Plantar flexor stretch reflex responses to whole body loading/unloading during human walking

DEFF Research Database (Denmark)

Grey, Michael James; van Doornik, Johannes; Sinkjær, Thomas

2002-01-01

Numerous animal and human studies have shown that afferent information from the periphery contributes to the control of walking. In particular, recent studies have consistently shown that load receptor input is an important element of the locomotion control mechanism. The objective of this study...... perturbation during human walking. Three body load conditions were investigated: normal body load, a 30% increase in body load, and a 30% decrease in body load. Healthy subjects walked on a treadmill at approximately 3.6 km/h with the left ankle attached to a portable stretching device. Dorsiflexion...... strongly to the corrective response of the stretch reflex in the plantar flexor muscles during walking....

The capsaicin cough reflex in patients with symptoms elicited by odorous chemicals

DEFF Research Database (Denmark)

Holst, H.; Arendt-Nielsen, Lars; Mosbech, H.

2010-01-01

between groups in age, body mass index or pulmonary function. The median C5 were 129 micromol/L (control group), 48 micromol/L (multiple chemical sensitivity patients), 32 micromol/L (eczema patients). The reporting of lower airway symptoms from odorous chemicals was significantly (p......Patients with multiple chemical sensitivity and eczema patients with airway symptoms elicited by odorous chemicals have enhanced cough reflex to capsaicin when applying the tidal breathing method. The aims of the present study were to test whether the capsaicin induced cough reflex was enhanced...... when applying the single breath inhalation method in similar groups of patients with symptoms related to odorous chemicals e.g. other persons wearing of perfume; and to investigate to what extent the reporting of lower airway symptoms influenced the cough reflex. Sixteen patients fulfilling Cullen...

Stretching of Active Muscle Elicits Chronic Changes in Multiple Strain Risk Factors.

Science.gov (United States)

Kay, Anthony David; Richmond, Dominic; Talbot, Chris; Mina, Minas; Baross, Anthony William; Blazevich, Anthony John

2016-07-01

The muscle stretch intensity imposed during "flexibility" training influences the magnitude of joint range of motion (ROM) adaptation. Thus, stretching while the muscle is voluntarily activated was hypothesized to provide a greater stimulus than passive stretching. The effect of a 6-wk program of stretch imposed on an isometrically contracting muscle (i.e., qualitatively similar to isokinetic eccentric training) on muscle-tendon mechanics was therefore studied in 13 healthy human volunteers. Before and after the training program, dorsiflexion ROM, passive joint moment, and maximal isometric plantarflexor moment were recorded on an isokinetic dynamometer. Simultaneous real-time motion analysis and ultrasound imaging recorded gastrocnemius medialis muscle and Achilles tendon elongation. Training was performed twice weekly and consisted of five sets of 12 maximal isokinetic eccentric contractions at 10°·s. Significant increases (P tendon stiffness) was detected (-1.5%, P > 0.05), a significant increase in tendon stiffness (31.2%, P tendon stiffness simultaneous with significant increases in tendon stiffness and decreases in passive muscle stiffness indicates that tissue-specific effects were elicited.

Comparison of the effects of hamstring stretching using proprioceptive neuromuscular facilitation with prior application of cryotherapy or ultrasound therapy

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Magalhães, Francisco Elezier Xavier; Junior, Arlindo Rodrigues de Mesquita; Meneses, Harnold’s Tyson de Sousa; Moreira dos Santos, Rayele Pricila; Rodrigues, Ezaine Costa; Gouveia, Samara Sousa Vasconcelos; Gouveia, Guilherme Pertinni de Morais; Orsini, Marco; Bastos, Victor Hugo do Vale; Machado, Dionis de Castro Dutra

2015-01-01

[Purpose] Stretching using proprioceptive neuromuscular facilitation involve physiological reflex mechanisms through submaximal contraction of agonists which activate Golgi organ, promoting the relaxation reflex. The aim of this study was to evaluate the effects of proprioceptive neuromuscular facilitation alone and with prior application of cryotherapy and thermotherapy on hamstring stretching. [Subjects and Methods] The sample comprised of 32 young subjects with hamstring retraction of the right limb. The subjects were randomly allocated to four groups: the control, flexibility PNF, flexibility PNF associated with cryotherapy, flexibility PNF in association with ultrasound therapy. [Results] After 12 stretching sessions, experimental groups showed significant improvements compared to the control group. Moreover, we did not find any significant differences among the experimental groups indicating PNF stretching alone elicits similar results to PNF stretching with prior administration of cryotherapy or thermotherapy. [Conclusion] PNF without other therapy may be a more practical and less expensive choice for clinical care. PMID:26157261

Development of Device to Evoke Stretch Reflexes by Use of Electromagnetic Force for the Rehabilitation of the Hemiplegic Upper Limb after Stroke

Science.gov (United States)

Hayashi, Ryota; Ishimine, Tomoyasu; Kawahira, Kazumi; Yu, Yong; Tsujio, Showzow

In this research, we focus on the method of rehabilitation with stretch reflexes for the hemiplegic upper limb in stroke patients. We propose a new device which utilizes electromagnetic force to evoke stretch reflexes. The device can exert an assisting force safely, because the electromagnetic force is non contact force. In this paper, we develop a support system applying the proposed device for the functional recovery training of the hemiplegic upper limb. The results obtained from several clinical tests with and without our support system are compared. Then we discuss the validity of our support system.

Group II muscle afferents probably contribute to the medium latency soleus stretch reflex during walking in humans

DEFF Research Database (Denmark)

Grey, Michael James; Ladouceur, Michel; Andersen, Jacob B.

2001-01-01

1. The objective of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. 2. Fourteen healthy subjects walked on a treadmill at approximately 3.5 km h(-1) with the left ankle...... = 0.007), whereas the short latency component was unchanged (P = 0.653). 7. An ankle block with lidocaine hydrochloride was performed to suppress the cutaneous afferents of the foot and ankle. Neither the short (P = 0.453) nor medium (P = 0.310) latency reflexes were changed. 8. Our results support...

Muscle disuse caused by botulinum toxin injection leads to increased central gain of the stretch reflex in the rat

DEFF Research Database (Denmark)

Pingel, Jessica; Hultborn, Hans; Naslund-Koch, Lui

2017-01-01

Botulinum toxin (Btx) is used in children with cerebral palsy and other neurological patients to diminish spasticity and reduce the risk of development of contractures. Here, we investigated changes in the central gain of the stretch reflex circuitry in response to botulinum toxin injection...

Peripheral venous distension elicits a blood pressure raising reflex in young and middle-aged adults.

Science.gov (United States)

Matthews, Evan L; Brian, Michael S; Coyle, Dana E; Edwards, David G; Stocker, Sean D; Wenner, Megan M; Farquhar, William B

2016-06-01

Distension of peripheral veins in humans elicits a pressor and sympathoexcitatory response that is mediated through group III/IV skeletal muscle afferents. There is some evidence that autonomic reflexes mediated by these sensory fibers are blunted with increasing age, yet to date the venous distension reflex has only been studied in young adults. Therefore, we tested the hypothesis that the venous distension reflex would be attenuated in middle-aged compared with young adults. Nineteen young (14 men/5 women, 25 ± 1 yr) and 13 middle-aged (9 men/4 women, 50 ± 2 yr) healthy normotensive participants underwent venous distension via saline infusion through a retrograde intravenous catheter in an antecubital vein during limb occlusion. Beat-by-beat blood pressure, muscle sympathetic nerve activity (MSNA), and model flow-derived cardiac output (Q), and total peripheral resistance (TPR) were recorded throughout the trial. Mean arterial pressure (MAP) increased during the venous distension in both young (baseline 83 ± 2, peak 94 ± 3 mmHg; P blood pressure, MSNA, and TPR were similar between young and middle-aged adults. Additionally, no correlation was found between age and the response to venous distension (all P > 0.05). These findings suggest that peripheral venous distension elicits a pressor and sympathetic response in middle-aged adults similar to the response observed in young adults. Copyright © 2016 the American Physiological Society.

Repeated elicitation of the acoustic startle reflex leads to sensitisation in subsequent avoidance behaviour and induces fear conditioning

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Janik Vincent M

2011-04-01

Full Text Available Abstract Background Autonomous reflexes enable animals to respond quickly to potential threats, prevent injury and mediate fight or flight responses. Intense acoustic stimuli with sudden onsets elicit a startle reflex while stimuli of similar intensity but with longer rise times only cause a cardiac defence response. In laboratory settings, habituation appears to affect all of these reflexes so that the response amplitude generally decreases with repeated exposure to the stimulus. The startle reflex has become a model system for the study of the neural basis of simple learning processes and emotional processing and is often used as a diagnostic tool in medical applications. However, previous studies did not allow animals to avoid the stimulus and the evolutionary function and long-term behavioural consequences of repeated startling remain speculative. In this study we investigate the follow-up behaviour associated with the startle reflex in wild-captured animals using an experimental setup that allows individuals to exhibit avoidance behaviour. Results We present evidence that repeated elicitation of the acoustic startle reflex leads to rapid and pronounced sensitisation of sustained spatial avoidance behaviour in grey seals (Halichoerus grypus. Animals developed rapid flight responses, left the exposure pool and showed clear signs of fear conditioning. Once sensitised, seals even avoided a known food source that was close to the sound source. In contrast, animals exposed to non-startling (long rise time stimuli of the same maximum sound pressure habituated and flight responses waned or were absent from the beginning. The startle threshold of grey seals expressed in units of sensation levels was comparable to thresholds reported for other mammals (93 dB. Conclusions Our results demonstrate that the acoustic startle reflex plays a crucial role in mediating flight responses and strongly influences the motivational state of an animal beyond a short

F response and H reflex analysis of physiological unity of gravity and antigravity muscles in man.

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García, H A; Fisher, M A

1977-01-01

Observational differences between reflex (H reflex) and antidromic (F response) activation of segmental motoneurons by a peripheral electrical stimulus are described. In contrast to H reflexes, the percentage of F responses found after a series of stimuli is directly related to the pick-up field of the recording electrode consistent with this response being due to the variable activation of a small fraction of the available motoneuron pool. Despite the differing physiological mechanisms, both F responses and H reflexes can be used to demonstrate similar relative "central excitatory states" for antigravity muscles (i.e. extensors in the lower extremity and flexors in the upper extremity) and their antagonist gravity muscles. H reflexes were elicited not only in their usual location in certain antigravity muscles but also in unusual locations by length/tension changes in agonist and antagonist groups as well as by passive stretch. The data argue for the physiological unity of similarly acting gravity and antigravity muscles as well as supporting a meaningful role of group II afferents in normal segmental motoneuron pool excitability.

[H reflex in patients with spastic quadriplegia].

Science.gov (United States)

Miyama, Sahoko; Arimoto, Kiyoshi; Kimiya, Satoshi

2009-01-01

Hoffmann reflex (H reflex) is an electrically elicited spinal monosynaptic reflex. H reflex was examined in 18 patients with spastic quadriplegia who had perinatal or postnatal problems. H reflex was elicitable in 11 patients for the abductor pollicis brevis (61.1%), 10 for the abductor digiti minimi (55.6%) and 16 for the abductor hallucis (88.9%). Because the abductor pollicis brevis and the abductor digiti minimi do not exhibit H reflex in normal subjects, it was suggested that the excitability of alpha motor neurons innervating these muscles was increased. H reflex was not detected for the extensor digitorum brevis in any patients, indicating the difference in the excitability among alpha motor neurons. In some patients, H reflex did not disappear under supramaximal stimuli. We conclude that the mechanism of evolution of H reflex in patients with spastic quadriplegia is different from that in normal subjects.

Simultaneous characterizations of reflex and nonreflex dynamic and static changes in spastic hemiparesis

Science.gov (United States)

Chung, Sun G.; Ren, Yupeng; Liu, Lin; Roth, Elliot J.; Rymer, W. Zev

2013-01-01

This study characterizes tonic and phasic stretch reflex and stiffness and viscosity changes associated with spastic hemiparesis. Perturbations were applied to the ankle of 27 hemiparetic and 36 healthy subjects under relaxed or active contracting conditions. A nonlinear delay differential equation model characterized phasic and tonic stretch reflex gains, elastic stiffness, and viscous damping. Tendon reflex was characterized with reflex gain and threshold. Reflexively, tonic reflex gain was increased in spastic ankles at rest (P hemiparesis may help to evaluate and treat them more effectively. PMID:23636726

Comparison of Stretch Reflex Torques in Ankle Dorsiflexors and Plantarflexors

National Research Council Canada - National Science Library

Tung, J

2001-01-01

...) ankle muscles, Pulse, step, and a combination of random perturbation and step inputs were used to identify the reflex and intrinsic contributions to the measured torque, TA reflex torques were very...

Tissue engineering the mechanosensory circuit of the stretch reflex arc: sensory neuron innervation of intrafusal muscle fibers.

Science.gov (United States)

Rumsey, John W; Das, Mainak; Bhalkikar, Abhijeet; Stancescu, Maria; Hickman, James J

2010-11-01

The sensory circuit of the stretch reflex arc, composed of specialized intrafusal muscle fibers and type Ia proprioceptive sensory neurons, converts mechanical information regarding muscle length and stretch to electrical action potentials and relays them to the central nervous system. Utilizing a non-biological substrate, surface patterning photolithography and a serum-free medium formulation a co-culture system was developed that facilitated functional interactions between intrafusal muscle fibers and sensory neurons. The presence of annulospiral wrappings (ASWs) and flower-spray endings (FSEs), both physiologically relevant morphologies in sensory neuron-intrafusal fiber interactions, were demonstrated and quantified using immunocytochemistry. Furthermore, two proposed components of the mammalian mechanosensory transduction system, BNaC1 and PICK1, were both identified at the ASWs and FSEs. To verify functionality of the mechanoreceptor elements the system was integrated with a MEMS cantilever device, and Ca(2+) currents were imaged along the length of an axon innervating an intrafusal fiber when stretched by cantilever deflection. This system provides a platform for examining the role of this mechanosensory complex in the pathology of myotonic and muscular dystrophies, peripheral neuropathy, and spasticity inducing diseases like Parkinson's. These studies will also assist in engineering fine motor control for prosthetic devices by improving our understanding of mechanosensitive feedback. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Do changes in spinal reflex excitability elicited by transcranial magnetic stimulation differ based on the site of cerebellar stimulation?

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Matsugi, Akiyoshi

2018-05-06

The present study aimed to investigate whether spinal reflex excitability is influenced by the site of cerebellar transcranial magnetic stimulation (C-TMS). Fourteen healthy volunteers (mean age: 24.6 ± 6.6 years [11 men]) participated. Participants lay on a bed in the prone position, with both ankle joints fixed to prevent unwanted movement. Right tibial nerve stimulation was provided to elicit the H-reflex in the right soleus muscle. Conditioning transcranial magnetic stimulation (TMS) was delivered at one of the following sites 110 ms prior to tibial stimulation: right, central, or left cerebellum; midline parietal (Pz) region; or sham stimulation. A total of 10 test trials were included for each condition, in random order. The unconditioned and conditioned H-reflexes were measured during random inter-test trials, and the cerebellar spinal facilitation (CSpF) ratios for each site were calculated (the ratio of conditioned to unconditioned H-reflexes). CSpF ratios were compared among TMS sites. CSpF ratios were significantly higher at cerebellar sites than at the Pz site or during sham stimulation. However, there was no significant difference in CSpF ratio among cerebellar sites. TMS conditioning over any part of the cerebellum facilitated the excitability of the spinal motoneuron pool. Facilitation of the H-reflex due to C-TMS may involve the effects of the bilateral descending tract of the spinal cord on the spinal motoneuron pool. Alternatively, direct brainstem stimulation may have activated portions of the bilateral descending tract of the spinal cord.

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility.

Science.gov (United States)

Wong, Del P; Chaouachi, Anis; Lau, Patrick W C; Behm, David G

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key pointsThe duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001).No significant differences in RSA and COD between the 3 stretching conditions.The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects.The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility

Science.gov (United States)

Wong, Del P.; Chaouachi, Anis; Lau, Patrick W.C.; Behm, David G.

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key points The duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). No significant differences in RSA and COD between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. PMID:24149890

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) with chronic cough and preserved muscle stretch reflexes: evidence for selective sparing of afferent Ia fibres.

Science.gov (United States)

Infante, Jon; García, Antonio; Serrano-Cárdenas, Karla M; González-Aguado, Rocío; Gazulla, José; de Lucas, Enrique M; Berciano, José

2018-04-25

The aim of this study was to describe five patients with cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) with chronic cough and preserved limb muscle stretch reflexes. All five patients were in the seventh decade of age, their gait imbalance having been initiated in the fifth decade. In four patients cough antedated gait imbalance between 15 and 29 years; cough was spasmodic and triggered by variable factors. Established clinical picture included severe hypopallesthesia predominating in the lower limbs with postural imbalance, and variable degree of cerebellar axial and appendicular ataxia, dysarthria and horizontal gaze-evoked nystagmus. Upper- and lower-limb tendon jerks were preserved, whereas jaw jerk was absent. Vestibular function testing showed bilateral impairment of the vestibulo-ocular reflex. Nerve conduction studies demonstrated normal motor conduction parameters and absence or severe attenuation of sensory nerve action potentials. Somatosensory evoked potentials were absent or severely attenuated. Biceps and femoral T-reflex recordings were normal, while masseter reflex was absent or attenuated. Sympathetic skin responses were normal. Cranial MRI showed vermian and hemispheric cerebellar atrophy predominating in lobules VI, VII and VIIa. We conclude that spasmodic cough may be an integral part of the clinical picture in CANVAS, antedating the appearance of imbalance in several decades and that sparing of muscle spindle afferents (Ia fibres) is probably the pathophysiological basis of normoreflexia.

The Dynamics of Prosthetically Elicited Vestibulo-Ocular Reflex Function Across Frequency and Context in the Rhesus Monkey

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James O. Phillips

2018-05-01

Full Text Available Electrical vestibular neurostimulation may be a viable tool for modulating vestibular afferent input to restore vestibular function following injury or disease. To do this, such stimulators must provide afferent input that can be readily interpreted by the central nervous system to accurately represent head motion to drive reflexive behavior. Since vestibular afferents have different galvanic sensitivity, and different natural sensitivities to head rotational velocity and acceleration, and electrical stimulation produces aphysiological synchronous activation of multiple afferents, it is difficult to assign a priori an appropriate transformation between head velocity and acceleration and the properties of the electrical stimulus used to drive vestibular reflex function, i.e., biphasic pulse rate or pulse current amplitude. In order to empirically explore the nature of the transformation between vestibular prosthetic stimulation and vestibular reflex behavior, in Rhesus macaque monkeys we parametrically varied the pulse rate and current amplitude of constant rate and current amplitude pulse trains, and the modulation frequency of sinusoidally modulated pulse trains that were pulse frequency modulated (FM or current amplitude modulated (AM. In addition, we examined the effects of differential eye position and head position on the observed eye movement responses. We conclude that there is a strong and idiosyncratic, from canal to canal, effect of modulation frequency on the observed eye velocities that are elicited by stimulation. In addition, there is a strong effect of initial eye position and initial head position on the observed responses. These are superimposed on the relationships between pulse frequency or current amplitude and eye velocity that have been shown previously.

The Relation Between Stretching Typology and Stretching Duration: The Effects on Range of Motion.

Science.gov (United States)

Thomas, Ewan; Bianco, Antonino; Paoli, Antonio; Palma, Antonio

2018-04-01

Different stretching strategies and protocols are widely used to improve flexibility or maintain health, acting on the muscle tendon-unit, in order to improve the range of motion (ROM) of the joints. This review aims to evaluate the current body of literature in order to understand the relation between stretching typology and ROM, and secondly to evaluate if a relation exists between stretching volume (either as a single training session, weekly training and weekly frequency) and ROM, after long-term stretching. Twenty-three articles were considered eligible and included in the quantitative synthesis. All stretching typologies showed ROM improvements over a long-term period, however the static protocols showed significant gains (p<0.05) when compared to the ballistic or PNF protocols. Time spent stretching per week seems fundamental to elicit range of movement improvements when stretches are applied for at least or more than 5 min, whereas the time spent stretching within a single session does not seem to have significant effects for ROM gains. Weekly frequency is positively associated to ROM. Evaluated data indicates that performing stretching at least 5 days a week for at least 5 min per week using static stretching may be beneficial to promote ROM improvements. © Georg Thieme Verlag KG Stuttgart · New York.

Arakeri’s Reflex: an Alternative Pathway for Dento-Cardiac Reflex Mediated Syncope

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Veena Arali

2010-03-01

Full Text Available Introduction: Dentocardiac reflex, a variant of trigeminocardiac reflex elicited specifically during tooth extraction procedures in den-tal/maxillofacial surgery and is believed to cause syncope with an afferent link mediated by posterior superior alveolar nerve. Another variant of trigeminocardiac reflex which is also of interest to the oral and maxillofacial surgeon is oculocardiac reflex which can be triggered by direct or indirect manipulation of eye globe or muscles around it.The hypothesis: Excessive or injudicious pressure or manipulations around the maxillary first molars during extraction procedure are as-sociated with maximum incidence of bradycardia and hypotension than around incisor/ canine/ third molars. This is because; the pressure on eye globe and ophthalmic rectus muscle is maximum during extraction of first molar than incisor/canine and third molars. This observation led us to postulate an alternative pathway for dentocardiac reflex mediated syncope which may possibly justify the maxillary first molar region as a prone factor for the trigger. Evaluation of the hypothesis: Present hypothesis may not confer the specific factor responsible for switch in autonomic response in syncope origin during the tooth extraction procedure, but may provide a clue to where we should be looking.

Neurophysiologic effects of spinal manipulation in patients with chronic low back pain

Directory of Open Access Journals (Sweden)

Walkowski Stevan

2011-07-01

Full Text Available Abstract Background While there is growing evidence for the efficacy of SM to treat LBP, little is known on the mechanisms and physiologic effects of these treatments. Accordingly, the purpose of this study was to determine whether SM alters the amplitude of the motor evoked potential (MEP or the short-latency stretch reflex of the erector spinae muscles, and whether these physiologic responses depend on whether SM causes an audible joint sound. Methods We used transcranial magnetic stimulation to elicit MEPs and electromechanical tapping to elicit short-latency stretch reflexes in 10 patients with chronic LBP and 10 asymptomatic controls. Neurophysiologic outcomes were measured before and after SM. Changes in MEP and stretch reflex amplitude were examined based on patient grouping (LBP vs. controls, and whether SM caused an audible joint sound. Results SM did not alter the erector spinae MEP amplitude in patients with LBP (0.80 ± 0.33 vs. 0.80 ± 0.30 μV or in asymptomatic controls (0.56 ± 0.09 vs. 0.57 ± 0.06 μV. Similarly, SM did not alter the erector spinae stretch reflex amplitude in patients with LBP (0.66 ± 0.12 vs. 0.66 ± 0.15 μV or in asymptomatic controls (0.60 ± 0.09 vs. 0.55 ± 0.08 μV. Interestingly, study participants exhibiting an audible response exhibited a 20% decrease in the stretch reflex (p Conclusions These findings suggest that a single SM treatment does not systematically alter corticospinal or stretch reflex excitability of the erector spinae muscles (when assessed ~ 10-minutes following SM; however, they do indicate that the stretch reflex is attenuated when SM causes an audible response. This finding provides insight into the mechanisms of SM, and suggests that SM that produces an audible response may mechanistically act to decrease the sensitivity of the muscle spindles and/or the various segmental sites of the Ia reflex pathway.

Reflexes in the shoulder muscles elicited from the human coracoacromial ligament.

Science.gov (United States)

Diederichsen, Louise Pyndt; Nørregaard, Jesper; Krogsgaard, Michael; Fischer-Rasmussen, Torsten; Dyhre-Poulsen, Poul

2004-09-01

Morphological studies have demonstrated mechanoreceptors in the capsuloligamentous structures of the shoulder joint, however knowledge of the role these joint receptors play in the control of shoulder stability is limited. We therefore investigated the effect of electrically induced afferent activity from mechanoreceptors in the coracoacromial ligament (CAL) on the activity of voluntary activated shoulder muscles in healthy humans. In study I, wire electrodes, for electrical stimulation, were inserted into the CAL in eight normal shoulders. In study II, a needle electrode was inserted into the CAL in seven normal shoulders. Electric activity was recorded from eight shoulder muscles by surface and intramuscular electrodes. During isometric contractions, electrical stimulation was applied to the CAL at two different stimulus intensities, a weak stimulus (stim-1) and a stronger stimulus (stim-2). In both experiments, electrical stimulation of the CAL elicited a general inhibition in the voluntary activated shoulder muscles. In study I the average latencies (mean+/-SE) of the muscular inhibition were 66+/-4 ms (stim-1) and 62+/-4 ms (stim-2) during isometric flexion and 73+/-3 ms (stim-1) and 73+/-5 ms (stim-2) during isometric extension. In study II the average latency (mean+/-SE) of the response was 66+/-4 ms (stim-1) during isometric flexion. Our results demonstrated a response, probably of reflex origin, from mechanoreceptors in the CAL to the shoulder muscles. The existence of this synaptic connection between mechanoreceptors in CAL and the shoulder muscles suggest a role of these receptors in muscle coordination and in the functional joint stability.

SHORT DURATIONS OF STATIC STRETCHING WHEN COMBINED WITH DYNAMIC STRETCHING DO NOT IMPAIR REPEATED SPRINTS AND AGILITY

Directory of Open Access Journals (Sweden)

Del P. Wong

2011-06-01

Full Text Available This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA and change of direction (COD. Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s. Three dynamic stretching exercises of 30 s duration were then performed (90 s total. Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p < 0.001. However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (< 90 s static stretching may not have provided sufficient stimulus to elicit performance impairments

Effects of intravenous nonsteroidal antiinflammatory drugs on a C-fiber reflex elicited by a wide range of stimulus intensities in the rat.

Science.gov (United States)

Bustamante, D; Paeile, C; Willer, J C; Le Bars, D

1996-03-01

A C-fiber reflex elicited by electrical stimulation within the territory of the sural nerve, was recorded from the ipsilateral biceps femoris muscle in anesthetized rats. The temporal evolution of the response was studied using a constant stimulus intensity (3 x threshold) and recruitment curves were built by varying stimulus intensity from 0 to 7 x threshold. The i.v. administration of aspirin, indomethacin, ketoprofen, paracetamol (= acetaminophen) and lysine clonixinate resulted in dose-dependent depressions of the C-fiber reflex by up to 30 to 40%. By contrast, saline was ineffective. High doses of the effective drugs that produced large disturbances in heart rate and/or acid-base equilibrium were not considered in the pharmacological analysis. When a constant level of stimulation was used, different dose-dependent profiles of drug action were observed. Aspirin induced a slow and gradual depression, although indomethacin, ketoprofen and paracetamol produced a peak effect within the first 10-min period and then reached a steady state phase for up to 30 min. The depressive effects of lysine clonixinate appeared more stable. When recruitment curves were built with a range of nociceptive stimulus intensities, all the drugs produced a dose-dependent decrease in the slopes and the areas under the recruitment curves without any major modification in the thresholds. The order of potency was the same for both stimulation paradigms, e.g., aspirin lysine clonixinate = ketoprofen < indomethacin. It is concluded that NSAID elicit significant antinociceptive effects at a central level, which do not depend on the existence of a hyperalgesic or inflammatory state.

Changes in soleus H-reflex during walking in middle-aged, healthy subjects

DEFF Research Database (Denmark)

Raffalt, Peter C; Alkjær, Tine; Simonsen, Erik B

2015-01-01

INTRODUCTION: To assess the effect of aging on stretch reflex modulation during walking, soleus H-reflexes obtained in 15 middle-aged (mean age 56.4±6.9 years) and 15 young (mean age 23.7±3.9 years) subjects were compared. METHODS: The H-reflex amplitude, muscle activity (EMG) of the soleus...... and tibialis anterior muscles, and EMG/H-reflex gain were measured during 4-km/h treadmill walking. RESULTS: The normalized H-reflex amplitude was lower in the swing phase for the middle-aged group, and there was no difference in muscle activity. EMG/H-reflex gain did not differ between groups. CONCLUSIONS: H......-reflex amplitude during walking was affected by aging, and changes during the swing phase could be seen in the middle-aged subjects. Subdividing the 2 age groups into groups of facilitated or suppressed swing-phase H-reflex revealed that the H-reflex amplitude modulation pattern in the group with facilitated swing...

Low Incidence Of Extensor Plantar Reflex In Newborns In An ...

African Journals Online (AJOL)

Healthy term newborns with Apgar score of 8 and above at one minute were recruited into the study consecutively in a maternity hospital in Ibadan, Nigeria. The plantar reflex was elicited by stroking the lateral side of the sole with firm pressure, between 24 - 48 hours after delivery. Results Of 461 newborns, the plantar reflex ...

Alleviation of Motor Impairments in Patients with Cerebral Palsy: Acute Effects of Whole-body Vibration on Stretch Reflex Response, Voluntary Muscle Activation and Mobility

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Anne Krause

2017-08-01

Full Text Available IntroductionIndividuals suffering from cerebral palsy (CP often have involuntary, reflex-evoked muscle activity resulting in spastic hyperreflexia. Whole-body vibration (WBV has been demonstrated to reduce reflex activity in healthy subjects, but evidence in CP patients is still limited. Therefore, this study aimed to establish the acute neuromuscular and kinematic effects of WBV in subjects with spastic CP.Methods44 children with spastic CP were tested on neuromuscular activation and kinematics before and immediately after a 1-min bout of WBV (16–25 Hz, 1.5–3 mm. Assessment included (1 recordings of stretch reflex (SR activity of the triceps surae, (2 electromyography (EMG measurements of maximal voluntary muscle activation of lower limb muscles, and (3 neuromuscular activation during active range of motion (aROM. We recorded EMG of m. soleus (SOL, m. gastrocnemius medialis (GM, m. tibialis anterior, m. vastus medialis, m. rectus femoris, and m. biceps femoris. Angular excursion was recorded by goniometry of the ankle and knee joint.ResultsAfter WBV, (1 SOL SRs were decreased (p < 0.01 while (2 maximal voluntary activation (p < 0.05 and (3 angular excursion in the knee joint (p < 0.01 were significantly increased. No changes could be observed for GM SR amplitudes or ankle joint excursion. Neuromuscular coordination expressed by greater agonist–antagonist ratios during aROM was significantly enhanced (p < 0.05.DiscussionThe findings point toward acute neuromuscular and kinematic effects following one bout of WBV. Protocols demonstrate that pathological reflex responses are reduced (spinal level, while the execution of voluntary movement (supraspinal level is improved in regards to kinematic and neuromuscular control. This facilitation of muscle and joint control is probably due to a reduction of spasticity-associated spinal excitability in favor of giving access for greater supraspinal input during voluntary motor

Inhibition of reflex vagal bradycardia by a central action of 5-hydroxytryptophan.

OpenAIRE

Tadepalli, A. S.

1980-01-01

1 Vagally mediated reflex bradycardia was elicited in spinal cats with intravenous pressor doses of noradrenaline. Administration of 5-hydroxytryptophan (1.5 and 3 mg total dose) into the fourth cerebral ventricle reduced the reflex bradycardia. 2 Inhibition of central amino acid decarboxylase with R044602 prevented the effects of 5-hydroxytryptophan. After intravenous administration of 5-hydroxytryptophan, vagal reflex bradycardia was not affected. 3 Results suggest that 5-hydroxytryptophan ...

Role of the brain stem in tibial inhibition of the micturition reflex in cats.

Science.gov (United States)

Ferroni, Matthew C; Slater, Rick C; Shen, Bing; Xiao, Zhiying; Wang, Jicheng; Lee, Andy; Roppolo, James R; de Groat, William C; Tai, Changfeng

2015-08-01

This study examined the role of the brain stem in inhibition of bladder reflexes induced by tibial nerve stimulation (TNS) in α-chloralose-anesthetized decerebrate cats. Repeated cystometrograms (CMGs) were performed by infusing saline or 0.25% acetic acid (AA) to elicit normal or overactive bladder reflexes, respectively. TNS (5 or 30 Hz) at three times the threshold (3T) intensity for inducing toe movement was applied for 30 min between CMGs to induce post-TNS inhibition or applied during the CMGs to induce acute TNS inhibition. Inhibition was evident as an increase in bladder capacity without a change in amplitude of bladder contractions. TNS applied for 30 min between saline CMGs elicited prolonged (>2 h) poststimulation inhibition that significantly (P reflexes but are not involved in inhibition of normal bladder reflexes. Copyright © 2015 the American Physiological Society.

Sympathetic reflex control of blood flow in human peripheral tissues

DEFF Research Database (Denmark)

Henriksen, O

1991-01-01

Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human...... sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno...... skeletal muscle, cutaneous and subcutaneous tissues of the limbs indicate that the situation is more complex. Measurements have been carried out during acute as well as chronic sympathetic denervation. Spinal sympathetic reflex mechanisms have been evaluated in tetraplegic patients, where supraspinal...

The Cerebellum in Maintenance of a Motor Skill: A Hierarchy of Brain and Spinal Cord Plasticity Underlies H-Reflex Conditioning

Science.gov (United States)

Wolpaw, Jonathan R.; Chen, Xiang Yang

2006-01-01

Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, is a simple model of skill acquisition and involves plasticity in the spinal cord. Previous work showed that the cerebellum is essential for down-conditioning the H-reflex. This study asks whether the cerebellum is also essential for maintaining…

Interindividual differences in H reflex modulation during normal walking

DEFF Research Database (Denmark)

Simonsen, Erik B; Dyhre-Poulsen, Poul; Alkjaer, T

2002-01-01

was greater for the S group. The hip joint moment was similar for the groups. The EMG activity in the vastus lateralis and anterior tibial muscles was greater prior to heel strike for the S group. These data indicate that human walking exhibits at least two different motor patterns as evaluated by gating...... of afferent input to the spinal cord, by EMG activity and by walking mechanics. Increasing H reflex excitability during the swing phase appears to protect the subject against unexpected perturbations around heel strike by a facilitated stretch reflex in the triceps surae muscle. Alternatively, in subjects...... with a suppressed H reflex in the swing phase the knee joint extensors seem to form the primary protection around heel strike....

Oculocardiac reflex elicited by orbital floor fracture and inferior globe displacement

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Chau M. Pham

2017-06-01

Conclusions and importance: The oculocardiac reflex can precipitate marked bradycardia and hypotension in the setting of trauma with significant orbital and maxillofacial injury. Prompt identification and management with vagolytic agents or definitive surgical intervention may prevent morbidity or mortality.

Test-retest reliability of the soleus H-reflex excitability measured during human walking

DEFF Research Database (Denmark)

Simonsen, Erik B; Dyhre-Poulsen, Poul

2010-01-01

The purpose of the study was to investigate with what accuracy the soleus H-reflex modulation and excitability could be measured during human walking on two occasions separated by days. The maximal M-wave (Mmax) was measured at rest in the standing position. During treadmill walking every stimulus...... elicited an M-wave of 25+/-10% of Mmax in the soleus muscle and a supra-maximal stimulus elicited a maximal M-wave 60ms after the first stimulus. Both Mmax during rest and during walking were later used for normalization. When normalized to resting Mmax, the peak reflex amplitude during walking was 5...

Cortical and spinal assessment - a comparative study using encephalography and the nociceptive withdrawal reflex

DEFF Research Database (Denmark)

Fischer, I W; Gram, M; Hansen, T M

2017-01-01

solution in randomized order. The electroencephalogram (EEG) was recorded during rest and during immersion of the hand into ice-water. Electrical stimulation of the sole of the foot was used to elicit the nociceptive withdrawal reflex and the reflex amplitude was recorded. RESULTS: Data from thirty...

Vergence increases the gain of the human angular vestibulo-ocular reflex during peripheral hyposensitivity elicited by cold thermal irrigation.

Science.gov (United States)

Tamás, László T; Lundberg, Yunxia W; Büki, Béla

2018-01-01

When viewing a far target, the gain of the horizontal vestibulo-ocular reflex (VOR) is around 1.0, but when viewing a near target there is an increased response. It has been shown that while this convergence-mediated modulation is unaffected by canal plugging and clinically practical transmastoid galvanic stimulation, it is eliminated by a partial peripheral gentamicin lesion. The aim of this study was to determine if convergence increases the gain during peripheral hyposensitivity elicited by cold thermal irrigation. The high frequency VOR gain was measured using video head impulse testing immediately after the cold caloric stimulus in 9 healthy human subjects with the lateral semicircular canals oriented approximately earth-vertical. Before caloric irrigation, near viewing (15 cm) increased the average VOR gain by 28% (from 1 to 1.28). Cold (24°C) water irrigation of the right ear decreased the gain to 0.66 (far viewing) and 0.82 (near viewing) (22% difference). Although vergence also increased the gain for impulses to the left to the same degree before caloric stimulus, the caloric irrigation itself (applied to the right ear) did not influence the gain for contralateral impulses. In our experiments vergence increased the gain of the human angular VOR during peripheral hyposensitivity elicited by cold thermal irrigation. These results suggest that cold irrigation does not abolish the function of the nonlinear/phasic vestibular afferent pathway.

Short-term locomotor adaptation to a robotic ankle exoskeleton does not alter soleus Hoffmann reflex amplitude.

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Kao, Pei-Chun; Lewis, Cara L; Ferris, Daniel P

2010-07-26

To improve design of robotic lower limb exoskeletons for gait rehabilitation, it is critical to identify neural mechanisms that govern locomotor adaptation to robotic assistance. Previously, we demonstrated soleus muscle recruitment decreased by approximately 35% when walking with a pneumatically-powered ankle exoskeleton providing plantar flexor torque under soleus proportional myoelectric control. Since a substantial portion of soleus activation during walking results from the stretch reflex, increased reflex inhibition is one potential mechanism for reducing soleus recruitment when walking with exoskeleton assistance. This is clinically relevant because many neurologically impaired populations have hyperactive stretch reflexes and training to reduce the reflexes could lead to substantial improvements in their motor ability. The purpose of this study was to quantify soleus Hoffmann (H-) reflex responses during powered versus unpowered walking. We tested soleus H-reflex responses in neurologically intact subjects (n=8) that had trained walking with the soleus controlled robotic ankle exoskeleton. Soleus H-reflex was tested at the mid and late stance while subjects walked with the exoskeleton on the treadmill at 1.25 m/s, first without power (first unpowered), then with power (powered), and finally without power again (second unpowered). We also collected joint kinematics and electromyography. When the robotic plantar flexor torque was provided, subjects walked with lower soleus electromyographic (EMG) activation (27-48%) and had concomitant reductions in H-reflex amplitude (12-24%) compared to the first unpowered condition. The H-reflex amplitude in proportion to the background soleus EMG during powered walking was not significantly different from the two unpowered conditions. These findings suggest that the nervous system does not inhibit the soleus H-reflex in response to short-term adaption to exoskeleton assistance. Future studies should determine if the

Muscle and reflex changes with varying joint angle in hemiparetic stroke

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Alibiglou Laila

2008-02-01

Full Text Available Abstract Background Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint. Methods Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM. Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls. Results Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position. Conclusion In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated. Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects

Limitations of learning in the proboscis reflex of the flower visiting syrphid fly Eristalis tenax

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An, Lina; Donda, Miriam; Hohmann, Michele; Sermon, Leonie; Stegmanns, Vanessa

2018-01-01

Flower visiting Eristalis hoverflies feed on nectar and pollen and are known to rely on innate colour preferences. In addition to a preference for visiting yellow flowers, the flies possess an innate proboscis reflex elicited by chemical as well as yellow colour stimuli. In this study we show that the flies’ proboscis reflex is only triggered by yellow colour stimuli and not altered by conditioning to other colours. Neither in absolute nor in differential conditioning experiments the flies learned to associate other colours than yellow with reward. Even flies that experienced only blue nutrients during the first four days after hatching could not be trained to extend the proboscis towards other colours than yellow. The natural targets of the visually elicited proboscis reflex are yellow pollen and yellow anthers. One consequence of our findings is that flowers might advertise nectar and pollen rewards for Eristalis hoverflies by a yellow colour hue of nectar guides, nectaries, stamens or pollen. Alternatively, flowers might protect their pollen against Eristalis by displaying other pollen colours than yellow or direct flies by yellow pollen-mimicking floral guides towards nectar resources. Testing the proboscis extension of various hoverfly species in the field showed that only Eristalis hoverflies possess the proboscis reflex elicited by yellow colour hues. PMID:29558491

Cardiac effects of electrically induced intrathoracic autonomic reflexes.

Science.gov (United States)

Armour, J A

1988-06-01

Electrical stimulation of the afferent components in one cardiopulmonary nerve (the left vagosympathetic complex at a level immediately caudal to the origin of the left recurrent laryngeal nerve) in acutely decentralized thoracic autonomic ganglionic preparations altered cardiac chronotropism and inotropism in 17 of 44 dogs. Since these neural preparations were acutely decentralized, the effects were mediated presumably via intrathoracic autonomic reflexes. The lack of consistency of these reflexly generated cardiac responses presumably were due in part to anatomical variation of afferent axons in the afferent nerve stimulated. As stimulation of the afferent components in the same neural structure caudal to the heart (where cardiopulmonary afferent axons are not present) failed to elicit cardiac responses in any dog, it is presumed that when cardiac responses were elicited by the more cranially located stimulations, these were due to activation of afferent axons arising from the heart and (or) lungs. When cardiac responses were elicited, intramyocardial pressures in the right ventricular conus as well as the ventral and lateral walls of the left ventricle were augmented. Either bradycardia or tachycardia was elicited. Following hexamethonium administration no responses were produced, demonstrating that nicotonic cholinergic synaptic mechanisms were involved in these intrathoracic cardiopulmonary-cardiac reflexes. In six of the animals, when atropine was administered before hexamethonium, reflexly generated responses were attenuated. The same thing occurred when morphine was administered in four animals. In contrast, in four animals following administration of phentolamine, the reflexly generated changes were enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of stretch reflex responses evoked during drop jumping in highly skilled atheles versus untrained subjects.

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Judge, L W; Burke, J R

2015-06-01

The purpose of the study was to describe changes in the excitability of the stretch reflex response (SRR) during different drop jumps as a function of training background and as an adaptation to a preseason sport-specific resistance training program. Twelve collegiate field event athletes (discus, hammer, javelin, shot put, and weight; 9 males and 3 females) and 12 college-aged control subjects performed the following three jumps: (1) countermovement jump (CMJ); (2) countermovement drop jump; and (3) bounce-drop jump (BDJ). Neuromechanical changes in the performance of drop jumps by athletes were measured during the sport-specific resistance training program. Pre-post testing of drop jump performance by control subjects was included for comparison. For each jump trial, ground reaction forces (GRF), electromyograms (EMG) and cinematographic data were collected. There were no training adaptations. However, jump heights were greater for the athletes than the controls among the different jumps with the jump heights for all subjects being less during the BDJ than CMJ and CDJ. In athletes only, there was a differential modulation of the SRR from the gastrocnemius muscle with different levels of background muscle activity for the CDJ and BDJ. There were changes in excitability of SRR from the gastrocnemius muscle as a function of training background. Interrelated neuromechanical mechanisms to include landing biomechanics, intrinsic musculotendinous tissue properties of the ankle, and centrally regulated motor commands may underlie the facilitation of the SRR from the gastrocnemius muscle in athletes as compared to controls.

Blockade of acid sensing ion channels attenuates the exercise pressor reflex in cats.

Science.gov (United States)

Hayes, Shawn G; Kindig, Angela E; Kaufman, Marc P

2007-06-15

Although thin fibre muscle afferents possess acid sensing ion channels (ASICs), their contribution to the exercise pressor reflex is not known. This lack of information is partly attributable to the fact that there is no known selective in vivo antagonist for ASICs. Although amiloride has been shown to antagonize ASICs, it also has been shown to antagonize voltage-gated sodium channels, thereby impairing impulse conduction in sensory nerves. Our aim was to test the hypothesis that lactic acid accumulation in exercising muscle acted on ASICs located on thin fibre muscle afferents to evoke the metabolic component of the exercise pressor reflex. To test this hypothesis, we determined in decerebrate cats if amiloride attenuated the pressor and cardioaccelerator responses to static contraction, to tendon stretch and to arterial injections of lactic acid and capsaicin. We found a dose of amiloride (0.5 microg kg(-1); i.a.) that attenuated the pressor and cardioaccelerator responses to both contraction and lactic acid injection, but had no effect on the responses to stretch and capsaicin. A higher dose of amiloride (5 microg kg(-1), i.a.) not only blocked the pressor and cardioaccelerator responses to lactic acid and contraction, but also attenuated the responses to stretch and to capsaicin, manoeuvers in which ASICs probably play no significant role. In addition, we found that the low dose of amiloride (0.5 microg kg(-1)) had no effect on the responses of muscle spindles to tendon stretch and to succinylcholine, whereas the high dose (5 microg kg(-1)) attenuated the responses to both. Our data suggest the low dose of amiloride used in our experiments selectively blocked ASICs, whereas the high dose blocked ASICs and impulse conduction in muscle afferents. We conclude that ASICs play a role in the metabolic component of the exercise pressor reflex.

Operant conditioning of the soleus H-reflex does not induce long-term changes in the gastrocnemius H-reflexes and does not disturb normal locomotion in humans.

Science.gov (United States)

Makihara, Yukiko; Segal, Richard L; Wolpaw, Jonathan R; Thompson, Aiko K

2014-09-15

In normal animals, operant conditioning of the spinal stretch reflex or the H-reflex has lesser effects on synergist muscle reflexes. In rats and people with incomplete spinal cord injury (SCI), soleus H-reflex operant conditioning can improve locomotion. We studied in normal humans the impact of soleus H-reflex down-conditioning on medial (MG) and lateral gastrocnemius (LG) H-reflexes and on locomotion. Subjects completed 6 baseline and 30 conditioning sessions. During conditioning trials, the subject was encouraged to decrease soleus H-reflex size with the aid of visual feedback. Every sixth session, MG and LG H-reflexes were measured. Locomotion was assessed before and after conditioning. In successfully conditioned subjects, the soleus H-reflex decreased 27.2%. This was the sum of within-session (task dependent) adaptation (13.2%) and across-session (long term) change (14%). The MG H-reflex decreased 14.5%, due mainly to task-dependent adaptation (13.4%). The LG H-reflex showed no task-dependent adaptation or long-term change. No consistent changes were detected across subjects in locomotor H-reflexes, EMG activity, joint angles, or step symmetry. Thus, in normal humans, soleus H-reflex down-conditioning does not induce long-term changes in MG/LG H-reflexes and does not change locomotion. In these subjects, task-dependent adaptation of the soleus H-reflex is greater than it is in people with SCI, whereas long-term change is less. This difference from results in people with SCI is consistent with the fact that long-term change is beneficial in people with SCI, since it improves locomotion. In contrast, in normal subjects, long-term change is not beneficial and may necessitate compensatory plasticity to preserve satisfactory locomotion. Copyright © 2014 the American Physiological Society.

Short-term plasticity in a monosynaptic reflex pathway to forearm muscles after continuous robot-assisted passive stepping

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Tsuyoshi Nakajima

2016-07-01

Full Text Available Both active and passive rhythmic limb movements reduce the amplitude of spinal cord Hoffmann (H- reflexes in muscles of moving and distant limbs. This could have clinical utility in remote modulation of the pathologically hyperactive reflexes found in spasticity after stroke or spinal cord injury. However, such clinical translation is currently hampered by a lack of critical information regarding the minimum or effective duration of passive movement needed for modulating spinal cord excitability. We therefore investigated the H-reflex modulation in the flexor carpi radialis (FCR muscle during and after various durations (5, 10, 15, and 30 min of passive stepping in 11 neurologically normal subjects. Passive stepping was performed by a robotic gait trainer system (Lokomat® while a single pulse of electrical stimulation to the median nerve elicited H-reflexes in the FCR. The amplitude of the FCR H-reflex was significantly suppressed during passive stepping. Although 30 minutes of passive stepping was sufficient to elicit a persistent H-reflex suppression that lasted up to 15 minutes, 5 minutes of passive stepping was not. The duration of H-reflex suppression correlated with that of the stepping. These findings suggest that the accumulation of stepping-related afferent feedback from the leg plays a role in generating short-term interlimb plasticity in the circuitry of the FCR H-reflex.

Preservation of veno-arteriolar reflex in the skin following 20 days of head down bed rest in humans

DEFF Research Database (Denmark)

Gabrielsen, A; Suzuki, Y; Norsk, P

1999-01-01

an orthostatic stress after spaceflight could be another important mechanism for orthostatic intolerance. Previous investigations have revealed that a local veno-arteriolar reflex is present in cutaneous, subcutaneous and muscle tissue. The reflex response is elicited in response to an increase in transmural...

The capsaicin cough reflex in eczema patients with respiratory symptoms elicited by perfume

DEFF Research Database (Denmark)

Elberling, Jesper; Dirksen, Asger; Johansen, Jeanne Duus

2006-01-01

Respiratory symptoms elicited by perfume are common in the population but have unclear pathophysiology. Increased capsaicin cough responsiveness has been associated with the symptoms, but it is unknown whether the site of the symptoms in the airways influences this association. The aim of this st......Respiratory symptoms elicited by perfume are common in the population but have unclear pathophysiology. Increased capsaicin cough responsiveness has been associated with the symptoms, but it is unknown whether the site of the symptoms in the airways influences this association. The aim...... of this study was to investigate the association between the site of airway symptoms elicited by perfume and cough responsiveness to bronchial challenge with capsaicin. 21 eczema patients with respiratory symptoms elicited by perfume were compared with 21 healthy volunteers in a sex- and age-matched case...... control study. The participants completed a symptom questionnaire and underwent a bronchial challenge with capsaicin. Lower, but not upper, respiratory symptoms elicited by perfume were associated with increased capsaicin cough responsiveness. Having severe symptoms to perfume (n=11) did not relate...

Proximally evoked soleus H-reflex to S1 nerve root stimulation in sensory neuronopathies (ganglionopathies).

Science.gov (United States)

Zhu, Dong-Qing; Zhu, Yu; Qiao, Kai; Zheng, Chao-Jun; Bradley, Scott; Weber, Robert; Chen, Xiang-Jun

2013-11-01

Sensory neuronopathy (SNN) mimics distal sensory axonopathy. The conventional H-reflex elicited by tibial nerve stimulation (tibial H-reflex) is usually abnormal in both conditions. We evaluated the proximally evoked soleus H-reflex in response to S1 nerve root stimulation (S1 foramen H-reflex) in SNN. Eleven patients with SNN and 6 with distal sensory axonopathy were studied. Tibial and S1 foramen H-reflexes were performed bilaterally in each patient. Tibial and S1 foramen H-reflexes were absent bilaterally in all patients with SNN. In the patients with distal sensory axonopathy, tibial H-reflexes were absent in 4 and demonstrated prolonged latencies in 2, but S1 foramen H-reflexes were normal. Characteristic absence of the H-reflex after both proximal and distal stimulation reflects primary loss of dorsal root ganglion (DRG) neurons and the distinct non-length-dependent impairment of sensory nerve fibers in SNN. Copyright © 2013 Wiley Periodicals, Inc.

Reflexives and reflexive constructions in Afrikaans

African Journals Online (AJOL)

Kate H

2. Reflexives. Afrikaans items belonging to the traditional lexical category of reflexives (or reflexive ... reflexive and non-reflexive pronouns are syntactically derived from the same lexical root pronoun √PRON. The ...... 32 The matrix verbs in (33) and (34) both concern a future activity of an entity: belowe (“promise”) in the (a).

Short-term pressure induced suppression of the short-latency response: a new methodology for investigating stretch reflexes

DEFF Research Database (Denmark)

Leukel, Christian; Lundbye-Jensen, Jesper; Gruber, Markus

2009-01-01

During experiments involving ischemic nerve block, we noticed that the short-latency response (SLR) of evoked stretches in m. soleus decreased immediately following inflation of a pneumatic cuff surrounding the lower leg. The present study aimed to investigate this short-term effect of pressure......) were recorded. Additionally, stretches were applied with different velocities and amplitudes. Finally, the SLR was investigated during hopping and in two protocols that modified the ability of the muscle-tendon complex distal to the cuff to stretch. All measurements were performed with deflated...

Reversal of functional disorders by aspiration, expiration and cough reflexes and their voluntary counterparts

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Zoltan eTomori

2012-12-01

Full Text Available Agonal gasping provoked by asphyxia can save ~15% of mammals even from untreated ventricular fibrillation, but it fails to revive infants with sudden infant death syndrome. Our systematic study of airway reflexes in cats and other animals indicated that in addition to cough, there are 2 distinct airway reflexes that may contribute to auto-resuscitation. Gasp- and sniff-like spasmodic inspirations can be elicited by nasopharyngeal stimulation, strongly activating the brainstem generator for inspiration, which is also involved in the control of gasping. This aspiration reflex (AspR is characterized by spasmodic inspiration without subsequent active expiration and can be elicited during agonal gasping, caused by brainstem trans-sections in cats. Stimulation of the larynx can activate the generator for expiration to evoke the expiration reflex, manifesting with prompt expiration without preceding inspiration. Stimulation of the oro-pharynx and lower airways provokes the cough reflex which results from activating of both generators. The powerful potential of the AspR resembling auto-resuscitation by gasping can influence the control mechanisms of vital functions, mediating reversal of various functional disorders.The AspR in cats interrupted hypoxic apnea, laryngo- and bronchospasm, apneusis and even transient asphyxic coma, and can normalize various hypo- and hyper-functional disorders. Introduction of a nasogastric catheter evoked similar spasmodic inspirations in premature infants and interrupted hiccough attacks in adults. Coughing on demand can prevent anaphylactic shock and resuscitate the pertinent subject. Sniff representing nasal inspiratory pressure and maximal inspiratory and expiratory pressures are voluntary counterparts of airway reflexes, and are useful for diagnosis and therapy of various cardio-respiratory and neuromuscular disorders.

The Effects of Two Different Stretching Programs on Balance Control and Motor Neuron Excitability

Science.gov (United States)

Kaya, Fatih; Biçer, Bilal; Yüktasir, Bekir; Willems, Mark E. T.; Yildiz, Nebil

2018-01-01

We examined the effects of training (4d/wk for 6 wks) with static stretching (SS) or contract-relax proprioceptive neuromuscular facilitation (PNF) on static balance time and motor neuron excitability. Static balance time, H[subscript max]/M[subscript max] ratios and H-reflex recovery curves (HRRC) were measured in 28 healthy subjects (SS: n = 10,…

Reflex vocal fold adduction in the porcine model: the effects of stimuli delivered to various sensory nerves.

Science.gov (United States)

Woo, Jeong-Soo; Hundal, Jagdeep S; Sasaki, Clarence T; Abdelmessih, Mikhail W; Kelleher, Stephen P

2008-10-01

The aim of this study was to identify a panel of sensory nerves capable of eliciting an evoked glottic closure reflex (GCR) and to quantify the glottic closing force (GCF) of these responses in a porcine model. In 5 pigs, the internal branch of the superior laryngeal nerve (iSLN) and the trigeminal, pharyngeal plexus, glossopharyngeal, radial, and intercostal nerves were surgically isolated and electrically stimulated. During stimulation of each nerve, the GCR was detected by laryngeal electromyography and the GCF was measured with a pressure transducer. The only nerve that elicited the GCR in the 5 pigs was the iSLN. The average GCF was 288.9 mm Hg. This study demonstrates that the only afferent nerve that elicits the GCR in pigs is the iSLN, and that it should remain the focus of research for the rehabilitation of patients with absent or defective reflex vocal fold adduction.

Modulation of the masseteric reflex by gastric vagal afferents.

Science.gov (United States)

Pettorossi, V E

1983-04-01

Several investigations have shown that the vagal nerve can affect the reflex responses of the masticatory muscles acting at level either of trigeminal motoneurons or of the mesencephalic trigeminal nucleus (MTN). The present experiments have been devoted to establish the origin of the vagal afferent fibres involved in modulating the masseteric reflex. In particular, the gastric vagal afferents were taken into consideration and selective stimulations of such fibres were performed in rabbit. Conditioning electrical stimulation of truncus vagalis ventralis (TVV) reduced the excitability of the MTN cells as shown by a decrease of the antidromic response recorded from the semilunar ganglion and elicited by MTN single-shock electrical stimulation. Sympathetic and cardiovascular influences were not involved in these responses. Mechanical stimulation of gastric receptors, by means of gastric distension, clearly diminished the amplitude of twitch tension of masseteric reflex and inhibited the discharge frequency of proprioceptive MTN units. The effect was phasic and depended upon the velocity of distension. Thus the sensory volleys originating from rapid adapting receptors reach the brain stem through vagal afferents and by means of a polysynaptic connection inhibits the masseteric reflex at level of MTN cells.

Trigeminal cardiac reflex and cerebral blood flow regulation

Directory of Open Access Journals (Sweden)

Dominga Lapi

2016-10-01

Full Text Available The stimulation of some facial regions is known to trigger the trigemino-cardiac reflex: the main stimulus is represented by the contact of the face with water. This phenomenon called diving reflex induces a set of reactions in the cardiovascular and respiratory systems occurring in all mammals, especially marine (whales, seals. During the immersion of the face in the water, the main responses are aimed at reducing the oxygen consumption of the organism. Accordingly reduction in heart rate, peripheral vasoconstriction, blood pooling in certain organs, especially the heart and brain, and an increase in blood pressure have been reported. Moreover, the speed and intensity of the reflex is inversely proportional to the temperature of the water: more cold the water, more reactions as described are strong. In the case of deep diving an additional effect, such as blood deviation, has been reported: the blood is requested within the lungs, to compensate for the increase in the external pressure, preventing them from collapsing.The trigeminal-cardiac reflex is not just confined to the diving reflex; recently it has been shown that a brief proprioceptive stimulation (10 min by jaw extension in rats produces interesting effects both at systemic and cerebral level, reducing the arterial blood pressure and vasodilating the pial arterioles. The arteriolar dilation is associated with rhythmic diameter changes characterized by an increase in the endothelial activity. Fascinating the stimulation of trigeminal nerve is able to activated the nitric oxide release by vascular endothelial. Therefore the aim of this review was to highlight the effects due to trigeminal cardiac reflex induced by a simple mandibular extension, because produced opposite effects compared to those elicited by the diving reflex as it induces hypotension and modulation of cerebral arteriolar tone.

Increase in H-reflex gain following 1 week of immobilization

DEFF Research Database (Denmark)

Jensen, Jesper Lundbye; Sørensen, Mie; Nielsen, Jens Bo

It is well established that motor experience induces structural and functional plasticity within the central nervous system. It is less well investigated whether reduced motor activity in relation to immobilization is also associated with plastic neuronal changes. The present experiment examined ...... removal all measurements had returned to preimmobilization levels. These results show that immobilization of only one week duration is associated with reversible adaptive changes in the gain of the central part of the monosynaptic stretch reflex....

Muscular reflexes elicited by electrical stimulation of the anterior cruciate ligament in humans

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Dyhre-Poulsen, P; Krogsgaard, M R

2000-01-01

no sign of ACL disease, thin wire electrodes were inserted into the proximal and mid parts of the ACL. Postoperatively, the sensory nerve fibers inside the ACL were stimulated electrically while motor activity in the knee muscles was recorded using electromyography. In seven of the eight patients......, a muscular contraction of the semitendinosus muscle could be elicited with stimulus trains consisting of at least two stimuli. The latency was 95 +/- 35 ms. Stimulation during isometric contraction of either extensor or flexor muscles elicited a short, complete inhibition of the muscle activity...

Altered Neuromodulatory Drive May Contribute to Exaggerated Tonic Vibration Reflexes in Chronic Hemiparetic Stroke

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Jacob G. McPherson

2018-04-01

Full Text Available Exaggerated stretch-sensitive reflexes are a common finding in elbow flexors of the contralesional arm in chronic hemiparetic stroke, particularly when muscles are not voluntarily activated prior to stretch. Previous investigations have suggested that this exaggeration could arise either from an abnormal tonic ionotropic drive to motoneuron pools innervating the paretic limbs, which could bring additional motor units near firing threshold, or from an increased influence of descending monoaminergic neuromodulatory pathways, which could depolarize motoneurons and amplify their responses to synaptic inputs. However, previous investigations have been unable to differentiate between these explanations, leaving the source(s of this excitability increase unclear. Here, we used tonic vibration reflexes (TVRs during voluntary muscle contractions of increasing magnitude to infer the sources of spinal motor excitability in individuals with chronic hemiparetic stroke. We show that when the paretic and non-paretic elbow flexors are preactivated to the same percentage of maximum prior to vibration, TVRs remain significantly elevated in the paretic arm. We also show that the rate of vibration-induced torque development increases as a function of increasing preactivation in the paretic limb, even though the amplitude of vibration-induced torque remains conspicuously unchanged as preactivation increases. It is highly unlikely that these findings could be explained by a source that is either purely ionotropic or purely neuromodulatory, because matching preactivation should control for the effects of a potential ionotropic drive (and lead to comparable tonic vibration reflex responses between limbs, while a purely monoaminergic mechanism would increase reflex magnitude as a function of preactivation. Thus, our results suggest that increased excitability of motor pools innervating the paretic limb post-stroke is likely to arise from both ionotropic and

Does diurnal variation in cough reflex testing exist in healthy young adults?

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Perry, Sarah; Huckabee, Maggie-Lee

2017-05-01

The aim of this study was to investigate whether diurnal variation in cough reflex sensitivity exists in healthy young adults when a tidal-breathing method is used. Fifty-three participants (19-37 years) underwent cough reflex testing on two occasions: once in the morning (between 9 am - midday) and once in the afternoon (between 2-5 pm). The order of testing was counter-balanced. Within each assessment, participants inhaled successively higher citric acid concentrations via a facemask, with saline solution randomly interspersed to control for a placebo response. The lowest concentration that elicited a reflexive cough response was recorded. Morning cough thresholds (mean=0.6mol/L) were not different from afternoon cough thresholds (mean=0.6mol/L), p=0.16, T=101, r=-0.14. We found no evidence of diurnal variability in cough reflex testing. There was, however, an order effect irrespective of time of day, confirming that healthy participants are able to volitionally modulate their cough response. Copyright © 2017 Elsevier B.V. All rights reserved.

Defensive peripersonal space: the blink reflex evoked by hand stimulation is increased when the hand is near the face.

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Sambo, C F; Liang, M; Cruccu, G; Iannetti, G D

2012-02-01

Electrical stimulation of the median nerve at the wrist may elicit a blink reflex [hand blink reflex (HBR)] mediated by a neural circuit at brain stem level. As, in a Sherringtonian sense, the blink reflex is a defensive response, in a series of experiments we tested, in healthy volunteers, whether and how the HBR is modulated by the proximity of the stimulated hand to the face. Electromyographic activity was recorded from the orbicularis oculi, bilaterally. We observed that the HBR is enhanced when the stimulated hand is inside the peripersonal space of the face, compared with when it is outside, irrespective of whether the proximity of the hand to the face is manipulated by changing the position of the arm (experiment 1) or by rotating the head while keeping the arm position constant (experiment 3). Experiment 2 showed that such HBR enhancement has similar magnitude when the participants have their eyes closed. Experiments 4 and 5 showed, respectively, that the blink reflex elicited by the electrical stimulation of the supraorbital nerve, as well as the N20 wave of the somatosensory evoked potentials elicited by the median nerve stimulation, are entirely unaffected by hand position. Taken together, our results provide compelling evidence that the brain stem circuits mediating the HBR in humans undergo tonic and selective top-down modulation from higher order cortical areas responsible for encoding the location of somatosensory stimuli in external space coordinates. These findings support the existence of a "defensive" peripersonal space, representing a safety margin advantageous for survival.

Muscle activation patterns when passively stretching spastic lower limb muscles of children with cerebral palsy.

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Lynn Bar-On

Full Text Available The definition of spasticity as a velocity-dependent activation of the tonic stretch reflex during a stretch to a passive muscle is the most widely accepted. However, other mechanisms are also thought to contribute to pathological muscle activity and, in patients post-stroke and spinal cord injury can result in different activation patterns. In the lower-limbs of children with spastic cerebral palsy (CP these distinct activation patterns have not yet been thoroughly explored. The aim of the study was to apply an instrumented assessment to quantify different muscle activation patterns in four lower-limb muscles of children with CP. Fifty-four children with CP were included (males/females n = 35/19; 10.8 ± 3.8 yrs; bilateral/unilateral involvement n =  32/22; Gross Motor Functional Classification Score I-IV of whom ten were retested to evaluate intra-rater reliability. With the subject relaxed, single-joint, sagittal-plane movements of the hip, knee, and ankle were performed to stretch the lower-limb muscles at three increasing velocities. Muscle activity and joint motion were synchronously recorded using inertial sensors and electromyography (EMG from the adductors, medial hamstrings, rectus femoris, and gastrocnemius. Muscles were visually categorised into activation patterns using average, normalized root mean square EMG (RMS-EMG compared across increasing position zones and velocities. Based on the visual categorisation, quantitative parameters were defined using stretch-reflex thresholds and normalized RMS-EMG. These parameters were compared between muscles with different activation patterns. All patterns were dominated by high velocity-dependent muscle activation, but in more than half, low velocity-dependent activation was also observed. Muscle activation patterns were found to be both muscle- and subject-specific (p<0.01. The intra-rater reliability of all quantitative parameters was moderate to good. Comparing RMS-EMG between

Peripheral δ-opioid receptors attenuate the exercise pressor reflex.

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Leal, Anna K; Yamauchi, Katsuya; Kim, Joyce; Ruiz-Velasco, Victor; Kaufman, Marc P

2013-10-15

In rats with ligated femoral arteries, the exercise pressor reflex is exaggerated, an effect that is attenuated by stimulation of peripheral μ-opioid receptors on group IV metabosensitive afferents. In contrast, δ-opioid receptors are expressed mostly on group III mechanosensitive afferents, a finding that prompted us to determine whether stimulation of these opioid receptors could also attenuate the exaggerated exercise pressor reflex in "ligated" rats. We found femoral arterial injection of [D-Pen2,D-Pen5]enkephalin (DPDPE; 1.0 μg), a δ-opioid agonist, significantly attenuated the pressor and cardioaccelerator components of the exercise pressor reflex evoked by hindlimb muscle contraction in both rats with ligated and patent femoral arteries. DPDPE significantly decreased the pressor responses to muscle mechanoreflex activation, evoked by tendon stretch, in ligated rats only. DPDPE (1.0 μg) had no effect in either group on the pressor and cardioaccelerator responses to capsaicin (0.2 μg), which primarily stimulates group IV afferents. DPDPE (1.0 μg) had no effect on the pressor and cardioaccelerator responses to lactic acid (24 mM), which stimulates group III and IV afferents, in rats with patent femoral arteries but significantly decreased the pressor response in ligated rats. Western blots revealed the amount of protein comprising the δ-opioid receptor was greater in dorsal root ganglia innervating hindlimbs with ligated femoral arteries than in dorsal root ganglia innervating hindlimbs with patent femoral arteries. Our findings support the hypothesis that stimulation of δ-opioid receptors on group III afferents attenuated the exercise pressor reflex.

Evaluation of cranial tibial and extensor carpi radialis reflexes before and after anesthetic block in cats.

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Tudury, Eduardo Alberto; de Figueiredo, Marcella Luiz; Fernandes, Thaiza Helena Tavares; Araújo, Bruno Martins; Bonelli, Marília de Albuquerque; Diogo, Camila Cardoso; Silva, Amanda Camilo; Santos, Cássia Regina Oliveira; Rocha, Nadyne Lorrayne Farias Cardoso

2017-02-01

Objectives This study aimed to test the extensor carpi radialis and cranial tibial reflexes in cats before and after anesthetic block of the brachial and lumbosacral plexus, respectively, to determine whether they depend on a myotatic reflex arc. Methods Fifty-five cats with a normal neurologic examination that were referred for elective gonadectomy were divided into group 1 (29 cats) for testing the extensor carpi radialis reflex, and group 2 (26 cats) for testing the cranial tibial reflex. In group 1, the extensor carpi radialis reflex was tested after anesthetic induction and 15 mins after brachial plexus block with lidocaine. In group 2, the cranial tibial, withdrawal and patellar reflexes were elicited in 52 hindlimbs and retested 15 mins after epidural anesthesia. Results In group 1, before the anesthetic block, 55.17% of the cats had a decreased and 44.83% had a normal extensor carpi radialis reflex. After the block, 68.96% showed a decreased and 27.59% a normal reflex. No cat had an increased or absent reflex before anesthetic block. In group 2, prior to the anesthetic block, 15.38% of the cats had a decreased cranial tibial reflex and 84.62% had a normal response, whereas after the block it was decreased in 26.92% and normal in 73.08% of the cats. None of the cats had an increased or absent reflex. Regarding the presence of both reflexes before and after anesthetic block, there was no significant difference at 1% ( P = 0.013). Conclusions and relevance The extensor carpi radialis and cranial tibial reflexes in cats are not strictly myotatic reflexes, as they are independent of the reflex arc, and may be idiomuscular responses. Therefore, they are not reliable for neurologic examination in this species.

Acute effects of 15min static or contract-relax stretching modalities on plantar flexors neuromuscular properties.

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Babault, Nicolas; Kouassi, Blah Y L; Desbrosses, Kevin

2010-03-01

The present study aimed to investigate the immediate effects of 15 min static or sub-maximal contract-relax stretching modalities on the neuromuscular properties of plantar flexor muscles. Ten male volunteers were tested before and immediately after 15 min static or contract-relax stretching programs of plantar flexor muscles (20 stretches). Static stretching consisted in 30s stretches to the point of discomfort. For the contract-relax stretching modality, subjects performed 6s sub-maximal isometric plantar flexion before 24s static stretches. Measurements included maximal voluntary isometric torque (MVT) and the corresponding electromyographic activity of soleus (SOL) and medial gastrocnemius (MG) muscles (RMS values), as well as maximal peak torque (Pt) elicited at rest by single supramaximal electrical stimulation of the tibial nerve. After 15 min stretching, significant MVT and SOL RMS decreases were obtained (-6.9+/-11.6% and -6.5+/-15.4%, respectively). No difference was obtained between stretching modalities. Pt remained unchanged after stretching. MG RMS changes were significantly different between stretching modalities (-9.4+/-18.3% and +3.5+/-11.6% after static and contract-relax stretching modalities, respectively). These findings indicated that performing 15 min static or contract-relax stretching had detrimental effects on the torque production capacity of plantar flexor muscles and should be precluded before competition. Mechanisms explaining this alteration seemed to be stretch modality dependent. Copyright 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Barriers to performing stretching exercises among Korean-Chinese female migrant workers in Korea.

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Lee, Hyeonkyeong; Wilbur, JoEllen; Chae, Duckhee; Lee, Kyongeun; Lee, Meenhye

2015-01-01

The purpose of this study was to investigate the barriers to performing stretching exercise experienced by Korean-Chinese female migrant workers during a community-based 12-week stretching exercise intervention trial. Qualitative secondary data analysis was conducted using telephone counseling interview transcripts from 27 middle-aged, Korean-Chinese migrant women workers. A semistructured interview question asking barriers to performing stretching exercise was given to women who did not adhere to recommended stretching exercise. During the 12-week home-based stretching exercise intervention trial, six telephone calls were made to participants biweekly to elicit barriers to performing stretching exercise. Directed content analysis approach was utilized using three barrier categories: intrapersonal, interpersonal, and work-related environmental factors based on the ecological model. Participants experienced an average of 2.5 barriers during the study period. Intrapersonal barriers included lack of time and lack of motivation, and interpersonal barriers included no family to provide support and also a feeling resistance from coworkers. Work-related environmental barriers included frequent job changes, long working hours, lack of rest time, and unpredictable job demands. The findings highlight that migrant workers in Korea face unique work-related difficulties which present barriers to exercise. © 2014 Wiley Periodicals, Inc.

sEMG during Whole-Body Vibration Contains Motion Artifacts and Reflex Activity

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Karin Lienhard

2015-01-01

Full Text Available The purpose of this study was to determine whether the excessive spikes observed in the surface electromyography (sEMG spectrum recorded during whole-body vibration (WBV exercises contain motion artifacts and/or reflex activity. The occurrence of motion artifacts was tested by electrical recordings of the patella. The involvement of reflex activity was investigated by analyzing the magnitude of the isolated spikes during changes in voluntary background muscle activity. Eighteen physically active volunteers performed static squats while the sEMG was measured of five lower limb muscles during vertical WBV using no load and an additional load of 33 kg. In order to record motion artifacts during WBV, a pair of electrodes was positioned on the patella with several layers of tape between skin and electrodes. Spectral analysis of the patella signal revealed recordings of motion artifacts as high peaks at the vibration frequency (fundamental and marginal peaks at the multiple harmonics were observed. For the sEMG recordings, the root mean square of the spikes increased with increasing additional loads (p < 0.05, and was significantly correlated to the sEMG signal without the spikes of the respective muscle (r range: 0.54 - 0.92, p < 0.05. This finding indicates that reflex activity might be contained in the isolated spikes, as identical behavior has been found for stretch reflex responses evoked during direct vibration. In conclusion, the spikes visible in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activity.

Oral sapropterin augments reflex vasoconstriction in aged human skin through noradrenergic mechanisms.

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Stanhewicz, Anna E; Alexander, Lacy M; Kenney, W Larry

2013-10-01

Reflex vasoconstriction is attenuated in aged skin due to a functional loss of adrenergic vasoconstriction. Bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for catecholamine synthesis, is reduced with aging. Locally administered BH4 increases vasoconstriction through adrenergic mechanisms in aged human skin. We hypothesized that oral sapropterin (Kuvan, a pharmaceutical BH4) would augment vasoconstriction elicited by whole-body cooling and tyramine perfusion in aged skin. Ten healthy subjects (age 75 ± 2 yr) ingested sapropterin (10 mg/kg) or placebo in a randomized, double-blind crossover design. Venous blood samples were collected prior to, and 3 h following ingestion. Three intradermal microdialysis fibers were placed in the forearm skin for local delivery of 1) lactated Ringer, 2) 5 mM BH4, and 3) 5 mM yohimbine + 1 mM propranolol (Y+P; to inhibit adrenergic vasoconstriction). Red cell flux was measured at each site by laser-Doppler flowmetry (LDF) as reflex vasoconstriction was induced by lowering and then clamping whole-body skin temperature (Tsk) using a water-perfused suit. Following whole-body cooling, subjects were rewarmed and 1 mM tyramine was perfused at each site to elicit endogenous norepinephrine release from the perivascular nerve terminal. Cutaneous vascular conductance was calculated as CVC = LDF/mean arterial pressure and expressed as change from baseline (ΔCVC). Plasma BH4 was elevated 3 h after ingestion of sapropterin (43.8 ± 3 vs. 19.1 ± 2 pmol/ml; P effect on reflex vasoconstriction at the BH4-perfused or Y+P-perfused sites. Sapropterin increased pharmacologically induced vasoconstriction at the Ringer site (-0.19 ± 0.03 vs. -0.08 ± 0.02 ΔCVC; P = 0.01). There was no difference in pharmacologically induced vasoconstriction between treatments at the BH4-perfused site (-0.16 ± 0.04 vs. -0.14 ± 0.03 ΔCVC; P = 0.60) or the Y+P-perfused site (-0.05 ± 0.02 vs.-0.06 ± 0.02 ΔCVC; P = 0.79). Sapropterin increases

The mechano-gated channel inhibitor GsMTx4 reduces the exercise pressor reflex in rats with ligated femoral arteries.

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Copp, Steven W; Kim, Joyce S; Ruiz-Velasco, Victor; Kaufman, Marc P

2016-05-01

Mechanical and metabolic stimuli arising from contracting muscles evoke the exercise pressor reflex. This reflex is greater in a rat model of simulated peripheral arterial disease in which a femoral artery is chronically ligated than it is in rats with freely perfused femoral arteries. The role played by the mechanically sensitive component of the exaggerated exercise pressor reflex in ligated rats is unknown. We tested the hypothesis that the mechano-gated channel inhibitor GsMTx4, a relatively selective inhibitor of mechano-gated Piezo channels, reduces the exercise pressor reflex in decerebrate rats with ligated femoral arteries. Injection of 10 μg of GsMTx4 into the arterial supply of the hindlimb reduced the pressor response to Achilles tendon stretch (a purely mechanical stimulus) but had no effect on the pressor responses to intra-arterial injection of α,β-methylene ATP or lactic acid (purely metabolic stimuli). Moreover, injection of 10 μg of GsMTx4 into the arterial supply of the hindlimb reduced both the integrated pressor area (control 535 ± 21, GsMTx4 218 ± 24 mmHg·s; P reflex contributes to the exaggerated exercise pressor reflex during intermittent hindlimb muscle contractions in rats with ligated femoral arteries. Copyright © 2016 the American Physiological Society.

Dose-dependent opposite effects of gabapentin on the depressive action of morphine on a C-fibre reflex in the rat.

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Pollin, Bernard; Roy-Ledoux, Randy; le Bars, Daniel; Adam, Frédéric

2011-09-01

Gabapentin is a structural analogue of gamma-amino-butyric acid with anticonvulsant activity. Recently, indications for its use were extended to the management of acute pain in the postoperative period. The effects of pre-administration of gabapentin on the depressive action of intravenous morphine were studied on the C-fibre reflex elicited by a wide range of stimulus intensities. The reflex was elicited by electrical stimulation of the sural nerve and recorded from the ipsilateral biceps femoris muscle in halothane anaesthetized rats with either an intact neuraxis or a brainstem previously transected at the level of the obex. As previously reported, 6 mg/kg intravenous morphine both increased the threshold and decreased the slope of the stimulus-response recruitment curve. The C-fibre reflex was not modified following intravenous gabapentin. Gabapentin pre-treatment at lower doses (0.01-7.5 mg/kg) not only antagonized the depressive effect of morphine, but caused facilitation of the reflex. At higher doses (10-50 mg/kg), gabapentin pre-treatment potentiated the depressive effect of morphine. In obex-transected rats, the facilitation of the C-fibre reflex, seen following 1 mg/kg gabapentin and 6 mg/kg morphine, disappeared and was replaced by a strong reinforcement of the depressive effect of morphine. It is concluded that a strong synergy between the effects of gabapentin and morphine can be seen at the spinal level. However, radically opposite effects with supraspinal origins thwart this mechanism. From the clinical standpoint, these results incite cautiousness in the use of combinations of gabapentin and opioids. Copyright © 2011. Published by Elsevier Ltd.

Modulation of the stretch reflex arc to improve functional recovery after peripheral nerve injury

OpenAIRE

Arbat i Plana, Ariadna

2016-01-01

Després d'una lesió del sistema nerviós perifèric, aquest té la capacitat de regenerar però la seva recuperació funcional sol ser limitada, principalment degut a la inespecificitat de la reinnervació dels òrgans perifèrics i als canvis plàstics maladaptatius de la circuiteria espinal. En aquesta tesi hem volgut modular els canvis a la circuiteria espinal del reflex d'estirament per poder millorar la recuperació funcional després de lesions del nervi perifèric en un model animal. En primer llo...

Turtle Flexion Reflex Motor Patterns Show Windup, Mediated Partly by L-type Calcium Channels

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Keith P. Johnson

2017-10-01

Full Text Available Windup is a form of multisecond temporal summation in which identical stimuli, delivered seconds apart, trigger increasingly strong neuronal responses. L-type Ca2+ channels have been shown to play an important role in the production of windup of spinal cord neuronal responses, initially in studies of turtle spinal cord and later in studies of mammalian spinal cord. L-type Ca2+ channels have also been shown to contribute to windup of limb withdrawal reflex (flexion reflex in rats, but flexion reflex windup has not previously been described in turtles and its cellular mechanisms have not been studied. We studied windup of flexion reflex motor patterns, evoked with weak mechanical and electrical stimulation of the dorsal hindlimb foot skin and assessed via a hip flexor (HF nerve recording, in spinal cord-transected and immobilized turtles in vivo. We found that an L-type Ca2+ channel antagonist, nifedipine, applied at concentrations of 50 μM or 100 μM to the hindlimb enlargement spinal cord, significantly reduced windup of flexion reflex motor patterns, while lower concentrations of nifedipine had no such effect. Nifedipine similarly reduced the amplitude of an individual flexion reflex motor pattern evoked by a stronger mechanical stimulus, in a dose-dependent manner, suggesting that L-type Ca2+ channels contribute to each flexion reflex as well as to multisecond summation of flexion reflex responses in turtles. We also found that we could elicit flexion reflex windup consistently using a 4-g von Frey filament, which is not usually considered a nociceptive stimulus. Thus, it may be that windup can be evoked by a wide range of tactile stimuli and that L-type calcium channels contribute to multisecond temporal summation of diverse tactile stimuli across vertebrates.

Involvement of ERK phosphorylation in brainstem neurons in modulation of swallowing reflex in rats

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Tsujimura, Takanori; Kondo, Masahiro; Kitagawa, Junichi; Tsuboi, Yoshiyuki; Saito, Kimiko; Tohara, Haruka; Ueda, Koichiro; Sessle, Barry J; Iwata, Koichi

2009-01-01

In order to evaluate the neuronal mechanisms underlying functional abnormalities of swallowing in orofacial pain patients, this study investigated the effects of noxious orofacial stimulation on the swallowing reflex, phosphorylated extracellular signal-regulated kinase (pERK) and γ-aminobutyric acid (GABA) immunohistochemical features in brainstem neurons, and also analysed the effects of brainstem lesioning and of microinjection of GABA receptor agonist or antagonist into the nucleus tractus solitarii (NTS) on the swallowing reflex in anaesthetized rats. The swallowing reflex elicited by topical administration of distilled water to the pharyngolaryngeal region was inhibited after capsaicin injection into the facial (whisker pad) skin or lingual muscle. The capsaicin-induced inhibitory effect on the swallowing reflex was itself depressed after the intrathecal administration of MAPK kinase (MEK) inhibitor. No change in the capsaicin-induced inhibitory effect was observed after trigeminal spinal subnucleus caudalis lesioning, but the inhibitory effect was diminished by paratrigeminal nucleus (Pa5) lesioning. Many pERK-like immunoreactive neurons in the NTS showed GABA immunoreactivity. The local microinjection of the GABAA receptor agonist muscimol into the NTS produced a significant reduction in swallowing reflex, and the capsaicin-induced depression of the swallowing reflex was abolished by microinjection of the GABAA receptor antagonist bicuculline into the NTS. The present findings suggest that facial skin–NTS, lingual muscle–NTS and lingual muscle–Pa5–NTS pathways are involved in the modulation of swallowing reflex by facial and lingual pain, respectively, and that the activation of GABAergic NTS neurons is involved in the inhibition of the swallowing reflex following noxious stimulation of facial and intraoral structures. PMID:19124539

Involvement of ERK phosphorylation in brainstem neurons in modulation of swallowing reflex in rats.

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Tsujimura, Takanori; Kondo, Masahiro; Kitagawa, Junichi; Tsuboi, Yoshiyuki; Saito, Kimiko; Tohara, Haruka; Ueda, Koichiro; Sessle, Barry J; Iwata, Koichi

2009-02-15

In order to evaluate the neuronal mechanisms underlying functional abnormalities of swallowing in orofacial pain patients, this study investigated the effects of noxious orofacial stimulation on the swallowing reflex, phosphorylated extracellular signal-regulated kinase (pERK) and gamma-aminobutyric acid (GABA) immunohistochemical features in brainstem neurons, and also analysed the effects of brainstem lesioning and of microinjection of GABA receptor agonist or antagonist into the nucleus tractus solitarii (NTS) on the swallowing reflex in anaesthetized rats. The swallowing reflex elicited by topical administration of distilled water to the pharyngolaryngeal region was inhibited after capsaicin injection into the facial (whisker pad) skin or lingual muscle. The capsaicin-induced inhibitory effect on the swallowing reflex was itself depressed after the intrathecal administration of MAPK kinase (MEK) inhibitor. No change in the capsaicin-induced inhibitory effect was observed after trigeminal spinal subnucleus caudalis lesioning, but the inhibitory effect was diminished by paratrigeminal nucleus (Pa5) lesioning. Many pERK-like immunoreactive neurons in the NTS showed GABA immunoreactivity. The local microinjection of the GABA(A) receptor agonist muscimol into the NTS produced a significant reduction in swallowing reflex, and the capsaicin-induced depression of the swallowing reflex was abolished by microinjection of the GABA(A) receptor antagonist bicuculline into the NTS. The present findings suggest that facial skin-NTS, lingual muscle-NTS and lingual muscle-Pa5-NTS pathways are involved in the modulation of swallowing reflex by facial and lingual pain, respectively, and that the activation of GABAergic NTS neurons is involved in the inhibition of the swallowing reflex following noxious stimulation of facial and intraoral structures.

Cervico-ocular Reflex Is Increased in People With Nonspecific Neck Pain.

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de Vries, Jurryt; Ischebeck, Britta K; Voogt, Lennard P; Janssen, Malou; Frens, Maarten A; Kleinrensink, Gert-Jan; van der Geest, Jos N

2016-08-01

Neck pain is a widespread complaint. People experiencing neck pain often present an altered timing in contraction of cervical muscles. This altered afferent information elicits the cervico-ocular reflex (COR), which stabilizes the eye in response to trunk-to-head movements. The vestibulo-ocular reflex (VOR) elicited by the vestibulum is thought to be unaffected by afferent information from the cervical spine. The aim of the study was to measure the COR and VOR in people with nonspecific neck pain. This study utilized a cross-sectional design in accordance with the STROBE statement. An infrared eye-tracking device was used to record the COR and the VOR while the participant was sitting on a rotating chair in darkness. Eye velocity was calculated by taking the derivative of the horizontal eye position. Parametric statistics were performed. The mean COR gain in the control group (n=30) was 0.26 (SD=0.15) compared with 0.38 (SD=0.16) in the nonspecific neck pain group (n=37). Analyses of covariance were performed to analyze differences in COR and VOR gains, with age and sex as covariates. Analyses of covariance showed a significantly increased COR in participants with neck pain. The VOR between the control group, with a mean VOR of 0.67 (SD=0.17), and the nonspecific neck pain group, with a mean VOR of 0.66 (SD=0.22), was not significantly different. Measuring eye movements while the participant is sitting on a rotating chair in complete darkness is technically complicated. This study suggests that people with nonspecific neck pain have an increased COR. The COR is an objective, nonvoluntary eye reflex and an unaltered VOR. This study shows that an increased COR is not restricted to patients with traumatic neck pain. © 2016 American Physical Therapy Association.

Human H-reflexes are smaller in difficult beam walking than in normal treadmill walking.

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Llewellyn, M; Yang, J F; Prochazka, A

1990-01-01

Hoffman (H) reflexes were elicited from the soleus (SOL) muscle while subjects walked on a treadmill and on a narrow beam (3.5 cm wide, raised 34 cm from the floor). The speed of walking on the treadmill was selected for each subject to match the background activation level of their SOL muscle during beam walking. The normal reciprocal activation pattern of the tibialis anterior and SOL muscles in treadmill walking was replaced by a pattern dominated by co-contraction on the beam. In addition, the step cycle duration was more variable and the time spent in the swing phase was reduced on the beam. The H-reflexes were highly modulated in both tasks, the amplitude being high in the stance phase and low in the swing phase. The H-reflex amplitude was on average 40% lower during beam walking than treadmill walking. The relationship between the H-reflex amplitude and the SOL EMG level was quantified by a regression line relating the two variables. The slope of this line was on average 41% lower in beam walking than treadmill walking. The lower H-reflex gain observed in this study and the high level of fusimotor drive observed in cats performing similar tasks suggest that the two mechanisms which control the excitability of this reflex pathway (i.e. fusimotor action and control of transmission at the muscle spindle to moto-neuron synapse) may be controlled independently.

Stretch Sensor Device

DEFF Research Database (Denmark)

2013-01-01

The invention relates to a method for determining stretch values and movement of body parts, e.g. a foot, by analysing stretch data from a stretch sensor. By analysing data from the stretch sensor it is possible to determine stretch samples which are associated with particular motion phases...

Motricidade reflexa na morte cerebral The reflex activity in the brain death

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Wilson L. Sanvito

1972-03-01

Full Text Available O diagnóstico de morte cerebral está baseado em critérios clínicos, eletrencefalográficos e angiográficos. Do ponto de vista clínico deve ser evidenciado o seguinte quadro: coma profundo, midríase paralítica bilateral, ausência de reação a qualquer estímulo externo, apnéia, arreflexia superficial e profunda. Do ponto de vista eletrencefalográfico são necessários dois registros, separados por um intervalo de 24 horas, evidenciando traçados iselétricos. No presente trabalho são estudados 15 pacientes com morte cerebral comprovada do ponto de vista clínico e eletrencefalográfico. Em 8 pacientes havia persistência de atividade reflexa durante a fase de morte cerebral (reflexos profundos e/ou superficiais. Fenômenos de automatismos medulares também foram verificados em 3 pacientes.The diagnosis of brain death is based in clinical, electroencephalographic and angiographic data. The criteria for diagnosis of brain death are: deep coma with unreceptivity and unresponsiveness, no movements or breathing (the patient's respiration must be maintained artificially, bilateral dilated and fixed pupils, absence of corneal reflexes, no response to caloric test, absence of deep tendon reflexes and of the superficial abdominal and plantar reflexes, isoelectric EEG maintained for twenty-four hours. The purpose of this study was to observe the natural clinical courses of 15 patients with brain death, specially the data concerning the deep and superficial reflexes. From 15 patients fulfilling the criteria of brain death, 8 maintained spinal reflexes up to the time of cardiac arrest; in five of these patients the superficial abdominal reflexes were present and the reflexes of spinal automatism could be elicited. These results show that the absence of deep and superficial reflexes can't be considered as essencial for the diagnosis of brain death.

Stretching

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... after a workout. Stretching still can be a beneficial activity after you have sufficiently warmed up. The ... light aerobic activity and stretching. If you're running at a quick pace, you can slow down ...

Increased excitability of spinal pain reflexes and altered frequency-dependent modulation in the dopamine D3-receptor knockout mouse.

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Keeler, Benjamin E; Baran, Christine A; Brewer, Kori L; Clemens, Stefan

2012-12-01

Frequency-dependent modulation and dopamine (DA) receptors strongly modulate neural circuits in the spinal cord. Of the five known DA receptor subtypes, the D3 receptor has the highest affinity to DA, and D3-mediated actions are mainly inhibitory. Using an animal model of spinal sensorimotor dysfunction, the D3 receptor knockout mouse (D3KO), we investigated the physiological consequences of D3 receptor dysfunction on pain-associated signaling pathways in the spinal cord, the initial integration site for the processing of pain signaling. In the D3KO spinal cord, inhibitory actions of DA on the proprioceptive monosynaptic stretch reflex are converted from depression to facilitation, but its effects on longer-latency and pain-associated reflex responses and the effects of FM have not been studied. Using behavioral approaches in vivo, we found that D3KO animals exhibit reduced paw withdrawal latencies to thermal pain stimulation (Hargreaves' test) over wild type (WT) controls. Electrophysiological and pharmacological approaches in the isolated spinal cord in vitro showed that constant current stimulation of dorsal roots at a pain-associated frequency was associated with a significant reduction in the frequency-dependent modulation of longer-latency reflex (LLRs) responses but not monosynaptic stretch reflexes (MSRs) in D3KO. Application of the D1 and D2 receptor agonists and the voltage-gated calcium-channel ligand, pregabalin, but not DA, was able to restore the frequency-dependent modulation of the LLR in D3KO to WT levels. Thus we demonstrate that nociception-associated LLRs and proprioceptive MSRs are differentially modulated by frequency, dopaminergics and the Ca(2+) channel ligand, pregabalin. Our data suggest a role for the DA D3 receptor in pain modulation and identify the D3KO as a possible model for increased nociception. Copyright © 2012 Elsevier Inc. All rights reserved.

Cannabinoids facilitate the swallowing reflex elicited by the superior laryngeal nerve stimulation in rats.

Science.gov (United States)

Mostafeezur, Rahman Md; Zakir, Hossain Md; Takatsuji, Hanako; Yamada, Yoshiaki; Yamamura, Kensuke; Kitagawa, Junichi

2012-01-01

Cannabinoids have been reported to be involved in affecting various biological functions through binding with cannabinoid receptors type 1 (CB1) and 2 (CB2). The present study was designed to investigate whether swallowing, an essential component of feeding behavior, is modulated after the administration of cannabinoid. The swallowing reflex evoked by the repetitive electrical stimulation of the superior laryngeal nerve in rats was recorded before and after the administration of the cannabinoid receptor agonist, WIN 55-212-2 (WIN), with or without CB1 or CB2 antagonist. The onset latency of the first swallow and the time intervals between swallows were analyzed. The onset latency and the intervals between swallows were shorter after the intravenous administration of WIN, and the strength of effect of WIN was dose-dependent. Although the intravenous administration of CB1 antagonist prior to intravenous administration of WIN blocked the effect of WIN, the administration of CB2 antagonist did not block the effect of WIN. The microinjection of the CB1 receptor antagonist directly into the nucleus tractus solitarius (NTS) prior to intravenous administration of WIN also blocked the effect of WIN. Immunofluorescence histochemistry was conducted to assess the co-localization of CB1 receptor immunoreactivity to glutamic acid decarboxylase 67 (GAD67) or glutamate in the NTS. CB1 receptor was co-localized more with GAD67 than glutamate in the NTS. These findings suggest that cannabinoids facilitate the swallowing reflex via CB1 receptors. Cannabinoids may attenuate the tonic inhibitory effect of GABA (gamma-aminobuteric acid) neurons in the central pattern generator for swallowing.

History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

Science.gov (United States)

Stubbs, Peter W; Walsh, Lee D; D'Souza, Arkiev; Héroux, Martin E; Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

2018-06-01

In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the

Role played by acid-sensitive ion channels in evoking the exercise pressor reflex.

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Hayes, Shawn G; McCord, Jennifer L; Rainier, Jon; Liu, Zhuqing; Kaufman, Marc P

2008-10-01

The exercise pressor reflex arises from contracting skeletal muscle and is believed to play a role in evoking the cardiovascular responses to static exercise, effects that include increases in arterial pressure and heart rate. This reflex is believed to be evoked by the metabolic and mechanical stimulation of thin fiber muscle afferents. Lactic acid is known to be an important metabolic stimulus evoking the reflex. Until recently, the only antagonist for acid-sensitive ion channels (ASICs), the receptors to lactic acid, was amiloride, a substance that is also a potent antagonist for both epithelial sodium channels as well as voltage-gated sodium channels. Recently, a second compound, A-317567, has been shown to be an effective and selective antagonist to ASICs in vitro. Consequently, we measured the pressor responses to the static contraction of the triceps surae muscles in decerebrate cats before and after a popliteal arterial injection of A-317567 (10 mM solution; 0.5 ml). We found that this ASIC antagonist significantly attenuated by half (Pacid injection into the popliteal artery. In contrast, A-317567 had no effect on the pressor responses to tendon stretch, a pure mechanical stimulus, and to a popliteal arterial injection of capsaicin, which stimulated transient receptor potential vanilloid type 1 channels. We conclude that ASICs on thin fiber muscle afferents play a substantial role in evoking the metabolic component of the exercise pressor reflex.

Being reflexive in qualitative grounded theory: discussion and application of a model of reflexivity.

Science.gov (United States)

Engward, Hilary; Davis, Geraldine

2015-07-01

A discussion of the meaning of reflexivity in research with the presentation of examples of how a model of reflexivity was used in a grounded theory research project. Reflexivity requires the researcher to make transparent the decisions they make in the research process and is therefore important in developing quality in nursing research. The importance of being reflexive is highlighted in the literature in relation to nursing research, however, practical guidance as to how to go about doing research reflexively is not always clearly articulated. This is a discussion paper. The concept of reflexivity in research is explored using the Alvesson and Skoldberg model of reflexivity and practical examples of how a researcher developed reflexivity in a grounded theory project are presented. Nurse researchers are encouraged to explore and apply the concept of reflexivity in their research practices to develop transparency in the research process and to increase robustness in their research. The Alvesson and Skoldberg model is of value in applying reflexivity in qualitative nursing research, particularly in grounded theory research. Being reflexive requires the researcher to be completely open about decisions that are made in the research process. The Alvesson and Skolberg model of reflexivity is a useful model that can enhance reflexivity in the research process. It can be a useful practical tool to develop reflexivity in grounded theory research. © 2015 John Wiley & Sons Ltd.

Stretching & Flexibility: An Interactive Encyclopedia of Stretching. [CD-ROM].

Science.gov (United States)

2002

This CD-ROM offers 140 different stretches in full-motion video sequences. It focuses on the proper techniques for overall physical fitness, injury prevention and rehabilitation, and 23 different sports (e.g., golf, running, soccer, skiing, climbing, football, and baseball). Topics include stretching for sports; stretching awareness and education…

Cannabinoids facilitate the swallowing reflex elicited by the superior laryngeal nerve stimulation in rats.

Directory of Open Access Journals (Sweden)

Rahman Md Mostafeezur

Full Text Available Cannabinoids have been reported to be involved in affecting various biological functions through binding with cannabinoid receptors type 1 (CB1 and 2 (CB2. The present study was designed to investigate whether swallowing, an essential component of feeding behavior, is modulated after the administration of cannabinoid. The swallowing reflex evoked by the repetitive electrical stimulation of the superior laryngeal nerve in rats was recorded before and after the administration of the cannabinoid receptor agonist, WIN 55-212-2 (WIN, with or without CB1 or CB2 antagonist. The onset latency of the first swallow and the time intervals between swallows were analyzed. The onset latency and the intervals between swallows were shorter after the intravenous administration of WIN, and the strength of effect of WIN was dose-dependent. Although the intravenous administration of CB1 antagonist prior to intravenous administration of WIN blocked the effect of WIN, the administration of CB2 antagonist did not block the effect of WIN. The microinjection of the CB1 receptor antagonist directly into the nucleus tractus solitarius (NTS prior to intravenous administration of WIN also blocked the effect of WIN. Immunofluorescence histochemistry was conducted to assess the co-localization of CB1 receptor immunoreactivity to glutamic acid decarboxylase 67 (GAD67 or glutamate in the NTS. CB1 receptor was co-localized more with GAD67 than glutamate in the NTS. These findings suggest that cannabinoids facilitate the swallowing reflex via CB1 receptors. Cannabinoids may attenuate the tonic inhibitory effect of GABA (gamma-aminobuteric acid neurons in the central pattern generator for swallowing.

The effect of (+)-lysergic acid diethylamide and other drugs on the carotid sinus reflex.

Science.gov (United States)

GINZEL, K H

1958-09-01

In cats, lysergic acid diethylamide (LSD) selectively blocked the reflex blood pressure rise following carotid chemoreceptor stimulation. It also reduced or abolished the chemoreceptor component of the pressor response to occlusion of the common carotid arteries. It did not inhibit the respiratory reflexes arising from the carotid chemoreceptors, unless spontaneous respiration was interfered with as a whole. The site of action was central, probably below the intercollicular level, regardless of whether the drug was administered by the intravenous route or into the lateral ventricle of the brain.LSD did not block the baroreceptor depressor reflex elicited by stimulation of one carotid sinus nerve. LSD frequently caused the systemic pressure to fall, even after vagotomy and atropine, and this effect might account for the occasional reduction of the baroreceptor component of the carotid occlusion response. On the other hand, no relationship was found between the action of LSD on vasomotor tone and its blocking effect on the chemoreceptor pressor reflex.Some derivatives of LSD produced effects similar to those described for LSD, whether or not they possessed a psychotropic action in man, and independently of their efficiency as antagonists to 5-hydroxytryptamine. Of a series of compounds chemically unrelated to LSD, chlorpromazine was found to block the chemoreceptor pressor rise after intracerebroventricular injection.

Developmental axon stretch stimulates neuron growth while maintaining normal electrical activity, intracellular calcium flux, and somatic morphology.

Science.gov (United States)

Loverde, Joseph R; Pfister, Bryan J

2015-01-01

Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18% applied over 5 min. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25% strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

Developmental Axon Stretch Stimulates Neuron Growth While Maintaining Normal Electrical Activity, Intracellular Calcium Flux, and Somatic Morphology

Directory of Open Access Journals (Sweden)

Joseph R Loverde

2015-08-01

Full Text Available Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18 % applied over 5 minutes. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25 % strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

A Novel Stretch Sensor to Measure Venous Hemodynamics

Directory of Open Access Journals (Sweden)

Syrpailyne Wankhar

2018-07-01

Full Text Available Chronic venous insufficiency is a debilitating condition causing varicose veins and venous ulcers. The pathophysiology includes reflux and venous obstruction. The diagnosis is often made by clinical examination and confirmed by Venous Doppler studies. Plethysmography helps to quantitatively examine the reflux and diagnose the burden of deep venous pathology to better understand venous hemodynamics, which is not elicited by venous duplex examination alone. However, most of these tests are qualitative, expensive, and not easily available. In this paper, we demonstrate the potential use of a novel stretch sensor in the assessment of venous hemodynamics during different maneuvers by measuring the change in calf circumference. We designed the stretch sensor by using semiconductor strain gauges pasted onto a small metal bar to form a load cell. The elastic and Velcro material attached to the load cell form a belt. It converts the change in limb circumference to a proportional tension (force of distension when placed around the calf muscle. We recorded the change in limb circumference from arrays of stretch sensors by using an in-house data acquisition system. We calculated the venous volume (VV, venous filling index (VFI, ejection fraction (EF and residual venous volume (RVV on two normal subjects and on two patients to assess venous hemodynamics. The values (VV > 60 ml, VFI 60%, RVV 2ml/s, EF 35% in patients were comparable to those reported in the literature.

Intralimb and Interlimb Cutaneous Reflexes during Locomotion in the Intact Cat.

Science.gov (United States)

Hurteau, Marie-France; Thibaudier, Yann; Dambreville, Charline; Danner, Simon M; Rybak, Ilya A; Frigon, Alain

2018-04-25

When the foot contacts an obstacle during locomotion, cutaneous inputs activate spinal circuits to ensure dynamic balance and forward progression. In quadrupeds, this requires coordinated reflex responses between the four limbs. Here, we investigated the patterns and phasic modulation of cutaneous reflexes in forelimb and hindlimb muscles evoked by inputs from all four limbs. Five female cats were implanted to record muscle activity and to stimulate the superficial peroneal and superficial radial nerves during locomotion. Stimulating these nerves evoked short-, mid-, and longer-latency excitatory and/or inhibitory responses in all four limbs that were phase-dependent. The largest responses were generally observed during the peak activity of the muscle. Cutaneous reflexes during mid-swing were consistent with flexion of the homonymous limb and accompanied by modification of the stance phases of the other three limbs, by coactivating flexors and extensors and/or by delaying push-off. Cutaneous reflexes during mid-stance were consistent with stabilizing the homonymous limb by delaying and then facilitating its push-off and modifying the support phases of the homolateral and diagonal limbs, characterized by coactivating flexors and extensors, reinforcing extensor activity and/or delaying push-off. The shortest latencies of homolateral and diagonal responses were consistent with fast-conducting disynaptic or trisynaptic pathways. Descending homolateral and diagonal pathways from the forelimbs to the hindlimbs had a higher probability of eliciting responses compared with ascending pathways from the hindlimbs to the forelimbs. Thus, in quadrupeds, intralimb and interlimb reflexes activated by cutaneous inputs ensure dynamic coordination of the four limbs, producing a whole-body response. SIGNIFICANCE STATEMENT The skin contains receptors that, when activated, send inputs to spinal circuits, signaling a perturbation. Rapid responses, or reflexes, in muscles of the

Emotion regulation of the affect-modulated startle reflex during different picture categories.

Science.gov (United States)

Conzelmann, Annette; McGregor, Victoria; Pauli, Paul

2015-09-01

Previous studies on emotion regulation of the startle reflex found an increase in startle amplitude from down-, to non-, to up-regulation for pleasant and unpleasant stimuli. We wanted to clarify whether this regulation effect remains stable for different picture categories within pleasant and unpleasant picture sets. We assessed startle amplitude of 31 participants during down-, non-, or up-regulation of feelings elicited by pleasant erotic and adventure and unpleasant victim and threat pictures. Startle amplitude was smaller during adventure and erotic compared to victim and threat pictures and increased from down-, to non-, to up-regulation independently of the picture category. Results indicate that the motivational priming effect on startle modulation elicited by different picture categories is independent of emotion regulation instructions. In addition, the emotion regulation effect is independent of motivational priming effects. © 2015 Society for Psychophysiological Research.

Reflexes in the shoulder muscles elicited from the human coracoacromial ligament

DEFF Research Database (Denmark)

Diederichsen, L.P.; Norregaard, J.; Krogsgaard, M.

2004-01-01

into the CAL in seven normal shoulders. Electric activity was recorded from eight shoulder muscles by surface and intramuscular electrodes. During isometric contractions, electrical stimulation was applied to the CAL at two different stimulus intensities, a weak stimulus (stim-1) and a stronger stimulus (stim...... activity from mechanoreceptors in the coracoacromial ligament (CAL) on the activity of voluntary activated shoulder muscles in healthy humans. In study I, wire electrodes, for electrical stimulation, were inserted into the CAL in eight normal shoulders. In study II, a needle electrode was inserted......-2). In both experiments, electrical stimulation of the CAL elicited a general inhibition in the voluntary activated shoulder muscles. In study I the average latencies (mean+/-SE) of the muscular inhibition were 66+/-4 ms (stim-1) and 62+/-4 ms (stim-2) during isometric flexion and 73+/-3 ms (stim-1...

Etnography and Reflexivity

Directory of Open Access Journals (Sweden)

Mario Cardano

2014-01-01

Full Text Available This essay deals with a relevant and controversial topic – objectivity in ethnographic research. More specifically, I would like to examine how reflexive procedures, more precisely “reflexive account”, can increase the robustness of results gained through an ethnographic research. The essay is organized in five parts. I will start by giving a preliminary definition of the two key concepts which are at the center of the analysis – objectivity and reflexivity. I will then give a brief description of the epistemological framework in which the proposed conceptions of objectivity and reflexivity are located. Thirdly, I move on to consider the epistemic status of ethnographic research, and will emphasize that ethnographies are not just “theory-laden”, as many writers have stated, but also “praxis” or “procedure laden”. In other words, I will stress that it is not only theories which are inevitably embedded in research, influencing how observations can be made; much the same can also be said of the concrete research practices which contribute to determine the experience of the ethnographer and its representation in a text. Fourthly, I will discuss why it is useful to employ reflexive practices, and then immediately afterwards will illustrate the ways in which reflexive descriptions can contribute to greater objectivity of ethnographic accounts. In conclusion, I will discuss a number of objections which have been raised against this use of reflexivity.

The pulse duration of electrical stimulation influences H-reflexes but not corticospinal excitability for tibialis anterior.

Science.gov (United States)

Hindle, Alyssa R; Lou, Jenny W H; Collins, David F

2014-10-01

The afferent volley generated by neuromuscular electrical stimulation (NMES) influences corticospinal (CS) excitability and frequent NMES sessions can strengthen CS pathways, resulting in long-term improvements in function. This afferent volley can be altered by manipulating NMES parameters. Presently, we manipulated one such parameter, pulse duration, during NMES over the common peroneal nerve and assessed the influence on H-reflexes and CS excitability. We hypothesized that compared with shorter pulse durations, longer pulses would (i) shift the H-reflex recruitment curve to the left, relative to the M-wave curve; and (ii) increase CS excitability more. Using 3 pulse durations (50, 200, 1000 μs), M-wave and H-reflex recruitment curves were collected and, in separate experiments, CS excitability was assessed by comparing motor evoked potentials elicited before and after 30 min of NMES. Despite finding a leftward shift in the H-reflex recruitment curve when using the 1000 μs pulse duration, consistent with a larger afferent volley for a given efferent volley, the increases in CS excitability were not influenced by pulse duration. Hence, although manipulating pulse duration can alter the relative recruitment of afferents and efferents in the common peroneal nerve, under the present experimental conditions it is ineffective for maximizing CS excitability for rehabilitation.

Surgical desensitisation of the mechanoreceptors in Müller's muscle relieves chronic tension-type headache caused by tonic reflexive contraction of the occipitofrontalis muscle in patients with aponeurotic blepharoptosis.

Science.gov (United States)

Matsuo, Kiyoshi; Ban, Ryokuya

2013-02-01

Proprioceptively innervated intramuscular connective tissues in Müller's muscle function as exterior mechanoreceptors to induce reflex contraction of the levator and occipitofrontalis muscles. In aponeurotic blepharoptosis, since the levator aponeurosis is disinserted from the tarsus, stretching of the mechanoreceptors in Müller's muscle is increased even on primary gaze to induce phasic and tonic reflexive contraction of the occipitofrontalis muscle. It was hypothesised that in certain patients with aponeurotic blepharoptosis, the presence of tonic reflexive contraction of the occipitofrontalis muscle due to the sensitised mechanoreceptors in Müller's muscle, can cause chronic tension-type headache (CTTH) associated with occipitofrontalis tenderness. To verify this hypothesis, this study evaluated (1) what differentiates patients with CTTH from patients without CTTH, (2) how pharmacological contraction of Müller's smooth muscle fibres as a method for desensitising the mechanoreceptors in Müller's muscle affects electromyographic activity of the frontalis muscle, and (3) how surgical aponeurotic reinsertion to desensitise the mechanoreceptors in Müller's muscle electromyographically or subjectively affects activities of the occipitofrontalis muscle or CTTH. It was found that patients had sustained CTTH when light eyelid closure did not markedly reduce eyebrow elevation. However, pharmacological contraction of Müller's smooth muscle fibres or surgery to desensitise the mechanoreceptor electromyographically reduced the tonic contraction of the occipitofrontalis muscle on primary gaze and subjectively relieved aponeurotic blepharoptosis-associated CTTH. Over-stretching of the mechanoreceptors in Müller's muscle on primary gaze may induce CTTH due to tonic reflexive contraction of the occipitofrontalis muscle. Therefore, surgical desensitisation of the mechanoreceptors in Müller's muscle appears to relieve CTTH.

Gain modulation of the middle latency cutaneous reflex in patients with chronic joint instability after ankle sprain.

Science.gov (United States)

Futatsubashi, Genki; Sasada, Shusaku; Tazoe, Toshiki; Komiyama, Tomoyoshi

2013-07-01

To investigate the neural alteration of reflex pathways arising from cutaneous afferents in patients with chronic ankle instability. Cutaneous reflexes were elicited by applying non-noxious electrical stimulation to the sural nerve of subjects with chronic ankle instability (n=17) and control subjects (n=17) while sitting. Electromyographic (EMG) signals were recorded from each ankle and thigh muscle. The middle latency response (MLR; latency: 70-120 ms) component was analyzed. In the peroneus longus (PL) and vastus lateralis (VL) muscles, linear regression analyses between the magnitude of the inhibitory MLR and background EMG activity showed that, compared to the uninjured side and the control subjects, the gain of the suppressive MLR was increased in the injured side. This was also confirmed by the pooled data for both groups. The degree of MLR alteration was significantly correlated to that of chronic ankle instability in the PL. The excitability of middle latency cutaneous reflexes in the PL and VL is modulated in subjects with chronic ankle instability. Cutaneous reflexes may be potential tools to investigate the pathological state of the neural system that controls the lower limbs in subjects with chronic ankle instability. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Stretch-minimising stream surfaces

KAUST Repository

Barton, Michael; Kosinka, Jin; Calo, Victor M.

2015-01-01

We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these 'stretch-free' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

Stretch-minimising stream surfaces

KAUST Repository

Barton, Michael

2015-05-01

We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these \\'stretch-free\\' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

Reflexivity in qualitative research

DEFF Research Database (Denmark)

Evans, Adam Brian; Nistrup, Anne; Henderson, Hannah

2018-01-01

There has been something of a “reflexive shift” in sociological research. Sociological researchers are increasingly encouraged to be “present” within their work, and to recognize their own role in structuring the entire research process. One way to achieve this is through engagement in reflexive...... practice, that is, to reflect on our own values, beliefs, and biographies. It can be difficult to know exactly how a researcher should engage in these practices, however. Here, we discuss our reflexive practice in two case studies, both which utilized the same figurational theoretical framework...... Kingdom. Reflexive practice in both studies was affected by researcher biographies and by study design. In Study 1, both researchers were reasonably detached from the study context, the theoretical framework was in place from the very beginning, and reflexive practice was embedded in the study design...

Stretching Safely and Effectively

Science.gov (United States)

... shown that stretching immediately before an event weakens hamstring strength. Instead of static stretching, try performing a " ... If you play soccer, for instance, stretch your hamstrings as you're more vulnerable to hamstring strains. ...

Knotting in stretched polygons

International Nuclear Information System (INIS)

Rensburg, E J Janse van; Orlandini, E; Tesi, M C; Whittington, S G

2008-01-01

The knotting in a lattice polygon model of ring polymers is examined when a stretching force is applied to the polygon. By examining the incidence of cut-planes in the polygon, we prove a pattern theorem in the stretching regime for large applied forces. This theorem can be used to examine the incidence of entanglements such as knotting and writhing. In particular, we prove that for arbitrarily large positive, but finite, values of the stretching force, the probability that a stretched polygon is knotted approaches 1 as the length of the polygon increases. In the case of writhing, we prove that for stretched polygons of length n, and for every function f(n)=o(√n), the probability that the absolute value of the mean writhe is less than f(n) approaches 0 as n → ∞, for sufficiently large values of the applied stretching force

On the use of information theory for the analysis of synchronous nociceptive withdrawal reflexes and somatosensory evoked potentials elicited by graded electrical stimulation.

Science.gov (United States)

Arguissain, Federico G; Biurrun Manresa, José A; Mørch, Carsten D; Andersen, Ole K

2015-01-30

To date, few studies have combined the simultaneous acquisition of nociceptive withdrawal reflexes (NWR) and somatosensory evoked potentials (SEPs). In fact, it is unknown whether the combination of these two signals acquired simultaneously could provide additional information on somatosensory processing at spinal and supraspinal level compared to individual NWR and SEP signals. By using the concept of mutual information (MI), it is possible to quantify the relation between electrical stimuli and simultaneous elicited electrophysiological responses in humans based on the estimated stimulus-response signal probability distributions. All selected features from NWR and SEPs were informative in regard to the stimulus when considered individually. Specifically, the information carried by NWR features was significantly higher than the information contained in the SEP features (pinformation carried by the combination of features showed an overall redundancy compared to the sum of the individual contributions. Comparison with existing methods MI can be used to quantify the information that single-trial NWR and SEP features convey, as well as the information carried jointly by NWR and SEPs. This is a model-free approach that considers linear and non-linear correlations at any order and is not constrained by parametric assumptions. The current study introduces a novel approach that allows the quantification of the individual and joint information content of single-trial NWR and SEP features. This methodology could be used to decode and interpret spinal and supraspinal interaction in studies modulating the responsiveness of the nociceptive system. Copyright © 2014 Elsevier B.V. All rights reserved.

[Reflex seizures, cinema and television].

Science.gov (United States)

Olivares-Romero, Jesús

2015-12-16

In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot.

Influence of the stretch wrapping process on the mechanical behavior of a stretch film

Science.gov (United States)

Klein, Daniel; Stommel, Markus; Zimmer, Johannes

2018-05-01

Lightweight construction is an ongoing task in packaging development. Consequently, the stability of packages during transport is gaining importance. This study contributes to the optimization of lightweight packaging concepts regarding their stability. A very widespread packaging concept is the distribution of goods on a pallet whereas a Polyethylene (PE) stretch film stabilizes the lightweight structure during the shipment. Usually, a stretch wrapping machine applies this stretch film to the pallet. The objective of this study is to support packaging development with a method that predicts the result of the wrapping process, based on the mechanical characterization of the stretch film. This result is not only defined by the amount of stretch film, its spatial distribution on the pallet and its internal stresses that result in a containment force. More accurate, this contribution also considers the influence of the deformation history of the stretch film during the wrapping process. By focusing on similarities of stretch wrappers rather than on differences, the influence of generalized process parameters on stretch film mechanics and thereby on pallet stability can be determined experimentally. For a practical use, the predictive method is accumulated in an analytic model of the wrapping process that can be verified experimentally. This paves the way for experimental and numerical approaches regarding the optimization of pallet stability.

ZAG-Otolith: Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control during Variable Radius Centrifugation Following Space Flight

Science.gov (United States)

Wood, S. J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

2009-01-01

Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved with vibrotactile feedback of orientation.

On Reflexive Data Models

Energy Technology Data Exchange (ETDEWEB)

Petrov, S.

2000-08-20

An information system is reflexive if it stores a description of its current structure in the body of stored information and is acting on the base of this information. A data model is reflexive, if its language is meta-closed and can be used to build such a system. The need for reflexive data models in new areas of information technology applications is argued. An attempt to express basic notions related to information systems is made in the case when the system supports and uses meta-closed representation of the data.

Reflexive contraction of the levator palpebrae superioris muscle to involuntarily sustain the effective eyelid retraction through the transverse trigeminal proprioceptive nerve on the proximal Mueller's muscle: verification with evoked electromyography.

Science.gov (United States)

Ban, Ryokuya; Matsuo, Kiyoshi; Osada, Yoshiro; Ban, Midori; Yuzuriha, Shunsuke

2010-01-01

We have proposed a hypothetical mechanism to involuntarily sustain the effective eyelid retraction, which consists of not only voluntary but also reflexive contractions of the levator palpebrae superior muscle (LPSM). Voluntary contraction of fast-twitch fibres of the LPSM stretches the mechanoreceptors in Mueller's muscle to evoke trigeminal proprioception, which induces continuous reflexive contraction of slow-twitch fibres of the LPSM through the trigeminal proprioceptive nerve fibres innervating the mechanoreceptors in Mueller's muscle via the oculomotor neurons, as a tonic trigemino-oculomotor reflex. In the common skeletal mixed muscles, electrical stimulation of the proprioceptive nerve, which apparently connects the mechanoreceptors in muscle spindles to the motoneurons, induces the electromyographic response as the Hoffmann reflex. To verify the presence of the trigemino-oculomotor reflex, we confirmed whether intra-operative electrical simulation of the transverse trigeminal proprioceptive nerve on the proximal Mueller's muscle evokes an electromyographic response in the LPSM under general anaesthesia in 12 patients. An ipsilateral, phasic, short-latency response (latency: 2.8+/-0.3 ms) was induced in the ipsilateral LPSM in 10 of 12 subjects. As successful induction of the short-latency response in the ipsilateral LPSM corresponds to the Hoffmann reflex in the common skeletal mixed muscles, the present study is the first electromyographic verification of the presence of the monosynaptic trigemino-oculomotor reflex to induce reflexive contraction of the LPSM. The presence of the trigemino-oculomotor reflex may elucidate the unexplainable blepharoptosis due to surgery, trauma and tumour, all of which may damage the trigeminal proprioceptive nerve fibres to impair the trigemino-oculomotor reflex. Copyright (c) 2008. Published by Elsevier Ltd.

Passive Stretch Versus Active Stretch on Intervertebral Movement in Non - Specific Neck Pain

International Nuclear Information System (INIS)

Abd El - Aziz, A.H.; Amin, D.I.; Moustafa, I.

2016-01-01

Neck pain is one of the most common and painful musculoskeletal conditions. Point prevalence ranges from 6% to 22% and up to 38% of the elderly population, while lifetime prevalence ranges from 14,2% to 71%. Up till now no randomized study showed the effect between controversy of active and passive stretch on intervertebral movement. The purpose: the current study was to investigate the effect of the passive and active stretch on intervertebral movement in non - specific neck pain. Material and methods: Forty five subjects from both sexes with age range between 18 and 30 years and assigned in three groups, group I (15) received active stretch, ultrasound and TENS. Group II (15) received passive stretch, ultrasound and TENS. Group III (15) received ultrasound and TENS. The radiological assessment was used to measure rotational and translational movement of intervertebral movement before and after treatment. Results: MANOVA test was used for radiological assessment before and after treatment there was significant increase in intervertebral movement in group I as p value =0.0001. Conclusion: active stretch had a effect in increasing the intervertebral movement compared to the passive stretch

Effects of intrathecal or intracerebroventricular administration of nonsteroidal anti-inflammatory drugs on a C-fiber reflex in rats.

Science.gov (United States)

Bustamante, D; Paeile, C; Willer, J C; Le Bars, D

1997-06-01

A C-fiber reflex elicited by electrical stimulation within the territory of the sural nerve was recorded from the ipsilateral biceps femoris muscle in anesthetized rats. The temporal evolution of the response was studied using a constant stimulus intensity (3 times threshold), and recruitment curves were built by varying the stimulus intensity from 0 to 7 times threshold. The intrathecal (i.t.) but not i.c.v. administration of aspirin, indomethacin, ketoprofen and lysine clonixinate resulted in dose-dependent depressions of the C-fiber reflex. In contrast, saline was ineffective. Regardless of the route of administration, the drugs never produced disturbances in heart rate and/or acid-base equilibrium. When a constant level of stimulation was used, 500 microg of aspirin i.t. induced a blockade of the reflex immediately after the injection, followed by a partial recovery. Indomethacin produced a stable depression, which reached 80 to 90% with an i.t. dose of 500 microg. Ketoprofen and lysine clonixinate produced a more stable effect; the highest doses (500 microg) produced a steady-state depression of approximately 50% for approximately 30 min. When the recruitment curves were built with a range of nociceptive stimulus intensities, all of the drugs except for indomethacin produced a dose-dependent decrease in the slopes and the areas under the recruitment curves without major modifications in the thresholds; indomethacin also induced a significant dose-related increase in the threshold. The orders of potency for both stimulation paradigms with the i.t. route were the same, namely aspirin > indomethacin > lysine clonixinate > or = ketoprofen. It is concluded that nonsteroidal anti-inflammatory drugs elicit significant antinociceptive effects at a spinal level, which do not depend on the existence of a hyperalgesic or inflammatory state. Such effects were not seen after injections within the lateral ventricle.

Group Ia afferents likely contribute to short-latency interlimb reflexes in the human biceps femoris muscle

DEFF Research Database (Denmark)

Stevenson, Andrew James Thomas; Kamavuako, Ernest Nlandu; Geertsen, Svend Sparre

2017-01-01

amplitudes (4 vs. 8°) at the same 150°/s velocity (p’s > 0.08). Conclusion: Because fast conducting group Ia muscle spindle afferents are sensitive to changes in muscle stretch velocity, while group II spindle afferents are sensitive to changes in amplitude (Grey et al., JPhysiol., 2001; Matthews, Trends...... Neurosci., 1991), group Ia velocity sensitive muscle spindle afferents likely contribute to the short-latency crossed spinal reflexes in the cBF muscle following iKnee joint rotations. This supports the findings for the short-latency crossed responses in the human soleus muscle (Stubbs & Mrachacz...... neurons in humans, with primary contributions from group Ia muscle spindle afferents....

Neurodevelopmental Reflex Testing in Neonatal Rat Pups.

Science.gov (United States)

Nguyen, Antoinette T; Armstrong, Edward A; Yager, Jerome Y

2017-04-24

Neurodevelopmental reflex testing is commonly used in clinical practice to assess the maturation of the nervous system. Neurodevelopmental reflexes are also referred to as primitive reflexes. They are sensitive and consistent with later outcomes. Abnormal reflexes are described as an absence, persistence, reappearance, or latency of reflexes, which are predictive indices of infants that are at high risk for neurodevelopmental disorders. Animal models of neurodevelopmental disabilities, such as cerebral palsy, often display aberrant developmental reflexes, as would be observed in human infants. The techniques described assess a variety of neurodevelopmental reflexes in neonatal rats. Neurodevelopmental reflex testing offers the investigator a testing method that is not otherwise available in such young animals. The methodology presented here aims to assist investigators in examining developmental milestones in neonatal rats as a method of detecting early-onset brain injury and/or determining the effectiveness of therapeutic interventions. The methodology presented here aims to provide a general guideline for investigators.

Bone conducted vibration activates the vestibulo-ocular reflex in the guinea pig.

Science.gov (United States)

Vulovic, Vedran; Curthoys, Ian S

2011-08-10

The aim of the study was: (a) to test whether short duration (6 ms) 500 Hz bone-conducted vibration (BCV) of the skull in alert head free guinea pigs would elicit eye movements; (b) to test whether these eye movements were vestibular in origin; and (c) to determine whether they corresponded to human eye movements to such stimuli. In this way we sought to establish the guinea pig as an acceptable model for testing the mechanism of the effect BCV on the vestibulo-ocular reflex. Consistent short-latency stimulus-locked responses to BCV were observed. The magnitude of eye displacement was directly related to stimulus intensity as recorded by accelerometers cemented onto the animal's skull. The strongest and most consistent response component was intorsion of both eyes. In lateral-eyed animals intorsion is produced by the combined contraction of the inferior rectus and superior oblique muscles. In humans the same pair of muscles acts to cause depression of the eye. To test whether the movements were vestibular we selectively ablated the vestibular endorgans: 3 of the 8 animals underwent a bilateral intratympanic injection of gentamicin, an ototoxic aminoglycoside antibiotic, to ablate their vestibular receptors. After ablation there was an overall reduction in the magnitude of eye displacement, as well as a reduction in the effectiveness of the BCV stimulus to elicit eye movements. The animals' hearing, as measured by the threshold for auditory brainstem responses, remained unchanged after gentamicin, confirming that the cochlea was not affected. The reduced magnitude of responses after vestibular receptor ablation demonstrates that the eye-movement responses to BCV are probably caused by the stimulation of vestibular receptors, which in turn activate the vestibulo-ocular reflex. Copyright © 2011 Elsevier Inc. All rights reserved.

Cyclic Mechanical Stretch Up-regulates Hepatoma-Derived Growth Factor Expression in Cultured Rat Aortic Smooth Muscle Cells.

Science.gov (United States)

Kao, Ying-Hsien; Chen, Po-Han; Sun, Cheuk-Kwan; Chang, Yo-Chen; Lin, Yu-Chun; Tsai, Ming-Shian; Lee, Po-Huang; Cheng, Cheng-I

2018-02-21

Hepatoma-derived growth factor (HDGF) is a potent mitogen for vascular smooth muscle cells (SMCs) during embryogenesis and injury repair of vessel walls. Whether mechanical stimuli modulate HDGF expression remains unknown. This study aimed at investigating whether cyclic mechanical stretch plays a regulatory role in HDGF expression and regenerative cytokine production in aortic SMCs. A SMC cell line was grown on a silicone-based elastomer chamber with extracellular matrix coatings (either type I collagen or fibronectin) and received cyclic and uni-axial mechanical stretches with 10% deformation at frequency 1 Hz. Morphological observation showed that fibronectin coating provided better cell adhesion and spreading and that consecutive 6 hours of cyclic mechanical stretch remarkably induced reorientation and realignment of SMCs. Western blotting detection demonstrated that continuous mechanical stimuli elicited up-regulation of HDGF and PCNA, a cell proliferative marker. Signal kinetic profiling study indicated that cyclic mechanical stretch induced signaling activity in RhoA/ROCK and PI3K/Akt cascades. Kinase inhibition study further showed that blockade of PI3K activity suppressed the stretch-induced TNF-a, whereas RhoA/ROCK inhibition significantly blunted the IL-6 production and HDGF over-expression. Moreover, siRNA-mediated HDGF gene silencing significantly suppressed constitutive expression of IL-6, but not TNF-α, in SMCs. These findings support the role of HDGF in maintaining vascular expression of IL-6, which has been regarded a crucial regenerative factor for acute vascular injury. In conclusion, cyclic mechanical stretch may maintain constitutive expression of HDGF in vascular walls and be regarded an important biophysical regulator in vascular regeneration. ©2018 The Author(s).

“Clip, move, adjust”: Video editing as reflexive rhythmanalysis in networked publics

DEFF Research Database (Denmark)

Rehder, Mads Middelboe; Pereira, Gabriel; Markham, Annette

2017-01-01

as part of a six-year (and ongoing) study of how youth experience social media (authors). In this larger study, youth produced, among other things, videologs of their experiences, after being trained in auto-elicitation and ethnographic methods (authors). As a further step in reflexive autoethnographic...... analysis, the method we outline consists of asking participants to engage in a phenomenologically grounded analytical editing process of these videologs. In this study, we find that as participants edit their own videos, they add information and depth at a level beyond what we researchers can bring in our...... own analyses. This tool is a productive way to get closer to the granularity of participants’ lived experiences....

Repetitive exposure: Brain and reflex measures of emotion and attention

Science.gov (United States)

Ferrari, Vera; Bradley, Margaret M.; Codispoti, Maurizio; Lang, Peter J.

2010-01-01

Effects of massed repetition on the modulation of the late positive potential elicited during affective picture viewing were investigated in two experiments. Despite a difference in the number of repetitions across studies (from 5 to 30), results were quite similar: the late positive potential continued to be enhanced when viewing emotional, compared to neutral, pictures. On the other hand, massed repetition did prompt a reduction in the late positive potential that was most pronounced for emotional pictures. Startle probe P3 amplitude generally increased with repetition, suggesting diminished attention allocation to repeated pictures. The blink reflex, however, continued to be modulated by hedonic valence, despite massive massed repetition. Taken together, the data suggest that the amplitude of the late positive potential during picture viewing reflects both motivational significance and attention allocation. PMID:20701711

Increased central facilitation of antagonist reciprocal inhibition at the onset of dorsiflexion following explosive strength training

DEFF Research Database (Denmark)

Geertsen, Svend Sparre; Jensen, Jesper Lundbye; Nielsen, Jens Bo

2008-01-01

At the onset of dorsiflexion disynaptic reciprocal inhibition (DRI) of soleus motoneurons is increased to prevent activation of the antagonistic plantar flexors. This is caused by descending facilitation of transmission in the DRI pathway. Because the risk of eliciting stretch reflexes in the ankle...... of the ankle dorsiflexor muscles 3 times a week for 4 wk. Test sessions were conducted before, shortly after, and 2 wk after the training period. The rate of torque development measured at 30, 50, 100, and 200 ms after onset of voluntary explosive isometric dorsiflexion increased by 24-33% (P

Stretch strength of Al-Li alloy sheet

Energy Technology Data Exchange (ETDEWEB)

Sato, K.; Sawa, Y.; Yokoyama, T.; Fujimoto, S. [Science Univ. of Tokyo (Japan). Dept. of Mech. Eng.; Sakamoto, T. [Kobe Steel Works, Tokyo (Japan)

1998-07-01

Stretch test on Al-Li alloy sheet was carried out in stretch rate of 0.01 to 0.2 mm/sec. The limiting stretch depth was measured in various conditions and the following results were obtained. (1) Stretch rate does not affect the limiting stretch depth of Al-Li alloy. (2) The limiting stretch depth is increased with increase of the profile radius. (3) Strain hardening exponent(n-value) and r-value of Lankford do not affect the limiting stretch depth. (4) Rapture pattern in stretch test of Al is {alpha} type rapture and that of Al-Li alloy is straight line type rapture. (orig.) 4 refs.

Charitable giving and reflexive individuals: How personal reflexivity mediates between structure and agency.

Science.gov (United States)

Sanghera, Balihar

2017-03-01

This article examines how individuals are reflexive beings who interpret the world in relation to things that matter to them, and how charitable acts are evaluated and embedded in their lives with different degrees of meaning and importance. Rather than framing the discussion of charitable practices in terms of an altruism/egoism binary or imputing motivations and values to social structures, the article explains how reflexivity is an important and neglected dimension of social practices, and how it interacts with sympathy, sentiments and discourses to shape giving. The study also shows that there are different modes of reflexivity, which have varied effects on charity and volunteering.

[Laryngeal adduction reflex].

Science.gov (United States)

Ptok, M; Bonenberger, S; Miller, S; Kühn, D; Jungheim, M

2014-07-01

Laryngeal Adductor Reflex Background: A rapid closure of the vocal folds is necessary, whenever foreign materials or food particles penetrate into the larynx. Otherwise a passage of these particles into the trachea or the lower respiratory tract would be imminent. An aspiration could mechanically block the respiratory tract and cause severe dyspnoea or cause aspiration pneumonia. For this systematic review a selective literature research in PubMed and Scopus using the keywords "laryngeal adductor reflex" and "vocal fold closure" has been carried out. Apart from the oesophago-glottal and pharyngo-glottal closure reflexes, the laryngeal adductor reflex (LAR) has been investigated in particular. The LAR qualifies as a reflectory laryngeal adductor mechanism and involves early, presumably di- or oligosynaptic ipsilateral LAR1 as well as late polysynaptic ipsi- and contralateral LAR2 components. In clinical routine diagnostic settings of dysphagia, LAR is only assessed qualitatively and usually triggered by air pulses or tactile stimulation. Dysphagiologists often find that not only the laryngeal sensibility in general is impaired, but especially the protective laryngeal adduction mechanism, which results in a higher risk of aspiration. Thus, it appears mandatory to test the LAR not only qualitatively but also quantitatively. Unfortunately a valid and reliable method that can be employed in clinical practice has not yet been put forward. © Georg Thieme Verlag KG Stuttgart · New York.

Atomic Stretch: Optimally bounded real-time stretching and beyond

DEFF Research Database (Denmark)

Jensen, Rasmus Ramsbøl; Nielsen, Jannik Boll

2016-01-01

Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color-modification, co......Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color...

How to determine local stretching and tension in a flow-stretched DNA molecule

DEFF Research Database (Denmark)

Pedersen, Jonas Nyvold; Marie, Rodolphe; Kristensen, Anders

2016-01-01

We determine the nonuniform stretching of and tension in amega base pairs-long fragment of deoxyribonucleic acid (DNA) that is flow stretched in a nanofluidic chip. We use no markers, do not know the contour length of the DNA, and do not have the full DNA molecule inside our field of view. Instead......, we analyze the transverse thermal motion of the DNA. Tension at the center of the DNA adds up to 16 pN, giving almost fully stretched DNA. This method was devised for optical mapping of DNA, specifically, DNA denaturation patterns. It may be useful also for other studies, e.g., DNA......-protein interactions, specifically, their tension dependence. Generally, wherever long strands of DNA—e.g., native DNA extracted from human cells or bacteria—must be stretched with ease for inspection, this method applies....

Effect of chronic and acute cigarette smoking on the pharyngo-upper oesophageal sphincter contractile reflex and reflexive pharyngeal swallow

OpenAIRE

Dua, K; Bardan, E; Ren, J; Sui, Z; Shaker, R

1998-01-01

Background—Cigarette smoking is known to affect adversely the defence mechanisms against gastro-oesophageal reflux. The effect of smoking on the supraoesophageal reflexes that prevent aspiration of gastric contents has not been previously studied. 
Aims—To elucidate the effect of cigarette smoking on two of the supraoesophageal reflexes: the pharyngo-upper oesophageal sphincter (UOS) contractile reflex; and the reflexive pharyngeal swallow. 
Methods—Ten chronic smokers and 10 non-...

Habituation of the orienting reflex and the development of Preliminary Process Theory.

Science.gov (United States)

Barry, Robert J

2009-09-01

The orienting reflex (OR), elicited by an innocuous stimulus, can be regarded as a model of the organism's interaction with its environment, and has been described as the unit of attentional processing. A major determinant of the OR is the novelty of the eliciting stimulus, generally operationalized in terms of its reduction with stimulus repetition, the effects of which are commonly described in habituation terms. This paper provides an overview of a research programme, spanning more than 30 years, investigating psychophysiological aspects of the OR in humans. The major complication in this research is that the numerous physiological measures used as dependent variables in the OR context fail to jointly covary with stimulus parameters. This has led to the development of the Preliminary Process Theory (PPT) of the OR to accommodate the complexity of the observed stimulus-response patterns. PPT is largely grounded in autonomic measures, and current work is attempting to integrate electroencephalographic measures, particularly components in the event-related brain potentials reflecting aspects of stimulus processing. The emphasis in the current presentation is on the use of the defining criteria of the habituation phenomenon, and Groves and Thompson's Dual-process Theory, in the development of PPT.

Analysis of a filament stretching rheometer

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1996-01-01

A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown.......A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown....

EFFICACY OF MODIFIED PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING WITH CRYOTHERAPY OVER MANUAL PASSIVE STRETCHING WITH CRYOTHERAPY ON HAMSTRING FLEXIBILITY

Directory of Open Access Journals (Sweden)

Shamik Bhattacharjee

2016-04-01

Full Text Available Background: Healthy individuals, to ease and accomplish their activities of daily living they need flexible body without any tightness in the muscles, particularly those used for a definite function. Cooling soft tissues in a lengthened position after stretching has been shown to promote more lasting increases in soft tissue length and minimize post stretch muscle soreness. There are less documented studies which compared modified proprioceptive neuromuscular facilitation (PNF stretch over passive manual stretch with cold application commonly after the interventions. Methods: Thirty high school going healthy students were divided into two groups- Group I received Passive Manual stretching (n=15 and Group II received modified PNF stretching (n=15 and both groups received cold application after the interventions for 10 minutes commonly for 5 days. ROM was taken on day 1, day 5 and day 7. Results: After day 7, Group II with Modified PNF stretching along with cold application showed a significant increase in range of motion tested with active knee extension test (AKET. Conclusion: Modified PNF stretching is considered to be the effective intervention in increasing and maintaining ROM in AKET over passive manual stretching with cold applications commonly after the interventions.

A novel reflex cough testing device.

Science.gov (United States)

Fujiwara, Kazunori; Kawamoto, Katsuyuki; Shimizu, Yoko; Fukuhara, Takahiro; Koyama, Satoshi; Kataoka, Hideyuki; Kitano, Hiroya; Takeuchi, Hiromi

2017-01-18

The reflex cough test is useful for detecting silent aspiration, a risk factor for aspiration pneumonia. However, assessing the risk of aspiration pneumonia requires measuring not only the cough reflex but also cough strength. Currently, no reflex cough testing device is available that can directly measure reflex cough strength. We therefore developed a new testing device that can easily and simultaneously measure cough strength and the time until the cough reflex, and verified whether screening with this new instrument is feasible for evaluating the risk of aspiration pneumonia. This device consists of a special pipe with a double lumen, a nebulizer, and an electronic spirometer. We used a solution of prescription-grade L-tartaric acid to initiate the cough reflex. The solution was inhaled through a mouthpiece as a microaerosol produced by an ultrasonic nebulizer. The peak cough flow (PCF) of the induced cough was measured with the spirometer. The 70 patients who participated in this study comprised 49 patients without a history of pneumonia (group A), 21 patients with a history of pneumonia (group B), and 10 healthy volunteers (control group). With the novel device, PCF and time until cough reflex could be measured without adverse effects. The PCF values were 118.3 ± 64.0 L/min, 47.7 ± 38.5 L/min, and 254.9 ± 83.8 L/min in group A, group B, and the control group, respectively. The PCF of group B was significantly lower than that of group A and the control group (p reflex was 4.2 ± 5.9 s, 7.0 ± 7.0 s, and 1 s in group A, group B, and the control group, respectively. This duration was significantly longer for groups A and B than for the control group (A: p reflex and the strength of involuntary coughs for assessment of patients at risk of aspiration pneumonia.

Central sensitization in spinal cord injured humans assessed by reflex receptive fields

DEFF Research Database (Denmark)

Biurrun Manresa, José Alberto; Finnerup, Nanna Susanne Brix; Johannesen, Inger Lauge

2014-01-01

OBJECTIVE: To investigate the effects of central sensitization, elicited by intramuscular injection of capsaicin, by comparing the reflex receptive fields (RRF) of spinally-intact volunteers and spinal cord injured volunteers that present presensitized spinal nociceptive mechanisms. METHODS...... after an intramuscular injection of capsaicin in the foot sole in order to induce central sensitization. RESULTS: Both groups presented RRF expansion and lowered NWR thresholds immediately after capsaicin injection, reflected by the enlargement of RRF sensitivity areas and RRF probability areas....... Moreover, the topography of the RRF sensitivity and probability areas were significantly different in SCI volunteers compared to NI volunteers in terms of size and shape. CONCLUSIONS: SCI volunteers can develop central sensitization, despite adaptive/maladaptive changes in synaptic plasticity and lack...

Flexibility and stretching physiology : responses and adaptations to different stretching intensities.

OpenAIRE

Freitas, Sandro Remo Martins Neves Ramos

2014-01-01

Doutoramento em Motricidade Humana, especialidade de Biomecânica Research and reported literature regarding the conceptual, methodological, and training effects of stretching with different intensities are scarce. The purposes of this thesis were to: i) explore and develop methodological conditions to achieve the second purpose (studies: 1 to 3); ii) characterize the acute and chronic effects induced by different stretching intensities on skeletal muscle and joint mechanical properti...

"On Becoming a Critically Reflexive Practitioner" Redux: What Does It Mean to "Be" Reflexive?

Science.gov (United States)

Cunliffe, Ann L.

2016-01-01

In this commentary, Cunliffe states that is convinced that reflexivity offers a way of foregrounding our moral and ethical responsibility for people and for the world around us. To "BE" reflexive was defined as embracing "subjective understandings of reality as a basis for thinking more critically about the impact of our…

EFFECTIVENESS OF PNF STRETCHING AND CYCLIC STRETCHING OF CALF TIGHTNESS ON COLLEGE GOING GIRLS

Directory of Open Access Journals (Sweden)

Ashlesha Sirari

2015-06-01

Full Text Available Background: Flexibility helps with injury prevention, the reduction of soreness following a workout, and a general sense of well-being. There are different stretching techniques and protocols for improvements in calf extensibility and flexibility. The purpose of the study was to investigate the effectiveness of two techniques i.e. CYCLIC and PNF stretching which improves calf flexibility. This study was done to find the effectiveness of calf Cyclic and PNF stretching technique to improve calf flexibility. Methods: 30 subjects with age group 21-22 years were randomly allocated to 2 groups equally. Group 1(n=15 were given CYCLIC and group 2(n=15 were given PNF stretching technique. Plantar flexion was used to measure the calf tightness which was done before and after the treatment. Treatment was given for 7 days and on the 7th day the calf tightness was again measured. Results: The mean difference of the CYCLIC is 4.6 and mean difference of PNF is 4.7 which indicate that CYCLIC and PNF both are effective to improve calf flexibility but PNF is more effective than CYCLIC to improve calf flexibility. Conclusion: The neurophysiological basis of PNF, stating that the excitatory efficient of the neuromuscular spindle or the inhibitory afferent of the Golgi tendon organ (GTO or both are responsible for the effects. During PNF stretch and isometric contraction of stretched agonists for extended period may cause activation of its neuromuscular spindle. The increase in tension created during the isometric contraction of the pre – lengthened agonist contracts concentrically. Both the fascia & the spindle of the agonist adjust to the nearly lengthened position. These impulses travel via causing post synaptic inhibition of the motor neuron to agonist increasing the tension from the GTO. These impulses can override the impulses coming from the neuromuscular spindles arousing the muscle to reflexly resist to the change in length, thus helping in lengthening

AMPUTATION AND REFLEX SYMPATHETIC DYSTROPHY

NARCIS (Netherlands)

GEERTZEN, JHB; EISMA, WH

Reflex sympathetic dystrophy is a chronic pain syndrome characterized by chronic burning pain, restricted range of motion, oedema and vasolability. Patients are difficult to treat and the prognosis is very often poor. This report emphasizes that an amputation in case of a reflex sympathetic

Portraying Reflexivity in Health Services Research.

Science.gov (United States)

Rae, John; Green, Bill

2016-09-01

A model is proposed for supporting reflexivity in qualitative health research, informed by arguments from Bourdieu and Finlay. Bourdieu refers to mastering the subjective relation to the object at three levels-the overall social space, the field of specialists, and the scholastic universe. The model overlays Bourdieu's levels of objectivation with Finlay's three stages of research (pre-research, data collection, and data analysis). The intersections of these two ways of considering reflexivity, displayed as cells of a matrix, pose questions and offer prompts to productively challenge health researchers' reflexivity. Portraiture is used to show how these challenges and prompts can facilitate such reflexivity, as illustrated in a research project. © The Author(s) 2016.

The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects.

LENUS (Irish Health Repository)

O'Sullivan, Kieran

2009-01-01

BACKGROUND: Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. METHODS: A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. RESULTS: Across both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05). CONCLUSION: Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced

Too Busy for Reflexivity?

DEFF Research Database (Denmark)

Ratner, Helene

What Danish school managers can teach STS researchers about epistemological ideals and pragmatic morals. Reflexivity has an ambivalent status in both anthropology and Science and Technology Studies. On the one hand, the critique of representation at the heart of the reflexivity debates of the 1980s...... highlighted non-symmetric relationships between observer and observed and accused the academic text of enacting a realist genre, concealing the relativism entailed in textual production (Clifford and Marcus 1986, Woolgar 1988, Ashmore 1989). On the other hand, the reflexivity program produced fears...... of a “corrosive relativism in which everything is but a more or less clever expression of opinion” (Geertz 1988:2, 3) and it has suffered the little flattering accusations of piling "layer upon layer of self-consciousness to no avail" (Latour 1988:170) with little “interest [for] … theoretically ambitious...

The passive of reflexive verbs in Icelandic

Directory of Open Access Journals (Sweden)

Hlíf Árnadóttir

2011-10-01

Full Text Available The Reflexive Passive in Icelandic is reminiscent of the so-called New Passive (or New Impersonal in that the oblique case of a passivized object NP is preserved. As is shown by recent surveys, however, speakers who accept the Reflexive Passive do not necessarily accept the New Passive, whereas conversely, speakers who accept the New Passive do also accept the Reflexive Passive. Based on these results we suggest that there is a hierarchy in the acceptance of passive sentences in Icelandic, termed the Passive Acceptability Hierarchy. The validity of this hierarchy is confirmed by our diachronic corpus study of open access digital library texts from Icelandic journals and newspapers dating from the 19th and 20th centuries (tímarit.is. Finally, we sketch an analysis of the Reflexive Passive, proposing that the different acceptability rates of the Reflexive and New Passives lie in the argument status of the object. Simplex reflexive pronouns are semantically dependent on the verbs which select them, and should therefore be analyzed as syntactic arguments only, and not as semantic arguments of these verbs.

EFFECTIVENESS OF PNF STRETCHING VERSUS STATIC STRETCHING ON PAIN AND HAMSTRING FLEXIBILITY FOLLOWING MOIST HEAT IN INDIVIDUALS WITH KNEE OSTEOARTHRITIS

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Meena .V

2016-10-01

Full Text Available Background: Osteoarthritis (OA is a degenerative joint disease and one of the major public health problem that causesfunctional impairment and reduced quality of life. To compare the effectiveness of PNF Hold relax stretching versus Static stretching on pain and flexibility of hamstring following moist heat in individuals with knee osteoarthritis. Hamstring tightness is the major problem in knee osteoarthritis individuals. Therefore the need of study is comparing the effectiveness of PNF Hold relax stretching versus static stretching on pain and flexibility of hamstrings following moist heat in knee osteoarthritis participants. Determining the effects of PNF Hold relax stretching versus Static stretching along with moist heat on pain and hamstring flexibility by VAS and Active knee extension range of motion in knee osteoarthritis individuals. Methods: 30 subjects with symptoms of knee osteoarthritis were randomly distributed into 2 groups 15 in each group. PNF Hold relax stretching along with moist heat is compared to Static stretching along with moist heat. Pain was measured by Visual Analogue Scale (VAS and hamstring flexibility by Active knee Extension Range of Motion (AKEROM by universal goniometer. Measurements are taken pre and post intervention. Results: The results indicated PNF Hold relax stretching along with moist heat showed a statistically significant improvement in pain (p<0.05 and improvement in hamstring flexibility (p<0.05 when compared to Static stretching along with moist heat. Conclusion: Subjects with PNF Hold relax stretching along with moist heat showed significant improvement in pain reduction and improving hamstring flexibility than Static stretching along with moist heat.

Endovascular rescue method for undesirably stretched coil.

Science.gov (United States)

Cho, Jae Hoon

2014-10-01

Undesirable detachment or stretching of coils within the parent artery during aneurysm embolization can be related with thrombus formation, which can be caused occlusion of parent artery or embolic event(s). To escape from this situation, several rescue methods have been reported. A case with undesirably stretched coil in which another rescue method was used, is presented. When the stretched coil is still located in the coil delivery microcatheter, the stretched coil can be removed safely using a snare and a handmade monorail microcatheter. After a snare is lodged in the handmade monorail microcatheter, the snare is introduced over the coil delivery micorcatheter and located in the distal part of the stretched coil. After then, the handmade monorail microcatheter captures the stretched coil and the snare as one unit. This technique using a handmade monorail microcatheter and a snare can be a good rescue modality for the undesirably stretched coil, still remained within the coil delivery microcatheter.

Effects of cold-pressor and mental arithmetic on pupillary light reflex

International Nuclear Information System (INIS)

Davis, B C; Daluwatte, C; Colona, N C; Yao, D G

2013-01-01

Dynamic pupillary light reflex (PLR) is a simple neurological test that can be useful for assessment of autonomic disorders. In this study, we investigated the changes in PLR induced by mental arithmetic task and cold pressor trials which are often applied in research as model systems to elicit autonomic responses. PLR was recorded before, during and after mental arithmetic and cold pressor tasks in 20 healthy adults (ten males and ten females). Stress-induced sympathetic activation was evident as shown in the increased blood pressure during both tasks. Although the pupillary constriction amplitude did not show significant changes, both constriction time and redilation time changed during the tasks. A significant gender effect was observed in cold pressor that suggested more sympathetic activation in males and faster parasympathetic activation in females in response to light stimulation under cold pressor. (paper)

O conceito de reflexão de Hegel como crítica aos conceitos de essência e de reflexão tradicionais

Directory of Open Access Journals (Sweden)

Christian Iber

2017-02-01

Full Text Available O presente artigo ilumina o específico do conceito de reflexão de Hegel em cinco momentos. Em um primeiro momento, delineia-se um esboço do conceito de reflexão na lógica da essência de Hegel. Em um segundo momento, o conceito de reflexão de Hegel é apresentado como estrutura lógica objetiva em contraste com a reflexão subjetiva da consciência e do entendimento, com a qual, ao mesmo tempo, o conceito de essência ontológica independente da reflexão é submetido a uma crítica. Do novo conceito de reflexão de Hegel resulta, em terceiro lugar, uma adaptação radical do círculo vicioso na teoria tradicional da reflexão da autoconsciência. Num quarto momento, lança-se um olhar sobre o conceito de reflexão anterior de Hegel como pensar do entendimento que separa, do qual o conceito de reflexão posterior se distingue. Por fim, apresenta-se, em quinto lugar, a lógica da reflexão de Hegel como crítica à fundação ontológica da reflexão em Schelling. O conceito de reflexão de Hegel se mostra, com isto, como crítica da metafísica ontológica tradicional e como fundação de uma metafísica da relacionalidade absoluta que supera a relatividade do pensar moderno do entendimento.

Relationship between vomiting reflex during esophagogastroduodenoscopy and dyspepsia symptoms.

Science.gov (United States)

Enomoto, Shotaro; Watanabe, Mika; Yoshida, Takeichi; Mukoubayashi, Chizu; Moribata, Kosaku; Muraki, Yosuke; Shingaki, Naoki; Deguchi, Hisanobu; Ueda, Kazuki; Inoue, Izumi; Maekita, Takao; Iguchi, Mikitaka; Tamai, Hideyuki; Kato, Jun; Fujishiro, Mitsuhiro; Oka, Masashi; Mohara, Osamu; Ichinose, Masao

2012-09-01

Although frequent vomiting reflexes during esophagogastroduodenoscopy (EGD) causes suffering in patients, very few studies have investigated the characteristics of subjects who frequently develop vomiting reflexes. This study examined the incidence of the vomiting reflex and related factors, especially upper gastrointestinal symptoms, among individuals undergoing transoral EGD. Subjects included 488 consecutive adults (mean age, 56.1 ± 8.9 years) who underwent transoral EGD for gastric cancer screening between February 2010 and March 2011. All procedures were performed by an endoscopist with 15 years of experience. Based on a questionnaire survey using the frequency scale for the symptoms of gastroesophageal reflux disease (FSSG), symptoms (dyspepsia and acid reflux symptoms) and the number of vomiting reflexes during EGD were recorded. Of the 488 subjects, 271 (56%) developed vomiting reflexes (mean, 4.2 times). This reflex-positive group was younger (54.3 ± 9.5 years) than the reflex-negative group (58.3 ± 7.7 years, P reflex-positive group with a high FSSG dyspepsia score (2.27 ± 2.57 vs 1.23 ± 1.84; P acid reflux symptom score (1.96 ± 2.22 vs 1.34 ± 2.14; P reflex-negative group. Multivariate analysis also showed a significant correlation between these four factors and the occurrence of vomiting reflexes. Using an FSSG dyspepsia score of 1 as the cut-off offered 68% sensitivity and 57% specificity for predicting the occurrence of vomiting reflexes. Based on FSSG questionnaire responses on upper gastrointestinal symptoms, dyspepsia symptoms, in particular, are related to presence of vomiting reflexes during EGD. © 2012 The Authors. Digestive Endoscopy © 2012 Japan Gastroenterological Endoscopy Society.

Aging deteriorated perception of urge-to-cough without changing cough reflex threshold to citric acid in female never-smokers.

Science.gov (United States)

Ebihara, Satoru; Ebihara, Takae; Kanezaki, Masashi; Gui, Peijun; Yamasaki, Miyako; Arai, Hiroyuki; Kohzuki, Masahiro

2011-06-28

The effect of aging on the cognitive aspect of cough has not been studied yet. The purpose of this study is to investigate the aging effect on the perception of urge-to-cough in healthy individuals. Fourteen young, female, healthy never-smokers were recruited via public postings. Twelve elderly female healthy never-smokers were recruited from a nursing home residence. The cough reflex threshold and the urge-to-cough were evaluated by inhalation of citric acid. The cough reflex sensitivities were defined as the lowest concentration of citric acid that elicited two or more coughs (C2) and five or more coughs (C5). The urge-to-cough was evaluated using a modified the Borg scale. There was no significant difference in the cough reflex threshold to citric acid between young and elderly subjects. The urge-to-cough scores at the concentration of C2 and C5 were significantly smaller in the elderly than young subjects. The urge-to-cough log-log slope in elderly subjects (0.73 ± 0.71 point · L/g) was significantly gentler than those of young subjects (1.35 ± 0.53 point · L/g, p < 0.01). There were no significant differences in the urge-to-cough threshold estimated between young and elderly subjects. The cough reflex threshold did not differ between young and elderly subjects whereas cognition of urge-to-cough was significantly decreased in elderly subjects in female never-smokers. Objective monitoring of cough might be important in the elderly people.

The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects

Directory of Open Access Journals (Sweden)

Murray Elaine

2009-04-01

Full Text Available Abstract Background Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. Methods A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM. 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1 at baseline; (2 after warm-up; (3 after stretch (static or dynamic and (4 after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. Results Across both groups, there was a significant main effect for time (p 0.05. Using ANCOVA to adjust for the non-significant (p = 0.141 baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05. Conclusion Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes. Trial Registration ACTRN12608000638336

Indian red scorpion venom-induced augmentation of cardio-respiratory reflexes and pulmonary edema involve the release of histamine.

Science.gov (United States)

Dutta, Abhaya; Deshpande, Shripad B

2011-02-01

Pulmonary edema is a consistent feature of Mesobuthus tamulus (MBT) envenomation. Kinins, prostaglandins and other inflammatory mediators are implicated in it. Since, histamine also increases capillary permeability, this study was undertaken to evaluate whether MBT venom utilizes histamine to produce pulmonary edema and augmentation of cardio-respiratory reflexes evoked by phenylbiguanide (PBG). Blood pressure, respiratory excursions and ECG were recorded in urethane anaesthetized adult rats. Injection of PBG (10 μg/kg) produced apnoea, hypotension and bradycardia and the responses were augmented after exposure to venom (100 μg/kg). There was increased pulmonary water content in these animals. Pretreatment with pheniramine maleate (H₁ antagonist, 3 mg/kg) blocked both venom-induced augmentation of PBG response and pulmonary edema. In another series, compound 48/80 (mast cell depletor) was treated for 4 days then the PBG responses were elicited as before. At the end of the experiments, mast cells were counted from the peritoneal fluid. The venom-induced pulmonary edema and the augmentation of PBG reflex were not observed in compound 48/80 treated animals. Further, mast cells in the peritoneal fluid were absent in this group as compared to vehicle treated group (29 ± 7.9 cells/mm³). These observations indicate that venom-induced pulmonary edema and augmentation of PBG reflexe are mediated through mast cells by involving H₁ receptors. Copyright © 2010 Elsevier Ltd. All rights reserved.

A near catastrophe from trigeminocardiac reflex

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Parmod K Bithal

2017-01-01

Full Text Available Trigeminocardiac reflex is a brainstem reflex that results from stimulation of any branch of the trigeminal nerve along its course. It produces a constellation of signs and symptoms decrease in blood pressure (BP and heart rate, dysrhythmias, apnoea and increased gastric motility. We present a case of 80-year-old female patient who developed alarming hypotension and bradycardia during craniotomy for meningioma excision resulting from this reflex. In the face of refractory hypotension despite administering ephedrine and phenylephrine, we had to resort to adrenaline to restore her normal BP.

Dynamic Contractility and Efficiency Impairments in Stretch-Shortening Cycle Are Stretch-Load-Dependent After Training-Induced Muscle Damage

NARCIS (Netherlands)

Vaczi, Mark; Racz, Levente; Hortobagyi, Tibor; Tihanyi, Jozsef

Vaczi, M, Racz, L, Hortobagyi, T, and Tihanyi, J. Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load-dependent after training-induced muscle damage. J Strength Cond Res 27(8): 2171-2179, 2013To determine the acute task and stretch-load dependency of

Biaxial stretching of film principles and applications

CERN Document Server

Demeuse, M T

2011-01-01

Biaxial (having two axes) stretching of film is used for a range of applications and is the primary manufacturing process by which products are produced for the food packaging industry. Biaxial stretching of film: principles and applications provides an overview of the manufacturing processes and range of applications for biaxially stretched films. Part one reviews the fundamental principles of biaxial stretching. After an introductory chapter which defines terms, chapters discuss equipment design and requirements, laboratory evaluations, biaxial film structures and typical industrial processes for the biaxial orientation of films. Additional topics include post production processing of biaxially stretched films, the stress-strain behaviour of poly(ethylene terephthalate) and academic investigations of biaxially stretched films. Part two investigates the applications of biaxial films including fresh cut produce, snack packaging and product labelling. A final chapter investigates potential future trends for bi...

The vestibular implant: Frequency-dependency of the electrically evoked Vestibulo-Ocular Reflex in humans

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Raymond eVan De Berg

2015-01-01

Full Text Available The Vestibulo-Ocular Reflex (VOR shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR elicited by a vestibular implant, showed the same frequency-dependency.Twelve vestibular electrodes implanted in 7 patients with bilateral vestibular hypofunction were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5Hz, 1Hz, and 2Hz. The main characteristics of the eVOR were evaluated and compared to the natural VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies.A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the natural VOR. Other characteristics of the (eVOR (angle, habituation-index, and asymmetry showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the normal vestibular system.

Attentional modulation of reflex cough.

Science.gov (United States)

Janssens, Thomas; Silva, Mitchell; Davenport, Paul W; Van Diest, Ilse; Dupont, Lieven J; Van den Bergh, Omer

2014-07-01

Reflex cough is a defensive response generated in the brainstem in response to chemical and mechanical stimulation of the airways. However, converging evidence shows that reflex cough is also influenced by central neural control processes. In this study, we investigate whether reflex cough can be modulated by attentional focus on either external stimuli or internal cough-related stimuli. Healthy volunteers (N = 24; seven men; age range, 18-25 years) completed four blocks of citric acid-induced cough challenges while, simultaneously, auditory stimuli were presented. Within each block, four concentrations were administered (30, 100, 300 and 1,000 mM, randomized). During two subsequent blocks, participants focused their attention externally (counting tones). During the other two blocks, participants focused their attention internally (counting coughs). The order of attentional focus was counterbalanced across participants. Ratings of the urge to cough were collected after each challenge. Cough frequency was determined by audio recording. Cough frequency was higher when participants focused their attention internally vs externally (P Reflex cough can be modulated by attentional focus. Internally focused attention may be a mechanism involved in excessive (idiopathic) cough, while an external focus may be introduced as part of treatments targeting excessive cough.

Correlation between structure and conductivity in stretched Nafion

Science.gov (United States)

Allahyarov, Elshad; Taylor, Philip

2008-03-01

We have used coarse-grained simulation methods to investigate the effect of stretching-induced structure orientation on the proton conductivity of Nafion-like polyelectrolyte membranes. Recent experimental data on the morphology of ionomers describe Nafion as an aggregation of polymeric backbone chains forming elongated objects embedded in a continuous ionic medium. Uniaxial stretching of a recast Nafion film causes a preferential orientation of these objects in the direction of stretching. Our simulations of humid Nafion show that this has a strong effect on the proton conductivity, which is enhanced along the stretching direction, while the conductivity perpendicular to the stretched polymer backbone is strongly reduced. Stretching also causes the perfluorinated side chains to orient perpendicular to the stretching axis. The sulphonate multiplets shrink in diameter as the stretching is increased and show a spatially periodic ordering in their distribution. This in turn affects the distribution of contained water at low water contents. The water forms a continuous network with narrow bridges between small water clusters absorbed in head-group multiplets. We find the morphological changes in the stretched Nafion to be retained upon removal of the uniaxial stress.

Characterization of mechanical behavior of a porcine pulmonary artery strip using a randomized uniaxial stretch and stretch-rate protocol

Directory of Open Access Journals (Sweden)

Criscione John C

2008-01-01

Full Text Available Abstract Background Much of the experimental work in soft tissue mechanics has been focused on fitting approximate relations for specific tissue types from aggregate data on multiple samples of the tissue. Such relations are needed for modeling applications and have reasonable predictability – especially given the natural variance in specimens. There is, however, much theoretical and experimental work to be done in determining constitutive behaviors for particular specimens and tissues. In so doing, it may be possible to exploit the natural variation in tissue ultrastructure – so to relate ultrastructure composition to tissue behavior. Thus, this study focuses on an experimental method for determining constitutive behaviors and illustrates the method with analysis of a porcine pulmonary artery strip. The method characterizes the elastic part of the response (implicitly in terms of stretch and the inelastic part in terms of short term stretch history (i.e., stretch-rate Ht2, longer term stretch history Ht1, and time since the start of testing T. Methods A uniaxial testing protocol with a random stretch and random stretch-rate was developed. The average stress at a particular stretch was chosen as the hyperelastic stress response, and deviation from the mean at this particular stretch is chosen as the inelastic deviation. Multivariable Linear Regression Analysis (MLRA was utilized to verify if Ht2, Ht1, and T are important factors for characterizing the inelastic deviation. For acquiring Ht2 and Ht1, an integral function type of stretch history was employed with time constants chosen from the relaxation spectrum of an identical size strip from the same tissue with the same orientation. Finally, statistical models that characterize the inelasticity were developed at various, nominal values of stretch, and their predictive capability was examined. Results Inelastic deviation from hyperelasticity was high (31% for low stretch and declined

Motivational priming and processing interrupt: startle reflex modulation during shallow and deep processing of emotional words.

Science.gov (United States)

Herbert, Cornelia; Kissler, Johanna

2010-05-01

Valence-driven modulation of the startle reflex, that is larger eyeblinks during viewing of unpleasant pictures and inhibited blinks while viewing pleasant pictures, is well documented. The current study investigated, whether this motivational priming pattern also occurs during processing of unpleasant and pleasant words, and to what extent it is influenced by shallow vs. deep encoding of verbal stimuli. Emotional and neutral adjectives were presented for 5s, and the acoustically elicited startle eyeblink response was measured while subjects memorized the words by means of shallow or deep processing strategies. Results showed blink potentiation to unpleasant and blink inhibition to pleasant adjectives in subjects using shallow encoding strategies. In subjects using deep-encoding strategies, blinks were larger for pleasant than unpleasant or neutral adjectives. In line with this, free recall of pleasant words was also better in subjects who engaged in deep processing. The results suggest that motivational priming holds as long as processing is perceptual. However, during deep processing the startle reflex appears to represent a measure of "processing interrupt", facilitating blinks to those stimuli that are more deeply encoded. Copyright 2010 Elsevier B.V. All rights reserved.

Wh-filler-gap dependency formation guides reflexive antecedent search

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Michael eFrazier

2015-10-01

Full Text Available Prior studies on online sentence processing have shown that the parser can resolve non-local dependencies rapidly and accurately. This study investigates the interaction between the processing of two such non-local dependencies: wh-filler-gap dependencies (WhFGD and reflexive-antecedent dependencies. We show that reflexive-antecedent dependency resolution is sensitive to the presence of a WhFGD, and argue that the filler-gap dependency established by WhFGD resolution is selected online as the antecedent of a reflexive dependency. We investigate the processing of constructions like (1, where two NPs might be possible antecedents for the reflexive, namely which cowgirl and Mary. Even though Mary is linearly closer to the reflexive, the only grammatically licit antecedent for the reflexive is the more distant wh-NP, which cowgirl. 1. Which cowgirl did Mary expect to have injured herself due to negligence?Four eye-tracking text-reading experiments were conducted on examples like (1, differing in whether the embedded clause was non-finite (1 and 3 or finite (2 and 4, and in whether the tail of the wh-dependency intervened between the reflexive and its closest overt antecedent (1 and 2 or the wh-dependency was associated with a position earlier in the sentence (3 and 4.The results of Experiments 1 and 2 indicate the parser accesses the result of WhFGD formation during reflexive antecedent search. The resolution of a wh-dependency alters the representation that reflexive antecedent search operates over, allowing the grammatical but linearly distant antecedent to be accessed rapidly. In the absence of a long-distance WhFGD (Exp. 3 and 4, wh-NPs were not found to impact reading times of the reflexive, indicating that the parser's ability to select distant wh-NPs as reflexive antecedents crucially involves syntactic structure.

Reflexivity and social justice

DEFF Research Database (Denmark)

Maksimovic, Tijana; Jakobsen, Helle Nordentoft

2017-01-01

Career practitioners’ reflexive understanding of their professional role as change agents in career guidance and counselling practices has a major impact on how social justice can be achieved. This entitles an awareness of the way in which guidance and counselling practices are embedded in the co......Career practitioners’ reflexive understanding of their professional role as change agents in career guidance and counselling practices has a major impact on how social justice can be achieved. This entitles an awareness of the way in which guidance and counselling practices are embedded...

Stretched polygons in a lattice tube

Energy Technology Data Exchange (ETDEWEB)

Atapour, M [Department of Mathematics and Statistics, York University, Toronto, ON M3J 1P3 (Canada); Soteros, C E [Department of Mathematics and Statistics, University of Saskatchewan, Saskatoon, SK S7N 5E6 (Canada); Whittington, S G [Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6 (Canada)], E-mail: atapour@mathstat.yorku.ca, E-mail: soteros@math.usask.ca, E-mail: swhittin@chem.utoronto.ca

2009-08-14

We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n {yields} {infinity}. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n {yields} {infinity}. Thus as n {yields} {infinity} when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

Stretched polygons in a lattice tube

International Nuclear Information System (INIS)

Atapour, M; Soteros, C E; Whittington, S G

2009-01-01

We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n → ∞. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n → ∞. Thus as n → ∞ when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

Botulinum Neurotoxin A Injections Influence Stretching of the Gastrocnemius Muscle-Tendon Unit in an Animal Model

Directory of Open Access Journals (Sweden)

Christopher J. Tuohy

2012-08-01

Full Text Available Botulinum Neurotoxin A (BoNT-A injections have been used for the treatment of muscle contractures and spasticity. This study assessed the influence of (BoNT-A injections on passive biomechanical properties of the muscle-tendon unit. Mouse gastrocnemius muscle (GC was injected with BoNT-A (n = 18 or normal saline (n = 18 and passive, non-destructive, in vivo load relaxation experimentation was performed to examine how the muscle-tendon unit behaves after chemical denervation with BoNT-A. Injection of BoNT-A impaired passive muscle recovery (15% vs. 35% recovery to pre-stretching baseline, p < 0.05 and decreased GC stiffness (0.531 ± 0.061 N/mm vs. 0.780 ± 0.037 N/mm, p < 0.05 compared to saline controls. The successful use of BoNT-A injections as an adjunct to physical therapy may be in part attributed to the disruption of the stretch reflex; thereby modulating in vivo passive muscle properties. However, it is also possible that BoNT-A injection may alter the structure of skeletal muscle; thus modulating the in vivo passive biomechanical properties of the muscle-tendon unit.

O conceito de reflexão de Hegel como crítica aos conceitos de essência e de reflexão tradicionais

OpenAIRE

Christian Iber

2017-01-01

O presente artigo ilumina o específico do conceito de reflexão de Hegel em cinco momentos. Em um primeiro momento, delineia-se um esboço do conceito de reflexão na lógica da essência de Hegel. Em um segundo momento, o conceito de reflexão de Hegel é apresentado como estrutura lógica objetiva em contraste com a reflexão subjetiva da consciência e do entendimento, com a qual, ao mesmo tempo, o conceito de essência ontológica independente da reflexão é submetido a uma crítica. Do novo conceito d...

Stretch Marks

Science.gov (United States)

... completely without the help of a dermatologist or plastic surgeon. These doctors may use one of many types of treatments — from actual surgery to techniques like microdermabrasion and laser treatment — to reduce the appearance of stretch marks. These techniques are ...

[Effects of morphine on pupillary light reflex in monkeys].

Science.gov (United States)

Meng, Zhi-Qiang; Zhang, Yu-Hua; Chen, Nan-Hui; Miao, Ying-Da; Hu, Xin-Tian; Ma, Yuan-Ye

2010-06-01

The pupil size of both human and other animals can be affected by light. Many kinds of psychiatrical and psychological disorders, such as drug abuse, associate with abnormal properties of pupillary light reflex. Thus, the properties of pupillary light reflex could serve as an indicator for drug abuse detection. However, the effect of drug abuse on pupillary light reflex is till unclear. To assess the effects of addictive drugs on pupillary light reflex quantificationally, in the present study, we examined the effects of morphine on pupil diameter and pupillary light reflex in rhesus monkeys. By measuring the pupil diameter at different timing points before and after the administration of morphine, we found that morphine administration reduced the diameter of pupil and decreased the constriction rate. Our present results provide an experimental support for applying the properties of pupillary light reflex as a reference in addicts' detection.

Effect of sildenafil (Viagra® on the genital reflexes of paradoxical sleep-deprived male rats

Directory of Open Access Journals (Sweden)

M.L. Andersen

2007-11-01

Full Text Available Since there is evidence that paradoxical sleep deprivation (PSD elicits penile erection (PE and ejaculation (EJ, and that the erectile response of rats is mediated by nitric oxide, the present study sought to extend the latter finding by assessing the effects of sildenafil on the genital reflexes of male Wistar rats subjected to PSD. We also determined the influence of sildenafil on hormone concentrations. In the first experiment, sildenafil at doses ranging from 0.08 to 0.32 mg/kg was administered intraperitoneally to rats that had been deprived of sleep for 4 days and to home cage controls (N = 8-10/group. The frequency of PE and EJ was measured for 60 min. PSD alone induced PE in 50% of the animals; however, a single injection of sildenafil did not significantly increase the percentage of rats displaying PE compared to PSD-saline or to home cage groups. PSD alone also induced spontaneous EJ, but this response was not potentiated by sildenafil in the dose range tested. Testosterone concentrations were significantly lower in PSD rats (137 ± 22 ng/dL than in controls (365 ± 38 ng/dL, whereas progesterone (0.9 ± 0.1 vs 5.4 ± 1 ng/mL and plasma dopamine (103.4 ± 30 vs 262.6 ± 77 pg/mL increased. These changes did not occur after sildenafil treatment. The data show that although sildenafil did not alter the frequency of genital reflexes, it antagonized hormonal (testosterone and progesterone and plasma dopamine changes induced by PSD. The stimulation of the genital reflexes by sildenafil did not result in potentiating effects in PSD rats.

Using ESO Reflex with Web Services

Science.gov (United States)

Järveläinen, P.; Savolainen, V.; Oittinen, T.; Maisala, S.; Ullgrén, M. Hook, R.

2008-08-01

ESO Reflex is a prototype graphical workflow system, based on Taverna, and primarily intended to be a flexible way of running ESO data reduction recipes along with other legacy applications and user-written tools. ESO Reflex can also readily use the Taverna Web Services features that are based on the Apache Axis SOAP implementation. Taverna is a general purpose Web Service client, and requires no programming to use such services. However, Taverna also has some restrictions: for example, no numerical types such integers. In addition the preferred binding style is document/literal wrapped, but most astronomical services publish the Axis default WSDL using RPC/encoded style. Despite these minor limitations we have created simple but very promising test VO workflow using the Sesame name resolver service at CDS Strasbourg, the Hubble SIAP server at the Multi-Mission Archive at Space Telescope (MAST) and the WESIX image cataloging and catalogue cross-referencing service at the University of Pittsburgh. ESO Reflex can also pass files and URIs via the PLASTIC protocol to visualisation tools and has its own viewer for VOTables. We picked these three Web Services to try to set up a realistic and useful ESO Reflex workflow. They also demonstrate ESO Reflex abilities to use many kind of Web Services because each of them requires a different interface. We describe each of these services in turn and comment on how it was used

Prevalence of family history in patients with reflex syncope

DEFF Research Database (Denmark)

Holmegard, Haya N; Benn, Marianne; Kaijer, Michelle Nymann

2013-01-01

Reflex syncope is defined by a rapid transient loss of consciousness caused by global cerebral hypoperfusion resulting from vasodilatation and/or bradycardia attributable to inappropriate cardiovascular reflexes. A hereditary component has been suggested, but prevalence of family history may differ...... among subtypes of reflex syncope, as these have different autonomic responses and pathogeneses may be diverse. The present study aimed to assess the prevalence of a positive family history of syncope and cardiovascular characteristics in patients with cardioinhibitory and vasodepressor reflex syncope....... Patients (n=74) were classified into subtypes of reflex syncope - cardioinhibition/asystole (Vasovagal Syncope International Study subtypes II-B [VASIS II-B], n=38) or vasodepressor (VASIS III, n=36) - using the head-up tilt test. Family history was obtained by questionnaires supplemented by interview...

Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

DEFF Research Database (Denmark)

Balle, S S; Magnusson, S P; McHugh, M P

2015-01-01

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength wa...

(Re)constructing Reflexivity: A Relational Constructionist Approach

NARCIS (Netherlands)

Hosking, D.M.; Pluut, B.

2010-01-01

This article distinguishes three discourses of reflexivity in relation to human inquiry. One of these arises from a post-modern, relational constructionist perspective which radically re-conceptualizes reflexivity: (a) as a local and co-constructed process oriented towards the question (b) how are

Ultimate concerns in late modernity: Archer, Bourdieu and reflexivity.

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Farrugia, David; Woodman, Dan

2015-12-01

Through a critique of Margaret Archer's theory of reflexivity, this paper explores the theoretical contribution of a Bourdieusian sociology of the subject for understanding social change. Archer's theory of reflexivity holds that conscious 'internal conversations' are the motor of society, central both to human subjectivity and to the 'reflexive imperative' of late modernity. This is established through critiques of Bourdieu, who is held to erase creativity and meaningful personal investments from subjectivity, and late modernity is depicted as a time when a 'situational logic of opportunity' renders embodied dispositions and the reproduction of symbolic advantages obsolete. Maintaining Archer's focus on 'ultimate concerns' in a context of social change, this paper argues that her theory of reflexivity is established through a narrow misreading and rejection of Bourdieu's work, which ultimately creates problems for her own approach. Archer's rejection of any pre-reflexive dimensions to subjectivity and social action leaves her unable to sociologically explain the genesis of 'ultimate concerns', and creates an empirically dubious narrative of the consequences of social change. Through a focus on Archer's concept of 'fractured reflexivity', the paper explores the theoretical necessity of habitus and illusio for understanding the social changes that Archer is grappling with. In late modernity, reflexivity is valorized just as the conditions for its successful operation are increasingly foreclosed, creating 'fractured reflexivity' emblematic of the complex contemporary interaction between habitus, illusio, and accelerating social change. © London School of Economics and Political Science 2015.

Reflexive Aero Structures for Enhanced Survivability, Phase I

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National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) proposes to develop an advanced reflexive structure system to increase the survivability of aerostructures. This reflexive...

Anticausatives are weak scalar expressions, not reflexive expressions

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Florian Schäfer

2016-07-01

Full Text Available We discuss conceptual and empirical arguments from Germanic, Romance and Slavic languages against an analysis treating anticausative verbs as derived from their lexical causative counterparts under reflexivization. Instead, we defend the standard account to the semantics of the causative alternation according to which anticausatives in general, and anticausatives marked with reflexive morphology in particular, denote simple one-place inchoative events that are logically entailed by their lexical causative counterparts. Under such an account, anticausative verbs are weak scalar expressions that stand in a semantico-pragmatic opposition to their strong lexical causative counterparts. Due to this scalar relation, the use of an anticausative can trigger the implicature that the use of its lexical causative counterpart is too strong. As usual with implicatures, they can be ‘metalinguistically’ denied, cancelled, or reinforced and we argue that these mechanisms explain all central empirical facts brought up in the literature in favor of a treatment of anticausatives as semantically reflexive predicates. Our results reinforce the view that the reflexive morphemes used in many (Indo-European languages to mark anticausatives do not necessarily trigger reflexive semantics. However, we also show that a string involving a reflexively marked (anti-causative verb can be forced into a semantically reflexive construal under particular conceptual or grammatical circumstances.

Organization of sensory input to the nociceptive-specific cutaneous trunk muscle reflex in rat, an effective experimental system for examining nociception and plasticity

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Petruska, Jeffrey C.; Barker, Darrell F.; Garraway, Sandra M.; Trainer, Robert; Fransen, James W.; Seidman, Peggy A.; Soto, Roy G.; Mendell, Lorne M.; Johnson, Richard D.

2013-01-01

Detailed characterization of neural circuitries furthers our understanding of how nervous systems perform specific functions and enables the use of those systems to test hypotheses. We have characterized the sensory input to the cutaneous trunk muscle (CTM; also cutaneus trunci (rat) or cutaneus maximus (mouse)) reflex (CTMR), which manifests as a puckering of the dorsal thoracolumbar skin and is selectively driven by noxious stimuli. CTM electromyography (EMG) and neurogram recordings in naïve rats revealed that CTMR responses were elicited by natural stimuli and electrical stimulation of all segments from C4 to L6, a much greater extent of segmental drive to the CTMR than previously described. Stimulation of some subcutaneous paraspinal tissue can also elicit this reflex. Using a selective neurotoxin, we also demonstrate differential drive of the CTMR by trkA-expressing and non-expressing small diameter afferents. These observations highlight aspects of the organization of the CTMR system which make it attractive for studies of nociception and anesthesiology and plasticity of primary afferents, motoneurons, and the propriospinal system. We use the CTMR system to qualitatively and quantitatively demonstrate that experimental pharmacological treatments can be compared to controls applied either to the contralateral side or to another segment, with the remaining segments providing controls for systemic or other treatment effects. These data indicate the potential for using the CTMR system as both an invasive and non-invasive quantitative assessment tool providing improved statistical power and reduced animal use. PMID:23983104

Electrocorticographic activity over sensorimotor cortex and motor function in awake behaving rats.

Science.gov (United States)

Boulay, Chadwick B; Chen, Xiang Yang; Wolpaw, Jonathan R

2015-04-01

Sensorimotor cortex exerts both short-term and long-term control over the spinal reflex pathways that serve motor behaviors. Better understanding of this control could offer new possibilities for restoring function after central nervous system trauma or disease. We examined the impact of ongoing sensorimotor cortex (SMC) activity on the largely monosynaptic pathway of the H-reflex, the electrical analog of the spinal stretch reflex. In 41 awake adult rats, we measured soleus electromyographic (EMG) activity, the soleus H-reflex, and electrocorticographic activity over the contralateral SMC while rats were producing steady-state soleus EMG activity. Principal component analysis of electrocorticographic frequency spectra before H-reflex elicitation consistently revealed three frequency bands: μβ (5-30 Hz), low γ (γ1; 40-85 Hz), and high γ (γ2; 100-200 Hz). Ongoing (i.e., background) soleus EMG amplitude correlated negatively with μβ power and positively with γ1 power. In contrast, H-reflex size correlated positively with μβ power and negatively with γ1 power, but only when background soleus EMG amplitude was included in the linear model. These results support the hypothesis that increased SMC activation (indicated by decrease in μβ power and/or increase in γ1 power) simultaneously potentiates the H-reflex by exciting spinal motoneurons and suppresses it by decreasing the efficacy of the afferent input. They may help guide the development of new rehabilitation methods and of brain-computer interfaces that use SMC activity as a substitute for lost or impaired motor outputs. Copyright © 2015 the American Physiological Society.

Reflexive Planning as Design and Work

DEFF Research Database (Denmark)

Lissandrello, Enza; Grin, John

2011-01-01

in planning emerges as a new tool for generating critical knowledge and dialogue that can synthesise the perspectives of multiple actors in a common understanding, existing structural constraints and a collective imagination of alternative future possibilities. Such research highlights the potential......In recent years, planning theorists have advanced various interpretations of the notion of reflexivity, inspired by American pragmatism, complexity theory, hermeneutics, discursive and collaborative planning. Scholars agree that “reflexivity” has a strong temporal dimension: it not only aims...... to solve present planning problems, but to imagine and understand alternative trajectories for future action. This article explores the practical utility of reflexivity for planners, through a case study that focuses on a project to promote sustainable development in the Port of Amsterdam. Reflexivity...

Enhanced startle reflexivity during presentation of visual nurture cues in young adults who experienced parental divorce in early childhood.

Science.gov (United States)

Hengesch, Xenia; Larra, Mauro F; Finke, Johannes B; Blumenthal, Terry D; Schächinger, Hartmut

2017-10-01

Adverse childhood experiences (ACE) may influence stress and affective processing in adulthood. Animal and human studies show enhanced startle reflexivity in adult participants with ACE. This study examined the impact of one of the most common ACE, parental divorce, on startle reflexivity in adulthood. Affective modulation of acoustically-elicited startle eye blink was assessed in a group of 23 young adults with self-reported history of parental divorce, compared to an age- and sex-matched control group (n=18). Foreground pictures were either aversive (e.g. mutilation and injury), standard appetitive (e.g. erotic, recreational sport), or nurture pictures (e.g. related to early life, parental care), intermixed with neutral pictures (e.g. household objects), and organized in three valence blocks delivered in a balanced, pseudo-randomized sequence. During picture viewing startle eye blinks were elicited by binaural white noise bursts (50ms, 105 dB) via headphones and recorded at the left orbicularis oculi muscle via EMG. A significant interaction of group×picture valence (p=0.01) was observed. Contrast with controls revealed blunted startle responsiveness of the ACE group during presentation of aversive pictures, but enhanced startle during presentation of nurture-related pictures. No group differences were found during presentation of standard appetitive pictures. ACE participants rated nurture pictures as more arousing (p=0.02) than did control participants. Results suggest that divorce in childhood led to altered affective context information processing in early adulthood. When exposed to unpleasant (vs. neutral) pictures participants with ACE showed less startle potentiation than controls. Nurture context, however, potentiated startle in ACE participants, suggesting visual cuing to activate protective behavioral responses. Copyright © 2017 Elsevier B.V. All rights reserved.

A discrete electromechanical model for human cardiac tissue: effects of stretch-activated currents and stretch conditions on restitution properties and spiral wave dynamics.

Science.gov (United States)

Weise, Louis D; Panfilov, Alexander V

2013-01-01

We introduce an electromechanical model for human cardiac tissue which couples a biophysical model of cardiac excitation (Tusscher, Noble, Noble, Panfilov, 2006) and tension development (adjusted Niederer, Hunter, Smith, 2006 model) with a discrete elastic mass-lattice model. The equations for the excitation processes are solved with a finite difference approach, and the equations of the mass-lattice model are solved using Verlet integration. This allows the coupled problem to be solved with high numerical resolution. Passive mechanical properties of the mass-lattice model are described by a generalized Hooke's law for finite deformations (Seth material). Active mechanical contraction is initiated by changes of the intracellular calcium concentration, which is a variable of the electrical model. Mechanical deformation feeds back on the electrophysiology via stretch-activated ion channels whose conductivity is controlled by the local stretch of the medium. We apply the model to study how stretch-activated currents affect the action potential shape, restitution properties, and dynamics of spiral waves, under constant stretch, and dynamic stretch caused by active mechanical contraction. We find that stretch conditions substantially affect these properties via stretch-activated currents. In constantly stretched medium, we observe a substantial decrease in conduction velocity, and an increase of action potential duration; whereas, with dynamic stretch, action potential duration is increased only slightly, and the conduction velocity restitution curve becomes biphasic. Moreover, in constantly stretched medium, we find an increase of the core size and period of a spiral wave, but no change in rotation dynamics; in contrast, in the dynamically stretching medium, we observe spiral drift. Our results may be important to understand how altered stretch conditions affect the heart's functioning.

A discrete electromechanical model for human cardiac tissue: effects of stretch-activated currents and stretch conditions on restitution properties and spiral wave dynamics.

Directory of Open Access Journals (Sweden)

Louis D Weise

Full Text Available We introduce an electromechanical model for human cardiac tissue which couples a biophysical model of cardiac excitation (Tusscher, Noble, Noble, Panfilov, 2006 and tension development (adjusted Niederer, Hunter, Smith, 2006 model with a discrete elastic mass-lattice model. The equations for the excitation processes are solved with a finite difference approach, and the equations of the mass-lattice model are solved using Verlet integration. This allows the coupled problem to be solved with high numerical resolution. Passive mechanical properties of the mass-lattice model are described by a generalized Hooke's law for finite deformations (Seth material. Active mechanical contraction is initiated by changes of the intracellular calcium concentration, which is a variable of the electrical model. Mechanical deformation feeds back on the electrophysiology via stretch-activated ion channels whose conductivity is controlled by the local stretch of the medium. We apply the model to study how stretch-activated currents affect the action potential shape, restitution properties, and dynamics of spiral waves, under constant stretch, and dynamic stretch caused by active mechanical contraction. We find that stretch conditions substantially affect these properties via stretch-activated currents. In constantly stretched medium, we observe a substantial decrease in conduction velocity, and an increase of action potential duration; whereas, with dynamic stretch, action potential duration is increased only slightly, and the conduction velocity restitution curve becomes biphasic. Moreover, in constantly stretched medium, we find an increase of the core size and period of a spiral wave, but no change in rotation dynamics; in contrast, in the dynamically stretching medium, we observe spiral drift. Our results may be important to understand how altered stretch conditions affect the heart's functioning.

Stretching and jamming of finite automata

NARCIS (Netherlands)

Beijer, de N.; Kourie, D.G.; Watson, B.W.; Cleophas, L.G.W.A.; Watson, B.W.

2004-01-01

In this paper we present two transformations on automata, called stretching and jamming. These transformations will, under certain conditions, reduce the size of the transition table, and under other conditions reduce the string processing time. Given a finite automaton, we can stretch it by

Voluntary Control of the Near Reflex: A Case Report

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Serpil Akar

2014-03-01

Full Text Available Spasm of the near reflex is a rare disorder that involves intermittent and variable episodes of esotropia, pseudomyopia, and pupillary myosis. It is usually functional in origin and is seen mainly in young patients. Treatment options for spasm of the near reflex have had variable success. In instances where the etiology of spasm of the near reflex was suspected to be hysteria, psychotherapy has proven beneficial. We report the case of an 11-year-old girl who had functional spasm of the near reflex. The symptoms persisted for two years. Symptomatic relief was achieved by cycloplegia and spectacle correction (added plus lenses at near. The patient also underwent psychological counseling. In our case, the functional spasm of the near reflex spontaneously resolved after 2 years. (Turk J Ophthalmol 2014; 44: 161-3

Magnitude and duration of stretch modulate fibroblast remodeling.

Science.gov (United States)

Balestrini, Jenna L; Billiar, Kristen L

2009-05-01

Mechanical cues modulate fibroblast tractional forces and remodeling of extracellular matrix in healthy tissue, healing wounds, and engineered matrices. The goal of the present study is to establish dose-response relationships between stretch parameters (magnitude and duration per day) and matrix remodeling metrics (compaction, strength, extensibility, collagen content, contraction, and cellularity). Cyclic equibiaxial stretch of 2-16% was applied to fibroblast-populated fibrin gels for either 6 h or 24 h/day for 8 days. Trends in matrix remodeling metrics as a function of stretch magnitude and duration were analyzed using regression analysis. The compaction and ultimate tensile strength of the tissues increased in a dose-dependent manner with increasing stretch magnitude, yet remained unaffected by the duration in which they were cycled (6 h/day versus 24 h/day). Collagen density increased exponentially as a function of both the magnitude and duration of stretch, with samples stretched for the reduced duration per day having the highest levels of collagen accumulation. Cell number and failure tension were also dependent on both the magnitude and duration of stretch, although stretch-induced increases in these metrics were only present in the samples loaded for 6 h/day. Our results indicate that both the magnitude and the duration per day of stretch are critical parameters in modulating fibroblast remodeling of the extracellular matrix, and that these two factors regulate different aspects of this remodeling. These findings move us one step closer to fully characterizing culture conditions for tissue equivalents, developing improved wound healing treatments and understanding tissue responses to changes in mechanical environments during growth, repair, and disease states.

21 CFR 890.1450 - Powered reflex hammer.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... hammer. (a) Identification. A powered reflex hammer is a motorized device intended for medical purposes...

Effects of postural changes of the upper limb on reflex transmission in the lower limb. Cervicolumbar reflex interactions in man.

Science.gov (United States)

Delwaide, P J; Figiel, C; Richelle, C

1977-06-01

The influence of passive changes in upper limb position on the excitability of three myotatic arc reflexes (soleus, quadriceps, and biceps femoris) of the lower limb has been explored on 42 volunteers. The results indicate that the excitability of the three myotatic arcs can be influenced at a distance by postural modifications of the upper limb. When the ipsilateral upper limb is forwards or the contralateral backwards, a facilitation of both soleus and quadriceps tendon reflexes is observed while the biceps femoris reflexes are reduced. This pattern of facilitation and inhibition is reversed when the ipsilateral upper limb is backwards or the contralateral forwards. The facilitations as well as inhibitions of proximal myotatic arc reflexes are quantitatively more marked than that of the soleus reflex. Facilitation and inhibition are not linearly related to the angle of the arm with the trunk. Effects begin at a considerable angle, become maximal at 45 degrees, and progressively disappear for greater values. It is suggested that the distinct pattern of facilitation and inhibition which is exerted in reciprocal fashion on extensor and flexor motor nuclei might depend on the long propriospinal neurones connecting cervical and lumbar enlargements.

Foam topology. Bending versus stretching dominated architectures

International Nuclear Information System (INIS)

Deshpande, V.; Ashby, M.; Fleck, N.

2000-01-01

Cellular solids can deform by either the bending or stretching of the cell walls. While most cellular solids are bending-dominated, those that are stretching-dominated are much more weight-efficient for structural applications. In this study we have investigated the topological criteria that dictate the deformation mechanism of a cellular solid by analysing the rigidity (or otherwise) of pin-jointed frameworks comprising inextensional struts. We show that the minimum node connectivity for a special class of lattice structured materials to be stretching-dominated is 6 for 2D foams and 12 for 3D foams. Similarly, sandwich plates comprising of truss cores faced with planar trusses require a minimum node connectivity of 9 to undergo stretching-dominated deformation for all loading states. (author)

Outside home. Notes on reflexivity

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Mara Clemente

2017-01-01

The paper proffers the idea in which a “reflexive process” on subjectivity can involve and/or hopefully involve the entire experience of the researcher, going beyond the borders of a single research. In the process, unexpected elements of subjectivity can come into play; in other cases the meaning attributed to them can change in time or can have a role different from what had been expected. Some elements, objects of epistemological analyses, as imposed by a reflexive approach, can become objects of attention also on the phenomenological level.

The Multiple Faces of Reflexive Research Designs

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Karl H. Müller

2015-10-01

Full Text Available Reflexive research can be grouped into five clusters with circular relations between two elements x ↔ x, namely circular relations between observers, between scientific building blocks like concepts, theories or models, between systemic levels, between rules and rule systems or as circular relations or x ↔ y between these four components. By far the most important cluster is the second cluster which becomes reflexive through a re-entry operation RE into a scientific element x and which establishes its circular formation as x(x. Many of the research problems in these five clusters in reflexivity research are still unexplored and pose grand challenges for future research.

A Prototype Analysis of Spanish Indeterminate Reflexive Constructions.

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Turley, Jeffrey S.

1998-01-01

Discussion of the Spanish indeterminate reflexive construction, the impersonal reflexive, finds that prototype theory allows this subjectless Spanish construction to be included within the category of generally subject-bearing indeterminates in Romance languages. (MSE)

Plasticity of the human otolith-ocular reflex

Science.gov (United States)

Wall, C. 3rd; Smith, T. R.; Furman, J. M.

1992-01-01

The eye movement response to earth vertical axis rotation in the dark, a semicircular canal stimulus, can be altered by prior exposure to combined visual-vestibular stimuli. Such plasticity of the vestibulo-ocular reflex has not been described for earth horizontal axis rotation, a dynamic otolith stimulus. Twenty normal human subjects underwent one of two types of adaptation paradigms designed either to attenuate or enhance the gain of the semicircular canal-ocular reflex prior to undergoing otolith-ocular reflex testing with horizontal axis rotation. The adaptation paradigm paired a 0.2 Hz sinusoidal rotation about a vertical axis with a 0.2 Hz optokinetic stripe pattern that was deliberately mismatched in peak velocity. Pre- and post-adaptation horizontal axis rotations were at 60 degrees/s in the dark and produced a modulation in the slow component velocity of nystagmus having a frequency of 0.17 Hz due to putative stimulation of the otolith organs. Results showed that the magnitude of this modulation component response was altered in a manner similar to the alteration in semicircular canal-ocular responses. These results suggest that physiologic alteration of the vestibulo-ocular reflex using deliberately mismatched visual and semicircular canal stimuli induces changes in both canal-ocular and otolith-ocular responses. We postulate, therefore, that central nervous system pathways responsible for controlling the gains of canal-ocular and otolith-ocular reflexes are shared.

Acoustic Reflex Screening of Conductive Hearing Loss for Third Window Disorders.

Science.gov (United States)

Hong, Robert S; Metz, Christopher M; Bojrab, Dennis I; Babu, Seilesh C; Zappia, John; Sargent, Eric W; Chan, Eleanor Y; Naumann, Ilka C; LaRouere, Michael J

2016-02-01

This study examines the effectiveness of acoustic reflexes in screening for third window disorders (eg, superior semicircular canal dehiscence) prior to middle ear exploration for conductive hearing loss. Case series with chart review. Outpatient tertiary otology center. A review was performed of 212 ears with acoustic reflexes, performed as part of the evaluation of conductive hearing loss in patients without evidence of chronic otitis media. The etiology of hearing loss was determined from intraoperative findings and computed tomography imaging. The relationship between acoustic reflexes and conductive hearing loss etiology was assessed. Eighty-eight percent of ears (166 of 189) demonstrating absence of all acoustic reflexes had an ossicular etiology of conductive hearing loss. Fifty-two percent of ears (12 of 23) with at least 1 detectable acoustic reflex had a nonossicular etiology. The positive and negative predictive values for an ossicular etiology were 89% and 57% when acoustic reflexes were used alone for screening, 89% and 39% when third window symptoms were used alone, and 94% and 71% when reflexes and symptoms were used together, respectively. Acoustic reflex testing is an effective means of screening for third window disorders in patients with a conductive hearing loss. Questioning for third window symptoms should complement screening. The detection of even 1 acoustic reflex or third window symptom (regardless of reflex status) should prompt further workup prior to middle ear exploration. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

Reflex epilepsy: triggers and management strategies

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Okudan ZV

2018-01-01

Full Text Available Zeynep Vildan Okudan,1 Çiğdem Özkara2 1Department of Neurology, Bakirkoy Dr Sadi Konuk Education and Research Hospital, 2Department of Neurology and Clinical Neurophysiology, Cerrahpasa Faculty of Medicine, University of Istanbul, Istanbul, Turkey Abstract: Reflex epilepsies (REs are identified as epileptic seizures that are consistently induced by identifiable and objective-specific triggers, which may be an afferent stimulus or by the patient’s own activity. RE may have different subtypes depending on the stimulus characteristic. There are significant clinical and electrophysiologic differences between different RE types. Visual stimuli-sensitive or photosensitive epilepsies constitute a large proportion of the RE and are mainly related to genetic causes. Reflex epilepsies may present with focal or generalized seizures due to specific triggers, and sometimes seizures may occur spontaneously. The stimuli can be external (light flashes, hot water, internal (emotion, thinking, or both and should be distinguished from triggering precipitants, which most epileptic patients could report such as emotional stress, sleep deprivation, alcohol, and menstrual cycle. Different genetic and acquired factors may play a role in etiology of RE. This review will provide a current overview of the triggering factors and management of reflex seizures. Keywords: seizure, reflex epilepsy, photosensitivity, hot water, reading, thinking

Reflex responses of lip muscles in young and older women.

Science.gov (United States)

Wohlert, A B

1996-06-01

The perioral reflex in response to innocuous mechanical stimulation of the lip vermilion was studied in 20 young and 20 older women. Responses to stimuli at the right and left sides of both the upper and lower lips were recorded. Results show significant specificity of response, especially for upper lip sites. Reflex response at the site of stimulation was greatest in amplitude and shortest in latency, followed by response at sites ipsilateral to the site of stimulation. Younger subjects showed greater localizing tendency than older subjects. Stimulation was significantly less likely to produce a reflex response in the older group. When reflex responses did occur, they were significantly lower in amplitude and longer in latency than the responses of the younger group. Nonetheless, reflex responses were common in both groups, with responses at the site of stimulation occurring 78% of the time in older women and 90% of the time in younger women. Every participant showed at least one reflex response to lip stimulation. Results suggest decreasing complexity of synaptic drive to the perioral system in old age but also show that reflexive response does not deteriorate completely, remaining an available element for motor control in normal older women.

Cerebellar interaction with the acoustic reflex.

Science.gov (United States)

Jastreboff, P J

1981-01-01

The involvement of the cerebellar vermis in the acoustic reflex was analyzed in 12 cats, decerebrated or in pentobarbital anesthesia. Anatomical data suggested the existence of a connection of lobules VIII with the ventral cochlear nucleus. Single cell recording and evoked potential techniques demonstrated the existence of the acoustic projection to lobulus VIII. Electrical stimulation of this area changed the tension of the middle ear muscle and caused evoked potential responses in the caudal part of the ventral cochlear nucleus. Electrical stimulation of the motor nucleus of the facial nerve evoked a slow wave in the recording taken from the surrounding of the cochlear round window. A hypothesis is proposed which postulates the involvement of the acoustic reflex in space localization of acoustic stimuli and the action of cerebellar vermis in order to assure the stability and plasticity of the acoustic reflex arc.

Reflex syncope: Diagnosis and treatment

Directory of Open Access Journals (Sweden)

Richard Sutton

2017-12-01

Full Text Available For the diagnosis of reflex syncope, diligent history-building with the patient and a witness is required. In the Emergency Department (ED, the assessment of syncope is a challenge which may be addressed by an ED Observation Unit or by a referral to a Syncope Unit. Hospital admission is necessary for those with life-threatening cardiac conditions although risk stratification remains an unsolved problem. Other patients may be investigated with less urgency by carotid sinus massage (>40 years, tilt testing, and electrocardiogram loop recorder insertion resulting in a clear cause for syncope. Management includes, in general terms, patient education, avoidance of circumstances in which syncope is likely, increase in fluid and salt consumption, and physical counter-pressure maneuvers. In older patients, those that will benefit from cardiac pacing are now well defined. In all patients, the benefit of drug therapy is often disappointing and there remains no ideal drug. A role for catheter ablation may emerge for the highly symptomatic reflex syncope patient. Keywords: Cardiac pacing, Catheter ablation, Diagnosis, Drugs, Management, Reflex syncope

The acoustic reflex threshold in aging ears.

Science.gov (United States)

Silverman, C A; Silman, S; Miller, M H

1983-01-01

This study investigates the controversy regarding the influence of age on the acoustic reflex threshold for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators between Jerger et al. [Mono. Contemp. Audiol. 1 (1978)] and Jerger [J. Acoust. Soc. Am. 66 (1979)] on the one hand and Silman [J. Acoust. Soc. Am. 66 (1979)] and others on the other. The acoustic reflex thresholds for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators were evaluated under two measurement conditions. Seventy-two normal-hearing ears were drawn from 72 subjects ranging in age from 20-69 years. The results revealed that age was correlated with the acoustic reflex threshold for BBN activator but not for any of the tonal activators; the correlation was stronger under the 1-dB than under the 5-dB measurement condition. Also, the mean acoustic reflex thresholds for broadband noise activator were essentially similar to those reported by Jerger et al. (1978) but differed from those obtained in this study under the 1-dB measurement condition.

Soleus and lateral gastrocnemius H-reflexes during standing with unstable footwear.

Science.gov (United States)

Friesenbichler, Bernd; Lepers, Romuald; Maffiuletti, Nicola A

2015-05-01

Unstable footwear has been shown to increase lower extremity muscle activity, but the reflex response to perturbations induced by this intervention is unknown. Twenty healthy subjects stood in stable and unstable footwear conditions (presented randomly) while H-reflex amplitude and background muscle activity were measured in the soleus and lateral gastrocnemius (LG) muscles. Wearing unstable footwear resulted in larger H-reflexes (normalized to the maximal M-wave) for the LG (+12%; P = 0.025), but not for the soleus (+4%; P > 0.05). Background activity of both muscles was significantly higher in the unstable condition. The H-reflex facilitation observed with unstable footwear was unexpected, as challenging postural conditions usually result in reflex depression. Increased muscle activity, decreased presynaptic inhibition, and/or more forward postural position may have (over-)compensated the expected reflex depression. Differences between LG and soleus H-reflex modulation may be due to diverging motor unit recruitment thresholds. © 2015 Wiley Periodicals, Inc.

Optofluidic time-stretch microscopy: recent advances

Science.gov (United States)

Lei, Cheng; Nitta, Nao; Ozeki, Yasuyuki; Goda, Keisuke

2018-04-01

Flow cytometry is an indispensable method for valuable applications in numerous fields such as immunology, pathology, pharmacology, molecular biology, and marine biology. Optofluidic time-stretch microscopy is superior to conventional flow cytometry methods for its capability to acquire high-quality images of single cells at a high-throughput exceeding 10,000 cells per second. This makes it possible to extract copious information from cellular images for accurate cell detection and analysis with the assistance of machine learning. Optofluidic time-stretch microscopy has proven its effectivity in various applications, including microalga-based biofuel production, evaluation of thrombotic disorders, as well as drug screening and discovery. In this review, we discuss the principles and recent advances of optofluidic time-stretch microscopy.

Stretch due to Penile Prosthesis Reservoir Migration

Directory of Open Access Journals (Sweden)

E. Baten

2016-03-01

Full Text Available A 43-year old patient presented to the emergency department with stretch, due to impossible deflation of the penile prosthesis, 4 years after successful implant. A CT-scan showed migration of the reservoir to the left rectus abdominis muscle. Refilling of the reservoir was inhibited by muscular compression, causing stretch. Removal and replacement of the reservoir was performed, after which the prosthesis was well-functioning again. Migration of the penile prosthesis reservoir is extremely rare but can cause several complications, such as stretch.

The "where is it?" reflex: autoshaping the orienting response.

Science.gov (United States)

Buzsáki, G

1982-01-01

The goal of this review is to compare two divergent lines of research on signal-centered behavior: the orienting reflex (OR) and autoshaping. A review of conditioning experiments in animals and humans suggests that the novelty hypothesis of the OR is no longer tenable. Only stimuli that represent biological "relevance" elicit ORs. A stimulus may be relevant a priori (i.e., unconditioned) or as a result of conditioning. Exposure to a conditioned stimulus (CS) that predicts a positive reinforcer causes the animal to orient to it throughout conditioning. Within the CS-US interval, the initial CS-directed orienting response is followed by US-directed tendencies. Experimental evidence is shown that the development and maintenance of the conditioned OR occur in a similar fashion both in response-independent (classical) and response-dependent (instrumental) paradigms. It is proposed that the conditioned OR and the signal-directed autoshaped response are identical. Signals predicting aversive events repel the subject from the source of the CS. It is suggested that the function of the CS is not only to signal the probability of US occurrence, but also to serve as a spatial cue to guide the animal in the environment. PMID:7097153

The "where is it?" reflex: autoshaping the orienting response.

Science.gov (United States)

Buzsáki, G

1982-05-01

The goal of this review is to compare two divergent lines of research on signal-centered behavior: the orienting reflex (OR) and autoshaping. A review of conditioning experiments in animals and humans suggests that the novelty hypothesis of the OR is no longer tenable. Only stimuli that represent biological "relevance" elicit ORs. A stimulus may be relevant a priori (i.e., unconditioned) or as a result of conditioning. Exposure to a conditioned stimulus (CS) that predicts a positive reinforcer causes the animal to orient to it throughout conditioning. Within the CS-US interval, the initial CS-directed orienting response is followed by US-directed tendencies. Experimental evidence is shown that the development and maintenance of the conditioned OR occur in a similar fashion both in response-independent (classical) and response-dependent (instrumental) paradigms. It is proposed that the conditioned OR and the signal-directed autoshaped response are identical. Signals predicting aversive events repel the subject from the source of the CS. It is suggested that the function of the CS is not only to signal the probability of US occurrence, but also to serve as a spatial cue to guide the animal in the environment.

A simple measurement hammer for quantitative reflex studies

NARCIS (Netherlands)

Stam, J.; van Leeuwen, J. R.

1984-01-01

A reflex hammer for measurement of the mechanical stimulus strength was designed. Combined with standard EMG equipment this instrument permits the study of both stimulus-response relations and latencies of myotatic reflexes. Some results in normal subjects are discussed

Ocular vestibular evoked myogenic potential elicited from binaural air-conducted stimulations: clinical feasibility in patients with peripheral vestibular dysfunction.

Science.gov (United States)

Iwasaki, Shinichi; Egami, Naoya; Inoue, Aki; Kinoshita, Makoto; Fujimoto, Chisato; Murofushi, Toshihisa; Yamasoba, Tatsuya

2013-07-01

Ocular vestibular evoked myogenic potentials (oVEMPs) to binaural air-conducted stimulation (ACS) may provide a convenient way of assessing the crossed vestibulo-ocular reflex in patients with vestibular dysfunction as well as in healthy subjects. To investigate the clinical feasibility of using oVEMPs in response to binaural ACS to assess normal subjects and patients with vestibular dysfunction. The study investigated 24 normal subjects (14 men and 10 women, aged from 23 to 60 years) and 14 patients with unilateral peripheral vestibular dysfunction. Each subject underwent oVEMP testing in response to monaural ACS and binaural ACS (500 Hz tone burst, 135 dBSPL). In normal subjects, bilateral oVEMPs were elicited in 75% of subjects in response to monaural ACS and in 91% in response to binaural ACS. Asymmetry ratios (ARs) of the responses to binaural ACS were significantly smaller than those of the responses to monaural ACS (p binaural ACS. Approximately 30% of patients showed reduced ARs to binaural ACS relative to monaural ACS, primarily due to contamination by uncrossed responses elicited in healthy ears.

Reflexive fatherhood in everyday life

DEFF Research Database (Denmark)

Westerling, Allan

2015-01-01

This article looks at fathering practices in Denmark, using the findings from a research project on everyday family life in Denmark. It takes a social psychological perspective and employs discursive psychology and theories about reflexive modernisation. It shows how fathers orient towards intimacy...... in their relationships with their children. Moreover, it discusses how fathers’ relatedness reflects individualisation and detraditionalisation. It is argued that reflexive modernisation entails subjective orientations that enable novel pathways to intimacy in contemporary father–child relationships. Through...... this analysis and discussion, the article offers a way to understand the complexities of fathering in everyday life from the perspective of fathers....

Reflexive intergroup bias in third-party punishment.

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Yudkin, Daniel A; Rothmund, Tobias; Twardawski, Mathias; Thalla, Natasha; Van Bavel, Jay J

2016-11-01

Humans show a rare tendency to punish norm-violators who have not harmed them directly-a behavior known as third-party punishment. Research has found that third-party punishment is subject to intergroup bias, whereby people punish members of the out-group more severely than the in-group. Although the prevalence of this behavior is well-documented, the psychological processes underlying it remain largely unexplored. Some work suggests that it stems from people's inherent predisposition to form alliances with in-group members and aggress against out-group members. This implies that people will show reflexive intergroup bias in third-party punishment, favoring in-group over out-group members especially when their capacity for deliberation is impaired. Here we test this hypothesis directly, examining whether intergroup bias in third-party punishment emerges from reflexive, as opposed to deliberative, components of moral cognition. In 3 experiments, utilizing a simulated economic game, we varied participants' group relationship to a transgressor, measured or manipulated the extent to which they relied on reflexive or deliberative judgment, and observed people's punishment decisions. Across group-membership manipulations (American football teams, nationalities, and baseball teams) and 2 assessments of reflexive judgment (response time and cognitive load), reflexive judgment heightened intergroup bias, suggesting that such bias in punishment is inherent to human moral cognition. We discuss the implications of these studies for theories of punishment, cooperation, social behavior, and legal practice. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Snout and Visual Rooting Reflexes in Infantile Autism. Brief Report.

Science.gov (United States)

Minderaa, Ruud B.; And Others

1985-01-01

The authors conducted extensive neurological evaluations of 42 autistic individuals and were surprised to discover a consistently positive snout reflex in most of them. Difficulties with assessing the reflex are noted. The authors then reassessed the Ss for a series of primitive reflexes which are interpreted as signs of diffuse cortical brain…

The influence of reflexive educational environment on students ...

African Journals Online (AJOL)

The influence of reflexive educational environment on students' reflection development in ... based on them) from which, as they integrate, a reflexive personality style is developed. ... (narrative, dialogical, cognitive and axiological) are the factors influencing the outcome of social adaptation. ... AJOL African Journals Online.

Mechanical stretching for tissue engineering: two-dimensional and three-dimensional constructs.

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Riehl, Brandon D; Park, Jae-Hong; Kwon, Il Keun; Lim, Jung Yul

2012-08-01

Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols.

Immediate effects of different types of stretching exercises on badminton jump smash.

Science.gov (United States)

Jang, Hwi S; Kim, Daeho; Park, Jihong

2018-01-01

Since different types of stretching exercises may alter athletic performance, we compared the effects of three types of stretching exercises on badminton jump smash. Sixteen male collegiate badminton players performed one of three different stretching exercises in a counterbalanced order on different days. Static stretching had seven typical stretches, while dynamic stretching involved nine dynamic movements, and resistance dynamic stretching was performed with weighted vests and dumbbells. Before and after each stretching exercise, subjects performed 20 trials of jump smashes. Dependent measurements were the jump heights during jump smashes, velocities of jump-smashed shuttlecocks, and drop point of jump-smashed shuttlecocks. To test the effects of each stretching exercise, we performed mixed model ANOVAs and calculated between-time effect sizes (ES). Each stretching exercise improved the jump heights during jump smashes (type main effect: F(2,75)=1.19, P=0.31; static stretching: 22.1%, Pjump-smashed shuttlecocks (type main effect: F(2,75)=2.18, P=0.12; static stretching: 5.7%, P=0.61, ES=0.39; dynamic stretching: 3.4%, P=0.94, ES=0.28; resistance dynamic stretching: 6%, P=0.50, ES=0.66). However, there were no differences among the stretching exercises for any measurement. The drop point of jump-smashed shuttlecocks did not change (interaction: F(2,75)=0.88, P=0.42). All stretching exercises improved badminton jump smash performance, but we could not determine the best protocol. Since badminton requires high-speed movement and explosive force, we suggest performing dynamic stretching or resistance dynamic stretching.

Lattice stretching bistability and dynamic heterogeneity

DEFF Research Database (Denmark)

Christiansen, Peter Leth; Savin, A. V.; Zolotaryuk, A. V.

2012-01-01

A simple one-dimensional lattice model is suggested to describe the experimentally observed plateau in force-stretching diagrams for some macromolecules. This chain model involves the nearest-neighbor interaction of a Morse-like potential (required to have a saturation branch) and a harmonic second......-neighbor coupling. Under an external stretching applied to the chain ends, the intersite Morse-like potential results in the appearance of a double-well potential within each chain monomer, whereas the interaction between the second neighbors provides a homogeneous bistable (degenerate) ground state, at least...... stretched bonds with a double-well potential. This case allows us to explain the existence of a plateau in the force-extension diagram for DNA and α-helix protein. Finally, the soliton dynamics are studied in detail....

Comparing the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men.

Science.gov (United States)

Ferguson, Steven L; Kim, Eonho; Seo, Dong-Il; Bemben, Michael G

2013-12-01

This study compared the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men. Twenty-one men were randomly assigned to vibration-stretching (VS; n = 8), vibration only (VO; n = 6), or stretching only (SO; n = 7) groups that trained 3 times per week for 3 weeks. All 3 groups performed 9 total sets of 30-second stretches. The VS group performed four 30-second upper-body vibration exercises and five 30-second upper-body stretching exercises. The VO group performed nine 30-second upper-body vibration exercises. The SO group performed nine 30-second upper-body stretching exercises. Shoulder flexion (SF), shoulder extension (SE), and shoulder transverse extension (STE) were assessed by a Leighton Flexometer and back scratch tests bilaterally (BSR, BSL) were measured via tape measure. A 1-way analysis of variance (ANOVA) evaluated groups at baseline and a 2-way repeated-measures ANOVA evaluated the interventions over time. At baseline, there were no group differences in age, height, or weight. There was a significant (p alone or combined with stretching, is a viable alternative to a standard stretching routine when attempting to increase shoulder flexibility. Adding vibration training to a flexibility regimen may improve the likelihood of regularly performing flexibility sessions because of increased variety.

[Human physiology: images and practices of the reflex].

Science.gov (United States)

Wübben, Yvonne

2010-01-01

The essay examines the function of visualizations and practices in the formation of the reflex concept from Thomas Willis to Marshall Hall. It focuses on the specific form of reflex knowledge that images and practices can contain. In addition, the essay argues that it is through visual representations and experimental practices that technical knowledge is transferred to the field of human reflex physiology. When using technical metaphors in human physiology authors often seem to feel obliged to draw distinctions between humans, machines and animals. On closer scrutiny, these distinctions sometimes fail to establish firm borders between the human and the technical.

Nociceptive flexion reflexes during analgesic neurostimulation in man.

Science.gov (United States)

García-Larrea, L; Sindou, M; Mauguière, F

1989-11-01

Nociceptive flexion reflexes of the lower limbs (RIII responses) have been studied in 21 patients undergoing either epidural (DCS, n = 16) or transcutaneous (TENS, n = 5) analgesic neurostimulation (AN) for chronic intractable pain. Flexion reflex RIII was depressed or suppressed by AN in 11 patients (52.4%), while no modification was observed in 9 cases and a paradoxical increase during AN was evidenced in 1 case. In all but 2 patients, RIII changes were rapidly reversible after AN interruption. RIII depression was significantly associated with subjective pain relief, as assessed by conventional self-rating; moreover, in 2 patients it was possible to ameliorate the pain-suppressing effects of AN by selecting those stimulation parameters (intensity and frequency) that maximally depressed nociceptive reflex RIII. We recorded 2 cases of RIII attenuation after contralateral neurostimulation. AN appeared to affect nociceptive reflexes rather selectively, with no or very little effect on other cutaneous, non-nociceptive responses. Recording of RIII reflexes is relatively simple to implement as a routine paraclinical procedure. It facilitates the objective assessment of AN efficacy and may help to choose the most appropriate parameters of neurostimulation. In addition, RIII behavior in patients could be relevant to the understanding of some of the mechanisms involved in AN-induced pain relief.

Role of ionotropic GABA, glutamate and glycine receptors in the tonic and reflex control of cardiac vagal outflow in the rat

Directory of Open Access Journals (Sweden)

Goodchild Ann K

2010-10-01

Full Text Available Abstract Background Cardiac vagal preganglionic neurons (CVPN are responsible for the tonic, reflex and respiratory modulation of heart rate (HR. Although CVPN receive GABAergic and glutamatergic inputs, likely involved in respiratory and reflex modulation of HR respectively, little else is known regarding the functions controlled by ionotropic inputs. Activation of g-protein coupled receptors (GPCR alters these inputs, but the functional consequence is largely unknown. The present study aimed to delineate how ionotropic GABAergic, glycinergic and glutamatergic inputs contribute to the tonic and reflex control of HR and in particular determine which receptor subtypes were involved. Furthermore, we wished to establish how activation of the 5-HT1A GPCR affects tonic and reflex control of HR and what ionotropic interactions this might involve. Results Microinjection of the GABAA antagonist picrotoxin into CVPN decreased HR but did not affect baroreflex bradycardia. The glycine antagonist strychnine did not alter HR or baroreflex bradycardia. Combined microinjection of the NMDA antagonist, MK801, and AMPA antagonist, CNQX, into CVPN evoked a small bradycardia and abolished baroreflex bradycardia. MK801 attenuated whereas CNQX abolished baroreceptor bradycardia. Control intravenous injections of the 5-HT1A agonist 8-OH-DPAT evoked a small bradycardia and potentiated baroreflex bradycardia. These effects were still observed following microinjection of picrotoxin but not strychnine into CVPN. Conclusions We conclude that activation of GABAA receptors set the level of HR whereas AMPA to a greater extent than NMDA receptors elicit baroreflex changes in HR. Furthermore, activation of 5-HT1A receptors evokes bradycardia and enhances baroreflex changes in HR due to interactions with glycinergic neurons involving strychnine receptors. This study provides reference for future studies investigating how diseases alter neurochemical inputs to CVPN.

Bruxism: Is There an Indication for Muscle-Stretching Exercises?

Science.gov (United States)

Gouw, Simone; de Wijer, Anton; Creugers, Nico Hj; Kalaykova, Stanimira I

Bruxism is a common phenomenon involving repetitive activation of the masticatory muscles. Muscle-stretching exercises are a recommended part of several international guidelines for musculoskeletal disorders and may be effective in management of the jaw muscle activity that gives rise to bruxism. However, most studies of muscle-stretching exercises have mainly focused on their influence on performance (eg, range of motion, coordination, and muscle strength) of the limb or trunk muscles of healthy individuals or individuals with sports-related injuries. Very few have investigated stretching of the human masticatory muscles and none muscle-stretching exercises in the management of (sleep) bruxism. This article reviews the literature on muscle-stretching exercises and their potential role in the management of sleep bruxism or its consequences in the musculoskeletal system.

Correlation of augmented startle reflex with brainstem electrophysiological responses in Tay-Sachs disease.

Science.gov (United States)

Nakamura, Sadao; Saito, Yoshiaki; Ishiyama, Akihiko; Sugai, Kenji; Iso, Takashi; Inagaki, Masumi; Sasaki, Masayuki

2015-01-01

To clarify the evolution of an augmented startle reflex in Tay-Sachs disease and compare the temporal relationship between this reflex and brainstem evoked potentials. Clinical and electrophysiological data from 3 patients with Tay-Sachs disease were retrospectively collected. The augmented startle reflex appeared between the age of 3 and 17 months and disappeared between the age of 4 and 6 years. Analysis of brainstem auditory evoked potentials revealed that poor segregation of peak I, but not peak III, coincided with the disappearance of the augmented startle reflex. A blink reflex with markedly high amplitude was observed in a patient with an augmented startle reflex. The correlation between the augmented startle reflex and the preservation of peak I but not peak III supports the theory that the superior olivary nucleus is dispensable for this reflex. The blink reflex with high amplitudes may represent augmented excitability of reticular formation at the pontine tegmentum in Tay-Sachs disease, where the pattern generators for the augmented startle and blink reflexes may functionally overlap. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Stretch induced endothelin-1 secretion by adult rat astrocytes involves calcium influx via stretch-activated ion channels (SACs)

International Nuclear Information System (INIS)

Ostrow, Lyle W.; Suchyna, Thomas M.; Sachs, Frederick

2011-01-01

Highlights: → Endothelin-1 expression by adult rat astrocytes correlates with cell proliferation. → Stretch-induced ET-1 is inhibited by GsMtx-4, a specific inhibitor of Ca 2+ permeant SACs. → The less specific SAC inhibitor streptomycin also inhibits ET-1 secretion. → Stretch-induced ET-1 production depends on a calcium influx. → SAC pharmacology may provide a new class of therapeutic agents for CNS pathology. -- Abstract: The expression of endothelins (ETs) and ET-receptors is often upregulated in brain pathology. ET-1, a potent vasoconstrictor, also inhibits the expression of astrocyte glutamate transporters and is mitogenic for astrocytes, glioma cells, neurons, and brain capillary endothelia. We have previously shown that mechanical stress stimulates ET-1 production by adult rat astrocytes. We now show in adult astrocytes that ET-1 production is driven by calcium influx through stretch-activated ion channels (SACs) and the ET-1 production correlates with cell proliferation. Mechanical stimulation using biaxial stretch ( 2+ threshold. This coupling of mechanical stress to the astrocyte endothelin system through SACs has treatment implications, since all pathology deforms the surrounding parenchyma.

Student Mobility and Transnational Social Ties as Factors of Reflexivity

Directory of Open Access Journals (Sweden)

Tea Golob

2018-03-01

Full Text Available The article seeks to develop and apply new quantitative measurement instruments capable of significantly improving understanding of the relationship between the transnational mobility and transnational social ties of students, along with their reflexive capacities. With a focus on students building their personal networks, educational and professional activities that extend beyond the nation’s borders and organising their day-to-day routines in transnational social spaces, we analyse the role of mobility in their reflexive capacities. Applying a tool that is line with Archer’s theory and indicators to measure reflexivity, and transnational social ties as proposed by Molina et al., we analyse data collected via an on-line survey questionnaire administered to Slovenian students. In addition, students from the Middle East (Lebanon and the USA (Hawai’i are added for comparative purposes. The results of path analysis show the Slovenian students’ mobility as such implies higher scores for meta reflexivity, combined with lower scores for communicative and fractured reflexivity. Further, social transactions reaching beyond one’s physical localities in terms of transnational social ties implies they have higher levels of reflexivity in general.

BSDB: the Biomolecule Stretching Database

Science.gov (United States)

Cieplak, Marek; Sikora, Mateusz; Sulkowska, Joanna I.; Witkowski, Bartlomiej

2011-03-01

Despite more than a decade of experiments on single biomolecule manipulation, mechanical properties of only several scores of proteins have been measured. A characteristic scale of the force of resistance to stretching, Fmax , has been found to range between ~ 10 and 480 pN. The Biomolecule Stretching Data Base (BSDB) described here provides information about expected values of Fmax for, currently, 17 134 proteins. The values and other characteristics of the unfolding proces, including the nature of identified mechanical clamps, are available at www://info.ifpan.edu.pl/BSDB/. They have been obtained through simulations within a structure-based model which correlates satisfactorily with the available experimental data on stretching. BSDB also lists experimental data and results of the existing all-atom simulations. The database offers a Protein-Data-Bank-wide guide to mechano-stability of proteins. Its description is provided by a forthcoming Nucleic Acids Research paper. Supported by EC FUNMOL project FP7-NMP-2007-SMALL-1, and European Regional Development Fund: Innovative Economy (POIG.01.01.02-00-008/08).

D1 and D2 Inhibitions of the Soleus H-Reflex Are Differentially Modulated during Plantarflexion Force and Position Tasks.

Directory of Open Access Journals (Sweden)

Fernando Henrique Magalhães

Full Text Available Presynaptic inhibition (PSI has been shown to modulate several neuronal pathways of functional relevance by selectively gating the connections between sensory inputs and spinal motoneurons, thereby regulating the contribution of the stretch reflex circuitry to the ongoing motor activity. In this study, we investigated whether a differential regulation of Ia afferent inflow by PSI may be associated with the performance of two types of plantarflexion sensoriomotor tasks. The subjects (in a seated position controlled either: 1 the force level exerted by the foot against a rigid restraint (force task, FT; or 2 the angular position of the ankle when sustaining inertial loads (position task, PT that required the same level of muscle activation observed in FT. Subjects were instructed to maintain their force/position at target levels set at ~10% of maximum isometric voluntary contraction for FT and 90° for PT, while visual feedback of the corresponding force/position signals were provided. Unconditioned H-reflexes (i.e. control reflexes and H-reflexes conditioned by electrical pulses applied to the common peroneal nerve with conditioning-to-test intervals of 21 ms and 100 ms (corresponding to D1 and D2 inhibitions, respectively were evoked in a random fashion. A significant main effect for the type of the motor task (FT vs PT (p = 0.005, η2p = 0.603 indicated that PTs were undertaken with lower levels of Ia PSI converging onto the soleus motoneuron pool. Additionally, a significant interaction between the type of inhibition (D1 vs D2 and the type of motor task (FT vs PT (p = 0.038, η2p = 0.395 indicated that D1 inhibition was associated with a significant reduction in PSI levels from TF to TP (p = 0.001, η2p = 0.731, whereas no significant difference between the tasks was observed for D2 inhibition (p = 0.078, η2p = 0.305. These results suggest that D1 and D2 inhibitions of the soleus H-reflex are differentially modulated during the performance of

Reflexivity: The Creation of Liminal Spaces--Researchers, Participants, and Research Encounters.

Science.gov (United States)

Enosh, Guy; Ben-Ari, Adital

2016-03-01

Reflexivity is defined as the constant movement between being in the phenomenon and stepping outside of it. In this article, we specify three foci of reflexivity--the researcher, the participant, and the encounter--for exploring the interview process as a dialogic liminal space of mutual reflection between researcher and participant. Whereas researchers' reflexivity has been discussed extensively in the professional discourse, participants' reflexivity has not received adequate scholarly attention, nor has the promise inherent in reflective processes occurring within the encounter. © The Author(s) 2015.

Probabilities on Streams and Reflexive Games

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Andrew Schumann

2014-01-01

Full Text Available Probability measures on streams (e.g. on hypernumbers and p-adic numbers have been defined. It was shown that these probabilities can be used for simulations of reflexive games. In particular, it can be proved that Aumann's agreement theorem does not hold for these probabilities. Instead of this theorem, there is a statement that is called the reflexion disagreement theorem. Based on this theorem, probabilistic and knowledge conditions can be defined for reflexive games at various reflexion levels up to the infinite level. (original abstract

Researching Reflexively With Patients and Families: Two Studies Using Video-Reflexive Ethnography to Collaborate With Patients and Families in Patient Safety Research.

Science.gov (United States)

Collier, Aileen; Wyer, Mary

2016-06-01

Patient safety research has to date offered few opportunities for patients and families to be actively involved in the research process. This article describes our collaboration with patients and families in two separate studies, involving end-of-life care and infection control in acute care. We used the collaborative methodology of video-reflexive ethnography, which has been primarily used with clinicians, to involve patients and families as active participants and collaborators in our research. The purpose of this article is to share our experiences and findings that iterative researcher reflexivity in the field was critical to the progress and success of each study. We present and analyze the complexities of reflexivity-in-the-field through a framework of multilayered reflexivity. We share our lessons here for other researchers seeking to actively involve patients and families in patient safety research using collaborative visual methods. © The Author(s) 2015.

Learning reflexively from a health promotion professional development program in Canada.

Science.gov (United States)

Tremblay, Marie-Claude; Richard, Lucie; Brousselle, Astrid; Beaudet, Nicole

2014-09-01

In recent decades, reflexivity has received much attention in the professional education and training literature, especially in the public health and health promotion fields. Despite general agreement on the importance of reflexivity, there appears to be no consensus on how to assess reflexivity or to conceptualize the different forms developed among professionals and participants of training programs. This paper presents an analysis of the reflexivity outcomes of the Health Promotion Laboratory, an innovative professional development program aimed at supporting practice changes among health professionals by fostering competency development and reflexivity. More specifically, this paper explores the difference between two levels of reflexivity (formative and critical) and highlights some implications of each for practice. Data were collected through qualitative interviews with participants from two intervention sites. Results showed that involvement in the Health Promotion Laboratory prompted many participants to modify their vision of their practice and professional role, indicating an impact on reflexivity. In many cases, new understandings seem to have played a formative function in enabling participants to improve their practice and their role as health promoters. The reflective process also served a critical function culminating in a social and moral understanding of the impacts on society of the professionals' practices and roles. This type of outcome is greatly desired in health promotion, given the social justice and equity concerns of this field of practice. By redefining the theoretical concept of reflexivity on two levels and discussing their impacts on practice, this study supports the usefulness of both levels of reflexivity. © The Author (2013). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Study of Achilles Tendon Reflex in Normal Korean and Various Thyroid Diseases

International Nuclear Information System (INIS)

Kang, Jin Yung; Kim, Kwang Won; Yae, Sung Bo; Lee, Hong Kyu; Koh, Chang Soon

1975-01-01

In an attempt to establish the diagnostic value of Achilles tendon reflex and to determine the normal value of Achilles tendon reflex time in normal Korean, the author measured the Achilles tendon reflex time by photomotograph. This study was carried out in 272 cases with various thyroid diseases and 340 normal Korean. 1) The Achilles tendon reflex time in normal Korean was like this, between 11 years old and 20 years old; male (62 cases); 250±27 msec, female (36 cases); 266±27 msec, between 21 years old and 30 years old; male (38 cases); 271±27 msec, female (21 cases); 284±27 msec, between 31 years old and 40 years old; male (26 cases); 275±25 msec, female (29 cases); 291±27 msec, between 41 years old and 50 years old; male (20 cases); 286±35 msec, female (24 cases); 307±42 msec, between 51 years old and 60 years old, male (20 cases); 296±33 msec, female (20 cases); 318±46 msec, over 61 years; male (24 cases) 301±33 msec, female (20 cases); 325±35 msec. The Achilles tendon reflex time was delayed with increasing age and delayed in the female. 2) The Achilles tendon reflex time was markedly shortened to 221±20 msec in untreated hyperthyroidism. 3) The Achilles tendon reflex time was markedly delayed to 435±59 msec in hypothyroidism. 4) The Achilles tendon reflex time was not changed significantly in other thyroid diseases with norms thyroid function. 5) The Achilles tendon reflex time showed good correlationship with ETR, T 3 RU, 131 I thyroid uptake and serum TSH. 6) Reproducibility of Achilles tendon reflex time was good, and no significant difference between left and right was noted. 7) Diagnostic accuracy of Achilles tendon reflex time was 71% in hyperthyroidism and 90% in hypothyroidism. 8) The Achilles tendon reflex time showed useful test to evaluate the clinical course of the hyperthyroidism.

Anticausatives are semantically reflexive in Norwegian, but not in English

Directory of Open Access Journals (Sweden)

Björn Lundquist

2016-11-01

Full Text Available In this paper we will discuss cross-linguistic variation in semantic entailment patterns in causative alternations. Previous work has probed this issue with data from elicited semantic judgements on paired linguistic forms, often involving linguistic negation and contradiction. We contribute to the debate in the form of a related psycholinguistic experiment that taps into direct judgements of truth conditions based on visualized scenarios. The stimulus consisted of video sequences of agents causing events, and the task involved answering a Yes-No question based on the anticausative/inchoative alternant. We were therefore able to test two languages, Norwegian and English, with the very same stimuli and directly compare the judgements. Based on our results, we will argue that the causative alternation is qualitatively different in the two languages. More specifically, the results support an entailment relation between the causative and its anticausative counterpart in English, as predicted by the whole class of “causer-less” analyses (Levin & Rappaport Hovav 1995; Ramchand 2008; Reinhart & Siloni 2005 in the literature. In contrast to this, our results support a reflexive analysis of anticausatives in Norwegian (Chierchia 2004; Koontz-Garboden 2009, where no such entailment holds.

Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control During Variable Radius Centrifugation Following Space Flight

Science.gov (United States)

Wood, Scott J.; Clarke, A. H.; Rupert, A. H.; Harm, D. L.; Clement, G. R.

2009-01-01

Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, less than 20 cm radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. One result of this study will be to characterize the variability (gain, asymmetry) in both otolith-ocular responses and motion perception during variable radius centrifugation, and measure the time course of post-flight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved

Avian reflex and electroencephalogram responses in different states of consciousness.

Science.gov (United States)

Sandercock, Dale A; Auckburally, Adam; Flaherty, Derek; Sandilands, Victoria; McKeegan, Dorothy E F

2014-06-22

Defining states of clinical consciousness in animals is important in veterinary anaesthesia and in studies of euthanasia and welfare assessment at slaughter. The aim of this study was to validate readily observable reflex responses in relation to different conscious states, as confirmed by EEG analysis, in two species of birds under laboratory conditions (35-week-old layer hens (n=12) and 11-week-old turkeys (n=10)). We evaluated clinical reflexes and characterised electroencephalograph (EEG) activity (as a measure of brain function) using spectral analyses in four different clinical states of consciousness: conscious (fully awake), semi-conscious (sedated), unconscious-optimal (general anaesthesia), unconscious-sub optimal (deep hypnotic state), as well as assessment immediately following euthanasia. Jaw or neck muscle tone was the most reliable reflex measure distinguishing between conscious and unconscious states. Pupillary reflex was consistently observed until respiratory arrest. Nictitating membrane reflex persisted for a short time (power (PTOT) significantly increased, whereas median (F50) and spectral edge (F95) frequencies significantly decreased. This study demonstrates that EEG analysis can differentiate between clinical states (and loss of brain function at death) in birds and provides a unique integration of reflex responses and EEG activity. Copyright © 2014 Elsevier Inc. All rights reserved.

Static stretching does not alter pre and post-landing muscle activation

Directory of Open Access Journals (Sweden)

Moss Wesley R

2011-05-01

Full Text Available Abstract Background Static stretching may result in various strength and power deficiencies. Prior research has not determined, however, if static stretching causes a change in muscle activation during a functional task requiring dynamic stability. The purpose of this study was to determine if static stretching has an effect on mean pre and postlanding muscle (vastus medialis VM, vastus lateralis VL, medial hamstring MH, and biceps femoris BF activity. Methods 26 healthy, physically active subjects were recruited, from which 13 completed a 14-day static stretching regimen for the quadriceps and hamstrings. Using the data from the force plate and EMG readings, a mean of EMG amplitude was calculated for 150 msec before and after landing. Each trial was normalized to an isometric reference position. Means were calculated for the VM, VL, MH, and BF from 5 trials in each session. Measures were collected pre, immediately following the 1st stretching session, and following 2 weeks of stretching. Results A 14-day static stretching regimen resulted in no significant differences in pre or postlanding mean EMG amplitude during a drop landing either acutely or over a 14-day period. Conclusions Static stretching, done acutely or over a 14-day period does not result in measurable differences of mean EMG amplitude during a drop landing. Static stretching may not impede dynamic stability of joints about which stretched muscles cross.

Absence of sensory function in the reconstructed anterior cruciate ligament

DEFF Research Database (Denmark)

Krogsgaard, Michael R; Fischer-Rasmussen, Torsten; Dyhre-Poulsen, Poul

2011-01-01

Cruciate ligaments provide sensory information that cause excitatory as well as inhibitory effects to the activity of the muscles around the knee. The aim of the study was to determine whether these muscular reflexes are reestablished after anterior cruciate ligament (ACL) re-construction. Wire...... and the sensory threshold was determined. Stimulus amplitudes were increased to 1.5-2.0 times the sensory threshold, and inhibitory reflexes could be elicited from PCL in the quadriceps during active extension and in the hamstrings muscles during active flexion in all patients. Subsequently the ACL re...... amplitudes necessary to elicit reflexes from the ACL re-constructions were 2, 9 times higher than amplitudes that elicited reflexes from the PCL. Sensation and afferent reflex activity required a much stronger stimulus in the ACL graft compared to normal PCL. We suggest that the reason...

Intrapartum synthetic oxytocin reduce the expression of primitive reflexes associated with breastfeeding.

Science.gov (United States)

Marín Gabriel, Miguel A; Olza Fernández, Ibone; Malalana Martínez, Ana M; González Armengod, Carmen; Costarelli, Valeria; Millán Santos, Isabel; Fernández-Cañadas Morillo, Aurora; Pérez Riveiro, Pilar; López Sánchez, Francisco; García Murillo, Lourdes

2015-05-01

Several synthetic peptide manipulations during the time surrounding birth can alter the specific neurohormonal status in the newborn brain. This study is aimed at assessing whether intrapartum oxytocin administration has any effect on primitive neonatal reflexes and determining whether such an effect is dose-dependent. A cohort prospective study was conducted at a tertiary hospital. Mother-infant dyads who received intrapartum oxytocin (n=53) were compared with mother-infant dyads who did not receive intrapartum oxytocin (n=45). Primitive neonatal reflexes (endogenous, antigravity, motor, and rhythmic reflexes) were quantified by analyzing videotaped breastfeeding sessions in a biological nurturing position. Two observers blind to the group assignment and the oxytocin dose analyzed the videotapes and assesed the newborn's state of consciousness according to the Brazelton scale. The release of all rhythmic reflexes (p=0.01), the antigravity reflex (p=0.04), and total primitive neonatal reflexes (p=0.02) in the group exposed to oxytocin was lower than in the group not exposed to oxytocin. No correlations were observed between the dose of oxytocin administered and the percentage of primitive neonatal reflexes released (r=0.03; p=0.82). Intrapartum oxytocin administration might inhibit the expression of several primitive neonatal reflexes associated with breastfeeding. This correlation does not seem to be dose-dependent.

Summary of the stretching tectonics research

International Nuclear Information System (INIS)

Yu Dagan

1994-01-01

The rise of stretching tectonics is established on the basis of recent structural geology theory, the establishment of metamorphic nucleus complex structural model on one hand plays an important promoting art to the development of stretching structure, on the other hand, it needs constant supplement and perfection in practice. Metamorphic nucleus complex is the carrier of comparatively deep geological information in vertical section of the crust and has wide distribution in the era of south China. Evidently, it can be taken as the 'key' to understanding the deep and studying the basement, Strengthening the study will play the important promoting role to the deep prospecting. The study of stretching tectonics is not only limited within the range of structure and metamorphism, but combine with the studies of sedimentation, magmatism, metamorphism and mineralization, thus form a new field of tectonic geology of self-developing system

EFFECT OF DIFFERENT STRETCHING PROTOCOLS ON VERTICAL JUMP PERFORMANCE

Directory of Open Access Journals (Sweden)

Emre Serin

2018-04-01

Full Text Available This study aimed to examine the effect of different stretching exercises on vertical jump performance. A total of 14 national male athletes sporting in the elite level took part in the study. The age average of the participants was 20.25±1.03 year, the average height was 1.80±.08 m, the average body weight was 77.14±18.91 kg, average of sporting age was 9.87±3.31 year and the average number of participation in international games was 10.0±3.31. As stretching protocol: Method 1 (5 minutes of jogging and 2 minutes of active rest followed by Method 2 (static stretching for 4 different muscle groups 3 repetitions for 15 seconds of static stretching, rest for 10 seconds between groups and then consecutively, Method 3 (Dynamic stretching exercises with 3 repetitions for 15 seconds and 10 seconds rest between different muscle groups were applied in the study. The vertical jump performance before and after different stretching exercises of the participants was determined by means of the vertical jump test using the smart speed lite system. Before and after the training of all athletes, HR was recorded with a heart rate monitor (RS 800, Polar Vantage NV, Polar Electro Oy, Finland with 5 seconds intervals. Before the study, the chest band of the heartbeat monitor was placed on the chest of the athlete and the HR was recorded from the monitor. SPSS 15.0 statistical package program was used for evaluation and calculation of the data. In this study in addition to descriptive statistics (mean and standard deviation paired samples t-test was used to determine the difference between the vertical jump performance of the participants before and after different stretching exercises. As a result, this study showed that; applying the dynamic and static stretching exercises consecutively affected the vertical jump performance 4.5 cm positively (p<.05. It is suggested that different dynamic and static stretching exercises should be included in the vertical jump.

Prepulse inhibition and facilitation of the postauricular reflex, a vestigial remnant of pinna startle.

Science.gov (United States)

Hackley, Steven A; Ren, Xi; Underwood, Amy; Valle-Inclán, Fernando

2017-04-01

If the postauricular reflex (PAR) is to be used effectively in studies of emotion and attention, its sensitivity to basic modulatory effects such as prepulse inhibition and facilitation must be determined. Two experiments were carried out with healthy young adults to assess the effects of transient and sustained visual prestimuli on the pinna-flexion response to trains of startle probes. In the first experiment, participants passively viewed a small white square. It was displayed from 1,000 ms prior to onset of a train of noise bursts until the end of that train. Relative to no-prepulse control trials, PAR amplitude was inhibited, possibly due to the withdrawal of attentional resources from the auditory modality. In the second experiment, participants performed a visual oddball task in which irrelevant trains of startle probes followed most briefly displayed task stimuli (checkerboards). Prepulse inhibition was observed when a transient stimulus preceded the first probe at a lead time of 100 ms. Amplitude facilitation was observed at longer lead times. In addition to documenting the existence of prepulse inhibition and facilitation, the data suggest that the PAR is not elicited by visual stimuli, that temporal expectancy does not influence its amplitude or latency, and that this vestigial microreflex is resistant to habituation. Results are interpreted in light of a recent theory that the human PAR is a highly degraded pinna startle, in which the reflex arc no longer includes the startle center (nucleus reticularis pontis caudalis). © 2017 Society for Psychophysiological Research.

Reflex epileptic mechanisms in humans: Lessons about natural ictogenesis.

Science.gov (United States)

Wolf, Peter

2017-06-01

The definition of reflex epileptic seizures is that specific seizure types can be triggered by certain sensory or cognitive stimuli. Simple triggers are sensory (most often visual, more rarely tactile or proprioceptive; simple audiogenic triggers in humans are practically nonexistent) and act within seconds, whereas complex triggers like praxis, reading and talking, and music are mostly cognitive and work within minutes. The constant relation between a qualitatively, often even quantitatively, well-defined stimulus and a specific epileptic response provides unique possibilities to investigate seizure generation in natural human epilepsies. For several reflex epileptic mechanisms (REMs), this has been done. Reflex epileptic mechanisms have been reported less often in focal lesional epilepsies than in idiopathic "generalized" epilepsies (IGEs) which are primarily genetically determined. The key syndrome of IGE is juvenile myoclonic epilepsy (JME), where more than half of the patients present reflex epileptic traits (photosensitivity, eye closure sensitivity, praxis induction, and language-induced orofacial reflex myocloni). Findings with multimodal investigations of cerebral function concur to indicate that ictogenic mechanisms in IGEs largely (ab)use preexisting functional anatomic networks (CNS subsystems) normally serving highly complex physiological functions (e.g., deliberate complex actions and linguistic communication) which supports the concept of system epilepsy. Whereas REMs in IGEs, thus, are primarily function-related, in focal epilepsies, they are primarily localization-related. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic". Copyright © 2015 Elsevier Inc. All rights reserved.

FEFsem neuronal response during combined volitional and reflexive pursuit.

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Bakst, Leah; Fleuriet, Jérome; Mustari, Michael J

2017-05-01

Although much is known about volitional and reflexive smooth eye movements individually, much less is known about how they are coordinated. It is hypothesized that separate cortico-ponto-cerebellar loops subserve these different types of smooth eye movements. Specifically, the MT-MST-DLPN pathway is thought to be critical for ocular following eye movements, whereas the FEF-NRTP pathway is understood to be vital for volitional smooth pursuit. However, the role that these loops play in combined volitional and reflexive behavior is unknown. We used a large, textured background moving in conjunction with a small target spot to investigate the eye movements evoked by a combined volitional and reflexive pursuit task. We also assessed the activity of neurons in the smooth eye movement subregion of the frontal eye field (FEFsem). We hypothesized that the pursuit system would show less contribution from the volitional pathway in this task, owing to the increased involvement of the reflexive pathway. In accordance with this hypothesis, a majority of FEFsem neurons (63%) were less active during pursuit maintenance in a combined volitional and reflexive pursuit task than during purely volitional pursuit. Interestingly and surprisingly, the neuronal response to the addition of the large-field motion was highly correlated with the neuronal response to a target blink. This suggests that FEFsem neuronal responses to these different perturbations-whether the addition or subtraction of retinal input-may be related. We conjecture that these findings are due to changing weights of both the volitional and reflexive pathways, as well as retinal and extraretinal signals.

Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability.

Science.gov (United States)

Sasaki, Au; Hasegawa, Naoya; Adachi, Kazunori; Sakagami, Hiroshi; Suda, Naoto

2017-10-01

The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; morphological features (e.g., osteoclast genesis and tooth movement) were also evaluated. To clarify the underlying mechanism of orthodontic treatment-induced alteration of orofacial motor excitability, analgesics were administrated for 1 day. At D1 and D3, orthodontic treatment significantly decreased the threshold for inducing the jaw-opening reflex but significantly increased the threshold at D7. Other parameters of the jaw-opening reflex were also evaluated (e.g., latency, duration and area under the curve of anterior digastric muscles activity), and only the latency of the D1 group was significantly different from that of the other groups. Temporal alteration of the jaw-opening reflex excitability was significantly correlated with changes in morphological features. Aspirin (300 mg·kg -1 ·day -1 ) significantly increased the threshold for inducing the jaw-opening reflex, whereas a lower dose (75-150 mg·kg -1 ·day -1 ) of aspirin or acetaminophen (300 mg·kg -1 ·day -1 ) failed to alter the jaw-opening reflex excitability. These results suggest that an increase of the jaw-opening reflex excitability can be induced acutely by orthodontic treatment, possibly through the cyclooxygenase activation. NEW & NOTEWORTHY It is well known that motor function is affected by pain, but the effect of orthodontic treatment-related pain on the trigeminal

Reflexivity as a control factor of personal coping behavior

OpenAIRE

BEKHTER A.A.

2014-01-01

The article deals with the issue of coping behavior control. The author defines the criteria, levels and aspects of reflexivity within the framework of personal coping behavior. In conclusion the author describes the key facets of coping behavior control and how reflexivity affects them.

Isometric and Dynamic Control of Neck Muscles : Reflexive contributions and muscle synergies

NARCIS (Netherlands)

De Bruijn, E.

2014-01-01

It is well established that the central nervous system (CNS) stabilizes the head using reflexive feedback and cocontraction. The major reflexive pathways in the neck are through muscle spindles generating the cervicocollic reflex (CCR) and through the vestibular organ generating the vestibulocollic

A Japanese Stretching Intervention Can Modify Lumbar Lordosis Curvature.

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Kadono, Norio; Tsuchiya, Kazushi; Uematsu, Azusa; Kamoshita, Hiroshi; Kiryu, Kazunori; Hortobágyi, Tibor; Suzuki, Shuji

2017-08-01

Eighteen healthy male adults were assigned to either an intervention or control group. Isogai dynamic therapy (IDT) is one of Japanese stretching interventions and has been practiced for over 70 years. However, its scientific quantitative evidence remains unestablished. The objective of this study was to determine whether IDT could modify lumbar curvature in healthy young adults compared with stretching exercises used currently in clinical practice. None of previous studies have provided data that conventional stretching interventions could modify spinal curvatures. However, this study provides the first evidence that a specific form of a Japanese stretching intervention can acutely modify the spinal curvatures. We compared the effects of IDT, a Japanese stretching intervention (n=9 males), with a conventional stretching routine (n=9 males) used widely in clinics to modify pelvic tilt and lumbar lordosis (LL) angle. We measured thoracic kyphosis (TK) and LL angles 3 times during erect standing using the Spinal Mouse before and after each intervention. IDT consisted of: (1) hip joint correction, (2) pelvic tilt correction, (3) lumbar alignment correction, and (4) squat exercise stretch. The control group performed hamstring stretches while (1) standing and (2) sitting. IDT increased LL angle to 25.1 degrees (±5.9) from 21.2 degrees (±6.9) (P=0.047) without changing TK angle (pretest: 36.8 degrees [±6.9]; posttest: 36.1 degrees [±6.5]) (P=0.572). The control group showed no changes in TK (P=0.819) and LL angles (P=0.744). IDT can thus be effective for increasing LL angle, hence anterior pelvic tilt. Such modifications could ameliorate low back pain and improve mobility in old adults with an unfavorable pelvic position.

The influence of stretching on tensile strength and solubility of poly(vinyl alcohol) fibres

NARCIS (Netherlands)

Heikens, D.; Bleijenberg, A.C.A.M.; Hoppenbrouwers, J.J.M.; Barentsen, W.M.

1971-01-01

The strength of wet-spun poly(vinyl alcohol) (pva) fibres is given as function of bath-stretching, wet-stretching and hot-stretching. In the two equations derived for strength of wet-stretching and hot-stretching the complex influence of the bath-stretching and hot-stretching is demonstrated. The

Mechanical stretching effect on the actuator performance of cellulose electroactive paper

International Nuclear Information System (INIS)

Kim, Jung-Hwan; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

2009-01-01

The mechanical stretching effect on the actuating performance of electroactive cellulose paper (EAPap) was studied. A lattice elongation of cellulose fibrils due to in-plane tensile stress along the stretching direction was observed by the x-ray diffraction method. The shrinkage of the fibril diameter as a function of stretching ratio was confirmed by surface and cross-sectional images. While the actuator performance in terms of bending displacement decreased as the stretching ratio increased, the resonance frequency linearly increased as the stretching ratio increased, which was compared with the theoretical frequency data found from a cantilever beam model. The actuator efficiency was evaluated from the electrical input power consumption and the mechanical output power of an EAPap actuator. It was revealed that the stretching process increased the electro-mechanical efficiency of the EAPap actuator. The mechanism of the influence of the stretching effect on the performance of an EAPap actuator is discussed

Spontaneous bending of pre-stretched bilayers.

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DeSimone, Antonio

2018-01-01

We discuss spontaneously bent configurations of pre-stretched bilayer sheets that can be obtained by tuning the pre-stretches in the two layers. The two-dimensional nonlinear plate model we use for this purpose is an adaptation of the one recently obtained for thin sheets of nematic elastomers, by means of a rigorous dimensional reduction argument based on the theory of Gamma-convergence (Agostiniani and DeSimone in Meccanica. doi:10.1007/s11012-017-0630-4, 2017, Math Mech Solids. doi:10.1177/1081286517699991, arXiv:1509.07003, 2017). We argue that pre-stretched bilayer sheets provide us with an interesting model system to study shape programming and morphing of surfaces in other, more complex systems, where spontaneous deformations are induced by swelling due to the absorption of a liquid, phase transformations, thermal or electro-magnetic stimuli. These include bio-mimetic structures inspired by biological systems from both the plant and the animal kingdoms.

Optofluidic time-stretch quantitative phase microscopy.

Science.gov (United States)

Guo, Baoshan; Lei, Cheng; Wu, Yi; Kobayashi, Hirofumi; Ito, Takuro; Yalikun, Yaxiaer; Lee, Sangwook; Isozaki, Akihiro; Li, Ming; Jiang, Yiyue; Yasumoto, Atsushi; Di Carlo, Dino; Tanaka, Yo; Yatomi, Yutaka; Ozeki, Yasuyuki; Goda, Keisuke

2018-03-01

Innovations in optical microscopy have opened new windows onto scientific research, industrial quality control, and medical practice over the last few decades. One of such innovations is optofluidic time-stretch quantitative phase microscopy - an emerging method for high-throughput quantitative phase imaging that builds on the interference between temporally stretched signal and reference pulses by using dispersive properties of light in both spatial and temporal domains in an interferometric configuration on a microfluidic platform. It achieves the continuous acquisition of both intensity and phase images with a high throughput of more than 10,000 particles or cells per second by overcoming speed limitations that exist in conventional quantitative phase imaging methods. Applications enabled by such capabilities are versatile and include characterization of cancer cells and microalgal cultures. In this paper, we review the principles and applications of optofluidic time-stretch quantitative phase microscopy and discuss its future perspective. Copyright © 2017 Elsevier Inc. All rights reserved.

ESO Reflex: a graphical workflow engine for data reduction

Science.gov (United States)

Hook, Richard; Ullgrén, Marko; Romaniello, Martino; Maisala, Sami; Oittinen, Tero; Solin, Otto; Savolainen, Ville; Järveläinen, Pekka; Tyynelä, Jani; Péron, Michèle; Ballester, Pascal; Gabasch, Armin; Izzo, Carlo

ESO Reflex is a prototype software tool that provides a novel approach to astronomical data reduction by integrating a modern graphical workflow system (Taverna) with existing legacy data reduction algorithms. Most of the raw data produced by instruments at the ESO Very Large Telescope (VLT) in Chile are reduced using recipes. These are compiled C applications following an ESO standard and utilising routines provided by the Common Pipeline Library (CPL). Currently these are run in batch mode as part of the data flow system to generate the input to the ESO/VLT quality control process and are also exported for use offline. ESO Reflex can invoke CPL-based recipes in a flexible way through a general purpose graphical interface. ESO Reflex is based on the Taverna system that was originally developed within the UK life-sciences community. Workflows have been created so far for three VLT/VLTI instruments, and the GUI allows the user to make changes to these or create workflows of their own. Python scripts or IDL procedures can be easily brought into workflows and a variety of visualisation and display options, including custom product inspection and validation steps, are available. Taverna is intended for use with web services and experiments using ESO Reflex to access Virtual Observatory web services have been successfully performed. ESO Reflex is the main product developed by Sampo, a project led by ESO and conducted by a software development team from Finland as an in-kind contribution to joining ESO. The goal was to look into the needs of the ESO community in the area of data reduction environments and to create pilot software products that illustrate critical steps along the road to a new system. Sampo concluded early in 2008. This contribution will describe ESO Reflex and show several examples of its use both locally and using Virtual Observatory remote web services. ESO Reflex is expected to be released to the community in early 2009.

A comparison of five elicitation techniques for elicitation of attributes of low involvement products

DEFF Research Database (Denmark)

Bech-Larsen, Tino; Nielsen, Niels Asger

1999-01-01

of dimensions directed from theories of consumer buying behaviour. Although a number of differences between the techniques are identified in the study, the main findings are that the robustness of the different techniques for attribute elicitation is considerable Udgivelsesdato: JUN......The critical first step for most instruments used in analysing consumer choice and motivation is the identification of product attributes which are important to the consumer and for which there are differences among the available product alternatives. A number of techniques, ranging from...... the complex elicitation of idiosyncratic attributes or simpler picking procedures, has been developed to elicitate such attributes. The purpose of the study presented here is to com-pare attributes of a low involvement product, viz. vegetable oil, elicited by five different techniques on a number...

Reflex epilepsy: a review

Directory of Open Access Journals (Sweden)

Karim Nikkhah

2017-01-01

Full Text Available Interesting phenomena of reflex epileptic syndromes are characterized by epileptic seizures each one induced by specific stimulus with a variety of types. Simple triggers, which lead to seizures within seconds, are of sensory type (most commonly visual, most rarely tactile or proprioceptive stimuli. Complex triggers, which are mostly of cognitive type such as praxis, reading, talking, and music, usually induce the epileptic event within minutes. It should differ from what most epileptic patients report as provocative precipitants for seizures (such as emotional stress, fatigue, fever, sleep deprivation, alcohol, and menstrual cycle. The identification of a specific trigger is not only important for patients or their parents to avoid seizures, but also it might help neurologists to choose the most effective antiepileptic drug for each case. In addition, research in this area may possibly reveal some underlying pathophysiology of epileptic phenomena in the brain.In this review, we briefly introduce reported reflex epileptic seizures, their clinical features and management.

Reflexive Dressing: Rethinking Retro

Directory of Open Access Journals (Sweden)

Stella North

2016-03-01

Full Text Available This article undertakes a philosophical exploration of the act we know, or think we know, as ‘dressing’. Inhabiting, in thought, the moment in which we dress, I examine some of its constituent mechanisms, attending to the impulses by which dressing is generated out of subjective experience.  When those impulses are temporally marked, as they are in the case of retro dress, this generation is a two-pronged process, in which the holding of the body in time, and the holding of time in the body, recalibrate one another. The process of ‘dressing,’ in this understanding, has a reflexivity which is double; it entails the turning of the body, with dress as medium, towards itself, and the turning of present experience towards some felt notion of the past. Reflexively dressing, we are always becoming ourselves, and becoming other than ourselves, at once; a movement of circuitous internalisation and externalisation by which the ambiguation inherent in material experience is realised.

ACUTE EFFECTS OF THREE DIFFERENT STRETCHING PROTOCOLS ON THE WINGATE TEST PERFORMANCE

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Bruno L. Franco

2012-03-01

Full Text Available The purpose of this study was to examine the acute effects of different stretching exercises on the performance of the traditional Wingate test (WT. Fifteen male participants performed five WT; one for familiarization (FT, and the remaining four after no stretching (NS, static stretching (SS, dynamic stretching (DS, and proprioceptive neuromuscular facilitation (PNF. Stretches were targeted for the hamstrings, quadriceps, and calf muscles. Peak power (PP, mean power (MP, and the time to reach PP (TP were calculated. The MP was significantly lower when comparing the DS (7.7 ± 0.9 W/kg to the PNF (7.3 ± 0.9 W/kg condition (p < 0.05. For PP, significant differences were observed between more comparisons, with PNF stretching providing the lowest result. A consistent increase of TP was observed after all stretching exercises when compared to NS. The results suggest the type of stretching, or no stretching, should be considered by those who seek higher performance and practice sports that use maximal anaerobic power.

Reflexive anaphor resolution in spoken language comprehension: Structural constraints and beyond

Directory of Open Access Journals (Sweden)

Kaili eClackson

2014-08-01

Full Text Available We report results from an eye-tracking during listening study examining English-speaking adults’ online processing of reflexive pronouns, and specifically whether the search for an antecedent is restricted to syntactically appropriate positions. Participants listened to a short story where the recipient of an object was introduced with a reflexive, and were asked to identify the object recipient as quickly as possible. This allowed for the recording of participants’ offline interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our offline results show that the ultimate interpretation for reflexives was constrained by binding principles, the response time and eye-movement data revealed that during processing participants were temporarily distracted by a structurally inappropriate competitor antecedent when this was prominent in the discourse. These results indicate that in addition to binding principles, online referential decisions are also affected by discourse-level information.

Reflexive anaphor resolution in spoken language comprehension: structural constraints and beyond

Science.gov (United States)

Clackson, Kaili; Heyer, Vera

2014-01-01

We report results from an eye-tracking during listening study examining English-speaking adults’ online processing of reflexive pronouns, and specifically whether the search for an antecedent is restricted to syntactically appropriate positions. Participants listened to a short story where the recipient of an object was introduced with a reflexive, and were asked to identify the object recipient as quickly as possible. This allowed for the recording of participants’ offline interpretation of the reflexive, response times, and eye movements on hearing the reflexive. Whilst our offline results show that the ultimate interpretation for reflexives was constrained by binding principles, the response time, and eye-movement data revealed that during processing participants were temporarily distracted by a structurally inappropriate competitor antecedent when this was prominent in the discourse. These results indicate that in addition to binding principles, online referential decisions are also affected by discourse-level information. PMID:25191290

Management of Reflex Anoxic Seizures

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J Gordon Millichap

2013-10-01

Full Text Available Investigators at the Roald Dahl EEG Unit, Alder Hey Children’s NHS Foundation, Liverpool, UK, review the definition, pathophysiology, clinical presentation, and management of reflex anoxic seizures (RAS in children.

Eliminating electromechanical instability in dielectric elastomers by employing pre-stretch

International Nuclear Information System (INIS)

Jiang, Liang; Jerrams, Stephen; Betts, Anthony; Kennedy, David

2016-01-01

Electromechanical instability (EMI) is one of most common failure modes for dielectric elastomers (DEs). It has been reported that pre-stretching a DE sample can suppress EMI due to strain stiffening taking place for larger strains and a higher elastic modulus are achieved at high stretch ratios when a voltage is applied to the material. In this work, the influence of equi-biaxial stretch on DE secant modulus was studied using VHB 4910 and silicone rubber (SR) composites containing barium titanate (BaTiO 3 , BT) particles and also dopamine coated BT (DP-BT) particles. The investigation of equi-biaxial deformation and EMI failure for VHB 4910 was undertaken by introducing a voltage-stretch function. The results showed that EMI was suppressed by equi-biaxial pre-stretch for all the DEs fabricated and tested. The stiffening properties of the DE materials were also studied with respect to the secant modulus. Furthermore, a voltage-induced strain of above 200% was achieved for the polyacrylate film by applying a pre-stretch ratio of 2.0 without EMI occurring. However, a maximum voltage-induced strain in the polyacrylate film of 78% was obtained by the SR/20 wt% DP-BT composite for a lower applied pre-stretch ratio of 1.6 and again EMI was eliminated. (paper)

Linear time delay methods and stability analyses of the human spine. Effects of neuromuscular reflex response.

Science.gov (United States)

Franklin, Timothy C; Granata, Kevin P; Madigan, Michael L; Hendricks, Scott L

2008-08-01

Linear stability methods were applied to a biomechanical model of the human musculoskeletal spine to investigate effects of reflex gain and reflex delay on stability. Equations of motion represented a dynamic 18 degrees-of-freedom rigid-body model with time-delayed reflexes. Optimal muscle activation levels were identified by minimizing metabolic power with the constraints of equilibrium and stability with zero reflex time delay. Muscle activation levels and associated muscle forces were used to find the delay margin, i.e., the maximum reflex delay for which the system was stable. Results demonstrated that stiffness due to antagonistic co-contraction necessary for stability declined with increased proportional reflex gain. Reflex delay limited the maximum acceptable proportional reflex gain, i.e., long reflex delay required smaller maximum reflex gain to avoid instability. As differential reflex gain increased, there was a small increase in acceptable reflex delay. However, differential reflex gain with values near intrinsic damping caused the delay margin to approach zero. Forward-dynamic simulations of the fully nonlinear time-delayed system verified the linear results. The linear methods accurately found the delay margin below which the nonlinear system was asymptotically stable. These methods may aid future investigations in the role of reflexes in musculoskeletal stability.

Effects of Static Stretching and Playing Soccer on Knee Laxity.

Science.gov (United States)

Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W; Freiwald, Jürgen

2015-11-01

This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Randomized controlled trial. University biomechanics laboratory. Thirty-one athletes were randomly assigned into a stretching (26.9 ± 6.2 years, 1.77 ± 0.09 m, 67.9 ± 10.7 kg) and a control group (27.9 ± 7.4 years, 1.75 ± 0.08 m, 72.0 ± 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 ± 5.6 years, 1.74 ± 0.10 m, 71.8 ± 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury. The stretching group performed 4 different static stretching exercises with a duration of 2 × 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes. Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention. There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 ± 1.6 mm (P soccer of 1.0 ± 1.5 mm (P = 0.001). The ATT increase after static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups. Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer. The observed increase in ATT after static stretching and playing soccer may be associated with changes in kinesthetic perception and sensorimotor control, activation of muscles, joint stability, overall performance, and higher injury risk.

Acute effect of different stretching methods on isometric muscle strength

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Gabriel Vasconcellos de Lima Costa e Silva

2014-03-01

This study investigated the acute effect of static stretching methods (SS and proprioceptive neuromuscular facilitation (PNF on the static muscle strength (SMS. Eleven young male subjects with strength training experience, performed 3 tests with a 48h interval between them, randomly selected, where each one subject carried out all procedures: a hand grip without stretching; b hand grip preceded by static stretching of wrist flexors muscles; c hand grip preceded by PNF stretching of wrist flexors muscles. The Shapiro-Wilk test verified the normality of data, and a one-way ANOVA with repeated measures, followed by Tukey’s post hoc test, evaluated the differences between the groups. The significance was set at p 0.05. In conclusion, both stretching methods had caused negative effects on isometric strength, reducing its levels.

A new hypothesis of cause of syncope: trigeminocardiac reflex during extraction of teeth.

Science.gov (United States)

Arakeri, Gururaj; Arali, Veena

2010-02-01

Transient Loss Of Consciousness (TLOC) or vasovagal syncope is well known phenomenon in dental/maxillofacial surgery. Despite considerable study of vasovagal syncope, its pathophysiology remains to be fully elucidated. After having encountered a case of trigeminocardiac reflex after extraction of maxillary first molar we observed and studied 400 extractions under local anesthesia to know the relation between trigeminocardiac reflex and syncope. We make hypothesis that trigeminocardiac reflex which is usually seen under general anesthesia when all sympathetic reflexes are blunted can also occur under local anesthesia during extractions of maxillary molars (dento-cardiac reflex) and mediate syncope.

Upper Limb Static-Stretching Protocol Decreases Maximal Concentric Jump Performance

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Paulo H. Marchetti

2014-12-01

Full Text Available The purpose of the present study was to evaluate the acute effects of an upper limb static-stretching (SS protocol on the maximal concentric jump performance. We recruited 25 young healthy, male, resistance trained individuals (stretched group, n = 15 and control group, n = 10 in this study. The randomized between group experimental protocol consisted of a three trials of maximal concentric jump task, before and after a SS of the upper limb. Vertical ground reaction forces (vGRF and surface electromyography (sEMG of both gastrocnemius lateralis (GL and vastus lateralis (VL were acquired. An extensive SS was employed consisting of ten stretches of 30 seconds, with 15 seconds of rest, and 70-90% of the point of discomfort (POD. ANOVA (2x2 (group x condition was used for shoulder joint range of motion (ROM, vGRF and sEMG. A significant interaction for passive ROM of the shoulder joint revealed significant increases between pre- and post-SS protocol (p < 0.001. A significant interaction demonstrated decreased peak force and an increased peak propulsion duration between pre- and post-stretching only for stretch group (p = 0.021, and p = 0.024, respectively. There was a significant main effect between groups (stretch and control for peak force for control group (p = 0.045. Regarding sEMG variables, there were no significant differences between groups (control versus stretched or condition (pre-stretching versus post-stretching for the peak amplitude of RMS and IEMG for both muscles (VL and GL. In conclusion, an acute extensive SS can increase the shoulder ROM, and negatively affect both the propulsion duration and peak force of the maximal concentric jump, without providing significant changes in muscle activation.

Cyclic Stretch Alters Vascular Reactivity of Mouse Aortic Segments

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Arthur Leloup

2017-10-01

Full Text Available Large, elastic arteries buffer the pressure wave originating in the left ventricle and are constantly exposed to higher amplitudes of cyclic stretch (10% than muscular arteries (2%. As a crucial factor for endothelial and smooth muscle cell function, cyclic stretch has, however, never been studied in ex vivo aortic segments of mice. To investigate the effects of cyclic stretch on vaso-reactivity of mouse aortic segments, we used the Rodent Oscillatory Tension Set-up to study Arterial Compliance (ROTSAC. The aortic segments were clamped at frequencies of 6–600 bpm between two variable preloads, thereby mimicking dilation as upon left ventricular systole and recoiling as during diastole. The preloads corresponding to different transmural pressures were chosen to correspond to a low, normal or high amplitude of cyclic stretch. At different time intervals, cyclic stretch was interrupted, the segments were afterloaded and isometric contractions by α1-adrenergic stimulation with 2 μM phenylephrine in the absence and presence of 300 μM L-NAME (eNOS inhibitor and/or 35 μM diltiazem (blocker of voltage-gated Ca2+ channels were measured. As compared with static or cyclic stretch at low amplitude (<10 mN or low frequency (0.1 Hz, cyclic stretch at physiological amplitude (>10 mN and frequency (1–10 Hz caused better ex vivo conservation of basal NO release with time after mounting. The relaxation of PE-precontracted segments by addition of ACh to stimulate NO release was unaffected by cyclic stretch. In the absence of basal NO release (hence, presence of L-NAME, physiological in comparison with aberrant cyclic stretch decreased the baseline tension, attenuated the phasic contraction by phenylephrine in the absence of extracellular Ca2+ and shifted the smaller tonic contraction more from a voltage-gated Ca2+ channel-mediated to a non-selective cation channel-mediated. Data highlight the need of sufficient mechanical activation of endothelial and

Guidelines for Stretch Flanging Advanced High Strength Steels

International Nuclear Information System (INIS)

Sriram, S.; Chintamani, J.

2005-01-01

Advanced High Strength Steels (AHSS) are currently being considered for use in closure and structural panels in the automotive industry because of their high potential for affordable weight reduction and improved performance. AHSS such as dual phase steels are currently being used in some vehicle platforms. From a manufacturing perspective, stretch flanging during stamping is an important deformation mode requiring careful consideration of geometry and the die process. This paper presents some geometric and process guidelines for stretch flanging AHSS. Hole expansion experiments were conducted to determine the failure limit for a sheared edge condition. Effects of punching clearance, prestrain and prior strain path on hole expansion were explored in these experiments. In addition, dynamic explicit FE calculations using LS-DYNA were also conducted for a typical stretch flange by varying some key geometric parameters. The experimental and FEA results were then analyzed to yield process and geometric guidelines to enable successful stretch flanging of AHSS

High-power ion beam generation with an inverse reflex tetrode

International Nuclear Information System (INIS)

Pasour, J.A.; Mahaffey, R.A.; Golden, J.; Kapetanakos, C.A.

1980-01-01

A new reflexing-electron ion source is described. The device produces a unidirectional ion beam with relatively high efficiency even when the applied magnetic field exceeds the self-field. This new source operates at a low, constant impedance during much of the applied voltage pulse and is better matched to available high-power, low-impedance generators than previous reflexing-electron devices. Proton pulses with peak current approx.500 kA have been produced with the inverse reflex tetrode coupled to the Gamble II generator

The Role of Transformational Leadership in Enhancing Team Reflexivity

NARCIS (Netherlands)

M.C. Schippers (Michaéla); D.N. den Hartog (Deanne); P.L. Koopman (Paul); D.L. van Knippenberg (Daan)

2007-01-01

textabstractTeam reflexivity, or the extent to which teams reflect upon and modify their functioning, has been identified as a key factor in the effectiveness of work teams. As yet, however, little is known about the factors that play a role in enhancing team reflexivity, and it is thus important to

The role of transformational leadership in enhancing team reflexivity

NARCIS (Netherlands)

Schippers, M.C.; den Hartog, D.N.; Koopman, P.L.; van Knippenberg, D.

2008-01-01

Team reflexivity, or the extent to which teams reflect upon and modify their functioning, has been identified as a key factor in the effectiveness of work teams. As yet, however, little is known about the factors that play a role in enhancing team reflexivity, and it is thus important to develop

Stretching skeletal muscle: chronic muscle lengthening through sarcomerogenesis.

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Alexander M Zöllner

Full Text Available Skeletal muscle responds to passive overstretch through sarcomerogenesis, the creation and serial deposition of new sarcomere units. Sarcomerogenesis is critical to muscle function: It gradually re-positions the muscle back into its optimal operating regime. Animal models of immobilization, limb lengthening, and tendon transfer have provided significant insight into muscle adaptation in vivo. Yet, to date, there is no mathematical model that allows us to predict how skeletal muscle adapts to mechanical stretch in silico. Here we propose a novel mechanistic model for chronic longitudinal muscle growth in response to passive mechanical stretch. We characterize growth through a single scalar-valued internal variable, the serial sarcomere number. Sarcomerogenesis, the evolution of this variable, is driven by the elastic mechanical stretch. To analyze realistic three-dimensional muscle geometries, we embed our model into a nonlinear finite element framework. In a chronic limb lengthening study with a muscle stretch of 1.14, the model predicts an acute sarcomere lengthening from 3.09[Formula: see text]m to 3.51[Formula: see text]m, and a chronic gradual return to the initial sarcomere length within two weeks. Compared to the experiment, the acute model error was 0.00% by design of the model; the chronic model error was 2.13%, which lies within the rage of the experimental standard deviation. Our model explains, from a mechanistic point of view, why gradual multi-step muscle lengthening is less invasive than single-step lengthening. It also explains regional variations in sarcomere length, shorter close to and longer away from the muscle-tendon interface. Once calibrated with a richer data set, our model may help surgeons to prevent muscle overstretch and make informed decisions about optimal stretch increments, stretch timing, and stretch amplitudes. We anticipate our study to open new avenues in orthopedic and reconstructive surgery and enhance

Static versus dynamic stretching: Chronic and acute effects on Agility performance in male athletes

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Iman Taleb-Beydokhti

2015-04-01

Full Text Available The purpose of this study was to examine the acute and chronic effects of static & dynamic stretching protocols on agility performance in amateur handball players. Twelve male amateur handball players (age: 19.66 ± 4.02 years old, weight: 67.12 ± 8.73 kg, height: 178.29 ± 7.81 cm participated in this study. The athletes were randomly allocated into two groups: static stretching or dynamic stretching. All of them underwent an initial evaluation and were submitted to the first intervention. They were evaluated once again and at the end of 12 training sessions. The results analyzed using ANOVA showed that there was a significant decrease in agility time after dynamic stretching against no stretching in the acute phase; but, there were no significant differences between dynamic stretching and no stretching in the chronic phase. In addition, there was no a significant difference between no stretching and static stretching in the acute phase; while, There was a significant decrease in agility time after no stretching against static stretching in the chronic phase. It was concluded that acute dynamic stretching as part of a warm-up may decrease agility time performance, whereas static stretching seems to increase agility time performance. Consequently, the acute and chronic static stretching should not be performed prior to an explosive athletic performance. Keywords: Handball, Agility, Dynamic stretching, Static stretching

Deprivation and Recovery of Sleep in Succession Enhances Reflexive Motor Behavior

OpenAIRE

Sprenger, Andreas; Weber, Frederik D.; Machner, Bjoern; Talamo, Silke; Scheffelmeier, Sabine; Bethke, Judith; Helmchen, Christoph; Gais, Steffen; Kimmig, Hubert; Born, Jan

2015-01-01

Sleep deprivation impairs inhibitory control over reflexive behavior, and this impairment is commonly assumed to dissipate after recovery sleep. Contrary to this belief, here we show that fast reflexive behaviors, when practiced during sleep deprivation, is consolidated across recovery sleep and, thereby, becomes preserved. As a model for the study of sleep effects on prefrontal cortex-mediated inhibitory control in humans, we examined reflexive saccadic eye movements (express saccades), as w...

Trigeminocardiac reflex during endoscopic juvenile nasopharyngeal angiofibroma surgery: an appraisal.

Science.gov (United States)

Sharma, Shilpee Bhatia; Janakiram, Trichy Narayanan; Baxi, Hina; Chinnasamy, Balamurugan

2017-07-01

Juvenile nasopharyngeal angiofibroma is a locally aggressive benign tumour which has propensity to erode the skull base. The tumour spreads along the pathways of least resistance and is in close proximity to the extracranial part of trigeminal nerve. Advancements in expanded approaches for endoscopic excision of tumours in infratemporal fossa and pterygopalatine fossa increase the vulnerability for the trigeminocardiac reflex. The manipulation of nerve and its branches during tumour dissection can lead to sensory stimulation and thus inciting the reflex. The aim of our study is to report the occurrence of trigeminocardiac reflex in endoscopic excision of juvenile nasopharyngeal angiofibroma. To describe the occurence of trigeminocardiac reflex during endoscopic endonasal excision of juvenile nasopharyngeal angiofibroma. We studied the occurrence of TCR in 15 patients (out of 242 primary cases and 52 revision cases) operated for endoscopic endonasal excision of JNA. The drop in mean arterial blood pressure and heart rate were observed and measured. To the best of our knowledge of English literature, this is the first case series reporting TCR as complication in endoscopic excision of JNA. occurence of this reflex has been mentioned in various occular, maxillofacial surgeries but its occurence during endoscopic excision of JNA has never been reported before. Manifestation of trigeminocardiac reflex during surgery can alter the course of the surgery and is a potential threat to life. It is essential for the anesthetist and surgeons to be familiar with the presentations, preventive measures and management protocols.

Filament stretching rheometer: inertia compensation revisited

DEFF Research Database (Denmark)

Szabo, Peter; McKinley, Gareth H.

2003-01-01

The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end of the e......The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end...

New insights into the pathophysiology of post-stroke spasticity

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Sheng eLi

2015-04-01

Full Text Available Spasticity is one of many consequences after stroke. It is characterized by a velocity-dependent increase in resistance during passive stretch, resulting from hyperexcitability of the stretch reflex. The underlying mechanism of the hyperexcitable stretch reflex, however, remains poorly understood. Accumulated experimental evidence has supported supraspinal origins of spasticity, likely from an imbalance between descending inhibitory and facilitatory regulation of spinal stretch reflexes secondary to cortical disinhibition after stroke. The excitability of reticulospinal and vestibulospinal tracts has been assessed in stroke survivors with spasticity using non-invasive indirect measures. There are strong experimental findings that support the reticulospinal hyperexcitability as a prominent underlying mechanism of post-stroke spasticity. This mechanism can at least partly account for clinical features associated with spasticity and provide insightful guidance for clinical assessment and management of spasticity. However, the possible role of VST hyperexcitability can not be ruled out from indirect measures. In vivo measure of individual brainstem nuclei in stroke survivors with spasticity using advanced fMRI techniques in the future is probably able to provide direct evidence of pathogenesis of post-stroke spasticity.

New insights into the pathophysiology of post-stroke spasticity.

Science.gov (United States)

Li, Sheng; Francisco, Gerard E

2015-01-01

Spasticity is one of many consequences after stroke. It is characterized by a velocity-dependent increase in resistance during passive stretch, resulting from hyperexcitability of the stretch reflex. The underlying mechanism of the hyperexcitable stretch reflex, however, remains poorly understood. Accumulated experimental evidence has supported supraspinal origins of spasticity, likely from an imbalance between descending inhibitory and facilitatory regulation of spinal stretch reflexes secondary to cortical disinhibition after stroke. The excitability of reticulospinal (RST) and vestibulospinal tracts (VSTs) has been assessed in stroke survivors with spasticity using non-invasive indirect measures. There are strong experimental findings that support the RST hyperexcitability as a prominent underlying mechanism of post-stroke spasticity. This mechanism can at least partly account for clinical features associated with spasticity and provide insightful guidance for clinical assessment and management of spasticity. However, the possible role of VST hyperexcitability cannot be ruled out from indirect measures. In vivo measure of individual brainstem nuclei in stroke survivors with spasticity using advanced fMRI techniques in the future is probably able to provide direct evidence of pathogenesis of post-stroke spasticity.

Requirements Elicitation Problems: A Literature Analysis

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Bill Davey

2015-06-01

Full Text Available Requirements elicitation is the process through which analysts determine the software requirements of stakeholders. Requirements elicitation is seldom well done, and an inaccurate or incomplete understanding of user requirements has led to the downfall of many software projects. This paper proposes a classification of problem types that occur in requirements elicitation. The classification has been derived from a literature analysis. Papers reporting on techniques for improving requirements elicitation practice were examined for the problem the technique was designed to address. In each classification the most recent or prominent techniques for ameliorating the problems are presented. The classification allows the requirements engineer to be sensitive to problems as they arise and the educator to structure delivery of requirements elicitation training.

Belief Elicitation in Experiments

DEFF Research Database (Denmark)

Blanco, Mariana; Engelmann, Dirk; Koch, Alexander

Belief elicitation in economics experiments usually relies on paying subjects according to the accuracy of stated beliefs in addition to payments for other decisions. Such incentives, however, allow risk-averse subjects to hedge with their stated beliefs against adverse outcomes of other decisions......-belief elicitation treatment using a financial investment frame, where hedging arguably would be most natural....

Understanding hospital meal experiences by means of participant-driven-photo-elicitation.

Science.gov (United States)

Justesen, Lise; Mikkelsen, Bent E; Gyimóthy, Szilvia

2014-04-01

A patients' hospital meal experiences can be complex and often difficult to capture using traditional methods. This study investigated patients' hospital meal experiences using participant-driven-photo-elicitation (PDPE). PDPE invites respondents to photograph their daily lives and combines this with interviews, which can provide deeper insight into multisensory experiences beyond verbal or written discourse. The sample consisted of eight hospitalised patients. Patients completed a photo-essay of their hospital meal experience during a single day at a Danish hospital and afterwards participated in an open-ended interview. Two inductive analytical approaches were selected to assess the patients' reflections on their hospital meal experiences. First, the interview transcripts were analysed using the Semiotic Analysis approach using qualitative data analysis software NVivo 9. Second, the 91 produced photographs and the participants' engagement with the photographs were analysed by means of a Reflexive Content Analysis. The study found that PDPE is a research method that can be used for expanding the conceptualisation of hospital meal experiences, revealing the significance of the meal context, materiality and memories beyond food per se. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stretching single fibrin fibers hampers their lysis.

Science.gov (United States)

Li, Wei; Lucioni, Tomas; Li, Rongzhong; Bonin, Keith; Cho, Samuel S; Guthold, Martin

2017-09-15

Blood clots, whose main structural component is a mesh of microscopic fibrin fibers, experience mechanical strain from blood flow, clot retraction and interactions with platelets and other cells. We developed a transparent, striated and highly stretchable substrate made from fugitive glue (a styrenic block copolymer) to investigate how mechanical strain affects lysis of single, suspended fibrin fibers. In this suspended fiber assay, lysis manifested itself by fiber elongation, thickening (disassembly), fraying and collapse. Stretching single fibrin fibers significantly hampered their lysis. This effect was seen in uncrosslinked and crosslinked fibers. Crosslinking (without stretching) also hampered single fiber lysis. Our data suggest that strain is a novel mechanosensitive factor that regulates blood clot dissolution (fibrinolysis) at the single fiber level. At the molecular level of single fibrin molecules, strain may distort, or hinder access to, plasmin cleavage sites and thereby hamper lysis. Fibrin fibers are the major structural component of a blood clot. We developed a highly stretchable substrate made from fugitive glue and a suspended fibrin fiber lysis assay to investigate the effect of stretching on single fibrin fibers lysis. The key findings from our experiments are: 1) Fibers thicken and elongate upon lysis; 2) stretching strongly reduces lysis; 3) this effect is more pronounced for uncrosslinked fibers; and 4) stretching fibers has a similar effect on reducing lysis as crosslinking fibers. At the molecular level, strain may distort plasmin cleavage sites, or restrict access to those sites. Our results suggest that strain may be a novel mechanobiological factor that regulates fibrinolysis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

From Incidental, Mechanically-Induced Arrhythmias to Reflex-Defined Arrhythmogenicity: On The Track of The Ternary Reflex System Resemblance to The "Infancy" of New Era or Rediscovery.

Science.gov (United States)

Stirbys, Petras

2016-01-01

The underlying pathophysiology of supraventricular and ventricular arrhythmias remains a matter of intense investigation. Though evolving, the contemporary explanations do not encompass all aspects of arrhythmogenicity. An improved understanding of arrhythmia substrate is needed to augment therapeutic capabilities. Our observation and literature sources demonstrate relatively high incidence of transitory arrhythmias which are non-intentionally generated by the endocardial lead/catheter manipulation. These findings are interesting and potentially may crystallize the reflex-dependent proarrhythmic cardiac activity. Herein we suggest the "reflexogenic arrhythmogenicity" concept extending an overall spectrum of known hypotheses. Cardiovascular reflex action can be categorized into three-tiered levels - intra-cellular, inter-cellular and inter-organic. The first two levels of the triplicate system reside within the cardiac anatomical landmarks (in fact intramurally, intra-organically), however the third one implicates central (cerebral) activity which boomerangs back via centripetal and centrifugal connections. These levels likely compose synoptic ternary reflex set system which may be validated in future studies. To hypothesize, coordinated mutual reciprocity of reflex activity results in stabilization of heart rhythm in robust heart. Any stressful cardiac event may lead to the shift of the rhythm toward unfavorable clinical entity probably via the loss of the influence of dominant reflex. Overall, an interaction and likely intrinsic inter-tiered competition along with possible interplay between physiological and pathological reflexes may be treated as contributing factors for the inception and maintaining of arrhythmias and cardiac performance as well. These assumptions await further documentation. If such a tenet were recognized, the changes in the clinical approach to arrhythmia management might be anticipated, preferably by selective reflex suppression or

Characterizing the stretch-flangeability of hot rolled multiphase steels

International Nuclear Information System (INIS)

Pathak, N.; Butcher, C.; Worswick, M.; Gao, J.

2013-01-01

Hole expansion tests are commonly used to characterize the edge stretching limit of a material. Traditionally, a conical punch is used to expand a punched hole until a through-thickness crack appears. However, many automotive stretch flanging operations involve in-plane edge stretching that is best captured with a flat punch. In this paper, hole expansion tests were carried out on two different hot-rolled multiphase steels using both flat and conical punches. The fracture mechanisms for both punch types were investigated using scanning electron microscopy (SEM)

Enhanced Age Strengthening of Mg-Nd-Zn-Zr Alloy via Pre-Stretching

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Erjun Guo

2016-08-01

Full Text Available Pre-stretching was carried out to modify the microstructure of Mg-Nd-Zn-Zr alloy to enhance its age strengthening. The results indicated that more heterogeneous nucleation sites can be provided by the high density of dislocations caused by the plastic pre-stretching deformation, as well as speeding up the growth rate of precipitates. Comparison of microstructure in non-pre-stretched specimens after artificial aging showed that pre-stretched specimens exhibited a higher number density of precipitates. The fine and coarse plate-shaped precipitates were found in the matrix. Due to an increase in the number density of precipitates, the dislocation slipping during the deformation process is effectively hindered, and the matrix is strengthened. The yield strength stabilizes at 4% pre-stretching condition, and then the evolution is stable within the error bars. The 8% pre-stretched specimens can achieve an ultimate tensile strength of 297 MPa. However, further pre-stretching strains after 8% cannot supply any increase in strength. Tensile fracture surfaces of specimens subjected to pre-stretching strain mainly exhibit a trans-granular cleavage fracture. This work indicated that a small amount of pre-stretching strain can further increase strength of alloy and also effectively enhance the formation of precipitates, which can expand the application fields of this alloy.

Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force

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Leyla Alizadeh Ebadi

2018-03-01

Full Text Available The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles’ isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A 5 min jogging; (B 5 min jogging followed by 15 s static stretching; (C 5 min jogging followed by 30 s static stretching; (D 5 min jogging, followed by static stretching for 45 s. Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

The influence of foot position on stretching of the plantar fascia.

Science.gov (United States)

Flanigan, Ryan M; Nawoczenski, Deborah A; Chen, Linlin; Wu, Hulin; DiGiovanni, Benedict F

2007-07-01

A recent study found nonweightbearing stretching exercises specific to the plantar fascia to be superior to the standard program of weightbearing Achilles tendon-stretching exercises in patients with chronic plantar fasciitis. The present study used a cadaver model to demonstrate the influence of foot and ankle position on stretching of the plantar fascia. Twelve fresh-frozen lower-leg specimens were tested in 15 different configurations representing various combinations of ankle and metatarsophalangeal (MTP) joint dorsiflexion, midtarsal transverse plane abduction and adduction, and forefoot varus and valgus. Measurements were recorded by a differential variable reluctance transducer (DVRT) implanted into the medial band of the plantar fascia, and primary measurement was a percent deformation of the plantar fascia (stretch) with respect to a reference position (90 degrees ankle dorsiflexion, 0 degrees midtarsal and forefoot orientation, and 0 degrees MTP dorsiflexion). Ankle and MTP joint dorsiflexion produced a significant increase (14.91%) in stretch compared to the position of either ankle dorsiflexion alone (9.31% increase, p plantar fascia tissue-specific stretching exercises and lends support to the use of ankle and MTP joint dorsiflexion when employing stretching protocols for nonoperative treatment in patients with chronic proximal plantar fasciitis.

Emotion, reflexivity and social change in the era of extreme fossil fuels.

Science.gov (United States)

Davidson, Debra J

2018-05-09

Reflexivity is an important sociological lens through which to examine the means by which people engage in actions that contribute to social reproduction or social elaboration. Reflexivity theorists have largely overlooked the central place of emotions in reflexive processing, however, thus missing opportunities to enhance our understanding of reflexivity by capitalizing on recent scholarship on emotions emanating from other fields of inquiry. This paper explores the role of emotion in reflexivity, with a qualitative analysis of social responses to hydraulic fracturing in Alberta, Canada, utilizing narrative analysis of long-form interviews with rural landowners who have experienced direct impacts from hydraulic fracturing, and have attempted to voice their concerns in the public sphere. Based on interviews with a selection of two interview participants, the paper highlights the means by which emotions shape reflexivity in consequential ways, beginning with personal and highly individualized emotional responses to contingent situations, which then factor into the social interactions engaged in the pursuit of personal projects. The shared emotional context that emerges then plays a substantial role in shaping outcomes and their implications for social stasis or change. This study exemplifies the extent to which reflexive processing in response to breaches in the social order can be emotionally tumultuous affairs, constituting a significant personal toll that many may be unwilling to pay. © London School of Economics and Political Science 2018.

Affective Modulation of the Startle Eyeblink and Postauricular Reflexes in Autism Spectrum Disorder

Science.gov (United States)

Dichter, Gabriel S.; Benning, Stephen D.; Holtzclaw, Tia N.; Bodfish, James W.

2010-01-01

Eyeblink and postauricular reflexes to standardized affective images were examined in individuals without (n = 37) and with (n = 20) autism spectrum disorders (ASDs). Affective reflex modulation in control participants replicated previous findings. The ASD group, however, showed anomalous reflex modulation patterns, despite similar self-report…

Interset stretching does not influence the kinematic profile of consecutive bench-press sets.

Science.gov (United States)

García-López, David; Izquierdo, Mikel; Rodríguez, Sergio; González-Calvo, Gustavo; Sainz, Nuria; Abadía, Olaia; Herrero, Azael J

2010-05-01

This study was undertaken to examine the role of interset stretching on the time course of acceleration portion AP and mean velocity profile during the concentric phase of 2 bench-press sets with a submaximal load (60% of the 1 repetition maximum). Twenty-five college students carried out, in 3 different days, 2 consecutive bench-press sets leading to failure, performing between sets static stretching, ballistic stretching, or no stretching. Acceleration portion and lifting velocity patterns of the concentric phase were not altered during the second set, regardless of the stretching treatment performed. However, when velocity was expressed in absolute terms, static stretching reduced significantly (p velocity during the second set compared to the first one. Therefore, if maintenance of a high absolute velocity over consecutive sets is important for training-related adaptations, static stretching should be avoided or replaced by ballistic stretching.

Numerical and experimental investigation of stretch-flange forming

International Nuclear Information System (INIS)

Cinotti, N.; Shakeri, H.R.; Worswick, M.J.; Truttmann, S.; Finn, M.J.; Jain, M.; Lloyd, D.J.

2000-01-01

Simulations of stretch flange forming operations are undertaken using explicit dynamic finite element calculations incorporating anisotropic yield criteria. Simple circular stretch flanges utilizing a single circular punch to expand the cut-out were considered. Experiments were performed using 101mm diameter tooling on AA 5754 and AA 5182 aluminum alloy sheets, with varying cut-out and gauge size. Metallurgical aspects of the formability of these aluminum alloys and damage mechanisms were studied. Both optical and Scanning Electron Microscopy (SEM) were used to study ductile fracture behaviour in these materials during the forming operation. The limit strains obtained from the circular stretch flange formability experiments are compared to forming limit diagram (FLD) data from hemispherical dome specimens. (author)

THE CONCEPT OF REFLEXIVE MANAGEMENT OF CONSUMER DEMAND

Directory of Open Access Journals (Sweden)

Maryna Mavrina

2017-11-01

Full Text Available Development of theoretical approaches of demand management is conducted from the moment of awareness of the importance of this concept. Many models of individual consumers were developed. However, to predict the reaction of consumers to the commercial policy of the enterprise, exact methods do not exist yet because the available ones are mostly empirical in nature. Models of behaviour often do not provide the expected result because they use an erroneous approach to the analysis of the mechanism of demand formation. The subject of the research is the theoretical and methodological basis, methods of assessment, and reflexive management of consumer demand of commercial enterprises. The purpose of the paper is developing a concept of reflexive management of consumer demand. To achieve the research goal, the following tasks are set and solved: to substantiate the theoretical and methodological foundations of reflexive consumer management, to analyse existing approaches to the modelling of consumer behaviour; to improve the model of consumer behaviour; to develop a concept of reflexive management of consumer behaviour. Methodology. In the paper, we use such methods and approaches to research as: reflexive approach (phenomenological method, behavioural economic theory, marketing approach, abstract-logical analysis, analysis of theoretical approaches to the modelling of consumer behaviour. Results. Modern approaches to modelling of consumer behaviour are mostly empirical in nature and have shortcomings of general models. In them, there is no description of specific situations of the purchase of goods. They cannot be quantified. Therefore, they cannot be practical models. But they have a weighty advantage in a comprehensive look at motivated purchases, what makes it possible to evaluate the relevance of individual variables and to understand the fundamental processes of consumer behaviour. It makes possible to identify the variables necessary for the

The ubiquitous reflex and its critics in post-revolutionary Russia.

Science.gov (United States)

Sirotkina, Irina

2009-03-01

In the last century, the reflex was more than a scientific concept: it was a cultural idiom that could be used to various aims--political, scholarly, and artistic. In Russia in the 1920s, the reflex became a ubiquitous notion and a current word, part of the revolutionary discourse and, finally, a password to modernity. Two major factors contributed to it: physiological theories of the reflex, widespread in Russia at the early twentieth-century, and the materialist philosophy backed after the Revolution by the Communist party. Everybody who wished to be modern and materialist, in conformity with the official communist views, had to refer to reflexes. Yet, even in this period, the concept was not unproblematic and was criticized by some scientists, philosophers, artists and even Party members. In the paper, I describe both the array of uses of the term and the criticism it received in political, scientific and artistic discourses. It is not uncommon that, taking their origins in culture and common language, scientific concepts later return there in the form of metaphors. Similarly, the reflex was made into a rigorous scientific concept in the nineteenth century but, in the next century, it circulated as a cultural idiom penetrating various areas of political, artistic and academic life.

Stretch activates myosin light chain kinase in arterial smooth muscle

International Nuclear Information System (INIS)

Barany, K.; Rokolya, A.; Barany, M.

1990-01-01

Stretching of porcine carotid arterial muscle increased the phosphorylation of the 20 kDa myosin light chain from 0.23 to 0.68 mol [32P]phosphate/mol light chain, whereas stretching of phorbol dibutyrate treated muscle increased the phosphorylation from 0.30 to 0.91 mol/mol. Two-dimensional gel electrophoresis followed by two-dimensional tryptic phosphopeptide mapping was used to identify the enzyme involved in the stretch-induced phosphorylation. Quantitation of the [32P]phosphate content of the peptides revealed considerable light chain phosphorylation by protein kinase C only in the phorbol dibutyrate treated arterial muscle, whereas most of the light chain phosphorylation was attributable to myosin light chain kinase. Upon stretch of either the untreated or treated muscle, the total increment in [32P]phosphate incorporation into the light chain could be accounted for by peptides characteristic for myosin light chain kinase catalyzed phosphorylation, demonstrating that the stretch-induced phosphorylation is caused by this enzyme exclusively

Otolith and canal reflexes in human standing

Science.gov (United States)

Cathers, Ian; Day, Brian L; Fitzpatrick, Richard C

2005-01-01

We used galvanic vestibular stimulation (GVS) to identify human balance reflexes of the semicircular canals and otolith organs. The experiment used a model of vestibular signals arising from GVS modulation of the net signal from vestibular afferents. With the head upright, the model predicts that the GVS-evoked canal signal indicates lateral head rotation while the otolith signal indicates lateral tilt or acceleration. Both signify body sway transverse to the head. With the head bent forward, the model predicts that the canal signal indicates body spin about a vertical axis but the otolith signal still signifies lateral body motion. Thus, we compared electromyograms (EMG) in the leg muscles and body sway evoked by GVS when subjects stood with the head upright or bent forward. With the head upright, GVS evoked a large sway in the direction of the anodal electrode. This response was abolished with the head bent forward leaving only small, oppositely directed, transient responses at the start and end of the stimulus. With the head upright, GVS evoked short-latency (60–70 ms), followed by medium-latency (120 ms) EMG responses, of opposite polarity. Bending the head forward abolished the medium-latency but preserved the short-latency response. This is compatible with GVS evoking separate otolithic and canal reflexes, indicating that balance is controlled by independent canal and otolith reflexes, probably through different pathways. We propose that the short-latency reflex and small transient sway are driven by the otolith organs and the medium-latency response and the large sway are driven by the semicircular canals. PMID:15618274

Convective Heat Transfer Scaling of Ignition Delay and Burning Rate with Heat Flux and Stretch Rate in the Equivalent Low Stretch Apparatus

Science.gov (United States)

Olson, Sandra

2011-01-01

To better evaluate the buoyant contributions to the convective cooling (or heating) inherent in normal-gravity material flammability test methods, we derive a convective heat transfer correlation that can be used to account for the forced convective stretch effects on the net radiant heat flux for both ignition delay time and burning rate. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone heater to minimize buoyant effects while at the same time providing a forced stagnation flow on the sample, which ignites and burns as a ceiling fire. Ignition delay and burning rate data is correlated with incident heat flux and convective heat transfer and compared to results from other test methods and fuel geometries using similarity to determine the equivalent stretch rates and thus convective cooling (or heating) rates for those geometries. With this correlation methodology, buoyant effects inherent in normal gravity material flammability test methods can be estimated, to better apply the test results to low stretch environments relevant to spacecraft material selection.

Stretch-sensitive paresis and effort perception in hemiparesis.

Science.gov (United States)

Vinti, Maria; Bayle, Nicolas; Hutin, Emilie; Burke, David; Gracies, Jean-Michel

2015-08-01

In spastic paresis, stretch applied to the antagonist increases its inappropriate recruitment during agonist command (spastic co-contraction). It is unknown whether antagonist stretch: (1) also affects agonist recruitment; (2) alters effort perception. We quantified voluntary activation of ankle dorsiflexors, effort perception, and plantar flexor co-contraction during graded dorsiflexion efforts at two gastrocnemius lengths. Eighteen healthy (age 41 ± 13) and 18 hemiparetic (age 54 ± 12) subjects performed light, medium and maximal isometric dorsiflexion efforts with the knee flexed or extended. We determined dorsiflexor torque, Root Mean Square EMG and Agonist Recruitment/Co-contraction Indices (ARI/CCI) from the 500 ms peak voluntary agonist recruitment in a 5-s maximal isometric effort in tibialis anterior, soleus and medial gastrocnemius. Subjects retrospectively reported effort perception on a 10-point visual analog scale. During gastrocnemius stretch in hemiparetic subjects, we observed: (1) a 25 ± 7 % reduction of tibialis anterior voluntary activation (maximum reduction 98 %; knee extended vs knee flexed; p = 0.007, ANOVA); (2) an increase in dorsiflexion effort perception (p = 0.03, ANCOVA). Such changes did not occur in healthy subjects. Effort perception depended on tibialis anterior recruitment only (βARI(TA) = 0.61, p hemiparesis, voluntary ability to recruit agonist motoneurones is impaired--sometimes abolished--by antagonist stretch, a phenomenon defined here as stretch-sensitive paresis. In addition, spastic co-contraction increases effort perception, an additional incentive to evaluate and treat this phenomenon.

Shoulder reflexes

DEFF Research Database (Denmark)

Diederichsen, L.; Krogsgaard, M.; Voigt, Michael

2002-01-01

long latency (300 ms) excitatory reflex has been found when nerves in the capsule were stimulated electrically during shoulder surgery. In addition, when the anterior-inferior capsule was excited in conscious humans with modest amplitude electrical stimuli during muscle activity, a strong inhibition...... activity around the shoulder. This has implications for rehabilitation and shoulder surgery.......Dynamic shoulder stability is dependent on muscular coordination and sensory inputs. In the shoulder, mechanoreceptors are found in the coracoacromial ligament, the rotator cuff tendons, the musculotendinous junctions of the rotator cuff and in the capsule. The number of receptors in the capsule...

Orthodoxy and reflexivity in international comparative analysis

DEFF Research Database (Denmark)

Lind, Jens; Valkenburg, Ben

2002-01-01

This contribution aims at four points.First we want to argue why we think a reflexive social science is more adequate than the orthodox consensus. In current practice much of the criticism on the orthodox consensus is shared on a theoretical level, without considering the implications and acting...... upon the consequences on the level of empirical research. We want to avoid that, so our second and third subject will be the practical implications of reflexivity for empirical research as well as for social policy. Our discussion on these subjects is based on the practical experiences in the INPART...

Eliciting Sound Memories.

Science.gov (United States)

Harris, Anna

2015-11-01

Sensory experiences are often considered triggers of memory, most famously a little French cake dipped in lime blossom tea. Sense memory can also be evoked in public history research through techniques of elicitation. In this article I reflect on different social science methods for eliciting sound memories such as the use of sonic prompts, emplaced interviewing, and sound walks. I include examples from my research on medical listening. The article considers the relevance of this work for the conduct of oral histories, arguing that such methods "break the frame," allowing room for collaborative research connections and insights into the otherwise unarticulatable.

The reflexive case study method

DEFF Research Database (Denmark)

Rittenhofer, Iris

2015-01-01

This paper extends the international business research on small to medium-sized enterprises (SME) at the nexus of globalization. Based on a conceptual synthesis across disciplines and theoretical perspectives, it offers management research a reflexive method for case study research of postnational...

Effect of spinal manipulative therapy with stretching compared with stretching alone on full-swing performance of golf players: a randomized pilot trial☆

Science.gov (United States)

Costa, Soraya M.V.; Chibana, Yumi E.T.; Giavarotti, Leandro; Compagnoni, Débora S.; Shiono, Adriana H.; Satie, Janice; Bracher, Eduardo S.B.

2009-01-01

Abstract Objective There has been a steady growth of chiropractic treatment using spinal manipulative therapy (SMT) that aims to increase the performance of athletes in various sports. This study evaluates the effect of SMT by chiropractors on the performance of golf players. Methods Golfers of 2 golf clubs in São Paulo, Brazil, participated in this study. They were randomized to 1 of 2 groups: Group I received a stretch program, and group II received a stretch program in addition to SMT. Participants in both groups performed the same standardized stretching program. Spinal manipulative therapy to dysfunctional spinal segments was performed on group II only. All golfers performed 3 full-swing maneuvers. Ball range was considered as the average distance for the 3 shots. Treatment was performed after the initial measurement, and the same maneuvers were performed afterward. Each participant repeated these procedures for a 4-week period. Student t test, Mann-Whitney nonparametric test, and 1-way analysis of variance for repeated measures with significance level of 5% were used to analyze the study. Results Forty-three golfers completed the protocol. Twenty participants were allocated to group I and 23 to group II. Average age, handicap, and initial swing were comparable. No improvement of full-swing performance was observed during the 4 sessions on group I (stretch only). An improvement was observed at the fourth session of group II (P = .005); when comparing the posttreatment, group II had statistical significance at all phases (P = .003). Conclusions Chiropractic SMT in association with muscle stretching may be associated with an improvement of full-swing performance when compared with muscle stretching alone. PMID:19948307

Ca2+ influx and ATP release mediated by mechanical stretch in human lung fibroblasts

International Nuclear Information System (INIS)

Murata, Naohiko; Ito, Satoru; Furuya, Kishio; Takahara, Norihiro; Naruse, Keiji; Aso, Hiromichi; Kondo, Masashi; Sokabe, Masahiro; Hasegawa, Yoshinori

2014-01-01

Highlights: • Uniaxial stretching activates Ca 2+ signaling in human lung fibroblasts. • Stretch-induced intracellular Ca 2+ elevation is mainly via Ca 2+ influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca 2+ influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca 2+ concentration ([Ca 2+ ] i ) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca 2+ ] i transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca 2+ ] i . The stretch-induced [Ca 2+ ] i elevation was attenuated in Ca 2+ -free solution. In contrast, the increase of [Ca 2+ ] i by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd 3+ , ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca 2+ ] i elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca 2+ influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP

Investigating the role of musical genre in human perception of music stretching resistance

OpenAIRE

Chen, Jun; Wang, Chaokun

2017-01-01

To stretch a music piece to a given length is a common demand in people's daily lives, e.g., in audio-video synchronization and animation production. However, it is not always guaranteed that the stretched music piece is acceptable for general audience since music stretching suffers from people's perceptual artefacts. Over-stretching a music piece will make it uncomfortable for human psychoacoustic hearing. The research on music stretching resistance attempts to estimate the maximum stretchab...

Reconceptualizing reflexivity and dissonance in professional and personal domains.

Science.gov (United States)

Brooks, Ann

2008-09-01

Debates around 'reflexivity' and the construction of the gendered self within late modernity have occupied the attention of both 'reflexive modernization' theorists (Beck, Giddens and Lash 1994; Beck and Beck-Gernsheim 1996; Giddens 1991, 1992) as well as gender and feminist theorists. While theorists such as Beck and Giddens have been preoccupied with establishing the connection between reflexivity and the construction of the 'non-gendered' self, gender and feminist theorists have sought to amplify the debate by exploring the intersecting nexus of contemporary theorizing, more fully within this context. This paper explores the theoretical underpinnings of these debates and their application to specific professional and personal domains. I consider three case studies to assess these issues as outlined in my own work, Brooks 2006, and in the work of Wajcman and Martin 2002, and McDowell 1997, which draw on empirical research and explore changes to gender identity within professional and personal domains. I conclude that there is little evidence in the research presented here of any systematic reconfiguring of gender identities leading to a detraditionalization of gender as suggested by the 'reflexive modernization' theorists.

Equibiaxial cyclic stretch stimulates fibroblasts to rapidly remodel fibrin.

Science.gov (United States)

Balestrini, Jenna Leigh; Billiar, Kristen Lawrence

2006-01-01

Understanding the effects of the mechanical environment on wound healing is critical for developing more effective treatments to reduce scar formation and contracture. The aim of this study was to investigate the effects of dynamic mechanical stretch on cell-mediated early wound remodeling independent of matrix alignment which obscures more subtle remodeling mechanisms. Cyclic equibiaxial stretch (16% stretch at 0.2 Hz) was applied to fibroblast-populated fibrin gel in vitro wound models for eight days. Compaction, density, tensile strength, and collagen content were quantified as functional measures of remodeling. Stretched samples were approximately ten times stronger, eight-fold more dense, and eight times thinner than statically cultured samples. These changes were accompanied by a 15% increase in net collagen but no significant differences in cell number or viability. When collagen crosslinking was inhibited in stretched samples, the extensibility increased and the strength decreased. The apparent weakening was due to a reduction in compaction rather than a decrease in ability of the tissue to withstand tensile forces. Interestingly, inhibiting collagen crosslinking had no measurable effects on the statically cultured samples. These results indicate that amplified cell-mediated compaction and even a slight addition in collagen content play substantial roles in mechanically induced wound strengthening. These findings increase our understanding of how mechanical forces guide the healing response in skin, and the methods employed in this study may also prove valuable tools for investigating stretch-induced remodeling of other planar connective tissues and for creating mechanically robust engineered tissues.

Adaptation to sensory-motor reflex perturbations is blind to the source of errors.

Science.gov (United States)

Hudson, Todd E; Landy, Michael S

2012-01-06

In the study of visual-motor control, perhaps the most familiar findings involve adaptation to externally imposed movement errors. Theories of visual-motor adaptation based on optimal information processing suppose that the nervous system identifies the sources of errors to effect the most efficient adaptive response. We report two experiments using a novel perturbation based on stimulating a visually induced reflex in the reaching arm. Unlike adaptation to an external force, our method induces a perturbing reflex within the motor system itself, i.e., perturbing forces are self-generated. This novel method allows a test of the theory that error source information is used to generate an optimal adaptive response. If the self-generated source of the visually induced reflex perturbation is identified, the optimal response will be via reflex gain control. If the source is not identified, a compensatory force should be generated to counteract the reflex. Gain control is the optimal response to reflex perturbation, both because energy cost and movement errors are minimized. Energy is conserved because neither reflex-induced nor compensatory forces are generated. Precision is maximized because endpoint variance is proportional to force production. We find evidence against source-identified adaptation in both experiments, suggesting that sensory-motor information processing is not always optimal.

Emotional Dissonance and Burnout: The Moderating Role of Team Reflexivity and Re-Evaluation.

Science.gov (United States)

Andela, Marie; Truchot, Didier

2017-08-01

The aim of the present study was to better understand the relationship between emotional dissonance and burnout by exploring the buffering effects of re-evaluation and team reflexivity. The study was conducted with a sample of 445 nurses and healthcare assistants from a general hospital. Team reflexivity was evaluated with the validation of the French version of the team reflexivity scale (Facchin, Tschan, Gurtner, Cohen, & Dupuis, 2006). Burnout was measured with the MBI General Survey (Schaufeli, Leiter, Maslach, & Jackson, 1996). Emotional dissonance and re-evaluation were measured with the scale developed by Andela, Truchot, & Borteyrou (2015). With reference to Rimé's theoretical model (2009), we suggested that both dimensions of team reflexivity (task and social reflexivity) respond to both psychological necessities induced by dissonance (cognitive clarification and socio-affective necessities). Firstly, results indicated that emotional dissonance was related to burnout. Secondly, regression analysis confirmed the buffering role of re-evaluation and social reflexivity on the emotional exhaustion of emotional dissonance. Overall, results contribute to the literature by highlighting the moderating effect of re-evaluation and team reflexivity in analysing the relationship between emotional dissonance and burnout. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Lewis lung carcinoma regulation of mechanical stretch-induced protein synthesis in cultured myotubes.

Science.gov (United States)

Gao, Song; Carson, James A

2016-01-01

Mechanical stretch can activate muscle and myotube protein synthesis through mammalian target of rapamycin complex 1 (mTORC1) signaling. While it has been established that tumor-derived cachectic factors can induce myotube wasting, the effect of this catabolic environment on myotube mechanical signaling has not been determined. We investigated whether media containing cachectic factors derived from Lewis lung carcinoma (LLC) can regulate the stretch induction of myotube protein synthesis. C2C12 myotubes preincubated in control or LLC-derived media were chronically stretched. Protein synthesis regulation by anabolic and catabolic signaling was then examined. In the control condition, stretch increased mTORC1 activity and protein synthesis. The LLC treatment decreased basal mTORC1 activity and protein synthesis and attenuated the stretch induction of protein synthesis. LLC media increased STAT3 and AMP-activated protein kinase phosphorylation in myotubes, independent of stretch. Both stretch and LLC independently increased ERK1/2, p38, and NF-κB phosphorylation. In LLC-treated myotubes, the inhibition of ERK1/2 and p38 rescued the stretch induction of protein synthesis. Interestingly, either leukemia inhibitory factor or glycoprotein 130 antibody administration caused further inhibition of mTORC1 signaling and protein synthesis in stretched myotubes. AMP-activated protein kinase inhibition increased basal mTORC1 signaling activity and protein synthesis in LLC-treated myotubes, but did not restore the stretch induction of protein synthesis. These results demonstrate that LLC-derived cachectic factors can dissociate stretch-induced signaling from protein synthesis through ERK1/2 and p38 signaling, and that glycoprotein 130 signaling is associated with the basal stretch response in myotubes. Copyright © 2016 the American Physiological Society.

Soleus muscle H-reflex monitoring in endoscopic surgery under general anesthesia percutaneous interlaminar approach.

Science.gov (United States)

Wang, Huixue; Gao, Yingji; Ji, Lixin; Bai, Wanshan

2018-05-01

The clinical value of soleus muscle H-reflex monitoring in general anesthesia percutaneous interlaminar approach was investigated. A total of 80 cases with unilateral L5-S1 disc herniation between January 2015 and October 2016 were randomly divided into control group (without soleus muscle H-reflex monitoring, n=40) and observation group (with soleus muscle H-reflex monitoring, n=40). Results showed that the operation time of the observation group was shorter than that of the control group (Ph after operation, the amplitude of H-reflex in diseased side soleus muscle was significantly lower than that in healthy side (Ph postoperatively, the latency of H-reflex in diseased side soleus muscle was shorter than that of healthy side (PH-reflex latency in soleus muscle were significantly lower (PH-reflex monitoring can effectively reduce the damage to the nerve roots under percutaneous endoscopic intervertebral endoscopic surgery under general anesthesia, improve the accuracy of surgery, reduce the complications, shorten the operation time and reduce the surgical bleeding, which is more beneficial to patients smooth recovery.

Fundamental Principles underlying Motor Reflexes

NARCIS (Netherlands)

K. Zhou (Kuikui)

2017-01-01

markdownabstractThe cerebellum has been suggested to be involved in motor control ever since the early 19th century. The motor control ranges from timing and strength of simple reflexes to multiple joint/limb coordination and complex motor sequence acquisition. The current thesis discusses the

Effects of special composite stretching on the swing of amateur golf players.

Science.gov (United States)

Lee, Joong-Chul; Lee, Sung-Wan; Yeo, Yun-Ghi; Park, Gi Duck

2015-04-01

[Purpose] The study investigated stretching for safer a golf swing compared to present stretching methods for proper swings in order to examine the effects of stretching exercises on golf swings. [Subjects] The subjects were 20 amateur golf club members who were divided into two groups: an experimental group which performed stretching, and a control group which did not. The subjects had no bone deformity, muscle weakness, muscle soreness, or neurological problems. [Methods] A swing analyzer and a ROM measuring instrument were used as the measuring tools. The swing analyzer was a GS400-golf hit ball analyzer (Korea) and the ROM measuring instrument was a goniometer (Korea). [Results] The experimental group showed a statistically significant improvement in driving distance. After the special stretching training for golf, a statistically significant difference in hit-ball direction deviation after swings were found between the groups. The experimental group showed statistically significant decreases in hit ball direction deviation. After the special stretching training for golf, statistically significant differences in hit-ball speed were found between the groups. The experimental group showed significant increases in hit-ball speed. [Conclusion] To examine the effects of a special stretching program for golf on golf swing-related factors, 20 male amateur golf club members performed a 12-week stretching training program. After the golf stretching training, statistically significant differences were found between the groups in hit-ball driving distance, direction deviation, deflection distance, and speed.

Stretching and folding mechanism in foams

International Nuclear Information System (INIS)

Tufaile, Alberto; Pedrosa Biscaia Tufaile, Adriana

2008-01-01

We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board

Stretching and folding mechanism in foams

Energy Technology Data Exchange (ETDEWEB)

Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

2008-10-13

We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

Functional Imaging of Human Vestibular Cortex Activity Elicited by Skull Tap and Auditory Tone Burst

Science.gov (United States)

Noohi, F.; Kinnaird, C.; Wood, S.; Bloomberg, J.; Mulavara, A.; Seidler, R.

2016-01-01

The current study characterizes brain activation in response to two modes of vestibular stimulation: skull tap and auditory tone burst. The auditory tone burst has been used in previous studies to elicit either the vestibulo-spinal reflex (saccular-mediated colic Vestibular Evoked Myogenic Potentials (cVEMP)), or the ocular muscle response (utricle-mediated ocular VEMP (oVEMP)). Some researchers have reported that air-conducted skull tap elicits both saccular and utricle-mediated VEMPs, while being faster and less irritating for the subjects. However, it is not clear whether the skull tap and auditory tone burst elicit the same pattern of cortical activity. Both forms of stimulation target the otolith response, which provides a measurement of vestibular function independent from semicircular canals. This is of high importance for studying otolith-specific deficits, including gait and balance problems that astronauts experience upon returning to earth. Previous imaging studies have documented activity in the anterior and posterior insula, superior temporal gyrus, inferior parietal lobule, inferior frontal gyrus, and the anterior cingulate cortex in response to different modes of vestibular stimulation. Here we hypothesized that skull taps elicit similar patterns of cortical activity as the auditory tone bursts, and previous vestibular imaging studies. Subjects wore bilateral MR compatible skull tappers and headphones inside the 3T GE scanner, while lying in the supine position, with eyes closed. Subjects received both forms of the stimulation in a counterbalanced fashion. Pneumatically powered skull tappers were placed bilaterally on the cheekbones. The vibration of the cheekbone was transmitted to the vestibular system, resulting in the vestibular cortical response. Auditory tone bursts were also delivered for comparison. To validate our stimulation method, we measured the ocular VEMP outside of the scanner. This measurement showed that both skull tap and auditory

Acid-sensing ion channels contribute to the metaboreceptor component of the exercise pressor reflex

OpenAIRE

McCord, Jennifer L.; Tsuchimochi, Hirotsugu; Kaufman, Marc P.

2009-01-01

The exercise pressor reflex is evoked by both mechanical and metabolic stimuli arising in contracting skeletal muscle. Recently, the blockade of acid-sensing ion channels (ASICs) with amiloride and A-316567 attenuated the reflex. Moreover, amiloride had no effect on the mechanoreceptor component of the reflex, prompting us to determine whether ASICs contributed to the metaboreceptor component of the exercise pressor reflex. The metaboreceptor component can be assessed by measuring mean arteri...

Effects of brainstem lesions on the masseter inhibitory reflex. Functional mechanisms of reflex pathways

NARCIS (Netherlands)

Ongerboer de Visser, B. W.; Cruccu, G.; Manfredi, M.; Koelman, J. H.

1990-01-01

The masseter inhibitory reflex (MIR) was investigated in 16 patients with localized brainstem lesions involving the trigeminal system. The MIR consists of two phases of EMG silence (S1 and S2) evoked by stimulation of the mental nerve during maximal clenching of the teeth. The extent of the lesions

Spasm of the near reflex: a spectrum of anomalies.

Science.gov (United States)

Goldstein, J H; Schneekloth, B B

1996-01-01

Spasm of the near reflex has been characterized as the variable appearance of pseudomyopia, convergent strabismus and miosis. These characteristics may appear together or separately. In addition, abnormalities of accommodation may appear not only as pseudomyopia, but may also be manifest in cases with significant hypermetropia in which the patient is unable to relax accommodation even when plus lenses are used. The intent of this review is to identify the various clinical presentations of anomalies of the entire near reflex as well as the component parts. The relationship to functional and organic disorders are discussed as well as the related neuroanatomy. We suggest that one may more readily understand the clinical manifestations as a spectrum of anomalies of the near reflex rather than a multitude of disconnected entities.

Kinaesthetic ipsilateral and crossed extensor plantar response: A new way to elicit upgoing toe sign (Babinski response?

Directory of Open Access Journals (Sweden)

Abraham Kuruvilla

2011-01-01

Full Text Available We describe a phenomenon of "kinaesthetic extensor plantar response" in advanced pyramidal dysfunction, an interesting observation noted in a patient with dorsal myelopathy. A 44-year-old woman presented with one-year history of gradually progressive weakness and stiffness of both lower limbs along with urge incontinence of urine. Examination showed spontaneous elicitation of extensor plantar response while assessing the tone by rolling method as well as on noxious stimulation of the thigh. Magnetic resonance imaging (MRI of the dorsal spine and digital subtraction angiography showed the presence of spinal dural arteriovenous fistula causing myelopathy. This case exemplifies the fact that in advanced pyramidal dysfunction, not only the receptive field of Babinski reflex may extend to the leg or thigh, but may also integrate with other modalities of stimulation, such as the rolling movement. The possible underlying pathophysiology of such a phenomenon is discussed.

Fatigue Crack Growth Characteristics of Cold Stretched STS 304 Welded Joint

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeong Won; Na, Seong Hyeon; Yoon, Dong Hyun; Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Kim, Young Kyun; Kim, Ki Dong [Korea Gas Coporation R& D Division, Daejeon (Korea, Republic of)

2017-09-15

STS 304 steel is used as pressure vessel material, and although it exhibits excellent mechanical characteristics at a low temperature, it is heavier than other materials. To address this issue, a method using cold-stretching techniques for STS 304 can be applied. In this study, a cold-stretching part and welded joint specimen were directly obtained from a cold-stretching pressure vessel manufactured according to ASME code. Fatigue crack propagation tests were carried out at room temperature and -170℃ using the compliance method for stress ratios of 0.1 and 0.5. The results indicate that crack growth rate of the welded joint is higher than that of the cold-stretching part within the same stress intensity factor range. The outcome of this work is expected to serve as a basis for the development of a cold-stretched STS 304 pressure vessel.

Expert Panel Elicitation

Energy Technology Data Exchange (ETDEWEB)

Jensen, M. [Swedish Radiation Protection Authority, Stockholm (Sweden). Dept. of Waste Management and Environmental Protection; Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States)

2005-09-15

Scientists are now frequently in a situation where data cannot be easily assessed, since they may have conflicting or uncertain sources. While expert judgment reflects private choices, it is possible both reduce the personal aspect as well as in crease confidence in the judgments by using formal protocols for choice and elicitation of experts. A full-scale elicitation made on seismicity following glaciation, now in its late phase and presented here in a preliminary form, illustrates the value of the technique and some essential issues in connection with the decision to launch such a project. The results show an unusual low variation between the experts.

The Gateway Reflex, a Novel Neuro-Immune Interaction for the Regulation of Regional Vessels

Directory of Open Access Journals (Sweden)

Yuki Tanaka

2017-10-01

Full Text Available The gateway reflex is a new phenomenon that explains how immune cells bypass the blood–brain barrier to infiltrate the central nervous system (CNS and trigger neuroinflammation. To date, four examples of gateway reflexes have been discovered, each described by the stimulus that evokes the reflex. Gravity, electricity, pain, and stress have all been found to create gateways at specific regions of the CNS. The gateway reflex, the most recently discovered of the four, has also been shown to upset the homeostasis of organs in the periphery through its action on the CNS. These reflexes provide novel therapeutic targets for the control of local neuroinflammation and organ function. Each gateway reflex is activated by different neural activations and induces inflmammation at different regions in the CNS. Therefore, it is theoretically possible to manipulate each independently, providing a novel therapeutic strategy to control local neuroinflammation and peripheral organ homeostasis.

[Developing team reflexivity as a learning and working tool for medical teams].

Science.gov (United States)

Riskin, Arieh; Bamberger, Peter

2014-01-01

Team reflexivity is a collective activity in which team members review their previous work, and develop ideas on how to modify their work behavior in order to achieve better future results. It is an important learning tool and a key factor in explaining the varying effectiveness of teams. Team reflexivity encompasses both self-awareness and agency, and includes three main activities: reflection, planning, and adaptation. The model of briefing-debriefing cycles promotes team reflexivity. Its key elements include: Pre-action briefing--setting objectives, roles, and strategies the mission, as well as proposing adaptations based on what was previously learnt from similar procedures; Post-action debriefing--reflecting on the procedure performed and reviewing the extent to which objectives were met, and what can be learnt for future tasks. Given the widespread attention to team-based work systems and organizational learning, efforts should be made toward ntroducing team reflexivity in health administration systems. Implementation could be difficult because most teams in hospitals are short-lived action teams formed for a particular event, with limited time and opportunity to consciously reflect upon their actions. But it is precisely in these contexts that reflexive processes have the most to offer instead of the natural impulsive collective logics. Team reflexivity suggests a potential solution to the major problems of iatorgenesis--avoidable medical errors, as it forces all team members to participate in a reflexive process together. Briefing-debriefing technology was studied mainly in surgical teams and was shown to enhance team-based learning and to improve quality-related outcomes and safety.

A tapetal-like fundus reflex in a healthy male

DEFF Research Database (Denmark)

Schatz, Patrik; Bregnhøj, Jesper; Arvidsson, Henrik

2012-01-01

To report on the retinal function and structure in a 37-year-old male who presented with a tapetal-like reflex (TLR) indistinguishable from that seen in female carriers of X-linked retinitis pigmentosa (XLRP).......To report on the retinal function and structure in a 37-year-old male who presented with a tapetal-like reflex (TLR) indistinguishable from that seen in female carriers of X-linked retinitis pigmentosa (XLRP)....

Automated data reduction workflows for astronomy. The ESO Reflex environment

Science.gov (United States)

Freudling, W.; Romaniello, M.; Bramich, D. M.; Ballester, P.; Forchi, V.; García-Dabló, C. E.; Moehler, S.; Neeser, M. J.

2013-11-01

Context. Data from complex modern astronomical instruments often consist of a large number of different science and calibration files, and their reduction requires a variety of software tools. The execution chain of the tools represents a complex workflow that needs to be tuned and supervised, often by individual researchers that are not necessarily experts for any specific instrument. Aims: The efficiency of data reduction can be improved by using automatic workflows to organise data and execute a sequence of data reduction steps. To realize such efficiency gains, we designed a system that allows intuitive representation, execution and modification of the data reduction workflow, and has facilities for inspection and interaction with the data. Methods: The European Southern Observatory (ESO) has developed Reflex, an environment to automate data reduction workflows. Reflex is implemented as a package of customized components for the Kepler workflow engine. Kepler provides the graphical user interface to create an executable flowchart-like representation of the data reduction process. Key features of Reflex are a rule-based data organiser, infrastructure to re-use results, thorough book-keeping, data progeny tracking, interactive user interfaces, and a novel concept to exploit information created during data organisation for the workflow execution. Results: Automated workflows can greatly increase the efficiency of astronomical data reduction. In Reflex, workflows can be run non-interactively as a first step. Subsequent optimization can then be carried out while transparently re-using all unchanged intermediate products. We found that such workflows enable the reduction of complex data by non-expert users and minimizes mistakes due to book-keeping errors. Conclusions: Reflex includes novel concepts to increase the efficiency of astronomical data processing. While Reflex is a specific implementation of astronomical scientific workflows within the Kepler workflow

Hypnotizability, hypnosis and prepulse inhibition of the startle reflex in healthy women: an ERP analysis.

Science.gov (United States)

De Pascalis, Vilfredo; Russo, Emanuela

2013-01-01

A working model of the neurophysiology of hypnosis suggests that highly hypnotizable individuals (HHs) have more effective frontal attentional systems implementing control, monitoring performance, and inhibiting unwanted stimuli from conscious awareness, than low hypnotizable individuals (LHs). Recent studies, using prepulse inhibition (PPI) of the auditory startle reflex (ASR), suggest that HHs, in the waking condition, may show reduced sensory gating although they may selectively attend and disattend different stimuli. Using a within subject design and a strict subject selection procedure, in waking and hypnosis conditions we tested whether HHs compared to LHs showed a significantly lower inhibition of the ASR and startle-related brain activity in both time and intracerebral source localization domains. HHs, as compared to LH participants, exhibited (a) longer latency of the eyeblink startle reflex, (b) reduced N100 responses to startle stimuli, and (c) higher PPI of eyeblink startle and of the P200 and P300 waves. Hypnosis yielded smaller N100 waves to startle stimuli and greater PPI of this component than in the waking condition. sLORETA analysis revealed that, for the N100 (107 msec) elicited during startle trials, HHs had a smaller activation in the left parietal lobe (BA2/40) than LHs. Auditory pulses of pulse-with prepulse trials in HHs yielded less activity of the P300 (280 msec) wave than LHs, in the cingulate and posterior cingulate gyrus (BA23/31). The present results, on the whole, are in the opposite direction to PPI findings on hypnotizability previously reported in the literature. These results provide support to the neuropsychophysiological model that HHs have more effective sensory integration and gating (or filtering) of irrelevant stimuli than LHs.

THE ANXIETY SPECTRUM AND THE REFLEX PHYSIOLOGY OF DEFENSE: FROM CIRCUMSCRIBED FEAR TO BROAD DISTRESS

Science.gov (United States)

McTeague, Lisa M.; Lang, Peter J.

2013-01-01

Guided by the diagnostic nosology, anxiety patients are expected to show defensive hyperarousal during affective challenge, irrespective of the principal phenotype. In the current study, patients representing the whole spectrum of anxiety disorders (i.e., specific phobia, social phobia, panic disorder with or without agoraphobia, obsessive-compulsive disorder, generalized anxiety disorder (GAD), posttraumatic stress disorder(PTSD)), and healthy community control participants, completed an imagery-based fear elicitation paradigm paralleling conventional intervention techniques. Participants imagined threatening and neutral narratives as physiological responses were recorded. Clear evidence emerged for exaggerated reactivity to clinically relevant imagery—most pronounced in startle reflex responding. However, defensive propensity varied across principal anxiety disorders. Disorders characterized by focal fear and impairment (e.g., specific phobia) showed robust fear potentiation. Conversely, for disorders of long-enduring, pervasive apprehension and avoidance with broad anxiety and depression comorbidity (e.g., PTSD secondary to cumulative trauma, GAD), startle responses were paradoxically diminished to all aversive contents. Patients whose expressed symptom profiles were intermediate between focal fearfulness and broad anxious-misery in both severity and chronicity exhibited a still heightened but more generalized physiological propensity to respond defensively. Importantly, this defensive physiological gradient—the inverse of self-reported distress—was evident not only between but also within disorders. These results highlight that fear circuitry could be dysregulated in chronic, pervasive anxiety, and preliminary functional neuroimaging findings suggest that deficient amygdala recruitment could underlie attenuated reflex responding. In summary, adaptive defensive engagement during imagery may be compromised by long-term dysphoria and stress—a phenomenon

Spinal plasticity in robot-mediated therapy for the lower limbs

DEFF Research Database (Denmark)

Stevenson, Andrew James Thomas; Mrachacz-Kersting, Natalie; van Asseldonk, Edwin

2015-01-01

of neural changes in the spinal cord. Here, we review the recent literature on spinal plasticity induced by robotic-based training in humans and propose recommendations for the measurement of spinal plasticity using robotic devices. Evidence for spinal plasticity in humans following robotic training...... but are not part of robotic devices used for training purposes. A further development of robotic devices that include the technology to elicit stretch reflexes would allow for the spinal circuitry to be routinely tested as a part of the training and evaluation protocols.......Robot-mediated therapy can help improve walking ability in patients following injuries to the central nervous system. However, the efficacy of this treatment varies between patients, and evidence for the mechanisms underlying functional improvements in humans is poor, particularly in terms...

The effectiveness of manual stretching in the treatment of plantar heel pain: a systematic review

Directory of Open Access Journals (Sweden)

Parish Ben

2011-06-01

Full Text Available Abstract Background Plantar heel pain is a commonly occurring foot complaint. Stretching is frequently utilised as a treatment, yet a systematic review focusing only on its effectiveness has not been published. This review aimed to assess the effectiveness of stretching on pain and function in people with plantar heel pain. Methods Medline, EMBASE, CINAHL, AMED, and The Cochrane Library were searched from inception to July 2010. Studies fulfilling the inclusion criteria were independently assessed, and their quality evaluated using the modified PEDro scale. Results Six studies including 365 symptomatic participants were included. Two compared stretching with a control, one study compared stretching to an alternative intervention, one study compared stretching to both alternative and control interventions, and two compared different stretching techniques and durations. Quality rating on the modified Pedro scale varied from two to eight out of a maximum of ten points. The methodologies and interventions varied significantly between studies, making meta-analysis inappropriate. Most participants improved over the course of the studies, but when stretching was compared to alternative or control interventions, the changes only reached statistical significance in one study that used a combination of calf muscle stretches and plantar fascia stretches in their stretching programme. Another study comparing different stretching techniques, showed a statistically significant reduction in some aspects of pain in favour of plantar fascia stretching over calf stretches in the short term. Conclusions There were too few studies to assess whether stretching is effective compared to control or other interventions, for either pain or function. However, there is some evidence that plantar fascia stretching may be more effective than Achilles tendon stretching alone in the short-term. Appropriately powered randomised controlled trials, utilizing validated outcome

Weak depth and along-strike variations in stretching from a multi-episodic finite stretching model: Evidence for uniform pure-shear extension in the opening of the South China Sea

Science.gov (United States)

Chen, Lin; Zhang, Zhongjie; Song, Haibin

2013-12-01

The South China Sea is widely believed to have been opened by seafloor spreading during the Cenozoic. The details of its lithospheric extension are still being debated, and it is unknown whether pure, simple, or conjunct shears are responsible for the opening of the South China Sea. The depth-dependent and along-strike extension derived from the single-stage finite stretching model or instantaneous stretching model is inconsistent with the observation that the South China Sea proto-margins have experienced multi-episodic extension since the Late Cretaceous. Based on the multi-episodic finite stretching model, we present the amount of lithosphere stretching at the northern continental margin of the South China Sea for different depth scales (upper crust, whole crust and lithosphere) and along several transects. The stretching factors are estimated by integrating seven deep-penetration seismic profiles, the Moho distribution derived from gravity modeling, and the tectonic subsidence data for 41 wells. The results demonstrate that the amount of stretching increases rapidly from 1.1 at the continent shelf to over 3.5 at the lower slope, but the stretching factors at the crust and lithosphere scales are consistent within error (from the uncertainty in paleobathymetry and sea-level change). Furthermore, the along-strike variation in stretching factor is within the range of 1.11-1.9 in west-east direction, accompanied by significant west-east differences in the thickness of high-velocity layers (HVLs) within the lowermost crust. This weak along-strike variation of the stretching factor is most likely produced by the preexisting contrasts in the composition and thermal structure of the lithosphere. The above observations suggest that the continental extension in the opening of the South China Sea mainly takes the form of a uniform pure shear rather than depth-dependent stretching.

All-passive pixel super-resolution of time-stretch imaging

Science.gov (United States)

Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; So, Hayden K. H.; Lam, Edmund Y.; Tsia, Kevin K.

2017-03-01

Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate — hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)—more than four times lower than the originally required readout rate (20 GSa/s) — is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.

Stretching the Border

DEFF Research Database (Denmark)

Horstmann, Alexander

2014-01-01

In this paper, I hope to add a complementary perspective to James Scott’s recent work on avoidance strategies of subaltern mountain people by focusing on what I call the refugee public. The educated Karen elite uses the space of exile in the Thai borderland to reconstitute resources and to re-ent......-based organizations succeed to stretch the border by establishing a firm presence that is supported by the international humanitarian economy in the refugee camps in Northwestern Thailand....

A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

KAUST Repository

Chang, Y.-H.

2018-02-26

Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non-planar transverse stretching process was employed in this study to produce micro-porous structure. The morphology, membrane thickness, mean pore size, and porosity of the PTFE membrane were investigated. The results show that the non-planar transverse stretched membranes exhibit more uniform average pore diameter with thinner membrane thickness. Morphological changes induced by planar and non-planar transverse stretching for pore characteristics were investigated. The stretching conditions, stretching temperature and rate, affect the stretched membrane. Increasing temperature facilitated the uniformity of pore size and uniformity of membrane thickness. Moreover, increase in stretching rate resulted in finer pore size and thinner membrane.

Different corticospinal control between discrete and rhythmic movement of the ankle

OpenAIRE

Goto, Yumeno; Jono, Yasutomo; Hatanaka, Ryota; Nomura, Yoshifumi; Tani, Keisuke; Chujo, Yuta; Hiraoka, Koichi

2014-01-01

We investigated differences in corticospinal and spinal control between discrete and rhythmic ankle movements. Motor evoked potentials (MEPs) in the tibialis anterior and soleus muscles and soleus H-reflex were elicited in the middle of the plantar flexion phase during discrete ankle movement or in the initial or later cycles of rhythmic ankle movement. The H-reflex was evoked at an intensity eliciting a small M-wave and MEPs were elicited at an intensity of 1.2 times the motor threshold of t...

Functionality of the contralateral biceps femoris reflex response during human walking

DEFF Research Database (Denmark)

Stevenson, Andrew James Thomas; Geertsen, Svend Sparre; Sinkjaer, Thomas

2014-01-01

of the body in order to maintain dynamic equilibrium during walking. Therefore, we hypothesized that if we suddenly slowed the treadmill participants were walking on, the cBF reflex would be inhibited because the necessity to break the forward progression of the body would be decreased. Conversely, if we...... the treadmill velocity was altered concurrently or 50 ms after knee perturbation onset. These results, together with the finding that the cBF reflex response is under some cortical control [1], strongly suggest a functional role for the cBF reflex during walking that is adaptable to the environmental situation....

Theory of high-force DNA stretching and overstretching.

Science.gov (United States)

Storm, C; Nelson, P C

2003-05-01

Single-molecule experiments on single- and double-stranded DNA have sparked a renewed interest in the force versus extension of polymers. The extensible freely jointed chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded DNA, but this model does not satisfactorily describe recent high-force stretching data. We instead propose a model (the discrete persistent chain) that borrows features from both the FJC and the wormlike chain, and show that it resembles the data more closely. We find that most of the high-force behavior previously attributed to stretch elasticity is really a feature of the corrected entropic elasticity; the true stretch compliance of single-stranded DNA is several times smaller than that found by previous authors. Next we elaborate our model to allow coexistence of two conformational states of DNA, each with its own stretch and bend elastic constants. Our model is computationally simple and gives an excellent fit through the entire overstretching transition of nicked, double-stranded DNA. The fit gives the first value for the bend stiffness of the overstretched state. In particular, we find the effective bend stiffness for DNA in this state to be about 12 nm k(B)T, a value quite different from either the B-form or single-stranded DNA.

The Acute Effects of Upper Extremity Stretching on Throwing Velocity in Baseball Throwers

Directory of Open Access Journals (Sweden)

Michael Williams

2013-01-01

Full Text Available Purpose. To examine the effects of static and proprioceptive neuromuscular facilitation (PNF stretching of the shoulder internal rotators on throwing velocity. Subjects. 27 male throwers (mean age = 25.1 years old, SD = 2.4 with adequate knowledge of demonstrable throwing mechanics. Study Design. Randomized crossover trial with repeated measures. Methods. Subjects warmed up, threw 10 pitches at their maximum velocity, were randomly assigned to 1 of 3 stretching protocols (static, PNF, or no stretch, and then repeated their 10 pitches. Velocities were recorded after each pitch and average and peak velocities were recorded after each session. Results. Data were analyzed using a repeated measures ANOVA. No significant interaction between stretching and throwing velocity was observed. Main effects for time were not statistically significant. Main effects for the stretching groups were statistically significant. Discussion. Results suggest that stretching of the shoulder internal rotators did not significantly affect throwing velocity immediately after stretching. This may be due to the complexity of the throwing task. Conclusions. Stretching may be included in a thrower's warm-up without any effects on throwing velocity. Further research should be performed using a population with more throwing experience and skill.

Efficacy of hamstring stretching programs in schoolchildren. A systematic review

Directory of Open Access Journals (Sweden)

Carlos-Alberto BECERRA FERNANDEZ

2017-03-01

Full Text Available The main purpose of the present review was to examine the scientific literature on the effects of physical education-based stretching programs on hamstring extensibility in schoolchildren aged 6-11 years. For this purpose relevant studies were searched from ten electronic databases dated up through May 2015. Of the 25 potentially relevant articles identified and retrieved for more detailed evaluation, only eight studies were included in the present review because they met the inclusion criteria. The overall results showed that incorporating hamstring stretching as a part of physical education classes produces a significant improvement in the scores of the tests: straight leg raise and classic sit-and-reach, for the experimental groups, but not for control groups. Stretching programs can be included in Physical Education classes, specifically during the warm-up and the cool down periods in order to improve hamstring extensibility. Although it seems that the stretching exercises in the warm-up period could be less effective in gaining flexibility in school children. Studies that use a stretching volume between 4 and 7 minutes per session and 2-4 training classes per week, obtain statistically significant improvements on the levels of hamstring flexibility in the experimental groups. However, after a five-week detraining period, children revert back to their initial flexibility levels. Therefore, it seems appropriate that physical education teachers should implement stretching programs to improve the students´ flexibility during the Physical Education classes.

Implementation of a controller for linear positioners applicable in optical fiber stretching

International Nuclear Information System (INIS)

Castrillo Piedra, Andres Rodolfo

2014-01-01

A low cost controller is implemented for linear positioners applicable in optic fiber stretching. The possibility of using a donated equipment is evaluated by the Escuela de Ingenieria Mecanica. The equipment is required by the non-linear photonic research laboratory (NLPR-LAB) for stretching of micro structured fiber. The process has required a slow and precise stretching, so the controllers must be precisely programmed to rotate the motors at different speeds. Donated equipment is evaluated to see if it is possible to use for fiber stretching [es

Contribution of the maculo-ocular reflex to gaze stability in the rabbit.

Science.gov (United States)

Pettorossi, V E; Errico, P; Santarelli, R M

1991-01-01

The contribution of the maculo-ocular reflex to gaze stability was studied in 10 pigmented rabbits by rolling the animals at various angles of sagittal inclination of the rotation and/or longitudinal animal axes. At low frequencies (0.005-0.01 Hz) of sinusoidal stimulation the vestibulo-ocular reflex (VOR) was due to macular activation, while at intermediate and high frequencies it was mainly due to ampullar activation. The following results were obtained: 1) maculo-ocular reflex gain decreased as a function of the cosine of the angle between the rotation axis and the earth's horizontal plane. No change in gain was observed when longitudinal animal axis alone was inclined. 2) At 0 degrees of rotation axis and with the animal's longitudinal axis inclination also set at 0 degrees, the maculo-ocular reflex was oriented about 20 degrees forward and upward with respect to the earth's vertical axis. This orientation remained constant with sagittal inclinations of the rotation and/or longitudinal animal axes ranging from approximately 5 degrees upward to 30 degrees downward. When the longitudinal animal axis was inclined beyond these limits, the eye trajectory tended to follow the axis inclination. In the upside down position, the maculo-ocular reflex was anticompensatory, oblique and fixed with respect to orbital coordinates. 3) Ampullo-ocular reflex gain did not change with inclinations of the rotation and/or longitudinal animal axes. The ocular responses were consistently oriented to the stimulus plane. At intermediate frequencies the eye movement trajectory was elliptic because of directional differences between the ampullo- and maculo-ocular reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Damage percolation during stretch flange forming of aluminum alloy sheet

Science.gov (United States)

Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

2005-12-01

A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

VizieR Online Data Catalog: RefleX : X-ray-tracing code (Paltani+, 2017)

Science.gov (United States)

Paltani, S.; Ricci, C.

2017-11-01

We provide here the RefleX executable, for both Linux and MacOSX, together with the User Manual and example script file and output file Running (for instance): reflex_linux will produce the file reflex.out Note that the results may differ slightly depending on the OS, because of slight differences in some implementations numerical computations. The difference are scientifically meaningless. (5 data files).

Erecting Closets and Outing Ourselves: Uncomfortable Reflexivity and Community-Based Research

Science.gov (United States)

Reed, Sarah J.; Miller, Robin Lin; Nnawulezi, Nkiru; Valenti, Maria T.

2012-01-01

Feminist scholars and community psychologists have argued that reflexivity is a necessary component to conducting socially conscious research. Reflexivity, however, is rarely evident in community psychology. In this article, we share the uncomfortable realities that surfaced during a community-based research project in which we adapted and…

Magnetic and electric stimulation to elicit the masseteric exteroceptive suppression period

DEFF Research Database (Denmark)

Komiyama, Osamu; Wang, Kelun; Svensson, Peter

2010-01-01

: In contrast to electrical stimulation, both ES1 and ES2 appeared and saturated with painless magnetic stimuli. SIGNIFICANCE: The present results indicate that both ES1 and ES2 have a non-nociceptive origin. Painless magnetic stimuli will be an advantage in ES reflex examinations for various orofacial pain......OBJECTIVES: The present study compared the perception of electric and magnetic stimuli for reflex appearance threshold (RT) and reflex saturation threshold (RS) of the exteroceptive suppression reflex (ES) in the masseter muscle. METHODS: Twelve healthy males and 12 females (age: 24.2+/-3.2 years......) participated. The surface EMG was recorded from the left masseter muscle. The stimulus intensities were set as multiple values of the sensory threshold (ST), and were applied to the skin above the left mental nerve. Subjects reported the perceived intensity of the stimulus on a numeric rating scale (NRS) at RT...

Coherent time-stretch transformation for real-time capture of wideband signals.

Science.gov (United States)

Buckley, Brandon W; Madni, Asad M; Jalali, Bahram

2013-09-09

Time stretch transformation of wideband waveforms boosts the performance of analog-to-digital converters and digital signal processors by slowing down analog electrical signals before digitization. The transform is based on dispersive Fourier transformation implemented in the optical domain. A coherent receiver would be ideal for capturing the time-stretched optical signal. Coherent receivers offer improved sensitivity, allow for digital cancellation of dispersion-induced impairments and optical nonlinearities, and enable decoding of phase-modulated optical data formats. Because time-stretch uses a chirped broadband (>1 THz) optical carrier, a new coherent detection technique is required. In this paper, we introduce and demonstrate coherent time stretch transformation; a technique that combines dispersive Fourier transform with optically broadband coherent detection.

A critical reflexive Perspective on othering in collaborative knowledge production

DEFF Research Database (Denmark)

Jakobsen, Helle Nordentoft; Olesen, Birgitte Ravn

2018-01-01

Purpose The purpose of the article is to show power mechanisms of in- and exclusion in moments where certain participants appeared to be othered in two collaborative research and development projects in a health care setting. Design/methodology/approach The article contributes to critical......-reflexive analyses of reflexive processes within collaborative knowledge production We use an analytical framework combining Bakhtin and Foucault to investigate processes of inclusion and exclusion in the interplay between dominant and subordinated voices in a moment-by-moment analysis of two incidents from...... interdisciplinary workshops. Findings The analysis illuminates how differences between voices challenge participants’ reflexive awareness and lead to the reproduction of contextual power and knowledge hierarchies and the concomitant silencing of particular participants. Thus, the findings draw attention...

The Reflexive Principle of Sociological Theorization

Directory of Open Access Journals (Sweden)

R T Ubaidullayeva

2013-12-01

Full Text Available The article attempts to describe the reflexive principle in theory-making, which integrates the basic modern methodological paradigms and lays the foundation for the development of sociology. On the basis of the theoretical ideas of P. Bourdieu, A. Giddens and P. Ricoeur the author defines the concept of social reflexion and reveals its peculiarities in sociology as compared to reflexion in philosophy. According to the author, the fulfillment of reflexive functions in sociology is connected with the task of analyzing the complex structure of the polysemantic object, considering the specific quality of the subjects and their various trends of development. The presence of the poles — objectivity-subjectivity, rationality-irrationality, consciousness-unconsciousness etc, requires a reproduction of the dichotomies engendering them in social life and development of cognitive methods for their study in sociology.

Grounded theory research: literature reviewing and reflexivity.

Science.gov (United States)

McGhee, Gerry; Marland, Glenn R; Atkinson, Jacqueline

2007-11-01

This paper is a report of a discussion of the arguments surrounding the role of the initial literature review in grounded theory. Researchers new to grounded theory may find themselves confused about the literature review, something we ourselves experienced, pointing to the need for clarity about use of the literature in grounded theory to help guide others about to embark on similar research journeys. The arguments for and against the use of a substantial topic-related initial literature review in a grounded theory study are discussed, giving examples from our own studies. The use of theoretically sampled literature and the necessity for reflexivity are also discussed. Reflexivity is viewed as the explicit quest to limit researcher effects on the data by awareness of self, something seen as integral both to the process of data collection and the constant comparison method essential to grounded theory. A researcher who is close to the field may already be theoretically sensitized and familiar with the literature on the study topic. Use of literature or any other preknowledge should not prevent a grounded theory arising from the inductive-deductive interplay which is at the heart of this method. Reflexivity is needed to prevent prior knowledge distorting the researcher's perceptions of the data.

Ca{sup 2+} influx and ATP release mediated by mechanical stretch in human lung fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Murata, Naohiko [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Ito, Satoru, E-mail: itori@med.nagoya-u.ac.jp [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Furuya, Kishio [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Takahara, Norihiro [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Naruse, Keiji [Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Okayama 700-8558 (Japan); Aso, Hiromichi; Kondo, Masashi [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Sokabe, Masahiro [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Hasegawa, Yoshinori [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan)

2014-10-10

Highlights: • Uniaxial stretching activates Ca{sup 2+} signaling in human lung fibroblasts. • Stretch-induced intracellular Ca{sup 2+} elevation is mainly via Ca{sup 2+} influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca{sup 2+} influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca{sup 2+} concentration ([Ca{sup 2+}]{sub i}) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca{sup 2+}]{sub i} transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca{sup 2+}]{sub i}. The stretch-induced [Ca{sup 2+}]{sub i} elevation was attenuated in Ca{sup 2+}-free solution. In contrast, the increase of [Ca{sup 2+}]{sub i} by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd{sup 3+}, ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca{sup 2+}]{sub i} elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca{sup 2+} influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP.

Collaborative Research in Contexts of Inequality: The Role of Social Reflexivity

Science.gov (United States)

Leibowitz, Brenda; Bozalek, Vivienne; Farmer, Jean; Garraway, James; Herman, Nicoline; Jawitz, Jeff; McMillan, Wendy; Mistri, Gita; Ndebele, Clever; Nkonki, Vuyisile; Quinn, Lynn; van Schalkwyk, Susan; Vorster, Jo-Anne; Winberg, Chris

2017-01-01

This article reports on the role and value of social reflexivity in collaborative research in contexts of extreme inequality. Social reflexivity mediates the enablements and constraints generated by the internal and external contextual conditions impinging on the research collaboration. It fosters the ability of participants in a collaborative…

Transient filament stretching rheometer II

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1997-01-01

The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

Investing in a Large Stretch Press

Science.gov (United States)

Choate, M.; Nealson, W.; Jay, G.; Buss, W.

1986-01-01

Press for forming large aluminum parts from plates provides substantial economies. Study assessed advantages and disadvantages of investing in large stretch-forming press, and also developed procurement specification for press.

Effect of joint mobilization on the H Reflex amplitude in people with spasticity

OpenAIRE

Pérez Parra, Julio Ernesto; Henao Lema, Claudia Patricia

2011-01-01

Objective: To determine the effect of ankle joint mobilization on the H reflex amplitude of thesoleus muscle in people with spasticity. Materials and methods: A quasi-experimental study withcrossover design and simple masking was conducted in 24 randomized subjects to initiate thecontrol or experimental group. Traction and rhythmic oscillation were applied for five minutesto the ankle joint. H wave amplitude changes of Hoffmann reflex (electrical equivalent of themonosynaptic spinal reflex) w...

Elicitation of ostomy pouch preferences

DEFF Research Database (Denmark)

Bonnichsen, Ole

2011-01-01

Background: Previous studies about patients who have undergone ostomy surgery commonly address the issues of the surgery, complications, preoperative counseling, quality of life, and psychosocial changes following surgery. Only a limited number of studies deal with how technical improvements...... in stoma care would affect patients and, to the author's knowledge, the present study is the first to elicit preferences for potential improvements in ostomy pouches in the form of monetary values. Objective: This article examines and measures Swedish patients' preferences for potential improvements...... in ostomy pouch attributes. The theory, study design, elicitation procedure, and resulting preference structure of the sample is described. Methods: A discrete-choice experiment (DCE) was used to elicit preferences. Respondents were asked to choose between alternatives in choice sets, in which each...

A SYSTEMATIC LITERATURE REVIEW ABOUT SOFTWARE REQUIREMENTS ELICITATION

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LENIS R. WONG

2017-02-01

Full Text Available Requirements Elicitation is recognized as one of the most important activity in software development process as it has direct impact on its success. Although there are many proposals for improving this task, still there are issues which have to be solved. This paper aims to identify the current status of the latest researches related to software requirements elicitation through general framework for literature review, in order to answer the following research questions: Q1 What aspects have been covered by different proposal of requirements elicitation? Q2 What activities of the requirements elicitation process have been covered? And Q3 What factors influence on requirements elicitation and how? A cross-analysis of the outcome was performed. One of the results showed that requirements elicitation process needs improvements.

Optimal stretching in the reacting wake of a bluff body.

Science.gov (United States)

Wang, Jinge; Tithof, Jeffrey; Nevins, Thomas D; Colón, Rony O; Kelley, Douglas H

2017-12-01

We experimentally study spreading of the Belousov-Zhabotinsky reaction behind a bluff body in a laminar flow. Locations of reacted regions (i.e., regions with high product concentration) correlate with a moderate range of Lagrangian stretching and that range is close to the range of optimal stretching previously observed in topologically different flows [T. D. Nevins and D. H. Kelley, Phys. Rev. Lett. 117, 164502 (2016)]. The previous work found optimal stretching in a closed, vortex dominated flow, but this article uses an open flow and only a small area of appreciable vorticity. We hypothesize that optimal stretching is common in advection-reaction-diffusion systems with an excitation threshold, including excitable and bistable systems, and that the optimal range depends on reaction chemistry and not on flow shape or characteristic speed. Our results may also give insight into plankton blooms behind islands in ocean currents.

A reflexing electron microwave amplifier for rf particle accelerator applications

International Nuclear Information System (INIS)

Fazio, M.V.; Hoeberling, R.F.

1988-01-01

The evolution of rf-accelerator technology toward high-power, high-current, low-emittance beams produces an ever-increasing demand for efficient, very high power microwave power sources. The present klystron technology has performed very well but is not expected to produce reliable gigawatt peak-power units in the 1- to 10-GHz regime. Further major advancements must involve other types of sources. The reflexing-electron class of sources can produce microwave powers at the gigawatt level and has demonstrated operation from 800-MHz to 40-GHz. The pulse length appears to be limited by diode closure, and reflexing-electron devices have been operated in a repetitively pulsed mode. A design is presented for a reflexing electron microwave amplifier that is frequency and phase locked. In this design, the generated microwave power can be efficiently coupled to one or several accelerator loads. Frequency and phase-locking capability may permit parallel-source operation for higher power. The low-frequency (500-MHz to 10-GHz) operation at very high power required by present and proposed microwave particle accelerators makes an amplifier, based on reflexing electron phenomena, a candidate for the development of new accelerator power sources. (author)

Stretching of material lines in pseudo-turbulence induced by small rising bubbles

International Nuclear Information System (INIS)

Tanaka, M; Tsujimura, Y; Kanatani, H

2011-01-01

Direct numerical simulations have been conducted for the stretching of material lines in pseudo-turbulence induced by small rising bubbles in order to understand the mixing characteristics of bubbly flows. Contaminated bubbles are considered and are treated as light solid particles. An immersed boundary method has been used for evaluating the coupling force between the bubbles and the surrounding fluid flows. Numerical results show that the total length of material lines increases exponentially in time as a result of stretching and folding due to the rising bubbles. The material lines tend to accumulate in the wake regions of the bubbles, and they are strongly stretched in the vertical direction there. It is also found that the stretching rate of material lines increases with the mean void fraction when it is normalized by the magnitude of the rate-of-strain tensor of liquid flow in pseudo-turbulence. In the case of high void fractions, material lines tend to align with the direction of maximum stretching, and are effectively stretched.

Stretching of material lines in pseudo-turbulence induced by small rising bubbles

Energy Technology Data Exchange (ETDEWEB)

Tanaka, M; Tsujimura, Y; Kanatani, H, E-mail: mtanaka@kit.ac.jp [Department of Mechanical and System Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)

2011-12-22

Direct numerical simulations have been conducted for the stretching of material lines in pseudo-turbulence induced by small rising bubbles in order to understand the mixing characteristics of bubbly flows. Contaminated bubbles are considered and are treated as light solid particles. An immersed boundary method has been used for evaluating the coupling force between the bubbles and the surrounding fluid flows. Numerical results show that the total length of material lines increases exponentially in time as a result of stretching and folding due to the rising bubbles. The material lines tend to accumulate in the wake regions of the bubbles, and they are strongly stretched in the vertical direction there. It is also found that the stretching rate of material lines increases with the mean void fraction when it is normalized by the magnitude of the rate-of-strain tensor of liquid flow in pseudo-turbulence. In the case of high void fractions, material lines tend to align with the direction of maximum stretching, and are effectively stretched.

Fixed Pupillary Light Reflex due to Peripheral Neuropathy after Liver Transplantation

Directory of Open Access Journals (Sweden)

Kwan Hyung Kim

2015-08-01

Full Text Available A 46-year-old female patient was admitted to the intensive care unit (ICU after liver transplantation. About an hour later after the ICU admission, she had no pupillary light reflex. Both pupils were also fixed at 5 mm. Patients who undergo liver transplantation are susceptible to neurologic disorders including hepatic encephalopathy, thromboembolism and intracranial hemorrhage. Abnormal pupillary light reflex usually indicates a serious neurologic emergency in these patients; however, benign neurologic disorders such as peripheral autonomic neuropathy or Holmes-Adie syndrome should also be considered. We experienced a case of fixed pupillary light reflex after liver transplantation diagnosed as peripheral autonomic neuropathy.

Effect of straining on diaphragmatic crura with identification of the straining-crural reflex. The "reflex theory" in gastroesophageal competence

Directory of Open Access Journals (Sweden)

El Sibai Olfat

2004-09-01

Full Text Available Abstract Background The role of the crural diaphragm during increased intra-abdominal pressure is not exactly known. We investigated the hypothesis that the crural diaphragm undergoes reflex phasic contraction on elevation of the intra-abdominal pressure with a resulting increase of the lower esophageal pressure and prevention of gastro-esophageal reflux. Methods The esophageal pressure and crural diaphragm electromyographic responses to straining were recorded in 16 subjects (10 men, 6 women, age 36.6 ± 11.2 SD years during abdominal hernia repair. The electromyogram of crural diaphragm was recorded by needle electrode inserted into the crural diaphragm, and the lower esophageal pressure by a saline-perfused catheter. The study was repeated after crural anesthetization and after crural infiltration with saline. Results The crural diaphragm exhibited resting electromyographic activity which showed a significant increase on sudden (coughing, p Conclusions Straining effected an increase of the electromyographic activity of the crural diaphragm and of the lower esophageal pressure. This effect is suggested to be reflex in nature and to be mediated through the "straining-crural reflex". The crural diaphragm seems to play a role in the lower esophageal competence mechanism. Further studies are required to assess the clinical significance of the current results in gastro-esophageal reflux disease and hiatus hernia.

Restoring walking after spinal cord injury: operant conditioning of spinal reflexes can help.

Science.gov (United States)

Thompson, Aiko K; Wolpaw, Jonathan R

2015-04-01

People with incomplete spinal cord injury (SCI) frequently suffer motor disabilities due to spasticity and poor muscle control, even after conventional therapy. Abnormal spinal reflex activity often contributes to these problems. Operant conditioning of spinal reflexes, which can target plasticity to specific reflex pathways, can enhance recovery. In rats in which a right lateral column lesion had weakened right stance and produced an asymmetrical gait, up-conditioning of the right soleus H-reflex, which increased muscle spindle afferent excitation of soleus, strengthened right stance and eliminated the asymmetry. In people with hyperreflexia due to incomplete SCI, down-conditioning of the soleus H-reflex improved walking speed and symmetry. Furthermore, modulation of electromyographic activity during walking improved bilaterally, indicating that a protocol that targets plasticity to a specific pathway can trigger widespread plasticity that improves recovery far beyond that attributable to the change in the targeted pathway. These improvements were apparent to people in their daily lives. They reported walking faster and farther, and noted less spasticity and better balance. Operant conditioning protocols could be developed to modify other spinal reflexes or corticospinal connections; and could be combined with other therapies to enhance recovery in people with SCI or other neuromuscular disorders. © The Author(s) 2014.

Discriminative ability of reflex receptive fields to distinguish patients with acute and chronic low back pain.

Science.gov (United States)

Müller, Monika; Biurrun Manresa, José A; Treichel, Fabienne; Agten, Christoph A; Heini, Paul; Andersen, Ole K; Curatolo, Michele; Jüni, Peter

2016-12-01

Low back pain has a life time prevalence of 70% to 85%. Approximately 10% to 20% of all patients experience recurrent episodes or develop chronic low back pain. Sociodemographic, clinical, and psychological characteristics explain the transition from acute to chronic low back pain only to a limited extent. Altered central pain processing may be a contributing mechanism. The measurement of reflex receptive fields (RRF) is a novel method to assess altered central pain processing. The RRF area denotes the area of the foot sole from which spinal nociceptive reflexes can be elicited. It was shown to be enlarged in patients with acute and chronic low back pain compared with pain-free individuals. The aim of the study was to explore the discriminative ability of the RRF to distinguish patients with acute and chronic low back pain with the hypothesis that enlarged RRF are associated with chronic low back pain. We included 214 patients with either acute or chronic low back pain and compared RRF between groups in both univariable and multivariable analyses adjusted for different sociodemographic and clinical characteristics possibly associated with the transition to chronic pain. We found a mean difference between patients with acute and chronic low back pain of -0.01 (95% confidence interval [CI], -0.06 to 0.04) in the crude, -0.02 (95% CI, -0.08 to 0.04) in the age and sex adjusted, and -0.02 (95% CI, -0.09 to 0.05) in the fully adjusted model. Our results suggest that the enlargement of RRF area may not be associated with the transition from acute to chronic low back pain.

The effects of prepulse-blink reflex trial repetition and prepulse change on blink reflex modification at short and long lead intervals.

Science.gov (United States)

Lipp, O V; Siddle, D A

1998-01-01

Prepulse inhibition and facilitation of the blink reflex are said to reflect different responses elicited by the lead stimulus, transient detection and orienting response respectively. Two experiments investigated the effects of trial repetition and lead stimulus change on blink modification. It was hypothesized that these manipulations will affect orienting and thus blink facilitation to a greater extent than they will affect transient detection and thus blink inhibition. In Experiment 1 (N = 64), subjects were trained with a sequence of 12 lead stimulus and 12 blink stimulus alone presentations, and 24 lead stimulus-blink stimulus pairings. Lead interval was 120 ms for 12 of the trials and 2000 ms for the other 12. For half the subjects this sequence was followed by a change in pitch of the lead stimulus. In Experiment 2 (N = 64), subjects were trained with a sequence of 36 blink alone stimuli and 36 lead stimulus-blink stimulus pairings. The lead interval was 120 ms for half the subjects and 2000 ms for the other half. The pitch of the lead stimulus on prestimulus trials 31-33 was changed for half the subjects in each group. In both experiments, the amount of blink inhibition decreased during training whereas the amount of blink facilitation remained unchanged. Lead stimulus change had no effect on blink modification in either experiment although it resulted in enhanced skin conductance responses and greater heart rate deceleration in Experiment 2. The present results are not consistent with the notion that blink facilitation is linked to orienting whereas blink inhibition reflects a transient detection mechanism.

Fatigue and muscle-tendon stiffness after stretch-shortening cycle and isometric exercise.

Science.gov (United States)

Toumi, Hechmi; Poumarat, Georges; Best, Thomas M; Martin, Alain; Fairclough, John; Benjamin, Mike

2006-10-01

The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch-shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90 degrees of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle-tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.

The legacy of care as reflexive learning.

Science.gov (United States)

García, Marta Rodríguez; Moya, Jose Luis Medina

2016-06-14

to analyze whether the tutor's use of reflexive strategies encourages the students to reflect. The goal is to discover what type of strategies can help to achieve this and how tutors and students behave in the practical context. a qualitative and ethnographic focus was adopted. Twenty-seven students and 15 tutors from three health centers participated. The latter had received specific training on reflexive clinical tutoring. The analysis was developed through constant comparisons of the categories. the results demonstrate that the tutors' use of reflexive strategies such as didactic questioning, didactic empathy and pedagogical silence contributes to encourage the students' reflection and significant learning. reflexive practice is key to tutors' training and students' learning. analisar se o uso de estratégias reflexivas por parte da tutora de estágio clínico estimula a reflexão nos estudantes. A intenção é descobrir qual tipo de estratégias podem ajudar a fazê-lo e como as tutoras e os estudantes se comportam no contexto prático. foi adotado um enfoque qualitativo de cunho etnográfico em que participaram 27 estudantes e 15 tutores de três centros de saúde que haviam recebido formação específica sobre tutoria clínica reflexiva. A análise foi realizada por meio de comparações constantes das categorias. os resultados demonstram que o uso de estratégias reflexivas como a interrogação didática, a empatia didática e o silêncio pedagógico por parte das tutoras, contribui para fomentar a reflexão do estudante e sua aprendizagem significativa. a prática reflexiva é a chave para a formação dos tutores e para a aprendizagem dos estudantes. analizar si el uso de estrategias reflexivas por parte de la tutora de prácticas clínicas fomenta la reflexión en los estudiantes. Se trata de conocer qué tipo de estrategias pueden ayudar a hacerlo y cómo se comportan tutoras y estudiantes en el contexto práctico. se ha utilizado un enfoque

Time stretch and its applications

Science.gov (United States)

Mahjoubfar, Ata; Churkin, Dmitry V.; Barland, Stéphane; Broderick, Neil; Turitsyn, Sergei K.; Jalali, Bahram

2017-06-01

Observing non-repetitive and statistically rare signals that occur on short timescales requires fast real-time measurements that exceed the speed, precision and record length of conventional digitizers. Photonic time stretch is a data acquisition method that overcomes the speed limitations of electronic digitizers and enables continuous ultrafast single-shot spectroscopy, imaging, reflectometry, terahertz and other measurements at refresh rates reaching billions of frames per second with non-stop recording spanning trillions of consecutive frames. The technology has opened a new frontier in measurement science unveiling transient phenomena in nonlinear dynamics such as optical rogue waves and soliton molecules, and in relativistic electron bunching. It has also created a new class of instruments that have been integrated with artificial intelligence for sensing and biomedical diagnostics. We review the fundamental principles and applications of this emerging field for continuous phase and amplitude characterization at extremely high repetition rates via time-stretch spectral interferometry.

EFFECTS OF DYNAMIC AND STATIC STRETCHING WITHIN GENERAL AND ACTIVITY SPECIFIC WARM-UP PROTOCOLS

Directory of Open Access Journals (Sweden)

Michael Samson

2012-06-01

Full Text Available The purpose of the study was to determine the effects of static and dynamic stretching protocols within general and activity specific warm-ups. Nine male and ten female subjects were tested under four warm-up conditions including a 1 general aerobic warm-up with static stretching, 2 general aerobic warm-up with dynamic stretching, 3 general and specific warm-up with static stretching and 4 general and specific warm-up with dynamic stretching. Following all conditions, subjects were tested for movement time (kicking movement of leg over 0.5 m distance, countermovement jump height, sit and reach flexibility and 6 repetitions of 20 metre sprints. Results indicated that when a sport specific warm-up was included, there was an 0.94% improvement (p = 0.0013 in 20 meter sprint time with both the dynamic and static stretch groups. No such difference in sprint performance between dynamic and static stretch groups existed in the absence of the sport specific warm-up. The static stretch condition increased sit and reach range of motion (ROM by 2.8% more (p = 0.0083 than the dynamic condition. These results would support the use of static stretching within an activity specific warm-up to ensure maximal ROM along with an enhancement in sprint performance

Propranolol, but not naloxone, enhances spinal reflex bladder activity and reduces pudendal inhibition in cats.

Science.gov (United States)

Rogers, Marc J; Xiao, Zhiying; Shen, Bing; Wang, Jicheng; Schwen, Zeyad; Roppolo, James R; de Groat, William C; Tai, Changfeng

2015-01-01

This study examined the role of β-adrenergic and opioid receptors in spinal reflex bladder activity and in the inhibition induced by pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS). Spinal reflex bladder contractions were induced by intravesical infusion of 0.25% acetic acid in α-chloralose-anesthetized cats after an acute spinal cord transection (SCT) at the thoracic T9/T10 level. PNS or TNS at 5 Hz was applied to inhibit these spinal reflex contractions at 2 and 4 times the threshold intensity (T) for inducing anal or toe twitch, respectively. During a cystrometrogram (CMG), PNS at 2T and 4T significantly (P reflex bladder contractions. After administering propranolol (3 mg/kg iv, a β₁/β₂-adrenergic receptor antagonist), the effects of 2T and 4T PNS on bladder capacity were significantly (P reflex bladder contractions or PNS inhibition. At the end of experiments, hexamethonium (10 mg/kg iv, a ganglionic blocker) significantly (P reflex bladder contractions. This study indicates an important role of β₁/β₂-adrenergic receptors in pudendal inhibition and spinal reflex bladder activity. Copyright © 2015 the American Physiological Society.

The medial olivocochlear reflex in children during active listening.

Science.gov (United States)

Smith, Spencer B; Cone, Barbara

2015-08-01

To determine if active listening modulates the strength of the medial olivocochlear (MOC) reflex in children. Click-evoked otoacoustic emissions (CEOAEs) were recorded from the right ear in quiet and in four test conditions: one with contralateral broadband noise (BBN) only, and three with active listening tasks wherein attention was directed to speech embedded in contralateral BBN. Fifteen typically-developing children (ranging in age from 8 to14 years) with normal hearing. CEOAE levels were reduced in every condition with contralateral acoustic stimulus (CAS) when compared to preceding quiet conditions. There was an additional systematic decrease in CEOAE level with increased listening task difficulty, although this effect was very small. These CEOAE level differences were most apparent in the 8-18 ms region after click onset. Active listening may change the strength of the MOC reflex in children, although the effects reported here are very subtle. Further studies are needed to verify that task difficulty modulates the activity of the MOC reflex in children.

Single Canonical Model of Reflexive Memory and Spatial Attention

Science.gov (United States)

Patel, Saumil S.; Red, Stuart; Lin, Eric; Sereno, Anne B.

2015-01-01

Many neurons in the dorsal and ventral visual stream have the property that after a brief visual stimulus presentation in their receptive field, the spiking activity in these neurons persists above their baseline levels for several seconds. This maintained activity is not always correlated with the monkey’s task and its origin is unknown. We have previously proposed a simple neural network model, based on shape selective neurons in monkey lateral intraparietal cortex, which predicts the valence and time course of reflexive (bottom-up) spatial attention. In the same simple model, we demonstrate here that passive maintained activity or short-term memory of specific visual events can result without need for an external or top-down modulatory signal. Mutual inhibition and neuronal adaptation play distinct roles in reflexive attention and memory. This modest 4-cell model provides the first simple and unified physiologically plausible mechanism of reflexive spatial attention and passive short-term memory processes. PMID:26493949

Single Canonical Model of Reflexive Memory and Spatial Attention.

Science.gov (United States)

Patel, Saumil S; Red, Stuart; Lin, Eric; Sereno, Anne B

2015-10-23

Many neurons in the dorsal and ventral visual stream have the property that after a brief visual stimulus presentation in their receptive field, the spiking activity in these neurons persists above their baseline levels for several seconds. This maintained activity is not always correlated with the monkey's task and its origin is unknown. We have previously proposed a simple neural network model, based on shape selective neurons in monkey lateral intraparietal cortex, which predicts the valence and time course of reflexive (bottom-up) spatial attention. In the same simple model, we demonstrate here that passive maintained activity or short-term memory of specific visual events can result without need for an external or top-down modulatory signal. Mutual inhibition and neuronal adaptation play distinct roles in reflexive attention and memory. This modest 4-cell model provides the first simple and unified physiologically plausible mechanism of reflexive spatial attention and passive short-term memory processes.

A reflexive perspective in problem solving

OpenAIRE

Chio, José Angel; Álvarez, Aida; López, Margarita

2013-01-01

The objective of this paper is to favour the methodological process of reflexive analysis in problem solving in the general teaching methods that concentrates in strengthening the dimensional analysis, to gain a greater preparation of the students for the solution of mathematical problems.

Contact of a spherical probe with a stretched rubber substrate

Science.gov (United States)

Frétigny, Christian; Chateauminois, Antoine

2017-07-01

We report on a theoretical and experimental investigation of the normal contact of stretched neo-Hookean substrates with rigid spherical probes. Starting from a published formulation of surface Green's function for incremental displacements on a prestretched, neo-Hookean, substrate [J. Mech. Phys. Solids 56, 2957 (2008), 10.1016/j.jmps.2008.07.002], a model is derived for both adhesive and nonadhesive contacts. The shape of the elliptical contact area together with the contact load and the contact stiffness are predicted as a function of the in-plane stretch ratios λx and λy of the substrate. The validity of this model is assessed by contact experiments carried out using an uniaxally stretched silicone rubber. For stretch ratio below about 1.25, a good agreement is observed between theory and experiments. Above this threshold, some deviations from the theoretical predictions are induced as a result of the departure of the mechanical response of the silicone rubber from the neo-Hokeean description embedded in the model.

Periostin inhibits mechanical stretch-induced apoptosis in osteoblast-like MG-63 cells.

Science.gov (United States)

Yu, Kai-Wen; Yao, Chung-Chen; Jeng, Jiiang-Huei; Shieh, Hao-Ying; Chen, Yi-Jane

2018-04-01

Appropriate mechanical stress plays an important role in regulating the proliferation and differentiation of osteoblasts, whereas high-level mechanical stress may be harmful and compromise cell survival. Periostin, a matricellular protein, is essential in maintaining functional integrity of bone and collagen-rich connective tissue in response to mechanical stress. This study investigated whether or not high-level mechanical stretch induces cell apoptosis and the regulatory role of periostin in mechanical stretch-induced apoptosis in osteoblastic cells. Osteoblast-like MG-63 cells were seeded onto Bio-Flex I culture plates and subjected to cyclic mechanical stretching (15% elongation, 0.1 Hz) in a Flexercell tension plus system-5000. The same process was applied to cells pre-treated with exogenous human recombinant periostin before mechanical stretching. We used a chromatin condensation and membrane permeability dead cell apoptosis kit to evaluate the stretch-induced cell responses. Expression of caspase-3 and cPARP was examined by immunofluorescent stain and flow cytometry. The expression of periostin in MG-63 cells is involved in the TGF-β signaling pathway. High-level cyclic mechanical stretch induced apoptotic responses in MG-63 osteoblastic cells. The percentages of apoptotic cells and cells expressing cPARP protein increased in the groups of cells subjected to mechanical stretch, but these responses were absent in the presence of exogenous periostin. Our study revealed that high-level mechanical stretch induces apoptotic cell death, and that periostin plays a protective role against mechanical stretch-induced apoptosis in osteoblastic cells. Copyright © 2017. Published by Elsevier B.V.

Human investigations into the exercise pressor reflex

DEFF Research Database (Denmark)

Secher, Niels H; Amann, Markus

2012-01-01

During exercise, neural input from skeletal muscles reflexly maintains or elevates blood pressure (BP) despite a maybe fivefold increase in vascular conductance. This exercise pressor reflex is illustrated by similar heart rate (HR) and BP responses to electrically induced and voluntary exercise....... The importance of the exercise pressor reflex for tight cardiovascular regulation during dynamic exercise is supported by studies using pharmacological blockade of lower limb muscle afferent nerves. These experiments show attenuation of the increase in BP and cardiac output when exercise is performed...... with attenuated neural feedback. Additionally, there is no BP response to electrically induced exercise with paralysing epidural anaesthesia or when similar exercise is evoked in paraplegic patients. Furthermore, BP decreases when electrically induced exercise is carried out in tetraplegic patients. The lack...

Force encoding in muscle spindles during stretch of passive muscle.

Directory of Open Access Journals (Sweden)

Kyle P Blum

2017-09-01

Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

Force encoding in muscle spindles during stretch of passive muscle.

Science.gov (United States)

Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

2017-09-01

Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

Stretch activates human myometrium via ERK, caldesmon and focal adhesion signaling.

Directory of Open Access Journals (Sweden)

Yunping Li

2009-10-01

Full Text Available An incomplete understanding of the molecular mechanisms responsible for myometrial activation from the quiescent pregnant state to the active contractile state during labor has hindered the development of effective therapies for preterm labor. Myometrial stretch has been implicated clinically in the initiation of labor and the etiology of preterm labor, but the molecular mechanisms involved in the human have not been determined. We investigated the mechanisms by which gestation-dependent stretch contributes to myometrial activation, by using human uterine samples from gynecologic hysterectomies and Cesarean sections. Here we demonstrate that the Ca requirement for activation of the contractile filaments in human myometrium increases with caldesmon protein content during gestation and that an increase in caldesmon phosphorylation can reverse this inhibitory effect during labor. By using phosphotyrosine screening and mass spectrometry of stretched human myometrial samples, we identify 3 stretch-activated focal adhesion proteins, FAK, p130Cas, and alpha actinin. FAK-Y397, which signals integrin engagement, is constitutively phosphorylated in term human myometrium whereas FAK-Y925, which signals downstream ERK activation, is phosphorylated during stretch. We have recently identified smooth muscle Archvillin (SmAV as an ERK regulator. A newly produced SmAV-specific antibody demonstrates gestation-specific increases in SmAV protein levels and stretch-specific increases in SmAV association with focal adhesion proteins. Thus, whereas increases in caldesmon levels suppress human myometrium contractility during pregnancy, stretch-dependent focal adhesion signaling, facilitated by the ERK activator SmAV, can contribute to myometrial activation. These results suggest that focal adhesion proteins may present new targets for drug discovery programs aimed at regulation of uterine contractility.

Optical tweezers stretching of chromatin

NARCIS (Netherlands)

Pope, L.H.; Bennink, Martin L.; Greve, Jan

2003-01-01

Recently significant success has emerged from exciting research involving chromatin stretching using optical tweezers. These experiments, in which a single chromatin fibre is attached by one end to a micron-sized bead held in an optical trap and to a solid surface or second bead via the other end,

Stretching Diagnostics and Mixing Properties In The Stratosphere

Science.gov (United States)

Legras, B.; Shuckburgh, E.

The "finite size Lyapunov exponent" and the "effective diffusivity" are two diagnos- tics of mixing which have been recently introduced to investigate atmospheric flows. Both have been used to successfully identify the barriers to transport, for instance at the edge of the stratospheric polar vortex. Here we compare the two diagnostics in detail. The equivalent length has the advantage of arising as a mixing quantification from a rigid theoretical framework, however it has the disadvantage of being an aver- age quantity (the average around a tracer contour). The finite size Lyapunov exponent may be defined at any point in the flow, and quantifies the stretching properties expe- rienced by a fluid parcel both in its past and future evolution. In particular, the lines of maximum stretching at any time delineate the building blocks of the chaotic stirring. However the interpretation of the finite size Lyapunov exponent as a mixing time is less direct and depends on the alignment of tracer contours with the stretching lines.

Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1.

Science.gov (United States)

Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

2015-02-01

Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30-50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40-50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30-40% in tension developing muscle but did not affect contraction-stimulated glucose transport in

Possible stretched exponential parametrization for humidity absorption in polymers.

Science.gov (United States)

Hacinliyan, A; Skarlatos, Y; Sahin, G; Atak, K; Aybar, O O

2009-04-01

Polymer thin films have irregular transient current characteristics under constant voltage. In hydrophilic and hydrophobic polymers, the irregularity is also known to depend on the humidity absorbed by the polymer sample. Different stretched exponential models are studied and it is shown that the absorption of humidity as a function of time can be adequately modelled by a class of these stretched exponential absorption models.

Hypnotizability, hypnosis and prepulse inhibition of the startle reflex in healthy women: an ERP analysis.

Directory of Open Access Journals (Sweden)

Vilfredo De Pascalis

Full Text Available A working model of the neurophysiology of hypnosis suggests that highly hypnotizable individuals (HHs have more effective frontal attentional systems implementing control, monitoring performance, and inhibiting unwanted stimuli from conscious awareness, than low hypnotizable individuals (LHs. Recent studies, using prepulse inhibition (PPI of the auditory startle reflex (ASR, suggest that HHs, in the waking condition, may show reduced sensory gating although they may selectively attend and disattend different stimuli. Using a within subject design and a strict subject selection procedure, in waking and hypnosis conditions we tested whether HHs compared to LHs showed a significantly lower inhibition of the ASR and startle-related brain activity in both time and intracerebral source localization domains. HHs, as compared to LH participants, exhibited (a longer latency of the eyeblink startle reflex, (b reduced N100 responses to startle stimuli, and (c higher PPI of eyeblink startle and of the P200 and P300 waves. Hypnosis yielded smaller N100 waves to startle stimuli and greater PPI of this component than in the waking condition. sLORETA analysis revealed that, for the N100 (107 msec elicited during startle trials, HHs had a smaller activation in the left parietal lobe (BA2/40 than LHs. Auditory pulses of pulse-with prepulse trials in HHs yielded less activity of the P300 (280 msec wave than LHs, in the cingulate and posterior cingulate gyrus (BA23/31. The present results, on the whole, are in the opposite direction to PPI findings on hypnotizability previously reported in the literature. These results provide support to the neuropsychophysiological model that HHs have more effective sensory integration and gating (or filtering of irrelevant stimuli than LHs.

Process Parameter Identification in Thin Film Flows Driven by a Stretching Surface

Directory of Open Access Journals (Sweden)

Satyananda Panda

2014-01-01

Full Text Available The flow of a thin liquid film over a heated stretching surface is considered in this study. Due to a potential nonuniform temperature distribution on the stretching sheet, a temperature gradient occurs in the fluid which produces surface tension gradient at the free surface of the thin film. As a result, the free surface deforms and these deformations are advected by the flow in the stretching direction. This work focuses on the inverse problem of reconstructing the sheet temperature distribution and the sheet stretch rate from observed free surface variations. This work builds on the analysis of Santra and Dandapat (2009 who, based on the long-wave expansion of the Navier-Stokes equations, formulate a partial differential equation which describes the evolution of the thickness of a film over a nonisothermal stretched surface. In this work, we show that after algebraic manipulation of a discrete form of the governing equations, it is possible to reconstruct either the unknown temperature field on the sheet and hence the resulting heat transfer or the stretching rate of the underlying surface. We illustrate the proposed methodology and test its applicability on a range of test problems.

The acute effect of static and dynamic stretching during warm-ups on anaerobic performance in trained women

Directory of Open Access Journals (Sweden)

rouhollah haghshenas

2014-09-01

Full Text Available The purpose of this study was to investigate effects of static stretching, dynamic stretching and no stretching methods on power and speed in volleyball players. Therefore, Twenty-four volleyball players (height: 173.29 ± 7.81 m; mass: 62.12 ± 8.73 kg; age: 22.66 ± 4.02 years; experience: 3.27 ± 6.37 were tested for speed performance using the 20 meter sprint test and also for power using vertical jump test after static stretching, dynamic stretching and no stretching. The results analyzed using ANOVA showed that There was a significant increase in height jump after dynamic stretching against static stretching. But, there were no significant differences between no stretching and static stretching groups. In addition, there was a significant decrease in time 20 meter sprint after dynamic stretching against static stretching and no stretching groups. The results of this study suggest that it may be desirable for volleyball players to perform dynamic exercises before the performance of activities that require a high power output.

Primary reflex persistence in children with reading difficulties (dyslexia): a cross-sectional study.

Science.gov (United States)

McPhillips, Martin; Jordan-Black, Julie-Anne

2007-03-02

The primary reflex system emerges during fetal life and is inhibited during the first year after birth. Our aim was to examine the effects of persistence of this early neurological system on the attainment of core literacy skills in dyslexic and non-dyslexic poor readers. We assessed the prevalence of a persistent primary reflex in a cross-sectional, representative sample of children (n=739) aged 7-9 years old attending mainstream primary school in Northern Ireland using standardised educational tests, and a clinical diagnostic test for a primary reflex (the asymmetrical tonic neck reflex (ATNR)). Multiple regression analyses, involving all of the sample children, revealed that persistence of the ATNR was significantly predictive of attainments in reading (t=-8.34, pschooling, the attainment of core educational skills may be affected by the persistence of a brainstem mediated reflex system that should have been inhibited in the first year after birth. Furthermore, these findings suggest that dyslexia is not a distinct category of poor reading, and that it may be more valid to term all poor readers as dyslexic irrespective of IQ.

Stretch-dependent slow force response in isolated rabbit myocardium is Na+ dependent.

Science.gov (United States)

von Lewinski, Dirk; Stumme, Burkhard; Maier, Lars S; Luers, Claus; Bers, Donald M; Pieske, Burkert

2003-03-15

Stretch induces functional and trophic effects in mammalian myocardium via various signal transduction pathways. We tested stretch signal transduction on immediate and slow force response (SFR) in rabbit myocardium. Experiments were performed in isolated right ventricular muscles from adult rabbit hearts (37 degrees C, 1 Hz stimulation rate, bicarbonate-buffer). Muscles were rapidly stretched from 88% of optimal length (L88) to near optimal length (L98) for functional analysis. The resulting immediate and slow increases in twitch force (first phase and SFR, respectively) were assessed at reduced [Na+]o or without and with blockade of stretch activated ion channels (SACs), angiotensin-II (AT1) receptors, endothelin-A (ET(A)) receptors, Na+/H+-exchange (NHE1), reverse mode Na+/Ca2+-exchange (NCX), or Na+/K+-ATPase. The effects of stretch on sarcoplasmic reticulum Ca2+-load were characterized using rapid cooling contractures (RCCs). Intracellular pH was measured in BCECF-AM loaded muscles, and action potential duration (APD) was assessed using floating electrodes. On average, force increased to 216+/-8% of the pre-stretch value during the immediate phase, followed by a further increase to 273+/-10% during the SFR (n=81). RCCs significantly increased during SFR, whereas pH and APD did not change. Neither inhibition of SACs, AT1, or ET(A) receptors affected the stretch-dependent immediate phase nor SFR. In contrast, SFR was reduced by NHE inhibition and almost completely abolished by reduced [Na+]o or inhibition of reverse-mode NCX, whereas increased SFR was seen after raising [Na+]i by Na+/K+-ATPase inhibition. The data demonstrate the existence of a delayed, Na+- and Ca2+-dependent but pH and APD independent SFR to stretch in rabbit myocardium. This inotropic response appears to be independent of autocrine/paracrine AT1 or ET(A) receptor activation, but mediated through stretch-induced activation of NHE and reverse mode NCX.

Cortical tremor: a variant of cortical reflex myoclonus.

Science.gov (United States)

Ikeda, A; Kakigi, R; Funai, N; Neshige, R; Kuroda, Y; Shibasaki, H

1990-10-01

Two patients with action tremor that was thought to originate in the cerebral cortex showed fine shivering-like finger twitching provoked mainly by action and posture. Surface EMG showed relatively rhythmic discharge at a rate of about 9 Hz, which resembled essential tremor. However, electrophysiologic studies revealed giant somatosensory evoked potentials (SEPs) with enhanced long-loop reflex and premovement cortical spike by the jerk-locked averaging method. Treatment with beta-blocker showed no effect, but anticonvulsants such as clonazepam, valproate, and primidone were effective to suppress the tremor and the amplitude of SEPs. We call this involuntary movement "cortical tremor," which is in fact a variant of cortical reflex myoclonus.

Referred pain elicited by manual exploration of the lateral rectus muscle in chronic tension-type headache.

Science.gov (United States)

Fernández-de-Las-Peñas, César; Cuadrado, Maria Luz; Gerwin, Robert D; Pareja, Juan A

2009-01-01

To analyze the presence of referred pain elicited by manual examination of the lateral rectus muscle in patients with chronic tension-type headache (CTTH). A case-control blinded study. It has been found previously that the manual examination of the superior oblique muscle can elicit referred pain to the head in some patients with migraine or tension-type headache. However, a referred pain from other extraocular muscles has not been investigated. Fifteen patients with CTTH and 15 healthy subjects without headache history were included. A blinded assessor performed a manual examination focused on the search for myofascial trigger points (TrPs) in the right and left lateral rectus muscles. TrP diagnosis was made when there was referred pain evoked by maintained pressure on the lateral corner of the orbit (anatomical projection of the lateral rectus muscle) for 20 seconds, and increased referred pain while the subject maintained a medial gaze on the corresponding side (active stretching of the muscle) for 15 seconds. On each side, a 10-point numerical pain rate scale was used to assess the intensity of referred pain at both stages of the examination. Ten patients with CTTH (66.6%) had referred pain that satisfied TrPs diagnostic criteria, while only one healthy control (0.07%) reported referred pain upon the examination of the lateral rectus muscles (P < 0.001). The elicited referred pain was perceived as a deep ache located at the supraorbital region or the homolateral forehead. Pain was evoked on both sides in all subjects with TrPs, with no difference in pain intensity between the right and the left. The average pain intensity was significantly greater in the patient group (P < 0.001). All CTTH patients with referred pain recognized it as the frontal pain that they usually experienced during their headache attacks, which was consistent with active TrPs. In some patients with CTTH, the manual examination of lateral rectus muscle TrPs elicits a referred pain that

The effects of team reflexivity on psychological well-being in manufacturing teams.

Science.gov (United States)

Chen, Jingqiu; Bamberger, Peter A; Song, Yifan; Vashdi, Dana R

2018-04-01

While the impact of team reflexivity (a.k.a. after-event-reviews, team debriefs) on team performance has been widely examined, we know little about its implications on other team outcomes such as member well-being. Drawing from prior team reflexivity research, we propose that reflexivity-related team processes reduce demands, and enhance control and support. Given the centrality of these factors to work-based strain, we posit that team reflexivity, by affecting these factors, may have beneficial implications on 3 core dimensions of employee burnout, namely exhaustion, cynicism, and inefficacy (reduced personal accomplishment). Using a sample of 469 unskilled manufacturing workers employed in 73 production teams in a Southern Chinese factory, we implemented a time lagged, quasi-field experiment, with half of the teams trained in and executing an end-of-shift team debriefing, and the other half assigned to a control condition and undergoing periodic postshift team-building exercises. Our findings largely supported our hypotheses, demonstrating that relative to team members assigned to the control condition, those assigned to the reflexivity condition experienced a significant improvement in all 3 burnout dimensions over time. These effects were mediated by control and support (but not demands) and amplified as a function of team longevity. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Swedish Massage and Abnormal Reflexes of Children with Spastic Cerebral Palsy

Directory of Open Access Journals (Sweden)

Vida Alizad

2007-09-01

Full Text Available Objectives: Massage therapy is one of the most widely used complementary and alternative medicine therapies for children. This study was conducted to determine the effect of wedish massage on abnormal reflexes in children with spastic cerebral palsy (CP. Methods: This study was a single blind clinical trial conducted on forty children with spastic CP who were recruited from clinics of the University of Social Welfare & Rehabilitation Sciences. They were randomly assigned to intervention and control groups. The routine occupational therapy (OT techniques were performed during a 3 month-period in both groups. The intervention group also received Swedish massage for 30 minutes before every OT session. Primary, spinal, brain stem, midbrain, cortical and automatic reflexes were evaluated at the beginning of the study and 3 months later. The data analysis was done by parametric and nonparametric tests. Results: Finally, thirteen subjects in the intervention group and 14 subjects in the control group were remained and studied. The average ages in the intervention and control groups were 49.5 and 42.1 months respectively. There were no statistically significant differences in abnormal reflexes in the intervention group in comparison to the control (P>0.05. Discussion: Adding Swedish massage to traditional OT techniques had no significant effects on abnormal reflexes in children with spastic cerebral palsy. Evidently more research is required in order to completely reject the effects of Swedish massage on abnormal reflexes of children with CP.

Computer simulation model of reflex e-beam systems coupled to an external circuit

International Nuclear Information System (INIS)

Jungwirth, K.; Stavinoha, P.

1982-01-01

Dynamics of ions and relativistic electrons in various high-voltage reflexing systems (reflex diodes and triodes) was investigated numerically by means of 1 1/2-dimensional PIC simulation model OREBIA. Its perfected version OREBIA-REX also accounts for system coupling to an external power source circuit, thus yielding the currents and applied voltage self-consistently. Various modes of operation of reflex diode and triode were studied using both models. It is shown that neglecting the influence of the external circuit can lead to seve--re overestimation of both ion currents and electron accumulation rates. In coupled systems with ions repeated collapses of impedance due to electron-ion relaxation processes are observed. The current and voltage pulses calculated for several reflex diodes and triodes with and without ions are presented. (J.U.)

Effect of e-Cigarette Use on Cough Reflex Sensitivity.

Science.gov (United States)

Dicpinigaitis, Peter V; Lee Chang, Alfredo; Dicpinigaitis, Alis J; Negassa, Abdissa

2016-01-01

E-cigarettes (e-cigs) have attained widespread popularity, yet knowledge of their physiologic effects remains minimal. The aim of this study was to evaluate the effect of a single exposure to e-cig vapor on cough reflex sensitivity. Thirty healthy nonsmokers underwent cough reflex sensitivity measurement using capsaicin cough challenge at baseline, 15 min, and 24 h after e-cig exposure (30 puffs 30 s apart). The end point of cough challenge is the concentration of capsaicin inducing five or more coughs (C5). The number of coughs induced by each e-cig inhalation was counted. A subgroup of subjects (n = 8) subsequently underwent an identical protocol with a non-nicotine-containing e-cig. Cough reflex sensitivity was significantly inhibited (C5 increased) 15 min after e-cig use (?0.29; 95% CI, ?0.43 to ?0.15; P < .0001); 24 h later, C5 returned to baseline (0.24; 95% CI, 0.10-0.38; P = .0002 vs post-15-min value). A subgroup of eight subjects demonstrating the largest degree of cough reflex inhibition had no suppression after exposure to a non-nicotine-containing e-cig (P = .0078 for comparison of ?C5 after nicotine vs non-nicotine device). Furthermore, more coughing was induced by the nicotine-containing vs non-nicotine-containing device (P = .0156). A single session of e-cig use, approximating nicotine exposure of one tobacco cigarette, induces significant inhibition of cough reflex sensitivity. Exploratory analysis of a subgroup of subjects suggests that nicotine is responsible for this observation. Our data, consistent with previous studies of nicotine effect, suggest a dual action of nicotine: an immediate, peripheral protussive effect and a delayed central antitussive effect. ClinicalTrials.gov; No.: NCT02203162; URL: www.clinicaltrials.gov. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Dynamics and structure of stretched flames

Energy Technology Data Exchange (ETDEWEB)

Law, C.K. [Princeton Univ., NJ (United States)

1993-12-01

This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

Excluded Volume Effects in Gene Stretching

OpenAIRE

Lam, Pui-Man

2002-01-01

We investigate the effects excluded volume on the stretching of a single DNA in solution. We find that for small force F, the extension h is not linear in F but proportion to F^{\\chi}, with \\chi=(1-\

Role of spinal metabotropic glutamate receptor 5 in pudendal inhibition of the nociceptive bladder reflex in cats.

Science.gov (United States)

Reese, Jeremy N; Rogers, Marc J; Xiao, Zhiying; Shen, Bing; Wang, Jicheng; Schwen, Zeyad; Roppolo, James R; de Groat, William C; Tai, Changfeng

2015-04-15

This study examined the role of spinal metabotropic glutamate receptor 5 (mGluR5) in the nociceptive C-fiber afferent-mediated spinal bladder reflex and in the inhibtion of this reflex by pudendal nerve stimulation (PNS). In α-chloralose-anesthetized cats after spinal cord transection at the T9/T10 level, intravesical infusion of 0.25% acetic acid irritated the bladder, activated nociceptive C-fiber afferents, and induced spinal reflex bladder contractions of low amplitude (reflexes were responsible for a major component of the contractions. This study shows that spinal mGluR5 plays an important role in the nociceptive C-fiber afferent-mediated spinal bladder reflex and in pudendal inhibition of this spinal reflex. Copyright © 2015 the American Physiological Society.

Stretched versus compressed exponential kinetics in α-helix folding

International Nuclear Information System (INIS)

Hamm, Peter; Helbing, Jan; Bredenbeck, Jens

2006-01-01

In a recent paper (J. Bredenbeck, J. Helbing, J.R. Kumita, G.A. Woolley, P. Hamm, α-helix formation in a photoswitchable peptide tracked from picoseconds to microseconds by time resolved IR spectroscopy, Proc. Natl. Acad. Sci USA 102 (2005) 2379), we have investigated the folding of a photo-switchable α-helix with a kinetics that could be fit by a stretched exponential function exp(-(t/τ) β ). The stretching factor β became smaller as the temperature was lowered, a result which has been interpreted in terms of activated diffusion on a rugged energy surface. In the present paper, we discuss under which conditions diffusion problems occur with stretched exponential kinetics (β 1). We show that diffusion problems do have a strong tendency to yield stretched exponential kinetics, yet, that there are conditions (strong perturbation from equilibrium, performing the experiment in the folding direction) under which compressed exponential kinetics would be expected instead. We discuss the kinetics on free energy surfaces predicted by simple initiation-propagation models (zipper models) of α-helix folding, as well as by folding funnel models. We show that our recent experiment has been performed under condition for which models with strong downhill driving force, such as the zipper model, would predict compressed, rather than stretched exponential kinetics, in disagreement with the experimental observation. We therefore propose that the free energy surface along a reaction coordinate that governs the folding kinetics must be relatively flat and has a shape similar to a 1D golf course. We discuss how this conclusion can be unified with the thermodynamically well established zipper model by introducing an additional kinetic reaction coordinate

Modulation of cardiopulmonary depressor reflex in nucleus ambiguus by electroacupuncture: roles of opioids and γ-aminobutyric acid.

Science.gov (United States)

Tjen-A-Looi, Stephanie C; Li, Peng; Li, Min; Longhurst, John C

2012-04-01

Stimulation of cardiopulmonary receptors with phenylbiguanide (PBG) elicits depressor cardiovascular reflex responses, including decreases in blood pressure and heart rate mediated in part by the brain stem parasympathetic cardiac neurons in the nucleus ambiguus (NAmb). The present study examined NAmb neurotransmitter mechanisms underlying the influence of electroacupuncture (EA) on the PBG-induced hypotension and bradycardia. We hypothesized that somatic stimulation during EA modulates PBG responses through opioid and γ-aminobutyric acid (GABA) modulation in the NAmb. Anesthetized and ventilated cats were studied during repeated stimulation with PBG or cardiac vagal afferents while low-frequency EA (2 Hz) was applied at P5-6 acupoints overlying the median nerve for 30 min and NAmb neuronal activity, heart rate, and blood pressure were recorded. Microinjection of kainic acid into the NAmb attenuated the PBG-induced bradycardia from -60 ± 11 to -36 ± 11 beats/min. Likewise, EA reduced the PBG-induced depressor and bradycardia reflex by 52 and 61%, respectively. Cardiac vagal afferent evoked preganglionic cellular activity in the NAmb was reduced by EA for about 60 min. Blockade of opioid or GABA(A) receptors using naloxone and gabazine reversed the EA-related modulation of the evoked cardiac vagal activity by 73 and 53%, respectively. Similarly, naloxone and gabazine reversed EA modulation of the negative chronotropic responses from -11 ± 5 to -23 ± 6 and -13 ± 4 to -24 ± 3 beats/min, respectively. Thus EA at P5-6 decreases PBG evoked hypotension and bradycardia as well as the NAmb PBG-sensitive preganglionic cardiac vagal outflow through opioid and GABA neurotransmitter systems.

Effect of Twisting and Stretching on Magneto Resistance and Spin Filtration in CNTs

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Anil Kumar Singh

2017-08-01

Full Text Available Spin-dependent quantum transport properties in twisted carbon nanotube and stretched carbon nanotube are calculated using density functional theory (DFT and non-equilibrium green’s function (NEGF formulation. Twisting and stretching have no effect on spin transport in CNTs at low bias voltages. However, at high bias voltages the effects are significant. Stretching restricts any spin-up current in antiparallel configuration (APC, which results in higher magneto resistance (MR. Twisting allows spin-up current almost equivalent to the pristine CNT case, resulting in lower MR. High spin filtration is observed in PC and APC for pristine, stretched and twisted structures at all applied voltages. In APC, at low voltages spin filtration in stretched CNT is higher than in pristine and twisted ones, with pristine giving a higher spin filtration than twisted CNT.

Reflexive journaling on emotional research topics: ethical issues for team researchers.

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Malacrida, Claudia

2007-12-01

Traditional epistemological concerns in qualitative research focus on the effects of researchers' values and emotions on choices of research topics, power relations with research participants, and the influence of researcher standpoints on data collection and analysis. However, the research process also affects the researchers' values, emotions, and standpoints. Drawing on reflexive journal entries of assistant researchers involved in emotionally demanding team research, this article explores issues of emotional fallout for research team members, the implications of hierarchical power imbalances on research teams, and the importance of providing ethical opportunities for reflexive writing about the challenges of doing emotional research. Such reflexive approaches ensure the emotional safety of research team members and foster opportunities for emancipatory consciousness among research team members.

Effect of Ankle Positioning During Hamstring Stretches for Improving Straight Leg Hip Flexion Motion.

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Laudner, Kevin G; Benjamin, Peter J; Selkow, Noelle M

2016-03-01

To compare the effects of stretching the hamstrings with the ankle in either a plantar-flexed (PF) or dorsiflexed (DF) position for improving straight leg hip flexion range of motion (ROM) over a 4-week period. Randomized, single-blinded, pretest, posttest design. Athletic training facility. Each limb of 34 asymptomatic individuals (15 males, 19 females) was randomly assigned to one of the 3 groups. Twenty-four limbs received hamstring stretches with the ankle in DF, 24 limbs received hamstring stretches with the ankle in PF, and 20 limbs received no stretch (control). Ankle position (PF, DF) during hamstring stretching. We measured pretest and posttest passive straight leg hip flexion ROM with the test ankle in a neutral position. For the intervention groups, the test limb was passively stretched with the ankle held in end range DF or PF for their respective group. Each stretch was held for 30 seconds for a total of 3 applications. Two treatment sessions were completed per week for a total of 4 weeks. The control limbs received no stretching during the 4-week period. We conducted 1-way analyses of covariance to determine significant changes in ROM between groups (P hamstrings in either PF or DF improve straight leg hip ROM compared with a control group. The results of this study should be considered by clinicians when determining the optimal stretching techniques aimed at increasing hamstring length.

Acute Effect of Different Combined Stretching Methods on Acceleration and Speed in Soccer Players

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Amiri-Khorasani Mohammadtaghi

2016-04-01

Full Text Available The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up, on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height: 177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49 years was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min stretching program (except for the no-stretching protocol, and 2 min rest periods, followed by the 10 and 20 m sprint test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic stretching compared with static, combined, and no-stretching protocols. There were also significant differences between the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more force for a faster execution.

Flow of viscous fluid along an exponentially stretching curved surface

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N.F. Okechi

Full Text Available In this paper, we present the boundary layer analysis of flow induced by rapidly stretching curved surface with exponential velocity. The governing boundary value problem is reduced into self-similar form using a new similarity transformation. The resulting equations are solved numerically using shooting and Runge-Kutta methods. The numerical results depicts that the fluid velocity as well as the skin friction coefficient increases with the surface curvature, similar trend is also observed for the pressure. The dimensionless wall shear stress defined for this problem is greater than that of a linearly stretching curved surface, but becomes comparably less for a surface stretching with a power-law velocity. In addition, the result for the plane surface is a special case of this study when the radius of curvature of the surface is sufficiently large. The numerical investigations presented in terms of the graphs are interpreted with the help of underlying physics of the fluid flow and the consequences arising from the curved geometry. Keywords: Boundary layer flow, Curved surface, Exponential stretching, Curvature

How Can Hypnodontics Manage Severe Gag Reflex for Root Canal Therapy? A Case Report

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Ramazani, Mohsen; zarenejad, Nafiseh; Parirokh, Masoud; Zahedpasha, Samir

2016-01-01

In endodontics, severe involuntary gagging can have a severe impact on treatment procedure. There are many ways to ease the gag reflex, one of which is hypnosis. A 34-year-old male was referred for root canal treatment of a molar tooth. He had not received any dental treatments for the past nine years due to fear of severe gag reflex. Three hypnotic sessions based upon eye fixation, progressive muscle relaxation and guided imagery techniques were spent for psychosomatic management. The gag reflex was controlled and reduced to a normal level, and the required dental treatments including root canal therapy and restoration were performed successfully. This report shows that hypnosis can control gag reflex for dental treatments. PMID:27141226

Directional Cell Migration in Response to Repeated Substratum Stretching

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Okimura, Chika; Iwadate, Yoshiaki

2017-10-01

Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

Educational Strategies to Enhance Reflexivity Among Clinicians and Health Professional Students: A Scoping Study

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Rachel Landy

2016-09-01

Full Text Available Reflexivity involves the ability to understand how one's social locations and experiences of advantage or disadvantage have shaped the way one understands the world. The capacity for reflexivity is crucial because it informs clinical decisions, which can lead to improvements in service delivery and patient outcomes. In this article, we present a scoping study that explored educational strategies designed to enhance reflexivity among clinicians and/or health profession students. We reviewed articles and grey literature that address the question: What is known about strategies for enhancing reflexivity among clinicians and students in health professional training programs? We searched multiple databases using keywords including: reflexivity, reflective, allied health professionals, pedagogy, learning, and education. The search strategy was iterative and involved three reviews. Each abstract was independently reviewed by two team members. Sixty-eight texts met the inclusion criteria. There was great diversity among the educational strategies and among health professions. Commonalities across strategies were identified related to reflective writing, experiential learning, classroom-based activities, continuing education, and online learning. We also summarize the 19 texts that evaluated educational strategies to enhance reflexivity. Further research and education is urgently needed for more equitable and socially-just health care. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1603140

The Reflexive Nature of Reading as Ethnographic Practice: Editorial Note

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Wolff-Michael Roth

2004-01-01

Full Text Available In this editorial, I suggest that not only is reading published texts a way of doing ethno­graph­ic research, but also reading concretely realizes itself in the productions of new texts that reproduce the cultural practices that are analyzed in the published text. Reading as ethnographic method is therefore a reflexive project. I provide a dialectical framework for theorizing the reflexive nature of reading. URN: urn:nbn:de:0114-fqs0401390

Reversing Maladaptive Plasticity to Cure Autonomic Dysreflexia after Spinal Cord Injury

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2016-10-01

to elicit spinal autonomic reflexes as described previously [9]. The tips of Hartman hemostats were shielded with polyethylene tubing and then used...to the first click in every trial for 30 s. Colorectal distension was accomplished using a 4-French, 60 mm balloon- tipped catheter (Swan-Ganz...distension were used to elicit somatic or visceral-sympathetic reflexes below the level of injury. Such stimuli are potent induces of autonomic

Reflex control of the spine and posture: a review of the literature from a chiropractic perspective

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Schlappi Mark

2005-08-01

Full Text Available Abstract Objective This review details the anatomy and interactions of the postural and somatosensory reflexes. We attempt to identify the important role the nervous system plays in maintaining reflex control of the spine and posture. We also review, illustrate, and discuss how the human vertebral column develops, functions, and adapts to Earth's gravity in an upright position. We identify functional characteristics of the postural reflexes by reporting previous observations of subjects during periods of microgravity or weightlessness. Background Historically, chiropractic has centered around the concept that the nervous system controls and regulates all other bodily systems; and that disruption to normal nervous system function can contribute to a wide variety of common ailments. Surprisingly, the chiropractic literature has paid relatively little attention to the importance of neurological regulation of static upright human posture. With so much information available on how posture may affect health and function, we felt it important to review the neuroanatomical structures and pathways responsible for maintaining the spine and posture. Maintenance of static upright posture is regulated by the nervous system through the various postural reflexes. Hence, from a chiropractic standpoint, it is clinically beneficial to understand how the individual postural reflexes work, as it may explain some of the clinical presentations seen in chiropractic practice. Method We performed a manual search for available relevant textbooks, and a computer search of the MEDLINE, MANTIS, and Index to Chiropractic Literature databases from 1970 to present, using the following key words and phrases: "posture," "ocular," "vestibular," "cervical facet joint," "afferent," "vestibulocollic," "cervicocollic," "postural reflexes," "spaceflight," "microgravity," "weightlessness," "gravity," "posture," and "postural." Studies were selected if they specifically tested any or

Parasympathetic Nervous System Dysfunction, as Identified by Pupil Light Reflex, and Its Possible Connection to Hearing Impairment.

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Yang Wang

Full Text Available Although the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown.To 1 review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2 review the evidence relating hearing impairment and parasympathetic activity and 3 seek evidence of possible connections between hearing impairment and the pupil light reflex.Literature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment.Thirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment.As the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing

Parasympathetic Nervous System Dysfunction, as Identified by Pupil Light Reflex, and Its Possible Connection to Hearing Impairment.

Science.gov (United States)

Wang, Yang; Zekveld, Adriana A; Naylor, Graham; Ohlenforst, Barbara; Jansma, Elise P; Lorens, Artur; Lunner, Thomas; Kramer, Sophia E

2016-01-01

Although the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown. To 1) review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2) review the evidence relating hearing impairment and parasympathetic activity and 3) seek evidence of possible connections between hearing impairment and the pupil light reflex. Literature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment. Thirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment. As the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing impairment

On prediction of OH stretching frequencies in intramolecularly hydrogen bonded systems

DEFF Research Database (Denmark)

Hansen, Poul Erik; Spanget-Larsen, Jens

2012-01-01

OH stretching frequencies are investigated for a series of non-tautomerizing systems with intramolecular hydrogen bonds. Effective OH stretching wavenumbers are predicted by the application of empirical correlation procedures based on the results of B3LYP/6-31G(d) theoretical calculations...

Optimization of path length stretching in Monte Carlo calculations for non-leakage problems

Energy Technology Data Exchange (ETDEWEB)

Hoogenboom, J.E. [Delft Univ. of Technology (Netherlands)

2005-07-01

Path length stretching (or exponential biasing) is a well known variance reduction technique in Monte Carlo calculations. It can especially be useful in shielding problems where particles have to penetrate a lot of material before being tallied. Several authors sought for optimization of the path length stretching parameter for detection of the leakage of neutrons from a slab. Here the adjoint function behaves as a single exponential function and can well be used to determine the stretching parameter. In this paper optimization is sought for a detector embedded in the system, which changes the adjoint function in the detector drastically. From literature it is known that the combination of path length stretching and angular biasing can result in appreciable variance reduction. However, angular biasing is not generally available in general purpose Monte Carlo codes and therefore we want to restrict ourselves to the application of pure path length stretching and finding optimum parameters for that. Nonetheless, the starting point for our research is the zero-variance scheme. In order to study the solution in detail the simplified monoenergetic two-direction model is adopted, which allows analytical solutions and can still be used in a Monte Carlo simulation. Knowing the zero-variance solution analytically, it is shown how optimum path length stretching parameters can be derived from it. It results in path length shrinking in the detector. Results for the variance in the detector response are shown in comparison with other patterns for the stretching parameter. The effect of anisotropic scattering on the path length stretching parameter is taken into account. (author)

Cyclic mechanical stretch enhances BMP9-induced osteogenic differentiation of mesenchymal stem cells.

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Song, Yang; Tang, Yinhong; Song, Jinlin; Lei, Mingxing; Liang, Panpan; Fu, Tiwei; Su, Xudong; Zhou, Pengfei; Yang, Li; Huang, Enyi

2018-04-01

The purpose of this study was to investigate whether mechanical stretch can enhance the bone morphogenetic protein 9 (BMP9)-induced osteogenic differentiation in MSCs. Recombinant adenoviruses were used to overexpress the BMP9 in C3H10T1/2 MSCs. Cells were seeded onto six-well BioFlex collagen I-coated plates and subjected to cyclic mechanical stretch [6% elongation at 60 cycles/minute (1 Hz)] in a Flexercell FX-4000 strain unit for up to 12 hours. Immunostaining and confocal microscope were used to detect cytoskeleton organization. Cell cycle progression was checked by flow cytometry. Alkaline phosphatase activity was measured with a Chemiluminescence Assay Kit and was quantified with a histochemical staining assay. Matrix mineralization was examined by Alizarin Red S Staining. Mechanical stretch induces cytoskeleton reorganization and inhibits cell proliferation by preventing cells entry into S phase of the cell cycle. Although mechanical stretch alone does not induce the osteogenic differentiation of C3H10T1/2 MSCs, co-stimulation with mechanical stretch and BMP9 enhances alkaline phosphatase activity. The expression of key lineage-specific regulators (e.g., osteocalcin (OCN), SRY-related HMG-box 9, and runt-related transcription factor 2) is also increased after the co-stimulation, compared to the mechanical stretch stimulation along. Furthermore, mechanical stretch augments the BMP9-mediated bone matrix mineralization of C3H10T1/2 MSCs. Our results suggest that mechanical stretch enhances BMP9-induced osteoblastic lineage specification in C3H10T1/2 MSCs.

Factitious lymphoedema as a psychiatric condition mimicking reflex sympathetic dystrophy: a case report

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Nwaejike Nnamdi

2008-06-01

Full Text Available Abstract Introduction Reflex sympathetic dystrophy can result in severe disability with only one in five patients able to fully resume prior activities. Therefore, it is important to diagnose this condition early and begin appropriate treatment. Factitious lymphoedema can mimic reflex sympathetic dystrophy and is caused by self-inflicted tourniquets, blows to the arm or repeated skin irritation. Patients with factitious lymphoedema have an underlying psychiatric disorder but usually present to emergency or orthopaedics departments. Factitious lymphoedema can then be misdiagnosed as reflex sympathetic dystrophy. The treatment for factitious lymphoedema is dealing with the underlying psychiatric condition. Case presentation We share our experience of treating a 33-year-old man, who presented with factitious lymphoedema, initially diagnosed as reflex sympathetic dystrophy. Conclusion Awareness of this very similar differential diagnosis allows early appropriate treatment to be administered.

Crustal Stretching Style and Lower Crust Flow of the South China Sea Northern Margin

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Bai, Y.; Dong, D.; Runlin, D.

2017-12-01

There is a controversy about crustal stretching style of the South China Sea (SCS) northern margin mainly due to considerable uncertainty of stretching factor estimation, for example, as much as 40% of upper crust extension (Walsh et al., 1991) would be lost by seismic profiles due to poor resolution. To discover and understand crustal stretching style and lower crustal flow on the whole, we map the Moho and Conrad geometries based on gravity inversion constrained by deep seismic profiles, then according to the assumption of upper and lower crust initial thickness, upper and lower crust stretching factors are estimated. According to the comparison between upper and lower crust stretching factors, the SCS northern margin could be segmented into three parts, (1) sediment basins where upper crust is stretched more than lower crust, (2) COT regions where lower crust is stretched more than upper crust, (3) other regions where the two layers have similar stretching factors. Stretching factor map shows that lower crust flow happened in both of COT and sediment basin regions where upper crust decouples with lower crust due to high temperature. Pressure contrast by sediment loading in basins and erosion in sediment-source regions will lead to lower crust flow away from sediment sink to source. Decoupled and fractured upper crust is stretched further by sediment loading and the following compensation would result in relatively thick lower crust than upper crust. In COT regions with thin sediment coverage, low-viscosity lower crust is easier to thin in extensional environment, also the lower crust tends to flow away induced by magma upwelling. Therefore, continental crust on the margin is not stretching in a constant way but varies with the tectonic setting changes. This work is supported by National Natural Science Foundation of China (Grant No. 41506055, 41476042) and Fundamental Research Funds for the Central Universities China (No.17CX02003A).

Maintained changes in motoneuronal excitability by short‐lasting synaptic inputs in the decerebrate cat

DEFF Research Database (Denmark)

Crone, C.; Hultborn, H.; Kiehn, O.

1988-01-01

1. During investigation of the tonic stretch reflex in the unanaesthetized decerebrate cat we observed that a short train of impulses in Ia afferents from the soleus muscle (or its synergists) may cause a prolonged activity in the soleus muscle as judged by EMG and tension recordings. This excita......1. During investigation of the tonic stretch reflex in the unanaesthetized decerebrate cat we observed that a short train of impulses in Ia afferents from the soleus muscle (or its synergists) may cause a prolonged activity in the soleus muscle as judged by EMG and tension recordings...

Common neural structures activated by epidural and transcutaneous lumbar spinal cord stimulation: Elicitation of posterior root-muscle reflexes.

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Ursula S Hofstoetter

Full Text Available Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diameter afferent fibers within lumbar and upper sacral posterior roots. Recent pilot studies suggested that the surface electrode-based method of transcutaneous spinal cord stimulation (SCS may produce similar neuromodulatory effects as caused by epidural SCS. Neurophysiological and computer modeling studies proposed that this noninvasive technique stimulates posterior-root fibers as well, likely activating similar input structures to the spinal cord as epidural stimulation. Here, we add a yet missing piece of evidence substantiating this assumption. We conducted in-depth analyses and direct comparisons of the electromyographic (EMG characteristics of short-latency responses in multiple leg muscles to both stimulation techniques derived from ten individuals with SCI each. Post-activation depression of responses evoked by paired pulses applied either epidurally or transcutaneously confirmed the reflex nature of the responses. The muscle responses to both techniques had the same latencies, EMG peak-to-peak amplitudes, and waveforms, except for smaller responses with shorter onset latencies in the triceps surae muscle group and shorter offsets of the responses in the biceps femoris muscle during epidural stimulation. Responses obtained in three subjects tested with both methods at different time points had near-identical waveforms per muscle group as well as same onset latencies. The present results strongly corroborate the activation of common neural input structures to the lumbar spinal cord-predominantly primary afferent fibers within multiple posterior roots-by both techniques and add to unraveling the

Sequence-length variation of mtDNA HVS-I C-stretch in Chinese ethnic groups.

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Chen, Feng; Dang, Yong-hui; Yan, Chun-xia; Liu, Yan-ling; Deng, Ya-jun; Fulton, David J R; Chen, Teng

2009-10-01

The purpose of this study was to investigate mitochondrial DNA (mtDNA) hypervariable segment-I (HVS-I) C-stretch variations and explore the significance of these variations in forensic and population genetics studies. The C-stretch sequence variation was studied in 919 unrelated individuals from 8 Chinese ethnic groups using both direct and clone sequencing approaches. Thirty eight C-stretch haplotypes were identified, and some novel and population specific haplotypes were also detected. The C-stretch genetic diversity (GD) values were relatively high, and probability (P) values were low. Additionally, C-stretch length heteroplasmy was observed in approximately 9% of individuals studied. There was a significant correlation (r=-0.961, Ppopulations. The results from the Fst and dA genetic distance matrix, neighbor-joining tree, and principal component map also suggest that C-stretch could be used as a reliable genetic marker in population genetics.

Team performance in the Italian NHS: the role of reflexivity.

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Urbini, Flavio; Callea, Antonino; Chirumbolo, Antonio; Talamo, Alessandra; Ingusci, Emanuela; Ciavolino, Enrico

2018-04-09

Purpose The purpose of this paper is twofold: first, to investigate the goodness of the input-process-output (IPO) model in order to evaluate work team performance within the Italian National Health Care System (NHS); and second, to test the mediating role of reflexivity as an overarching process factor between input and output. Design/methodology/approach The Italian version of the Aston Team Performance Inventory was administered to 351 employees working in teams in the Italian NHS. Mediation analyses with latent variables were performed via structural equation modeling (SEM); the significance of total, direct, and indirect effect was tested via bootstrapping. Findings Underpinned by the IPO framework, the results of SEM supported mediational hypotheses. First, the application of the IPO model in the Italian NHS showed adequate fit indices, showing that the process mediates the relationship between input and output factors. Second, reflexivity mediated the relationship between input and output, influencing some aspects of team performance. Practical implications The results provide useful information for HRM policies improving process dimensions of the IPO model via the mediating role of reflexivity as a key role in team performance. Originality/value This study is one of a limited number of studies that applied the IPO model in the Italian NHS. Moreover, no study has yet examined the role of reflexivity as a mediator between input and output factors in the IPO model.

Mechanical stretching stimulates collagen synthesis via down-regulating SO2/AAT1 pathway

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Liu, Jia; Yu, Wen; Liu, Yan; Chen, Selena; Huang, Yaqian; Li, Xiaohui; Liu, Cuiping; Zhang, Yanqiu; Li, Zhenzhen; Du, Jie; Tang, Chaoshu; Du, Junbao; Jin, Hongfang

2016-01-01

The aim of the study was to investigate the role of endogenous sulfur dioxide (SO2)/ aspartate aminotransferase 1 (AAT1) pathway in stretch-induced excessive collagen expression and its mechanism. The mechanical stretch downregulated SO2/AAT1 pathway and increased collagen I and III protein expression. Importantly, AAT1 overexpression blocked the increase in collagen I and III expression, transforming growth factor-β1 (TGF- β1) expression and phosphorylation of Smad2/3 induced by stretch, but AAT1 knockdown mimicked the increase in collagen I and III expression, TGF- β1 expression and phosphorylation of Smad2/3 induced by stretch. Mechanistically, SB431542, a TGF-β1/Smad2/3 inhibitor, eliminated excessive collagen I and III accumulation induced by AAT1 knockdown, stretch or stretch plus AAT1 knockdown. In a rat model of high pulmonary blood flow-induced pulmonary vascular collagen accumulation, AAT1 expression and SO2 content in lung tissues of rat were reduced in shunt rats with high pulmonary blood flow. Supplement of SO2 derivatives inhibited activation of TGF- β1/Smad2/3 pathway and alleviated the excessive collagen accumulation in lung tissues of shunt rats. The results suggested that deficiency of endogenous SO2/AAT1 pathway mediated mechanical stretch-stimulated abnormal collagen accumulation via TGF-β1/Smad2/3 pathway. PMID:26880260

Dynamic clinical measurements of voluntary vaginal contractions and autonomic vaginal reflexes.

Science.gov (United States)

Broens, Paul M A; Spoelstra, Symen K; Weijmar Schultz, Willibrord C M

2014-12-01

The vaginal canal is an active and responsive canal. It has pressure variations along its length and shows reflex activity. At present, the prevailing idea is that the vaginal canal does not have a sphincter mechanism. It is hypothesized that an active vaginal muscular mechanism exists and might be involved in the pathophysiology of genito-pelvic pain/penetration disorder. The aim of this study was to detect the presence of a canalicular vaginal "sphincter mechanism" by measuring intravaginal pressure at different levels of the vaginal canal during voluntary pelvic floor contractions and during induced reflexive contractions. Sixteen nulliparous women, without sexual dysfunction and pelvic floor trauma, were included in the study. High-resolution solid-state circumferential catheters were used to measure intravaginal pressures and vaginal contractions at different levels in the vaginal canal. Voluntary intravaginal pressure measurements were performed in the left lateral recumbent position only, while reflexive intravaginal pressure measurements during slow inflation of a vaginal balloon were performed in the left lateral recumbent position and in the sitting position. Intravaginal pressures and vaginal contractions were the main outcome measures. In addition, a general demographic and medical history questionnaire was administered to gain insight into the characteristics of the study population. Fifteen out of the sixteen women had deep and superficial vaginal high-pressure zones. In one woman, no superficial high-pressure zone was found. The basal and maximum pressures, as well as the duration of the autonomic reflexive contractions significantly exceeded the pressures and the duration of the voluntary contractions. There were no significant differences between the reflexive measurements obtained in the left lateral recumbent and the sitting position. The two high-pressure zones found in this study, as a result of voluntary contractions and, even more pronounced

DNA analysis by single molecule stretching in nanofluidic biochips

DEFF Research Database (Denmark)

Abad, E.; Juarros, A.; Retolaza, A.

2011-01-01

Imprint Lithography (NIL) technology combined with a conventional anodic bonding of the silicon base and Pyrex cover. Using this chip, we have performed single molecule imaging on a bench-top fluorescent microscope system. Lambda phage DNA was used as a model sample to characterize the chip. Single molecules of λ-DNA......Stretching single DNA molecules by confinement in nanofluidic channels has attracted a great interest during the last few years as a DNA analysis tool. We have designed and fabricated a sealed micro/nanofluidic device for DNA stretching applications, based on the use of the high throughput Nano...... stained with the fluorescent dye YOYO-1 were stretched in the nanochannel array and the experimental results were analysed to determine the extension factor of the DNA in the chip and the geometrical average of the nanochannel inner diameter. The determination of the extension ratio of the chip provides...

Effect of acute stretch injury on action potential and network activity of rat neocortical neurons in culture.

Science.gov (United States)

Magou, George C; Pfister, Bryan J; Berlin, Joshua R

2015-10-22

The basis for acute seizures following traumatic brain injury (TBI) remains unclear. Animal models of TBI have revealed acute hyperexcitablility in cortical neurons that could underlie seizure activity, but studying initiating events causing hyperexcitability is difficult in these models. In vitro models of stretch injury with cultured cortical neurons, a surrogate for TBI, allow facile investigation of cellular changes after injury but they have only demonstrated post-injury hypoexcitability. The goal of this study was to determine if neuronal hyperexcitability could be triggered by in vitro stretch injury. Controlled uniaxial stretch injury was delivered to a spatially delimited region of a spontaneously active network of cultured rat cortical neurons, yielding a region of stretch-injured neurons and adjacent regions of non-stretched neurons that did not directly experience stretch injury. Spontaneous electrical activity was measured in non-stretched and stretch-injured neurons, and in control neuronal networks not subjected to stretch injury. Non-stretched neurons in stretch-injured cultures displayed a three-fold increase in action potential firing rate and bursting activity 30-60 min post-injury. Stretch-injured neurons, however, displayed dramatically lower rates of action potential firing and bursting. These results demonstrate that acute hyperexcitability can be observed in non-stretched neurons located in regions adjacent to the site of stretch injury, consistent with reports that seizure activity can arise from regions surrounding the site of localized brain injury. Thus, this in vitro procedure for localized neuronal stretch injury may provide a model to study the earliest cellular changes in neuronal function associated with acute post-traumatic seizures. Copyright © 2015. Published by Elsevier B.V.

Medial olivocochlear reflex interneurons are located in the posteroventral cochlear nucleus: a kainic acid lesion study in guinea pigs.

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de Venecia, Ronald K; Liberman, M Charles; Guinan, John J; Brown, M Christian

2005-07-11

The medial olivocochlear (MOC) reflex arc is probably a three-neuron pathway consisting of type I spiral ganglion neurons, reflex interneurons in the cochlear nucleus, and MOC neurons that project to the outer hair cells of the cochlea. We investigated the identity of MOC reflex interneurons in the cochlear nucleus by assaying their regional distribution using focal injections of kainic acid. Our reflex metric was the amount of change in the distortion product otoacoustic emission (at 2f(1)-f(2)) just after onset of the primary tones. This metric for MOC reflex strength has been shown to depend on an intact reflex pathway. Lesions involving the posteroventral cochlear nucleus (PVCN), but not the other subdivisions, produced long-term decreases in MOC reflex strength. The degree of cell loss within the dorsal part of the PVCN was a predictor of whether the lesion affected MOC reflex strength. We suggest that multipolar cells within the PVCN have the distribution and response characteristics appropriate to be the MOC reflex interneurons. (c) 2005 Wiley-Liss, Inc.

Two Reflexivities in Current Social Science: Remarks on an Absent Debate

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Andreas Langenohl

2009-02-01

Full Text Available This paper traces and compares two different uses of the category of reflexivity in contemporary methodological debates in the social sciences. While a first use is strongly influenced by the textual turn in cultural anthropology, a second use is aligned with Pierre BOURDIEU's notion of "scientific reflexivity." Whereas the first use postulates an epistemological break with scientific modernity and argues for a perpetual contextualization and interrelation of research results and methods, BOURDIEU defends sociology’s claim of objectivity, which, according to him, can be redeemed through a reflexive objectification of sociological practice. Up to the present these two uses have existed in almost complete isolation from each other. They represent alternating reactions to, and reconstructions and translations of, poststructuralism and postmodernism in the social sciences. URN: urn:nbn:de:0114-fqs090297

Danish Working Environment Regulation. How reflexive - how political? -a Scandinavian case

DEFF Research Database (Denmark)

Koch, Christian

an understanding of the directions of the reforms made in this period. The paper operate with two analytical perspectives: The reflexive regulation perspective and the political process perspective. Danish working environment regulation is discussed through the general political initiatives taken, and through four...... specific regulation topics: The Occupational Health Services (OHS), regulation of the psychological working environment, the 'Monotonous Repeated Work'-plan and the workers' compensation. Taking the last twenty years' development as a whole the main developments in the regulation is a further shift...... in balance between material and reflexive regulation elements to the benefit of the latter. But although the reflexive elements seem to stabilize, they are vulnerable to a loss of legitimacy and changes in the political pattern.The impact on enterprise power patterns is summed up in a polarization thesis...

Reflexive Aero Structures for Enhanced Survivability, Phase II

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National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) will develop an advanced reflexive structure technology system to increase the survivability of future systems constructed of...

The Use of Restoring Resources of the Survival Roles and Reflex Patterns in MNRI® (Reflex Integration Interactive Training of Personality Growth and Interpersonal Relations

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Masgutova S.K.

2017-12-01

Full Text Available Personality growth as a socio-psychological problem is a multi-complex phenomenon that targets Self-identity, Self-actualization, and other areas. During the last decade scientists started studying other factors limiting the personality growth, such as stress and post-trauma. However, the Survival Roles, the socio-individual patterns based on neurophysiological and psychological defense mechanisms blocking the personality Self-actualization, social interaction and professional business qualities, are rarely discussed. Thus this study based on Survival Roles may extend the personality growth oriented concepts and therapy modality tools. This study showed a correlation between Survival Role patterns, stress resilience, and survival reflexes (integrative units of the nervous system functions. Comparative data on 464 business professionals from high management jobs (Study Group — n=340, and Control Group — n=124 participated in this research which found 70.9 % (n=329 of the total group was in stress. This stress activated socio-individual Survival Roles and protective reflex patterns which responded with reactivity, over-protection, non-constructive interactions with others and limited business strategies. The MNRI® reflex integrative training used in this study demonstrated improvement of functions of the protective reflex patterns effected positively the survival mechanisms including increased stress resilience, and decreased negative effect of Survival Roles. MNRI® proposes a new paradigm in the realm of personality growth and socio-interpersonal activity, and supports the neurophysiological aspects to optimize the overall quality of life of business professionals from a variety of high management business areas.

On reflexivity and the conduct of the self in everyday life: reflections on Bourdieu and Archer.

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Akram, Sadiya; Hogan, Anthony

2015-12-01

This article provides a critique of the concept of reflexivity in social theory today and argues against the tendency to define agency exclusively in terms of reflexivity. Margaret Archer, in particular, is highlighted as a key proponent of this thesis. Archer argues that late modernity is characterized by reflexivity but, in our view, this position neglects the impact of more enduring aspects of agency, such as the routinization of social life and the role of the taken-for-granted. These concepts were pivotal to Bourdieu and Giddens' theorization of everyday life and action and to Foucault's understanding of technologies of the self. We offer Bourdieu's habitus as a more nuanced approach to theorizing agency, and provide an alternative account of reflexivity. Whilst accepting that reflexivity is a core aspect of agency, we argue that it operates to a backdrop of the routinization of social life and operates from within and not outside of habitus. We highlight the role of the breach in reflexivity, suggesting that it opens up a critical window for agents to initiate change. The article suggests caution in over-ascribing reflexivity to agency, instead arguing that achieving reflexivity and change is a difficult and fraught process, which has emotional and moral consequences. The effect of this is that people often prefer the status quo, rather than to risk change and uncertainty. © London School of Economics and Political Science 2015.

Diagnostic utility of the acoustic reflex in predicting hearing in paediatric populations.

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Pérez-Villa, Yolanda E; Mena-Ramírez, María E; Aguirre, Laura E Chamlati; Mora-Magaña, Ignacio; Gutiérrez-Farfán, Ileana S

2014-01-01

The sensitivity of prediction of acoustic reflex, in determining the level of hearing loss, is especially useful in paediatric populations. It is based on the difference between the pure tone stapedius reflex threshold and contralateral white noise. The white noise threshold was 60 dB and that of pure tone was 80 dB. Our objective was to determine the diagnostic sensitivity of the prediction of the acoustic reflex. We studied children aged <10 years, from October 2011 to May 2012, by measuring the acoustic reflex with white noise and pure tone. We used contrast tests, with X2 and student t-test. Concordance was measured with Kappa. Results were considered significant at P≤.05. Our protocol was approved by Institutional Ethics Committee. Informed consent was obtained from the parents in all cases. Prediction of normal hearing was 0.84 for the right ear and 0.78 in left ear, while for hearing loss of an unspecified grade, it was 0.98 for the right ear and 0.96 in the left ear. Kappa value was 0.7 to 0.6 for the right ear and left ear. The acoustic reflex is of little diagnostic utility in predicting the degree of hearing loss, but it predicts more than 80% of normal hearing. The clinical utility of the reflex is indisputable, as it is an objective method, simple and rapid to use, that can be performed from birth and whose results are independent of the cooperation and willingness of the subject. It is proposed as an obligatory part of hearing screening. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

The static actuation of dielectric elastomer actuators: how does pre-stretch improve actuation?

International Nuclear Information System (INIS)

Kofod, Guggi

2008-01-01

It has previously been shown that providing dielectric elastomer actuators with a level of pre-stretch can improve properties such as breakdown strength, actuation strain and efficiency. The actuation in such actuators depends on an interplay between the highly nonlinear hyperelastic stress-strain behaviour with the electrostatic Maxwell's stress; however, the direct effects of pre-stretch on the electromechanical coupling have still not been investigated in detail. We compare several experimental results found in the literature on the hyperelastic parameters of the Ogden model for the commonly used material VHB 4910, and introduce a more detailed and thus more accurate fit to a previous uniaxial stress-strain experiment. Electrostatic actuation models for a pure shear cuboid dielectric elastomer actuator with pre-stretch are introduced, for both intensive and extensive variables. For both intensive and extensive variables the constant strain (blocked stress or force) as well as the actuation strain is presented. It is shown how in the particular case of isotropic amorphous elastomers the pre-stretch does not affect the electromechanical coupling directly, and that the enhancement in actuation strain due to pre-stretch occurs through the alteration of the geometrical dimensions of the actuator. Also, the presence of the optimum load is explained as being due to the plateau region in the force-stretch curve, and it is shown that pre-stretch is not able to affect its position. Finally, it is shown how the simplified Ogden fit leads to entirely different conclusions for actuation strain in terms of extensive variables as does the detailed fit, emphasizing the importance of employing accurate hyperelastic models for the stress-stretch behaviour of the elastomer.

Acute effect of different stretching methods on flexibility and jumping performance in competitive artistic gymnasts.

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Dallas, G; Smirniotou, A; Tsiganos, G; Tsopani, D; Di Cagno, A; Tsolakis, Ch

2014-12-01

The purpose of this study was to investigate the acute effects of 3 different warm up methods of stretching (static, proprioceptive neuromuscular facilitation, and stretching exercises on a Vibration platform) on flexibility and legs power-jumping performance in competitive artistic gymnasts. Eighteen competitive artistic gymnasts were recruited to participate in this study. Subjects were exposed to each of 3 experimental stretching conditions: static stretching (SS), proprioceptive neuromuscular facilitation stretching (PNF), and stretching exercises on a Vibration platform (S+V). Flexibility assessed with sit and reach test (S & R) and jumping performance with squat jump (SJ) and counter movement jump (CMJ) and were measured before, immediately after and 15 min after the interventions. Significant differences were observed for flexibility after all stretching conditions for S+V (+1.1%), SS (+5.7%) and PNF (+6.8%) (P=0.000), which remained higher 15 min after interventions (S+V (1.1%), SS (5.3%) and PNF (5.5%), respectively (P=0.000). PNF stretching increased flexibility in competitive gymnasts, while S+V maintained jumping performance when both methods were used as part of a warm-up procedure.

The effect of varying plyometric volume on stretch-shortening cycle capability in collegiate male rugby players.

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Jeffreys, Mark; De Ste Croix, Mark; Lloyd, Rhodri S; Oliver, Jon L; Hughes, Jonathan

2017-03-25

The purpose of this study was to identify the effectiveness of low and high volume plyometric loads on developing stretch shortening cycle capability in collegiate rugby players. A between- group repeated measures design was used. Thirty six subjects (age 20.3 ±1.6 yrs, mass 91.63 ±10.36kg, stature 182.03 ±5.24cm) were randomly assigned to one of three groups, a control group (CG), a low volume plyometric group (LPG) or a high volume plyometric group (HPG). Data were collected from a force plate, and measures of reactive strength index (RSI) and leg stiffness were calculated from jump height, contact time and flight time. A significant between group × time (F = 4.01, P plyometric program. The low volume program elicited the same performance improvement in RSI as a high volume program whilst undertaking a lower dose. This suggests that strength and conditioning coaches may be able to benefit from the ability to develop more time efficient and effective plyometric programs.

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios

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Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

2015-01-01

AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P hamstring muscle strength at both the 60°/s and 180°/s test speeds (P 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05). CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines. PMID:26495249

Prognostic Value of Impaired Preoperative Ankle Reflex in Surgical Outcome of Lumbar Disc Herniation

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Farzad Omidi-Kashani

2016-01-01

Full Text Available Background: Several prognostic factors exist influencing the outcome of surgical discectomy in the patients with lumbar disc herniation (LDH. The aim of this study is to evaluate the relationship between severity of preoperative impaired ankle reflex and outcomes of lumbar discectomy in the patients with L5-S1 LDH. Methods: We retrospectively evaluated 181 patients (108 male and 73 female who underwent simple discectomy in our orthopedic department from April 2009 to April 2013 and followed them up for more than one year. The mean age of the patients was 35.3±8.9 years old. Severity of reflex impairment was graded from 0 to 4+ and radicular pain and disability were assessed by visual analogue scale (VAS and Oswestry disability index (ODI questionnaires, respectively. Subjective satisfaction was also evaluated at the last follow-up visit. Chi-square and Kruskal-Wallis tests were used to compare qualitative variables. Results: Reflex impairment existed in 44.8% preoperatively that improved to 10% at the last follow-up visit. Statistical analyses could not find a significant relationship between the severity of impaired ankle reflex and sex or age (P=0.538 and P=0.709, respectively. There was a remarkable relationship between severity of reflex impairment and preoperative radicular pain or disability (P=0.012 and P=0.002, respectively. Kruskal-Wallis test showed that a more severity in ankle reflex impairment was associated with not only less improvement in postoperative pain and disability but also less satisfaction rate (P Conclusions: In the patients with L5-S1 LDH, more severe ankle reflex impairment is associated with less improvement in postoperative pain, disability, and subjective satisfaction.

The effects of static stretch duration on the flexibility of hamstring ...

African Journals Online (AJOL)

The effects of static stretch duration on the flexibility of hamstring muscles. NA Odunaiya, TK Hamzat, OF Ajayi. Abstract. The effects of duration of a static stretching protocol (Intervention) on hamstrings tightness were evaluated. Sixty purposively sampled subjects with unilateral hamstring tightness that had no history of low ...

Evaluating Red Reflex and Surgeon Preference Between Nearly-Collimated and Focused Beam Microscope Illumination Systems.

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Cionni, Robert J; Pei, Ron; Dimalanta, Ramon; Lubeck, David

2015-08-01

To evaluate the intensity and stability of the red reflex produced by ophthalmic surgical microscopes with nearly-collimated versus focused illumination systems and to assess surgeon preference in a simulated surgical setting. This two-part evaluation consisted of postproduction surgical video analysis of red reflex intensity and a microscope use and preference survey completed by 13 experienced cataract surgeons. Survey responses were based on bench testing and experience in a simulated surgical setting. A microscope with nearly-collimated beam illumination and two focused beam microscopes were assessed. Red reflex intensity and stability were greater with the nearly-collimated microscope illumination system. In the bench testing survey, surgeons reported that the red reflex was maintained over significantly greater distances away from pupillary center, and depth of focus was numerically greater with nearly-collimated illumination relative to focused illumination. Most participating surgeons (≥64%) reported a preference for the microscope with nearly-collimated illumination with regard to red reflex stability, depth of focus, visualization, surgical working distance, and perceived patient comfort. The microscope with nearly-collimated illumination produced a more intense and significantly more stable red reflex and was preferred overall by more surgeons. This is the first report of an attempt to quantify red reflex intensity and stability and to evaluate surgically-relevant parameters between microscope systems. The data and methods presented here may provide a basis for future studies attempting to quantify differences between surgical microscopes that may affect surgeon preference and microscope use in ophthalmic surgery.

The acute effects of stretching with vibration on dynamic flexibility in young female gymnasts.

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Johnson, Aaron W; Warcup, Caisa N; Seeley, Matthew K; Eggett, Dennis; Feland, Jeffery B

2018-01-10

While stretching with vibration has been shown to improve static flexibility; the effect of stretching with vibration on dynamic flexibility is not well known. The purpose of this study was to examine the effectiveness of stretching with vibration on acute dynamic flexibility and jump height in novice and advanced competitive female gymnasts during a split jump. Female gymnast (n=27, age: 11.5 ± 1.7 years, Junior Olympic levels 5-10) participated in this cross-over study. Dynamic flexibility during gymnastic split jumps were video recorded and analyzed with Dartfish software. All participants completed both randomized stretching protocols with either the vibration platform turned on (VIB) (frequency of 30 Hz and 2 mm amplitude) or off (NoVIB) separated by 48 h. Participants performed 4 sets of three stretches on the vibration platform. Each stretch was held for 30 s with 5 s rest for a total of 7 min of stretch. Split jump flexibility decreased significantly from pre to post measurement in both VIB (-5.8°±5.9°) (p<0.001) and NoVIB (-2.6°±6.1°) (p=0.041) conditions (adjusted for gymnast level). This effect was greatest in lower skill level gymnasts (p=0.003), while the highest skill level gymnasts showed no significant decrease in the split jump (p=0.105). Jump height was not significantly different between conditions (p=0.892) or within groups (p=0.880). An acute session of static stretching with or without vibration immediately before performance does not alter jump height. Stretching with vibration immediately prior to gymnastics competition decreases split jump flexibility in lower level gymnasts more than upper level gymnasts.

Plantar reflex excitability is increased in the evening in restless legs syndrome patients.

Science.gov (United States)

Dafkin, Chloe; Green, Andrew; Olivier, Benita; McKinon, Warrick; Kerr, Samantha

2017-11-01

To investigate if diurnal changes in spinal excitability (plantar reflex) occur in restless legs syndrome (RLS) participants compared to healthy matched controls. Thirteen RLS participants and 13 healthy control participants' plantar reflex responses were evaluated in the evening (PM) and the morning (AM). Plantar reflex responses were assessed electromyographically, using motion analysis (kinematically) and by subjective nociception (Visual Analogue Scale). RLS participants showed a circadian variation in plantar reflex responses whilst control participants did not. Evening ankle angle changes were larger and faster in RLS participants compared to morning responses. In addition RLS participants displayed significantly smaller change in ankle angle and significantly slower ankle movements in the evening and the morning as well as significantly lower lateral gastrocnemius maximum amplitude in the compared to control participants. The findings of the current study support the theory of RLS circadian fluctuations in spinal excitability. An unexpected finding was decreased plantar reflex responses in RLS participants compared to healthy control participants. However this finding supports the theory of mechanical hypoesthesia in RLS. The results of this study provide further insight into the pathophysiology of RLS, highlighting that not all sensory processing is affected in the same manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Vestibuloocular reflex dynamics during high-frequency and high-acceleration rotations of the head on body in rhesus monkey.

Science.gov (United States)

Huterer, Marko; Cullen, Kathleen E

2002-07-01

For frequencies >10 Hz, the vestibuloocular reflex (VOR) has been primarily investigated during passive rotations of the head on the body in humans. These prior studies suggest that eye movements lag head movements, as predicted by a 7-ms delay in the VOR reflex pathways. However, Minor and colleagues recently applied whole-body rotations of frequencies unity (1.1 at 5 Hz vs. 1.2 at 25 Hz), and phase lag increased only slightly with frequency (from 2 degrees at 5 Hz to 11 degrees at 25 Hz, a marked contrast to the 63 degrees lag at 25 Hz predicted by a 7-ms VOR latency). Furthermore, VOR response dynamics were comparable in darkness and when viewing a target and did not vary with peak velocity. Although monkeys offered less resistance to the initial cycles of applied head motion, the gain and phase of the VOR did not vary for early versus late cycles, suggesting that an efference copy of the motor command to the neck musculature did not alter VOR response dynamics. In addition, VOR dynamics were also probed by applying transient head perturbations with much greater accelerations (peak acceleration >15,000 degrees /s(2)) than have been previously employed. The VOR latency was between 5 and 6 ms, and mean gain was close to unity for two of the three animals tested. A simple linear model well described the VOR responses elicited by sinusoidal and transient head on body rotations. We conclude that the VOR is compensatory over a wide frequency range in monkeys and has similar response dynamics during passive rotation of the head on body as during passive rotation of the whole body in space.

A Study on the Effects of Bee Venom Aqua-Acupuncture on Writhing Reflex

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Jeong Sun-Hee

2000-07-01

Full Text Available Introduction:In spite of the use of Bee Venom aqua-acupuncture in the clinics, the scientific evaluation on effects is not enough. Bee Venom aqua-acupuncture is used according to the stimulation of acupuncture point and the chemical effects of Bee Venom. The aims of this study is to investigate the analgegic effects of the Bee Venom aqua-acupuncture, through the change of writhing reflex Materials and Methods:Pain animal model was used acetic acid method. The changes of writhing reflex of the mice which were derived pain by injecting acetic acid into the abdomen, after stimulating Bee Venom aqua-acupuncture on Chungwan(CV12 and non acupuncture point on the backside were measured. Results:1. It showed that the writhing reflex were appeared on the groups which injected acetic acid only, and saline-acetic acid group(sample I, but not on the group bee venom-saline group(sample II. 2. The change of writhing reflex by Chungwan(CV12 Bee Venom aqua-acupuncture showed significant decrease in the order of Chungwan(CV12 Bee Venom aqua-acupuncture group III(2.5×10-3g/kg, II(2.5×10-4g/kg, and I(2.5×10-5g/kg, compared with control group. There were significant decrease of number of writhing reflex in 5～10, 10～15 and 15～20 minutes intervals of Chung wan(CV12 Bee Venom aqua-acupuncture group I, and in 0～5, 5～10, 10～15 and 15～20 minutes intervals of II and III, compared with control group. 3. The change of writhing reflex by non acupuncture point Bee Venom aqua-acupuncture showed significant decrease in the 0～5 and 5～10 minutes intervals and the total number of writhing reflex in 2.5×10-4g/kg group, compared with control group 4. The effects of writhing reflex of Chungwan(CV12 Bee Venom aqua-acupuncture group showed significant decrease, compared with non acupuncture point Bee Venom aqua-acupuncture group. Conclusion:This study shows that the Bee Venom aqua-acupuncture on Chungwan(CV12 decreases the numbers of writhing reflex. As the

Mechanical stretch endows mesenchymal stem cells stronger angiogenic and anti-apoptotic capacities via NFκB activation

International Nuclear Information System (INIS)

Zhu, Zhuoli; Gan, Xueqi; Fan, Hongyi; Yu, Haiyang

2015-01-01

Mesenchymal stem cells (MSCs) have been broadly used for tissue regeneration and repair due to their broad differentiation potential and potent paracrine properties such as angiogenic capacity. Strategies to increase their survival rate after transplantation and the angiogenic ability are of priority for the utility of MSCs. In this study, we found that mechanical stretch (10% extension, 30 cycles/min cyclic stretch) preconditioning increase the angiogenic capacity via VEGFA induction. In addition, mechanical stretch also increases the survival rate of mesenchymal stem cells under nutrients deprivation. Consistent with the increase VEGFA expression and resistance to apoptosis, nuclear localization of NFκB activity p65 increased upon mechanical stretch. Inhibition of NFκB activity by BAY 11-708 blocks the pro-angiogenesis and anti-apoptosis function of mechanical stretch. Taken together, our findings here raise the possibility that mechanical stretch preconditioning might enhance the therapeutic efficacy of mesenchymal stem cells. - Highlights: • Mechanical stretch increases the angiogenic capacity via VEGFA induction in MSCs. • Mechanical stretch increases the survival rate of MSCs under nutrients deprivation. • Mechanical stretch manipulates MSCs via the activation of NFκB.

Mechanical stretch endows mesenchymal stem cells stronger angiogenic and anti-apoptotic capacities via NFκB activation

Energy Technology Data Exchange (ETDEWEB)

Zhu, Zhuoli; Gan, Xueqi [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Fan, Hongyi [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Yu, Haiyang, E-mail: yhyang6812@foxmail.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)

2015-12-25

Mesenchymal stem cells (MSCs) have been broadly used for tissue regeneration and repair due to their broad differentiation potential and potent paracrine properties such as angiogenic capacity. Strategies to increase their survival rate after transplantation and the angiogenic ability are of priority for the utility of MSCs. In this study, we found that mechanical stretch (10% extension, 30 cycles/min cyclic stretch) preconditioning increase the angiogenic capacity via VEGFA induction. In addition, mechanical stretch also increases the survival rate of mesenchymal stem cells under nutrients deprivation. Consistent with the increase VEGFA expression and resistance to apoptosis, nuclear localization of NFκB activity p65 increased upon mechanical stretch. Inhibition of NFκB activity by BAY 11-708 blocks the pro-angiogenesis and anti-apoptosis function of mechanical stretch. Taken together, our findings here raise the possibility that mechanical stretch preconditioning might enhance the therapeutic efficacy of mesenchymal stem cells. - Highlights: • Mechanical stretch increases the angiogenic capacity via VEGFA induction in MSCs. • Mechanical stretch increases the survival rate of MSCs under nutrients deprivation. • Mechanical stretch manipulates MSCs via the activation of NFκB.

Creating safety by strengthening clinicians' capacity for reflexivity

Science.gov (United States)

2011-01-01

This commentary explores the nature of creating safety in the here-and-now. Creating safety encompasses two dimensions: revisiting specific behaviours by focusing on substandard performance (reflection), and a more broad-ranging attention to everyday behaviours that are taken as given (reflexivity). The piece pays particular attention to this second dimension of creating safety. Two techniques that promote reflexivity are discussed: video-filming real-time, everyday clinical practice and inviting clinicians' feedback about their own footage, and reflecting on the knowledge and questions that patients and families have about their care, and about unexpected outcomes and clinical incidents. The piece concludes that feedback about everyday practice using these methods is critical to enhancing the safety of everyday activity. PMID:21450780

A method of reflexive balancing in a pragmatic, interdisciplinary and reflexive bioethics.