(min) (reflecting greater bending) and comparatively smaller cross-sectional areas than non-avians. Results show that no significant differences occur between non-avian dinosaurs and birds for any parameter, and the samples overlapped broadly in many cases. Thus, cross-sectional properties cannot be used to infer differences in femoral posture between the two groups. This surprising finding might be explained by the fact that femoral postures were not drastically different or that a gradation of postures occurred in each sample. It is also possible that bone loading during life was not closely correlated with cross-sectional morphology. We conclude that cross-sectional properties should be used with caution in determining the posture and behaviors of extinct animals, and only in conjunction with other morphological information. (c) 2009 Wiley-Liss, Inc.

  15. Improvement of posture stability by vibratory stimulation following anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Brunetti, O; Filippi, G M; Lorenzini, M; Liti, A; Panichi, R; Roscini, M; Pettorossi, V E; Cerulli, G

    2006-11-01

    Surgical reconstruction of the anterior cruciate ligament (ACL) may reduce, but it does not always eliminate, knee and body instability because of a persisting proprioceptive deficit. In order to enhance body stability, a new protocol of treatment has been proposed consisting of mechanical vibration (100 Hz frequency and < 20 microm amplitude) of the quadriceps muscle in the leg that has undergone ACL reconstruction. In our trials, stimulation was performed when the quadriceps muscle was kept isometrically contracted. Treatment was started one month after surgery. Vibration was applied for short periods over three consecutive days. Nine months after treatment, postural stability was re-evaluated with the subjects standing on one leg with open and with closed eyes. The postural stability of the subjects having undergone vibration treatment, standing on the operated leg was significantly improved one day after treatment when evaluated as mean of speed and elliptic area of the center of pressure. The improvement persisted and increased during the following weeks. Peak torques of the operated leg extensor muscles also increased and reached values close to that of the leg, which had not been operated. Conversely, the balance of the untreated subjects standing on the operated leg did not improve and the restoration of the extensor muscle peak torque was poor. It is concluded that short lasting proprioceptive activation by vibration may lead to a faster and more complete equilibrium recovery probably by permanently changing the network controlling knee posture.

  16. Elderly individuals with increased risk of falls show postural balance impairment

    Directory of Open Access Journals (Sweden)

    Márcio Rogério de Oliveira

    Full Text Available Introduction Falls are a serious public health problem. Objective The aim of this study was to evaluate whether elderly individuals with increased risk of falls have a postural balance deficit, evaluated using a force platform during a one-leg stance. Materials and methods The sample consisted of 94 physically independent elderly individuals from the EELO project. The instruments used were the Downton scale, in order to assess the risk as well as the history of falls, and the force platform to measure postural balance through parameters from the center of pressure (COP. Results Elderly individuals were split into two groups according to the score observed with the Downton scale: G1 — low fall risk (score ≤ 2 — and G2 — high fall risk (score > 2. No differences were observed between the groups concerning gender (P > 0.05, Chi Square test. On the other hand, individuals from G2 showed postural instability when compared to individuals from G1, and individuals from G2 showed higher values in all COP parameters analysed (Mann-Whitney test, P < 0.05. Conclusion It can be concluded that the Downton scale has sensitivity for identifying individuals with balance impairment as well as a risk of falls. Therefore, it may be suggested that this scale may be useful in primary health care for detecting falls in the elderly.

  17. Classifying Transition Behaviour in Postural Activity Monitoring

    Directory of Open Access Journals (Sweden)

    James BRUSEY

    2009-10-01

    Full Text Available A few accelerometers positioned on different parts of the body can be used to accurately classify steady state behaviour, such as walking, running, or sitting. Such systems are usually built using supervised learning approaches. Transitions between postures are, however, difficult to deal with using posture classification systems proposed to date, since there is no label set for intermediary postures and also the exact point at which the transition occurs can sometimes be hard to pinpoint. The usual bypass when using supervised learning to train such systems is to discard a section of the dataset around each transition. This leads to poorer classification performance when the systems are deployed out of the laboratory and used on-line, particularly if the regimes monitored involve fast paced activity changes. Time-based filtering that takes advantage of sequential patterns is a potential mechanism to improve posture classification accuracy in such real-life applications. Also, such filtering should reduce the number of event messages needed to be sent across a wireless network to track posture remotely, hence extending the system’s life. To support time-based filtering, understanding transitions, which are the major event generators in a classification system, is a key. This work examines three approaches to post-process the output of a posture classifier using time-based filtering: a naïve voting scheme, an exponentially weighted voting scheme, and a Bayes filter. Best performance is obtained from the exponentially weighted voting scheme although it is suspected that a more sophisticated treatment of the Bayes filter might yield better results.

  18. Effects of posture on postoperative pulmonary function

    DEFF Research Database (Denmark)

    Nielsen, K G; Holte, Kathrine; Kehlet, H

    2003-01-01

    BACKGROUND: Pulmonary morbidity is still a relevant complication to major surgery despite improvements in surgical technique and anaesthetic methods. Postoperative posture may be a pathogenic factor, but the effects of changes in postoperative posture on pulmonary function have not been reviewed....... METHODS: Review of controlled, clinical trials evaluating postoperative pulmonary function in patients positioned in the supine vs. the sitting or standing position and patients positioned in the supine vs. the lateral position. Data were obtained from a search in the Medline and Cochrane databases (1966...

  19. Reliability of photogrammetry in the evaluation of the postural aspects of individuals with structural scoliosis.

    Science.gov (United States)

    Saad, Karen Ruggeri; Colombo, Alexandra Siqueira; Ribeiro, Ana Paula; João, Sílvia Maria Amado

    2012-04-01

    The purpose of this study was to investigate the reliability of photogrammetry in the measurement of the postural deviations in individuals with idiopathic scoliosis. Twenty participants with scoliosis (17 women and three men), with a mean age of 23.1 ± 9 yrs, were photographed from the posterior and lateral views. The postural aspects were measured with CorelDRAW software. High inter-rater and test-retest reliability indices were found. It was observed that with more severity of scoliosis, greater were the variations between the thoracic kyphosis and lumbar lordosis measures obtained by the same examiner from the left lateral view photographs. A greater body mass index (BMI) was associated with greater variability of the trunk rotation measures obtained by two independent examiners from the right, lateral view (r = 0.656; p = 0.002). The severity of scoliosis was also associated with greater inter-rater variability measures of trunk rotation obtained from the left, lateral view (r = 0.483; p = 0.036). Photogrammetry demonstrated to be a reliable method for the measurement of postural deviations from the posterior and lateral views of individuals with idiopathic scoliosis and could be complementarily employed for the assessment procedures, which could reduce the number of X-rays used for the follow-up assessments of these individuals. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Adiposity and postural balance control: correlations between bioelectrical impedance and stabilometric signals in elderly Brazilian women

    Directory of Open Access Journals (Sweden)

    Míriam Raquel Meira Mainenti

    2011-01-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the correlation between body adiposity and postural control in elderly women. INTRODUCTION: Aging and obesity account for a significant portion of healthcare spending. Life expectancy is increasing worldwide, and Rio de Janeiro has the largest proportion of elderly residents of all Brazilian states. METHODS: A total of 45 women underwent bioelectrical impedance analysis, waist circumference measurements, weight and height measurements, and stabilometric tests in eight different stance conditions (opened and closed bases with both eyes opened and closed and right and left tandem and unilateral stances with eyes opened. During unilateral stances, the number of hand or foot contacts was counted. RESULTS: Weight, body mass index, waist circumference, fat percentage, and fat mass showed statistically significant (p,0.05 and positive correlations with the number of contacts made during unilateral stances. The subjects with greater fat mass showed significantly higher anterior-posterior standard deviation and range when their eyes were closed. The sway area was also greater for this group in opened base when their eyes were closed. DISCUSSION: The results relating body adiposity and postural control can be explained by the difficulty of maintaining a greater quantity of body fat mass within the limits of the individual support base, especially while assuming a unilateral stance. CONCLUSION: The subjects with a greater fat mass exhibited poor balance control, indicating that body adiposity level was associated with postural control in the elderly women examined in the present study.

  1. Interest of active posturography to detect age-related and early Parkinson's disease-related impairments in mediolateral postural control.

    Science.gov (United States)

    Bonnet, Cédrick T; Delval, Arnaud; Defebvre, Luc

    2014-11-15

    Patients with Parkinson's disease display impairments of postural control most particularly in active, challenging conditions. The objective of the present study was to analyze early signs of disease-related and also age-related impairments in mediolateral body extension and postural control. Fifty-five participants (18 Hoehn and Yahr stage 2 patients in the off-drug condition, 18 healthy elderly control subjects, and 19 young adults) were included in the study. The participants performed a quiet stance task and two active tasks that analyzed the performance in mediolateral body motion: a limit of stability and a rhythmic weight shift task. As expected, the patients displayed significantly lower and slower body displacement (head, neck, lower back, center of pressure) than elderly control subjects when performing the two body excursion tasks. However, the behavioral variability in both tasks was similar between the groups. Under these active conditions, the patients showed significantly lower contribution of the hip postural control mechanisms compared with the elderly control subjects. Overall, the patients seemed to lower their performance in order to prevent a mediolateral postural instability. However, these patients, at an early stage of their disease, were not unstable in quiet stance. Complementarily, elderly control subjects displayed slower body performance than young adults, which therefore showed an additional age-related impairment in mediolateral postural control. Overall, the study illustrated markers of age-related and Parkinson's disease impairments in mediolateral postural control that may constrain everyday activities in elderly adults and even more in patients with Parkinson's disease. Copyright © 2014 the American Physiological Society.

  2. Spinal cord stimulation for the treatment of abnormal posture and gait disorder in patients with Parkinson's disease.

    Science.gov (United States)

    Agari, Takashi; Date, Isao

    2012-01-01

    Patients with advanced Parkinson's disease (PD) often present with axial symptoms, including abnormal posture, postural instability, and gait disorder. Although spinal cord stimulation (SCS) is effective for pain, little is known about the effect of SCS on motor function in PD patients. The present study investigated the effect of SCS on posture and gait in 15 PD patients, 5 men and 10 women aged 63-79 years (mean 71.1 years), with low back pain and leg pain who received SCS. A visual analog scale (VAS) was used for pain evaluation pre- and postoperatively. The Unified Parkinson's Disease Rating Scale, Timed Up and Go tests, and Timed 10-Meter Walk tests were used to evaluate motor function and activities of daily living of patients. Preoperative mean VAS score was 8.9 (range 7.8-10), which showed significant postoperative improvement at 3 months to mean VAS score of 2.0 (range 0-3.3). The improvements in VAS scores persisted at 12 months after surgery with mean VAS score of 2.3 (range 0-4). Posture and postural stability motor subscores were improved at 3 months after SCS, and gait had significantly improved at 3 months and 1 year after surgery. Timed 10-Meter Walk tests also demonstrated that patient gait was significantly improved at 3 months and 12 months after surgery. Most advanced stage PD patients suffer considerable pain that causes abnormal posture and gait disturbance. SCS is expected to lead to both amelioration of pain and improvement of motor function in such patients.

  3. Instabilities in strongly coupled plasmas

    CERN Document Server

    Kalman, G J

    2003-01-01

    The conventional Vlasov treatment of beam-plasma instabilities is inappropriate when the plasma is strongly coupled. In the strongly coupled liquid state, the strong correlations between the dust grains fundamentally affect the conditions for instability. In the crystalline state, the inherent anisotropy couples the longitudinal and transverse polarizations, and results in unstable excitations in both polarizations. We summarize analyses of resonant and non-resonant, as well as resistive instabilities. We consider both ion-dust streaming and dust beam-plasma instabilities. Strong coupling, in general, leads to an enhancement of the growth rates. In the crystalline phase, a resonant transverse instability can be excited.

  4. Orphans and political instability.

    Science.gov (United States)

    Breuning, Marijke; Ishiyama, John

    2011-01-01

    This study investigates the security implications of growing orphan populations, particularly in Sub-Saharan Africa. Little has been written about the security implications of this especially vulnerable group of children. Are growing orphan populations associated with increases in political instability as has been suggested? Using data from several sources, we employ regression analysis to test whether Sub-Saharan African countries with larger proportions of orphans and those with increasing orphan populations experience higher rates of political instability. We find that the increase in the orphan population is related to an increasing incidence of civil conflict, but do not find a similar relationship for the proportion of orphans. In addition, we find that the causes of orphanhood matter. We conclude that increases in orphan populations (rather than simple proportions) are destabilizing. We suggest possible avenues for mediating the security risks posed by growing orphan populations.

  5. A trickle instability

    Science.gov (United States)

    Bossa, Benjamin

    2005-11-01

    We address the problem of the free fall of a long, horizontal and narrow liquid layer squeezed in a vertical open Hele-Shaw cell. The layer destabilizes as it falls down, evolving into a series of liquid blobs linked together by thin bridges, which ultimately break, leaving the initially connex fluid layer as a set a disjointed drops. The mechanism of this instability is the onset of a vertical pressure gradient due to the curvature difference of the moving contact line between the advancing interface and the rear interface. This instability, whose growth rate scales with a non-trivial power of the capillary number, amplifies indifferently a broad band of wavenumbers because of the flat shape of its dispersion relation in the thin layer limit. We will finally comment on the nature of the final fragmentation process and drop size distributions.

  6. Instability and internet design

    Directory of Open Access Journals (Sweden)

    Sandra Braman

    2016-09-01

    Full Text Available Instability - unpredictable but constant change in one’s environment and the means with which one deals with it - has replaced convergence as the focal problem for telecommunications policy in general and internet policy in particular. Those who designed what we now call the internet during the first decade of the effort (1969-1979, who in essence served simultaneously as its policy-makers, developed techniques for coping with instability of value for network designers today and for those involved with any kind of large-scale sociotechnical infrastructure. Analysis of the technical document series that was medium for and record of that design process reveals coping techniques that began with defining the problem and went on to include conceptual labour, social practices, and technical approaches.

  7. Imaging of patellofemoral instability

    International Nuclear Information System (INIS)

    Waldt, S.; Rummeny, E.J.

    2012-01-01

    Patellofemoral instability remains a diagnostic and therapeutic challenge due to its multifactorial genesis. The purpose of imaging is to systematically analyze predisposing factors, such as trochlear dysplasia, patella alta, tibial tuberosity-trochlear groove (TT-TG) distance, rotational deformities of the lower limb and patellar tilt. In order to evaluate anatomical abnormalities with a sufficient diagnostic accuracy, standardized measurement methods and implementation of various imaging modalities are necessary. Diagnosis of acute and often overlooked lateral patellar dislocation can be established with magnetic resonance imaging (MRI) because of its characteristic patterns of injury. Damage to the medial patellofemoral ligament (MPFL) has a significance just as high as the predisposing risk factors in relation to the cause of chronic instability. (orig.) [de

  8. Linear waves and instabilities

    International Nuclear Information System (INIS)

    Bers, A.

    1975-01-01

    The electrodynamic equations for small-amplitude waves and their dispersion relation in a homogeneous plasma are outlined. For such waves, energy and momentum, and their flow and transformation, are described. Perturbation theory of waves is treated and applied to linear coupling of waves, and the resulting instabilities from such interactions between active and passive waves. Linear stability analysis in time and space is described where the time-asymptotic, time-space Green's function for an arbitrary dispersion relation is developed. The perturbation theory of waves is applied to nonlinear coupling, with particular emphasis on pump-driven interactions of waves. Details of the time--space evolution of instabilities due to coupling are given. (U.S.)

  9. Cosmic ray driven instability

    International Nuclear Information System (INIS)

    Dorfi, E.A.; Drury, L.O.

    1985-01-01

    The interaction between energetic charged particles and thermal plasma, which forms the basis of diffusive shock acceleration, leads also to interesting dynamical phenomena. For a compressional mode propagating in a system with homoeneous energetic particle pressure it is well known that friction with the energetic particles leads to damping. The linear theory of this effect has been analyzed in detail by Ptuskin. Not so obvious is that a non-uniform energetic particle pressure can in addition amplify compressional disturbances. If the pressure gradient is sufficiently steep this growth can dominate the frictional damping and lead to an instability. It is important to not that this effect results from the collective nature of the interaction between the energetic particles and the gas and is not connected with the Parker instability, nor with the resonant amplification of Alfven waves

  10. Development of the Coordination between Posture and Manual Control

    Science.gov (United States)

    Haddad, Jeffrey M.; Claxton, Laura J.; Keen, Rachel; Berthier, Neil E.; Riccio, Gary E.; Hamill, Joseph; Van Emmerik, Richard E. A.

    2012-01-01

    Studies have suggested that proper postural control is essential for the development of reaching. However, little research has examined the development of the coordination between posture and manual control throughout childhood. We investigated the coordination between posture and manual control in children (7- and 10-year-olds) and adults during…

  11. Postural Control in Children: Implications for Pediatric Practice

    Science.gov (United States)

    Westcott, Sarah L.; Burtner, Patricia

    2004-01-01

    Based on a systems theory of motor control, reactive postural control (RPA) and anticipatory postural control (APA) in children are reviewed from several perspectives in order to develop an evidence-based intervention strategy for improving postural control in children with limitations in motor function. Research on development of postural…

  12. Decrease in back strength in asymmetric trunk postures

    NARCIS (Netherlands)

    Vink, P.; Daanen, H. A M; Meijst, W. J.; Ligteringen, J.

    1992-01-01

    The extension force against resistance was recorded in 23 postures for 12 subjects to find explanations for the decrease in back strength in asymmetric postures. A reduction in muscle force in asymmetric postures was found up to 40%, but was strongly dependent on the plane in which asymmetry

  13. Instability in dynamic fracture

    Science.gov (United States)

    Fineberg, J.; Marder, M.

    1999-05-01

    The fracture of brittle amorphous materials is an especially challenging problem, because the way a large object shatters is intimately tied to details of cohesion at microscopic scales. This subject has been plagued by conceptual puzzles, and to make matters worse, experiments seemed to contradict the most firmly established theories. In this review, we will show that the theory and experiments fit within a coherent picture where dynamic instabilities of a crack tip play a crucial role. To accomplish this task, we first summarize the central results of linear elastic dynamic fracture mechanics, an elegant and powerful description of crack motion from the continuum perspective. We point out that this theory is unable to make predictions without additional input, information that must come either from experiment, or from other types of theories. We then proceed to discuss some of the most important experimental observations, and the methods that were used to obtain the them. Once the flux of energy to a crack tip passes a critical value, the crack becomes unstable, and it propagates in increasingly complicated ways. As a result, the crack cannot travel as quickly as theory had supposed, fracture surfaces become rough, it begins to branch and radiate sound, and the energy cost for crack motion increases considerably. All these phenomena are perfectly consistent with the continuum theory, but are not described by it. Therefore, we close the review with an account of theoretical and numerical work that attempts to explain the instabilities. Currently, the experimental understanding of crack tip instabilities in brittle amorphous materials is fairly detailed. We also have a detailed theoretical understanding of crack tip instabilities in crystals, reproducing qualitatively many features of the experiments, while numerical work is beginning to make the missing connections between experiment and theory.

  14. Relativistic centrifugal instability

    Science.gov (United States)

    Gourgouliatos, Konstantinos N.; Komissarov, Serguei S.

    2018-03-01

    Near the central engine, many astrophysical jets are expected to rotate about their axis. Further out they are expected to go through the processes of reconfinement and recollimation. In both these cases, the flow streams along a concave surface and hence, it is subject to the centrifugal force. It is well known that such flows may experience the centrifugal instability (CFI), to which there are many laboratory examples. The recent computer simulations of relativistic jets from active galactic nuclei undergoing the process of reconfinement show that in such jets CFI may dominate over the Kelvin-Helmholtz instability associated with velocity shear (Gourgouliatos & Komissarov). In this letter, we generalize the Rayleigh criterion for CFI in rotating fluids to relativistic flows using a heuristic analysis. We also present the results of computer simulations which support our analytic criterion for the case of an interface separating two uniformly rotating cylindrical flows. We discuss the difference between CFI and the Rayleigh-Taylor instability in flows with curved streamlines.

  15. Analyses of MHD instabilities

    International Nuclear Information System (INIS)

    Takeda, Tatsuoki

    1985-01-01

    In this article analyses of the MHD stabilities which govern the global behavior of a fusion plasma are described from the viewpoint of the numerical computation. First, we describe the high accuracy calculation of the MHD equilibrium and then the analysis of the linear MHD instability. The former is the basis of the stability analysis and the latter is closely related to the limiting beta value which is a very important theoretical issue of the tokamak research. To attain a stable tokamak plasma with good confinement property it is necessary to control or suppress disruptive instabilities. We, next, describe the nonlinear MHD instabilities which relate with the disruption phenomena. Lastly, we describe vectorization of the MHD codes. The above MHD codes for fusion plasma analyses are relatively simple though very time-consuming and parts of the codes which need a lot of CPU time concentrate on a small portion of the codes, moreover, the codes are usually used by the developers of the codes themselves, which make it comparatively easy to attain a high performance ratio on the vector processor. (author)

  16. Ion temperature gradient instability

    International Nuclear Information System (INIS)

    1989-01-01

    Anomalous ion thermal conductivity remains an open physics issue for the present generation of high temperature Tokamaks. It is generally believed to be due to Ion Temperature Gradient Instability (η i mode). However, it has been difficult, if not impossible to identify this instability and study the anomalous transport due to it, directly. Therefore the production and identification of the mode is pursued in the simpler and experimentally convenient configuration of the Columbia Linear Machine (CLM). CLM is a steady state machine which already has all the appropriate parameters, except η i . This parameter is being increased to the appropriate value of the order of 1 by 'feathering' a tungsten screen located between the plasma source and the experimental cell to flatten the density profile and appropriate redesign of heating antennas to steepen the ion temperature profile. Once the instability is produced and identified, a thorough study of the characteristics of the mode can be done via a wide range of variation of all the critical parameters: η i , parallel wavelength, etc

  17. Relation between risk of falling and postural sway complexity in diabetes.

    Science.gov (United States)

    Morrison, S; Colberg, S R; Parson, H K; Vinik, A I

    2012-04-01

    For older individuals with diabetes, any decline in balance control can be especially problematic since it is often a precursor to an increased risk of falling. This study was designed to evaluate differences in postural motion dynamics and falls risk for older individuals with type 2 diabetes (T2DM) classified as fallers/non-fallers and, to assess what impact exercise has on balance and falls risk. The results demonstrated that the risk of falling is greater for those older individuals with multiple risk factors including diabetes and a previous falls history. The postural motion features of the high-risk individuals (T2DM-fallers) were also different, being characterized by increased variability and complexity, increased AP-ML coupling, less overall COP motion and increased velocity. One suggestion is that these individuals evoked a stiffening strategy during the more challenging postural tasks. Following training, a decline in falls risk was observed for all groups, with this effect being most pronounced for the T2DM-fallers. Interestingly, the COP motion of this group became more similar to controls, exhibiting decreased complexity and variability, and decreased velocity. The reciprocal changes in COP complexity support the broader view that age/disease-related changes in physiological complexity are bi-directional. Overall, these results show that, even for older T2DM individuals at greater risk of falling, targeted interventions can positively enhance their postural dynamics. Further, the finding that the pattern of postural motion variability and complexity was altered highlights that a decline in physiological complexity may not always be negatively associated with aging and/or disease. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Yoga Training Has Positive Effects on Postural Balance and Its Influence on Activities of Daily Living in People with Multiple Sclerosis: A Pilot Study.

    Science.gov (United States)

    de Oliveira, Gerson; Tavares, Maria da Consolação Cunha Gomes Fernandes; de Faria Oliveira, Jane Domingues; Rodrigues, Marcos Rojo; Santaella, Danilo Forghieri

    2016-01-01

    There is a little evidence about the influence of yoga as a complementary therapy for postural balance and its influence on activities of daily living in multiple sclerosis (MS) patients. To evaluate the influence of a six-month yoga program on postural balance and subjective impact of postural balance impairment on activities of daily living in people with MS. Randomized controlled pilot study. Protocol developed at the Adaptive Physical Activity Study Department, College of Physical Education, State University of Campinas, Brazil. A total of 12 (11 women) yoga naive people with MS randomly divided into two groups as follows: Control (C-waiting list, n = 6) and Yoga (Y-Yoga training, n = 6). Yoga group practiced postures, breathing exercises, meditation, and relaxation on weekly 60-min classes for a six-month period. The following evaluations were performed at study entry (baseline), and after six months (six months): Berg Balance Scale (BBS), Expanded Disability Status Scale (EDSS), and self-reported postural balance quality and influence of postural balance on activities of daily living. There was a significant improvement in BBS score from baseline to six months only in the Yoga group, especially in subjects with higher EDSS score, with increased quality of self-reported postural balance, and decreased influence of postural balance impairment on activities of daily living. In conclusion, a six-month yoga training is beneficial for people with MS, since it improves postural balance and decreases the influence of postural balance impairment on activities of daily living. A greater sample size is necessary to increase generalization, but it seems that yoga could be included as a feasible complementary therapy for people with MS. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Evaluation of postural stability of people with Parkinson's disease with Biodex Balance System device

    Directory of Open Access Journals (Sweden)

    Jacek Wilczyński

    2016-10-01

    Summary Parkinson's disease is an incurable disease of the CNS of progressive and chronic course. Postural Stability of people with Parkinson's is hindered what predisposes to falls. In a person standing seemingly motionless body performs small oscillatory movements caused by differences in antigravity muscle tension. This mechanism is called postural rocking and mobility associated with it is referred to as postural sway. The parameters of rocking are very sensitive indicator of balance control, and can be used to evaluate and detect pathological changes. The aim of the study was to evaluate the stability of posture of people with Parkinson's disease on the basis of posturographic examination.The age range of the patients was from 52 to 85 years (mean 71.8 years. In terms of age the patients were divided into two groups. The first group consisted of 9 people to 75 years old, while the other of 8 people over 75 years old. The postural stability was assessed with Biodex Balance System. The study was performed at the Laboratory of Posturology at the Institute of Physiotherapy at UJK in Kielce. Although Mann-Whitney U test showed no significant differences in postural stability between the sexes, its lower values are reported for men. A standing position of the subjects was characterized by greater deviation in the sagittal plane than in the frontal plane (A/P>M/L with a tendency to tilt backwards. There were better postural stability results in the younger group (group 1, up to 75 years old. The subjects in this group obtained significantly lower values of postural stability (t°=2.2744, pM/L z tendencją do odchylania się do tyłu. Zaobserwowano lepsze wyniki stabilności posturalnej w grupie osób młodszych (grupa 1 do 75 roku życia. Badani tej grupy uzyskali istotnie niższe wartości stabilności posturalnej (t°= 2,2744, p<0,05.   Słowa kluczowe: stabilność posturalna, choroba Parkinsona, platforma Biodex Balance System

  20. Carrying shopping bags does not alter static postural stability and gait parameters in healthy older females.

    Science.gov (United States)

    Bampouras, Theodoros M; Dewhurst, Susan

    2016-05-01

    Food shopping is an important aspect of maintaining independence and social interaction in older age. Carriage of shopping bags alters the body's weight distribution which, depending on load distribution, could potentially increase instability during standing and walking. The study examined the effect of carrying UK style shopping bags on static postural stability and gait in healthy older and young females. Nine older (71.0±6.0 years) and 10 young (26.7±5.2 years) females were assessed in five conditions carrying no bags, one 1.5kg bag in each hand, one 3kg bag in each hand, one 1.5kg bag in preferred hand, one 3kg bag in preferred hand. Antero-posterior and medio-lateral displacement, and 95% ellipse area from a 30s quiet standing were used for postural stability assessment. Stride length and its coefficient of variation, total double support time, step asymmetry and gait stability ratio were calculated from 1min treadmill walking at self-selected speed for gait assessment. Carrying shopping bags did not negatively affect postural stability or gait variables, in either group. Further, in older individuals, a decrease in sway velocity was found when holding bags during the postural stability assessment (pbags, irrespective of the load distribution, may have a stabilising effect during quiet standing. These results should help to alleviate concerns regarding safety of carrying shopping bags and help encourage shopping, both as a social and as a physical activity. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. The Effect of Visual Stimuli on Stability and Complexity of Postural Control

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    Haizhen Luo

    2018-02-01

    Full Text Available Visual input could benefit balance control or increase postural sway, and it is far from fully understanding the effect of visual stimuli on postural stability and its underlying mechanism. In this study, the effect of different visual inputs on stability and complexity of postural control was examined by analyzing the mean velocity (MV, SD, and fuzzy approximate entropy (fApEn of the center of pressure (COP signal during quiet upright standing. We designed five visual exposure conditions: eyes-closed, eyes-open (EO, and three virtual reality (VR scenes (VR1–VR3. The VR scenes were a limited field view of an optokinetic drum rotating around yaw (VR1, pitch (VR2, and roll (VR3 axes, respectively. Sixteen healthy subjects were involved in the experiment, and their COP trajectories were assessed from the force plate data. MV, SD, and fApEn of the COP in anterior–posterior (AP, medial–lateral (ML directions were calculated. Two-way analysis of variance with repeated measures was conducted to test the statistical significance. We found that all the three parameters obtained the lowest values in the EO condition, and highest in the VR3 condition. We also found that the active neuromuscular intervention, indicated by fApEn, in response to changing the visual exposure conditions were more adaptive in AP direction, and the stability, indicated by SD, in ML direction reflected the changes of visual scenes. MV was found to capture both instability and active neuromuscular control dynamics. It seemed that the three parameters provided compensatory information about the postural control in the immersive virtual environment.

  2. 2012 National Guard Bureau Posture Statement

    Science.gov (United States)

    2012-01-01

    Illinois / Poland Indiana / Slovakia Kansas / Armenia Maine/ Montenegro Maryland / Estonia Maryland / Bosnia Michigan / Latvia Minnesota / Croatia New Jersey...alternative methods of planting to help increase crop production in the area. 2012 Posture Statement 19 Global Engagement State Partnership...horticulture ( plant cultivation), pest control, veterinary/animal husbandry techniques, civil engineering, and energy management. As a result of the

  3. Postural Determinants in the Blind. Final Report.

    Science.gov (United States)

    Siegel, Irwin M.; Murphy, Thomas J.

    The problem of malposture in the blind and its affect on orientation and travel skills was explored. A group of 45 students were enrolled in a standard 3-month mobility training program. Each student suffered a postural problem, some compounded by severe orthopedic and/or neurological deficit. All subjects were given complete orthopedic and…

  4. Smart rehabilitation garment for posture monitoring

    NARCIS (Netherlands)

    Wang, Q.; Chen, W.; Timmermans, A.A.A.; Karachristos, C.; Martens, J.B.O.S.; Markopoulos, P.

    Posture monitoring and correction technologies can support prevention and treatment of spinal pain or can help detect and avoid compensatory movements during the neurological rehabilitation of upper extremities, which can be very important to ensure their effectiveness. We describe the design and

  5. Robust balance shift control with posture optimization

    NARCIS (Netherlands)

    Kavafoglu, Z.; Kavafoglu, Ersan; Egges, J.

    2015-01-01

    In this paper we present a control framework which creates robust and natural balance shifting behaviours during standing. Given high-level features such as the position of the center of mass projection and the foot configurations, a kinematic posture satisfying these features is synthesized using

  6. Can smartwatches replace smartphones for posture tracking?

    Science.gov (United States)

    Mortazavi, Bobak; Nemati, Ebrahim; VanderWall, Kristina; Flores-Rodriguez, Hector G; Cai, Jun Yu Jacinta; Lucier, Jessica; Naeim, Arash; Sarrafzadeh, Majid

    2015-10-22

    This paper introduces a human posture tracking platform to identify the human postures of sitting, standing or lying down, based on a smartwatch. This work develops such a system as a proof-of-concept study to investigate a smartwatch's ability to be used in future remote health monitoring systems and applications. This work validates the smartwatches' ability to track the posture of users accurately in a laboratory setting while reducing the sampling rate to potentially improve battery life, the first steps in verifying that such a system would work in future clinical settings. The algorithm developed classifies the transitions between three posture states of sitting, standing and lying down, by identifying these transition movements, as well as other movements that might be mistaken for these transitions. The system is trained and developed on a Samsung Galaxy Gear smartwatch, and the algorithm was validated through a leave-one-subject-out cross-validation of 20 subjects. The system can identify the appropriate transitions at only 10 Hz with an F-score of 0.930, indicating its ability to effectively replace smart phones, if needed.

  7. Public and Private Posture : Zadie Smith

    NARCIS (Netherlands)

    Heynders, Odile

    2016-01-01

    This chapter will focus on Smith’s posture, and in particular on how her public position and literary work negotiate issues such as identification, celebrity, style and authenticity. First, the paradox of the ‘celebrity authority’ will be examined, followed by a Derrida-inspired analysis of Smith’s

  8. Evaluation of body posture in nursing students

    Directory of Open Access Journals (Sweden)

    Marília Fernandes Andrade

    2017-08-01

    Full Text Available Abstract OBJECTIVE To investigate the body posture of nursing students before and after clinical practice. METHOD The study was developed in two stages. Initially the body posture of students of the 2nd, 4th, 6th, and 8th periods were assessed through photogrammetry. All images were analyzed in a random and masked manner with CorporisPro® 3.1.3 software. Three evaluations were performed for each angle and then the mean value was calculated. Two years later, when the 4th period students had developed their clinical internships, their body posture was again evaluated. RESULTS The total sample consisted of 112 students. Comparison of their posture with the normality pattern showed that all the angles presented significant differences (p< 0.00, except for the angle of the Thales triangle. Reassessment of these students evidenced significant differences in the angles of the acromioclavicular joint (p=0.03, knee flexion (p< 0.00 and in the tibiotarsal angle (p< 0.00. CONCLUSION All the students presented alterations when compared to the normality values. The segments that presented significant differences between before and after practice were the acromioclavicular angle, knee flexion, and tibiotarsal angle; the latter two were in the rolling position.

  9. 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).

  10. Posture changes and subfoveal choroidal blood flow.

    Science.gov (United States)

    Longo, Antonio; Geiser, Martial H; Riva, Charles E

    2004-02-01

    To evaluate the effect of posture change on subfoveal choroidal blood flow (ChBF) in normal volunteers. The pulsatile, nonpulsatile, and mean ChBF were measured with laser Doppler flowmetry in 11 healthy volunteers with a mean age of 32 +/- 13 (SD) years. The posture of the subjects was changed from standing (90 degrees ), to supine (-8 degrees ), and back to standing, with a mechanically driven table. During the whole experimental procedure, ChBF and heart rate (HR) were continuously recorded. After 30 seconds in standing position, the subjects were tilted to supine during approximately 30 seconds. They remained in this position for approximately 2 minutes, after which they were tilted back to the standing position (recovery), where they remained for another approximately 2 minutes. Systemic brachial artery blood pressure (BP) was measured in the baseline, supine, and recovery positions. This procedure was repeated to measure the intraocular pressure (IOP) at the different postures. Mean BP did not change significantly throughout the experimental procedure. As the body was tilted from standing to supine, HR decreased by 16% (P blood velocity. Based on previously reported experimental data that indicate that the ocular perfusion pressure increases less than predicted by purely hydrostatic considerations when the body is tilted from the standing to the supine position, the observed increase in ChBF suggests a passive response of the choroidal circulation to the posture change.

  11. 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.

  12. 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.

  13. Posture and Texting: Effect on Balance in Young Adults.

    Directory of Open Access Journals (Sweden)

    Nurul Retno Nurwulan

    Full Text Available Using a mobile phone while doing another activity is a common dual-task activity in our daily lives. This study examined the effect of texting on the postural stability of young adults. Twenty college students were asked to perform static and dynamic postural stability tasks. Traditional COP and multivariate multiscale entropy (MMSE were used to assess the static postural stability and the Star Excursion Balance Test (SEBT was used to assess the dynamic postural stability. Results showed that (1 texting impaired postural stability, (2 the complexity index did not change much although the task conditions changed, and (3 performing texting is perceived to be more difficult.

  14. Should Ballet Dancers Vary Postures and Underfoot Surfaces When Practicing Postural Balance?

    Science.gov (United States)

    Steinberg, Nili; Waddington, Gordon; Adams, Roger; Karin, Janet; Tirosh, Oren

    2018-01-01

    Postural balance (PB) is an important component skill for professional dancers. However, the effects of different types of postures and different underfoot surfaces on PB have not adequately been addressed. The main aim of this study was to investigate the effect of different conditions of footwear, surfaces, and standing positions on static and dynamic PB ability of young ballet dancers. A total of 36 male and female young professional ballet dancers (aged 14-19 years) completed static and dynamic balance testing, measured by head and lumbar accelerometers, while standing on one leg in the turnout position, under six different conditions: (1) "relaxed" posture; (2) "ballet" posture; (3) barefoot; (4) ballet shoes with textured insoles; (5) barefoot on a textured mat; and (6) barefoot on a spiky mat. A condition effect was found for static and dynamic PB. Static PB was reduced when dancers stood in the ballet posture compared with standing in the relaxed posture and when standing on a textured mat and on a spiky mat (p ballet shoes with textured insoles and when standing on a spiky mat compared with all other conditions (p ballet aligned position, including dance practice on different types of floors and on different types of textured/spiky materials may result in skill transfer to practice on normal floor surfaces, and both static and dynamic PB exercises should be assessed and generalized into practical dance routines.

  15. Chronic Ankle Instability and Neural Excitability of the Lower Extremity.

    Science.gov (United States)

    McLeod, Michelle M; Gribble, Phillip A; Pietrosimone, Brian G

    2015-08-01

    Neuromuscular dysfunction of the leg and thigh musculature, including decreased strength and postural control, is common in patients with chronic ankle instability (CAI). Understanding how CAI affects specific neural pathways may provide valuable information for targeted therapies. To investigate differences in spinal reflexive and corticospinal excitability of the fibularis longus and vastus medialis between limbs in patients with unilateral CAI and between CAI patients and participants serving as healthy controls. Case-control study. Research laboratory. A total of 56 participants volunteered, and complete data for 21 CAI patients (9 men, 12 women; age = 20.81 ± 1.63 years, height = 171.57 ± 11.44 cm, mass = 68.84 ± 11.93 kg) and 24 healthy participants serving as controls (7 men, 17 women; age = 22.54 ± 2.92 years, height = 172.35 ± 10.85 cm, mass = 69.15 ± 12.30 kg) were included in the final analyses. Control participants were matched to CAI patients on sex, age, and limb dominance. We assigned "involved" limbs, which corresponded with the involved limbs of the CAI patients, to control participants. Spinal reflexive excitability was assessed via the Hoffmann reflex and normalized to a maximal muscle response. Corticospinal excitability was assessed using transcranial magnetic stimulation. Active motor threshold (AMT) was defined as the lowest transcranial magnetic stimulation intensity required to elicit motor-evoked potentials equal to or greater than 100 μV in 5 of 10 consecutive stimuli. We obtained motor-evoked potentials (MEPs) at percentages ranging from 100% to 140% of AMT. Fibularis longus MEP amplitudes were greater in control participants than in CAI patients bilaterally at 100% AMT (control involved limb: 0.023 ± 0.031; CAI involved limb: 0.014 ± 0.008; control uninvolved limb: 0.021 ± 0.022; CAI uninvolved limb: 0.015 ± 0.007; F1,41 = 4.551, P = .04) and 105% AMT (control involved limb: 0.029 ± 0.026; CAI involved limb: 0.021 ± 0

  16. Postural control in women with breast hypertrophy

    Directory of Open Access Journals (Sweden)

    Alessandra Ferreira Barbosa

    2012-07-01

    Full Text Available OBJECTIVES: The consequences of breast hypertrophy have been described based on the alteration of body mass distribution, leading to an impact on psychological and physical aspects. The principles of motor control suggest that breast hypertrophy can lead to sensorimotor alterations and the impairment of body balance due to postural misalignment. The aim of this study is to evaluate the postural control of women with breast hypertrophy under different sensory information conditions. METHOD: This cross-sectional study included 14 women with breast hypertrophy and 14 without breast hypertrophy, and the mean ages of the groups were 39 ±15 years and 39±16 years, respectively. A force platform was used to assess the sensory systems that contribute to postural control: somatosensory, visual and vestibular. Four postural conditions were sequentially tested: eyes open and fixed platform, eyes closed and fixed platform, eyes open and mobile platform, and eyes closed and mobile platform. The data were processed, and variables related to the center of pressure were analyzed for each condition. The Kruskal-Wallis test was used to compare the conditions between the groups for the area of center of pressure displacement and the velocity of center of pressure displacement in the anterior-posterior and medial-lateral directions. The alpha level error was set at 0.05. RESULTS: Women with breast hypertrophy presented an area that was significantly higher for three out of four conditions and a higher velocity of center of pressure displacement in the anterior-posterior direction under two conditions: eyes open and mobile platform and eyes closed and mobile platform. CONCLUSIONS: Women with breast hypertrophy have altered postural control, which was demonstrated by the higher area and velocity of center of pressure displacement.

  17. A new methodology based on functional principal component analysis to study postural stability post-stroke.

    Science.gov (United States)

    Sánchez-Sánchez, M Luz; Belda-Lois, Juan-Manuel; Mena-Del Horno, Silvia; Viosca-Herrero, Enrique; Igual-Camacho, Celedonia; Gisbert-Morant, Beatriz

    2018-05-05

    A major goal in stroke rehabilitation is the establishment of more effective physical therapy techniques to recover postural stability. Functional Principal Component Analysis provides greater insight into recovery trends. However, when missing values exist, obtaining functional data presents some difficulties. The purpose of this study was to reveal an alternative technique for obtaining the Functional Principal Components without requiring the conversion to functional data beforehand and to investigate this methodology to determine the effect of specific physical therapy techniques in balance recovery trends in elderly subjects with hemiplegia post-stroke. A randomized controlled pilot trial was developed. Thirty inpatients post-stroke were included. Control and target groups were treated with the same conventional physical therapy protocol based on functional criteria, but specific techniques were added to the target group depending on the subjects' functional level. Postural stability during standing was quantified by posturography. The assessments were performed once a month from the moment the participants were able to stand up to six months post-stroke. The target group showed a significant improvement in postural control recovery trend six months after stroke that was not present in the control group. Some of the assessed parameters revealed significant differences between treatment groups (P Functional Principal Component Analysis to be performed when data is scarce. Moreover, it allowed the dynamics of recovery of two different treatment groups to be determined, showing that the techniques added in the target group increased postural stability compared to the base protocol. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs

    Directory of Open Access Journals (Sweden)

    Michael P. Taylor

    2014-12-01

    Full Text Available Attempts to reconstruct the neutral neck posture of sauropod dinosaurs, or indeed any tetrapod, are doomed to failure when based only on the geometry of the bony cervical vertebrae. The thickness of the articular cartilage between the centra of adjacent vertebrae affects posture. It extends (raises the neck by an amount roughly proportional to the thickness of the cartilage. It is possible to quantify the angle of extension at an intervertebral joint: it is roughly equal, in radians, to the cartilage thickness divided by the height of the zygapophyseal facets over the centre of rotation. Applying this formula to published measurements of well-known sauropod specimens suggests that if the thickness of cartilage were equal to 4.5%, 10% or 18% of centrum length, the neutral pose of the Apatosaurus louisae holotype CM 3018 would be extended by an average of 5.5, 11.8 or 21.2 degrees, respectively, at each intervertebral joint. For the Diplodocus carnegii holotype CM 84, the corresponding angles of additional extension are even greater: 8.4, 18.6 or 33.3 degrees. The cartilaginous neutral postures (CNPs calculated for 10% cartilage—the most reasonable estimate—appear outlandish. But it must be remembered that these would not have been the habitual life postures, because tetrapods habitually extend the base of their neck and flex the anterior part, yielding the distinctive S-curve most easily seen in birds.

  19. Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs.

    Science.gov (United States)

    Taylor, Michael P

    2014-01-01

    Attempts to reconstruct the neutral neck posture of sauropod dinosaurs, or indeed any tetrapod, are doomed to failure when based only on the geometry of the bony cervical vertebrae. The thickness of the articular cartilage between the centra of adjacent vertebrae affects posture. It extends (raises) the neck by an amount roughly proportional to the thickness of the cartilage. It is possible to quantify the angle of extension at an intervertebral joint: it is roughly equal, in radians, to the cartilage thickness divided by the height of the zygapophyseal facets over the centre of rotation. Applying this formula to published measurements of well-known sauropod specimens suggests that if the thickness of cartilage were equal to 4.5%, 10% or 18% of centrum length, the neutral pose of the Apatosaurus louisae holotype CM 3018 would be extended by an average of 5.5, 11.8 or 21.2 degrees, respectively, at each intervertebral joint. For the Diplodocus carnegii holotype CM 84, the corresponding angles of additional extension are even greater: 8.4, 18.6 or 33.3 degrees. The cartilaginous neutral postures (CNPs) calculated for 10% cartilage-the most reasonable estimate-appear outlandish. But it must be remembered that these would not have been the habitual life postures, because tetrapods habitually extend the base of their neck and flex the anterior part, yielding the distinctive S-curve most easily seen in birds.

  20. Embodied prosthetic arm stabilizes body posture, while unembodied one perturbs it.

    Science.gov (United States)

    Imaizumi, Shu; Asai, Tomohisa; Koyama, Shinichi

    2016-10-01

    Senses of ownership (this arm belongs to me) and agency (I am controlling this arm) originate from sensorimotor system. External objects can be integrated into the sensorimotor system following long-term use, and recognized as one's own body. We examined how an (un)embodied prosthetic arm modulates whole-body control, and assessed the components of prosthetic embodiment. Nine unilateral upper-limb amputees participated. Four frequently used their prosthetic arm, while the others rarely did. Their postural sway was measured during quiet standing with or without their prosthesis. The frequent users showed greater sway when they removed the prosthesis, while the rare users showed greater sway when they fitted the prosthesis. Frequent users reported greater everyday feelings of postural stabilization by prosthesis and a larger sense of agency over the prosthesis. We suggest that a prosthetic arm maintains or perturbs postural control, depending on the prosthetic embodiment, which involves sense of agency rather than ownership. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Instability of warped discs

    Science.gov (United States)

    Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.

    2018-05-01

    Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further, if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which, in general, yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term that would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ < 0) but is here modified by the warp to include ∂(ν1|ψ|)/∂|ψ| < 0, and (2) a similar condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.

  2. System Detects Vibrational Instabilities

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1990-01-01

    Sustained vibrations at two critical frequencies trigger diagnostic response or shutdown. Vibration-analyzing electronic system detects instabilities of combustion in rocket engine. Controls pulse-mode firing of engine and identifies vibrations above threshold amplitude at 5.9 and/or 12kHz. Adapted to other detection and/or control schemes involving simultaneous real-time detection of signals above or below preset amplitudes at two or more specified frequencies. Potential applications include rotating machinery and encoders and decoders in security systems.

  3. Evaporation and Antievaporation Instabilities

    Directory of Open Access Journals (Sweden)

    Andrea Addazi

    2017-10-01

    Full Text Available We review (antievaporation phenomena within the context of quantum gravity and extended theories of gravity. The (antievaporation effect is an instability of the black hole horizon discovered in many different scenarios: quantum dilaton-gravity, f ( R -gravity, f ( T -gravity, string-inspired black holes, and brane-world cosmology. Evaporating and antievaporating black holes seem to have completely different thermodynamical features compared to standard semiclassical black holes. The purpose of this review is to provide an introduction to conceptual and technical aspects of (antievaporation effects, while discussing problems that are still open.

  4. The reliability and validity of the Saliba Postural Classification System.

    Science.gov (United States)

    Collins, Cristiana Kahl; Johnson, Vicky Saliba; Godwin, Ellen M; Pappas, Evangelos

    2016-07-01

    To determine the reliability and validity of the Saliba Postural Classification System (SPCS). Two physical therapists classified pictures of 100 volunteer participants standing in their habitual posture for inter and intra-tester reliability. For validity, 54 participants stood on a force plate in a habitual and a corrected posture, while a vertical force was applied through the shoulders until the clinician felt a postural give. Data were extracted at the time the give was felt and at a time in the corrected posture that matched the peak vertical ground reaction force (VGRF) in the habitual posture. Inter-tester reliability demonstrated 75% agreement with a Kappa = 0.64 (95% CI = 0.524-0.756, SE = 0.059). Intra-tester reliability demonstrated 87% agreement with a Kappa = 0.8, (95% CI = 0.702-0.898, SE = 0.05) and 80% agreement with a Kappa = 0.706, (95% CI = 0.594-0818, SE = 0.057). The examiner applied a significantly higher (p < 0.001) peak vertical force in the corrected posture prior to a postural give when compared to the habitual posture. Within the corrected posture, the %VGRF was higher when the test was ongoing vs. when a postural give was felt (p < 0.001). The %VGRF was not different between the two postures when comparing the peaks (p = 0.214). The SPCS has substantial agreement for inter- and intra-tester reliability and is largely a valid postural classification system as determined by the larger vertical forces in the corrected postures. Further studies on the correlation between the SPCS and diagnostic classifications are indicated.

  5. Resonant Drag Instabilities in protoplanetary disks: the streaming instability and new, faster-growing instabilities

    Science.gov (United States)

    Squire, Jonathan; Hopkins, Philip F.

    2018-04-01

    We identify and study a number of new, rapidly growing instabilities of dust grains in protoplanetary disks, which may be important for planetesimal formation. The study is based on the recognition that dust-gas mixtures are generically unstable to a Resonant Drag Instability (RDI), whenever the gas, absent dust, supports undamped linear modes. We show that the "streaming instability" is an RDI associated with epicyclic oscillations; this provides simple interpretations for its mechanisms and accurate analytic expressions for its growth rates and fastest-growing wavelengths. We extend this analysis to more general dust streaming motions and other waves, including buoyancy and magnetohydrodynamic oscillations, finding various new instabilities. Most importantly, we identify the disk "settling instability," which occurs as dust settles vertically into the midplane of a rotating disk. For small grains, this instability grows many orders of magnitude faster than the standard streaming instability, with a growth rate that is independent of grain size. Growth timescales for realistic dust-to-gas ratios are comparable to the disk orbital period, and the characteristic wavelengths are more than an order of magnitude larger than the streaming instability (allowing the instability to concentrate larger masses). This suggests that in the process of settling, dust will band into rings then filaments or clumps, potentially seeding dust traps, high-metallicity regions that in turn seed the streaming instability, or even overdensities that coagulate or directly collapse to planetesimals.

  6. The Effect of Balance Training on Postural Control in Patients with Parkinson's Disease Using a Virtual Rehabilitation System.

    Science.gov (United States)

    Albiol-Pérez, Sergio; Gil-Gómez, José-Antonio; Muñoz-Tomás, María-Teresa; Gil-Gómez, Hermenegildo; Vial-Escolano, Raquel; Lozano-Quilis, José-Antonio

    2017-03-23

    Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor clinical alterations among others. Postural problems have serious consequences for patients, not only limiting their daily life but also increasing some risks, like the risk of fall. Inadequate postural control and postural instability is a major problem in PD patients. A Virtual Motor Rehabilitation System (VMR) has been tested in patients with PD in the intervention period. Our purpose was to analyze the evolution of the spatial postural control during the intervention period, to see if there are any changes caused precisely by this intervention. Ten people with PD carried out 15 virtual rehabilitation sessions. We tested a groundbreaking system based on Virtual Motor Rehabilitation in two periods of time (baseline evaluation and final evaluation). In the training sessions, the participants performed a customizable treatment using a low-cost system, the Active Balance Rehabilitation system (ABAR). We stored the pressure performed by the participants every five hundredths of a second, and we analyzed the patients' pressure when they maintained their body on the left, on the right, and in the center in sitting position. Our system was able to measure postural control in every patient in each of the virtual rehabilitation sessions. There are no significant differences in the performance of postural control in any of the positions evaluated throughout the sessions. Moreover, the results show a trend to an improvement in all positions. This improvement is especially remarkable in the left/right positions, which are the most important positions in order to avoid problems such as the risk of fall. With regard to the suitability of the ABAR system, we have found outstanding results in enjoyment, success, clarity, and helpfulness. Although PD is a progressive neurodegenerative disorder, the results demonstrate that patients with PD maintain or even improve their postural control

  7. Relationship between Muscle Function, Muscle Typology and Postural Performance According to Different Postural Conditions in Young and Older Adults.

    Science.gov (United States)

    Paillard, Thierry

    2017-01-01

    Although motor output of the postural function clearly influences postural performance in young and older subjects, no relationship has been formally established between them. However, the relationship between lower-extremity muscle strength/power and postural performance is often pointed out, especially in older subjects. In fact, the influence of motor output may vary according to the postural condition considered (e.g., static, dynamic, challenging, disturbing). In static postural condition, there may be a relationship between lower-extremity muscle strength and postural performance when the value of muscle strength is below a certain threshold in older subjects. Above this threshold of muscle strength, this relationship may disappear. In dynamic postural condition, lower-extremity muscle power could facilitate compensatory postural actions, limiting induced body imbalance likely to generate falls in older subjects. In young subjects, there could be a relationship between very early rapid torque of the leg extensor muscles and postural performance. In the case of postural reaction to (external) perturbations, a high percentage of type II muscle fibers could be associated with the ability to react quickly to postural perturbations in young subjects, while it may enable a reduction in the risk of falls in older subjects. In practice, in older subjects, muscle strength and/or power training contributes to reducing the risk of falls, as well as slowing down the involution of muscle typology regarding type II muscle fibers.

  8. Feedback stabilization of plasma instabilities

    International Nuclear Information System (INIS)

    Cap, F.F.

    1977-01-01

    This paper reviews the theoretical and experimental aspects of feedback stabilization. After giving an outline of a general theoretical model for electrostatic instabilities the author provides a theoretical analysis of the suppression of various types of instability. Experiments which have been carried out on the feedback stabilization of various types of plasma instability are reported. An extensive list of references is given. (B.R.H.)

  9. Thermal Shrinkage for Shoulder Instability

    OpenAIRE

    Toth, Alison P.; Warren, Russell F.; Petrigliano, Frank A.; Doward, David A.; Cordasco, Frank A.; Altchek, David W.; O’Brien, Stephen J.

    2010-01-01

    Thermal capsular shrinkage was popular for the treatment of shoulder instability, despite a paucity of outcomes data in the literature defining the indications for this procedure or supporting its long-term efficacy. The purpose of this study was to perform a clinical evaluation of radiofrequency thermal capsular shrinkage for the treatment of shoulder instability, with a minimum 2-year follow-up. From 1999 to 2001, 101 consecutive patients with mild to moderate shoulder instability underwent...

  10. Political Instability and Economic Growth

    OpenAIRE

    Alberto Alesina; Sule Ozler; Nouriel Roubini; Phillip Swagel

    1992-01-01

    This paper investigates the relationship between political instability and per capita GDP growth in a sample of 113 countries for the period 1950-1982. We define ?political instability? as the propensity of a government collapse, and we estimate a model in which political instability and economic growth are jointly determined. The main result of this paper is that in countries and time periods with a high propensity of government collapse, growth is significantly lower than otherwise. This ef...

  11. Instabilities in mimetic matter perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Firouzjahi, Hassan; Gorji, Mohammad Ali [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Mansoori, Seyed Ali Hosseini, E-mail: firouz@ipm.ir, E-mail: gorji@ipm.ir, E-mail: shosseini@shahroodut.ac.ir, E-mail: shossein@ipm.ir [Physics Department, Shahrood University of Technology, P.O. Box 3619995161 Shahrood (Iran, Islamic Republic of)

    2017-07-01

    We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.

  12. Neural substrates of interpreting actions and emotions from body postures.

    Science.gov (United States)

    Kana, Rajesh K; Travers, Brittany G

    2012-04-01

    Accurately reading the body language of others may be vital for navigating the social world, and this ability may be influenced by factors, such as our gender, personality characteristics and neurocognitive processes. This fMRI study examined the brain activation of 26 healthy individuals (14 women and 12 men) while they judged the action performed or the emotion felt by stick figure characters appearing in different postures. In both tasks, participants activated areas associated with visual representation of the body, motion processing and emotion recognition. Behaviorally, participants demonstrated greater ease in judging the physical actions of the characters compared to judging their emotional states, and participants showed more activation in areas associated with emotion processing in the emotion detection task, whereas they showed more activation in visual, spatial and action-related areas in the physical action task. Gender differences emerged in brain responses, such that men showed greater activation than women in the left dorsal premotor cortex in both tasks. Finally, participants higher in self-reported empathy demonstrated greater activation in areas associated with self-referential processing and emotion interpretation. These results suggest that empathy levels and sex of the participant may affect neural responses to emotional body language.

  13. Somatic features and body posture in children with scoliosis and scoliotic posture

    Directory of Open Access Journals (Sweden)

    Jacek Wilczyński

    2017-08-01

    Full Text Available Abstract The aim of the study was to evaluate the relationship between somatic features and body posture in children with scoliosis and scoliotic posture. The study included 28 girls aged 7-18 with scoliosis and scoliotic posture. The selection of the subjects was deliberate. Height measurements were conducted with an anthropometer and weight measurements were done with an electronic scale. Body posture tests were performed using Exhibeon 3D digital photogrammetry and digital radiographs. The significant Spearman correlations between postural variables for the sagittal plane and the somatic variables regarded: trunk inclination angle and BMI (R= 0,4553, p= p=0,015, Abs of the trunk inclination angle and BMI (R = 0.5522, p = 0.002, length of thoracic kyphosis and BMI (R=0,4147, p=0.028, lumbar lordosis and BMI (R=0,4509, p=0,016. The significant Spearman correlations between scoliotic posture variables and the somatic variables concerned: length of primary lordosis and body height (R =0,4923, p=0.008, the length of the primary lordosis and body mass (R = 0.3932, p = 0.038, the length of the primary lordosis and BMI (R=0,4923, p=0.008. Variation analysis regarding postural (Exhibeon and somatic variables showed significant correlations between the direction of the primary curvature and body mass (p=0,0432, body height and primary angle location (p=0,0290 and between the height of the body and the location of the secondary angle (p = 0,0278.

  14. [Autoerotic fatalities in Greater Dusseldorf].

    Science.gov (United States)

    Hartung, Benno; Hellen, Florence; Borchard, Nora; Huckenbeck, Wolfgang

    2011-01-01

    Autoerotic fatalities in the Greater Dusseldorf area correspond to the relevant medicolegal literature. Our results included exclusively young to middle-aged, usually single men who were found dead in their city apartments. Clothing and devices used showed a great variety. Women's or fetish clothing and complex shackling or hanging devices were disproportionately frequent. In most cases, death occurred due to hanging or ligature strangulation. There was no increased incidence of underlying psychiatric disorders. In most of the deceased no or at least no remarkable alcohol intoxication was found. Occasionally, it may be difficult to reliably differentiate autoerotic accidents, accidents occurring in connection with practices of bondage & discipline, dominance & submission (BDSM) from natural death, suicide or homicide.

  15. Planning for greater confinement disposal

    International Nuclear Information System (INIS)

    Gilbert, T.L.; Luner, C.; Meshkov, N.K.; Trevorrow, L.E.; Yu, C.

    1985-01-01

    A report that provides guidance for planning for greater-confinement disposal (GCD) of low-level radioactive waste is being prepared. The report addresses procedures for selecting a GCD technology and provides information for implementing these procedures. The focus is on GCD; planning aspects common to GCD and shallow-land burial are covered by reference. Planning procedure topics covered include regulatory requirements, waste characterization, benefit-cost-risk assessment and pathway analysis methodologies, determination of need, waste-acceptance criteria, performance objectives, and comparative assessment of attributes that support these objectives. The major technologies covered include augered shafts, deep trenches, engineered structures, hydrofracture, improved waste forms, and high-integrity containers. Descriptive information is provided, and attributes that are relevant for risk assessment and operational requirements are given. 10 refs., 3 figs., 2 tabs

  16. Instability characteristics of fluidelastic instability of tube rows in crossflow

    International Nuclear Information System (INIS)

    Chen, S.S.; Jendrzejczyk, J.A.

    1986-04-01

    An experimental study is reported to investigate the jump phenomenon in critical flow velocities for tube rows with different pitch-to-diameter ratios and the excited and intrinsic instabilities for a tube row with a pitch-to-diameter ratio of 1.75. The experimental data provide additional insights into the instability phenomena of tube arrays in crossflow. 9 refs., 10 figs

  17. Identifying postural control and thresholds of instability utilizing a motion-based ATV simulator.

    Science.gov (United States)

    2017-01-01

    Our ATV simulator is currently the only one in existence that allows studies of human subjects engaged in active riding, a process that is necessary for ATV operators to perform in order to maintain vehicle control, in a virtual reality environ...

  18. Misclassification of Patients with Spinocerebellar Ataxia as having Psychogenic Postural Instability based on Computerized Dynamic Posturography

    Directory of Open Access Journals (Sweden)

    Susan J Herdman

    2011-04-01

    Full Text Available Specific criteria have been developed based on computerized dynamic posturography (CDP to assist clinicians in identifying patients with psychogenic balance problems1-4. Patients with known Spinocerebellar Ataxia (SCA meet several of the criteria for psychogenic balance problem and risk being misclassified as having imbalance of psychogenic origin. However, our research shows that patients with SCA may be distinguished from patients with psychogenic balance problems in several ways. We compared test performance on CDP and the observation of specific behaviors that are associated with psychogenic balance problems in patients with SCA (n = 43 and patients with known psychogenic balance problems (n = 40. Chi square analysis was used to determine if there were significant differences between the groups for the frequency of each criterion for psychogenic CDP and Observed Behaviors. Level of significance was Bonferroni corrected for multiple comparisons. Sensitivity, specificity, and positive likelihood ratios were calculated for each criterion. Hierarchical cluster analysis was used to examine whether the two patient groups demonstrated similar groupings of criteria. Comparison of the results of these analyses identified two criteria that were significantly more frequent in the Psychogenic group than in the SCA group: Regular Periodicity of sway and Circular Sway. Sensitivity, specificity and positive likelihood ratios identified two additional criteria, Inconsistent Motor Responses and Large lateral Sway that also seem to suggest a psychogenic component to a person’s imbalance. Prospective studies are needed to validate the usefulness of these findings.

  19. Ergonomic strategies to improve radiographers' posture during mammography activities.

    Science.gov (United States)

    Cernean, Nicolai; Serranheira, Florentino; Gonçalves, Pedro; Sá Dos Reis, Cláudia

    2017-08-01

    To identify alternatives for radiographers' postures while performing mammography that can contribute to reduce the risk of work-related musculoskeletal disorders (WRMSDs). Radiographers' postures to positioning craniocaudal (CC) and mediolateral oblique (MLO) views were simulated without any intervention for three scenarios: radiographer/patient with similar statures, radiographer smaller than patient and radiographer taller than patient. Actions were taken to modify the postures: seated radiographer; patient on a step; seated patient; radiographer on a step. All the postures were analysed using kinovea 0.8.15 software and the angles were measured twice and classified according to European standard EN1005-4: 2005. The non-acceptable angles were measured mainly during MLO positioning when radiographer was taller than the patient: 139° and 120° for arm-flexion and abduction, 72° for trunk and -24° for head/neck-flexion. The introduction of alternative postures (radiographer seated), allowed improvements in posture (60° and 99° for arm flexion and abduction, 14° for trunk and 0° for head/neck flexion), being classified as acceptable. The alternative postures simulated have the potential to reduce the risk of developing WRMSDs when radiographers and patients have different statures. • Radiographers' postures in mammography can contribute to work-related musculoskeletal disorders • Non-acceptable posture was identified for MLO breast positioning (radiographer taller than patient) • Adapting posture to patient biotype reduces the WRMSD risk for radiographers.

  20. Obesity impact on the attentional cost for controlling posture.

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Mignardot

    2010-12-01

    Full Text Available This study investigated the effects of obesity on attentional resources allocated to postural control in seating and unipedal standing.Ten non obese adults (BMI = 22.4±1.3, age = 42.4±15.1 and 10 obese adult patients (BMI = 35.2±2.8, age = 46.2±19.6 maintained postural stability on a force platform in two postural tasks (seated and unipedal. The two postural tasks were performed (1 alone and (2 in a dual-task paradigm in combination with an auditory reaction time task (RT. Performing the RT task together with the postural one was supposed to require some attentional resources that allowed estimating the attentional cost of postural control. 4 trials were performed in each condition for a total of 16 trials.(1 Whereas seated non obese and obese patients exhibited similar centre of foot pressure oscillations (CoP, in the unipedal stance only obese patients strongly increased their CoP sway in comparison to controls. (2 Whatever the postural task, the additional RT task did not affect postural stability. (3 Seated, RT did not differ between the two groups. (4 RT strongly increased between the two postural conditions in the obese patients only, suggesting that body schema and the use of internal models was altered with obesity.Obese patients needed more attentional resources to control postural stability during unipedal stance than non obese participants. This was not the case in a more simple posture such as seating. To reduce the risk of fall as indicated by the critical values of CoP displacement, obese patients must dedicate a strong large part of their attentional resources to postural control, to the detriment of non-postural events. Obese patients were not able to easily perform multitasking as healthy adults do, reflecting weakened psycho-motor abilities.

  1. Obesity Impact on the Attentional Cost for Controlling Posture

    Science.gov (United States)

    Mignardot, Jean-Baptiste; Olivier, Isabelle; Promayon, Emmanuel; Nougier, Vincent

    2010-01-01

    Background This study investigated the effects of obesity on attentional resources allocated to postural control in seating and unipedal standing. Methods Ten non obese adults (BMI = 22.4±1.3, age = 42.4±15.1) and 10 obese adult patients (BMI = 35.2±2.8, age = 46.2±19.6) maintained postural stability on a force platform in two postural tasks (seated and unipedal). The two postural tasks were performed (1) alone and (2) in a dual-task paradigm in combination with an auditory reaction time task (RT). Performing the RT task together with the postural one was supposed to require some attentional resources that allowed estimating the attentional cost of postural control. 4 trials were performed in each condition for a total of 16 trials. Findings (1) Whereas seated non obese and obese patients exhibited similar centre of foot pressure oscillations (CoP), in the unipedal stance only obese patients strongly increased their CoP sway in comparison to controls. (2) Whatever the postural task, the additional RT task did not affect postural stability. (3) Seated, RT did not differ between the two groups. (4) RT strongly increased between the two postural conditions in the obese patients only, suggesting that body schema and the use of internal models was altered with obesity. Interpretation Obese patients needed more attentional resources to control postural stability during unipedal stance than non obese participants. This was not the case in a more simple posture such as seating. To reduce the risk of fall as indicated by the critical values of CoP displacement, obese patients must dedicate a strong large part of their attentional resources to postural control, to the detriment of non-postural events. Obese patients were not able to easily perform multitasking as healthy adults do, reflecting weakened psycho-motor abilities. PMID:21187914

  2. Kinetic instabilities in relativistic plasmas: the Harris instability revisited

    International Nuclear Information System (INIS)

    Tautz, R.C.

    2008-01-01

    Plasma instabilities that generate aperiodic fluctuations are of outstanding importance in the astrophysical context. Two prominent examples are the electromagnetic Weibel instability and the electrostatic Harris instability, which operate in initially non-magnetized and magnetized plasmas, respectively. In this talk, the original formulation of the Harris instability will be reviewed and generalizations will be presented such as the inclusion of (1) relativistic effects, (2) ion effects, and (3) mode coupling. It will be shown that, with these modifications, a powerful method has been developed for the determination of both the existence and the growth rate of low-frequency instabilities. Applications can be found in astrophysical jets, where the rest frame can be used and so no parallel motion is present. At the end of the talk, how the particle composition of gamma-ray burst jets can be predicted using the Harris technique. (author)

  3. Postural Stability of Special Warfare Combatant-Craft Crewmen With Tactical Gear.

    Science.gov (United States)

    Morgan, Paul M; Williams, Valerie J; Sell, Timothy C

    The US Naval Special Warfare's Special Warfare Combatant-Craft Crewmen (SWCC) operate on small, high-speed boats while wearing tactical gear (TG). The TG increases mission safety and success but may affect postural stability, potentially increasing risk for musculoskeletal injury. Therefore, the purpose of this study was to examine the effects of TG on postural stability during the Sensory Organization Test (SOT). Eight SWCC performed the SOT on NeuroCom's Balance Manager with TG and with no tactical gear (NTG). The status of gear was performed in randomized order. The SOT consisted of six different conditions that challenge sensory systems responsible for postural stability. Each condition was performed for three trials, resulting in a total of 18 trials. Overall performance, each individual condition, and sensory system analysis (somatosensory, visual, vestibular, preference) were scored. Data were not normally distributed therefore Wilcoxon signed-rank tests were used to compare each variable (ρ = .05). No significant differences were found between NTG and TG tests. No statistically significant differences were detected under the two TG conditions. This may be due to low statistical power, or potentially insensitivity of the assessment. Also, the amount and distribution of weight worn during the TG conditions, and the SWCC's unstable occupational platform, may have contributed to the findings. The data from this sample will be used in future research to better understand how TG affects SWCC. The data show that the addition of TG used in our study did not affect postural stability of SWCC during the SOT. Although no statistically significant differences were observed, there are clinical reasons for continued study of the effect of increased load on postural stability, using more challenging conditions, greater surface perturbations, dynamic tasks, and heavier loads. 2016.

  4. External load application in gait and posture reeducation after diffuse axonal injury of the corpus callosum. A case report

    Directory of Open Access Journals (Sweden)

    Magdalena Zawadka

    2018-06-01

    Full Text Available Traumatic brain injury caused car accidents is the one of the most common causes of diffuse axonal injury typically located at the grey-white matter junction, in the corpus callosum. A 58-year-old female patient Caucasian race was admitted to the Orthopedic and Rehabilitation Unit with head injury, broken right ulnar bone, numerous broken ribs and broken right iliac crest. Neurological examination resulted in right-sided hemiparesis. There were also coordination and balance disorders while sitting and standing. The patient was unable to walk. After physiotherapy treatment included external load application (ankle weights and rucksack with weights in gait and posture reeducation, patient has improved balance, locomotion and body posture. However, application of external loads during walk and posture reeducation needs to be further investigated with greater number of participants and control group.

  5. Strategic political postures and political market orientation

    DEFF Research Database (Denmark)

    Ormrod, Robert P.; Henneberg, Stephan C.

    2010-01-01

    by developing an integrated concept of political marketing strategy using two complementary frameworks, namely Strategic Political Postures (SPP) and Political Market Orientation (PMO). We introduce the two main concepts and derive for each of the strategic posture-specific PMO profiles as well as inter......Recently, the areas of strategic political marketing and political market orientation have been the subject of several conceptual articles which have provided the theoretical foundations for further empirical work. However, despite the close conceptual relatedness of the proposed concepts......, these have yet to be integrated to provide a more nuanced framework which both researchers and political marketing practitioners can utilise in the development of strategies and offerings with which to achieve their organizational goals. The aim of this conceptual paper is to address this deficit...

  6. Postural balance in low back pain patients

    DEFF Research Database (Denmark)

    Maribo, Thomas; Stengaard-Pedersen, Kristian; Jensen, Lone Donbæk

    2011-01-01

    Low back pain (LBP) patients have poorer postural control compared to healthy controls, and the importance of assessing and addressing balance is a matter of debate. In the clinic, balance is often tested by means of the one leg stand test (OLST) while research often employs center of pressure (Co......P) on a force platform. Portable force platforms might be of clinical relevance, but their reliability for LBP patients in a clinical setting has not been demonstrated. As LBP patients are more dependent on vision compared to healthy controls, the ratio of tests performed with eyes open and eyes closed (Romberg...... Ratio) might be of clinical interest. This study aimed to assess postural balance in LBP patients by analyzing intra-session reliability of CoP parameters on a portable force platform, the Romberg Ratio, and the OLST. Furthermore, we aimed to determine whether CoP parameters and OLST measure identical...

  7. Research of Human Postural Balance Parameters

    Directory of Open Access Journals (Sweden)

    Julius Griškevičius

    2011-02-01

    Full Text Available In present article postural balance between subjects with stroke and healthy subjects, is being investigated with eyes opened and eyes closed. In the research participated 30 healthy subjects and 15 subjects with stroke. At the same time two experimental measurements were performed – postural balance was measured using balance platform and oscillations of the centre of mass were observed using two-axial accelerometer. It was noted, that amplitudes of subjects with stroke were larger almost two times than control group’s of healthy subjects. It was find out, that ratios of pressure distribution on both left and right legs are in range from 1 to 0.9 for healthy subjects, and ratios below 0.9 are common for subjects with stroke. When subjects were standing with eyes closed, sway amplitudes were higher and the ratios of load distribution on left and right legs were lower.Article in Lithuanian

  8. Human Posture Identification Using a MIMO Array

    Directory of Open Access Journals (Sweden)

    Dai Sasakawa

    2018-03-01

    Full Text Available The elderly are constantly in danger of falling and injuring themselves without anyone realizing it. A safety-monitoring system based on microwaves can ease these concerns. The authors have proposed safety-monitoring systems that use multiple-input multiple-output (MIMO radar to localize persons by capturing their biological activities such as respiration. However, our studies to date have focused on localization, which is easier to achieve than an estimation of human postures. This paper proposes a human posture identification scheme based on height and a Doppler radar cross section (RCS as estimated by a MIMO array. This scheme allows smart home applications to dispense with contact and wearable devices. Experiments demonstrate that this method can identify the supine position (i.e., after a fall with 100% accuracy, and the average identification rate is 95.0%.

  9. Effects of posture on postoperative pulmonary function

    DEFF Research Database (Denmark)

    Nielsen, K G; Holte, Kathrine; Kehlet, H

    2003-01-01

    effect on postoperative pulmonary function in the sitting or standing position compared with the supine. Thus, avoidance of the supine position may improve postoperative pulmonary function. Three of six studies showed a positive effect on postoperative pulmonary function of the lateral side compared......BACKGROUND: Pulmonary morbidity is still a relevant complication to major surgery despite improvements in surgical technique and anaesthetic methods. Postoperative posture may be a pathogenic factor, but the effects of changes in postoperative posture on pulmonary function have not been reviewed...... with the supine. Thus, the lateral position has limited effects on pulmonary function. CONCLUSION: Changes of postoperative position from supine to sitting or standing are of major importance in the interpretation of postoperative pulmonary outcome studies and in future strategies to improve pulmonary outcome....

  10. Evaluation of body posture in nursing students.

    Science.gov (United States)

    Andrade, Marília Fernandes; Chaves, Érika de Cássia Lopes; Miguel, Michele Rita Oliveira; Simão, Talita Prado; Nogueira, Denismar Alves; Iunes, Denise Hollanda

    2017-08-28

    To investigate the body posture of nursing students before and after clinical practice. The study was developed in two stages. Initially the body posture of students of the 2nd, 4th, 6th, and 8th periods were assessed through photogrammetry. All images were analyzed in a random and masked manner with CorporisPro® 3.1.3 software. Three evaluations were performed for each angle and then the mean value was calculated. Two years later, when the 4th period students had developed their clinical internships, their body posture was again evaluated. The total sample consisted of 112 students. Comparison of their posture with the normality pattern showed that all the angles presented significant differences (pcomposta por 112 estudantes. Comparando-se os estudantes com o padrão de normalidade, todos os ângulos apresentaram diferença significativa (p< 0,00), com exceção do ângulo triângulo de Tales. Reavaliando os mesmos estudantes, houve diferença significativa nos ângulos da articulação acromioclavicular (p=0,03), da flexão de joelhos (p< 0,00) e no ângulo tibiotársico (p< 0,00). Todos os estudantes apresentaram alterações, comparadas aos valores de normalidade. Os segmentos com diferença significativa, comparando-se antes e após a prática, foram o ângulo acromioclavicular, flexo de joelho e ângulo tibiotársico, sendo os dois últimos na posição de rolamento.

  11. Human Posture Identification Using a MIMO Array

    OpenAIRE

    Dai Sasakawa; Naoki Honma; Takeshi Nakayama; Shoichi Iizuka

    2018-01-01

    The elderly are constantly in danger of falling and injuring themselves without anyone realizing it. A safety-monitoring system based on microwaves can ease these concerns. The authors have proposed safety-monitoring systems that use multiple-input multiple-output (MIMO) radar to localize persons by capturing their biological activities such as respiration. However, our studies to date have focused on localization, which is easier to achieve than an estimation of human postures. This paper pr...

  12. Locomotor circumvention strategies are altered by stroke: II. Postural Coordination.

    Science.gov (United States)

    Darekar, Anuja; Lamontagne, Anouk; Fung, Joyce

    2017-06-15

    Locomotor strategies for obstacle circumvention require appropriate postural coordination that depends on sensorimotor integration within the central nervous system. It is not known how these strategies are affected by a stroke. The objective of this study was to contrast postural coordination strategies used for obstacle circumvention between post-stroke participants (n = 12) and healthy controls (n = 12). Participants walked towards a target in a virtual environment (11 × 8 m room) with cylindrical obstacles that were stationary or approaching from head-on, or diagonally 30° left/right. Two stepping strategies for obstacle circumvention were identified: 1) side step: increase in step width by the foot ipsilateral to the side of circumvention; 2) cross step: decrease in step width by the foot contralateral to the side of circumvention. The side step strategy was favoured by post-stroke individuals in circumventing stationary and head-on approaching obstacles. In circumventing diagonally approaching obstacles, healthy controls generally veered opposite to obstacle approach (>60% trials), whereas the majority of post-stroke participants (7/12) veered to the same side of obstacle approach (V same ). Post-stroke participants who veered to the opposite side (V opp , 5/12) were more independent and faster ambulators who favoured the side step strategy in circumventing obstacles approaching from the paretic side and cross step strategy for obstacles approaching from the non-paretic side. V same participants generally favoured the side step strategy for both diagonal approaches. Segmental rotation amplitudes and latencies were largest in the V same group, and significantly greater in post-stroke participants than controls for all obstacle conditions. All participants initiated circumvention with the feet followed by the pelvis and thorax, demonstrating a caudal-rostral sequence of reorientation. Postural coordination strategies for obstacle circumvention

  13. 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.

  14. Electromyographic activity of the trunk extensor muscles: effect of varying hip position and lumbar posture during Roman chair exercise.

    Science.gov (United States)

    Mayer, John M; Verna, Joe L; Manini, Todd M; Mooney, Vert; Graves, James E

    2002-11-01

    To evaluate the effect of hip position and lumbar posture on the surface electromyographic activity of the trunk extensors during Roman chair exercise. Descriptive, repeated measures. University-based musculoskeletal research laboratory. Twelve healthy volunteers (7 men, 5 women; age range, 18-35y) without a history of low back pain were recruited from a university setting. Not applicable. Surface electromyographic activity was recorded from the lumbar extensor, gluteal, and hamstring musculature during dynamic Roman chair exercise. For each muscle group, electromyographic activity (mV/rep) was compared among exercises with internal hip rotation and external hip rotation and among exercises by using a typical lumbar posture (nonbiphasic) and a posture that accentuated lumbar lordosis (biphasic). For the lumbar extensors, electromyographic activity during exercise was 18% greater with internal hip rotation than external hip rotation (Phamstrings, there was no difference in electromyographic activity between internal and external hip rotation or between biphasic and nonbiphasic postures (P >.05). The level of recruitment of the lumbar extensors can be modified during Roman chair exercise by altering hip position and lumbar posture. Clinicians can use these data to develop progressive exercise protocols for the lumbar extensors with a variety of resistance levels without the need for complex equipment. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

  15. Impact of Computer Related Posture on the Occurrence of Musculoskeletal Discomfort among Secondary School Students in Lagos, Nigeria.

    Science.gov (United States)

    Odebiyi, D O; Olawale, O A; Adeniji, Y M

    2013-01-01

    Computers have become an essential part of life particularly in industrially advanced countries of the world. Children now have greater accessibility to computers both at school and at home. Recent studies suggest that with this increased exposure, there are associated musculoskeletal disorders (MSDs) in both school-aged children and adults. To assess the posture assumed by secondary school students during computer use and its impact on the occurrence and severity of reported musculoskeletal discomforts. Posture assumed during normal computer class, occurrence of discomforts, body parts involved and the intensity of discomforts were evaluated in 235 school aged children using Rapid Upper Limb Assessment (RULA) scale, Body Discomfort Chart (BDC) and Visual Analogue Scale (VAS) before and after normal computer class. Inferential statistics of t-test and chi-square were used to determine significance difference between variables, with level of significant set at p Computer use produced significant discomforts on the neck, shoulder and low back. There was a significant relationship between participants height and posture assumed. Two hundred and eleven (89.8%) participants reported discomforts/pain during the use of computer. Weight and height were contributory factors to the occurrence of musculoskeletal discomfort/pain (p computer use. Weight and height were implicated as factors that influenced the form of posture and the nature of the reported discomfort. Creating awareness about the knowledge of ergonomics and safety for promotion of good posture was therefore recommended.

  16. Lead effects on postural balance of children

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, A.; Shukla, R.; Bornschein, R.L.; Dietrich, K.N. (Univ. of Cincinnati, OH (USA)); Keith, R. (Univ. of Cincinnati Medical Center, OH (USA))

    1990-11-01

    The postural sway responses of 63 children with a mean age of 5.74 years were quantified with a Force Platform technique. The average maximum (max) blood lead (PbB) of these children during the first 5 years of life was 20.7 {mu}g/dL (range 9.2 to 32.5). The backward stepwise regression analysis for sway area response during the eyes-closed, no-foam test with all the covariates and confounders and the PbB parameters showed a significant relationship with peak or max PbB during the second year of life. These results are consistent with their previous study with a smaller group of children. The data have been analyzed to provide some insight into the role of various afferents for the maintenance of postural balance. The results suggests a hypothesis that if the max PbB had caused some level of impairment in the functional capacities or interconnectivity of the vestibular and/or proprioception systems at 2 years of age, then it is reasonable to assume that the redundancy in the postural afferent systems would naturally adapt to rely more on the remaining intact afferent system (in this case, vision).

  17. A postural `stressed` cerebral HMPAO case study

    Energy Technology Data Exchange (ETDEWEB)

    Williams, R.C.; Jost, G.M.; Bolitho, L.; Grantham, M. [Wangaratta District Hospital, VIC (Australia)

    1998-03-01

    Full text: This case study represents an example of the utility of postural hypoperfusion stressed HMPAO SPECT. An elderly woman of 78 with a long history of giddiness was referred to our laboratory for examination of possible cerebral ischaemia. She had recurrent dizzy episodes, sometimes posture related, over the past few years and had suffered several falls. Cerebral DSA revealed minimal disease. CT scans were reported as normal. Carotid duplex Doppler studies revealed bilateral plaque disease in the carotid bulbs extending to the origins of the ICAs which were not significant stenoses. Postural symptoms were induced by standing the patient up rapidly and HMPAO was administered at the same time. A SPECT scan of the brain was performed. Quantitative analysis showed a left to right decrease of 10.8% in the temporo-occipital area, 5.6% in the temporo-parietal area and 2.5% in the cerebellar and parietal areas. Images revealed moderately reduced tracer concentration in the left half of the cerebellum and the left occipital region extending as far forward as the temporo-parietal region A repeat HMPAO SPECT scan without stress was normal. This would appear to indicate reversible ischaemia in the left posterior region, and is consistent with the reported symptoms. This case illustrates the usefulness of HMPAO in the diagnosis of reversible cerebral ischaemia.

  18. Ice skating promotes postural control in children.

    Science.gov (United States)

    Keller, M; Röttger, K; Taube, W

    2014-12-01

    High fall rates causing injury and enormous financial costs are reported for children. However, only few studies investigated the effects of balance training in children and these studies did not find enhanced balance performance in postural (transfer) tests. Consequently, it was previously speculated that classical balance training might not be stimulating enough for children to adequately perform these exercises. Therefore, the aim of this study is to evaluate the influence of ice skating as an alternative form of balance training. Volunteers of an intervention (n = 17; INT: 13.1 ± 0.4 years) and a control group (n = 13; CON: 13.2 ± 0.3 years) were tested before and after training in static and dynamic postural transfer tests. INT participated in eight sessions of ice skating during education lessons, whereas CON participated in normal physical education. Enhanced balance performance was observed in INT but not in CON when tested on an unstable free-swinging platform (P skating in children. More importantly, participating children improved static and dynamic balance control in postural tasks that were not part of the training. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. A postural 'stressed' cerebral HMPAO case study

    International Nuclear Information System (INIS)

    Williams, R.C.; Jost, G.M.; Bolitho, L.; Grantham, M.

    1998-01-01

    Full text: This case study represents an example of the utility of postural hypoperfusion stressed HMPAO SPECT. An elderly woman of 78 with a long history of giddiness was referred to our laboratory for examination of possible cerebral ischaemia. She had recurrent dizzy episodes, sometimes posture related, over the past few years and had suffered several falls. Cerebral DSA revealed minimal disease. CT scans were reported as normal. Carotid duplex Doppler studies revealed bilateral plaque disease in the carotid bulbs extending to the origins of the ICAs which were not significant stenoses. Postural symptoms were induced by standing the patient up rapidly and HMPAO was administered at the same time. A SPECT scan of the brain was performed. Quantitative analysis showed a left to right decrease of 10.8% in the temporo-occipital area, 5.6% in the temporo-parietal area and 2.5% in the cerebellar and parietal areas. Images revealed moderately reduced tracer concentration in the left half of the cerebellum and the left occipital region extending as far forward as the temporo-parietal region A repeat HMPAO SPECT scan without stress was normal. This would appear to indicate reversible ischaemia in the left posterior region, and is consistent with the reported symptoms. This case illustrates the usefulness of HMPAO in the diagnosis of reversible cerebral ischaemia

  20. A research on the postural stability of a person wearing the lower limb exoskeletal robot by the HAT model.

    Science.gov (United States)

    Chang, Minsu; Kim, Yeongmin; Lee, Yoseph; Jeon, Doyoung

    2017-07-01

    This paper proposes a method of detecting the postural stability of a person wearing the lower limb exoskeletal robot with the HAT(Head-Arm-Trunk) model. Previous studies have shown that the human posture is stable when the CoM(Center of Mass) of the human body is placed on the BoS(Base of Support). In the case of the lower limb exoskeletal robot, the motion data, which are used for the CoM estimation, are acquired by sensors in the robot. The upper body, however, does not have sensors in each segment so that it may cause the error of the CoM estimation. In this paper, the HAT(Head-Arm-Trunk) model which combines head, arms, and torso into a single segment is considered because the motion of head and arms are unknown due to the lack of sensors. To verify the feasibility of HAT model, the reflecting markers are attached to each segment of the whole human body and the exact motion data are acquired by the VICON to compare the COM of the full body model and HAT model. The difference between the CoM with full body and that with HAT model is within 20mm for the various motions of head and arms. Based on the HAT model, the XCoM(Extrapolated Center of Mass) which includes the velocity of the CoM is used for prediction of the postural stability. The experiment of making unstable posture shows that the XCoM of the whole body based on the HAT model is feasible to detect the instance of postural instability earlier than the CoM by 20-250 msec. This result may be used for the lower limb exoskeletal robot to prepare for any action to prevent the falling down.

  1. Instabilities in the aether

    International Nuclear Information System (INIS)

    Carroll, Sean M.; Dulaney, Timothy R.; Gresham, Moira I.; Tam, Heywood

    2009-01-01

    We investigate the stability of theories in which Lorentz invariance is spontaneously broken by fixed-norm vector 'aether' fields. Models with generic kinetic terms are plagued either by ghosts or by tachyons, and are therefore physically unacceptable. There are precisely three kinetic terms that are not manifestly unstable: a sigma model (∂ μ A ν ) 2 , the Maxwell Lagrangian F μν F μν , and a scalar Lagrangian (∂ μ A μ ) 2 . The timelike sigma-model case is well defined and stable when the vector norm is fixed by a constraint; however, when it is determined by minimizing a potential there is necessarily a tachyonic ghost, and therefore an instability. In the Maxwell and scalar cases, the Hamiltonian is unbounded below, but at the level of perturbation theory there are fewer degrees of freedom and the models are stable. However, in these two theories there are obstacles to smooth evolution for certain choices of initial data.

  2. Posterolateral elbow joint instability

    DEFF Research Database (Denmark)

    Olsen, Bo Sanderhoff; Søjbjerg, Jens Ole; Nielsen, K K

    1998-01-01

    Thirty-five osteoligamentous elbows were included in a study on the kinematics of posterolateral elbow joint instability during the pivot shift test (PST) before and after separate ligament cuttings in the lateral collateral ligament complex (LCLC). Division of the annular ligament or the lateral...... ulnar collateral ligament caused no laxity during the PST. Division of the lateral collateral ligament caused maximal laxity of 4 degrees and 23 degrees during forced PST in valgus and external rotation (supination), respectively. Cutting of the LCLC at the ulnar or the humeral insertion was necessary...... for any PST stressed elbow joint laxity to occur. Total division of the LCLC induced a maximal laxity of 7.9 degrees and 37 degrees during forced PST in valgus and external rotation (supination), respectively. This study suggests the lateral collateral ligament to be the primary soft tissue constraint...

  3. Instabilities in electromagnetic quasilevitation.

    Science.gov (United States)

    Spragg, Kirk; Letout, Sebastien; Ernst, R; Sneyd, Alfred; Fautrelle, Yves

    2014-05-01

    We investigate free-surface instabilities occurring in various industrial processes involving liquid metal. Of particular interest is the behavior of the free surface of a pool of liquid metal when it is submitted to an alternating magnetic field. Experimentally, we study the effect of a vertical alternating medium-frequency magnetic field on an initially circular pool. We observe various types of behavior according to magnetic field amplitude, e.g., axisymmetric deformations, azimuthal mode structures, slow radial oscillation of the pool perimeter, and random rotation of the pool around its center. Drop rotation could be attributed to nonsymmetric shape deformations. The effect of oxidation leads to drastic changes in pool behavior. The experimental results are then compared to a linear stability analysis of the free surface of a circular liquid drop.

  4. From instabilities to multifragmentation

    International Nuclear Information System (INIS)

    Chomaz, P.; Jacquot, B.; Colonna, M.; Guarnera, A.

    1994-01-01

    The main purpose of this article is to show that, in many physical situations, the spinodal decomposition of unstable systems can be correctly described by stochastic mean-field approaches. Such theories predict that the occurrence of spinodal instability leading the multifragmentation of an expended nuclear system, can be signed through the observation of time scales for the fragment formation of the order of 100 fm/c and of typical fragment size around A=20. We will finally discuss the fact that these fragments are formed at finite temperature and so can subsequently decay in flight. Finally, we will give some hints about possible experimental signals of such first order phase transitions. (authors). 12 refs., 5 figs

  5. From instabilities to multifragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, P.; Jacquot, B. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Colonna, M.; Guarnera, A. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)]|[Istituto Nazionale di Fisica Nucleare, Bologna (Italy)

    1994-12-31

    The main purpose of this article is to show that, in many physical situations, the spinodal decomposition of unstable systems can be correctly described by stochastic mean-field approaches. Such theories predict that the occurrence of spinodal instability leading the multifragmentation of an expended nuclear system, can be signed through the observation of time scales for the fragment formation of the order of 100 fm/c and of typical fragment size around A=20. We will finally discuss the fact that these fragments are formed at finite temperature and so can subsequently decay in flight. Finally, we will give some hints about possible experimental signals of such first order phase transitions. (authors). 12 refs., 5 figs.

  6. Saturation of equatorial inertial instability

    NARCIS (Netherlands)

    Kloosterziel, R.C.; Orlandi, P.; Carnevale, G.F.

    2015-01-01

    Inertial instability in parallel shear flows and circular vortices in a uniformly rotating system ( $f$f-plane) redistributes absolute linear momentum or absolute angular momentum in such a way as to neutralize the instability. In previous studies we showed that, in the absence of other

  7. Internal rotor friction instability

    Science.gov (United States)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1990-01-01

    The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations.

  8. Effect of Time after Anterior Cruciate Ligament Tears on Proprioception and Postural Stability.

    Directory of Open Access Journals (Sweden)

    Dae-Hee Lee

    Full Text Available This study was designed to compare proprioception and postural stability in patients with acute (time from injury ≤ 3 months and chronic (time from injury > 3 months ACL tears, and to evaluate the correlation between time interval after ACL injury and proprioception. Thigh muscle strength, postural stability, and joint position sense were compared in 48 patients with acute ACL tears and in 28 with chronic ACL tears. Maximal torque (60°/sec of the quadriceps and hamstring was evaluated using an isokinetic testing device. Postural stability was determined from the anterior-posterior (APSI, medial-lateral (MLSI, and overall (OSI stability indices using stabilometry. Joint position sense was also tested by reproduction of passive positioning (RPP. Muscle strengths and stability indices on both the involved and uninvolved sides were similar in the acute and chronic ACL tear groups. RPP on the involved side was significantly greater in the chronic than in the acute ACL tear group (7.8° vs. 5.6°, P = 0.041. Two of three stability indices (APSI, OSI and RPP were significantly greater on the involved than the uninvolved side in the chronic ACL tear group.

  9. Effectiveness of neuromuscular taping on pronated foot posture and walking plantar pressures in amateur runners.

    Science.gov (United States)

    Aguilar, María Bravo; Abián-Vicén, Javier; Halstead, Jill; Gijon-Nogueron, Gabriel

    2016-04-01

    To determine the effect kinesiotaping (KT) versus sham kinesiotaping (sham KT) in the repositioning of pronated feet after a short running. Prospective, randomised, double-blinded, using a repeated-measures design with no cross-over. 116 amateur runners were screened by assessing the post-run (45min duration) foot posture to identify pronated foot types (defined by Foot Posture Index [FPI] score of ≥6). Seventy-three runners met the inclusion criteria and were allocated into two treatment groups, KT (n=49) and sham KT (n=24). After applying either the KT or sham KT and completing 45min of running (mean speed of 12km/h), outcome measures were collected (FPI and walking Pedobarography). FPI was reduced in both groups, more so in the KT group (mean FPI between group difference=0.9, CI 0.1-1.9), with a score closer to neutral. There were statistically significant differences between KT and sham KT (p<.05 and p<.01) in pressure time integral, suggesting that sham KT had a greater effect. KT may be of some assistant to clinicians in correction of pronated foot posture in a short-term. There was no effect of KT, however on pressure variables at heel strike or toe-off following a short duration of running, the sham KT technique had a greater effect. Therapy, level 1b. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. Dynamical Instability and Soliton Concept

    International Nuclear Information System (INIS)

    Kartavenko, V.G.

    1994-01-01

    The problem of dynamical instability and clustering (stable fragments formation) in a breakup of excited nuclear systems are considered from the points of view of the soliton concept. It is noted that the volume (spinodal) instability can be associated with nonlinear terms, and the surface (Rayleigh-Taylor type) instability, with the dispersion terms in the evolution equations. The spinodal instability and the Rayleigh-Taylor instability may compensate each other and lead to stable quasi-soliton type objects. The simple analytical model is presented to illustrate this physical picture. The time evolution of an initially compressed cold nuclear system is analysed in the framework of the inverse mean-field method. It is demonstrated that the nonlinearity and dispersion terms of the evolution equations can lead to clusterization in the final channel. 8 p

  11. Beam instability Workshop - plenary sessions

    International Nuclear Information System (INIS)

    2001-01-01

    The purpose of this workshop was to provide a review of the mechanisms of limiting beam instabilities, their cures, including feedback, and beam measurement for synchrotron radiation light sources. 12 plenary sessions took place whose titles are: 1) challenging brilliance and lifetime issues with increasing currents; 2) limiting instabilities in multibunch; 3) experience from high currents in B factories; 4) longitudinal dynamics in high intensity/bunch; 5) Transverse instabilities for high intensity/bunch; 6) working group introduction from ESRF experience; 7) impedance modelling: simulations, minimization; 8) report on the broadband impedance measurements and modelling workshop; 9) feedback systems for synchrotron light sources; 10) beam instabilities diagnostics; 11) harmonic cavities: the pros and cons; and 12) experimental study of fast beam-ion instabilities at PLS. This document gathers the 12 articles that were presented during these sessions

  12. Beam instability Workshop - plenary sessions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The purpose of this workshop was to provide a review of the mechanisms of limiting beam instabilities, their cures, including feedback, and beam measurement for synchrotron radiation light sources. 12 plenary sessions took place whose titles are: 1) challenging brilliance and lifetime issues with increasing currents; 2) limiting instabilities in multibunch; 3) experience from high currents in B factories; 4) longitudinal dynamics in high intensity/bunch; 5) Transverse instabilities for high intensity/bunch; 6) working group introduction from ESRF experience; 7) impedance modelling: simulations, minimization; 8) report on the broadband impedance measurements and modelling workshop; 9) feedback systems for synchrotron light sources; 10) beam instabilities diagnostics; 11) harmonic cavities: the pros and cons; and 12) experimental study of fast beam-ion instabilities at PLS. This document gathers the 12 articles that were presented during these sessions.

  13. Electron/electron acoustic instability

    International Nuclear Information System (INIS)

    Gary, S.P.

    1987-01-01

    The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma

  14. Waste management in Greater Vancouver

    Energy Technology Data Exchange (ETDEWEB)

    Carrusca, K. [Greater Vancouver Regional District, Burnaby, BC (Canada); Richter, R. [Montenay Inc., Vancouver, BC (Canada)]|[Veolia Environmental Services, Vancouver, BC (Canada)

    2006-07-01

    An outline of the Greater Vancouver Regional District (GVRD) waste-to-energy program was presented. The GVRD has an annual budget for solid waste management of $90 million. Energy recovery revenues from solid waste currently exceed $10 million. Over 1,660,00 tonnes of GVRD waste is recycled, and another 280,000 tonnes is converted from waste to energy. The GVRD waste-to-energy facility combines state-of-the-art combustion and air pollution control, and has processed over 5 million tonnes of municipal solid waste since it opened in 1988. Its central location minimizes haul distance, and it was originally sited to utilize steam through sales to a recycle paper mill. The facility has won several awards, including the Solid Waste Association of North America award for best facility in 1990. The facility focuses on continual improvement, and has installed a carbon injection system; an ammonia injection system; a flyash stabilization system; and heat capacity upgrades in addition to conducting continuous waste composition studies. Continuous air emissions monitoring is also conducted at the plant, which produces a very small percentage of the total air emissions in metropolitan Vancouver. The GVRD is now seeking options for the management of a further 500,000 tonnes per year of solid waste, and has received 23 submissions from a range of waste energy technologies which are now being evaluated. It was concluded that waste-to-energy plants can be located in densely populated metropolitan areas and provide a local disposal solution as well as a source of renewable energy. Other GVRD waste reduction policies were also reviewed. refs., tabs., figs.

  15. 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.

  16. Parametric decay instabilities in ECR heated plasmas

    International Nuclear Information System (INIS)

    Porkolab, M.

    1982-01-01

    The possibility of parametric excitation of electron Bernstein waves and low frequency ion oscillations during ECR heating at omega/sub o/ approx. = l omega/sub ce/, l = 1,2 is examined. In particular, the thresholds for such instabilities are calculated. It is found that Bernstein waves and lower hybrid quasi-modes have relatively low homogeneous where T/sub e/ approx. = T/sub i/. Thus, these processes may lead to nonlinear absorption and/or scattering of the incident pump wave. The resulting Bernstein waves may lead to either more effective heating (especially during the start-up phase) or to loss of microwave energy if the decay waves propagate out of the system before their energy is absorbed by particles. While at omega/sub o/ = omega/sub UH/ the threshold is reduced due to the WKB enhancement of the pump wave, (and this instability may be important in tokamaks) in EBT's and tandem mirrors the instability at omega /sub o/ greater than or equal to 2 omega/sub ce/ may be important. The instability may persist even if omega > 2 omega/sub ce/ and this may be the case during finite beta depression of the magnetic field in which case the decay waves may be trapped in the local magnetic well so that convective losses are minimized. The excited fluctuations may lead to additional scattering of the ring electrons and the incident microwave fields. Application of these calculations to ECR heating of tokamaks, tandem mirrors, and EBT's will be examined

  17. Gravitational Instabilities in Circumstellar Disks

    Science.gov (United States)

    Kratter, Kaitlin; Lodato, Giuseppe

    2016-09-01

    Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review, we focus on the role of gravitational instability in this process. We begin with a brief overview of the observational evidence for massive disks that might be subject to gravitational instability and then highlight the diverse ways in which the instability manifests itself in protostellar and protoplanetary disks: the generation of spiral arms, small-scale turbulence-like density fluctuations, and fragmentation of the disk itself. We present the analytic theory that describes the linear growth phase of the instability supplemented with a survey of numerical simulations that aim to capture the nonlinear evolution. We emphasize the role of thermodynamics and large-scale infall in controlling the outcome of the instability. Despite apparent controversies in the literature, we show a remarkable level of agreement between analytic predictions and numerical results. In the next part of our review, we focus on the astrophysical consequences of the instability. We show that the disks most likely to be gravitationally unstable are young and relatively massive compared with their host star, Md/M*≥0.1. They will develop quasi-stable spiral arms that process infall from the background cloud. Although instability is less likely at later times, once infall becomes less important, the manifestations of the instability are more varied. In this regime, the disk thermodynamics, often regulated by stellar irradiation, dictates the development and evolution of the instability. In some cases the instability may lead to fragmentation into bound companions. These companions are more likely to be brown dwarfs or stars than planetary mass objects. Finally, we highlight open questions related to the development of a turbulent cascade in thin disks and the role of mode-mode coupling in setting the maximum angular

  18. Thermal shrinkage for shoulder instability.

    Science.gov (United States)

    Toth, Alison P; Warren, Russell F; Petrigliano, Frank A; Doward, David A; Cordasco, Frank A; Altchek, David W; O'Brien, Stephen J

    2011-07-01

    Thermal capsular shrinkage was popular for the treatment of shoulder instability, despite a paucity of outcomes data in the literature defining the indications for this procedure or supporting its long-term efficacy. The purpose of this study was to perform a clinical evaluation of radiofrequency thermal capsular shrinkage for the treatment of shoulder instability, with a minimum 2-year follow-up. From 1999 to 2001, 101 consecutive patients with mild to moderate shoulder instability underwent shoulder stabilization surgery with thermal capsular shrinkage using a monopolar radiofrequency device. Follow-up included a subjective outcome questionnaire, discussion of pain, instability, and activity level. Mean follow-up was 3.3 years (range 2.0-4.7 years). The thermal capsular shrinkage procedure failed due to instability and/or pain in 31% of shoulders at a mean time of 39 months. In patients with unidirectional anterior instability and those with concomitant labral repair, the procedure proved effective. Patients with multidirectional instability had moderate success. In contrast, four of five patients with isolated posterior instability failed. Thermal capsular shrinkage has been advocated for the treatment of shoulder instability, particularly mild to moderate capsular laxity. The ease of the procedure makes it attractive. However, our retrospective review revealed an overall failure rate of 31% in 80 patients with 2-year minimum follow-up. This mid- to long-term cohort study adds to the literature lacking support for thermal capsulorrhaphy in general, particularly posterior instability. The online version of this article (doi:10.1007/s11420-010-9187-7) contains supplementary material, which is available to authorized users.

  19. Inactivity periods and postural change speed can explain atypical postural change patterns of Caenorhabditis elegans mutants.

    Science.gov (United States)

    Fukunaga, Tsukasa; Iwasaki, Wataru

    2017-01-19

    With rapid advances in genome sequencing and editing technologies, systematic and quantitative analysis of animal behavior is expected to be another key to facilitating data-driven behavioral genetics. The nematode Caenorhabditis elegans is a model organism in this field. Several video-tracking systems are available for automatically recording behavioral data for the nematode, but computational methods for analyzing these data are still under development. In this study, we applied the Gaussian mixture model-based binning method to time-series postural data for 322 C. elegans strains. We revealed that the occurrence patterns of the postural states and the transition patterns among these states have a relationship as expected, and such a relationship must be taken into account to identify strains with atypical behaviors that are different from those of wild type. Based on this observation, we identified several strains that exhibit atypical transition patterns that cannot be fully explained by their occurrence patterns of postural states. Surprisingly, we found that two simple factors-overall acceleration of postural movement and elimination of inactivity periods-explained the behavioral characteristics of strains with very atypical transition patterns; therefore, computational analysis of animal behavior must be accompanied by evaluation of the effects of these simple factors. Finally, we found that the npr-1 and npr-3 mutants have similar behavioral patterns that were not predictable by sequence homology, proving that our data-driven approach can reveal the functions of genes that have not yet been characterized. We propose that elimination of inactivity periods and overall acceleration of postural change speed can explain behavioral phenotypes of strains with very atypical postural transition patterns. Our methods and results constitute guidelines for effectively finding strains that show "truly" interesting behaviors and systematically uncovering novel gene

  20. A flexed posture in elderly patients is associated with impairments in postural control during walking.

    Science.gov (United States)

    de Groot, Maartje H; van der Jagt-Willems, Hanna C; van Campen, Jos P C M; Lems, Willem F; Beijnen, Jos H; Lamoth, Claudine J C

    2014-02-01

    A flexed posture (FP) is characterized by protrusion of the head and an increased thoracic kyphosis (TK), which may be caused by osteoporotic vertebral fractures (VFs). These impairments may affect motor function, and consequently increase the risk of falling and fractures. The aim of the current study was therefore to examine postural control during walking in elderly patients with FP, and to investigate the relationship with geriatric phenomena that may cause FP, such as increased TK, VFs, frailty, polypharmacy and cognitive impairments. Fifty-six elderly patients (aged 80 ± 5.2 years; 70% female) walked 160 m at self-selected speed while trunk accelerations were recorded. Walking speed, mean stride time and coefficient of variation (CV) of stride time were recorded. In addition, postural control during walking was quantified by time-dependent variability measures derived from the theory of stochastic dynamics, indicating smoothness, degree of predictability, and local stability of trunk acceleration patterns. Twenty-five patients (45%) had FP and demonstrated a more variable and less structured gait pattern, and a more irregular trunk acceleration pattern than patients with normal posture. FP was significantly associated with an increased TK, but not with other geriatric phenomena. An increased TK may bring the body's centre of mass forward, which requires correcting responses, and reduces the ability to respond on perturbation, which was reflected by higher variation in the gait pattern in FP-patients. Impairments in postural control during walking are a major risk factor for falling: the results indicate that patients with FP have impaired postural control during walking and might therefore be at increased risk of falling. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Instability timescale for the inclination instability in the solar system

    Science.gov (United States)

    Zderic, Alexander; Madigan, Ann-Marie; Fleisig, Jacob

    2018-04-01

    The gravitational influence of small bodies is often neglected in the study of solar system dynamics. However, this is not always an appropriate assumption. For example, mutual secular torques between low mass particles on eccentric orbits can result in a self-gravity instability (`inclination instability'; Madigan & McCourt 2016). During the instability, inclinations increase exponentially, eccentricities decrease (detachment), and orbits cluster in argument of perihelion. In the solar system, the orbits of the most distant objects show all three of these characteristics (high inclination: Volk & Malhotra (2017), detachment: Delsanti & Jewitt (2006), and argument of perihelion clustering: Trujillo & Sheppard (2014)). The inclination instability is a natural explanation for these phenomena.Unfortunately, full N-body simulations of the solar system are unfeasible (N ≈ O(1012)), and the behavior of the instability depends on N, prohibiting the direct application of lower N simulations. Here we present the instability timescale's functional dependence on N, allowing us to extrapolate our simulation results to that appropriate for the solar system. We show that ~5 MEarth of small icy bodies in the Sedna region is sufficient for the inclination instability to occur in the outer solar system.

  2. Effect of fibular repositioning taping in adult basketball players with chronic ankle instability: a randomized, placebo-controlled, crossover trial.

    Science.gov (United States)

    Alves, Yanina; Ribeiro, Fernando; Silva, Anabela G

    2017-07-05

    Chronic ankle instability presents a high incidence and prevalence in basketbal players. It's important to develop strategies to reduce the functional and mechanical limitations resulting from this condition. To compare the effect of Mulligan ́s fibular repositioning taping with a placebo taping immediatly after application and after a running test (Yo-Yo IRT). 16 adult basketball players (10 male, 6 female) with chronic ankle instability and mean age 21.50 ± 2.76 years old. Assessment of static postural control (15 seconds of unipedal stance test with eyes closed in a force platform), functional performance (figure 8 hop test and lateral hop test) and neuromuscular control (peroneus longus latency time in sudden inversion) in two conditions: Mulligan and Placebo. No significant effect was found for the intervantion factor in both hop tests (p>0.170), but there was a significant effect for the time factor (p<0.03). For the peroneus longus latency time, there was a significant interaction between factors (p=0.028) and also for time (p=0.042). No significant effect was found for any of the static postural control variables (area, speed and total displacement) (p≥0.10). There was no differences between Mulligan's fibular repositioning taping and Placebo taping in postural control and functional performance in basketball players with chronic ankle instability. However, Mulligan's taping appears to reduce peroneus longus latency time after a running when compared with a placebo taping.

  3. Time-of-day influences postural balance in older adults

    DEFF Research Database (Denmark)

    Jorgensen, M G; Rathleff, Michael Skovdal; Laessoe, U

    2012-01-01

    Postural balance assessments are performed in both clinical and basic research settings on a daily basis. During a 24-h time span our physiology and physical performance undergo radical changes as we are influenced by the circadian rhythm. The time-of-day interaction on postural balance is unknow...... in older adults. The aim of this study was to investigate the time-of-day effect on postural balance in older adults....

  4. The study of postural workload in assembly of furniture upholstery

    OpenAIRE

    Marek Lasota Andrzej; Hankiewicz Krzysztof

    2017-01-01

    The productivity of the workers is affected by the Work-related Musculoskeletal Disorders (WRMSDs) which common cause of health problems, sick leave and it can result in decreased quality of work and increased absenteeism. The objective of this study is to evaluate and investigate the postural workload of sewing machine operators in the assembly of upholstery in furniture factory by using the Ovako Working Posture Analysing System (OWAS) with sampling. The results indicated that posture code ...

  5. Nonplantigrade Foot Posture: A Constraint on Dinosaur Body Size

    OpenAIRE

    Kubo, Tai; Kubo, Mugino O.

    2016-01-01

    Dinosaurs had functionally digitigrade or sub-unguligrade foot postures. With their immediate ancestors, dinosaurs were the only terrestrial nonplantigrades during the Mesozoic. Extant terrestrial mammals have different optimal body sizes according to their foot posture (plantigrade, digitigrade, and unguligrade), yet the relationship of nonplantigrade foot posture with dinosaur body size has never been investigated, even though the body size of dinosaurs has been studied intensively. Accordi...

  6. Change of Safe Needling Depth at Acupoint GB21 according to Posture and Breathing

    Directory of Open Access Journals (Sweden)

    Hongmin Chu

    2018-01-01

    Full Text Available Acupoint GB21 (Jianjing is used for treating back and shoulder pain but is associated with a risk of pneumothorax. We aimed to determine the SND (safe needling depth at GB21 according to posture and breathing in real time. Ultrasonographic images of GB21 during normal breathing, inspiration, and expiration in a SP (sitting position were acquired for 52 healthy volunteers. Images were also acquired during normal respiration in the PP (prone position with arms raised and lowered. The average SND was greater for men than for women (p<0.05. Analysis of variance revealed that the SND was greater for the PP than for the SP (p=0.01 and p<0.05, resp.. Although the SND tended to change according to posture, the average depth tended to deviate widely in some subjects. During breathing, the differences between inspiration and expiration were less than 1 mm in most subjects, but some showed differences more than 4.5 mm. The SND at GB21 was greater in overweight subjects and significantly greater in the PP and during maximal expiration. However, intragroup differences were greater than the intergroup differences. Therefore, it is dangerous to simply apply needling depth on a gender or BMI basis. The practitioner would adjust the SND by examining the individual anatomical structures.

  7. Review on two-phase flow instabilities in narrow spaces

    International Nuclear Information System (INIS)

    Tadrist, L.

    2007-01-01

    Instabilities in two-phase flow have been studied since the 1950s. These phenomena may appear in power generation and heat transfer systems where two-phase flow is involved. Because of thermal management in small size systems, micro-fluidics plays an important role. Typical processes must be considered when the channel hydraulic diameter becomes very small. In this paper, a brief review of two-phase flow instabilities encountered in channels having hydraulic diameters greater than 10 mm are presented. The main instability types are discussed according to the existing experimental results and models. The second part of the paper examines two-phase flow instabilities in narrow spaces. Pool and flow boiling cases are considered. Experiments as well as theoretical models existing in the literature are examined. It was found that several experimental works evidenced these instabilities meanwhile only limited theoretical developments exist in the literature. In the last part of the paper an interpretation of the two-phase flow instabilities linked to narrow spaces are presented. This approach is based on characteristic time scales of the two-phase flow and bubble growth in the capillaries

  8. Functional Instability of the Ankle Joint: Etiopathogenesis

    Directory of Open Access Journals (Sweden)

    Aydan ÖRSÇELİK

    2016-09-01

    Full Text Available Ankle sprain is one of the most common sports injuries. Chronic ankle instability is a common complication of ankle sprains. Two causes of chronic ankle instability are mechanical instability and functional instability. It is important to understand functional instability etiopathogenesis of the ankle joint in order to guide diagnosis and treatment. This article aims to understand the etiopathogenesis of functional ankle instability.

  9. Postural adjustments are modulated by manual task complexity

    Directory of Open Access Journals (Sweden)

    Luis Augusto Teixeira

    2009-09-01

    Full Text Available Daily life activities of humans are characterized by dual tasks, in which a manual task is performed concomitantly with a postural task. Based on the assumption that both manual and postural tasks require attentional resources, no consensus exists as to how the central nervous system modulates postural adjustments in dual tasks. The aim of the present study was to analyze the effect of a manual task requiring attentional resources on shoulder and ankle adjustments as a function of the direction and predictability of postural perturbation. The participants (n=6 were evaluated during the performance of a simple and a complex manual task, while the base of support was moved backward or forward. Latency of activation of the tibialis anterior and gastroc-nemius muscles and angular acceleration of the shoulder were analyzed. The results showed that execution of the complex manual task delayed postural adjustment. Moreover, this delay occurred differently depending on the direction of postural perturbation. The delay in postural adjustment occurred proximally in the case of anterior displacement of the platform, and distally in the case of posterior displacement. Postural adjustments were more affected by the attentional task than by the predictability of platform displacement. These results are consistent with the concept of an integrated control between manual actions and the maintenance of static posture.

  10. Eye Movements Affect Postural Control in Young and Older Females.

    Science.gov (United States)

    Thomas, Neil M; Bampouras, Theodoros M; Donovan, Tim; Dewhurst, Susan

    2016-01-01

    Visual information is used for postural stabilization in humans. However, little is known about how eye movements prevalent in everyday life interact with the postural control system in older individuals. Therefore, the present study assessed the effects of stationary gaze fixations, smooth pursuits, and saccadic eye movements, with combinations of absent, fixed and oscillating large-field visual backgrounds to generate different forms of retinal flow, on postural control in healthy young and older females. Participants were presented with computer generated visual stimuli, whilst postural sway and gaze fixations were simultaneously assessed with a force platform and eye tracking equipment, respectively. The results showed that fixed backgrounds and stationary gaze fixations attenuated postural sway. In contrast, oscillating backgrounds and smooth pursuits increased postural sway. There were no differences regarding saccades. There were also no differences in postural sway or gaze errors between age groups in any visual condition. The stabilizing effect of the fixed visual stimuli show how retinal flow and extraocular factors guide postural adjustments. The destabilizing effect of oscillating visual backgrounds and smooth pursuits may be related to more challenging conditions for determining body shifts from retinal flow, and more complex extraocular signals, respectively. Because the older participants matched the young group's performance in all conditions, decreases of posture and gaze control during stance may not be a direct consequence of healthy aging. Further research examining extraocular and retinal mechanisms of balance control and the effects of eye movements, during locomotion, is needed to better inform fall prevention interventions.

  11. The dentist’s operating posture – ergonomic aspects

    Science.gov (United States)

    Pîrvu, C; Pătraşcu, I; Pîrvu, D; Ionescu, C

    2014-01-01

    Abstract The practice of dentistry involves laborious high finesse dental preparations, precision and control in executions that require a particular attention, concentration and patience of the dentist and finally the dentist’s physical and mental resistance. The optimal therapeutic approach and the success of practice involve special working conditions for the dentist and his team in an ergonomic environment. The meaning of the posture in ergonomics is the manner in which different parts of the body are located and thus the reports are established between them in order to allow a special task execution. This article discusses the posture adopted by dentists when they work, beginning with the balanced posture and going to different variants of posture. The ideal posture of a dentist gives him, on the one hand the optimal working conditions (access, visibility and control in the mouth) and on the other hand, physical and psychological comfort throughout the execution of the clinical acts. Although the theme of dentist posture is treated with great care and often presented in the undergraduate courses and the continuing education courses on ergonomics in dentistry, many dentists do not know the subject well enough nor the theoretical issues and therefore nor the practical applicability. The risk and perspective of the musculoskeletal disorders related to unbalanced postures should determine the dentists take postural corrective actions and compensation measures in order to limit the negative effects of working in a bad posture. PMID:25184007

  12. Multisensory training for postural sway control in non-injured elderly ...

    African Journals Online (AJOL)

    Multisensory training for postural sway control in non-injured elderly females. ... Elderly adults demonstrate increased postural sway, which may ultimately lead to falls. ... Keywords: multisensory training, postural sway control, balance ability, ...

  13. Size effects on cavitation instabilities

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2006-01-01

    growth is here analyzed for such cases. A finite strain generalization of a higher order strain gradient plasticity theory is applied for a power-law hardening material, and the numerical analyses are carried out for an axisymmetric unit cell containing a spherical void. In the range of high stress...... triaxiality, where cavitation instabilities are predicted by conventional plasticity theory, such instabilities are also found for the nonlocal theory, but the effects of gradient hardening delay the onset of the instability. Furthermore, in some cases the cavitation stress reaches a maximum and then decays...... as the void grows to a size well above the characteristic material length....

  14. On the functional integration between postural and supra-postural tasks on the basis of contextual cues and task constraint.

    Science.gov (United States)

    de Lima, Andrea Cristina; de Azevedo Neto, Raymundo Machado; Teixeira, Luis Augusto

    2010-10-01

    In order to evaluate the effects of uncertainty about direction of mechanical perturbation and supra-postural task constraint on postural control, young adults had their upright stance perturbed while holding a tray in a horizontal position. Stance was perturbed by moving forward or backward a supporting platform, contrasting situations of certainty versus uncertainty of direction of displacement. Increased constraint on postural stability was imposed by a supra-postural task of equilibrating a cylinder on the tray. Performance was assessed through EMG of anterior leg muscles, angular displacement of the main joints involved in the postural reactions and displacement of the tray. Results showed that both certainty on the direction of perturbation and increased supra-postural task constraint led to decreased angular displacement of the knee and the hip. Furthermore, combination of certainty and high supra-postural task constraint produced shorter latency of muscular activation. Such postural responses were paralleled by decreased displacement of the tray. These results suggest a functional integration between the tasks, with central set priming reactive postural responses from contextual cues and increased stability demand. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Sheared Electroconvective Instability

    Science.gov (United States)

    Kwak, Rhokyun; Pham, Van Sang; Lim, Kiang Meng; Han, Jongyoon

    2012-11-01

    Recently, ion concentration polarization (ICP) and related phenomena draw attention from physicists, due to its importance in understanding electrochemical systems. Researchers have been actively studying, but the complexity of this multiscale, multiphysics phenomenon has been limitation for gaining a detailed picture. Here, we consider electroconvective(EC) instability initiated by ICP under pressure-driven flow, a scenario often found in electrochemical desalinations. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of sheared EC: unidirectional vortex structures, its size selection and vortex propagation. Selected by balancing the external pressure gradient and the electric body force, which generates Hagen-Poiseuille(HP) flow and vortical EC, the dimensionless EC thickness scales as (φ2 /UHP)1/3. The pressure-driven flow(or shear) suppresses unfavorably-directed vortices, and simultaneously pushes favorably-directed vortices with constant speed, which is linearly proportional to the total shear of HP flow. This is the first systematic characterization of sheared EC, which has significant implications on the optimization of electrodialysis and other electrochemical systems.

  16. Postural threat differentially affects the feedforward and feedback components of the vestibular-evoked balance response.

    Science.gov (United States)

    Osler, Callum J; Tersteeg, M C A; Reynolds, Raymond F; Loram, Ian D

    2013-10-01

    Circumstances may render the consequence of falling quite severe, thus maximising the motivation to control postural sway. This commonly occurs when exposed to height and may result from the interaction of many factors, including fear, arousal, sensory information and perception. Here, we examined human vestibular-evoked balance responses during exposure to a highly threatening postural context. Nine subjects stood with eyes closed on a narrow walkway elevated 3.85 m above ground level. This evoked an altered psycho-physiological state, demonstrated by a twofold increase in skin conductance. Balance responses were then evoked by galvanic vestibular stimulation. The sway response, which comprised a whole-body lean in the direction of the edge of the walkway, was significantly and substantially attenuated after ~800 ms. This demonstrates that a strong reason to modify the balance control strategy was created and subjects were highly motivated to minimise sway. Despite this, the initial response remained unchanged. This suggests little effect on the feedforward settings of the nervous system responsible for coupling pure vestibular input to functional motor output. The much stronger, later effect can be attributed to an integration of balance-relevant sensory feedback once the body was in motion. These results demonstrate that the feedforward and feedback components of a vestibular-evoked balance response are differently affected by postural threat. Although a fear of falling has previously been linked with instability and even falling itself, our findings suggest that this relationship is not attributable to changes in the feedforward vestibular control of balance. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  17. Postural adaptations to long-term training in Prader-Willi patients

    Science.gov (United States)

    2011-01-01

    Background Improving balance and reducing risk of falls is a relevant issue in Prader-Willi Syndrome (PWS). The present study aims to quantify the effect of a mixed training program on balance in patients with PWS. Methods Eleven adult PWS patients (mean age: 33.8 ± 4.3 years; mean BMI: 43.3 ± 5.9 Kg/m2) attended a 2-week training program including balance exercises during their hospital stay. At discharge, Group 1 (6 patients) continued the same exercises at home for 6 months, while Group 2 (5 patients) quitted the program. In both groups, a low-calorie, well-balanced diet of 1.200 kcal/day was advised. They were assessed at admission (PRE), after 2 weeks (POST1) and at 6-month (POST2). The assessment consisted of a clinical examination, video recording and 60-second postural evaluation on a force platform. Range of center of pressure (CoP) displacement in the antero-posterior direction (RANGEAP index) and the medio-lateral direction (RANGEML index) and its total trajectory length were computed. Results At POST1, no significant changes in all of the postural parameters were observed. At completion of the home program (POST2), the postural assessment did not reveal significant modifications. No changes in BMI were observed in PWS at POST2. Conclusions Our results showed that a long-term mixed, but predominantly home-based training on PWS individuals was not effective in improving balance capacity. Possible causes of the lack of effectiveness of our intervention include lack of training specificity, an inadequate dose of exercise, an underestimation of the neural and sensory component in planning rehabilitation exercise and failed body weight reduction during the training. Also, the physiology of balance instability in these patients may possibly compose a complex puzzle not affected by our exercise training, mainly targeting muscle weakness. PMID:21575153

  18. A flexed posture in elderly patients is associated with impairments in postural control during walking

    NARCIS (Netherlands)

    de Groot, Maartje H.; van der Jagt-Willems, Hanna C.; van Campen, Jos P. C. M.; Lems, Willem F.; Beijnen, Jos H.; Lamoth, Claudine J. C.

    A flexed posture (FP) is characterized by protrusion of the head and an increased thoracic kyphosis (TK), which may be caused by osteoporotic vertebral fractures (VFs). These impairments may affect motor function, and consequently increase the risk of falling and fractures. The aim of the current

  19. A flexed posture in elderly patients is associated with impairments in postural control during walking

    NARCIS (Netherlands)

    de Groot, M.H.; van der Jagt-Willems, H.; van Campen, J.P.C.M.; Lems, W.F.; Beijnen, J.H.; Lamoth, C.J.C.

    2014-01-01

    A flexed posture (FP) is characterized by protrusion of the head and an increased thoracic kyphosis (TK), which may be caused by osteoporotic vertebral fractures (VFs). These impairments may affect motor function, and consequently increase the risk of falling and fractures. The aim of the current

  20. Effects of rapid maxillary expansion on head posture, postural stability, and fall risk

    Directory of Open Access Journals (Sweden)

    Fatih Celebi

    2017-01-01

    Full Text Available Objective: The aim of this study was to investigate the effects of rapid maxillary expansion (RME on head posture, postural stability, and fall risk. Materials and Methods: A sample of 51 adolescent patients was randomly divided into two groups. In the first group, which consisted of 28 patients (15 females and 13 males, RME was performed as a part of routine orthodontic treatment. The remaining 23 individuals (12 females and 11 males served as the control group. Lateral cephalometric radiographs taken in natural head position, postural stability, and fall risk scores were obtained during the first visit. They were repeated on average 3.8 months and 3.5 months later for the study and control groups, respectively. The changes were analyzed using the Wilcoxon signed-rank test, paired samples t-test, Mann–Whitney U-test, and independent samples t-test. Results: As a result of RME, a statistically significant decrease was detected in the fall risk score (P < 0.05 in the study group, while the head position and postural stability remained unchanged. For the control group, no significant changes were observed in all measurements. Conclusions: The result of the present study suggests that RME has a capacity of improving fall risk.

  1. Clinical evaluation of postural posture of patients with previous stroke subjected to early rehabilitation

    Directory of Open Access Journals (Sweden)

    Anna Sagan

    2018-02-01

    Full Text Available Introduction: Impairment disorders are often found in patients with stroke and impairment of motor and cognitive functions. This is a very serious complication because, by imposing a motor impairment, it aggravates the condition of disability and makes it difficult to conduct physical rehabilitation.The resulting neurological deficits due to stroke determine functional disorders. The possibility of locomotion is usually compromised, therefore the risk of falls increases significantly. The aim of the work is to present Postural Assesment Scale for Strock PASS with the postural stroke assessment scale, the impact of early rehabilitation of patients staying in the neurology ward.Material and methods: Postural examination was carried out among 17 people, of which 8 were women, and 9 were male. The study was divided into two stages. The first stage occurred immediately after the stroke and the second one before the patient was discharged from the ward. Research was carried out at the Biegański Specialist Hospital in Grudziądz in the Department of Neurology and Clinical Neuroimmunology and Impact Department.Conclusions: The results of the postural studies carried out in people with previous stroke subjected to early physiotherapy have a beneficial effect of the conducted therapy. There are positive changes between the first and the final examination of the patients.

  2. Chronicle of ion-current instabilities: old and new

    International Nuclear Information System (INIS)

    Landau, R.W.

    1975-07-01

    For counter-streaming ion currents along a uniform magnetic field, a purely growing instability exists with a growth rate as high as 16 times the ion gyrofrequency. When the streaming ions are only 1 percent of the stationary ions, the growth rate is still 4 times the gyrofrequency, but the real part is near the lower hybrid frequency. These instabilities are in addition to the Drummond-Rosenbluth ion mode. Finite β effects increase the growth rate and can be important for β greater than 10 -4 . In all this, T/sub parallel,+/ = T/sub parallel,-/ and T/sub perpendicular to/ = 0. (U.S.)

  3. Postural Hand Synergies during Environmental Constraint Exploitation

    Directory of Open Access Journals (Sweden)

    Cosimo Della Santina

    2017-08-01

    Full Text Available Humans are able to intuitively exploit the shape of an object and environmental constraints to achieve stable grasps and perform dexterous manipulations. In doing that, a vast range of kinematic strategies can be observed. However, in this work we formulate the hypothesis that such ability can be described in terms of a synergistic behavior in the generation of hand postures, i.e., using a reduced set of commonly used kinematic patterns. This is in analogy with previous studies showing the presence of such behavior in different tasks, such as grasping. We investigated this hypothesis in experiments performed by six subjects, who were asked to grasp objects from a flat surface. We quantitatively characterized hand posture behavior from a kinematic perspective, i.e., the hand joint angles, in both pre-shaping and during the interaction with the environment. To determine the role of tactile feedback, we repeated the same experiments but with subjects wearing a rigid shell on the fingertips to reduce cutaneous afferent inputs. Results show the persistence of at least two postural synergies in all the considered experimental conditions and phases. Tactile impairment does not alter significantly the first two synergies, and contact with the environment generates a change only for higher order Principal Components. A good match also arises between the first synergy found in our analysis and the first synergy of grasping as quantified by previous work. The present study is motivated by the interest of learning from the human example, extracting lessons that can be applied in robot design and control. Thus, we conclude with a discussion on implications for robotics of our findings.

  4. Factors that influence soft tissue thickness over the greater trochanter: application to understanding hip fractures.

    Science.gov (United States)

    Levine, Iris C; Minty, Lauren E; Laing, Andrew C

    2015-03-01

    Fall-related hip injuries are a concern for the growing population of older adults. Evidence suggests that soft tissue overlying the greater trochanter attenuates the forces transmitted to the proximal femur during an impact, reducing mechanical risk of hip fracture. However, there is limited information about the factors that influence trochanteric soft tissue thickness. The current study used ultrasonography and electromyography to determine whether trochanteric soft tissue thickness could be quantified reproducibly and whether it was influenced by: (1) gender; (2) hip postures associated with potential falling configurations in the sagittal plane (from 30° of extension to 60° of flexion, at 15° intervals), combined adduction-flexion, and combined adduction-extension; and (3) activation levels of the tensor fascia lata (TFL) and gluteus medius (GM) muscles. Our results demonstrated that soft tissue thickness can be measured reliably in nine hip postures and three muscle activation conditions (for all conditions, ICC >0.98). Mean (SD) thickness in quiet stance was 2.52 cm. Thickness was 27.0% lower for males than females during quiet stance. It was 16.4% greater at maximum flexion than quiet standing, 27.2% greater at maximum extension, and 12.5% greater during combined adduction-flexion. However, there was no significant difference between combined adduction-extension and quiet standing. Thickness was not affected by changes in muscle activity. Forces applied to the femoral neck during a lateral fall decrease as trochanteric soft tissue thickness increases; gender and postural configuration at impact could influence the loads applied to the proximal femur (and thus hip fracture risk) during falls on the hip. © 2014 Wiley Periodicals, Inc.

  5. Interactive effect of body posture on exercise-induced atrial natriuretic peptide release.

    Science.gov (United States)

    Ray, C A; Delp, M D; Hartle, D K

    1990-05-01

    The purpose of this investigation was to test the hypothesis that supine exercise elicits a greater atrial natriuretic peptide (ANP) response than upright exercise because of higher atrial filling pressure attained in the supine posture. Plasma ANP concentration ([ANP]) was measured during continuous graded supine and upright exercise in eight healthy men at rest after 4 min of cycling exercise at 31, 51, and 79% of posture-specific peak oxygen uptake (VO2 peak), after 2 min of cycling at posture-specific VO2 peak, and 5 and 15 min postexercise. [ANP] was significantly increased (P less than 0.05) above rest by 64, 140, and 228% during supine cycling at 51 and 79% and VO2 peak, respectively. During upright cycling, [ANP] was significantly increased (P less than 0.05) at 79% (60%) and VO2 peak (125%). After 15 min of postexercise rest, [ANP] remained elevated (P less than 0.05) only in the supine subjects. [ANP] was 63, 79, and 75% higher (P less than 0.05) in the supine than in the upright position during cycling at 51 and 79% and VO2 peak. Systolic, diastolic, and mean blood pressures were not significantly (P greater than 0.05) different between positions in all measurement periods. Heart rates were lower (P less than 0.05) in the supine position compared with the upright position. In conclusion, these results suggest that supine exercise elicits greater ANP release independent of blood pressure and heart rate but presumably caused by greater venous return, central blood volume, and concomitant atrial filling pressure and stretch.

  6. Safeguards technology: present posture and future impact

    International Nuclear Information System (INIS)

    Keepin, G.R.

    1976-01-01

    With widespread and growing concern over the issues of nuclear safeguards, international nuclear trade and nuclear weapons proliferation, the full development of the world's nuclear energy potential could well depend on how effectively the strategic nuclear materials that fuel nuclear power are controlled and safeguarded. The broad U.S. program in nuclear safeguards and security is directed toward a balanced safeguards system incorporating the two major components of physical security and materials control. The current posture of modern safeguards technology, its impact on plant operations, and the key role it must play in the implementation of stringent cost-effective safeguards systems in facilities throughout the nuclear fuel cycle are outlined

  7. Artificial Intelligence Software for Assessing Postural Stability

    Science.gov (United States)

    Lieberman, Erez; Forth, Katharine; Paloski, William

    2013-01-01

    A software package reads and analyzes pressure distributions from sensors mounted under a person's feet. Pressure data from sensors mounted in shoes, or in a platform, can be used to provide a description of postural stability (assessing competence to deficiency) and enables the determination of the person's present activity (running, walking, squatting, falling). This package has three parts: a preprocessing algorithm for reading input from pressure sensors; a Hidden Markov Model (HMM), which is used to determine the person's present activity and level of sensing-motor competence; and a suite of graphical algorithms, which allows visual representation of the person's activity and vestibular function over time.

  8. Tunnelling instability via perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Graffi, S. (Bologna Univ. (Italy). Dip. di Matematica); Grecchi, V. (Moderna Univ. (Italy). Dip. di Matematica); Jona-Lasinio, G. (Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique et Hautes Energies)

    1984-10-21

    The semiclassical limit of low lying states in a multiwell potential is studied by rigorous perturbative techniques. In particular tunnelling instability and localisation of wave functions is obtained in a simple way under small deformations of symmetric potentials.

  9. Fluctuations and Instability in Sedimentation

    KAUST Repository

    Guazzelli, É lisabeth; Hinch, John

    2011-01-01

    This review concentrates on the fluctuations of the velocities of sedimenting spheres, and on the structural instability of a suspension of settling fibers. For many years, theoretical estimates and numerical simulations predicted the fluctuations

  10. Edge instabilities of topological superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Johannes S. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany); Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Assaad, Fakher F. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany); Schnyder, Andreas P. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2016-07-01

    Nodal topological superconductors display zero-energy Majorana flat bands at generic edges. The flatness of these edge bands, which is protected by time-reversal and translation symmetry, gives rise to an extensive ground state degeneracy and a diverging density of states. Therefore, even arbitrarily weak interactions lead to an instability of the flat-band edge states towards time-reversal and translation-symmetry broken phases, which lift the ground-state degeneracy. Here, we employ Monte Carlo simulations combined with mean-field considerations to examine the instabilities of the flat-band edge states of d{sub xy}-wave superconductors. We find that attractive interactions induce a complex s-wave pairing instability together with a density wave instability. Repulsive interactions, on the other hand, lead to ferromagnetism mixed with spin-triplet pairing at the edge. We discuss the implications of our findings for experiments on cuprate high-temperature superconductors.

  11. Instability of ties in compression

    DEFF Research Database (Denmark)

    Buch-Hansen, Thomas Cornelius

    2013-01-01

    Masonry cavity walls are loaded by wind pressure and vertical load from upper floors. These loads results in bending moments and compression forces in the ties connecting the outer and the inner wall in a cavity wall. Large cavity walls are furthermore loaded by differential movements from...... the temperature gradient between the outer and the inner wall, which results in critical increase of the bending moments in the ties. Since the ties are loaded by combined compression and moment forces, the loadbearing capacity is derived from instability equilibrium equations. Most of them are iterative, since...... exact instability solutions are complex to derive, not to mention the extra complexity introducing dimensional instability from the temperature gradients. Using an inverse variable substitution and comparing an exact theory with an analytical instability solution a method to design tie...

  12. Summary of longitudinal instabilities workshop

    Energy Technology Data Exchange (ETDEWEB)

    Chasman, R.

    1976-01-01

    A five-day ISABELLE workshop on longitudinal instabilities was held at Brookhaven, August 9-13, 1976. About a dozen outside accelerator experts, both from Europe and the U.S.A., joined the local staff for discussions of longitudinal instabilities in ISABELLE. An agenda of talks was scheduled for the first day of the workshop. Later during the week, a presentation was given on the subject ''A more rigorous treatment of Landau damping in longitudinal beam instabilities''. A few progress meetings were held in which disagreements regarding calculations of coupling impedances were clarified. A summary session was held on the last day. Heavy emphasis was put on single bunched beam instabilities in the microwave region extending above the cut-off frequency of the ISABELLE vacuum chamber.

  13. Predicting Catastrophic BGP Routing Instabilities

    National Research Council Canada - National Science Library

    Nguyen, Lien

    2004-01-01

    .... Currently, this critical function is performed by the Border Gateway Protocol (BGP) version 4 RF01771. Like all routing protocols, BGP is vulnerable to instabilities that reduce its effectiveness...

  14. WELLBORE INSTABILITY: CAUSES AND CONSEQUENCES

    Directory of Open Access Journals (Sweden)

    Borivoje Pašić

    2007-12-01

    Full Text Available Wellbore instability is one of the main problems that engineers meet during drilling. The causes of wellbore instability are often classified into either mechanical (for example, failure of the rock around the hole because of high stresses, low rock strength, or inappropriate drilling practice or chemical effects which arise from damaging interaction between the rock, generally shale, and the drilling fluid. Often, field instances of instability are a result of a combination of both chemical and mechanical. This problem might cause serious complication in well and in some case can lead to expensive operational problems. The increasing demand for wellbore stability analyses during the planning stage of a field arise from economic considerations and the increasing use of deviated, extended reach and horizontal wells. This paper presents causes, indicators and diagnosing of wellbore instability as well as the wellbore stresses model.

  15. Cardiovascular responses to postural changes: differences with age for women and men

    Science.gov (United States)

    Frey, M. A.; Tomaselli, C. M.; Hoffler, W. G.

    1994-01-01

    The cardiovascular responses to postural change, and how they are affected by aging, are inadequately described in women. Therefore, the authors examined the influence of age and sex on the responses of blood pressure, cardiac output, heart rate, and other variables to change in posture. Measurements were made after 10 minutes each in the supine, seated, and standing positions in 22 men and 25 women who ranged in age from 21 to 59 years. Several variables differed, both by sex and by age, when subjects were supine. On rising, subjects' diastolic and mean arterial pressures, heart rate, total peripheral resistance (TPR), and thoracic impedance increased; cardiac output, stroke volume, and mean stroke ejection rate decreased; and changes in all variables, except heart rate, were greater from supine to sitting than sitting to standing. The increase in heart rate was greater in the younger subjects, and increases in TPR and thoracic impedance were greater in the older subjects. Stroke volume decreased less, and TPR and thoracic impedance increased more, in the women than in the men. The increase in TPR was particularly pronounced in the older women. These studies show that the cardiovascular responses to standing differ, in some respects, between the sexes and with age. The authors suggest that the sex differences are, in part, related to greater decrease of thoracic blood volume with standing in women than in men, and that the age differences result, in part, from decreased responsiveness of the high-pressure baroreceptor system.

  16. Genomic instability and radiation effects

    International Nuclear Information System (INIS)

    Christian Streffer

    2007-01-01

    Complete text of publication follows. Cancer, genetic mutations and developmental abnormalities are apparently associated with an increased genomic instability. Such phenomena have been frequently shown in human cancer cells in vitro and in situ. It is also well-known that individuals with a genetic predisposition for cancer proneness, such as ataxia telangiectesia, Fanconi anaemia etc. demonstrate a general high genomic instability e.g. in peripheral lymphocytes before a cancer has developed. Analogous data have been found in mice which develop a specific congenital malformation which has a genetic background. Under these aspects it is of high interest that ionising radiation can increase the genomic instability of mammalian cells after exposures in vitro an in vivo. This phenomenon is expressed 20 to 40 cell cycles after the exposure e.g. by de novo chromosomal aberrations. Such effects have been observed with high and low LET radiation, high LET radiation is more efficient. With low LET radiation a good dose response is observed in the dose range 0.2 to 2.0 Gy, Recently it has been reported that senescence and genomic instability was induced in human fibroblasts after 1 mGy carbon ions (1 in 18 cells are hit), apparently bystander effects also occurred under these conditions. The instability has been shown with DNA damage, chromosomal aberrations, gene mutation and cell death. It is also transferred to the next generation of mice with respect to gene mutations, chromosomal aberrations and congenital malformations. Several mechanisms have been discussed. The involvement of telomeres has gained interest. Genomic instability seems to be induced by a general lesion to the whole genome. The transmission of one chromosome from an irradiated cell to an non-irradiated cell leads to genomic instability in the untreated cells. Genomic instability increases mutation rates in the affected cells in general. As radiation late effects (cancer, gene mutations and congenital

  17. Falls efficacy, postural balance, and risk for falls in older adults with falls-related emergency department visits: prospective cohort study.

    Science.gov (United States)

    Pua, Yong-Hao; Ong, Peck-Hoon; Clark, Ross Allan; Matcher, David B; Lim, Edwin Choon-Wyn

    2017-12-21

    Risk for falls in older adults has been associated with falls efficacy (self-perceived confidence in performing daily physical activities) and postural balance, but available evidence is limited and mixed. We examined the interaction between falls efficacy and postural balance and its association with future falls. We also investigated the association between falls efficacy and gait decline. Falls efficacy, measured by the Modified Falls Efficacy Scale (MFES), and standing postural balance, measured using computerized posturography on a balance board, were obtained from 247 older adults with a falls-related emergency department visit. Six-month prospective fall rate and habitual gait speed at 6 months post baseline assessment were also measured. In multivariable proportional odds analyses adjusted for potential confounders, falls efficacy modified the association between postural balance and fall risk (interaction P = 0.014): increasing falls efficacy accentuated the increased fall risk related to poor postural balance. Low baseline falls efficacy was strongly predictive of worse gait speed (0.11 m/s [0.06 to 0.16] slower gait speed per IQR decrease in MFES; P falls efficacy but poor postural balance were at greater risk for falls than those with low falls efficacy; however, low baseline falls efficacy was strongly associated with worse gait function at follow-up. Further research into these subgroups of older adults is warranted. ClinicalTrials.gov identifier: NCT01713543 .

  18. Postural changes in obese and non-obese children and adolescents. 10.5007/1980-0037.2011v13n6p448

    Directory of Open Access Journals (Sweden)

    Larissa Rosa da Silva

    2011-11-01

    Full Text Available Obesity has reached epidemic proportions over recent years and is related to cardiovascular risk factors, as well as to the occurrence of postural changes in adults, children and adolescents. The objective of this study was to identify the prevalence of postural abnormalities and pain in schoolchildren. Fifty-one children and adolescents of both genders aged 9-17 years were divided into an obese (n = 33 and a non-obese group (n = 18. Weight and height were measured to calculate the body mass index. A questionnaire was used to assess the presence or absence of pain. Postural deviations of the shoulder, head and knees were analyzed by photometry using the Corel Draw12 software for the determination of angular measures and size. Obese boys showed greater postural changes in the region of the knees than non-obese ones (p<0.001. No significant differences in any of the regions analyzed were observed for girls. On the other hand, the prevalence of pain was significantly higher among obese girls than among non-obese girls. We conclude that postural changes are not limited to obese children, but excess weight may increase this deviation. Further studies are needed to diagnose these changes during childhood in order to permit early intervention and good posture in adult life.

  19. Postural changes in obese and non-obese children and adolescents.DOI:10.5007/1980-0037.2011v13n6p448

    Directory of Open Access Journals (Sweden)

    Larissa Rosa da Silva

    2011-11-01

    Full Text Available Obesity has reached epidemic proportions over recent years and is related to cardiovascular risk factors, as well as to the occurrence of postural changes in adults, children and adolescents. The objective of this study was to identify the prevalence of postural abnormalities and pain in schoolchildren. Fifty-one children and adolescents of both genders aged 9-17 years were divided into an obese (n = 33 and a non-obese group (n = 18. Weight and height were measured to calculate the body mass index. A questionnaire was used to assess the presence or absence of pain. Postural deviations of the shoulder, head and knees were analyzed by photometry using the Corel Draw12 software for the determination of angular measures and size. Obese boys showed greater postural changes in the region of the knees than non-obese ones (p<0.001. No significant differences in any of the regions analyzed were observed for girls. On the other hand, the prevalence of pain was significantly higher among obese girls than among non-obese girls. We conclude that postural changes are not limited to obese children, but excess weight may increase this deviation. Further studies are needed to diagnose these changes during childhood in order to permit early intervention and good posture in adult life.

  20. The influence of computer use on the sitting posture of high school students who develop neck and shoulder pain

    Directory of Open Access Journals (Sweden)

    Y. Brink

    2009-02-01

    Full Text Available The prevalence of neck and shoulder pain (NSP is increas-ing in adolescents and is related to increased time spent on computers.The influence of sitting posture on the development of computer-relatedNSP among adolescents is unclear. This study investigated how the sittingposture of the upper quadrant changes over a ten minute period ofcomputer use in once asymptomatic adolescents who later developed NSP.M ethod: Sitting alignment was measured using the Photographic PostureA nalysis Method. The students performed a typing task while two con -secutive photographs were taken ten minutes apart. The students werefollowed for six months and the photographs of those who developed NSPw ere analy z ed.R esults: The results show that there is no significant change in sitting posture over time. Observationally the most common pattern was to move from a more flexed posture to a more upright posture and there were greater posturalchanges in the case group (students with extreme cervical angles compared to the control group (students with thepreferred cervical ROM (34.75º - 43.95º, although both findings were not statistically significant.Conclusion: There was no change, over a ten minute period, in the sitting posture of computing high school studentswho developed computer-related NSP after six months therefore students should be encouraged to avoid monotonoussitting in front of computers because this could be associated with NSP.

  1. Aerodynamic instability: A case history

    Science.gov (United States)

    Eisenmann, R. C.

    1985-01-01

    The identification, diagnosis, and final correction of complex machinery malfunctions typically require the correlation of many parameters such as mechanical construction, process influence, maintenance history, and vibration response characteristics. The progression is reviewed of field testing, diagnosis, and final correction of a specific machinery instability problem. The case history presented addresses a unique low frequency instability problem on a high pressure barrel compressor. The malfunction was eventually diagnosed as a fluidic mechanism that manifested as an aerodynamic disturbance to the rotor assembly.

  2. Surgical treatment of chest instability

    International Nuclear Information System (INIS)

    Kitka, M.; Masek, M.

    2015-01-01

    Fractures of the ribs is the most common thoracic injury after blunt trauma. Chest wall instability (flail chest) is a common occurrence in the presence of multiple ribs fracture. Unilateral or bilateral fractures more ribs anteriorly or posteriorly will produce enough instability that paradoxical respiratory motion results in hypoventilation of an unacceptable degree. Open approach and surgical stabilisation of the chest preserved pulmonary function, improved pain control, minimized posttraumatic deformities and shorter back to work time. (author)

  3. Beam Instabilities in Hadron Synchrotrons

    CERN Document Server

    Métral, E; Bartosik, H; Biancacci, N; Buffat, X; Esteban Muller, J F; Herr, W; Iadarola, G; Lasheen, A; Li, K; Oeftiger, A; Pieloni, T; Quartullo, D; Rumolo, G; Salvant, B; Schenk, M; Shaposhnikova, E; Tambasco, C; Timko, H; Zannini, C; Burov, A; Banfi, D; Barranco, J; Mounet, N; Boine-Frankenheim, O; Niedermayer, U; Kornilov, V; White, S

    2016-01-01

    Beam instabilities cover a wide range of effects in particle accelerators and they have been the subjects of intense research for several decades. As the machines performance was pushed new mechanisms were revealed and nowadays the challenge consists in studying the interplays between all these intricate phenomena, as it is very often not possible to treat the different effects separately. The aim of this paper is to review the main mechanisms, discussing in particular the recent developments of beam instability theories and simulations.

  4. Microsatellite instability in bladder cancer

    DEFF Research Database (Denmark)

    Gonzalez-Zulueta, M; Ruppert, J M; Tokino, K

    1993-01-01

    Somatic instability at microsatellite repeats was detected in 6 of 200 transitional cell carcinomas of the bladder. Instabilities were apparent as changes in (GT)n repeat lengths on human chromosome 9 for four tumors and as alterations in a (CAG)n repeat in the androgen receptor gene on the X...... or larger (> 2 base pairs) alterations in repeat length. All six tumors were low stage (Ta-T1), suggesting that these alterations can occur early in bladder tumorigenesis....

  5. Waves and instabilities in plasmas

    International Nuclear Information System (INIS)

    Chen, L.

    1987-01-01

    The contents of this book are: Plasma as a Dielectric Medium; Nyquist Technique; Absolute and Convective Instabilities; Landau Damping and Phase Mixing; Particle Trapping and Breakdown of Linear Theory; Solution of Viasov Equation via Guilding-Center Transformation; Kinetic Theory of Magnetohydrodynamic Waves; Geometric Optics; Wave-Kinetic Equation; Cutoff and Resonance; Resonant Absorption; Mode Conversion; Gyrokinetic Equation; Drift Waves; Quasi-Linear Theory; Ponderomotive Force; Parametric Instabilities; Problem Sets for Homework, Midterm and Final Examinations

  6. Task-related and person-related variables influence the effect of low back pain on anticipatory postural adjustments.

    Science.gov (United States)

    Jacobs, Jesse V; Lyman, Courtney A; Hitt, Juvena R; Henry, Sharon M

    2017-08-01

    People with low back pain exhibit altered postural coordination that has been suggested as a target for treatment, but heterogeneous presentation has rendered it difficult to identify appropriate candidates and protocols for such treatments. This study evaluated the associations of task-related and person-related factors with the effect of low back pain on anticipatory postural adjustments. Thirteen subjects with and 13 without low back pain performed seated, rapid arm flexion in self-initiated and cued conditions. Mixed-model ANOVA were used to evaluate group and condition effects on APA onset latencies of trunk muscles, arm-raise velocity, and pre-movement cortical potentials. These measures were evaluated for correlation with pain ratings, Fear Avoidance Beliefs Questionnaire scores, and Modified Oswestry Questionnaire scores. Delayed postural adjustments of subjects with low back pain were greater in the cued condition than in the self-initiated condition. The group with low back pain exhibited larger-amplitude cortical potentials than the group without pain, but also significantly slower arm-raise velocities. With arm-raise velocity as a covariate, the effect of low back pain remained significant for the latencies of postural adjustments but not for cortical potentials. Latencies of the postural adjustments significantly correlated with Oswestry and Fear Avoidance Beliefs scores. Delayed postural adjustments with low back pain appear to be influenced by cueing of movement, pain-related disability and fear of activity. These results highlight the importance of subject characteristics, task condition, and task performance when comparing across studies or when developing treatment of people with low back pain. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Instability of enclosed horizons

    Science.gov (United States)

    Kay, Bernard S.

    2015-03-01

    We point out that there are solutions to the scalar wave equation on dimensional Minkowski space with finite energy tails which, if they reflect off a uniformly accelerated mirror due to (say) Dirichlet boundary conditions on it, develop an infinite stress-energy tensor on the mirror's Rindler horizon. We also show that, in the presence of an image mirror in the opposite Rindler wedge, suitable compactly supported arbitrarily small initial data on a suitable initial surface will develop an arbitrarily large stress-energy scalar near where the two horizons cross. Also, while there is a regular Hartle-Hawking-Israel-like state for the quantum theory between these two mirrors, there are coherent states built on it for which there are similar singularities in the expectation value of the renormalized stress-energy tensor. We conjecture that in other situations with analogous enclosed horizons such as a (maximally extended) Schwarzschild black hole in equilibrium in a (stationary spherical) box or the (maximally extended) Schwarzschild-AdS spacetime, there will be similar stress-energy singularities and almost-singularities—leading to instability of the horizons when gravity is switched on and matter and gravity perturbations are allowed for. All this suggests it is incorrect to picture a black hole in equilibrium in a box or a Schwarzschild-AdS black hole as extending beyond the past and future horizons of a single Schwarzschild (/Schwarzschild-AdS) wedge. It would thus provide new evidence for 't Hooft's brick wall model while seeming to invalidate the picture in Maldacena's ` Eternal black holes in AdS'. It would thereby also support the validity of the author's matter-gravity entanglement hypothesis and of the paper ` Brick walls and AdS/CFT' by the author and Ortíz.

  8. Influence of Functional Head Postures on the Dynamic Functional ...

    African Journals Online (AJOL)

    Background: The dentist utilizes supine position during therapeutic procedures, while the patients assumes extended head posture during mastication. It is critical for the restorative dentist to evaluate and understand the possible effect of change in head posture on occlusal contacts. An understanding of the possible effect ...

  9. Effects of Dyslexia on Postural Control in Adults

    Science.gov (United States)

    Patel, M.; Magnusson, M.; Lush, D.; Gomez, S.; Fransson, P. A.

    2010-01-01

    Dyslexia has been shown to affect postural control. The aim of the present study was to investigate the difference in postural stability measured as torque variance in an adult dyslexic group (n=14, determined using the Adult Dyslexia Checklist (ADCL) and nonsense word repetition test) and an adult non-dyslexic group (n=39) on a firm surface and…

  10. Characterization of postural control impairment in women with fibromyalgia

    Science.gov (United States)

    Sempere-Rubio, Núria; López-Pascual, Juan; Aguilar-Rodríguez, Marta; Cortés-Amador, Sara; Espí-López, Gemma; Villarrasa-Sapiña, Israel

    2018-01-01

    The main goal of this cross-sectional study was to detect whether women with fibromyalgia syndrome (FMS) have altered postural control and to study the sensory contribution to postural control. We also explored the possibility that self-induced anxiety and lower limb strength may be related to postural control. For this purpose, 129 women within an age range of 40 to 70 years were enrolled. Eighty of the enrolled women had FMS. Postural control variables, such as Ellipse, Root mean square (RMS) and Sample entropy (SampEn), in both directions (i.e. mediolateral and anteroposterior), were calculated under five different conditions. A force plate was used to register the center of pressure shifts. Furthermore, isometric lower limb strength was recorded with a portable dynamometer and normalized by lean body mass. The results showed that women with FMS have impaired postural control compared with healthy people, as they presented a significant increase in Ellipse and RMS values (pPostural control also worsens with the gradual alteration of sensory inputs in this population (p0.05). There were no significant correlations between postural control and lower limb strength (p>0.05). Therefore, women with FMS have impaired postural control that is worse when sensory inputs are altered but is not correlated with their lower limb strength. PMID:29723223

  11. Thoracic posture, shoulder muscle activation patterns and isokinetic ...

    African Journals Online (AJOL)

    Poor posture, scapular dyskinesia, altered scapular muscle recruitment patterns and ... postural deviation and incorrect shoulder kinematics.[5]. Knowledge of the .... the contra-lateral hand was placed as far down the spinal column as possible, and the ... produced by muscle contraction for rotation around a joint.[12] During.

  12. The final common pathway in postural control - Developmental perspective

    NARCIS (Netherlands)

    Kernell, D

    A brief review is given concerning postural specialisations among mammalian muscle fibres and motor units. Most skeletal muscles contain a mixture of fibres with different characteristics, and their slow-twitch (S) units are well-known to possess properties suitable for postural tasks: they are

  13. Effect of magnification loupes on dental hygiene student posture.

    Science.gov (United States)

    Maillet, J Peggy; Millar, A Michele; Burke, Jillian M; Maillet, Michelle A; Maillet, Wayne A; Neish, Nancy R

    2008-01-01

    The chair-side work posture of dental hygienists has long been a concern because of health-related problems potentially caused or exacerbated by poor posture. The purpose of this study was to investigate if using magnification loupes improved dental hygiene students' posture during provision of treatment. The treatment chosen was hand-scaling, and the effect of the timing of introduction of the loupes to students was also examined. Thirty-five novice dental hygiene students took part in the study. Each student was assessed providing dental hygiene care with and without loupes, thus controlling for innate differences in natural posture. Students were randomized into two groups. Group one used loupes in the first session and did not use them for the second session. Group two reversed this sequence. At the end of each session, all students were videotaped while performing scaling procedures. Their posture was assessed using an adapted version of Branson et al.'s Posture Assessment Instrument (PAI). Four raters assessed students at three time periods for nine posture components on the PAI. A paired t-test compared scores with and without loupes for each student. Scores showed a significant improvement in posture when using loupes (ppostural benefit is realized by requiring students to master the use of magnification loupes as early as possible within the curriculum.

  14. Problems of display postures in the Charadrii (Aves: Charadriiformes)

    African Journals Online (AJOL)

    Studies of displays in the Charadrii (= waders or shorebirds) show that the same posture in different species, even quite closely related, may have a different function in a given context. As a corollary to this, two species even in the same genus may have quite different display postures to convey the same message.

  15. Differences in body composition and prevalence for postural ...

    African Journals Online (AJOL)

    The aim of this study is to compare the prevalence rate for postural deviations and body composition status among two racial groups in South Africa. The sample (n = 216) consisted of 89 African girls and 127 Caucasian girls. Anthropometric (BMI and percentage body fat) and body posture measurements were performed.

  16. Posture and isokinetic shoulder strength in female water polo players

    African Journals Online (AJOL)

    Background: Being overhead athletes, water polo players can present with muscular imbalances of the shoulder, between the internal rotators (IR) and external rotators (ER), leading to changes in posture and an increased risk of injury. Objectives: To assess posture and isokinetic shoulder strength of female club-level ...

  17. Prism adaptation improves postural imbalance in neglect patients

    NARCIS (Netherlands)

    Nijboer, Tanja C W; Olthoff, Liselot; Van der Stigchel, Stefan; Visser-Meily, Johanna M a

    2014-01-01

    Several studies have found a negative relation between neglect and postural imbalance. The aim of the current study was to investigate the influence of a single session of prism adaptation on balance [i.e. mediolateral and anteroposterior center of pressure (CoP)] and postural sway (i.e. mean

  18. Predictors of Postural Stability in Children with ADHD

    Science.gov (United States)

    Ghanizadeh, Ahmad

    2011-01-01

    Objective: As children with ADHD who have more inattention problems are more frequently with fine motor problems, it is not clear whether postural balance problems are associated with different subtypes of ADHD. This study investigates the predictors of postural stability in children with ADHD considering the covariant factors of age, gender, and…

  19. Age-related differences in norepinephrine kinetics: Effect of posture and sodium-restricted diet

    International Nuclear Information System (INIS)

    Supiano, M.A.; Linares, O.A.; Smith, M.J.; Halter, J.B.

    1990-01-01

    We used compartmental analysis to study the influence of age on the kinetics of norepinephrine (NE) distribution and metabolism. Plasma NE and [3H]NE levels were measured in 10 young (age 19-33 yr) and 13 elderly (age 62-73 yr) subjects in the basal supine position, during upright posture, and after 1 wk of a sodium-restricted diet. We found that the basal supine release rate of NE into the extravascular compartment, which is the site of endogenous NE release (NE2), was significantly increased in the elderly group (young, 9.6 +/- 0.5; elderly, 12.3 +/- 0.8 nmol.min-1.m-2; means +/- SE; P = 0.016), providing direct evidence for an age-related increase in sympathetic nervous system (SNS) tone. Although upright posture led to a greater increase in plasma NE in the young (0.90 +/- 0.07 to 2.36 +/- 0.16 nM) than in the elderly (1.31 +/- 0.11 to 2.56 +/- 0.31 nM; age group-posture interaction, P = 0.02), the increase in NE2 was similar between the young (9.6 +/- 0.6 to 16.2 +/- 1.5 nmol.min-1.m-2) and the elderly (11.6 +/- 1.4 to 16.1 +/- 2.4 nmol.min-1.m-2; posture effect, P = 0.001; age group-posture interaction, P = 0.15). Thus the increase in SNS tone resulting from upright posture was similar in young and elderly subjects. Plasma NE levels increased similarly in both groups after a sodium-restricted diet (diet effect, P = 0.001; age group-diet interaction, P = 0.23). However, NE2 did not increase significantly in either group (diet effect, P = 0.26), suggesting that SNS tone did not increase after a sodium-restricted diet. Compartmental analysis provides a description of age-related differences in NE kinetics, including an age-related increase in the extravascular NE release rate

  20. History of shoulder instability surgery.

    Science.gov (United States)

    Randelli, Pietro; Cucchi, Davide; Butt, Usman

    2016-02-01

    The surgical management of shoulder instability is an expanding and increasingly complex area of study within orthopaedics. This article describes the history and evolution of shoulder instability surgery, examining the development of its key principles, the currently accepted concepts and available surgical interventions. A comprehensive review of the available literature was performed using PubMed. The reference lists of reviewed articles were also scrutinised to ensure relevant information was included. The various types of shoulder instability including anterior, posterior and multidirectional instability are discussed, focussing on the history of surgical management of these topics, the current concepts and the results of available surgical interventions. The last century has seen important advancements in the understanding and treatment of shoulder instability. The transition from open to arthroscopic surgery has allowed the discovery of previously unrecognised pathologic entities and facilitated techniques to treat these. Nevertheless, open surgery still produces comparable results in the treatment of many instability-related conditions and is often required in complex or revision cases, particularly in the presence of bone loss. More high-quality research is required to better understand and characterise this spectrum of conditions so that successful evidence-based management algorithms can be developed. IV.

  1. Ionospheric modification and parametric instabilities

    International Nuclear Information System (INIS)

    Fejer, J.A.

    1979-01-01

    Thresholds and linear growth rates for stimulated Brillouin and Raman scattering and for the parametric decay instability are derived by using arguments of energy transfer. For this purpose an expression for the ponderomotive force is derived. Conditions under which the partial pressure force due to differential dissipation exceeds the ponderomotive force are also discussed. Stimulated Brillouin and Raman scattering are weakly excited by existing incoherent backscatter radars. The parametric decay instability is strongly excited in ionospheric heating experiments. Saturation theories of the parametric decay instability are therefore described. After a brief discussion of the purely growing instability the effect of using several pumps is discussed as well as the effects of inhomogenicity. Turning to detailed theories of ionospheric heating, artificial spread F is discussed in terms of a purely growing instability where the nonlinearity is due to dissipation. Field-aligned short-scale striations are explained in terms of dissipation of the parametrically excited Langmuir waves (plasma oscillations): they might be further amplified by an explosive instability (except the magnetic equator). Broadband absorption is probably responsible for the 'overshoot' effect: the initially observed level of parametrically excited Langmuir waves is much higher than the steady state level

  2. Relationship between posterior crossbite and postural alterations in children

    Directory of Open Access Journals (Sweden)

    Juliana Jaqueline de Matos Lopes

    2009-12-01

    Full Text Available Objective: To evaluate the posture of individuals with functional posterior crossbite, malocclusion is one of the most in need of orthodontic treatment. Methods: This work presents an analysis of postural among children 6 to 12 years who present functional posterior cross bite of both genders who are in mixed dentition or no intervention prior orthodontic and orthopedic. Was obtained images in the plans: front and back where it was analyzed the asymmetry or symmetry of the individual in the image and in the lateral, anterior, a posterior or normality. Results: 100% had some kind of postural change, and the asymmetry between the scapulae (shoulder found the greatest change, as one of extreme importance in this age group represents a growing skeletal muscle. Conclusion: analyzes all of the children showed postural abnormalities and malocclusion are also of great importance not only to be treating the problem orally, but the postural problem with the help of a multidisciplinary team.

  3. Barnacle geese achieve significant energetic savings by changing posture.

    Directory of Open Access Journals (Sweden)

    Peter G Tickle

    Full Text Available Here we report the resting metabolic rate in barnacle geese (Branta leucopsis and provide evidence for the significant energetic effect of posture. Under laboratory conditions flow-through respirometry together with synchronous recording of behaviour enabled a calculation of how metabolic rate varies with posture. Our principal finding is that standing bipedally incurs a 25% increase in metabolic rate compared to birds sitting on the ground. In addition to the expected decrease in energy consumption of hindlimb postural muscles when sitting, we hypothesise that a change in breathing mechanics represents one potential mechanism for at least part of the observed difference in energetic cost. Due to the significant effect of posture, future studies of resting metabolic rates need to take into account and/or report differences in posture.

  4. Barnacle geese achieve significant energetic savings by changing posture.

    Science.gov (United States)

    Tickle, Peter G; Nudds, Robert L; Codd, Jonathan R

    2012-01-01

    Here we report the resting metabolic rate in barnacle geese (Branta leucopsis) and provide evidence for the significant energetic effect of posture. Under laboratory conditions flow-through respirometry together with synchronous recording of behaviour enabled a calculation of how metabolic rate varies with posture. Our principal finding is that standing bipedally incurs a 25% increase in metabolic rate compared to birds sitting on the ground. In addition to the expected decrease in energy consumption of hindlimb postural muscles when sitting, we hypothesise that a change in breathing mechanics represents one potential mechanism for at least part of the observed difference in energetic cost. Due to the significant effect of posture, future studies of resting metabolic rates need to take into account and/or report differences in posture.

  5. A comparison of the posture between young female handball players and non-training peers.

    Science.gov (United States)

    Grabara, Małgorzata

    2014-01-01

    To evaluate and compare the posture in young female handball players and a group of non-training peers. 125 handball players and 135 non-training individuals as a control group. All the subjects were aged 12-15. Measurements of basic somatic parameters (body height and mass, BMI, fat mass and total body water) were taken with an electronic balance 'Tanita'. The posture was evaluated using the moiré method. We analysed the shape of the spine in the sagittal plane and the position of the spine, pelvis and shoulder girdle in terms of symmetry. In 13-year-old handball players there was a smaller inclination of the thoracolumbar segment and a greater forward tilt of the torso. Among the training 15-year-olds, the inclination of the lower back, the sum of angles of anteroposterior curvatures and the angle of lumbar lordosis were smaller than in their non-training peers. Moreover, a correct pelvic alignment in the frontal plane, and pelvis and scapulas asymmetries in the transverse plane were more common in handball players. The formation of anteroposterior curvatures of the spine diversified some of the age groups of training and non-training young females. Handball training can affect the quality of posture.

  6. Saccadic Eye Movement Improves Plantar Sensation and Postural Balance in Elderly Women.

    Science.gov (United States)

    Bae, Youngsook

    2016-06-01

    Vision, proprioception and plantar sensation contribute to the control of postural balance (PB). Reduced plantar sensation alters postural response and is at an increased risk of fall, and eye movements reduce the postural sway. Therefore, the aim of this study was to study the improvement of plantar sensation and PB after saccadic eye movement (SEM) and pursuit eye movement (PEM) in community-dwelling elderly women. Participants (104 females; 75.11 ± 6.25 years) were randomly allocated into the SEM group (n = 52) and PEM groups (n = 52). The SEM group performed eye fixation and SEM for 5 minutes, and the PEM group performed eye fixation and PEM for 5 minutes. The plantar sensation was measured according to the plantar surface area of the feet in contact with the floor surface before and after the intervention. Before and after SEM and PEM with the eyes open and closed, PB was measured as the area (mm(2)), length (cm), and velocity (cm/s) of the fluctuation of the center of pressure (COP). The plantar sensation of both feet improved in both groups (p eye open and close in both groups (p < 0.01). The length and velocity of the COP significantly decreased in the SEM group compared to the PEM group (p < 0.05). In conclusion, SEM and PEM are effective interventions for improving plantar sensation and PB in elderly women, with greater PB improvement after SEM.

  7. Vibration-enhanced posture stabilization achieved by tactile supplementation: may blind individuals get extra benefits?

    Science.gov (United States)

    Magalhães, Fernando Henrique; Kohn, André Fabio

    2011-08-01

    Diminished balance ability poses a serious health risk due to the increased likelihood of falling, and impaired postural stability is significantly associated with blindness and poor vision. Noise stimulation (by improving the detection of sub-threshold somatosensory information) and tactile supplementation (i.e., additional haptic information provided by an external contact surface) have been shown to improve the performance of the postural control system. Moreover, vibratory noise added to the source of tactile supplementation (e.g., applied to a surface that the fingertip touches) has been shown to enhance balance stability more effectively than tactile supplementation alone. In view of the above findings, in addition to the well established consensus that blind subjects show superior abilities in the use of tactile information, we hypothesized that blind subjects may take extra benefits from the vibratory noise added to the tactile supplementation and hence show greater improvements in postural stability than those observed for sighted subjects. If confirmed, this hypothesis may lay the foundation for the development of noise-based assistive devices (e.g., canes, walking sticks) for improving somatosensation and hence prevent falls in blind individuals. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Diabetic Foot and Exercise Therapy: Step by Step The Role of Rigid Posture and Biomechanics Treatment

    Science.gov (United States)

    Francia, Piergiorgio; Gulisano, Massimo; Anichini, Roberto; Seghieri, Giuseppe

    2014-01-01

    Lower extremity ulcers represent a serious and costly complication of diabetes mellitus. Many factors contribute to the development of diabetic foot. Peripheral neuropathy and peripheral vascular disease are the main causes of foot ulceration and contribute in turn to the growth of additional risk factors such as limited joint mobility, muscular alterations and foot deformities. Moreover, a deficit of balance, posture and biomechanics can be present, in particular in patients at high risk for ulceration. The result of this process may be the development of a vicious cycle which leads to abnormal distribution of the foot's plantar pressures in static and dynamic postural conditions. This review shows that some of these risk factors significantly improve after a few weeks of exercise therapy (ET) intervention. Accordingly it has been suggested that ET can be an important weapon in the prevention of foot ulcer. The aim of ET can relate to one or more alterations typically found in diabetic patients, although greater attention should be paid to the evaluation and possible correction of body balance, rigid posture and biomechanics. Some of the most important limitations of ET are difficult access to therapy, patient compliance and the transitoriness of the results if the training stops. Many proposals have been made to overcome such limitations. In particular, it is important that specialized centers offer the opportunity to participate in ET and during the treatment the team should work to change the patient’s lifestyle by improving the execution of appropriate daily physical activity. PMID:24807636

  9. Visual tasks and postural sway in children with and without autism spectrum disorders.

    Science.gov (United States)

    Chang, Chih-Hui; Wade, Michael G; Stoffregen, Thomas A; Hsu, Chin-Yu; Pan, Chien-Yu

    2010-01-01

    We investigated the influences of two different suprapostural visual tasks, visual searching and visual inspection, on the postural sway of children with and without autism spectrum disorder (ASD). Sixteen ASD children (age=8.75±1.34 years; height=130.34±11.03 cm) were recruited from a local support group. Individuals with an intellectual disability as a co-occurring condition and those with severe behavior problems that required formal intervention were excluded. Twenty-two sex- and age-matched typically developing (TD) children (age=8.93±1.39 years; height=133.47±8.21 cm) were recruited from a local public elementary school. Postural sway was recorded using a magnetic tracking system (Flock of Birds, Ascension Technologies, Inc., Burlington, VT). Results indicated that the ASD children exhibited greater sway than the TD children. Despite this difference, both TD and ASD children showed reduced sway during the search task, relative to sway during the inspection task. These findings replicate those of Stoffregen et al. (2000), Stoffregen, Giveans, et al. (2009), Stoffregen, Villard, et al. (2009) and Prado et al. (2007) and extend them to TD children as well as ASD children. Both TD and ASD children were able to functionally modulate postural sway to facilitate the performance of a task that required higher perceptual effort. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Sensory modulation of movement, posture and locomotion.

    Science.gov (United States)

    Saradjian, A H

    2015-11-01

    During voluntary movement, there exists a well known functional sensory attenuation of afferent inputs, which allows us to discriminate between information related to our own movements and those arising from the external environment. This attenuation or 'gating' prevents some signals from interfering with movement elaboration and production. However, there are situations in which certain task-relevant sensory inputs may not be gated. This review begins by identifying the prevalent findings in the literature with specific regard to the somatosensory modality, and reviews the many cases of classical sensory gating phenomenon accompanying voluntary movement and their neural basis. This review also focuses on the newer axes of research that demonstrate that task-specific sensory information may be disinhibited or even facilitated during engagement in voluntary actions. Finally, a particular emphasis will be placed on postural and/or locomotor tasks involving strong somatosensory demands, especially for the setting of the anticipatory postural adjustments observed prior the initiation of locomotion. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  11. Posture of the head and pharyngeal swallowing

    International Nuclear Information System (INIS)

    Ekberg, O.

    1986-01-01

    Closure of the laryngeal vestibule during swallowing is important for protection of the airways. The present investigation included 53 patients with dysphagia examined cineradiographically with the head held in resting posture, flexion and extension. The ability to protect the airways by the downward movement of the epiglottis and by obliteration of the laryngeal vestibule was studied in different postures of the head. Of 35 patients with normal laryngeal obliteration with the head in resting position 10 showed a defective closure at swallowing in extension. In 18 patients with defective closure of the laryngeal vestibule in resting position 9 were improved on flexion and two on extension of the head. In one patient with defectie closure of the laryngeal vestibule in resting position swallowing in flexion showed an aggravated dysfunction. In our other patients the defective closure became more marked on extension. Four patients had less effective downward movement of the epiglottis with the head in extension. Of 10 patients with defective epiglottic movement with the head in resting position two were improved on tilting the head forwards. The results show that the position of the head influences the closure of the airways during swallowing. Patients with defective protection of the laryngeal vestibule should be instructed to swallow with the head tilted forwards. (orig.)

  12. Self versus environment motion in postural control.

    Directory of Open Access Journals (Sweden)

    Kalpana Dokka

    2010-02-01

    Full Text Available To stabilize our position in space we use visual information as well as non-visual physical motion cues. However, visual cues can be ambiguous: visually perceived motion may be caused by self-movement, movement of the environment, or both. The nervous system must combine the ambiguous visual cues with noisy physical motion cues to resolve this ambiguity and control our body posture. Here we have developed a Bayesian model that formalizes how the nervous system could solve this problem. In this model, the nervous system combines the sensory cues to estimate the movement of the body. We analytically demonstrate that, as long as visual stimulation is fast in comparison to the uncertainty in our perception of body movement, the optimal strategy is to weight visually perceived movement velocities proportional to a power law. We find that this model accounts for the nonlinear influence of experimentally induced visual motion on human postural behavior both in our data and in previously published results.

  13. Emotion expression in body action and posture.

    Science.gov (United States)

    Dael, Nele; Mortillaro, Marcello; Scherer, Klaus R

    2012-10-01

    Emotion communication research strongly focuses on the face and voice as expressive modalities, leaving the rest of the body relatively understudied. Contrary to the early assumption that body movement only indicates emotional intensity, recent studies have shown that body movement and posture also conveys emotion specific information. However, a deeper understanding of the underlying mechanisms is hampered by a lack of production studies informed by a theoretical framework. In this research we adopted the Body Action and Posture (BAP) coding system to examine the types and patterns of body movement that are employed by 10 professional actors to portray a set of 12 emotions. We investigated to what extent these expression patterns support explicit or implicit predictions from basic emotion theory, bidimensional theory, and componential appraisal theory. The overall results showed partial support for the different theoretical approaches. They revealed that several patterns of body movement systematically occur in portrayals of specific emotions, allowing emotion differentiation. Although a few emotions were prototypically expressed by one particular pattern, most emotions were variably expressed by multiple patterns, many of which can be explained as reflecting functional components of emotion such as modes of appraisal and action readiness. It is concluded that further work in this largely underdeveloped area should be guided by an appropriate theoretical framework to allow a more systematic design of experiments and clear hypothesis testing.

  14. 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.

  15. [Maternal posture and its influence on birthweight].

    Science.gov (United States)

    Takito, Monica Yuri; Benício, Maria Helena D'Aquino; Latorre, Maria do Rosário Dias de Oliveira

    2005-06-01

    To analyze the relationship between maternal posture/physical activity and inadequate birthweight. Prospective cohort study involving 152 pregnant women from a public low-risk antenatal care facility. Three interviews evaluating the frequency of physical activity were administered to each pregnant woman during gestation. Birthweight (inadequate when or =3,000 g) was the dependent variable and the frequency of physical activity the independent variable. Statistical analysis was performed using logistic univariate analysis and multiple regression controlling for schooling, smoking, living with spouse, and baseline nutritional status. The practice of walking for at least 50 minutes during the first period of pregnancy was identified as a protective factor against inadequate birthweight (adjusted OR=0.44; 95% CI: 0.20-0.98). Standing for 2.5 hours or longer during the second semester of pregnancy was associated with increased risk (adjusted OR=3.23; 95% CI: 1.30-7.99). Dose-response relationships were identified for washing clothing by hand and cooking (p-value for linear trend clothing during the second trimester of gestation remained statistically significant. Our results show the importance of medical orientation regarding posture and physical activity during antenatal care, aiming at the reduction of inadequate birthweight.

  16. Earth's core formation due to the Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Ida, S.; Nakagawa, Y.; Nakazawa, K.

    1987-01-01

    A protoearth accretion stage configuration consisting of an undifferentiated solid core, an intermediate metal-melt layer, and an outer silicate-melt layer, is presently taken as the initial state in an investigation of Rayleigh-Taylor instability-induced core formation. The Ida et al. (to be published) quantitative results on the instability in a self-gravitating fluid sphere are used. The instability is found to occur through the translational mode on a time-scale of about 10 hr, in the case where the metal-melt layer is greater than about 1 km; this implies that the earth's core formed due to the undifferentiated solid core's translation upon the outer layer's melting. Differentiation would then have occurred in the late accretion stage. 17 references

  17. The SOL width and the MHD interchange instability in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Kerner, W [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Pogutse, O [Kurchatov institute, Moscow (Russian Federation)

    1994-07-01

    Instabilities in the SOL plasma can strongly influence the SOL plasma behaviour and in particular the SOL width. The SOL stability analysis shows that there exists a critical ratio of the thermal energy and the magnetic energy. If the SOL beta is greater than this critical value, the magnetic field cannot prevent the plasma displacement and a strong MHD instability in the SOL occurs. In the opposite case only slower resistive